Abstract: To oppose channel fading and improve spectrum utilization, a model of multi secondary users assist the primary users in a multichannels cognitive radio network was proposed. Based upon the maximal throughput principle, an allocate problem was created. Through theoretical analysis, the allocate problem was transformed into the standard assignment problem (AP), and a select algorithm basd on the Hungarian method was proposed. The simulation results show that the proposed relay mechanism can oppose the channel fading well and increase the throughput of the primary users significantly, thereby improve the spectrum utilization.

Key words: cooperative communication, cognitive radio networks, relay mechanism, resource allocation