Performance Evaluation of Power Control Algorithms in Cellular Radio Communication Systems

Abstract: Radio resources in wireless communication systems, implementing different multiple access techniques, must be wisely managed. This perspective is pivotal since the variations in propagation channel are very fast and the system is highly complex due to random and unpredictable movement of mobile users continuously. This complexity in the cellular system periodically contributes to different interference levels, high or low, resulting in the degradation of the system capacity. Transmitter power control is an efficient technique to mitigate the effect of interference under fading conditions, combat the Near-Far problem and conserve the battery life. Thus, an effective implementation of different power control algorithms in cellular radio communication systems can offer a significant improvement in the Quality of Service (QoS) to all the users. Choice of an appropriate power control algorithm is of prime importance, as it should aim at increasing the overall efficiency of the system. In this thesis different distributed power control algorithms, each suited for implementation under different cellular technologies, were studied extensively. Specifically, six distributed power control algorithms are compared through simulations on the basis of performance metrics like Carrier to Interference Ratio (CIR) and Outage for the downlink case. The work involves in finding the link gain matrix by modeling the cellular system in MATLAB and simulating different power control algorithms. The results obtained from the simulation work are used to evaluate the efficiency of the Distributed Power Control (DPC), Fully Distributed Power Control (FDPC), Improved Fully Distributed Power Control (FDPC+) and Balanced Distributed Power Control (BDPC) algorithms on the basis of convergence speed and at the same time evaluating the limitations of the different algorithms. Also, with the results obtained on the basis of outage comparison between Fixed Step Power Control (FSPC) and Augmented Constant Improvement Power Control (ACIPC) algorithms, the quality of active link protection and cell removal procedures are demonstrated.