Spectrum sensing in cognitive UWB impulse radio communication system

Abstract

This paper emphasizes on the issue of spectrum sensing or awareness in cognitive UWB impulse radio (CUWB). Three spectrum sensing schemes are proposed in this paper: The first scheme is based on frame-level block processing, while the second scheme aims at real time chip-level processing. Analytical results show that scheme 1 outperforms scheme 2 in terms of the probability of detection and false-alarm, nevertheless, high detection delay may render the applicability of scheme 1 in CUWB. Employing the low duty cycle characteristics of the UWB IR signal, we propose a chip-level based sequential processing and diversity detection scheme (scheme 3). Through extensive simulations, the results demonstrate that scheme 3 has the best receiver operating characteristic (ROC) curve that can attain the design goal of high probability of detection and low probability of false alarm. Both analytical and numerical results in terms of the “mean detection delay” and the “average false alarm run length” have also been presented in this paper. It is verified that by employing the diversity combining, scheme 3 outperforms scheme 1 in that it requires much less detection time for spectrum sensing.