A Novel Game Theoretic Approach for Energy Efficient Modulation in MC-DS-CDMA

In this paper a game theoretic approach to study the effect of constellation size on energy efficiency of MC DS CDMA system for M-QAM modulation is studied. A non cooperative game is proposed in which each user seeks to choose its transmit power, 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 it is particularly suitable for energy-constrained networks. It is shown that in order to maximize the user's utility, a user must choose the lowest constellation size that can accommodate the user's delay constraint. This strategy is different from one that could maximize spectral efficiency. Using this approach, the trade offs among energy efficiency, delay, throughput and constellation size are also studied and quantified. The effect of Trellis coded modulation on energy efficiency is discussed additionally