Single-Node And Cooperative Spectrum Sensing Based On Cyclostationarity

Spectrum resources shortage and the inefficient utilization of it caused by static allocation scheme has became the obstacle of further development in wireless communication. As a intelligent self-adaptive wireless system, cognitive radio can judge whether the licensed spectrum is occupied, it can also find spectrum hole and allocate it to cognitive users, thus solve the problem of inefficient utilization. As the prerequisite of spectrum allocation and power control, spectrum sensing plays a indispensable role in cognitive radio technology, on one hand it maximize the utilization of licensed spectrum, on the other hand it minimize the interference to primary user by monitoring the channle and order cognitive user to vacate ccupied channel in time.Single-node spectrum sensing is researched firstly in this paper, performance of energy detection is stimulated and studied. As it is showed in the result, energy detection lapsed in the circumstances of noise uncertainty caused by out-band interference thermal noise and imprecision of A/D conversion. Cyclic spectrum sensing based on the cyclostationarity of modulation signal has great advantage compared with energy detection, but it required massive calculation which become its drawback, in this paper, an algorithm combine these two methods together is presented, which can guarantee the validity through acceptable amount of calculation.Cooperative spectrum sensing is also studied in this paper, Multi-path effect, shadow effect and location uncertainty of mobile terminal caused by complex wireless environment can undermine the result of single-node spectrum sensing, while cooperate spectrum sensing can avoid these malfunctions. Optimization of decision fusion and data fusion which are two primary methods of cooperation have been discussed and analyzed in this paper. A method of multi-channel cooperation is presented in this paper, it has higher efficiency and higher tolerance to noise uncertainty as proved by the result of stimulation.