A simple near‐optimal path selection scheme for multi‐hop wireless relay networks based on Viterbi algorithm

In a multi-hop wireless relay network, the optimal path selection scheme with exhaustive path search entails high-implementation complexity and is impractical when the number of hops is large. In this paper, we propose a near-optimal low-complexity path selection scheme, based on amplify-and-forward protocol, whose outage performance is close to the optimal path selection scheme. The proposed scheme draws on the analogy between the node distribution of a commonly used relay network model and the trellis of a convolutional code and applies the Viterbi algorithm in selecting a path to minimise the end-to-end outage probability. To save memory and reduce the time delay in distributed implementation, the sliding window Viterbi algorithm is assumed. For reference purpose, an asymptotic lower bound of the outage probability is first derived for the optimal path selection scheme. Then an approximated outage probability expression of the proposed scheme is derived. These analytical expressions are verified by simulations to be accurate at high signal-to-noise ratios. It is revealed that when the window size is reasonably large, the proposed scheme achieves almost the same outage performance as the optimal path selection scheme at high signal-to-noise ratios. The proposed scheme has polynomial complexity and small memory storage requirement. Therefore, it is very efficient for large-scale relay networks. Copyright © 2014 John Wiley & Sons, Ltd.