Performance Of Modified MAP Scheme For Cooperative Spectrum Sensing Over Fading Channels

Abstract: Cooperative spectrum sensing in cognitive radio is a robust strategy to combat fading and shadowing effects. However, large number of secondary users reporting to the fusion center for a final decision can cause significant delay. The local detectors transmit their log-likelihood ratio values in the descending order of their magnitudes. To obtain a quick and reliable decision, sequential detection is employed at the fusion center. Modified MAP scheme is proposed in which detection thresholds are calculated using maximum a posteriori (MAP) procedure with an imposed constraint on the number of sensors. Fading and shadowing effects on the reporting channels between the local detectors and the fusion center are explored. The performance of the proposed scheme is compared for the cases of perfect and fading reporting channels using simulation.

Keywords: Cognitive radio, cooperative spectrum sensing, sequential detection, cognitive control channels, fading and shadowing effects.