Relay selection and power allocation for spectrum leasing in cooperative cognitive radio networks

Cognitive radio is a promising technology to relieve the pressure of spectrum crisis with the sharp increasement of wireless services. In this paper, the game model for spectrum leasing in cognitive radio network is considered, where the Primary Transmitter(PT) will choose some Secondary Transmitter(ST) as relay to resist multi-path fading and enhance the transmission efficiency. As a reward, the PT leases the authorized spectrum bands to the ST, which will use the authorized spectrum bands to communicate with the Secondary Receiver(SR). The PT attempts to get more help from STs, meanwhile, in order to enhance transmission capacity, each ST wants to get more access time for authorized spectrum bands. Therefore, game theory is employed to balance the profit between PT and ST. Different from previous works, we focus on the dynamic leasing time of the authorized spectrum, which is the key factor that affects the transmission efficiency both of PT and ST. By employing game theory, we derive the Nash bargaining solution: the optimal spectrum leasing time and allocated power of ST. Compared with traditional case that PT directly transmits data to Primary base(PB), the transmission efficiency of the PT in proposed model is improved significantly. Besides, the ST gets more transmission opportunities. Numerical results show that the proposed scheme is feasible and efficient.