Decode-and-Forward Relaying Protocol with Optimal Degrees of Freedom for Proactively Selective Wireless Relay Networks

Abstract

This paper proposes a new decode-and-forward relaying protocol for wireless relay networks with relay selection to maximize the end-to-end instantaneous capacity. The main idea is to optimize the degrees of freedom, which may be time, frequency, or both time and frequency, and are unoptimized in the conventional decode-and-forward relaying protocol. Without loss of generality, we focus on optimizing the time of relaying phases, namely, the source-to-relay phase, and the relay-to-destination phase. We proved that the proposed protocol always yield greater end-to-end instantaneous capacity than or equal to that of the conventional protocol, and also proved that the proposed protocol sometimes select the relay node, different from the relay node selected by the conventional protocol. The conventional and the proposed protocols are compared in terms of ergodic capacity and outage probability by computer simulations. The comparisons show that the proposed relaying protocol performs better than the conventional relaying protocol in all signal-to-noise ratio regimes.