Cooperative spectrum sensing in cognitive networks

In cognitive networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. The difference of sensing performance between totally cooperative networks and partially cooperative networks (network cooperation gain) is studied in this paper. In a two user partially cooperative network, cognitive users U₁ and U₂ share their sensing results. While in a totally cooperative network, besides sharing sensing results, the cognitive user U₁ that receives less power from the primary user, also exploits the other cognitive user U₂ to act as its relay. We exploit a novel numerical model that considers some important factors neglected in the previous analysis, and exhibit some propositions and results on the following issues: what is the condition under which the network cooperation gain can be reached? What is the condition under which remarkable network cooperation gain can be achieved? What are the important factors that impact the gain greatly.