Pre-FFT tapped delay line adaptive array for STBC-OFDM transmission in CR network

In this paper, a Pre-FFT tapped delay line adaptive array (TDLAA) for space-time block coded (STBC) orthogonal frequency division multiplexing transmission over underlay cognitive radio network is proposed to improve the performance of secondary users while opportunistically utilize pre-existing primary links without harmful interference. The technique is based on the transversal filter adaptive array which performs the joint interference cancellation and channel equalization. The Pre-FFT TDLAA maximizes transmission efficiency of SUs by incorporating the delayed signals to enhance the desired signal instead of excluding them as interferences. The optimum weight determination for the proposed scheme which performs joint processes under minimum mean square error criterion is developed. Simulation results demonstrate that the proposed scheme can suppress the interference effectively, thus improves the performance of STBC-OFDM transmission significantly.