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* Note that all times are in local (Berlin) time, that is, in CEST.

Day 1 : 06 Sept. 2021

09:00 - 10:00
Opening Session : Sławomir Stańczak and Eduard A. Jorswieck
10:00 - 11:00
Regular Session 1 : Machine Learning for Wireless Network Optimization
Chair: Lanfranco Zanzi (NEC Laboratories Europe, ).
10:00 - 10:10Interference-Aware Distributed Predictive Resource Allocation for Automotive Applications
Daniel Fabian Külzer, Slawomir Stanczak, Mladen Botsov.
        Autonomous driving will rely on several safety-related connected applications that coexist with infotainment services for passenger entertainment. The simultaneous provisioning of resources to services with different quality of service requirements poses an immense challenge for future cellular networks. While most safety-related applications require low latencies, infotainment services usually necessitate a high average throughput. We propose a multi-cell, distributed predictive resource allocation framework with interference coordination based on channel distribution information to address the coexistence challenges. The approach first shifts packet transmission times in the so-called statistical look-ahead scheduling (SLAS) step, leveraging service properties. Inter-cell interference is coordinated by base station communication and a low-complexity fractional interference approximation. Lastly, packets are forwarded to an online scheduler according to the found transmission schedule. Moreover, we present a convolutional neural network to reduce the computational complexity in the SLAS step. Simulations show that the distributed approach performs very close to a central-controller solution at significantly lower computational complexity. It outperforms state-of-the-art schedulers in terms of transmission reliability and spectral efficiency.
10:10 - 10:20On The Usage of Gaussian Processes for Visible Light Positioning With Real Radiation Patterns
Willem Raes, Tom Dhaene, Nobby Stevens.
        In this work the performance of a two dimensional, Received Signal Strength-based Visible Light Positioning strategy using multilateration, that assumes ideal Lambertian radiation patterns, is compared to a data-based machine learning strategy that uses Gaussian Process regression to perform localization. The results are obtained from a simulation framework that leverages the accurately measured radiation patterns of four off-the-shelf LEDs, which are specified by the manufacturer to be Lambertian sources. The main results are that when using the idealized Lambertian model for localization a significant bias is introduced with a p95 error of up to 14.1 cm, while the data-based approach using a Gaussian Process for localization proves to be much better suited, delivering a p95 error of 1.26 cm in the best performing considered scenario.
10:20 - 10:30A Concurrent Training Method of Deep-Learning Autoencoders in a Multi-user Interference Channel
Lloyd Pellatt, Maziar Nekovee, Dehao Wu.
        Autoencoder (AE) has been proposed recently as a promising, and potentially disruptive approach to design the physical layer (PHY) of future beyond-5G networks. In this paper, we propose a novel concurrent and interactive training method for autoencoder-based physical layer for the multi-user interference channel scenario, which is highly relevant to beyond-5G dense systems. In our approach, AEs use a concurrent training approach in order to minimise the interference in the presence of other AEs. Deep learning-based AE design for a multi-user interference channel is proposed in a dense urban environment where the AE is adapted to the interference from nearby intelligent base stations (BSs) by considering other BSs randomly distributed over 200 meters. Interference is modelled based on a 3GPP channel model in an urban microcell environment. We simulate and test the system, and compare the performance with a conventional QPSK modulation in an additive white Gaussian noise (AWGN) channel. Results show that at low signal-to-noise ratios, the AE in an interference channel delivers similar performance to that of QPSK in a noisy channel. However, at high signal-to-noise ratios, every trained AE outperforms the theoretical limit for QPSK systems in a noisy channel, in an interference-limited environment. The learned constellations is studied. We show that AEs can augment their own transmitted symbols based on the interference from nearby BSs via a learning process, which can counteract the effects of channel noise.
10:30 - 10:40Detecting Similar and Dissimilar Movement Patterns using Indoor Passive Localization
Kunal Soni, Syed Faraz Hasan, Mohammad Hossain Dehghan Shoar, Nazmul Haq Siddique.
        This paper covers passive localization of a device-free user such that the user is not involved in the positioning system. We use the so-called device-free passive localization approach to estimate the most likely movement pattern exhibited by a remote-controlled, passive robot while moving at a walking speed. Our estimation is based only on the changes in received signal strength as a result of the concerned movement patterns of the robot. This involves observation of physical movement of the robot within an indoor area covered by Wi-Fi signals and its resulting impact on the radio environment. We show that the movement patterns of a remotely controlled robot can be predicted from the signal features.
11:00 - 12:00
Regular Session 2 : Ultra-Reliable Low Latency Communication (URLLC)
Chair: Daniel Fabian Külzer (BMW Group Research and Technology, ).
11:00 - 11:10Time synchronization performance analysis considering the frequency offset inside 5G-TSN network
Jiajia Song, Makoto Kubomi, Jeffrey Zhao, Daisuke Takita.
        Fifth generation mobile communication system (5G) integrated with Time Sensitive Networking (TSN) has been deemed as a holistic solution for realizing Industry 4.0, wherein high accuracy of time synchronization is required to enable end-to-end deterministic communication between wireless and wired devices. 3rd Generation Partnership Project(3GPP) TS 23.501 Release 16 has defined the time synchronization mechanism of industrial automation in a 5G-TSN network. This paper briefly reviews the time synchronization scheme of Release 16 and presents the time precision performance considering frequency offset inside 5G System(5GS). It is revealed that frequency offset inside 5GS leads to several microseconds of time error when transmission delay is several tens of milliseconds. As industrial applications require less than 1 microsecond time synchronicity in motion control, the effect of frequency offset inside 5GS needs to be mitigated. In the later part of this paper, a novel method to estimate the frequency offset inside 5GS is presented. The proposed method can be implemented in a simple and effective manner.
11:10 - 11:20Enhancements of PUSCH repetitions for URLLC in licensed and unlicensed spectrum
Trung-Kien Le, Umer Salim, Florian Kaltenberger.
        Ultra-reliable low-latency communication (URLLC) is specified in 5G New Radio to serve the applications and services with the strict requirements of reliability and latency. The URLLC operation is in licensed spectrum then extended to unlicensed spectrum to support new use cases in the industrial scenario. This requires new features in physical layer to make URLLC work with the strict requirements in both licensed and unlicensed spectrum. This paper focuses on the design of physical uplink shared channel (PUSCH) repetitions for URLLC. In PUSCH repetition, the nominal PUSCH repetitions might be segmented into the smaller actual repetitions due to uplink/downlink (UL/DL) directions in time division duplex (TDD) configuration or slot boundary. This segmentation causes a degradation of the URLLC performance due to a smaller number of valid symbols for PUSCH repetitions, a drop of the repetition in an orphan symbol and an increase of listen before talk (LBT) overhead. To enhance the URLLC performance, two schemes are proposed. The first scheme deals with segmentation due to UL/DL directions by dynamically switching the chosen semi-static DL symbols to UL symbols. The second scheme deals with orphan symbols by transmitting signal in these symbols in order to maintain a continuous PUSCH transmission and avoid an additional LBT. The results show an improvement of URLLC performance in licensed and unlicensed spectrum by applying these two schemes.
11:20 - 11:30Error Probability Minimization of Multi-hop Relaying System in the Finite Blocklength Regime
Yao Zhu, Xiaopeng Yuan, Yulin Hu, Qimei Chen, Anke Schmeink.
        Multi-hop relaying is a promising technology to enhance the system performance, especially for the scenario with a long distance wireless transmission or a direct transmission link having terrible channel fading. In this paper, we study a multi-hop relaying network operating with finite blocklength codes. We provide a joint system design with respect to the relay selection, power control and blocklength allocation with the aim to minimize the overall error probability. An integer non-convex optimization problem is formulated accordingly. By applying a tight approximation of the overall error probability, the problem is reformulated as an integer convex problem which can be efficiently solved. Via simulation, we validate the convex properties and provide the insight for the relay selection based on variant system setups.
11:30 - 11:40Relaying-Assisted Multiuser Networks in FBL Regime: Achievable Reliability-Constrained Throughput
Xiaopeng Yuan, Yao Zhu, Yulin Hu, Deshi Li, Anke Schmeink.
        In this work, we study a multi-user relaying network operating with finite blocklength (FBL) codes, where a single relay node is responsible for relaying the data from a source node to multiple users. We consider two relaying principles, i.e., decode-and-forward (DF) and amplify-and-forward (AF) relaying, together with two downlink strategies for relaying to multiple users, i.e., broadcasting and time division multiple access (TDMA), which result in total in four combinations. Taking the fairness into account, we formulate optimization problems to maximize the minimum throughput among all users via blocklength allocation, while guaranteeing the reliability. We start with the combination strategy of TDMA-DF, where the DF relay serves multiple users in a TDMA manner in the second hop. To solve the nonconvex problem, we have constructed a convex approximation for the problem and accordingly proposed iterative algorithm, which is capable of iteratively improving the minimum throughput until a convergence to a suboptimal point. Afterwards, the iterative algorithm is then extended to other combinations, i.e., broadcasting-DF and TDMA-AF, while for broadcasting-AF, the optimal blocklength allocation can be directly derived out. Finally, via simulation results, we validate the convergence of our proposed iterative algorithms, and by comparison depict the benefits of DF relaying over AF relaying and the advantages of broadcasting and TDMA strategies in different scenarios.
12:00 - 13:00
Special Session 1 : Age of Information
Chair: Nikolaos Pappas (Linköping University, ).
12:00 - 12:10Analysis of AoI Violation Probability in Wireless Networks
Meiyan Song, Howard Yang, Hangguan Shan, Jemin Lee, Huaming Lin, Tony Q. S. Quek.
        The rapid development of the Internet of Things has led to the rise of many real-time applications, which are highly dependent on timely information delivery to respond correctly to changes in the surrounding environment. Therefore, age of information (AoI) has aroused widespread attention as a new metric to evaluate information freshness at the destination. In this paper, we investigate the effect of the retransmission mechanism and updating patterns on the AoI performance. Different from the existing work that considers the average value of AoI, we adopt violation probability, the probability that AoI exceeds a certain threshold, as the metric for meeting the strict timeliness requirements of different applications. We obtain closed-form expressions of AoI violation probability for active sources and buffered sources under last-come-first-served discipline with packet discarding. The accuracy of the analyses is verified through simulations. Numerical results show that the buffered sources with periodic arrivals have better performance in terms of information freshness given service rate and updating rate.
12:10 - 12:20Age-Oriented Scheduling of Correlated Sources in Multi-server System
Ly Minh Hoang, Josu Doncel, Mohamad Assaad.
        This paper investigates a system formed by N sources, each of them sending status updates of a process of interest though a multiserver queue. Taking into consideration the mutual correlation across different sources, we propose an innovative model in which this correlation was modelled as an additional, virtual information source. Assuming that replication of packets to multiple servers is allowed, we present a policy to reduce the sum age of information (AoI) of these N sources. Our numerical results demonstrate the superiority of the proposed policy when compared to the popular Last-Generate First-Serve policy.
12:20 - 12:30Source-Aware Packet Management for Computation-Intensive Status Updating: MGF of the AoI
Mohammad Moltafet, Markus Leinonen, Marian Codreanu.
        We consider a multi-source status update system consisting of two independent sources and one server. The packets of different sources are generated according to a Poisson process and served according to an exponentially distributed service time. We assume that the received status update packets need further processing before being used (hence, computation-intensive). This is mathematically modeled by introducing an additional server at the sink node. The sink server serves the packets according to an exponentially distributed service time. We derive the moment generating function (MGF) of the AoI of each source under a source-aware packet management policy. According to this policy, when a server (either the transmitter or sink server) is busy at the arrival of a packet, the packet currently under service is preempted only if the arriving packet is from the same source (hence, source-aware). Numerical results are provided to assess the results.
12:30 - 12:40Evaluation of Age Control Protocol (ACP) and ACP+ on ESP32
Umut Guloglu, Sajjad Baghaee, Elif Uysal.
        Age Control Protocol (ACP) and its enhanced version, ACP+, are recently proposed transport layer protocols to control Age of Information of data flows. This study presents an experimental evaluation of ACP and ACP+ on the ESP32 microcontroller, a currently popular IoT device. We identify several issues related to the implementation of these protocols on this platform and in general on short-haul, low-delay connections. We propose solutions to overcome these issues in the form of simple modifications to ACP+, and compare the performance of the resulting modified ACP+ with that of the original protocols on a small-delay local wireless IoT connection.
12:40 - 12:50Timely Updating with Intermittent Energy and Data for Multiple Sources over Erasure Channels
Christopher Daniel, Ahmed Arafa.
        A status updating system is considered in which multiple data sources generate packets to be delivered to a destination through a shared energy harvesting sensor. Only one source's data, when available, can be transmitted by the sensor at a time, subject to energy availability. Transmissions are prune to erasures, and each successful transmission constitutes a status update for its corresponding source at the destination. The goal is to schedule source transmissions such that the collective long-term average age-of-information (AoI) is minimized. AoI is defined as the time elapsed since the latest successfully-received data has been generated at its source. To solve this problem, the case with a single source is first considered, with a focus on threshold waiting policies, in which the sensor attempts transmission only if the time until both energy and data are available grows above a certain threshold. The distribution of the AoI is fully characterized under such a policy. This is then used to analyze the performance of the multiple sources case under maximum-age-first scheduling, in which the sensor's resources are dedicated to the source with the maximum AoI at any given time. The achievable collective long-term average AoI is derived in closed-form. Multiple numerical evaluations are demonstrated to show how the optimal threshold value behaves as a function of the system parameters, and showcase the benefits of a threshold-based waiting policy with intermittent energy and data arrivals.
13:00 - 14:00
Special Session 2 : Coding for Communications and Security
Chair: Hannes Bartz (German Aerospace Center, ).
13:00 - 13:10Reed-Solomon Coded Compressed Sensing for the Unsourced Random Access
Kirill Andreev, Pavel Rybin, Alexey Frolov.
        We consider a coded compressed sensing approach for the unsourced random access problem. We replace the outer tree code proposed by Amalladinne et al. with a list recoverable Reed--Solomon code. Numerical experiments in the single antenna quasi-static Rayleigh fading channel show that the proposed scheme allows improving the performance of a tree code-based scheme when the number of active users is less than 200.
13:10 - 13:20Decoding of Moderate Length LDPC Codes via Learned Clustered Check Node Scheduling
Salman Habib, Allison Beemer, Joerg Kliewer.
        In this work, we consider the sequential decoding of moderate length low-density parity-check (LDPC) codes via reinforcement learning (RL). The sequential decoding scheme is modeled as a Markov decision process (MDP), and an optimized decoding policy is subsequently obtained via RL. In contrast to our previous works, where an agent learns to schedule only a single check node (CN) within a group (cluster) of CNs per iteration, in this work we train the agent to schedule all CNs in a cluster, and all clusters in every iteration. That is, in each RL step, an agent learns to schedule CN clusters sequentially depending on the reward associated with the outcome of scheduling a particular cluster. We also propose a modified MDP and a uniform sequential decoding policy, enabling the RL-based decoder to be suitable for much longer LDPC codes than the ones studied in our previous work. The proposed RL-based decoder exhibits an SNR gain of almost 0.8 dB for fixed bit error probability over the standard flooding approach.
13:20 - 13:30Low Rate Protograph-Based LDPC Codes for Continuous Variable Quantum Key Distribution
Kadir Gumus, Laurent Schmalen.
        Error correction plays a major role in the reconciliation of continuous variable quantum key distribution (CV-QKD) and greatly affects the performance of the system. CV-QKD requires error correction codes of extremely low rates and high reconciliation efficiencies. There are only very few code designs available in this ultra low rate regime. In this paper, we introduce a method for designing protograph-based ultra low rate LDPC codes using differential evolution. By proposing type-based protographs, a new way of representing low rate protograph-based LDPC codes, we drastically reduce the complexity of the protograph optimization, which enables us to quickly design codes over a wide range of rates. We show that the codes resulting from our optimization outperform the codes from the literature both in regards to the threshold and in finite-length performance, validated by Monte-Carlo simulations, showing gains in the regime relevant for CV-QKD.
13:30 - 13:40Low-Latency Distributed Inference at the Network Edge Using Rateless Codes
Anton Frigård, Siddhartha Kumar, Eirik Rosnes, Alexandre Graell i Amat.
        We propose a coding scheme for low-latency distributed inference at the network edge that combines a rateless code with an irregular-repetition code. The rateless code provides robustness against straggling servers and serves the purpose of reducing the computation latency, while the irregular-repetition code provides spatial diversity to reduce the communication latency. We show that the proposed scheme yields significantly lower latency than a scheme based on maximum distance separable codes recently proposed by Zhang and Simeone.
14:00 - 15:00
Special Session 3 : Edge Computing
Chair: Yulin Hu (RWTH Aachen University, ).
14:00 - 14:10Distributed Resource Allocation Under Mobile Edge Computing Networks
Yang Yang, Qimei Chen.
        Long-term evolution in unlicensed spectrum (LTEU) can make use of centralized scheduling, interference coordination and other technologies to achieve better spectrum efficiency (SE). As the evolution of cloud computing, mobile edge computing (MEC) sinks the computing and storage capacity from the centralized data center to the edge of the network, which is the key technology to achieve low delay and high speed. However, the traditional centralized scheme in small cell networks (SCNs) structure will bring huge signal overheads. In order to adapt to the complex and changeable network system, this paper proposes a distributed resource and power allocation scheme under MEC environment, which enables small base stations (SBSs) to work autonomously. The SBSs need only little information exchange through the information cloud (IC) and finally obtain the global optimal SE. Simulation results confirm the correctness and effectiveness of the proposed scheme, and demonstrate the superiority of the distributed scheme over the centralized scheme.
14:10 - 14:20Reliability-Optimal Designs in MEC Networks with Finite Blocklength codes and Outdated CSI
Yang Yang, Yulin Hu, M. Cenk Gursoy.
        There has been an increasing interest in mobile edge computing (MEC) in recent years. Different from the traditional centralized cloud computing, MEC servers are deployed at the edges of networks such as at base stations (BSs) and access points (APs), in order to support computation-intensive and latency-critical applications. In this paper, we consider a multi-user mobile edge computing (MEC) network in which the wireless data transmission/offloading is performed using finite blocklength (FBL) codes to satisfy the latency constraints. The reliability in the communication phase is characterized in the FBL regime, while the event of queue length violation in the computation phase is investigated via exploiting the extreme value theory. We first formulate the overall optimization problem in the scenario of multiple user equipments (UEs) aiming to minimize the maximal end-to-end error probability among all UEs under both the FBL and energy consumption constraints. We further propose a two-level learning-based approach to jointly determine time allocations in the FBL regime, the UEs' offloading decisions and MEC computational resource allocations to solve the overall optimization problem. Simulation results demonstrate that the proposed two-level learning-based algorithm solves the problem efficiently.
14:20 - 14:30Resource Allocation for Multi-access Edge Computing with Fronthaul and Backhaul Constraints
Jun Chen, Zheng Chang, Xijuan Guo, Timo Hämäläinen.
        Edge computing is able to provide proximity solutions for the future wireless network to accommodate different types of devices with various computing service demands. Meanwhile, in order to provide ubiquitous connectivities to massive devices over a relatively large area, densely deploying remote radio head (RRH) is considered as a cost-efficient solution. In this work, we consider a vertical and heterogeneous multi-access edge computing system. In the system, the RRHs are deployed for providing wireless access for the users and the edge node with computing capability can process the computation requests from the users. With the objective to minimize the total energy consumption for processing the computation task, a joint radio resource allocation and offloading decision optimization problem is presented under the explicit consideration of capacity constraints of fronthaul and backhaul links. Due to the nonconvexity of the formulated problem, we divide the original problem into several sub-problems and address them accordingly to find the optimal solution. Extensive simulation studies are conducted and illustrated to evaluate the advantages of the proposed scheme.
14:30 - 14:40The Learning Stimulated Sensing-Transmission Coordination via Age of Updates in Distributed UAV Swarm
Zhenhua Cui, Tao Yang, Xiaofeng Wu, Chuntao Li, Chongfa Wang, Bo Hu.
        We consider an edge computing framework for online distributed learning in UAV swarm, which allows swarm to collect data and train machine learning (ML) models over the air. Usually, UAVs are used as sensors to collect and transmit data to ground for further processing. However, the overhead for raw data transmission are becoming unaffordable as the task gets complex and the timeliness gets increasingly rigorous. Therefore, We have proposed a new distributed online learning scheme to allow each UAV collect data locally as well as perform ML model training onboard. We have theoretically proved the convergence of the ML model to be trained, and the performance gap between central training method and proposed scheme is analyzed. Furthermore, we have bridged the sensing and transmission via the definition of importance of each UAV based on its contribution in training, where we extend the widely-used timeliness metric Age of Information (AoI) to Age of Updates (AoU), and thus the data freshness and data value in training process are combined together. The performance of the proposed distributed learning scheme is validated, and the difference between AoI and AoU are compared via simulations.
15:00 - 16:00
Special Session 7 : Optimal Resource Allocation for Interference Limited Wireless Networks
Chair: Philippe Ciblat (Telecom Paris, ).
15:00 - 15:10Analysis of Multi-Messages Retransmission Schemes
Alaa Khreis, Francesca Bassi, Philippe Ciblat, Pierre Duhamel.
        Hybrid Automatic ReQuest (HARQ) protocol enables reliable communications in wireless systems. Usually, several parallel streams are sent in successive timeslots following a time-sharing approach. Recently, multi-layer HARQ has been proposed by superposing packets within a timeslot. In this paper, we evaluate the potential of this multi-layer HARQ by playing with some design parameters. We show that a gain in throughput is only obtained at mid-Signal-to-Noise Ratio (SNR).
15:10 - 15:20On the Sum Rate of MISO Rate Splitting with Spatial Randomness
Eleni Demarchou, Constantinos Psomas, Ioannis Krikidis.
        Efficient and intelligently designed multiple access schemes constitute a promising technology for achieving massive connectivity, required by the forthcoming fifth generation and beyond networks. In this work, we investigate the performance of the sophisticated rate splitting (RS) scheme for a multiple-input single-output broadcast channel with two receivers. We consider a distance disparity among the receivers and incorporate a simple precoding which reveals the gains of RS. By taking into account spatial randomness, we provide closed form expressions for the coverage probabilities of each receiver and derive the average sum rate achieved with the employment of RS. We present numerical results that validate our analysis and show that RS brings significant performance gains compared to the well-known non-orthogonal multiple access scheme, while it consists of a general and more flexible scheme.
15:20 - 15:30Achieving SWIPT Through Differential Permutation-Based Coding Intelligent Reflecting Surface
Baptiste Cavarec, Boules Mouris, Ragnar Thobaben, Mats Bengtsson.
        In this paper, intelligent reflecting surfaces (IRSs) are exploited for simultaneous wireless information and power transfer. In the considered setup, the IRS, illuminated by a power transmitter, provides power to integrated sensors through energy harvesting while simultaneously transmitting information through differential permutation-based coding. The problem of allocating the IRS elements to either information or power transmission is studied, highlighting the tradeoff between the system throughput and the harvested power. The conducted performance analysis emphasizes the suitability of using IRSs in a SWIPT scenario without the need for cabled links or channel state information.
15:30 - 15:40Latency Constrained Simultaneous Wireless Information and Power Transfer
Dileep Kumar, Onel L. López, Satya Joshi, Antti Tölli.
        This paper studies a power splitting (PS)-based simultaneous wireless information and power transfer (SWIPT) multi-user system. Specifically, an optimization problem is formulated to minimize the average transmit power of the base station (BS) by jointly optimizing the transmit beamformer and receive PS ratios, while meeting user-specific latency and energy harvesting (EH) requirements. We employ the Lyapunov optimization framework and provide a dynamic control algorithm for the time-average problem. The coupled and non-convex constraints are handled via the Successive Convex Approximation (SCA) technique, and a low-complexity iterative algorithm, where each step is computed in closed-form, is proposed by solving a system of Karush-Kuhn-Tucker (KKT) optimality conditions. The numerical results provide insights on the robustness of the proposed design to realize a power-efficient SWIPT system while ensuring latency and EH requirements in a dynamic network.
15:40 - 15:50Joint Scheduling and Throughput Maximization in Self-backhauled Millimeter Wave Cellular Networks
Chao Fang, Charitha Madapatha, Behrooz Makki, Tommy Svensson.
        Integrated access and backhaul (IAB) networks have the potential to provide high data rate in both access and backhaul networks by sharing the same spectrum. Due to the dense deployment of small base stations (SBSs), IAB networks connect SBSs to the core network in a wireless manner without the deployment of high-cost optical fiber. As large spectrum is available in mmWave bands and high data rate is achieved by using directional beamforming, the access and backhaul links can be integrated in the same frequency band while satisfying quality-of-service constraints. In this work, we optimize the scheduling of access and backhaul links such that the minimum throughput of the access links is maximized based on the revised simplex method. By considering a probability based line-of-sight (LOS) and non-line-of-sight (NLOS) path loss model and the antenna array gains, we compare the achievable minimum access throughput of the IAB network with the network with only macro base stations, and study the effect of the network topology and antenna parameters on the achievable minimum throughput. Simulation results show that, for a broad range of parameter settings, the implementation of IAB networks improves the access minimum achievable throughput.
16:00 - 17:00
Keynote by Sergio Barbarossa : Goal-oriented communications: How to be more efficient by transmitting less
Chair: Slawomir Stanczak (Technische Universität Berlin, ).
Abstract: The goal of this talk is to promote a framework for wireless communications that starts by defining the goal of communication, like for instance edge learning with the desired accuracy within a given time constraint, and then identifies the relevant information to be transmitted to achieve the goal. We start from a theoretic formulation based on the information bottleneck and then we move to applications to edge machine learning in a dynamic environment.

Biography: Sergio Barbarossa received his MS and Ph.D. EE degree from the University of Rome "La Sapienza", where he is currently a Full Professor and a Senior Research Fellow of Sapienza School for Advanced Studies (SSAS). He has held visiting positions at the Environmental Research Institute of Michigan ('88), Univ. of Virginia ('95, ‘97), and Univ. of Minnesota ('99). He is an IEEE Fellow and a EURASIP Fellow. He served as an IEEE Distinguished Lecturer and received the IEEE Best Paper Awards from the IEEE Signal Processing Society for the years 2000 and 2014. He received the 2010 Technical Achievements Award from the European Association for Signal Processing (EURASIP) society for his contributions on radar, communication and networks. He has been the scientific coordinator of several EU projects on wireless sensor networks, small cell networks, distributed mobile cloud computing and 5G networks. He is currently involved in the EU/Taiwan H2020 project 5G-Conni aimed at enabling Industry 4.0 using private 5G networks. His research interests include 5G networks, mobile edge computing, machine learning and topological signal processing.
17:00 - 20:00
Tutorial 1 : Wireless Networks Empowered by Reconfigurable Intelligent Surfaces
Alessio Zappone and Marco Di Renzo
Future wireless networks will be as pervasive as the air we breathe, not only connecting us but embracing us through a web of systems that support personal and societal well-being. That is, the ubiquity, speed and low latency of such networks will allow currently disparate devices and services to become a distributed intelligent communications, sensing, and computing platform.

Small cells, massive MIMO, millimeter-wave communications are three fundamental technologies that will spearhead the emergence of 5G wireless networks - Their advantages are undeniable. The question is, however, whether these technologies will be sufficient to meet the requirements of future wireless networks that integrate communications, sensing, and computing in a single platform.

Wireless networks, in addition, are rapidly evolving towards a software-defined design paradigm, where every part of the network can be configured and controlled via software. In this optimization process, however, the wireless environment itself - the medium or channel - is generally assumed uncontrollable and often an impediment to be reckoned with. For example, signal attenuation limits the network connectivity, multi-path propagation results in fading phenomena, reflections and refractions from objects are a source of uncontrollable interference.

Recently, a new concept called reconfigurable intelligent surfaces (RISs) has emerged wherein every environmental object is coated with man-made intelligent surfaces of configurable electromagnetic materials. These materials would contain integrated electronic circuits and software that enable control of the wireless medium. Thus, RISs enable telecommunication operators to sculpt the very medium that comprises the network. With the aid of RISs, wireless networks will not be designed anymore to adapt themselves to the environment, but the environment will become part of the optimization space. As such, RISs have the potential to fundamentally change how wireless networks are designed and usher in that hoped-for wireless future. But, RISs are not currently well-understood.

This tutorial will cover the emerging wireless vision, the enabling technologies, the most recent theoretical and experimental advances, and the most promising applications envisioned for RISs in wireless networks.

Alessio Zappone obtained his Ph.D. degree in electrical engineering in 2011 from the University of Cassino and Southern Lazio, Cassino, Italy. His Ph.D. studies were focused on distributed algorithms for energy-efficient resource allocation in wireless networks. After obtaining his Ph.D. Alessio has been with the Technische Universität Dresden, Germany, managing the project CEMRIN on energy-efficient resource allocation in wireless networks, funded by the German Research Foundation. From 2017 to 2019 he has been the recipient of the H2020 Individual Marie Curie fellowship for experienced researchers BESMART, carried out in the LANEAS group of CentraleSupelec, Paris, France. He is now a tenured professor at the university of Cassino and Southern Lazio, Italy. He was appointed exemplary reviewer for the IEEE T RANSACTIONS ON C OMMUNICATIONS and IEEE T RANSACTIONS ON W IRELESS C OMMUNICATIONS in 2017. Alessio is an IEEE Senior Member, serves as senior area editor for the IEEE S IGNAL P ROCESSING L ETTERS and as guest editor for the IEEE J OURNAL ON S ELECTED A REASON C OMMUNICATIONS (Special Issues on Energy-Efficient Techniques for 5G Wireless Communication Systems and on Wireless Networks Empowered by RIS).

Marco Di Renzo was born in L'Aquila, Italy, in 1978. He received the Laurea (cum laude) and Ph.D. degrees in electrical engineering from the University of L'Aquila, Italy, in 2003 and 2007, respectively, and the Habilitation a Diriger des Recherches (Doctor of Science) degree from University Paris-Sud, France, in 2013. Since 2010, he has been with the French National Center for Scientific Research (CNRS), where he is a CNRS Research Director (CNRS Professor) in the Laboratory of Signals and Systems (L2S) of Paris-Saclay University - CNRS, CentraleSupelec, Univ Paris Sud, Paris, France.

He serves as the Editor-in-Chief of IEEE Communications Letters, and as an Editor of IEEE Transactions on Communications, and IEEE Transactions on Wireless Communications. He is a Distinguished Lecturer of the IEEE Vehicular Technology Society and IEEE Communications Society, and a Senior Member of the IEEE. He is a recipient of several awards, including the 2013 IEEE-COMSOC Best Young Researcher Award for Europe, Middle East and Africa, the 2013 NoE-NEWCOM# Best Paper Award, the 2014-2015 Royal Academy of Engineering Distinguished Visiting Fellowship, the 2015 IEEE Jack
Neubauer Memorial Best System Paper Award, the 2015-2018 CNRS Award for Excellence in Research and Ph.D. Supervision, the 2016 MSCA Global Fellowship (declined), the 2017 SEE-IEEE Alain Glavieux Award, the 2018 IEEE-COMSOC Young Professional in Academia Award, and 8 Best Paper Awards at IEEE conferences (2012 and 2014 IEEE CAMAD, 2013 IEEE VTC-Fall, 2014 IEEE ATC, 2015 IEEE ComManTel, 2017 IEEE SigTelCom, EAI 2018INISCOM, IEEE ICC 2019). He is a highly cited researcher according to Clarivate Analytics (2019).

Day 2 : 07 Sept. 2021

ISWCS agenda

09:00 - 12:00
Tutorial 3 : Communications and Networking in Droplet-based Microfluidics
Werner Haselmayr, Andrea Zanella, and Giacomo Morabito
This tutorial introduces the emerging field of communications and networking in droplet-based microfluidic systems, where tiny volumes of fluids, so-called droplets, are used for communication and/or addressing purposes in microfluidic chips. With this research, an important step towards the next generation of Lab-on-Chip devices is made. The aim of this tutorial is to lower the entry barrier and to attract communications researchers to enter this new exciting field. The tutorial starts with an accessible introduction of the fundamentals of droplet-based microfluidics. Then, we describe various communication aspects, including information encoding and noise models. We present microfluidic switches as the key building block for microfluidic networks and discuss different network topologies. Moreover, we present two promising healthcare applications for microfluidic networks and show the latest experimental results. For example, the world's first text transmission on a microfluidic chip using droplets. The tutorial concludes with a discussion of the most important open problems in this new field and we show the opportunities for communications researchers to contribute to this area. This tutorial is intended for young and experienced researchers, which are interested in an emerging multidisciplinary research area and want to take the opportunity to look beyond classical communication systems. The topics covered in this tutorial are presented in an accessible way, such that the attendee could immediately start a new project on this topic. No prior knowledge of biology, chemistry or biophysics is required, but the audience should be familiar with basic concepts in communication theory, electrical engineering, and networking.

Werner Haselmayr (S'08-M'13) is an Assistant Professor at the Institute for Communications Engineering and RF Systems, Johannes Kepler University (JKU) Linz, Austria. He received the Ph.D. degree in mechatronics from the same university in 2013. His research interests include the design and analysis of synthetic molecular communication systems and communications and networking in droplet-based microfluidic systems. He is one of the heads of a multidisciplinary group that aims to model, design, and analyze droplet-based microfluidic systems as well as to develop simulation tools and perform physical experiments for such systems. He has given several invited talks and tutorials on various aspects of droplet-based communications and networking. He has authored 2 book chapters and more than 40 paper, appeared in top-level international peer-reviewed journals and conference proceedings. Moreover, he co-organized the 4th Workshop on Molecular Communications 2019, which was held at JKU Linz. Currently, he serves as Associate Editor for the IEEE Transactions on Molecular, Biological, and Multi-Scale Communications.

Andrea Zanella is Full Professor at the Department of Information Engineering (DEI), University of Padova (Italy). He received the Laurea degree in Computer Engineering in 1998 from the same University. In 2000, he was visiting scholar at the Department of Computer Science of the University of California, Los Angeles (UCLA). In 2001, he got a PhD degree in Electronic and Telecommunications Engineering from the University of Padova. Andrea Zanella is one of the coordinators of the SIGnals and NETworking (SIGNET) research lab. His long-established research activities are in the fields of protocol design, optimization, and performance evaluation of wired and wireless networks. He is Technical Area Editor of the IEEE Internet of Things Journal, and Associate Editor of the IEEE Transactions on Cognitive Communications and Networking, IEEE Communications Surveys and Tutorials, and the Digital Communications and Networks (DCN).

Giacomo Morabito received the laurea degree in Electrical Engineering and the PhD in Electrical, Computer and Telecommunications Engineering from the Istituto di Informatica e Telecomunicazioni, University of Catania , Catania (Italy), in 1996 and 2000, respectively. From November 1999 to April 2001, he was with the Broadband and Wireless Networking Laboratory of the Georgia Institute of Technology as a Research Engineer. Since April 2001 he is with the Dipartimento di Ingegneria Elettrica Elettronica e Informatica of the University of Catania where he is currently full professor of Telecommunications. Giacomo Morabito has been founder and steering committee member of the ACM ICN conference, the general chair of ACM Nanocom 2016 and IFIP Med-Hoc-Net 2006, technical program chair of Med-Hoc-Net 2004, TIWDC 2009, ACM SIGCOMM-ICN 2011 and ICOIN 2018 and tutorial chair of IEEE EWSN 2005. He has a long experience in delivering tutorials at conferences and workshops. His research interests include Internet of Things, microfluidic and molecular networks.
13:00 - 16:00
Tutorial 5 : Grant-Free Access for Massive Machine Type Communications and the Internet of Things
Federico Clazzer and Andrea Munari
Major changes have to be applied to medium sharing policies of modern wireless systems to account for the sporadic and uncoordinated nature of the arising machine-to-machine (M2M) and Internet of Things (IoT) paradigm. Classical scheduling-based approaches, although beneficial in avoiding multi-access interference, are particularly impacted by the presence of overhead required to indicate the resources granted to the users. On the other hand, grant-free medium access policies for delivering small data packets have been shown to be undoubtedly flexible in accommodating the sporadic transmission of very large population of terminals in a resource- and energy-efficient way. The goal of the tutorial is to present and thoughtfully review the most recent advances in grant-free medium access policies for massive machine type communications. In particular, after a brief introduction of the most relevant use cases, the tutorial will cover some of the medium access policies currently adopted in license-free and licensed systems, e.g. LoRaWAN, SigFox and NB-IoT. We will highlight the key features and evaluate the advantages and disadvantages. The core of the tutorial will then be dedicated to the presentation of grant-free modern random access solutions. Two main classes are identified, i.e. graph-based random access and compressive sensing-based random access. While to the first belong also more mature solutions already adopted in communication standards (e.g., DVB-RCS2), the second collects the most recent proposals in the field. We then conclude by touching on the use of receiver diversity for grant-free access, having in mind the relevant use cases of heterogeneous networks and satellite mega-constellations.

Federico Clazzer received the M.S. and the Ph.D. degrees in electrical and telecommunications engineering from the University of Genova (Italy) in 2012 and 2017, respectively. Since 2012 he is with the Institute of Communications and Navigation at the German Aerospace Center (DLR), working on medium access protocols for satellite networks, with particular emphasis to the machine-to-machine and Internet of Things scenarios. In 2014, 2015 and 2016 he visited the Chinese University of Hong Kong and in particular the Institute of Network Coding, working on physical layer network coding and medium access protocols. In 2017 he visited the University of Newcastle and the University of Sydney to work on the design of error correcting codes for asynchronous random access protocols. His main research interests include satellite communications, random access techniques, signal processing for the multiple access channel and game theory. He served on the Technical Program Committee at several IEEE International Conferences and has been appointed as 2016 Exemplary Reviewer for IEEE TRANSACTIONS ON COMMUNICATIONS and 2019 Exemplary Reviewer for IEEE WIRELESS COMMUNICATIONS LETTERS. He served on the Organizing Committee (as co-chair) of the Workshop on Small Data Networks at IEEE VTC Fall 2019.

Andrea Munari received the Laurea degree (M.S. equivalent) summa cum laude and the Ph.D. in Telecommunications Engineering from the University of Padova, Italy, in 2006 and 2010, respectively. In 2007 he joined IBM Research in Zurich, Switzerland, working on the design, analysis and implementation of energy efficient routing protocols for wireless sensor networks. In 2010 he was a research fellow at the University of Padova, and in 2011 he joined the Corp. R&D division of Qualcomm Inc. in San Diego, California, for a post-doctoral internship focused on network coding techniques for LTE cellular scenarios. Currently, he is with the Institute of Communications and Navigation of the German Aerospace Center (DLR). His main research interests include design and modelling of medium access techniques, satellite and in-band full-duplex communications as well as radar networks. From 2014 to 2018 he held a senior researcher and lecturer position at the Institute of Networked Systems of RTWH Aachen University. He served on the Technical Program Committee at several IEEE International Conferences and on the Organizing Committee (as co-chair) of the IEEE ICC'14, ICC'15, and ICC'16 Workshop on Massive Uncoordinated Access Protocols, of the special session on Small Data Networks at IEEE PIMRC 2018, and as Co-Chair of the IEEE VTC-Fall 2019 Workshop on Small Data Networks. He is a Senior Member of IEEE and Topic Editor for the MDPI Sensors journal.
16:00 - 17:00
Keynote by H. Vincent Poor : Towards 6G Wireless Communication Networks: Vision, Enabling Technologies, and New Paradigm Shifts
Chair: Petar Popovski (Aalborg University, ).
Abstract: Fifth generation (5G) wireless communication networks are being deployed worldwide and more capabilities are in the process of being standardized, such as massive connectivity, ultra-reliability, and low latency. However, 5G will not meet all requirements of the future, and sixth generation (6G) wireless networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, greater intelligence and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architectures, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. One vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle (UAV) communication networks, thus achieving a space-air-ground-sea integrated communication networks. Multiple spectra will be exploited to further increase data rates and connection density, including the sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical frequency bands. Third, facing the very large datasets generated by heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of AI-related technologies. And, fourth, network security will have to be strengthened when developing 6G networks. This talk will review recent advances and future trends in these four aspects.

Biography: H. Vincent Poor is the Michael Henry Strater University Professor at Princeton University. His interests are in the areas of information theory, signal processing and machine learning, and their applications in wireless networks, energy systems and related fields. He is a member of the U.S. National Academy of Engineering and the U.S. National Academy of Sciences, and is a foreign member of the Chinese Academy of Sciences, the Royal Society and other national and international academies. Recent recognition of his work includes the 2017 IEEE Alexander Graham Bell Medal, and honorary doctorates from a number of universities in Asia, Europe and North America.
17:00 - 20:00
Tutorial 2 : Privacy, Storage, and Security with Physical Unclonable Functions (PUFs)
Onur Günlü and Rafael F. Schaefer
This tutorial addresses security and privacy problems for digital communication devices including Internet-of-Things (IoT), Internet-of-Vehicles (IoV), and 5G/6G devices. A physical unclonable function (PUF) is a promising universal solution for local security and privacy. Low-complexity signal processing algorithms, such as the transform-coding algorithm, are illustrated to make the information-theoretic analysis tractable and to motivate a noisy (remote) PUF source model. The optimal trade-offs between the secret-key, privacy-leakage, and storage rates for multiple measurements of hidden PUFs are characterized to illustrate the diversity and multiplexing gains. The optimal and low-complexity code constructions for secret-key agreement with PUFs are discussed, including tail-biting convolutional codes, polar codes, and polar subcodes. The gains from cost-constrained controllable PUF measurements are briefly illustrated to motivate various extensions, including post-Shannon communication with PUFs.

Onur Günlü (S'10 - M'18) received the B.Sc. degree (with high distinction) in Electrical and Electronics Engineering from Bilkent University, Turkey in 2011; M.Sc. (with high distinction) and Dr.-Ing. (Ph.D. equivalent) degrees in Communications Engineering both from the Technical University of Munich (TUM), Germany in October 2013 and November 2018, respectively. He was a Working Student in the Communication Systems division of Intel Mobile Communications (IMC), now Apple Inc., in Munich, Germany during November 2012 - March 2013. He worked as a Research and Teaching Assistant at TUM between February 2014 - May 2019. He was a Visiting Researcher at the Information and Communication Theory (ICT) Lab of TU Eindhoven, The Netherlands during February 2018 - March 2018 funded by a European Union (EU) project. He was a Research Associate and Dozent at TU Berlin, Germany between June 2019 - September 2020, and has been a Research Group Leader and Dozent at TU Berlin since October 2020. He has been a Brain City Berlin Ambassador since June 2020. His research interests include information theoretic privacy and security, coding theory, statistical signal processing for biometrics and physical unclonable functions (PUFs), federated learning (FL) with differential privacy (DP) and information privacy guarantees, and doubly-exponential secure identification via channels. Among his publications is the recent book Key Agreement with Physical Unclonable Functions and Biometric Identifiers (Dr. Hut Verlag, 2019). He is currently an Associate Editor of the EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING and MDPI ENTROPY Journal, a Guest Editor of the IEEE JOURNAL ON SELECTED AREAS IN INFORMATION THEORY, and a Reviewer Board Member of the MDPI COMPUTER and INFORMATION Journals.

Rafael F. Schaefer received the Dipl.-Ing. degree in electrical engineering and computer science from the Technische Universität Berlin, Germany, in 2007, and the Dr.-Ing. degree in electrical engineering from the Technische Universität München, Germany, in 2012. From 2013 to 2015, he was a Post-Doctoral Research Fellow with Princeton University. From 2015 to 2020, he was an Assistant Professor with the Technische Universität Berlin. Since 2021, he has been a Full Professor with Universität Siegen. Among his publications is the recent book Information Theoretic Security and Privacy of Information Systems (Cambridge University Press, 2017). He was a recipient of the VDE Johann-Philipp-Reis Prize in 2013. He received the best paper award of the German Information Technology Society (ITG-Preis) in 2016. He was one of the exemplary reviewers of the IEEE Communication Letters in 2013. He is currently an Associate Editor of the IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY and of the IEEE TRANSACTIONS ON COMMUNICATIONS. He is a Member of the IEEE Information Forensics and Security Technical Committee.

5th International Workshop on Optical Wireless Communications (IWOW) 2021 agenda

09:00 - 09:15
5th IWOW 2021 - Opening Session
Chair: Mohammad-Ali Khalighi (Ecole Centrale Marseille, ).
Opening Session for the 5th IWOW 2021 at 17th ISWSC 2021.
09:15 - 09:55
5th IWOW 2021 - Invited Speaker session 1 - by Prof Volker Jungnickel, Fraunhofer HHI, Berlin, Germany.
Chair: Mohammad-Ali Khalighi (Ecole Centrale Marseille, ).
Invited speaker session 1 at 5th International Workshop on Optical Wireless Communications (IWOW), at 17th ISWCS 2021.

Title: Standards Evolution for OWC

Keynote invited speaker: Prof Volker Jungnickel, Fraunhofer HHI, Berlin, Germany

Optical Wireless Communications (OWC) is an emerging mobile technology with much smaller cell sizes compared to radio. OWC it is ideal for network densification for adding "personal" small cells. OWC demonstrated its advantages in many applications, including home, office, industrial, medical and underwater, but has no killer application yet. Several new standards aim to address the potential new market for OWC and reach high volumes in different ways. ITU-T G.9991 and IEEE P802.11bb both reuse existing standards defined for other media, like power-/phone-line/coax and radio, respectively. Both keep the initial costs low by reusing existing chipsets, but capabilities and limits remain the same. The IEEE P802.15.13 project aims at unprecedented features for the industrial IoT, like high reliability, low latency, high data rates and low energy. The talk will give an overview on these standards and their current evolution.

Volker Jungnickel (Member, IEEE) received the Doctoral degree from Humboldt University, Berlin, Germany, in 1995, and the Habilitation degree in physics and communications engineering from the Technical University of Berlin, Berlin, Germany, 2015, respectively. In 1997, he joined Fraunhofer HHI, Berlin, Germany, working on optical wireless communication, adaptive multiple antenna techniques in mobile networks, and fixed optical access infrastructures. He is with the Technical University of Berlin, Berlin, Germany, as Privatdozent teaching courses on advanced wireless communications and supervising master's and Ph.D. thesis. He is the Chair of IEEE P802.15.13 Task Group on multi-Gbit/s optical wireless communications and a Technical Editor of the IEEE P802.11bb Task Group on light communications.
10:00 - 11:00
5th IWOW 2021 - Session 1 - Regular papers
Chair: Stanislav Zvanovec (Czech Technical University in Prague, ).
10:00 - 10:10Reinforcement Learning Adaptive Vertical Handover Scheme for Hybrid VLC-IR Networks in Ship Cabins
Jingtao Wu, Dahai Han, Min Zhang, Zabih Ghassemlooy.
        We propose an adaptive seamless vertical handover scheme for hybrid visible light communication-infrared (VLC-IR) networks in ship cabins based on Sarsa-lambda reinforcement learning algorithm. Compared with the Q-learning and Sarsa, the proposed algorithm surpasses the average downlink data rate by 13% and 14%, respectively. Moreover, the proposed algorithm outperforms the average downlink data rate of immediate handover and dwell handover schemes by 57% and 22%, respectively when the user device movement speed is 1 m/s.
10:10 - 10:20Transmit Precoding for Physical Layer Security of MIMO-NOMA-Based Visible Light Communications
Nuğman Su, Erdal Panayirci, Mutlu Koca, Harald Haas.
        We consider the physical layer security (PLS) of non-orthogonal multiple access (NOMA) enabled multiple-input multiple-output (MIMO) visible light communication systems in the presence of a passive eavesdropper (Eve). In order to disrupt the decoding process at Eve, we propose a novel precoding scheme reinforced with random constellation coding. Multiple legitimate users (Bobs) will be served simultaneously using NOMA. For the proposed precoder design, we exploit the slow-fading characteristics of the visible light channel so that the transmitted symbols are successfully decoded at Bob, while Eve suffers from very high bit error ratios (BERs) due to precoding-induced jamming. Via computer simulations, we show that Bob can successfully decode their own information in various user configurations and receiver diversities. It is also shown that the BER at Eve's side is increased to the 0.5-level for similar and the asymmetrical positioning of Bob with respect to the transmitter, thus PLS is ensured by the proposed precoding technique.
10:20 - 10:30Energy Efficiency Maximization in Cooperative Hybrid VLC/RF Networks with NOMA
Konstantinos Rallis, Vasilis Papanikolaou, Panagiotis Diamantoulakis, Mohammad-Ali Khalighi, George Karagiannidis.
        In this paper, a cooperative hybrid visible light communications (VLC)/radio frequency (RF) network that employs non-orthogonal multiple access (NOMA) is investigated. More specifically, the resource allocation and the operating mode of the system is optimized to maximize a weighted energy efficiency metric, taking into accounts the particularities of the hybrid network. The resulting optimization problem is efficiently tackled with the use of Dinkelbach's algorithm and difference of convex programming. Using this solution, a deep neural network (DNN) is trained to find the operation mode and alleviate the computational cost of the overall problem leading to a close solution to the optimal. Finally, the effectiveness of the proposed setup is presented via Monte Carlo simulation results.
10:30 - 10:40Experimental investigation of an adaptive V2V optical camera communications system
Negar Shirvani Kordavani, Asghar Gholami, Ehsan Hamidnejad, Negar Masjedi Esfahani, Zabih Ghassemlooy.
        Research in the field of optical camera communications (OCC) has increased recently. This paper present the results of the experimental investigation of an adaptive OCC for vehicle-to-vehicle communications. The system comprises light emitting diode-based taillights and a mobile phone camera used as the transmitter and the receiver, respectively. We experimentally investigate the performance of the proposed system with adaptive thresholding and show that under different ambient-light conditions there is a marked improvement in the bit error rate performance.
10:40 - 10:50Performance Analysis and Optimization of Cascaded I2V and V2V VLC Links
Hossien Eldeeb, Mohammed Elamassie, Murat Uysal.
        In smart transportation systems, the infrastructures such as traffic lights are expected to transmit different safety messages according to the receptors (i.e., vehicle, pedestrian, platoon, etc.). The focus of this study is the infrastructure-toplatooning scenario where the lead-vehicle receives the signal from the traffic light (I2V), decodes, and re-transmits it again using its taillights to the following vehicle (V2V). Normally, the lead-vehicle also communicates with nearby vehicles to avoid the crashes and/or sharing the primary public safety information. Therefore, to enable the infrastructures and the vehicle to efficiently perform their multi-connections, it becomes necessary to know what the optimum power for the I2V and V2V links is. In this paper, we answer this question by realistic modeling of the hybrid I2V-V2V system. We first propose a new I2V path loss model considering the inherent characteristics of commercial traffic lights. For V2V link, we utilize a recent path loss model obtained with the same approach and with commercial taillights as the transmitters. Then, we obtain the SNR of both I2V and V2V links which are moreover used to derive the optimal power allocations that minimize the end-to-end BER of the I2V-V2V system. The effect of system parameters such as I2V and V2V distances, total transmit power, and system bandwidth on the BER is further investigated.
10:50 - 11:00Visible Light Communication-Based Outdoor Broadcasting
Hossien Eldeeb, Murat Uysal.
        In this paper, we explore visible light communication (VLC) as a wireless connectivity solution to enable outdoor broadcasting for public safety systems. Unlike indoor VLC broadcasting systems which build upon LED ceiling luminaries, outdoor VLC systems use ubiquitous streetlights as transmitters. Outdoor lights with specific illumination requirements have radiation patterns which differ from their indoor counterparts. In addition, the effects of weather conditions, orientation of the user equipment, and sunlight should be considered for outdoor VLC broadcasting systems. Taking into account such fundamental differences imposed by the outdoor medium and lightning infrastructure, we investigate the system performance for the links between streetlight-to-pedestrian (S2P) and streetlight-to-vehicle (S2V).
11:00 - 12:00
5th IWOW 2021 - Session 2 - Regular papers
Chair: Joaquin Perez (Universitat de Valencia, ).
11:00 - 11:10A VLC-based Footprinting Localization Algorithm for Internet of Underwater Things in 6G networks
Anna Maria Vegni, Marwan Hammouda, Valeria Loscrí.
        In the upcoming advent of 6G networks, underwater communications are expected to play a relevant role in the context of overlapping hybrid wireless networks, following a multi-layer architecture i.e., aerial-ground-underwater. The concept of Internet of Underwater Things defines different communication and networking technologies, as well as positioning and tracking services, suitable for harsh underwater scenarios. In this paper, we present a footprinting localization algorithm based on optical wireless signals in the visible range. The proposed technique is based on a hybrid Radio Frequency (RF) and Visible Light Communication (VLC) network architecture, where a central RF sensor node holds an environment channel gain map i.e., database, that is exploited for localization estimation computation. A recursive localization algorithm allows to estimate user positions with centimeter-based accuracy, in case of different turbidity scenarios.
11:10 - 11:20Experimental Evaluation of a Hermite Function-Based Multicarrier Scheme for VLC
Carlos Guerra-Yánez, Stanislav Zvanovec, Zabih Ghassemlooy.
        The use of a wide variety of modulation schemes for visible light communications (VLC) systems has been proposed since the birth of this field, and each of these modulations address some specifications that must be met by the system. Modified Hermite pulses define a family of functions with desirable characteristics regarding their orthogonality and time-frequency behaviour that has been used previously in radio-frequency and ultra wideband communications, ranging and VLC applications. In this work, the first experimental evaluation, to the best of authors' knowledge, of an Hermite function-based multicarrier scheme for VLC is presented and compared with simulations carried out under similar conditions. The results show that, for low modulation orders, the system is able to detect signals even below the noise floor.
11:20 - 11:30Multiband IFoF signal transmission based on DML with local photonic 40 GHz up conversion
Luis Vallejo, Beatriz Ortega, Dong-Nhat Nguyen, Jan Bohata, Jose Mora, Stanislav Zvanovec.
        Multiband data signal transmission using intermediate frequency over fiber (IFoF) is proposed and demonstrated with local photonic millimetre wave (mmW) generation. The proposed scheme is based on a low cost directly-modulated laser (DML) and Mach-Zehnder modulator (MZM) biased at a null point for optical carrier suppression to realize optical frequency multiplication (OFM). Transmission of 4- and 64-quadrature amplitude modulation (QAM) signals providing data rates of 3 and 1.5 Gbps, respectively, over 25 km standard single mode fiber (SSMF) are demonstrated and signals are delivered at 40 GHz to be radiated by the remote radio heads (RRHs). As a proof of concept, also multiband signal of various modulation formats and bandwidths have been transmitted successfully along 25 km fiber link and delivered in the mmW band. Quality signal assessment by error vector magnitude (EVM) measurement at mmW bands is demonstrated and an estimation of the optical sensitivity of the system is provided.
11:30 - 11:40Reliability Analysis of Slotted Aloha with Capture for an OWC-based IoT system
Milica Petkovic, Tijana Devaja, Dejan Vukobratović, Francisco J. Escribano, Čedomir Stefanović.
        In this article, we consider a random access scheme for an indoor Internet of Things (IoT) framework that uses optical wireless communication (OWC). We focus on a Slotted ALOHA (SA)-based solution where a number of OWC IoT users contend to send data to a central OWC receiver. In any given slot, and for a randomly selected active user, we consider the reliability of decoding the user's data packet at the receiver. This is done by deriving the signal-to-noise-and-interference-ratio (SINR) statistics from a randomly chosen user and evaluating the probability that the user's SINR is below a given threshold. By placing our analysis in the context of an indoor OWC IoT uplink setup, and employing the standard OWC channel model, we investigate the trade-offs between the reliability and the OWC system parameters such as the cell area or the transmitter's semi-angle. We obtain valuable insights into the design of an SA-based random access solution for a typical indoor OWC cell.
11:40 - 11:50Vehicular VLC Channel Model for a Low-Beam Headlight Transmitter
Bassam Aly, Mohammed Elamassie, Murat Uysal.
        The availability of LED-based headlights and taillights allows visible light communication (VLC) to be considered as a powerful wireless access technology for vehicle-to-vehicle (V2V) communications. A crucial system design concern is modeling a realistic vehicular VLC channel which is verified through measurements. In this paper, we experimentally measure the optical channel for V2V considering a low beam headlight and propose a closed-form path loss expression through data fitting. We further calculate the achievable system capacity that can be supported with such a VLC transmitter.
11:50 - 12:00LiFi based Positioning for Indoor Scenarios
Sepideh Mohammadi Kouhini, Ziyan Ma, Christoph Kottke, Sreelal Maravanchery Mana, Ronald Freund, Volker Jungnickel.
        An indoor positioning system integrated with wireless communication is an essential tool for future Internet of Things applications. This paper presents a time-of-flight-based positioning approach based on networked optical wireless communication, which is also known as LiFi. Our proposed system is based on the ITU-T G.9991 standard and enables positioning besides communication using the existing physical layer protocol. In this paper, we introduce this approach and evaluate the positioning performance in a conference room. Results show that the physical layer frame in G999.1 enables ranging with an accuracy of below 5 centimeters, besides enabling wireless communications. Moreover, we show that our LiFi system is able to cover a large area suitable for realistic indoor scenarios.
13:00 - 13:40
5th IWOW 2021 - Invited Speaker session 2 by Dr Valeria Loscrì, Inria Lille-Nord Europe, France
Chair: Zabih Ghassemlooy (Northumbria University, ).
Invited speaker session 2 - at 5th International Workshop on Optical Wireless Communications (IWOW), at 17th ISWCS 2021.

Title: Software Defined Approaches for Adaptive VLC Systems

Keynote invited speaker: Dr Valeria Loscrì, Inria Lille-Nord Europe, France

Visible light communication (VLC) builds on the dual use of lightening infrastructure for communication. Even though the great potential and advantages of VLC as communication paradigm are well known, some important open issues still need to be addressed in order to rely on it as a robust communication system and makes VLC a more pervasive and ubiquitous communication technology.
First of all, the impact of external interference and its rapid change demand high reactive systems, able to adapt their configuration to properly address these changes. For these reasons, research community is more and more focusing on context aware adaptive approaches. The Software Defined (SD) paradigm, meant as the realization of the main operations (e.g., modulation, filter, etc.) via software, is considered a viable enabling technology to design high performant and responsive VLC systems, adapting in real time to the context. The talk will mostly discuss two specific examples of Software Defined approach as adaptive intelligent approach for synchronization and adaptive full-duplex architecture, and will go across different potential applications of the SD paradigm as key enabling approach for VLC systems.

Valeria Loscrí has been a permanent researcher of the FUN Team at Inria Lille-Nord Europe since October 2013. From December 2006 to September 2013, she was research fellow in the TITAN Lab of the University of Calabria, Italy. She received her M.Sc. and Ph.D. degrees in computer science in 2003 and 2007, respectively, from the University of Calabria. Her research interests focus on heterogeneous communication technologies and cooperation of heterogeneous devices. She has been involved in the activities of several European Projects (FP7 EU project VITAL, the FP6 EU project MASCOT, and so on), and Italian and French projects. She is on the editorial board of the Elsevier ComNet, JNCA, and IEEE Transactions on Nanobioscience. She has been a guest editor for a Special Issue in Elsevier Ad Hoc Networks and she has been an editor of the book Vehicular Social Networks published by CRC Taylor & Francis Group, in March 2017, and Management of Cyber Physical Objects in the Future Internet of Things published by Springer. Since 2015 she has been a member of the Committee for Technological Development at Inria Lille-Nord Europe. Since 2016, she has been Scientific European Responsible for Inria Lille-Nord Europe.
13:40 - 14:40
5th IWOW 2021 - Session 3 - Regular papers
Chair: Anna Maria Vegni (Roma Tre University, ).
13:40 - 13:50Influence of optical axons on the synaptic weights
Mircea Hulea, Zabih Ghassemlooy, Othman Younus, Sujan Rajbhandari.
        Hardware implementation of the spiking neural networks benefits from parallel processing and transmission of the data. When the neural areas are distanced or are in relative motion, the optical wireless connections represent a reliable alternative to the hard-wiring. Recent research shows that optical axons (OAs) can be successfully used in optical neural networks (NNs) because of the increased tolerance to the optical signal fading to the network activity. This work experimentally evaluates the influence of the optical signal fluctuations caused by the variation of the optical link length and misalignment on the transmitted weights. When the activation threshold of the neuron is reached, the OA triggers the electronic synapses that generate spikes of variable duration according to the synaptic weights. The results show that the duration of the transmitted spike is not affected by the changes in the optical signal intensity when the optical path varies from 0.05 to 1.90 m and the optical misalignment is below 60°. Hence, the OAs can be used to connect simple spiking neural networks (SNNs) such as neuromorphic sensors and the main neural control units or to interconnect high complexity neural areas that control humanoid robots.
13:50 - 14:00Performance Analysis of the FBMC Modulation Format in Optical Fiber and Wireless Communications
Rastislav Róka, Caslav Stefanovic, Máximo Morales-Céspedes, Ana Garcia Armada.
        The FBMC is among the currently most researched techniques for signal processing and is explored here for passive optical access networks. This paper presents a performance analysis of the FBMC modulation format for applying in optical fiber and wireless communications. For analyzing, we realized simulation models that are based on well-known characteristics of the optical transmission medium and the free space environment that can describe mutual relations between optical signals and environmental influences. The FBMC model can be consequently applied for a purpose of advanced simulations performed in the complete optical transmission path. The results suggest that the FBMC format can be utilized for reliable optical fiber and wireless communication systems.
14:00 - 14:10Achievable rate of LED-based distributed MIMO OWC systems under a per-LED power constraint
Thiago Elias Cunha, Jean-Paul M. G. Linnartz, Xiong Deng.
        Multiple-input multiple-output (MIMO) systems have been widely studied for improving throughput and robustness of optical wireless communication (OWC) systems. Indeed, with MIMO, the likelihood of simultaneous interruption of all optical beams is greatly reduced. For throughput improvement, many power loading strategies are obtained for a total power constraint while allowing power to be freely exchanged among light-emitting diodes (LEDs). In scenarios with unequal distances between LEDs and the user terminal, more power is allocated to the LED that has a better channel than to others. In practice, every optical front-end has its own power limitation and a per-LED power constraint is more meaningful than a total power constraint. This paper studies to what extent this has an impact on the performance of LED-based distributed MIMO (D-MIMO) OWC links. We formulate the achievable rate optimization problem for both cases, when the total power is constrained or when under a per-LED power constraint. Results show that, the achievable rate under a per-LED power constraint is lower than under a total power constraint, but it is higher than if the power is uniformly spread over the entire bandwidth. It also allows for transmit power saving, at a cost of higher computational complexity. In addition, under a per-LED power constraint, LEDs with better channel condition tends to use a modulation bandwidth far above the 3-dB bandwidth.
14:10 - 14:20The Evaluation of an RoF System Using FSO and a Seamless Antenna Link for the 5G RAN
Jan Bohata, Dong-Nhat Nguyen, Zabih Ghassemlooy, Beatriz Ortega, Stanislav Zvanovec.
        The fifth generation of mobile network (5G) places increased demands on the communication infrastructure, which should be formed in particular by optical networks. Moreover, the use of millimeter-wave (mmW) frequency bands contributes to higher degree of the radio frequency and optical systems convergence. Therefore, we show in this paper the comparison between two wireless seamless connections as part of the radio over fiber (RoF) system, namely free space optical link and mmW wireless link operating at the 5G mmW frequency bands of 27 and 39 GHz. We also demonstrate the impact of including a 10 km of optical fiber to a RoF system with a seamless antenna connection at 27 GHz.
14:20 - 14:30Lane-cross Detection using Optical Camera-based Road-to-Vehicle Communications
Neelima Devulapalli, Vicente Matus, Elizabeth Eso, Zabih Ghassemlooy, Rafael Perez.
        Optical camera communications (OCC) is a pragmatic version of visible light communication (VLC), based on a smart device camera that allows more straightforward implementation of various services in smart devices. OCC provides unique opportunities for establishing short-range VLC links by using a camera as the optical receiver. Camera/image sensor-based optical wireless communication technologies are being widely used in areas like Internet-of-things, indoor localization, motion capture and intelligent transportation systems. In recent times, cameras usage in vehicles has been increased to monitor speed, collision avoidance, object recognition, and traffic signs. This paper presents simulation-based results of lane cross detection using OCC, and it investigates the theoretical and practical aspects of OCC-based road-to-vehicle communications. A geometrical model to estimate the minimum distance at which there is a chance to cross the lane and the distance at which the driver receives an alert signal to avoid accidents, along with the simulation results, is presented in this paper.
14:30 - 14:40Impact of Receiver Orientation on OLED-based Visible-Light D2D Communications
Zahra Nazari Chaleshtori, Stanislav Zvanovec, Zabih Ghassemlooy, Oussama Haddad, Mohammad-Ali Khalighi.
        The use of organic light emitting diodes (OLEDs) is being growing in public places, mobile phones, and wearable smartwatches and computers, which facilitate simultaneous illumination, display, and data communications. Therefore, there is a high demand to model the OLED-based visible light communications (VLC) channel in device-to-device (D2D) communications. This paper proposes D2D communications where the information data is transmitted via the smartphone's display pixels and received using the built-in cameras of another smartphone. The impact of the receiver orientation on the channel characteristics is investigated, where two static users face each other and the receiver is intentionally oriented towards the transmitter. It is shown that, in an empty room, the range of delay spreads are around 6 to 7.5 ns and 6 to 10 ns when the distances of the transmitter from the wall are 1.5 and 7.5 m, respectively. Furthermore, in a furnished room, there is a drop in the delay spread at the cost of increased optical path loss compared to the empty room.
13:40 - 14:40
5th IWOW 2021 - Session 4 - Regular papers
Chair: Luis Alves (DETI, Universidade of Aveiro, Instituto de Telecomunicações, ).
13:40 - 13:52Performance Analysis of N-Fisher-Snedecor F Fading and Its Application to N-Hop FSO Communications
Caslav Stefanovic, Máximo Morales-Céspedes, Rastislav Róka, Ana Garcia Armada.
        The Fisher-Snedecor F distribution has been recently proposed as an experimentally verified and tractable turbulence induced fading model (TIFM) for free space optical (FSO) communications. This paper provides outage probability (OP) and higher-order (HO) performance analysis of the product of N independent but not identically distributed (i.n.i.d) Fisher-Snedecor F random variates (RVs). Accurate and closed-form (C-F) expressions for cumulative distribution function (CDF), level crossing rate (LCR) and average fade duration (AFD) of N-Fisher-Snedecor F distribution are successfully derived. The general property of a Laplace approximation approach for evaluation of N-folded complex integral-form (I-F) LCR expressions has been applied. The obtained statistical results are directly related to the performance evaluation of N-hop FSO communication links over weak, moderate and strong atmospheric turbulence conditions.
13:52 - 14:04Multiscale Simulation for Visible Light Communication using Perovskite Metasurface
Raphaël Mermet-Lyaudoz, Pierre Combeau, Emmanuel Drouard, Anne Julien-Vergonjanne, Christian Seassal, Hai Son Nguyen, Stéphanie Sahuguède.
        This article presents an original multi-scale simulation approach, enabling to rigorously compute the far-field radiation from emerging halide perovskite light-emitting diodes integrating a metasurface active layer, and subsequently to evaluate its impact on the propagation channel characteristics at the scale of an indoor environment, both in terms of coverage and time dispersion. Our results show that the high versatility of the metasurface design parameters allows to divide the outage probability up to a factor 2 without degrading the time dispersion of the optical channel for a visible light communication scenarios.
14:04 - 14:16Resource allocation in a Quantum Key Distribution Network with LEO and GEO trusted-repeaters
Milo Grillo, Alexis Dowhuszko, Mohammad-Ali Khalighi, Jyri Hämäläinen.
        Quantum Key Distribution (QKD) is a technology that enables the exchange of private encryption keys between two legitimate parties, using protocols that involve quantum mechanics principles. The rate at which secret keys can be exchanged depends on the attenuation that is experienced. Therefore, it is more convenient to replace many terrestrial fiber segments (and repeaters) by just few optical satellite links that would enable flexible global coverage. Then, the satellite nodes can take the role of trusted-relays, forwarding the secret keys from source to destination. However, since the rate at which secret keys can be generated in each quantum link is limited, it is very important to select the intermediate satellite nodes to inter-connect ground stations efficiently. This paper studies the most convenient allocation of resources in a QKD network that combines complementary connectivity services of GEO and LEO satellites. The aim of the centralized routing algorithm is to select the most convenient trusted-relays to forward the secret keys between pairs of ground stations, verifying the constraints that satellite-to-ground and inter-satellite quantum channels have.
14:16 - 14:28Power Allocation Optimization in NOMA-Based Multi-Cell VLC Networks
Mahmoud Eltokhey, Mohammad-Ali Khalighi, Zabih Ghassemlooy.
        The use of visible-light communication (VLC) to complement radio-frequency systems in satisfying the ever increasing user data demands has received particular interest since about two decades. One important issue in VLC networks is to address the multiple-access (MA) requirement. Non-orthogonal MA (NOMA) is a promising technique for multi-cell VLC networks, in particular, due to providing high spectral efficiency. However, its performance is highly impacted by the considered power allocation (PA). In this paper, we propose optimization of PA in NOMA-based VLC networks using particle swarm optimization. The presented results show that the optimized PA offers a higher performance in terms of the network achievable throughput and fairness, compared with non-optimized PA, while offering flexibility in controlling the desired performance criteria.
14:28 - 14:40VLC network topology design for seamless communication in a urban tunnel
Edmundo Torres-Zapata, Victor Guerra, Jose Rabadan, Jose Luna-Rivera, Rafael Perez.
        Visible Light Communications networks are usually based on isolated access points which deals individually with the handover strategy. Basically when a node is detected by an access point the network's protocol upper layers redirect the traffic to the new access point. This strategy cannot be suitable for vehicle communications and different alternatives of handover should be developed. In this paper, a new network architecture is presented including a novel handover scheme based on distributed receivers. This system has been tested for vehicle to infrastructure applications in a tunnel scenario and results show that, in comparison with classical scheme, it demonstrates an upgrade in general performance.
14:45 - 15:35
5th IWOW 2021 - Open forum - "The future of OWC"
Chair: Monica Figueiredo (Polytechnic Institute of Leiria, ); Mohammad-Ali Khalighi (Ecole Centrale Marseille, ); Anna Maria Vegni (Roma Tre University, ).
Open forum session on "The future of OWC" - at 5th International Workshop on Optical Wireless Communications (IWOW), at 17th ISWCS 2021.

This is an open forum for discussion about "The future of optical wireless communications".

The panel is chaired by:

Dr Anna Maria Vegni - Università degli Studi Roma Tre
Italy - Panel Chair
Dr Monica Figueiredo, Polytechnic of Leiria, Portugal - Panel Chair

The panel is formed by:

Dr Victor Guerra, Univ. de Las. Palmas de Gran Canaria, Spain
Dr Afsaneh Maleki
Dr Pedro Fonseca, Univ. de Aveiro, Portugal
Prof Jing He, Hunan University, China
15:40 - 15:50
5th IWOW 2021 - Closing Session
Chair: Zabih Ghassemlooy (Northumbria University, ).
Closing Session for the 5th IWOW 2021 at 17th ISWSC 2021.

Dr Ali M. Khalighi, Chair of NEWFOCUS Cost Action IC19111.

Day 3 : 08 Sept. 2021

09:00 - 10:00
Keynote by Gerhard Kramer : Low-Resolution Precoding for Multi-Antenna Downlink Channels and OFDM
Chair: Eduard Jorswieck (Technische Universität Braunschweig, ).
Abstract: Multi-input, multi-output (MIMO) technology with a large number of base station antennas is a key enabler of high data rates for mobile communications. To keep down cost, one can use a digital approach with constant envelope signaling and low-resolution quantizers, e.g., two to three bits per antenna. This talk reviews low-resolution precoding algorithms for multi-path channels and OFDM, including quantized linear precoding (QLP), relaxed optimization (SQUID, ADMM-based), maximum safety margin (MSM), and quantized coordinate-wise minimization (QCM, MAGIQ). We argue that QCM achieves the highest information rates with the lowest complexity. To compute the rates, an auxiliary channel model is developed for separate (pilot-aided) or joint channel and data estimation. Simulations with standard frequency selective channels (Rayleigh fading, WINNER II) and mixed RF chains (low and high resolution) show that QCM is a promising approach for multi-user MIMO. The talk is based on joint work with Andrei Nedelcu and Fabian Steiner.

Biography: Gerhard Kramer is Senior Vice President for Research and Innovation at the Technical University of Munich (TUM). He joined TUM as Alexander von Humboldt Professor and Chair of Communications Engineering in 2010 after a short stay at the University of Southern California (USC), Los Angeles, CA, from 2009-10. He received the B.Sc. and M.Sc. degrees in electrical engineering from the University of Manitoba in 1991 and 1992, respectively, and the Dr. sc. techn. degree from ETH Zurich in 1998. From 1998 to 2000, he was with Endora Tech AG in Basel, Switzerland, and from 2000 to 2008 he was with the Math Center at Bell Labs in Murray Hill, NJ. His research interests are primarily in information theory and communications theory, with applications to wireless, copper, and optical fiber networks. Gerhard Kramer is an IEEE Fellow and served as the 2013 President of the IEEE Information Theory Society. He is a member of the Bavarian Academy of Sciences and Humanities since 2015.
10:00 - 11:00
Regular Session 3 : mmWave Systems
Chair: Pan Cao (University of Hertfordshire, ).
10:00 - 10:10Multibeam Antenna Modelling and Blockage Impact Mitigation in 5G Millimeter-wave Bands
Hamidou Dembélé, Marie Le Bot, Francois Gallée, Patrice Pajusco.
        This paper discusses a generic approach proposal for modelling multibeam antenna systems for performance prediction characterized by scan loss and half-power beamwidth. The validation with the existing transmitarrays in the Ka and V bands is carried out. Using the proposed antenna model, the advantage of multibeam antenna to alleviate the impact of human blockage in millimeter-wave bands is highlighted. Communication performance is evaluated in terms of block error rate through the implementation of the 5G physical communication chain in a simulation tool.
10:10 - 10:20Uncertainty of Millimeter-Wave Channel Sounder due to Integration of Frequency Converters
Mar Francis De Guzman, Muhammad Hassan, Katsuyuki Haneda.
        In this study, we investigate the possible sources of measurement uncertainties with the integration of radio over fiber solution and frequency converters in millimeter-wave sounders. We examined analytically the effect of phase variations due to the disturbance of the optical fiber cable, the limited sideband suppression of the frequency converters, and the influence of the dispersion in rectangular waveguides to the response of the channel sounder. Characterization of the optical fiber cable confirms that disturbance of the cable leads only to phase variation. Back-to-back measurements of Aalto's sounder operating at V- and D-bands also verify that disturbance of the cable supplying the local (LO) continuous-wave signals are most influential to the stability of frequency- and delay-domain responses of the sounder because the LO signals undergo frequency multiplication. We found that the V-band and D-band channel sounders, with at least 17 dB and 20 dB Image Rejection Ratio, have the maximum gain variation of 0.5 dB and 1.0 dB in the peak of channel impulse responses when subject to different fiber cable positions.
10:20 - 10:30Impact of Directional Array Response on K-factor in Millimetre Wave Transmission
Shammi Farhana Islam, Alister Burr, David Grace.
        Future wireless communication in 5G and beyond will use millimetre waves (mmWave) because of the available bandwidth: however this requires directional antenna gain to overcome the pathloss in these bands. This paper explores the significant issue of multipath propagation characteristics for mmWave communication. We propose the novel distinction between the effective and the environmental K-factor for Ricean channels, and we further derive an approximation in closed form for the effective K-factor for the one ring scattering channel model, and corroborate it by comparison with simulation results.
10:30 - 10:40Real-time Physical Layer Secure Key Generation in a mmWave Communication System
Navaneetha C. Manjappa, Lara Wimmer, Nebojsa Maletic, Eckhard Grass.
        Physical layer security is one of the trending research areas in tackling data security issues of wireless networks. The main focus of this work is to explore practically the possibilities and performance of secret key generation solutions exploiting wireless channel randomness. This paper describes the implementation of a real-time secure key generation algorithm in a 60 GHz millimetre wave (mmWave) communication system. The performance of the algorithm is evaluated systematically for different parameter combinations to find the optimal parameter values for the system in an indoor static office environment.
11:00 - 12:00
Regular Session 4 : Coding and Modulation for Wireless Ssystems
Chair: Navaneetha C. Manjappa (Humboldt University of Berlin, ).
11:00 - 11:10Construction of Polar Codes Based on Piecewise Gaussian Approximation
Robert Oliveira, Rodrigo de Lamare.
        In this paper, we investigate the construction of polar codes by Gaussian approximation (GA) and develop an approach based on piecewise Gaussian approximation (PGA). In particular, with the piecewise approach we obtain a function that replaces the original GA function with a more accurate approximation, which results in significant gain in performance. The proposed PGA construction of polar codes is presented in its integral form as well as an alternative approximation that does not rely on the integral form. Simulations results show that the proposed PGA construction outperforms the standard GA for several examples of polar codes and rates.
11:10 - 11:20Decoding and Convergence Analysis for Distributed Low Density Lattice Codes
Xuebo Wang, Wai Ho Mow.
        Distributed low density lattice codes (D-LDLCs) have been proposed for application in cooperative communication networks. D-LDLCs are able to achieve a higher coding gain than LDLCs under the same code length and transmission power. However, an efficient decoder for D-LDLCs is still lacking. The state-of-the-art message passing decoder for LDLCs can be extended to decode D-LDLCs, but its complexity analysis requires an asymptotic characterization of the decoding behavior in terms of the convergence of the message variances. In this paper, we prove that as the number of iterations tends to infinity, the message variances converge to some constants determined by the code parameters of D-LDLCs. Based on the convergence analysis of message variances, we can further show that the extended decoder achieves linear complexity with respect to the column degree of the D-LDLC check matrix.
11:20 - 11:30Density Evolution Based Multi-Level Polar Coded Modulation
Guodong Sun, Yao Zhu, Yulin Hu, Jian Zhang, Anke Schmeink.
        Motivated by the capacity-approaching property of both binary polar codes (PCs) and the multi-level coding (MLC) scheme, we consider the design of modulated PC over additive white Gaussian noise (AWGN) channels. The capability of modulated PC essentially depends on the selection of information bits set from all the virtual bit channels formed by both modulation and channel polarization. To this end, we characterize the a-priori distribution density as the sufficient statistic for the bit channel of individual modulation levels formed by an MLC scheme, in which the codeword of symbols is split into parallel bits streams. According to the factor graph generated by the binary PC, we apply the density evolution (DE) for each binary modulation level. Consequently, distribution densities of every bit within the modulated codeword can be obtained and we select the most reliable bits as information bits and set the complement as frozen bits. Comprehensive simulations demonstrate the validness of this approach compared to the benchmark scheme.
11:30 - 11:40Time-frequency tiling and the BER performance of QAM-FBMC systems with short filters
Iandra Galdino, Didier Le Ruyet, Rostom Zakaria, Marcello Campos.
        The intrinsic interference observed at the receiver in QAM-FBMC (Quadrature Amplitude Modulation Filterbank Multicarrier) systems can be a source of problems when combined with MIMO techniques (multiple-input multiple-output). In an attempt to overcome the intrinsic interference of the QAM-FBMC system, in this paper, we propose to change the time spacing and frequency spacing of the traditional system. In this sense, we evaluate the applicability of a quincunx lattice structure to the QAM-FBMC systems that use short filters, which means an overlapping factor of one. We evaluate the traditional system performance, with rectangular lattice, through the simulations of bit error rate (BER) when using short filters found in the literature and compare to the performance when using the quincunx lattice.
12:00 - 13:00
Special Session 5 : Joint Communications and Sensing Systems
Chair: Marina Petrova (KTH Royal Institute of Technolgy, ).
12:00 - 12:10Converging Radar and Communications in the Superposition Transmission
Wenbo Wang, Bo Tan, Elena Simona Lohan, Mikko Valkama.
        This paper proposes a superposition transmission scheme for the future Radio Frequency (RF) convergence applications. The scheme is discussed under the assumption of a mono-static broadcasting channel topology. Under communications quality-of-service (QoS) constraints, the joint performance region of communications sum rate and radar estimation error variance is studied. Two radar signal waveforms, namely linear FM and parabolic FM, are used to investigate how signal shapes may influence the estimation accuracy. Both waveforms are generated with rectangular envelope. In the end, a numerical analysis is applied, which concludes that a moderate communications QoS promises a good communications fairness while with the limited radar performance degradation.
12:10 - 12:20Hybrid Beamforming for Terahertz Joint Ultra-Massive MIMO Radar-Communications
Ahmet Elbir, Kumar Vijay Mishra, Symeon Chatzinotas.
        In this paper, we investigate the hybrid beamforming problem in joint radar-communications at terahertz (THz) bands. In order to address the extremely high attenuation at THz, ultra-massive multiple-input multiple-output (UM-MIMO) antenna systems have been proposed for THz communications to compensate propagation losses. Further, we propose a new group-of-subarrays (GoSA) UM-MIMO structure to reduce the hardware cost. We formulate the GoSA beamformer design as an optimization problem to provide a trade-off between the unconstrained communications beamformers and the desired radar beamformers. Numerical experiments demonstrate that the proposed approach outperforms the conventional approaches in terms of spectral efficiency and hardware costs.
12:20 - 12:30Spectrum Efficient Distributed LFMCW Radar System for High Resolution Localization
Yen-Chin Wang, Danijela Cabric.
        Linear frequency modulated continuous wave (LFMCW) radars have been widely used for short/medium range target detection and estimation. However, the resolution of range estimation is strictly limited by the bandwidth of the LFMCW signal. In this paper, we propose a compressed-sensing based (CS-based) localization algorithm for high resolution localization based on a distributed LFMCW radar system. Instead of estimating the range of the object first and then feeding it to the localization kernel, we jointly process LFMCW beat signals and map them into a preconstructed dictionary. The proposed one-step procedure avoids the range estimation bias caused by the FFT from a single radar that can dominate the localization error of the entire distributed radar system. We developed simulation models and conducted experiments to verify our localization algorithm. Simulation results show that the proposed localization algorithm greatly improves the localization resolution with reduced bandwidth requirement of LFMCW signal compared to a conventional algorithm based on FFT and trilateration. For the experiments, we tested our CS-based localization using commercial off-the-shelf sensor (COTS) mmWave radar board from Texas Instrument. The experimental results showed that with 3 distributed radars, the proposed CS-based localization can be two times more accurate than the FFT and trilateration combination.
13:00 - 14:00
Special Session 6 : Machine Learning for Wireless Communications
Chair: Dirk Wübben (University of Bremen, ).
13:00 - 13:10Two-Sample Tests for Validating the UL-DL Conjecture in FDD Systems
Valentina Rizzello, Nurettin Turan, Michael Joham, Wolfgang Utschick.
        In this work, we present a two-sample tests analysis based on the maximum mean discrepancy metric to validate the recently proposed uplink-downlink conjecture for frequency division duplex systems. This novel concept shows that a neural network trained with uplink channel data can adequately generalize to downlink channel data. With this paper, we focus on a particular application of this idea, namely an autoencoder neural network, which has been introduced lately to generate channel feedback, without requiring any training effort at the mobile terminals. Simulation results with several datasets demonstrate that application-based low-dimensional representations for two-sample testing give a deeper insight into the similarities and dissimilarities between the uplink and downlink data distributions and are in accordance with the performance of the neural network that is applied to the respective datasets.
13:10 - 13:20Learning to Perform Downlink Channel Estimation in Massive MIMO Systems
Amin Ghazanfari, Trinh Chien, Emil Björnson, Erik G. Larsson.
        We study downlink (DL) channel estimation in a multi-cell Massive multiple-input multiple-output (MIMO) system operating in a time-division duplex. The users must know their effective channel gains to decode their received DL data signals. A common approach is to use the mean value as the estimate, motivated by channel hardening, but this is associated with a substantial performance loss in non-isotropic scattering environments. We propose two novel estimation methods. The first method is model-aided and utilizes asymptotic arguments to identify a connection between the effective channel gain and the average received power during a coherence block. The second one is a deep-learning-based approach that uses a neural network to identify a mapping between the available information and the effective channel gain. We compare the proposed methods against other benchmarks in terms of normalized mean-squared error and spectral efficiency (SE). The proposed methods provide substantial improvements, with the learning-based solution being the best of the considered estimators.
13:20 - 13:30Improving Channel Charting using a Split Triplet Loss and an Inertial Regularizer
Brian Rappaport, Emre Gönültaş, Jakob Hoydis, Maximilian Arnold, Pavan Koteshwar Srinath, Christoph Studer.
        Channel charting is an emerging technology that enables self-supervised pseudo-localization of user equipments by performing dimensionality reduction on large channel-state information (CSI) databases that are passively collected at infrastructure base stations or access points. In this paper, we introduce a new dimensionality reduction method specifically designed for channel charting using a novel split triplet loss, which utilizes physical information available during the CSI acquisition process. In addition, we propose a novel regularizer that exploits the physical concept of inertia, which significantly improves the quality of the learned channel charts. We provide an experimental verification of our methods using synthetic and real-world measured CSI datasets, and we demonstrate that our methods are able to outperform the state-of-the-art in channel charting based on the triplet loss.
13:30 - 13:40Neural Network-based Forecasting of Decodability for Early ARQ
Matthias Hummert, Dirk Wübben, Armin Dekorsy.
        Forecasting the decodability of a received packet of a given decoder is a hard task as many State-of-the-Art (SoTA) decoders are of high complexity and not easy to analyse in an analytical fashion. Gathering this forecast on the other hand would enable to save computational complexity and latency as a decoder execution can be saved if it is unlikely that the received packet is decoded correctly. On top, we can provide early feedback for Automatic Repeat Request (ARQ) schemes before actually running the decoding chain. Guided by this motivation, several approaches of classifying the received packet before the actual decoding process have been discussed. We propose to use neural networks (NN) in the context of forecasting received packets for a given receiver chain. We evaluate the performance of the NN by evaluating different performance metrics and perform an efficiency analysis of ARQ.
13:40 - 13:50Bit-wise Autoencoder for Multiple Antenna Systems
Sebastian Dörner, Sarah Rottacker, Marc Gauger, Stephan ten Brink.
        We propose an end-to-end learned bit-wise autoencoder neural network (NN) for open loop multiple-input multiple-output (MIMO) antenna based communication systems. The optimized transmit vector constellations are learned based on the number of transmit and receive antennas, the number of bits conveyed per channel use and the signal-to-noise ratio. By training through an i.i.d. complex Gaussian (i.e., Rayleigh ergodic) matrix channel, the system implicitly picks up constellation shaping gains "along the way". We evaluate and analyze these gains in comparison to the single-input single-output (SISO) results shown in [1] for different symmetric and asymmetric MIMO configurations. We first show that the NN-based receiver is able to compete with the a posteriori probability (APP) receiver performance up to certain configuration settings. Then we perform an end-to-end optimization of the transmit vector constellations using the conventional APP receiver as the decoder part. Thereby, we also investigate an edge case where the number of bits per vector symbol is not a multiple of the number of transmit antennas. Finally, we examine the performance of the system if a non-optimal zero forcing (ZF) receiver is used for inference, while the vector constellation was optimized for the APP receiver during training. We show that constellations optimized for the APP receiver are not necessarily optimal for such sub-optimal receivers that operate with reduced complexity. To fix this, we propose a detector-aware training scheme to learn constellations that have been optimized for a specific sub-optimal receiver and, thus, achieve higher performance in inference.
14:00 - 15:00
Special Session 4 : Fiber Optical Communications
Chair: Alex Alvarado (Eindhoven University of Technology (TU/e), ); Gabriele Liga (Eindhoven University of Technology, ).
14:00 - 14:10Shortening Solitons for Fiber-Optic Transmission
Sander Wahls.
        Solitons are stable localized pulses that do not disperse in optical fiber. When several solitons interact, they form a multi-soliton. Various fiber-optic communication systems based on multi-solitons have been investigated, but their spectral efficiencies are not competitive. One issue with using multi-solitons for communications is that their effective duration can vary widely with the number of interacting solitons. In this paper, we therefore introduce the concept of soliton shortening. In soliton shortening, a dispersive part is added to the nonlinear spectrum of a multi-soliton that reduces the pulse to a fixed finite duration, without changing the characteristics of the solitonic part. As a proof of concept, soliton shortening is shown to increase the spectral efficiency of a 2-soliton on-off keying system by 40%.
14:10 - 14:20Multichannel Digital Backpropagation with XPM-Aware ESSFM
Stella Civelli, Enrico Forestieri, Alexey Lotsmanov, Dmitry Razdoburdin, Marco Secondini.
        A novel technique for multi-channel digital backpropagation (DBP) in wavelength-division multiplexing systems is proposed. The nonlinear step of the conventional split step Fourier method (SSFM) is extended to account for the interplay of dispersion and inter- and intra- channel nonlinearities. The technique is referred to as coupled-channel enhanced SSFM and, by simulation, it is shown to provide better performance than existing equivalent complexity single-channel DBP techniques.
14:20 - 14:30Regular Perturbation and Achievable Rates of Space-Division Multiplexed Optical Channels
Francisco Javier Garcia Gomez, Gerhard Kramer.
        Regular perturbation is applied to space-division multiplexing (SDM) on optical fibers and motivates a correlated rotation-and-additive noise (CRAN) model. For S spatial modes, or 2S complex-alphabet channels, the model has 4S(S+1) hidden independent real Gauss-Markov processes, of which 2S model phase noise, 2S(2S-1) model spatial mode rotation, and 4S model additive noise. Achievable information rates of multi-carrier communication are computed by using particle filters. For S=2 spatial modes with strong coupling and a 1000 km link, joint processing of the spatial modes gains 0.5 bits/s/Hz/channel in rate and 1.4 dB in power with respect to separate processing of 2S complex-alphabet channels without considering CRAN.
14:30 - 14:40Nonlinear Digital Compensation for Spatial Multiplexing Systems
Filipe Ferreira.
        We review the latest advances on digital backward-propagation for the compensation of inter-channel nonlinear interference in spatial- and wavelength-multiplexed systems. Different solution methods of the multimode Schrödinger equation are compared for challenging linear mode coupling and differential mode delay conditions, highlighting the significant relaxation of the step size requirements provided by the separate-channels approach.
14:40 - 14:50Extending Fibre Nonlinear Interference Models to the Full Dual-Polarisation 4D Space of Transmitted Modulation Formats (Invited Talk)
Gabriele Liga.
        In spite of their popularity in the optical communication field, analytical models for fibre nonlinear propagation effects are only applicable to a small subset of the dual-polarisation modulation formats 4D space: the so-called polarisation-multiplexed 2D formats. In this talk, we will review our recently introduced analytical model for fibre nonlinear interference induced by general dual-polarisation 4D modulation formats. Its application to 4D constellation shaping for the optical fibre channel will also be discussed.
15:00 - 16:00
Special Session 8 : Physical Layer Security
Chair: Onur Günlü (University of Siegen, ); Rafael Schaefer (University of Siegen, ).
15:00 - 15:10To Jam or Not to Jam in Gaussian MIMO Wiretap Channels?
Mahdi Khojastehnia, Sergey Loyka.
        The popular technique of secure signaling over Gaussian MIMO wiretap channels, which makes use of artificial noise (AN) to increase secrecy rates, is considered. First, we briefly review the current state of affairs in this area and then provide new analytical results and insights on the usefulness of AN (jamming) to boost secrecy rates. The settings considered here go beyond the total transmit power constraint and include a number of additional constraints, such as interference (cognitive radio) and energy-harvesting constraints, for which the feasible set is not isotropic anymore so that the standard tools of the analysis cannot be used. By closely examining optimal precoding for the information-bearing and AN signals, we identify a number of cases where it is optimal to transmit no artificial noise at all (so that all the transmit power goes to the information-bearing signal). These cases include a fixed (no fading) MIMO WTC with single eavesdropper (for which we give a direct matrix-theoretic proof using novel matrix inequalities), multi-eavesdropper (compound) degraded and reversely-degraded channels, and multi-eavesdropper channels where there exists a dominant eavesdropper (for which we give a precise definition) or when the eavesdroppers collude. To improve secrecy rates by using AN, one has to look elsewhere.
15:10 - 15:20Secure Communication in a Multi-antenna Wiretap Channel with a Reconfigurable Intelligent Surface
Mohamed Nafea, Aylin Yener.
        Reconfigurable Intelligent Surfaces (RIS) are being considered as a candidate technology for next generation of wireless systems (6G), for improving reliability and range extension owing to their low cost and complexity, and suitability for high-frequency schemes. RIS terminals can effectively operate as relaying nodes for transmitted signals, while saving the energy needed for Radio Frequency (RF) transmission. This is implemented by deploying controllable reflecting arrays of meta-surface elements, whose phase can be adjusted by applying fast switching voltage. RIS thus creates a valuable resource in wireless communication: the control over the channel realizations from the RIS relays to the receiver. In this work, we investigate the impact of this resource on improving secure communication rates between a transmitter (base station) and a receiver (end user), in the presence of an external eavesdropper. We consider a multi-antenna wiretap channel aided with a RIS array, and derive the achievable secure degrees of freedom for various number of antennas at different terminals. Our achievability scheme relies on designing the RIS beamforming such that the signals received at the eavesdropper experience destructive interference. Compared to our previous work on multi-antenna wiretap channel with a multi-antenna helper, where active user cooperation enables/improves secure communication rates, here secure communication is enabled/improved by utilizing passive terminals (deployed at low cost).
15:20 - 15:30Achievable Physical-Layer Secrecy in Multi-Mode Fiber Channels using Artificial Noise
Eduard Jorswieck, Andrew Lonnstrom, Karl-Ludwig Besser, Stefan Rothe, Jürgen Czarske.
        Reliable and secure communication is an important aspect of modern fiber optic communication. In this work we consider a multi-mode fiber (MMF) channel wiretapped by an eavesdropper. We assume the transmitter knows the legitimate channel, but statistical knowledge of the eavesdropper's channel only. We propose a transmission scheme with artificial noise (AN) for such a channel. In particular, we formulate the corresponding optimization problem which aims to maximize the average secrecy rate and develop an algorithm to solve it. We apply this algorithm to actual measured MMF channels. As real fiber measurements show, for a 55 mode MMF we can achieve positive average secrecy rates with the proper use of AN. Furthermore, the gain compared to standard precoding and power allocation schemes is illustrated.
15:30 - 15:40Privacy-Aware Localization Enhancement Based on Intelligent Reconfigurable Surfaces
Stefan Roth, Roman Bessel, Aydin Sezgin.
        5G networks enhance the localization performance for both legitimate, yet also for the misuse by adversarial devices. To distinguish between legitimate and adversarial devices, an intelligent reconfigurable surface (IRS) can be configured to only optimize the channel for localization when a user equipment (UE) is localizing itself. The channel comprises a direct part between the new-generation node base (gNB) and the UE, and an indirect part over the IRS. We aim at maximizing the mutual information between the channel and the received signal by adjusting the transmit signal of the gNB and the IRS configuration alternately. In order to allow the UEs to localize themselves on behalf of its own received signal, a publicly known data-set of fingerprints is transmitted to the UEs. For the actual localization, the optimized IRS configuration is enabled for a short time instant and the optimized transmit signal broadcasted. Both parameters are optimized for the channel statistics of a subset of the cell area, in which the UE is situated, rather than an actual channel. Hence, adversaries can only obtain a coarse localization based on the channel statistics. The proposed technique enables an enhanced localization performance compared with the IRS-free case.
15:40 - 15:50Semantic Security for Indoor THz-Wireless Communication
Rebekka Schulz, Onur Günlü, Robert Elschner, Rafael Schaefer, Carsten Schmidt-Langhorst, Colja Schubert, Robert Fischer.
        Physical-layer security (PLS) for industrial indoor terahertz (THz) wireless communication applications is considered. We use a similar model as being employed for additive white Gaussian noise (AWGN) wireless communication channels. A cell communication and a directed communication scenario are analyzed to illustrate the achievable semantic security guarantees for a wiretap channel with finite-blocklength THz-wireless communication links. We show that weakly directed transmitter (Alice) antennas, which allow cell-type communication with multiple legitimate receivers (Bobs) without adaptation of the alignment, result in large insecure regions. In the directed communication scenario, the resulting insecure regions are shown to cover a large volume of the indoor environment only if the distance between Alice and Bob is large. Thus, our results for the two selected scenarios reveal that there is a stringent trade-off between the targeted semantic security level and the number of reliably and securely accessible legitimate receivers. Furthermore, the effects of secrecy code parameters and antenna properties on the achievable semantic security levels are illustrated to show directions for possible improvements to guarantee practically-acceptable security levels with PLS methods for industrial indoor THz-wireless communication applications.
16:00 - 17:00
Special Session 9 : Research Challenges for 6G
Chair: Alessio Zappone (University of Cassino and Southern Lazio, ).
16:00 - 16:10Rate-Splitting Multiple Access for Enhanced URLLC and eMBB in 6G
Onur Dizdar, Yijie Mao, Yunnuo Xu, Peiying Zhu, Bruno Clerckx.
        Rate-Splitting Multiple Access (RSMA) is a flexible and robust multiple access scheme for downlink multi-antenna wireless networks. RSMA relies on Rate-Splitting (RS) at the transmitter and Successive Interference Cancellation (SIC) at the receivers. In this work, we study the performance of RSMA in the scenarios related with the important core services of New Radio (NR) and 6G, namely, enhanced Ultra-Reliable and Low-Latency (URLLC) and enhanced Mobile Broadband Communications (eMBB). We present the optimal system designs employing RSMA that target short-packet and low-latency communications as well as robust communications with high-throughput under the practical and important setup of imperfect Channel State Information at Transmitter (CSIT) originating from user mobility and latency/delay (between CSI acquisition and data transmission) in the network. We demonstrate via numerical results that RSMA achieves significantly higher performance than Space Division Multiple Access (SDMA) and Non-Orthogonal Multiple Access (NOMA), and is capable of addressing the requirements for enhanced URLLC and eMBB in 6G efficiently.
16:10 - 16:20Entanglement Rate Optimization in Heterogeneous Quantum Communication Networks
Mahdi Chehimi, Walid Saad.
        Quantum communication networks are emerging as a promising technology that could constitute a key building block in future communication networks in the 6G era and beyond. These networks have an inherent feature of parallelism that allows them to boost the capacity and enhance the security of communication systems. Recent advances led to the deployment of small- and large-scale quantum communication networks with real quantum hardware. In quantum networks, entanglement is a key resource that allows for data transmission between different nodes. However, to reap the benefits of entanglement and enable efficient quantum communication, the number of generated entangled pairs must be optimized. Indeed, if the entanglement generation rates are not optimized, then some of these valuable resources will be discarded and lost. In this paper, the problem of optimizing the entanglement generation rates and their distribution over a quantum memory is studied. In particular, a quantum network in which users have heterogeneous distances and applications is considered. This problem is posed as a mixed integer nonlinear programming optimization problem whose goal is to efficiently utilize the available quantum memory by distributing the quantum entangled pairs in a way that maximizes the user satisfaction. An interior point optimization method is used to solve the optimization problem and extensive simulations are conducted to evaluate the effectiveness of the proposed system. Simulation results show the key design considerations for efficient quantum networks, and the effect of different network parameters on the network performance.
16:20 - 16:30AoI Aware Radio Resource Management of Autonomous Platoons via Multi Agent Reinforcement Learning
Mohammad Parvini, Mohammad Reza Javan, Nader Mokari, Bijan Arand, Eduard Jorswieck.
        This paper investigates the problem of age of information (AoI) aware radio resource management for a platooning system. Multiple autonomous platoons exploit the cellular wireless vehicle-to-everything (C-V2X) communication technology to disseminate the cooperative awareness messages (CAMs) to their followers while ensuring timely delivery of safety-critical messages to the Road-Side Unit (RSU). Due to the challenges of dynamic channel conditions, centralized resource management schemes that require global information are inefficient and lead to large signaling overheads. Hence, we exploit a distributed resource allocation framework based on multi-agent reinforcement learning (MARL), where each platoon leader (PL) acts as an agent and interacts with the environment to learn its optimal policy. Existing RL algorithms consider a holistic reward function for the group's collective success, which often ends up with unsatisfactory results and cannot obtain an optimal policy for each agent. Consequently, we modify the MARL framework in a way that each agent learns to find an optimal policy to improve its individual reward according to its actions and observations while cooperating with other agents to learn a global team reward. Numerical results indicate our proposed algorithm's effectiveness compared with the conventional RL methods applied in this area.
16:30 - 16:40Affine Frequency Division Multiplexing for Next-Generation Wireless Networks
Ali Bemani, Giampaolo Cuozzo, Nassar Ksairi, Marios Kountouris.
        Affine Frequency Division Multiplexing (AFDM) is a new multi-chirp waveform that can be generated and demodulated using the discrete affine Fourier transform (DAFT). DAFT is a generalization of discrete Fourier transform characterized with two parameters which can be adapted to better cope with both doubly dispersive channels and impairments at high-frequency bands. DAFT domain impulse response can indeed convey a full delay-Doppler representation of linear time-varying (LTV) channels, which allows AFDM to achieve the full diversity. Moreover, AFDM signals are maximally spread in time and frequency, thus providing a coverage gain that turns out to be robust against radio frequency impairments, such as carrier frequency offset and phase noise. In this paper, we show that AFDM offers the aforementioned advantages while being compatible with practical pilot-aided channel estimation and low-complexity channel equalization. Our analytical and simulation results evince that AFDM achieves significant throughput and reliability gains over state-of-the-art multicarrier modulation.
17:00 - 20:00
Tutorial 4 : Rate-Splitting Multiple Access for 6G
Bruno Clerckx, Yijie Mao, Onur Dizdar
This tutorial argues that to efficiently cope with the high throughput, reliability, heterogeneity of Quality-of-Service (QoS), and massive connectivity requirements of future multi-antenna wireless networks, multiple access and multiuser communication system design need to depart from the two extreme interference management strategies, namely fully treat interference as noise (as commonly used in 5G, MU-MIMO, CoMP, Massive MIMO, millimetre wave MIMO) and fully decode interference (as in NOMA). In this tutorial, we depart from those two extremes and introduce the audience to a general and powerful multiple access framework called Rate-Splitting Multiple Access (RSMA) for MIMO networks. RSMA relies on multi-antenna Rate-Splitting (RS) at the transmitter and successive interference cancellation (SIC) at the receivers. RSMA relies on the split of messages and the non-orthogonal transmission of common messages decoded by multiple users, and private messages decoded by their corresponding users. This enables RSMA to partially decode interference and partially treat the remaining interference as noise, and therefore softly bridge and reconcile the two extreme strategies of fully decode interference and treat interference as noise. As a result, RSMA provides a unified and flexible framework for the design and optimization of non-orthogonal transmission, multiple access, and interference management strategies. This tutorial is dedicated to the theory, design, optimization and applications of RSMA and demonstrates the significant benefits in terms of spectral/energy efficiencies, reliability and robustness to Channel State Information imperfections over conventional strategies used in 5G (multi-user MIMO, massive MIMO, CoMP, mmwave MIMO) and NOMA, in a wide range of deployments, network loads (underloaded, overloaded), services (unicast, multicast) and systems (terrestrial and satellite). The tutorial will give the audience a comprehensive introduction of the state-ofthe-art development in rate splitting theory and applications in the wireless communication and signal processing society.

Bruno Clerckx is a (Full) Professor, the Head of the Wireless Communications and Signal Processing Lab, and the Deputy Head of the Communications and Signal Processing Group, within the Electrical and Electronic Engineering Department, Imperial College London, London, U.K. He received the M.S. and Ph.D. degrees in Electrical Engineering from the Université Catholique de Louvain, Louvain-la-Neuve, Belgium, in 2000 and 2005, respectively. From 2006 to 2011, he was with Samsung Electronics, Suwon, South Korea, where he actively contributed to 4G (3GPP LTE/LTE-A and IEEE 802.16m) and acted as the Rapporteur for the 3GPP Coordinated Multi-Point (CoMP) Study Item. Since 2011, he has been with Imperial College London, first as a Lecturer from 2011 to 2015, Senior Lecturer from 2015 to 2017, Reader from 2017 to 2020, and now as a Full Professor. From 2014 to 2016, he also was an Associate Professor with Korea University, Seoul, South Korea. He also held various long or short-term visiting research appointments at Stanford University, EURECOM, National University of Singapore, The University of Hong Kong, Princeton University, The University of Edinburgh, The University of New South Wales, and Tsinghua University. He has authored two books on "MIMO Wireless Communications" and "MIMO Wireless Networks", 200 peer-reviewed international research papers, and 150 standards contributions, and is the inventor of 80 issued or pending patents among which 15 have been adopted in the specifications of 4G standards and are used by billions of devices worldwide. His research area is communication theory and signal processing for wireless networks. He has been a TPC member, a symposium chair, or a TPC chair of many symposia on communication theory, signal processing for communication and wireless communication for several leading international IEEE conferences. He was an Elected Member of the IEEE Signal Processing Society SPCOM Technical Committee. He served as an Editor for the IEEE TRANSACTIONS ON COMMUNICATIONS, the IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, and the IEEE TRANSACTIONS ON SIGNAL PROCESSING. He has also been a (lead) guest editor for special issues of the EURASIP Journal on Wireless Communications and Networking, IEEE ACCESS, the IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, the IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, and the PROCEEDINGS OF THE IEEE. He was an Editor for the 3GPP LTE-Advanced Standard Technical Report on CoMP. He is an IEEE Communications Society Distinguished Lecturer 2021-2022.

Yijie Mao received the B.Eng. degree from Beijing University of Posts and Telecommunications, and the B.Eng. (Hons.) degree from Queen Mary University of London (London, United Kingdom) in 2014. She received the Ph.D. degree in the Electrical and Electronic Engineering Department from the University of Hong Kong (Hong Kong, China) in 2018. She was a Postdoctoral Research Fellow at the University of Hong Kong from 2018 to 2019. Her research interests include Multiple Input Multiple Output (MIMO) communication networks, rate-splitting and non-orthogonal multiple access for 5G and beyond.

Onur Dizdar received the B.Sc. and M.Sc. degrees in Electrical and Electronics Engineering from Middle East Technical University, Ankara, Turkey, in 2008 and 2011. He received his Ph.D. in Electrical and Electronics Engineering from Bilkent University, Ankara, Turkey, in 2017. He also worked as a communications system design engineer in ASELSAN, Turkey from 2008 to 2019. He is currently a postdoctoral research associate in the Communications and Signal Processing Group at Imperial College London. His research interests include wireless communications, error-correcting codes and decoding algorithms, rate-splitting and non-orthogonal multiple access and signal processing.

Day 4 : 09 Sept. 2021

10:00 - 11:00
Special Session 10 : Selected Topics in 6G Security
Chair: Arsenia Chorti (ETIS UMR 8051, CY University, ENSEA, CNRS, ).
10:00 - 10:15Context-Aware Security for 6G Wireless: The Role of Physical Layer Security (Invited Talk)
H. Vincent Poor.
        Sixth generation systems are expected to face new security challenges, while opening up new frontiers towards context awareness at the wireless edge. The workhorse behind this projected technological leap will be a whole new set of sensing capabilities predicted for 6G devices, in addition to the ability to achieve high precision localization. The combination of these enhanced traits can give rise to a new breed of context aware security protocols, following the quality of security (QoSec) paradigm. In this framework, physical layer security solutions emerge as competitive candidates for low complexity, low-delay and low-footprint, adaptive, flexible and context aware security schemes, leveraging the physical layer of the communications in genuinely cross-layer protocols, for the first time. (Joint work with Arsenia Chorti, Andr´e Noll Barreto, Stefan K¨opsell, Marco Zoli, Marwa Chafii, Philippe Sehier and Gerhard Fettweiss).
10:15 - 10:25A Distributed Ledger with Trust-Based Data Aggregation for a Lightweight IoT Network
Tanmayee Deshprabhu, Justin Coon, Mihai-Alin Badiu.
        This paper addresses the need for a secure data management framework for lightweight Internet of Things (IoT) networks. Existing approaches rely on capable nodes or external cloud technology to carry out key functions for the lightweight IoT nodes, such as data processing, storage or routing. Instead, this paper considers a fully lightweight network or an existing network where the more capable nodes have failed. We propose a novel data management framework using a lightweight distributed ledger for IoT networks. This includes a trust-based data aggregation protocol in which data from untrustworthy nodes is not disregarded, but is instead utilised to strengthen the aggregation result. MATLAB simulations show that the proposed aggregation scheme infers data with high accuracy for both trustworthy and untrustworthy networks. Neutral networks exhibit a higher error rate but the maximum error rate decreases for larger networks.
10:25 - 10:35Deep Neural Networks for Multicarrier Waveforms Classification in UAV Networks
Kawtar Zerhouni, El Mehdi Amhoud, Guevara Noubir.
        During the last decade, the adoption of Unmanned aerial vehicles (UAV) for wireless networks has been rapidly growing for both civilian and military applications, due to their flexibility and mobility. In this paper, we consider their use as an aerial base station, then investigate the task of automatic signal recognition (ASR) through a deep learning (DL) approach, while considering spectrally efficient filtered multicarrier waveforms, including UFMC, F-OFDM, FBMC and GFDM compared to the legacy OFDM. This study has been done through series of simulations; in each one, different filter sizes, number of filters and number of convolutional layers have been applied. The best performance, with an overall accuracy of 0.93 at 2 dB signal to noise ratio (SNR), has been obtained when using smaller networks, with smaller filter sizes and higher number of filters.
10:35 - 10:45Estimation of the Secret Key Rate in Wideband Wireless Physical-Layer-Security
Marco Zoli, Miroslav Mitev, Andre Barreto, Gerhard Fettweis.
        In this work we investigate the problem of secret key generation (SKG) between two communicating wireless devices, according to the physical-layer security paradigm. We propose a general framework for any communication channel or waveform. In details, we study a filterbank-based method, which allows the generation of secret security keys from a wideband radio channel, independently from the baseband modem implementation. We believe that channel awareness is of utmost importance to understand the applicability of SKG methods, i.e., knowing their secret bit-rate under different channel scenarios. For that purpose, we investigate the SKG performance by means of Monte Carlo simulations that collect radio channel statistics and obtain the SKG performance through mutual information numerical estimation.
11:00 - 12:00
Special Session 11 : Tactile Internet & 5G
Chair: Frank Fitzek (Technische Universität Dresden, ).
11:00 - 11:10Learning-Adaptive Deadband Sampling for Teleoperation-based Skill Transfer over the Tactile Internet
Basak Gulecyuz, Luca Oppici, Xiao Xu, Andreas Noll, Eckehard Steinbach.
        In remote skill transfer, demonstrations of a task are provided over a network via teleoperation and the remote robot learns from these teleoperated demonstrations. In a typical bilateral teleoperation scenario, transmission of position/velocity and force/torque samples require high packet rates for system transparency. In this paper we present a data rate efficient approach in teleoperation while ensuring robust remote learning from demonstrations. Our approach adapts the deadband parameter in the perceptual deadband-based kinesthetic data reduction method considering the confidence in the learned model. Our experimental results show that the mean packet rate to achieve the same quality of learning is drastically reduced when using the proposed approach.
11:10 - 11:20Frontiers of Transdisciplinary Research in Tactile Internet with Human-in-the-Loop
Frank Fitzek, Shu-Chen Li, Stefanie Speidel, Thorsten Strufe, Patrick Seeling.
        Recent technological advances in developing intelligent telecommunication networks, ultra-compact bendable wireless transceiver chips, adaptive wearable sensors and actuators, and secure computing infrastructures along with the progress made in psychology and neuroscience for understanding neurocognitive and computational principles of human behavior combined have paved the way for a new field of research: Tactile Internet with Human-in-the-Loop (TaHiL). This emerging field of transdisciplinary research aims to promote next generation digitalized human-machine interactions in perceived real time. To achieve this goal, mechanisms and principles of human goal-directed multisensory perception and action need to be integrated into technological designs for breakthrough innovations in mobile telecommunication, electronics and materials engineering, as well as computing. This overview highlights key challenges and the frontiers of research in the new field of TaHiL. Revolutionizing the current Internet as a digital infrastructure for sharing visual and auditory information globally, the TaHiL research will enable humans to share tactile and haptic information and thus veridically immerse themselves into virtual, remote, or inaccessible real environments to exchange skills and expertise with other humans or machines for applications in medicine, industry, and the Internet of Skills.
12:00 - 13:00
Special Session 12 : URLLC & Industrial Networking
Chair: Krister Landernäs (ABB Corporate Research Västerås, ); Joachim Sachs (Ericsson Research, ).
12:00 - 12:10Review of 5G capabilities for smart manufacturing
Joachim Sachs, Krister Landernäs.
        5G has been defined to address new use cases beyond consumer-focused mobile broadband services. In particular industrial use cases, for example in smart manufacturing, have been addressed in the 5G standardization, so that 5G can support industrial IoT services and wireless industrial networking. To this end, 5G needs to integrate with the industrial network based on Ethernet and TSN. 5G can create new opportunities for smart manufacturing by enabling flexibility and increasing the automation in the production. This paper provides an overview of the use cases and requirements for smart manufacturing that can be addressed with 5G and which are validated in three industrial 5G trial systems. The capabilities of 5G are described for providing non-public networks that support industrial LAN services based on Ethernet and TSN. The 5G radio access network functionality is described and discussed for practical deployments. The paper provides an overview of the current state-of-the-art of using 5G for smart manufacturing.
12:10 - 12:20Joint Power and Blocklength Allocation for Energy-Efficient Ultra-Reliable and Low-Latency Communications
Richard Mugisha, Aamir Mahmood, Sarder Fakhrul Abedin, Luca Beltramelli, Mikael Gidlund.
        In this work, we address the problem of jointly optimizing the transmit power and blocklength of a two-users scenario for orthogonal multiple access (OMA) and non-orthogonal (NOMA) access schemes. We formulate an optimization problem to obtain the energy-optimal blocklength and transmit power under ultra-reliable and low-latency communications (URLLC) reliability and latency constraints. The aim is to minimize the energy consumption at short-blocklength regime. Due to the problem's complexity, we decompose it into two sub-problems for the OMA case, where the base station (BS) employs a 2D search for strong user, and the bisection method for the weak user. On the contrary, we find the sufficient transmit power conditions for NOMA to obtain the feasible solution. Our results show that the minimum required energy increases with the reliability requirement for both the OMA and NOMA, while NOMA consumes more energy than OMA for the same reliability target. Moreover, the results indicate that NOMA reduces latency due to better blocklength utilization compared to OMA when the channel gain disparity between the users is small.
12:20 - 12:30Enhancing 5G URLLC for Industrial IoT with Device-to-Device Communication
Piyush Gupta, Silas Fong, Xiaojie Wang, Sherif ElAzzouni, Rajat Prakash, Fatih Ulupinar, Xiaoxia Zhang.
        In this paper, we discuss utilizing device-to-device communication, i.e., sidelink, with 5G URLLC for meeting the stringent latency/reliability requirements in certain industrial IoT scenarios, e.g., factory automation. In particular, we describe various aspects for one specific use-case of wireless controller: different architectures for combining gNB-UE links and UE-UE sidelinks; enabling enhancements at the physical, medium-access, and upper-layers; some results of performance evaluation; and a prototype.
12:30 - 12:40Attention-based Reinforcement Learning for Real-Time UAV Semantic Communication
Won Joon Yun, Byungju Lim, Soyi Jung, Young-Chai Ko, Jihong Park, Joongheon Kim, Mehdi Bennis.
        In this article, we study the problem of air-to-ground ultra-reliable and low-latency communication (URLLC) for a moving ground user. This is done by controlling multiple unmanned aerial vehicles (UAVs) in real time while avoiding inter-UAV collisions. To this end, we propose a novel multi-agent deep reinforcement learning (MADRL) framework, coined a graph attention exchange network (GAXNet). In GAXNet, each UAV constructs an attention graph locally measuring the level of attention to its neighboring UAVs, while exchanging the attention weights with other UAVs so as to reduce the attention mismatch between them. Simulation results corroborates that GAXNet achieves up to 4.5x higher rewards during training. At execution, without incurring inter-UAV collisions, G2ANet improves reliability of air-to-ground network in terms of latency and error rate.
13:00 - 14:00
Regular Session 5 : PHY-Layer Modeling and Experimentation
Chair: Roberto Di Renna (Pontifical Catholic University of Rio de Janeiro, ).
13:00 - 13:10Faster-than-Nyquist Signaling Assigning Increased Resources to Parity Bits for Turbo-Coded OFDM
Tsubasa Shobudani, Mamoru Sawahashi, Kenichi Higuchi, Yoshihisa Kishiyama.
        This paper proposes faster-than-Nyquist (FTN) signaling that assigns an increased amount of resources to parity bits in order to decrease the required received signal-to-noise ratio (SNR) that satisfies the target block error rate (BLER) for turbo-coded orthogonal frequency division multiplexing (OFDM). By lowering the turbo coding rate while maintaining the same number of information bits in a channel-code block, the suppression levels of the inter-symbol-interference and inter-subcarrier-interference due to FTN signaling are increased for the minimum mean square error based turbo soft interference canceler. Computer simulation results show that the required received SNR at the BLER of 10^(-2) for FTN signaling is decreased by approximately 1.4 dB and 1.0 dB compared to that of cyclic prefix (CP) based OFDM for QPSK and 8PSK, respectively. We also show that the effect of the FTN signaling on the decrease in the required received SNR that satisfies the target BLER from the CP based OFDM is not obtained for 16QAM, although the effect is gained for 16PSK.
13:10 - 13:20USRP-Based Prototype for Real-Time Estimation of Channel Activity Statistics in Spectrum Sharing
Ogeen Toma, Miguel López-Benítez.
        The statistical characteristics of the frequency spectrum play a key role in decision making in smart spectrum sharing systems. In such systems, the activity of the licensed users changes differentially over both time and frequency, hence, their statistical information changes accordingly. The performance of spectrum sharing systems is directly affected by the estimated channel activity statistics, therefore low spectrum utilisation may result from inaccurate estimation of these statistical parameters. In this context, this work presents a prototype design for real-time estimation of channel activity statistics based on a Software Defined Radio (SDR) platform using USRP. A detailed explanation of both hardware and software implementations is provided (with free open source code). The developed platform will enable a spectrum sharing system adapt its parameters smartly and instantaneously in accordance with the estimated channel statistics in real-time. Moreover, this prototype will serve researchers and engineers to conduct and validate further research developments in statistics estimation methods and algorithms for spectrum sharing systems through experiments and proof-of-concept.
13:20 - 13:30Realistic power amplifier model for energy optimization in wireless networks
Marie-Anne Lacroix, Romuald Rocher, Pascal Scalart.
        This article addresses the problem of the optimal M-QAM order in a realistic energy model. Our researches focus on the power amplifier (PA) equation, which depends on transmission power, drain efficiency and peak-to-average ratio. These last two elements are never used together in the hardware parameters, especially those related to the digital analog converter. This study shows that drain efficiency and PAR can have a crucial importance in the estimation of the system energy consumption and the choice of the optimal modulation order. Furthermore, in traditional optimization studies, the maximal PA power is always neglected. However, in function of PA power allowed by the transceiver and the communication channel conditions, the modulation order might be revised to prevent quality of service loss.
13:30 - 13:40Investigation of Real-Valued Spreading Sequences for DSSS and PSSS
Lukasz Lopacinski, Nebojsa Maletic, Alireza Hasani, Jesús Gutiérrez, Eckhard Grass.
        This paper investigates signal-to-noise ratio (SNR) performance and hardware complexity of real-valued spreading sequences, which have all sequence coefficients defined in the real domain. These particular sequences can be employed for both direct-sequence spread spectrum (DSSS) and parallel sequence spread spectrum (PSSS). The simulation results reveal that real-valued sequences allow reducing the resulting peak-to-average power ratio (PAPR) in PSSS systems. Moreover, the cyclic-autocorrelation mainlobe amplitude maximization does not bring any advantages in DSSS and PSSS. Thus, more effort can be spent generating sequences with other specific characteristics than searching for the optimal sequence with respect to cyclic-autocorrelation mainlobe. Employing real-valued sequences gives a new dimension for optimization. The domain of possible R sequences is probably unlimited, and parameters like power consumption, chip area, PAPR can be directly optimized at the sequence coefficients level.
14:00 - 15:00
Regular Session 6 : Multiple Access and Resource Allocation
Chair: Bho Matthiesen (University of Bremen, ).
14:00 - 14:10Joint Activity Detection and Data Decoding for Grant-Free Massive MIMO Systems
Roberto Di Renna, Rodrigo de Lamare.
        This work addresses the problem of joint active device detection and data decoding in an uplink grant-free massive multiple-input multiple-output (MIMO) scenario. We develop a message-passing solution that uses channel decoder beliefs to refine the activity detection and data decoding. In order to improve the detection and decoding performance, we introduce a dynamic message-scheduling concept, where we apply scheduling techniques according to the activity user detection (AUD) and the residual belief propagation (RBP). Simulation results show that our proposed schemes outperform state-of-the-art algorithms in terms of frame error rate (FER), false alarms (FAR) and missed detection rates (MDR), requiring a small number of iterations for convergence and lower complexity.
14:10 - 14:20An Interference Minimization-Based RAN Slicing Strategy in 5G Systems
Huiling Li, Hang Li, Xiang Ming Wen, Luhan Wang, Zhaoming Lu, Wenpeng Jing, Yawen Chen.
        The evolving 5G virtualization technology is a key enabler for the radio access network (RAN) slicing, which aims to support services with differentiated requirements. One of the major challenges in RAN slicing is the inter-slice interference caused by the sharing of spectrum resources between different base stations (BSs). To tackle this obstacle and guarantee user experience, this paper first models a multi-base station network scenario. Then a resource allocation algorithm based on the non-interference of idle resources, Priority and Idle RBs Combined Algorithm (PICA), is proposed, whose main idea is to allocate the same time-frequency resource blocks (RBs) in different base stations to the same slice as much as possible to minimize the inter-slice interference. Finally, the simulation results show that our algorithm can not only keep relatively low time complexity but also increase the number of non-interference RBs by 5% to 19% compared with the typical priority-based algorithm.
14:20 - 14:30A Low-complexity Resource Optimization Technique for High Throughput Satellite
Tedros Abdu, Steven Kisseleff, Eva Lagunas, Symeon Chatzinotas.
        The high throughput satellites with flexible payloads are expected to provide a high data rate to satisfy the increasing traffic demand. Furthermore, the reconfiguration capability of flexible payloads opens the door to more advanced system optimization techniques and a better utilization of satellite resources. Consequently, we can obtain high demand satisfaction at the user side. For this, dynamically adaptive high-performance and low-complexity optimization algorithms are needed. In this paper, we propose a novel low-complexity resource optimization technique for geostationary (GEO) High Throughput Satellites. The proposed method minimizes the transmit power and the overall satellite bandwidth while satisfying the demand per beam. This optimization problem turns out to be non-convex. Hence, we convexify the problem using Dinkelbach method and Successive Convex Approximation (SCA). The simulation result shows that the proposed scheme provides better flexibility in resource allocation and requires less computational time compared to the state-of-art benchmark schemes.
14:30 - 14:40RRM Relaxation in Connected State for Reduced Capability (RedCap) NR UEs
Muhammad Tayyab, Hailu Sofonias, Rauli Jarvela, Niko Kolehmanen, Halit Murat Gürsu.
        3GPP Release 16 describes two UE criteria for radio resource management (RRM) relaxation, 'low mobility' and 'not at the cell edge'. This work presents a simulation analysis of RRM relaxation for reduced capability (RedCap) new radio (NR) UEs. Two categories are simulated, namely 'low mobility' and 'low mobility + not at the cell edge' to find the most suitable relaxation criteria for the RRC-Connected state. This work quantifies the energy savings that RRM relaxation brings for stationary and low mobility RedCap UEs with different relaxation intervals varied from 40 ms to 5120 ms. Furthermore, it identifies the cost of energy-saving in terms of radio link failures and handover failures. The simulation analysis shows that the 'low mobility + not at the cell edge' criteria is the most suitable for RedCap UEs in comparison to only 'low mobility' criteria. Also, high relaxation interval (i.e. 5120 ms) is suitable up to pedestrian UEs speeds.
15:00 - 16:00
Regular Session 7 : 5G Wireless Systems and Beyond
Chair: Emil Björnson (Linköping University, ).
15:00 - 15:10Iterative interference cancellation for the DFT Precoded Filter Bank System
Rogério Junior, Carlos Faria da Rocha, Bruno Chang, Didier Le Ruyet.
        Methods to remove the intrinsic interference in filter bank multicarrier system (FBMC) have been recently proposed in the literature. Precoding/decoding techniques like fast Fourier transform FBMC, block filtered OFDM and pruned DFT spread FBMC are some examples. In this paper, we propose an alternative technique called DFT Precoded Filter Bank associated to a novel iterative interference cancelation (IIC) receiver. The main idea is to use a prototype filter with a high overlapping factor to maintain good spectral confinement. On the other hand, this leads to an increase of the intrinsic interference in this alternative technique. The use of IIC together with this new transmission technique assures bit error rate (BER) performance as good as the one obtained when using prototype filters with a lower overlapping factor. Furthermore, simulations results also reveal robust performance in high mobility scenarios.
15:10 - 15:20Secure Hybrid RF/VLC under Statistical Queuing Constraints
Isabella da Silva, Diana Pamela Moya Osorio, Edgar Eduardo Benitez Olivo, Iqrar Ahmed, Marcos Katz.
        This paper evaluates the effective capacity and maximum average arrival rate of a hybrid radio frequency (RF) and visible light communication (VLC) network in the presence of an eavesdropper. It is assumed that the data is first stored in a buffer prior to transmission. Thus, it is considered that the source operates under constraints of buffer overflow probabilities. We also consider that the data is transmitted over the RF and VLC links following a proposed multiplex scheme in which the buffer service rate is described in terms of the secrecy capacity and split with a certain allocation ratio. Moreover, the legitimate and eavesdropper users are assumed to have multi-homing capabilities so that are able to receive data from both access points simultaneously. We formulate an integral-form and asymptotic expressions for the effective capacity and validate them via Monte Carlo simulations. From the numerical results, we show that combining RF and VLC and splitting the data among them can enhance the performance in terms of the buffer quality of service (QoS) constraints and secrecy requirements.
15:20 - 15:30Hierarchical Bayesian-based Indoor Positioning Using Distributed Antenna Systems
Leonardo Terças, Carlos Morais de Lima, Jani Saloranta, Matti Latva-aho.
        This work proposes and evaluates hierarchical Bayesian-based localization methods to estimate the position of a target node in indoor deployment scenarios. The measurements are acquired through a distributed antenna system which is connected to a common master anchor node. Each antenna head is affected by different channels parameters, what makes the estimation more difficult. The proposed method combines received signal strength and time of flight measurements to estimate the target location. In our investigations, we also consider a one-level hierarchical Bayesian network model, which introduces conditional interdependencies to the model parameters, resulting in less susceptibility to local variations. The Markov Chain Monte Carlo sampling method is used to approximate the posterior distribution of the two-dimensional target's location coordinates. The root mean square error is used to evaluate the performance of the proposed solution in indoor scenarios. Our results show that by combining hybrid measurements or increasing conditions between the parameters by a hierarchical approach, the proposed mechanisms outperform the classic Bayesian model when estimating the target node using even fewer measurements.
15:30 - 15:40Harmonic Retrieval of CFO and Frame Misalignment for OFDM-based Inter-Satellite Links
Rifat Volkan Senyuva, Gunes Karabulut Kurt.
        As dense low Earth orbit (LEO) constellations are being planned, the need for accurate synchronization schemes in high-speed environments remains a challenging problem to tackle. To further improve synchronization accuracy in channeling environments, which can also be applied in the LEO networks, we present a new method for estimating the carrier frequency offset (CFO) and frame misalignment in orthogonal frequency division multiplexing (OFDM) based inter-satellite links. The proposed method requires the transmission of pilot symbols to exploit 2-D estimation of signal parameters via rotational invariance techniques (ESPRIT) and estimate the CFO and the frame misalignment. The Cramer-Rao lower bounds (CRLB) of the joint estimation of the CFO and frame misalignment are also derived. Numerical results show that the difference between the proposed method and the state-of-art method is less than 5dB at its worse.
16:00 - 17:00
Closing Session : Sławomir Stańczak and Eduard A. Jorswieck