Cancellation Carrier Technique Using Genetic Algorithm for OFDM Sidelobe Suppression

In this paper, we investigate the sidelobe power reduction of non-contiguous orthogonal frequency division multiplexing (OFDM) signals using a genetic algorithm (CA) approach. OFDM is widely deployed in numerous wireless access networks since it can achieve high data rate while simultaneously being robust to the effects of multipath propagation. Despite these advantages, OFDM produces a substantial amount of out-of-band (OOB) interference that can potentially disrupt communications in adjacent wireless channels. A CA is a search technique that is employed to iteratively find the optimal solution given large solution spaces. To reduce the OOB emissions of an OFDM transmission, GAs can be employed to determine the amplitude and phase values of cancellation carriers (CCs), which are signals designed to cancel out the OOB emissions when added to this transmitted signal. Note that the CCs themselves do not carry any data, thus a delicate trade-off between overall data throughput and interference mitigation must be considered. However, with this CCs technique, there is a small loss in bit error rate which is caused by the fact that a certain amount of transmission power is wasted. Performance comparisons of the proposed CA technique with two other techniques presented in the open literature have been conducted.