Fundamental Relations Between Reactive and Proactive Relay-Selection Strategies

TL;DR

This paper establishes fundamental theoretical relations between reactive and proactive relay-selection strategies in cooperative relay networks, revealing their equivalence in outage probability and differences in symbol error rate, supported by a case study.

Contribution

It proves the equivalence of RRS and PRS in outage probability and compares their symbol error rates, providing new insights into relay-selection strategies.

Findings

RRS and PRS are equivalent in end-to-end outage probability.

RRS outperforms PRS in end-to-end symbol error rate.

Case study confirms theoretical relations under interference and noise.

Abstract

Two major relay-selection strategies widely applied in cooperative decode-and-forward (DF) relaying networks, namely, reactive relay selection (RRS) and proactive relay selection (PRS), are generally looked upon as independent and studied separately. In this paper, RRS and PRS are proven to be equivalent with respect to the end-to-end outage probability from the first principle, i.e. their respective relay-selection criteria. On the other hand, RRS is shown to be superior to PRS with respect to the end-to-end symbol error rate. Afterwards, a case study of a general DF relaying system, subject to co-channel interferences and additive white Gaussian noise at both the relaying nodes and the destination, is performed to explicitly illustrate the aforementioned outage equivalence. These fundamental relations provide intuitive yet insightful performance benchmarks for comparing various applications of these two relay-selection strategies.