In order to improve the probability of spectrum detection for Cognitive Radio (CR) and utilize the idle spectrum efficiently, a CR system based on cooperative detection and basic function modulation was proposed. Through the cooperation and adopting the energy detection with auto-adapted threshold, the CR system obtained the spectrum estimation and generated the sub-basis functions which were orthogonal with primary users'signals. The sub-basis functions were connected to be the system's basis function by convolution, and the system implemented receiving and transmitting through modulating the data on the system's basis function. Simulation showed that the system could improve the detection probability and debase the Bit Error Rate (BER). Its anti-interference and utilization of the idle spectrum were predominant.
