Sum-Rate Analysis and Optimization of Self-Backhauling Based Full-Duplex Radio Access System

TL;DR

This paper analyzes a full-duplex radio access system with self-backhauling, deriving sum-rate expressions, optimizing performance, and demonstrating that full-duplex relaying outperforms half-duplex schemes for maximizing sum-rate.

Contribution

It provides a comprehensive sum-rate analysis and optimization framework for self-backhauling full-duplex systems with massive arrays, highlighting the benefits over half-duplex methods.

Findings

Full-duplex access nodes improve sum-rate compared to half-duplex.

Relay-type full-duplex schemes achieve the highest sum-rate.

Self-interference nulling with massive arrays enhances system performance.

Abstract

In this article, a radio access system with a self-backhauling full-duplex access node serving legacy half-duplex mobile devices is studied and analyzed. In particular, it is assumed that the access node is using the same center frequency for all the transmissions, meaning that also the backhauling is done using the same frequency resources as the uplink and downlink transmissions. It is further assumed that the access node has a massive array to facilitate efficient beamforming and self-interference nulling in its own receiver. As a starting point, the signal model for the considered access node is first derived, including all the transmitted and received signals within the cell. This is then used as a basis for obtaining the sum-rate expressions, which depict the overall rates experienced by the mobile users that are served by the access node. In addition, the data rate for the bi-directional backhaul link is also derived, since the access node must be able to backhaul itself wirelessly. The maximum achievable sum-rate is then determined by numerically solving an optimization problem constructed from the data rate expressions. The full-duplex scheme is also compared to two alternative transmission schemes, which perform all or some of the transmissions in half-duplex mode. The results show that the full-duplex capability of the access node is beneficial for maximizing the sum-rate, meaning that a simple half-duplex transmission scheme is typically not optimal. In particular, the highest sum-rate is usually provided by a relay type solution, where the access node acts as a full-duplex relay between the mobiles and the backhaul node.