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 the 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 time domain rather than frequency domain, which allows to increase the amount of UL transmission opportunity, as compared to TDD where majority of time slots are used for DL. Concurrent UL and DL transmission create different types of interference, which makes cancellation approaches essential for an 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 baseline. The results indicate four times increase of UL throughput for cell-edge users as well as 32% and 6% increase of average UL throughput, at low and medium load, respectively. Furthermore, simulation results determine that at least 149 dB of self-interference mitigation is required for an acceptable performance in SBFD. Results also show that SBFD benefits are limited by inter-site gNB-to-gNB interference.