Low complexity iterative interference estimation and decoding for OFDM-based cognitive radio systems

Coexistence of different users in cognitive radio (CR) network sharing the same frequency band can cause severe in-band interference. In this paper, we propose a novel scheme of joint interference estimation and decoding to combat the narrowband interference for OFDM-based (orthogonal frequency division multiplexing) CR systems in an iterative way. Moreover, we present some complexity reduction techniques including frequency domain partial averaging which only requires the knowledge of the number of interfered subcarriers. By exploiting the results of decoding, the proposed scheme can achieve an accurate estimation of noise plus interference variance, and a quasi-optimal bit error ratio (BER) performance. It is also robust against the variation of interference power and bandwidth, and the positive error of the knowledge of the number of interfered subcarriers.