Design and Analysis of Wideband In-Band-Full-Duplex FR2-IAB Networks

Abstract

This paper develops a 3GPP inspired design for the in-band-full-duplex (IBFD) Integrated Access and Backhaul (IAB) networks in the frequency range 2 (FR2) band, which can enhance the spectral efficiency (SE) and coverage while reducing the latency. However, the self-interference (SI), which is usually more than 100 dB higher than the signal-of-interest, becomes the major bottleneck in developing these IBFD networks. With the estimated RF effective channel obtained via RF codebooks given by our modified Linde-Buzo-Gray (LBG) algorithm, we design and analyze a subarray-based hybrid precoding FD-IAB system. The SI is canceled in three stages, where the antenna isolation forms the first stage and is assumed to be achieved. The second stage consists of the fiber-Bragg-grating (FBG)-based RF cancellation, where the cancelers are connected with the RF chain pairs. The third stage comprises the digital cancellation via successive interference cancellation followed by minimum mean squared error (MMSE) baseband receiver. Multiuser interference in the access link is canceled by zero-forcing at the IAB-node transmitter. Simulations show that our staged SI cancellation can enhance the SE. Moreover, the residual SI due to the hardware impairments and channel uncertainty can affect the SE of the FD scheme in the backhaul link.