Research On The Spectrum Sharing For Cognitive Radios Based On Game Theory

Cognitive Radio (CR) is a new technology to improve utilization of spectrum resource of wireless communication. It provides an effective way to solve the conflict between the low effectiveness of the static spectrum management and the growing demands of spectrum resource. In the wireless network, spectrum competition between users is considered as a game. The wireless network resources sharing and distribution could establish a game model. Game theory is one of the most commonly methods of studying cognitive radio.It is divides into two models: the first model is multi-primary service and only one secondary service spectrum sharing mode. According to the insufficient utility function of the original secondary system model, an improved utility function of the secondary service is proposed by introducing a more effective reinforced factor based on spectrum occupancy of the secondary service. The simulation results show that the more spectrum occupancy of the secondary service, the more profit of primary system. When the channel quality becomes poor, price of shared spectrum for the primary service does not reduce with high spectrum occupancy of the secondary service. This ensures that the primary system can obtain its reasonable profit, improving spectrum resources shortage.The second model studies a spectrum sharing model of multi-primary service and multi-secondary service. By introducing a new utility function to quantify satisfaction of primary system and secondary system, analysis the change of size and price of primary system when number of secondary users changes. The simulation results show that along with the increase of the total number of secondary users, the size of shared spectrum for the primary service increases and price is almost the same, making the secondary system reduce the price of renting spectrum.