Optimal Relay Selection with Non-negligible Probing Time

TL;DR

This paper introduces an optimal relay selection algorithm for cooperative wireless networks that accounts for non-negligible probing times, balancing bandwidth efficiency and diversity order through a threshold-based stopping rule.

Contribution

It proposes a novel relay selection strategy with a simple threshold structure that optimally balances probing time and relay performance in complex networks.

Findings

Achieves full diversity order and high bandwidth efficiency.

Provides a stopping rule for relay probing that optimizes selection.

Validates the strategy through analytical and simulation results.

Abstract

In this paper an optimal relay selection algorithm with non-negligible probing time is proposed and analyzed for cooperative wireless networks. Relay selection has been introduced to solve the degraded bandwidth efficiency problem in cooperative communication. Yet complete information of relay channels often remain unavailable for complex networks which renders the optimal selection strategies impossible for transmission source without probing the relay channels. Particularly when the number of relay candidate is large, even though probing all relay channels guarantees the finding of the best relays at any time instant, the degradation of bandwidth efficiency due to non-negligible probing times, which was often neglected in past literature, is also significant. In this work, a stopping rule based relay selection strategy is determined for the source node to decide when to stop the probing process and choose one of the probed relays to cooperate with under wireless channels' stochastic uncertainties. This relay selection strategy is further shown to have a simple threshold structure. At the meantime, full diversity order and high bandwidth efficiency can be achieved simultaneously. Both analytical and simulation results are provided to verify the claims.