Exploiting the Multi-Path Diversity and Multi-User Cooperation to Detect OFDM Signals for Cognitive Radio in Low SNR with Noise Uncertainty

Sensing the weak signals of primary users by cognitive devices greatly challenges the capability of energy detector under noise uncertainty. This paper proposes three schemes for detecting the primary signals of OFDM type. They are based on the auto-correlation ratio detection and exploit the multi-path diversity gain and multi-user cooperation. The detection and false alarm probabilities are then calculated and analyzed. The simulation results show that They effectively improve the performance of the ratio detection.