Interference mitigation technique by sequence design in UWB cognitive radio

In this work, we propose an interference mitigation technique for ultrawide band (UWB)-impulse radio (IR) systems in the context of cognitive radio (CR). Such technique is based on the design of proper spreading sequences that introduce notch frequencies in both transmitted spectrum and matched filter (MF) receiver. In particular, binary, quaternary and polyphase direct sequence (DS) codes are proposed and specific optimization algorithms for sequence design adopted. The proposed technique shows the great potential of UWB systems in adapting the transmitted spectrum to counteract the narrowband (NB) interference from primary users (PUs) and, at the same time, guarantee low spectral emissions over PU communications.