Energy Efficient Cooperative Network Coding with Joint Relay Scheduling and Power Allocation

TL;DR

This paper investigates energy-efficient multi-relay network coding by jointly optimizing relay scheduling and power allocation, demonstrating significant energy efficiency gains through a convex optimization approach under outage constraints.

Contribution

It introduces a novel joint relay scheduling and power allocation framework for energy-efficient network coding, with a convex approximation and iterative solution method for complex optimization.

Findings

MDNC achieves higher EE than NoNC with the same relays.

RS enhances EE gains significantly in MDNC.

Trade-offs between EE and outage probability are characterized.

Abstract

The energy efficiency (EE) of a multi-user multi-relay system with the maximum diversity network coding (MDNC) is studied. We explicitly find the connection among the outage probability, energy consumption and EE and formulate the maximizing EE problem under the outage probability constraints. Relay scheduling (RS) and power allocation (PA) are applied to schedule the relay states (transmitting, sleeping, \emph{etc}) and optimize the transmitting power under the practical channel and power consumption models. Since the optimization problem is NP-hard, to reduce computational complexity, the outage probability is first tightly approximated to a log-convex form. Further, the EE is converted into a subtractive form based on the fractional programming. Then a convex mixed-integer nonlinear problem (MINLP) is eventually obtained. With a generalized outer approximation (GOA) algorithm, RS and PA are solved in an iterative manner. The Pareto-optimal curves between the EE and the target outage probability show the EE gains from PA and RS. Moreover, by comparing with the no network coding (NoNC) scenario, we conclude that with the same number of relays, MDNC can lead to EE gains. However, if RS is implemented, NoNC can outperform MDNC in terms of the EE when more relays are needed in the MDNC scheme.