The lending spectrum behavior of licensed users in cognitive radio is analyzed using game theory. Firstly, the system model of spectrum allocation is established. Secondly, based on the system model, two game theoretical algorithms are designed, which are Cournot game algorithm and Stackelberg game algorithm. Finally, simulation is done for the situation that the total quantity and the price of the rental spectrum vary with the increasing of the quantity of the primary users. The simulation results show that the two algorithms improve the spectrum utilization rate very much compared with the normal spectrum allocation algorithm. The two algorithms can...