Cognitive radio-based interference avoidance schemes for MB-OFDM UWB

This paper focuses on the coexistence problem of multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems and current radio systems such as IEEE802.11a. Aiming at improving the performance of MB-OFDM UWB, we attempt to avoid interferences from IEEE802.11a systems. The cognitive radio (CR) technology is introduced to detect the distribution of co-channel interferences over all sub-bands. Then a CR-based frequency hopping (FH) scheme is proposed for MB-OFDM UWB systems to select sub-bands adaptively according to the interference pattern. Furthermore, for extreme scenarios where interferences are detected over all available sub-bands, a refined avoidance mechanism is enabled by turning off disturbed sub-carriers. Simulation results reveal that both the bit error rate (BER) performance and the throughput of the MB-OFDM UWB systems can be improved considerably by using the proposed schemes.