hi-STAR

Deliverable 5.2: Edge control center for optimal user traffic distribution This deliverable is a result of the work done in WP5 Subactivity T5.2 – Network core edge functions research and development. Deliverable D5.2 presents architectural and functional survey and analysis of edge computing used for enhancing quality of service and experience (QoS, QoE) for end users. Edge computing has been recognized as an important pillar for improving quality of provided services and meeting high demands especially regarding very low latency and bandwidth efficient usage. In this deliverable, we discuss the possibilities to use edge computing to optimally distribute user traffic by notifying users which RAT is more suitable for specific services.

Paper published in journal Entropy P. Ivaniš, J. Milojković, V. Blagojević, and S. Brkić. "Capacity Analysis of Hybrid Satellite–Terrestrial Systems with Selection Relaying" Entropy 26, no. 5: paper n0. 419, May 2024. (web: https://lnkd.in/dNMU7rVh, DOI: 10.3390/e26050419, impact factor: 2.1). In this paper, we analyze a system where the satellite–terrestrial links undergo shadowed Rice fading, and, following this, terrestrial relay applies the selection relaying protocol and forwards the information to the final destination using the communication link subjected to Nakagami-m fading. The presented numerical results illustrate the usefulness of the selection relaying for various propagation scenarios and system geometry parameters.

Deliverable 5.1: Functional network core gateway for PoC This deliverable is a result of the work done in WP5 Subactivity T5.1 – Network core functions and gateway design and development. Deliverable D5.1 presents a functional gateway that connects to network cores of terrestrial and satellite RATs to enable ATSSS (Access Traffic Steering, Switching and Splitting) functions to users that have the possibility on their devices to connect to these two RATs. The purpose of the gateway is to enable persistent, robust and reliable TCP (Transmission Control Protocol) sessions to users prone to handovers and/or loss of connection over one of the RATs. This deliverable also discusses UDP (User Datagram Protocol) traffic from ATSSS and end user points of view. Discussion regarding possible approaches in enabling ATSSS support is given as well.

Deliverable 4.2: Simulation and verification of the ITCU module This deliverable is a result of the work done in the context of WP4 Subtasks T4.1 (Simulation environment creation) and T4.2 (Design of traffic control module placed in HUT). We briefly review the simulation environment that includes LEO (Low Earth Orbit) satellite-to-ground communication links and a user-centric handover execution method. Following this, a description of the expert system based on various machine learning (ML) models including (neural networks) is given, alongside the dataset containing the simulations for its evaluation. A comparison between various ML models is given, and a review of system performance in terms of two types of adaptive coding and modulation scenarios.

Deliverable 3.2: FPGA-based accelerators for high-performance 5G/Sat transceivers This deliverable is a result of the work done in the context of WP3 Subtask T3.2 – 5G and DVB-S2X protocol implementation using HW/SW co-design. Deliverable D3.2 presents developed FPGA hardware accelerators for both physical layers.

Deliverable 2.3: Reliability analysis of 5G/Sat hybrid network This deliverable is a result of the work done in the context of WP2 Subtask T2.2 (Reliability analysis of integrated terrestrial and satellite links). We briefly presented the outage analysis of the hybrid integrated satellite-terrestrial communication systems. First, we discussed the case where the reliability of the system is increased by using cooperative relaying, and the analysis takes into account the system geometry and realistic channel parameters. Finally, we present a novel framework for designing decoders, for Low-Density Parity-Check (LDPC) codes, which surpasses the frame error rate performance of Belief-Propagation (BP) decoding. Its key component is the adaptation method, based on the genetic optimization algorithm.

Award for the best journal paper in the area of Telecommunications Our paper, published in the Sensors journal: A. Cvetković, V. Blagojević, J. Anastasov, N. T. Pavlović, and M. Milošević, "Outage Analysis of Unmanned-Aerial-Vehicle-Assisted Simultaneous Wireless Information and Power Transfer System for Industrial Emergency Applications", Sensors vol. 23, no. 18, paper no. 7779, September 2023, was selected as the best paper in the area of Telecommunications published in scientific journal in year 2022/2023.

Paper is presented at the international conferences TELSIKS 2023 Jovan Milojković, Srđan Brkić, Predrag Ivaniš and Zoran Čiča: “Performance of Handover Execution in Satellite Networks with Shadowed-Rician Fading ”, Telsiks, 16th International Conference on Advanced Technologies, Systems and Services in Telecommunications, 25-27. Oktobar 2023, Niš, pp. 155-158 In this paper we analyze a user-centric handover procedure, which can be used to improve the downstream communication from low Earth orbit satellite network to end users, in presence of shadowed-Rician fading. We consider usage of DVB-S2X protocol and numerically express the improvement, measured by average spectral efficiency and data loss rate, achievable with employment of multiple satellites. The improvement is a consequence of the proposed strategy to predict the signal-to-noise ratio in the considered communication channel.

Invited paper is presented at the international conferences TELSIKS 2023 Ivan Stanić, Dejan Drajić, Zoran Čiča: “Overview of Network Selection and Vertical Handover Approaches and Simulation Tools in Heterogeneous Wireless Networks”, Telsiks, 16th International Conference on Advanced Technologies, Systems and Services in Telecommunications, 25-27. Oktobar 2023, Niš, pp. 133-142 Wireless communications constitute a vital sector within telecommunications. Multiple wireless technologies, such as 4G, 5G, WiFi, etc., are available to users. One of the most important benefits of wireless communications is enabling user mobility. However, this feature often requires handover between access points or base stations. Moreover, modern user equipment has the support for multiple wireless technologies, which brings the possibility for network selection and vertical handover (VHO) between different wireless technologies. The importance of network selection and VHO has been further amplified in recent years because satellite communications are increasingly perceived as extensions to terrestrial wireless technologies. This invited paper provides a comprehensive review of the current state-of-the-art methods, algorithms and techniques used in network selection and VHO. It delves into the underlying mathematical approaches and models that underpin each method. Detailed performance comparison with listed advantages and disadvantages of the analyzed methods is also presented in the paper.

Paper is presented at the international conferences ICTON 2023:* G. T. Djordjevic and I. B. Djordjevic, "Effect of Pointing Errors on BER Performance of Multidimensional LDPC-Coded OAM Modulation with Direct Detection over Turbulent FSO Channels," *2023 23rd International Conference on Transparent Optical Networks (ICTON)*, Bucharest, Romania, 2023, pp.1-4, doi: 10.1109/ICTON59386.2023.10207427. In this invited paper, we study orbital angular momentum (OAM) - based signal transmission over free-space optical (FSO) link. After low-density parity-check (LDPC) encoding and multidimensional mapping, intensity modulation is implemented, and OAM multiplexing is performed. Signal is transmitted over FSO channel with atmospheric turbulence, pointing errors, and atmospheric loss. At the receiver end, signal is firstly demultiplexed by OAM demultiplexer, detected by photodiode, and further decoded by applying the multidimensional posterior-probability demapper and LDPC decoder. The bit-error rate (BER) performances are estimated by Monte Carlo simulations. The numerical results show that even when there is a strong misalignment between transmitter and receiver apertures, BER of the system can be reduced by applying appropriate quasi-cyclic LDPC codes. We show that BER values under 10 -6 can be achieved for some typical values of electrical energy per information bit - to - noise spectral density ratio even when turbulence is strong.