Adaptive Interference Avoidance for Dynamic Wireless Systems: A Game Theoretic Approach

In this paper, we present an adaptive algorithm for interference avoidance, which can be applied in a distributed manner by active users in a CDMA wireless system to obtain optimal codewords and powers for specified target signal-to-interference plus noise ratio (SINR). The algorithm is derived using a game-theoretic approach in which separable cost functions with respect to codeword and power are defined, and joint codeword and power adaptation is formulated as a separable game with two corresponding subgames: the noncooperative codeword adaptation game, and the noncooperative power control game. Codeword and power adaptation use incremental updates in the direction of the best strategy, which are desirable in practical implementations since they allow the receiver to follow transmitter changes with corresponding incremental changes of the receiver filter and continue detection of transmitted symbols with high accuracy. The algorithm can also track variable target SINRs or variable number of active users in the system, and is therefore useful for dynamic wireless systems with varying quality of service (QoS) requirements. We illustrate the proposed algorithm with numerical examples obtained from simulations that show convergence and tracking properties of the algorithm for different scenarios