Abstract:

A two-phase cooperative transmission protocol based on best-relay selection for primary system is proposed in cognitive radio network, which consists of a primary transmitter-receiver pair and K secondary transmitter-receiver pairs. In the proposed protocol, with the transmission quality of service (QoS) constraints of secondary users, one of the secondary users coexisting in the same spectrum as the primary can be selected to serve as a decode-and-forward relay for primary system. The selection criterion is to maximize the ratio of signal to interference plus noise for the primary system. The outage performance of the primary system is analyzed. Simulation confirms that the efficiency of the proposed spectrum sharing protocol, i.e., the primary performance is improved. Meanwhile, the access opportunity for secondary users can be also guaranteed. In addition, it is indicated that the primary user can achieve better outage performance as K increases.

Key words: spectrum sharing, cooperative transmission, best-relay selection, outage probability