Differential Modulation for Bi-directional Relaying with Analog Network Coding

TL;DR

This paper introduces an analog network coding scheme with differential modulation for bidirectional relay networks that do not require channel state information, analyzing its performance and optimizing power allocation.

Contribution

It presents a novel ANC-DM scheme for bidirectional relaying without CSI, including performance analysis and power optimization strategies.

Findings

BER performance is about 3 dB worse than coherent detection.

Optimal power allocation improves BER by 1-2 dB.

Analytical BER results match simulation outcomes.

Abstract

In this paper, we propose an analog network coding scheme with differential modulation (ANC-DM) using amplify-and-forward protocol for bidirectional relay networks when neither the source nodes nor the relay knows the channel state information (CSI). The performance of the proposed ANC-DM scheme is analyzed and a simple asymptotic bit error rate (BER) expression is derived. The analytical results are verified through simulations. It is shown that the BER performance of the proposed differential scheme is about 3 dB away from that of the coherent detection scheme. To improve the system performance, the optimum power allocation between the sources and the relay is determined based on the simplified BER. Simulation results indicate that the proposed differential scheme with optimum power allocation yields 1-2 dB performance improvement over an equal power allocation scheme.