Full-duplex Multi-Antenna Relay Assisted Cooperative Non-Orthogonal Multiple Access

TL;DR

This paper investigates a full-duplex multi-antenna relay in a cooperative NOMA network, analyzing outage probabilities under imperfect interference cancellation, and demonstrates performance gains over half-duplex systems with different user selection strategies.

Contribution

It introduces a zero-forcing beamforming scheme for SI cancellation at a full-duplex relay and compares two user selection strategies, highlighting performance improvements over half-duplex relays.

Findings

Full-duplex relay significantly outperforms half-duplex systems.

Nearest near and far user selection strategy yields better outage performance.

Performance gains depend on user density, zones, path loss, and interference strength.

Abstract

We consider a cooperative non-orthogonal multiple access (NOMA) network in which a full-duplex (FD) multi-antenna relay assists transmission from a base station (BS) to a set of far users with poor channel conditions, while at the same time the BS transmits to a set of near users with strong channel conditions. We assume imperfect self-interference (SI) cancellation at the FD relay and imperfect inter-user interference cancellation at the near users. In order to cancel the SI at the relay a zero-forcing based beamforming scheme is used and the corresponding outage probability analysis of two user selection strategies, namely random near user and random far user (RNRF), and nearest near user and nearest far user (NNNF), are derived. Our finding suggests that significant performance improvement can be achieved by using the FD multi-antenna relay compared to the counterpart system with a half-duplex relay. The achieved performance gain depends on network parameters such as the user density, user zones, path loss and the strength of the inter-user interference in case of near users. We also show that the NNNF strategy exhibits a superior outage performance compared to the RNRF strategy, especially in the case of near