Doubly Sequential Energy Detection for Distributed Dynamic Spectrum Access

We study the distributed sequential energy detection problem in the context of spectrum sensing for cognitive radio networks. We formulate a novel Doubly Sequential Energy Detector (DSED) and provide a comprehensive study of its performance. Specifically, we present the first method that sequentially combines the decisions of the Cognitive Radio nodes wherein each node is running an independent Sequential Energy Detector (SED). Through extensive simulations it is demonstrated that (i)our novel sequential version of the energy detector delivers a significant throughput improvement of 2 to 6 times over the fixed sample size test while maintaining equivalent operating characteristics as measured by the Probabilities of Detection (PD) and False Alarm (PFA), and (ii) the Doubly Sequential Procedure at the Base Station further boosts the SED performance while improving the robustness for shadowed Cognitive Radio nodes. For example, for a PD > 0.95, our simulations demonstrate that the DSED has a PFA <; 0.20 while utilizing upto 8 times fewer samples than the equivalent energy detector upto a Signal to Noise Ratio of -10 dB, below which its performance gracefully degrades.