On the compromise between delay and performance of the Three-Event Energy Detection algorithm in Cognitive Radio systems

Spectrum sensing is a crucial function required for an agile Cognitive Radio (CR) user. The simplest solution for CR spectrum sensing is provided by Energy Detection (ED) algorithms due to their independence on the Primary User (PU) signal's characteristics. Recently, we proposed an ED algorithm, which decides on the PU signal presence considering a sequence of three consecutive sensing slots, i.e., Three-Event ED (3EED). Even if the 3EED algorithm can operate without prior knowledge of the PU signal's characteristics, it operates best for low duty cycle values of PU, surpassing other known ED algorithms in terms of detection performance. However, it was shown that the 3EED algorithm introduces an additional detection delay of maximum one sensing slot. In this paper, we analyse the average detection delay for the 3EED algorithm and how this delay is related to the detection performance and the PU signal's duty cycle. Moreover, we propose and analyse a modified version of the 3EED algorithm that does not introduce an additional delay.