Noncoherent ultra-wideband radios

Ultra-wideband (UWB) radios have received increasing attention recently for their potential LPD attributes and low-power consumption and low-complexity implementation. Because of the pulsed or duty-cycled nature of the ultra-short transmitted waveforms, timing synchronization and channel estimation pose major, and often conflicting, challenges. In order to address (or in fact bypass) both tasks, we design and test noncoherent UWB (de)modulation schemes, which remain operational even without timing and channel information. Relying on integrate-and-dump operations of what we term "dirty templates", we first derive a maximum likelihood (ML) optimal scheme. We further establish a conditional ML demodulator with lower complexity. Analysis and simulations show that it can also be applied after (possibly imperfect) timing acquisition, as well as be adapted to a transmitted reference (TR) scheme. The resultant robust-to-timing (RT)TR considerably improves performance of the original TR in the presence of timing offsets or residual timing acquisition errors.