Channel estimation algorithms for cooperative spectrum sensing in amplify-and-forward cooperative system

In amplify-and-forward (AF)-based cooperative spectrum sensing system, the bit-error-rate (BER) performance and detection probability will decrease because of the existence of channel estimation error. In this paper, the influence of channel estimation error on system performance is firstly deduced, and then, linear minimum mean-square error (LMMSE) channel estimation algorithm with filtering delay time-domain windowing (LMMSE-filtering-DTW) technique and modified singular value decomposition-based LMMSE algorithm are proposed to improve the channel estimation performance for code division multiple access system and orthogonal frequency division multiplexing system in AF cooperative scenario, respectively. Simulation results verify the effectiveness of the two proposed channel estimation algorithms in cooperative spectrum sensing, and when E_b/ N₀ is bigger than 20dB, given the required false alarm probability smaller than 15%, the difference of detection probability between the channel obtained using the proposed channel estimation algorithms and the ideal channel is less than 2.5%, respectively.