Cyclic-mean based synchronization and efficient demodulation for UWB ad hoc access: Generalizations and comparisons

Synchronization is a performance-critical factor in all communication systems, but becomes particularly challenging in ultra-wideband (UWB) radios due to the ultra-short length of the transmitted pulses. Presence of severe inter-symbol interference (ISI) and multi-user interference (MUI) render the synchronization task even more difficult. The present paper deals with a blind synchronization and demodulation scheme which relies on intermittent transmission of nonzero mean symbols. This transmission pattern enables MUI- and ISI-resilient timing acquisition via energy detection and low-complexity demodulation by correlating the received waveform with a synchronized aggregate template (SAT). The resultant SAT receiver offers distinct advantages over the traditional RAKE and has remarkably low-complexity. Its blind operation nicely fits the requirements of multi-user ad hoc access and its ability to handle ISI is particularly attractive for UWB communications. Analytical performance evaluation of the novel timing estimator and the SAT demodulator is provided along with comparisons with the RAKE receiver for a single user link without ISI. Simulations confirm the analytical results and corroborate the high potential SAT-based UWB modems have for deployment.