Wavelet packet-based transceiver for cognitive UWB

Abstract

Wideband spectrum in cognitive ultrawideband (UWB) is subjected to interference from licensed users although it consumes lower power. Wavelet packet transform is an alternative to Fourier transform with higher flexibility and spectrum utilization. In this paper, a wavelet packet-based transceiver is designed for cognitive UWB to improve robustness against interference from primary users. The proposed transceiver consists of two main components: 1) wavelet packet multicarrier modulation (WPMCM) for data transmission and 2) wavelet packet-based spectrum sensing (WPSS). In the transceiver, the presence of the primary user is sensed via WPSS with adaptive thresholding. Then, the WPMCM signal is transmitted over the detected unoccupied channels. The simulation results show interference reduction due to lower sidelobes level of power spectrum density compared with the Fourier-based system. Significant performance enhancement has been achieved in terms of probability of detection, probability of false alarm, and bit-error rate over UWB channels.