Full-Duplex Relaying in MIMO-OFDM Frequency-Selective Channels with Optimal Adaptive Filtering

TL;DR

This paper introduces an adaptive filtering technique using RLS algorithms for full-duplex MIMO-OFDM relays to effectively cancel self-interference, significantly improving relay performance in frequency-selective channels.

Contribution

It proposes a novel time-domain self-interference cancellation method employing RLS for broadband MIMO-OFDM relays, enhancing interference mitigation capabilities.

Findings

The RLS-based method converges rapidly, within the duration of OFDM sequences.

The proposed technique extends the interference resilience range of the relay.

Simulation results show improved BER and SINR performance.

Abstract

In-band full-duplex transmission allows a relay station to theoretically double its spectral efficiency by simultaneously receiving and transmitting in the same frequency band, when compared to the traditional half-duplex or out-of-band full-duplex counterpart. Consequently, the induced self-interference suffered by the relay may reach considerable power levels, which decreases the signal-to-interference-plus-noise ratio (SINR) in a decode-and-forward (DF) relay, leading to a degradation of the relay performance. This paper presents a technique to cope with the problem of self-interference in broadband multiple-input multiple-output (MIMO) relays. The proposed method uses a time-domain cancellation in a DF relay, where a replica of the interfering signal is created with the help of a recursive least squares (RLS) algorithm that estimates the interference frequency-selective channel. Its convergence mean time is shown to be negligible by simulation results, when compared to the length of a typical orthogonal-frequency division multiplexing (OFDM) sequences. Moreover, the bit-error-rate (BER) and the SINR in a OFDM transmission are evaluated, confirming that the proposed method extends significantly the range of self-interference power to which the relay is resilient to, when compared with other mitigation schemes.