Out-of-Band Interference Reduction Using Subcarrier Weighting and Cancellation Carriers

Orthogonal frequency division multiplexing (OFDM) systems suffer from large out-of-band (OOB) emissions. These OOB emissions are undesirable and may cause harmful interferences to adjacent channels (users). In this paper, we investigate the ability of combining two OOB emissions reduction techniques (the advanced subcarrier weighting (ASW) and the advanced cancellation carriers (ACC) techniques). The combination is proposed to provide significant OOB emissions reduction without degrading the performance of the communication system. Both techniques do not require performing complex optimizations or excessive computations which makes the combination suitable for practical systems. Simulation results show that significant OOB emissions reduction can be achieved using the proposed combination at the expense of slight BER degradation. Moreover, the combination results in negligible peak-to-average power ratio (PAPR) increase. The simplicity of the chosen techniques allows us to implement the combination in a software defined radio. Implementation results prove that the proposed combination can be introduced for real-time applications.