A Bandwidth-Efficient Transmission Scheme Based on Spectrum Sensing Results in CR Networks

A bandwidth-efficient transmission scheme based on conservative spectrum sensing results without a common reporting channel is proposed for cognitive radio (CR) networks. A secondary relay node can assist a secondary source node for both spectrum sensing and data transmission. The secondary source node determines when it needs to cooperate with the secondary relay node by checking the sensing results reported from the destination and relay nodes. The CR relay transmission mode is restricted to necessary condition when the directed link between the source node and destination node fails, which improves the bandwidth efficiency of secondary data transmission. Furthermore, spectrum sensing time is optimized to maximize the expected bandwidth efficiency under the constraints of spectrum sensing requirements. Numerical results verify the effectiveness of our scheme .