Spectrally efficient sensing protocol for cognitive relay systems

We propose sensing protocols for a cognitive dual-hop relay system where transmission from source (S) to destination (D) is accomplished over two phases with the assistance of a relay (R). A naive sensing protocol is to perform sensing at S and R before the respective transmission phase. This leads to substantial loss in spectral efficiency. We propose a sensing protocol where sensing is only performed at S when R is transmitting to D after canceling out the self-interference component that is known a priori. Theoretical analysis and numerical simulation validate that our proposed scheme achieves higher spectral efficiency than the naive sensing scheme while maintaining detection performance.