A Power Control Algorithm Based On Game Theory In Cognitive Radio

From the earliest voice services to the latest4G high-speed multimedia services,the wireless communication has been rapidly developing. However, the spectrumresource, the foundation of wireless communication, is becoming increasingly preciousand scarce. National spectrum management systems assign the dedicated spectrum forradio, TV and other public service. It’s a pity that the licensed spectrum owned by thehost has no effective use. The idea of cognitive radio came into being. It allowscognitive users to access spectrum dynamically if they don’t affect the authorized users.The key technology of cognitive radio contains spectrum sensing, spectrummanagement, spectrum sharing and power control.The main study of this paper is cognitive radio power control. In system, user canachieves the ideal transmission quality by increasing the transmitting power; when otherusers perceived changes in the surrounding environment will dynamically change theirtransmitting power for improving the QoS. How to get optimal solution based onmutual checks and balances between them is the core content of this paper. The basicidea of game theory can effectively solve the decision-making issues of mutual restraint.So it is applied for cognitive radio power control algorithm.The content of this research contains: through theoretical study and simulationcomparison, several cognitive radio power control algorithms based on game theory areanalyzed. Aim at the advantages and disadvantages of these algorithms, we find thatthey have much room for improvement. In this paper, the NPG-NEW algorithm isdesigned for the following aspects: design modulation-independent utility function,design the non-linear cost function which has relationship with the link quality, anddesign the cost function which has relationship with SNR of user target. After that, weprove the NPG-NEW algorithm can not only reduce the transmitting power to improvethe overall effectiveness and fairness, but also ensure the communication quality of thefarthest user.The cognitive radio system allows unauthorized client access to licensed spectrum.But an important prerequisite is to ensure that does not affect normal communication ofauthorized client. Many recent studies did not consider the interference tolerance limitsof the authorized user. Therefore, NEW-IT based on considering the existence ofauthorized users is built. NEW-IT treats the authorized client as a gamer and adds it intothe whole game, which set up a special utility function with interfere tolerance. Forcomparison, the paper analyzes and simulates the NPG-ITLP based on the interferencetemperature model. We find that NEW-IT could more strictly control the total interference of the secondary user lower than interference threshold of the authorizeduser. At the same time, NEW-IT is superior to the NPG-ITLP on the performance oftransmit power, system utility and SINR of user.