Differential Dual-Hop Relaying under User Mobility

TL;DR

This paper analyzes differential dual-hop relaying over time-varying Rayleigh channels, revealing limitations of two-symbol detection in fast fading and proposing a multiple-symbol detection method that significantly enhances performance.

Contribution

It provides a theoretical analysis of differential detection methods in fast-fading channels and introduces a practical multiple-symbol detection scheme with improved robustness.

Findings

Two-symbol differential detection degrades in fast-fading channels.

An irreducible error floor exists at high SNR with two-symbol detection.

Multiple-symbol detection significantly improves performance in fast-fading scenarios.

Abstract

This paper studies dual-hop amplify-and-forward relaying system employing differential encoding and decoding over time-varying Rayleigh fading channels. First, the convectional "two-symbol" differential detection (CDD) is theoretically analysed in terms of the bit-error-rate (BER). The obtained analysis clearly shows that performance of two-symbol differential detection severely degrades in fast-fading channels and reaches an irreducible error floor at high signal-to-noise ratio region. To overcome the error floor experienced with fast-fading, a practical suboptimal "multiple-symbol" detection (MSD) is designed and its performance is theoretically analysed. The analysis of CDD and MSD are verified and illustrated with simulation results under different fading scenarios. Specifically, the obtained results show that the proposed MSD can significantly improve the system performance in fast-fading channels.