A novel decoding technique for least-squares notching precoder in OFDM cognitive radio

Abstract

OFDM has been recognized as a suitable candidate for cognitive radio systems. However, the high out-of-band leakage in OFDM systems has the tendency to interference with primary users operating in adjacent bands. In order to protect neighboring systems, sidelobe leakage needs to be restricted below the prescribed mask. There are various well-known techniques in the literature for sidelobe suppression. In particular, the least-squares notching precoder (LSNP) based on projection matrix is computationally very effective and has good sidelobe suppression. However, it invariably introduces distortion on each subcarrier thereby degrading the system's error-rate performance. Existing solutions for enhancing error performance are either computationally expensive or degrade throughput of the system. In this paper, we proposed a novel decoding technique which significantly improves error-rate performance without affecting the throughput of the system. In addition to that, the proposed scheme when joined with the existing iterative recovery algorithm further improves the performance and requires as few as one iteration to achieve minimum bit-error-rate. © 2016 IEEE.