Modeling and System-Level Performance Evaluation of Sub-Band Full Duplexing for 5G-Advanced

This article presents sub-band full duplex (SBFD) as a duplexing scheme to improve the uplink (UL) throughput in 5G-Advanced networks, as an alternative to traditional time-division duplexing (TDD). SBFD provides opportunities to transmit and receive simultaneously on non-overlapping frequency resources. To accomplish this, SBFD time slots include both UL and downlink (DL) transmission. This leads to UL transmission being more expanded in the time domain rather than the frequency domain, which allows to increase the amount of UL transmission opportunities, as compared to TDD where the majority of time slots are used for DL. Concurrent UL and DL transmission create different types of interference, which makes cancellation approaches essential for appropriate performance. The SBFD interference types, including self-interference as the main challenge of SBFD deployment, are outlined and corresponding analytical models are proposed to provide a realistic evaluation of SBFD performance. System-level simulations with different load conditions in a high-power urban macro environment are used to evaluate the SBFD performance in comparison with TDD as the baseline. The results indicate a four times increase in the UL throughput for cell-edge users as well as 32% and 6% increase in average UL throughput, at low and medium loads, respectively. Furthermore, simulation results determine that at least 149 dB of self-interference mitigation is required for acceptable performance in SBFD. Results also show that SBFD benefits are limited by inter-site gNB-to-gNB interference.