Performance Analysis of a Multi-Hop Communication System with Decode-and-Forward Relaying

This paper analyzes the performance of a multi-hop wireless communication system, consisting of a source node, N intermediate nodes or relays, and a destination node in a Rayleigh fading environment with decode-and-forward relaying at each intermediate node. The data is therefore transmitted from source to destination through N+1 hops. Two types of modulation, namely, M-ary phase-shift keying (MPSK) and orthogonal M-ary frequency-shift keying (OMFSK), are considered for the transmitted data. In case of MPSK, each relay performs coherent detection, while in case of OMFSK, each relay performs non-coherent detection. Using a difference equation approach, analytical expressions for the end-to-end symbol error probability are derived in both cases. We find that (1) although the performance degrades with increasing number of hops for fixed average signal-to-noise ratio per hop, the incremental degradation in performance with the addition of each extra hop decreases, (2) when each node transmits with fixed power, multi-hop transmission offers significant performance improvement over direct transmission.