PHY8 – Beyond 5G

Thursday, 8 June 2023, 16:00-17:30, Room J1

Session Chair: Charitha Madapatha (Chalmers University of Technology, Sweden)

Non-Geometric Correlated Channel Fading Model with Linear Complexity
Tobias W Weber (SEW-Eurodrive, Germany); Eike Lyczkowski (SEW-EURODRIVE, Germany); Wolfgang Kiess (University of Applied Sciences Koblenz, Germany)
Simulations are an important component for the investigation of wireless technologies. Thereby, a compute efficient channel model is needed for simulations of the physical layer. For the investigation of packet duplication a fading model with correlated channels is of high importance. We propose such a complexity-optimized fading model whose parameters fading strength, autocorrelation and channel correlation can be adjusted with fine granularity. The model is based on the sum of sinusoids method and includes Rayleigh distributed small scale fading and normal distributed large scale fading. The model is validated for its mathematical properties within a wide parameter range and its source code is published

Autonomous Single Antenna Receiver Localization and Tracking with RIS and EKF
Zi Ye and Faryal Junaid (Luleå Tekniska Universitet, Sweden); Rickard Nilsson and Jaap van de Beek (Luleå University of Technology, Sweden)
Single antenna sensors in the rapidly emerging Internet-of-Things (IoT) are attractive due to their simplicity and low cost. However, determining their own positions autonomously using only a single antenna is challenging. This paper presents a novel approach for autonomous downlink localization of singleantenna receivers using Reconfigurable Intelligent Surfaces (RIS) and a tracking process using the complex extended Kalman filter (EKF). Simulation results show that the considered RISaided wireless radio system can provide accurate localization and continuous fast tracking down to the centimeter level, especially when multiple RISs are deployed. Furthermore, various factors affecting the system performance are analyzed in detail.

Reduced Complexity Multicast Beamforming and User Grouping for Multi-Antenna Coded Caching
Shanuka Gamaethige, Hamidreza Bakhshzad Mahmoodi and MohammadJavad Salehi (University of Oulu, Finland); Himal A Suraweera (University of Peradeniya, Sri Lanka); Antti Tölli (University of Oulu, Finland)
A new user-grouping method for multiantenna coded caching (CC) is proposed, able to simultaneously exploit spatial multiplexing, multicasting, and global caching gains. The proposed scheme achieves the theoretical optimal sum degrees of freedom (DoF) and can be applied to networks with any number of users K, transmit antennas L, and global CC gain t. The proposed scheme comprises both multicast and unicast transmissions wherein a suitable combination of messages is chosen exploiting a tree diagram structure thus guaranteeing symmetric transmission of data for any given set of network parameters. The same structure also removes the successive interference cancellation requirement at the receivers, thus enabling a simple linear design for optimized beamformers. Moreover, even though the proposed scheme in general requires a larger subpacketization than the original single antenna CC scheme, for the particular case of t+L/t+1 ∈ N, it works with exactly the same subpacketization value. Finally, the achievability of the proposed scheme is proven, and in the simulations, it is demonstrated that the complexity of the transmitter and receiver implementations can be greatly reduced with only a modest performance loss.

Large Intelligent Surface Measurements for Joint Communication and Sensing
Christian Nelson and Xuhong Li (Lund University, Sweden); Benjamin J. B. Deutschmann, Klaus Witrisal and Thomas Wilding (Graz University of Technology, Austria); Fredrik Tufvesson (Lund University, Sweden)
Multiple concepts for future generations of wireless communication standards utilize coherent processing of signals from many distributed antennas. Names for these concepts include distributed MIMO, cell-free massive MIMO, XL-MIMO, and large intelligent surfaces. They aim to improve communication reliability, capacity, as well as energy efficiency and provide possibilities for new applications through joint communication and sensing. One such recently proposed solution is the concept of RadioWeaves. It proposes a new radio infrastructure for distributed MIMO with distributed internal processing, storage and compute resources integrated into the infrastructure. The large bandwidths available in the higher bands have inspired much work regarding sensing in the mmWave- and sub-THzbands, however, sub-6 GHz cellular bands will still be the main provider of broad cellular coverage due to the more favorable propagation conditions. In this paper, we present results from a sub-6 GHz measurement campaign targeting the non-stationary spatial channel statistics for a large RadioWeave and the temporal non-stationarity in a dynamic scenario with RadioWeaves. From the results, we also predict the possibility of multi-static sensing and positioning of users in the environment.

Dynamic AP Selection and Cluster Formation with Minimal Switching for Green Cell-Free Massive MIMO Networks
Qinglong He (KTH Royal Institute of Technology, Sweden); Özlem Tuğfe Demir (TOBB University of Economics and Technology, Turkey); Cicek Cavdar (KTH Royal Institute of Technology, Sweden)
Aiming at the implementation of energy-efficient cell-free networks, several approaches have been proposed in the literature, which consider different access point (AP) switch ON/OFF (ASO) strategies for power minimization. Different from prior works, this paper focuses on additional factors that have an adverse effect not only on total power consumption but also on implementation complexity and operation cost. For instance, too frequent ON/OFF switching in an AP can lead to tapering off the potential power saving of ASO by incurring extra power consumption due to excessive switching. Indeed, frequent switching of APs might also result in thermal fatigue and severe lifetime degeneration. Moreover, time variations in the AP-UE (user equipment) clusters in favor of energy saving in a dynamic network bring additional signaling and implementation complexity. Thus, we propose a multi-objective optimization problem that aims to minimize the total power consumption together with AP switching and AP-UE clustering variations in comparison to the previous state of the network. The proposed problem is cast in mixed integer quadratic programming form and solved optimally. Our simulation results show that by limiting AP switching (node switching) and AP-UE cluster reformation switching (link switching), the total power consumption at the radio site only slightly increases, but the number of average switching drops significantly regardless of node or link switching. It achieves a good balance on the trade-off between radio power consumption and the side effects excessive switching will bring.

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