Log-likelihood ratio based signal sensing strategy for cognitive radios

Cognitive radios require spectrum sensing. IEEE 802.22 defines constraints on conceivable spectrum sensing techniques. In order to fulfill theses constraints on the required detection probability and allowed false alarm probability, the signal sensing requires a certain sensing time period and an appropriately adjusted decision threshold. This manuscript presents a novel dynamic spectrum sensing scheme which is based on soft outputs. The novel scheme allows the reduction of the sensing time in order to save calculation and power effort.