Interference cancellation for OFDM systems in presence of overlapped narrow band transmission system

Narrowband interference (NBI) is one of the most important problems in an OFDM system, which not only degrades the signal performance on the overlapped subcarriers, but also affects the signal performance on the nearby subchannels due to the spectral leakage effect of DFT demodulation at the receiver. In this paper, we consider the NBI problem caused by narrow band digital communication systems, and propose a novel NBI cancellation method. We consider the NBI reconstruction problem including NBI central frequency and its bandwidth estimation. Simulation results show that this method can achieve about 6 dB signal to interference plus noise ratio (SINR) gain if the interference bandwidth is about twice of that OFDM bins and the system SINR is about 0 dB. As the bandwidth of NBI decreases, more SINR gain will be obtained. Meanwhile, we also consider the system implementation problem, it has shown that its implementation complexity is not high based on the current digital signal processing techniques. If zoom FFT is employed in our system, the calculation complexity can he reduced considerably.