On the reduction of power loss caused by imperfect spectrum sensing in OFDMA-based Cognitive Radio access

Cognitive Radio provides a promising solution for the spectrum scarcity in wireless systems. The main stage of a successful cognitive transmission is the spectrum sensing stage, where the spectrum is sensed to detect and avoid interfering with licensed users. Unfortunately, regardless of the type of the spectrum sensing technique employed, the probability of missed detection can still be relevant. This paper investigates the effects of missed detection probability on the energy resources of the cognitive system, and provides a new algorithm for power allocation in OFDM systems, which reduces the loss in energy resources, and guarantees the target Quality-of-Service (QoS) of the served users. Unlike the current algorithms, the proposed algorithm is based on the Sensing Side Information (SSI) and the Channel State Information (CSI) as well. Simulation results underline a relevant reduction in terms of power loss (with gains up to 50%) and a consequent improvement in QoS satisfaction.