Modified Chirp Waveforms in Cognitive UWB System

In this paper we propose a method to modify chirp waveforms in cognitive ultra wideband (UWB) system. By utilizing the time-frequency relationship of the chirp waveform, we can avoid the spectrum authorized to other existing systems. After estimating other applications in the electromagnetic environment, the adaptive waveform generation is adopted which adapts to the changing wireless environment and synthesizes chirp waveform features in the time domain. Therefore, coexistence with other applications can be accomplished. Furthermore, the proposed scheme can avoid the frequency-time transform that can increase the system complexity. Computer simulations with additive white Gaussian noise successfully demonstrate an increase in performance with the proposed system as compared to traditional linear chirp systems for cognitive UWB systems.