Interference robust self-mixing UWB systems using phase-domain spreading

We present a communication scheme aimed to improve robustness of impulse-UWB energy-detector receivers in the presence of narrowband interference. We first show that for this receivers, the matched filter waveform depends on interferer phase and amplitude, and it can become null for jammers with carrier frequency close to that of the desired channel. We then show that by multiplying the transmitted signal with an appropriately chosen, non-pseudo-random, unit-norm sequence, the baseband energy is maintained within 6 dB of the ideal (no interference) regardless of blockers. The proposed spreading technique enables energy-detection receivers to achieve high-interference robustness by using only simple baseband signal processing, and is hence well suited to low-power UWB systems.