A fast and reliable acquisition scheme for detecting ultra wide-band impulse radio signals in the presence of multi-path and multiple access interference

摘要

Ultra wide-band time-hopping impulse radio (UWB-TH-IR) creates a UWB signal by the continuous repetition of sub-ns wide bandwidth pulses which are pseudo randomly time hopped. A simple receiver, consisting of one or more one-shot correlators triggered at the precise moment the received pulse arrives at the receiver, can be used to detect the signal. This structure makes it necessary to initially synchronise to the incoming signals pseudo random time-hopping code. The combination of the low duty cycle waveform and the presence of a pseudo random time-hopping code can make the search space large, resulting in long synchronisation times. This paper proposes a so called quick search (QS) method which significantly reduces the search time by making more efficient use of the context of each observation. When compared to the exhaustive search (ES) method, the algorithm proposed here exhibits an acceptable degradation in detection performance and can reduce the search time by a factor equal to the code length. Performance is bench marked against the ES method along with the linear search (LS), random search (RS) and binary reverse search (BRS) thresholded algorithms.