Low Complexity Chirp Pulsed Ultra-Wideband System with Near-Optimum Multipath Performance

Abstract

This paper describes the Impulse Radio Ultra-Wideband (IR-UWB) system using linear chirp UWB pulses as symbols. The novel method of coherent or differentially coherent detection of chirp pulses in multipath channels is introduced. The method divides detection in the receiver between its analog and digital part; in the analog part of the receiver, received signal is compressed in frequency by mixing with locally generated chirp pulse and low-pass filtering. In this way, the time-bandwidth (TB) product of the resulting signal is reduced compared to the received signal and made approximately independent of duration of the transmitted signal. This results in relatively low complexity digital back-end of the receiver that is able to capture a large portion of the multipath energy, regardless of duration of the transmitted waveform. The work includes derivation of analytical properties of the system, including derivation of loss parameters that quantify system multipath performance. Numerical results include discussion on the system multipath loss performance with varying chirp duration. As well, a comparison is made with error performance of sampling receivers featuring the same computational complexity. Analysis of the robustness of the system's performance to different chirp pulse implementation errors is also provided.