A proposal on spectrum sharing employing automatic cooperation-sharing protocol

To save the number of control messages in cooperation-spectrum sharing based paradigm, in this paper, we suggest the method using the negative acknowledge message (NACK) as command for cooperation and spectrum sharing. Here, primary transmission requires an optional transmission which is so-called sharing transmission phase whenever the mandatory phase is unsuccessful. In the sharing phase, the selected relay shares a power fraction of 1 - α for secondary transmitted signal while the remaining of α is for primary retransmitted signal. In the case of no relay collected, primary transmitter uses NACK as a command to retransmit the signal with fully power fraction (α = 1). In this scheme, we try to analyze frame error rate (FER) performance at primary destination. Theoretical and simulation results are provided to validate the analysis and confirm the efficiency of the protocol.