Selective Cooperative Relaying over Time-Varying Channels

TL;DR

This paper analyzes relay switching rates in selective cooperative relaying over time-varying channels, deriving formulas and comparing schemes to improve performance in fast fading environments.

Contribution

It provides closed-form expressions for relay switching rates and activation times for OR and DSSC schemes in time-varying channels, highlighting DSSC's advantages.

Findings

DSSC has lower relay switching rates than OR.

DSSC exhibits longer average relay activation times.

Numerical results confirm DSSC's suitability for fast fading environments.

Abstract

In selective cooperative relaying only a single relay out of the set of available relays is activated, hence the available power and bandwidth resources are efficiently utilized. However, implementing selective cooperative relaying in time-varying channels may cause frequent relay switchings that deteriorate the overall performance. In this paper, we study the rate at which a relay switching occurs in selective cooperative relaying applications in time-varying fading channels. In particular, we derive closed-form expressions for the relay switching rate (measured in Hz) for opportunistic relaying (OR) and distributed switch and stay combining (DSSC). Additionally, expressions for the average relay activation time for both of the considered schemes are also provided, reflecting the average time that a selected relay remains active until a switching occurs. Numerical results manifest that DSSC yields considerably lower relay switching rates than OR, along with larger average relay activation times, rendering it a better candidate for implementation of relay selection in fast fading environments.