Loop-interference suppression strategies using antenna selection in full-duplex MIMO relays

Abstract

Loop-interference (LI) from relay transmission to reception reduces the channel capacity and makes the relay system unstable in full-duplex (FD) multi-input multi-output (MIMO) relay systems. conventional schemes to suppress LI still have drawbacks: 1) incur a dispensable signal-to-noise ratio (SNR) loss in low SNR regions; 2) increase the system complexity due to the requirement of weighting matrices; and 3) make insufficient practical sense due to varying signal-to-interference ratios (SIRs). In this paper, we propose a new LI suppression scheme using transmit antenna selection in order to solve the above problems. Simulation results show that the proposed scheme outperforms a conventional scheme, especially in low SNR and high SIR regions, even though the proposed scheme has a lower complexity.

Constrained-MMSE Combining for Spatial Domain Self-Interference Cancellation in Full-Duplex Massive MIMO Systems

“…To this end, transceivers must have the capability to transmit and receive signals at the same time and in the same frequency band [1]- [5], which is still a pending technical challenge for practical implementations. However, in the last decade, FD has gained interest in various applications and technologies such as wireless fidelity (WiFi) [6] or relaying [7]- [9]. In fifth generation (5G) networks, FD has been suggested as a solution for integrated access & backhaul (IAB) systems [10], [11] to cope with the densification of the networks, and for non-overlapping sub-band FD (SBFD) to improve the uplink throughput performance [12].…”

“…While a majority of existing works considered the use of beamforming techniques offered by MIMO to improve the performance of FD systems [9], [11], [27]- [30], the core of those SIC methods still resumes in the classic digital domain suppression method where a replica of the SI signal is created and substracted to the actual received signal. One main drawback of this approach is the requirement of a strict time domain synchronization between the replica and the actual received signal since any minor mismatches between these two signals may result in a degradation of the overall performance of the system.…”

“…With such SIC architecture, no SI signal substraction is applied on the received signal but rather a postcoding operation, thus avoiding the aforementioned synchronisation issues of conventional time domain SIC methods. Furthermore, differently from conventional beamforming-based SIC algorithms as those considered in FD relay litterature [7]- [9], our approach relies on the idea of integrating the SI signal as one particular spatial stream between the T x and R x of the FD node for the digital spatial combiner to perform SIC properly. Another originality of our work is the consideration of the spherical wave model (SWM) to model the SI channel contrary to most of the works [9]- [11], [29].…”

“…Furthermore, differently from conventional beamforming-based SIC algorithms as those considered in FD relay litterature [7]- [9], our approach relies on the idea of integrating the SI signal as one particular spatial stream between the T x and R x of the FD node for the digital spatial combiner to perform SIC properly. Another originality of our work is the consideration of the spherical wave model (SWM) to model the SI channel contrary to most of the works [9]- [11], [29]. Since the FD node uses two closely placed antenna array for transmission and reception, the planar wave model (PWM) assumption may indeed not hold anymore as we have shown in [32].…”

Constrained-MMSE Combining for Spatial Domain Self-Interference Cancellation in Full-Duplex Massive MIMO Systems

“…To this end, transceivers must have the capability to transmit and receive signals at the same time and in the same frequency band [1]- [5], which is still a pending technical challenge for practical implementations. However, in the last decade, FD has gained interest in various applications and technologies such as wireless fidelity (WiFi) [6] or relaying [7]- [9]. In fifth generation (5G) networks, FD has been suggested as a solution for integrated access & backhaul (IAB) systems [10], [11] to cope with the densification of the networks, and for non-overlapping sub-band FD (SBFD) to improve the uplink throughput performance [12].…”