Distributed cooperative spectrum sensing strategy based on the joint use of network coding and transform-domain processing

In cognitive radio, spectrum sensing is used to find spectrum hole and identify the primary users. Cognitive users should continuously sense the spectrum and detect the presence of primary user as soon as possible. When cognitive user is far away from the primary user, the signal received from the primary user may be weak and difficult to be detected, causing the problem of low detection probability and long detection time. To solve such problems, this paper proposes a distributed cooperative spectrum sensing strategy based on the joint use of network coding and transform domain processing. Chirp signals with different parameters are used for cognitive users and conventional communication system is used for primary user. In the receiver end, fractional Fourier transform domain based signal processing method is used to separate cognitive users with different parameters and primary user. Network coding is used in different cognitive users to improve the spectrum efficiency of cognitive frequency bands. Theoretical analyses show that the proposed strategy can increase the detection probability, reduce detection time and improve the agility of the system at the same time.