Sensing and communication protocols in cognitive sensor relay networks

We present sensing and communication protocols for a dual-hop sensor relay network operating on secondary basis in licensed spectrum. We consider a two-phase communication protocol: in the first phase, the source node transmits to the relay and in the second phase, the relay node transmits to the destination node. A naive sensing protocol is to perform sensing in slots that are scheduled prior to transmission in each phase. This leads to substantial loss in throughput and also can be an issue for delay-sensitive applications. To address this, we propose a sensing protocol wherein sensing is performed at the source node during the second transmission phase. Using a simple reward model, we show that the proposed protocol outperforms the naive protocol while providing better detection performance.