Resilient communication in mmWave and THz communication based on IAB and RIS

5th generation (5G) and 6th generation (6G) are significant wireless technology advancements that are expected to operate on millimeter wave (mmWave) and sub-Terahertz (THz) spectrum, respectively. While 5G significantly improved data speeds and connectivity, 6G is anticipated to go even further by enabling even higher frequencies and superior performance, making it a key enabler for meeting the requirements of future digital applications for higher data rates and bandwidth. In the context of 5G and future generations like 6G, resilience becomes even more critical as these networks support a wide range of applications, including mission-critical services, IoT, and autonomous systems, where uninterrupted communication is essential. In the first phase of thesis, first we summarize SOA channel modeling approaches in sub- THz. Then we introduce two novel channel modeling approaches -THz-GAN channel and Simplified Stochastic Channel Model in THz (SSCH-THz)- at 140 GHz, based on statistical and ML-based to cope with the usefulness of conventional channel modeling approaches in the THz spectrum and the absence of general channel modeling at this spectrum. In order to validate channel models we implement proposed channel models and benchmarks in ns-3 in order to validate channels and enable full-stack performance of applications like UDP and TCP based on KPI performance metrics. The results indicate that with 1000 fewer training steps and a smaller required dataset size, the THz-GAN channel and the benchmark channel models KPI are extremely similar, with a maximum CIR difference of 10 dBm. On the other hand, Integrated Access and Backhaul (IAB) and RIS are flexible and low-cost solutions to deploy ultra-dense fifth and sixth-generation (5G and 6G) systems, as they enable wireless backhaul links based on the same technology and specifications as for the access link. In the second phase, we introduce new system level simulator on top of sionna to support IAB network and self-bakhauling and SAFEHAUL: novel RL-based backhaul schedular. Then, we profile RIS performance by implementing RIS signal model in ns-3 mmwave. Then, we consider the deployment of mixed mmWave and sub-terahertz links to increase the capacity of the backhaul network, and provide the first performance evaluation of the potential of sub-terahertz frequencies for 5G and 6G Integrated Access and Backhaul (IAB). Our results show that IAB with sub-terahertz links can outperform a mmWave-only deployment with improvements of 4× for average user throughput and a reduction of up to 50% for median latency.