Convolutional interleaver used for OFDM-based cognitive radio systems in severely fading channel

Orthogonal frequency division multiplexing (OFDM) based cognitive system is a mature technique in cognitive radio (CR). In terms of the problem that the performance of OFDM-based CR system degrades due to the consecutive errors in severely fading, we propose that the convolutional interleaver is applied after the forward error correction (FEC) to solve the problem. In addition, the capacity of register and the processing delay are reduced half compared with using the block interleaver. Simulation results showing the effectiveness and flexibility are presented.