Joint Power And Rate Control Based On Game Theory In CDMA System

In order to transmit and receive multi-media information, The Third Generation Mobile Communication System Should support high bit-rate services. In theory, FDMA, TDMA and CDMA all can be used in 3G. Because CDMA communication system with power control has some merits such as high capacity, anti-interference and lower transmitting power etc. The 3G composed mainly of W-CDMA、CDMA2000 takes CDMA as its multi-access scheme.Because of multi-access interference, power control has become a key technology in CDMA communication system. In order to support multi-application services, the unitary power control method could not further advance the performance of CDMA system, combined power control is becoming a hot topic in research area.Traditional power control algorithm in CDMA is oriented to voice service. It can be divided into two kinds--distributed and centralized power control algorithm.The centralized power control algorithm points out the theoretical upper bound of the power control performance. In practice, the distributed algorithm by iteration is utilized. The joint control of power and rate in CDMA can be regarded as a game. All users in the game can obtain maximal utilities by adjusting their power and rate. The game ends at the Nash equilibrium.We first study the power control in CDMA cellular system. We introduce a new utility function, relative to traditional utility, the simulation results show that the new algorithm can attain higher utility using lower power.Due to the rapid development of multimedia services, we then use non-cooperative game (NG) theory to achieve joint control of power and rate in CDMA cellular system. The power and rate control problem is equivalent to be a non-cooperative game (NG) problem. What’s more, we introduce a cost function which is based on delay cost, prove the existence and uniqueness of the proposed algorithm’s NASH equilibrium (NE). The simulation results show that the algorithm can attain higher utility using lower power, also reduce the transmission delay of the user.At last, we study the joint power and rate control in CDMA cognitive radio networks. We also assume the problem between secondary users as a non-cooperative game, and one joint control of power and rate algorithm which is based on delay cost of secondary users is proposed, subject to the tolerable interference limits, prove the existence and uniqueness of the proposed algorithm’s NASH equilibrium. The simulation results show that the algorithm can attain higher utility and lower transmission delay using lower power. And sum interference made by the SUs cannot exceed interference threshold.