Proactive and Reactive DF Relaying for Cognitive Network with Multiple Primary Users

In this paper, the outage performance of a cognitive radio network with a pair of secondary transmitter and receiver is investigated in the presence multiple primary users over a number of licensed frequency band and multiple secondary relays (SRs). Two decode and forward (DF) schemes are considered for the relays, namely proactive and reactive DF schemes. An adaptive power allocation scheme for secondary transmitter and secondary relays is formulated under the joint constraints of the primary user outage and peak transmit power of the secondary users. Based on these strategies, analytical expressions for the outage probability of proactive and reactive DF schemes are derived. More precisely, our results demonstrate the impact of number of the active primary users (PUs) over a number of available licensed frequency bands on the outage performance of secondary network. Further, it is observed that the performance of the secondary network can be improved by extending the bandwidth of the primary users.