Sidelobe suppression for OFDM based cognitive radio systems

This paper investigates the sidelobe suppression techniques of orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) systems. We firstly argue that the existing sidelobe suppression algorithms cannot satisfy the special requirements of CR systems. Then we formulate the interference suppression problem of CR systems into two algorithms from capacity perspective, namely, average power allocation with cancellation subcarrier (CCs) scheme and adaptive subcarrier weighting scheme. We show that the capacity of the two schemes can well approximate the ideal waterfilling algorithm performance. We further show that under tough interference suppression requirement of licensed users (LU), the adaptive subcarrier weighting scheme is a better choice for CR systems.