A Game-Theoretic Approach to Energy-Efficient Modulation in CDMA Networks with Delay QoS Constraints

TL;DR

This paper presents a game-theoretic framework for optimizing constellation size and power in CDMA networks to maximize energy efficiency under delay QoS constraints, revealing that users should choose the smallest feasible constellation size.

Contribution

It introduces a non-cooperative game model for energy-efficient modulation with delay constraints and derives the Nash equilibrium strategies for constellation size and power.

Findings

Users should select the lowest constellation size satisfying delay constraints.

The framework quantifies tradeoffs among energy efficiency, delay, throughput, and constellation size.

Trellis-coded modulation's impact on energy efficiency is analyzed.

Abstract

A game-theoretic framework is used to study the effect of constellation size on the energy efficiency of wireless networks for M-QAM modulation. A non-cooperative game is proposed in which each user seeks to choose its transmit power (and possibly transmit symbol rate) as well as the constellation size in order to maximize its own utility while satisfying its delay quality-of-service (QoS) constraint. The utility function used here measures the number of reliable bits transmitted per joule of energy consumed, and is particularly suitable for energy-constrained networks. The best-response strategies and Nash equilibrium solution for the proposed game are derived. It is shown that in order to maximize its utility (in bits per joule), a user must choose the lowest constellation size that can accommodate the user's delay constraint. This strategy is different from one that would maximize spectral efficiency. Using this framework, the tradeoffs among energy efficiency, delay, throughput and constellation size are also studied and quantified. In addition, the effect of trellis-coded modulation on energy efficiency is discussed.