Coded-modulation Scheme for Interferences Mitigation from MB-OFDM Cognitive Radio and Its Performance Analysis

In order to satisfy the requirement of mitigating interferences caused by MB-OFDM cognitive radio systems, a type of coded-modulation scheme among two, four or several sub-carriers, is proposed, which is derived from side-lobe interference expressions. Based on this method, the side-lobe signal of MB-OFDM decreases quickly, and then the frequency notch, overlapping with other radio services, is deep enough. Consequently, interferences from cognitive radio systems is decreased, and the coexistence with other narrow band radio services is realized. In addition, theoretic analysis and simulation results show that the coded-modulation scheme has an additional merit: when SNR arrives at a certain value, compared with traditional modulation, much better Bit Error Rate (BER) performance can be achieved over Rayleigh fading channels.