Design And Simulation Of Power Control Based Interference Temperature Algorithms

For cellular mobile communication system, power control is one of the most essential elements. Power control is one of the most important approaches to effectively solve the near/far effect and the corner problems, to suppress system interference and to improve the communication quality. The aim of power control is to adjust the transmit power according to the fast changing mobile environment, making sure the power can keep the communication quality on a certain level and do not make too much interference to the other users.The interference temperature model was proposed by the FCC as a way to improve spectrum efficiency by dynamically managing and allocating spectrum resources. In cognitive radio system, it would allow unlicensed radios to transmit in licensed bands, provided their transmissions do not cause unnecessary interference to the licensed users. Licensed users previously define an interference temperature limit as a threshold. If the threshold is not violated, the permission is given to unlicensed users to coexist.For the interference limitation problems of unlicensed users in cellular mobile communication system, game theory based power control algorithms have been commonly used as a way to adjust the transmit power of the unlicensed users. But these algorithms jeopardize unlicensed user’s individual utility. Researches also show that the spectrum occupation ratio of licensed users is very low. In order to avoid these flaws, this thesis has designed SU-ITPC (System Utility based Interference Temperature Power Control) and SOR-ITPC (Spectrum Occupation Ration based Interference Temperature Power Control) algorithms. In order to minimize the block off ratio of unlicensed users, this thesis has also designed the UDIT (Uniform Distribution Interference Temperature) algorithm.For validating and evaluating the capability of the proposed algorithms, the proposed algorithms are simulated in MATLAB R2008a. Compared the SU-ITPC algorithm and the SOR-ITPC algorithm with traditional GTPC algorithm, both system utility and spectrum occupation ratio improve greatly. Simulation results also show that the UDIT algorithm effectively reduces the block off ratio of unlicensed users.