Further Enhancement for Active Interference Cancellation on MB-OFDM UWB Transmission

When an ultrawideband (UWB) transmitter is operating, it must not cause interference to existing primary users. Three new techniques are proposed in this paper in order to enhance the active interference cancellation (AIC), which is a technique to avoid causing the interference, for multiband-OFDM UWB transmitters. The first technique applies cyclic shifting while the second technique applies phase shifting to the frequency-domain data symbols. The third technique is a combination of these two techniques and is shown to improve the performance by about three orders of magnitudes. It is shown by simulation that the proposed techniques are able to enhance the performance of AIC significantly albeit higher complexity and a need for sending feed-forward bits.