JOINT NETWORK-CENTRIC USER-CENTRIC POWER CONTROL GAME FOR MULTI-CARRIER CDMA NETWORKS

Abstract

With the increasing need for high-speed data transfer, multimedia and streaming video, the next generation 4G systems will incorporate complex physical layer techniques which will be considerably more demanding. Multi-carrier CDMA (MC-CDMA) systems are one of the potential candidate for 4G wireless systems and will be based on a combination of Orthogonal Frequency Division Multiplexing (OFDM) and Code Division Multiple Access (CDMA) schemes. Power control is one of the most important radio resource management tools for any wireless system. A good power control scheme ensures the efficient use of radio resources and helps the users in attaining various Quality of Service (QOS) requirements. In this dissertation work, non cooperative game theory has been utilized to solve the power control problem for MC-CDMA systems. In a wireless network, a user wants to achieve a high value of SINR at the lowest possible value of transmit power. In this highly user-centric approach, all users act selfishly to maximize their achieved utility. However, from a network-centric point of view, the network being the global player tries to accommodate as many players as possible. Here, we have considered a joint network-centric user-centric (NC-UC) power control game where the users try to optimize their powers so as to achieve the maximum possible value of utility, whereas the network tries to optimize the revenue it receives from players. The net result is a solution that lies between the two extreme solutions of pure network-centric and user-centric goals. Simulations performed for a pure user-centric power control game show that the equilibrium is inefficient and an increase in net utilities is achieved by introducing pricing into the system. This is evident from the increased utility values in a joint NC-UC power control game. Moreover, proportionality holds between the QOS achieved by the user and the payment it makes i.e. users with better channel gains get better services but they pay proportionally more. The net utilities are found to be varying non-linearly with a linear increase in the number of carriers for both user-centric and joint NC-UC power control games.