Research On Spectrum Sensing Based On GNU Radio And USRP

In recent years, with the rapid development of wireless communication technology, spectrum resource cannot meet the growing wireless communication service and users? requirements. However, spectrum resources are not completely utilized because of the static and fixed allocation policy. Cognitive radio is deemed to an efficient way for solving the situation of spectrum emergency. As one of the key techniques of cognitive radio, spectrum sensing can detect spectral hole for communication, which can effectively improve the utilization of spectrum.The research efforts on spectrum sensing are increasing, but most of them are based on theory and simulation, which is lack of verify from practical platform. A platform based on GNU Radio and USRP is designed to test and verify spectrum sensing algorithms, which improves the performance of spectrum sensing.Firstly, a cooperative spectrum sensing algorithm based on double threshold and optimal decision threshold energy detection is proposed and verified. Using the influence of noise uncertainty, cooperative spectrum sensing can effectively improve the performance of sensing. Results obtained from all users are combined by maximal ratio combining to make full use of all cognitive users? channel gain in fusion center. The optimal decision threshold for soft-decision cooperative spectrum sensing, which is based on the minimum total error probability criterion, is regarded as the final decision threshold. Simulations demonstrate that performance of sensing has been actually improved.Secondly, multiband cooperative spectrum sensing algorithm is proposed and verified. The entire frequency band is divided into several subbands by each cognitive user. The result formed by the fusion of results obtained from double threshold detection in each subband, is sent to fusion center as local consequence. The final decision is made. Two fusion methods are presented when cognitive user merged local results: merge all local results and merge part local results. The realization of spectrum sensing technology, transmission theory and judgment based on GNU Radio and USRP identifies the superiority of multiband cooperative spectrum sensing algorithm.By the actual spectrum sensing environment based on GNU Radio and USRP, the paper tests the foregoing double-threshold cooperative spectrum sensing algorithm as well as multiband cooperative spectrum sensing algorithm and realizes the function of spectrum detection, which is of great significance on the practical application of spectrum sensing.