Robust Ultra-Wideband Signal Acquisition

Ultra-wideband (UWB) communication is envisaged to be deployed in indoor environments, where the noise distribution is decidedly non-Gaussian. A critical challenge for impulse radio UWB is the synchronization of nanosecond-long pulses. In this paper, we propose two acquisition schemes which are robust to uncertainties in the noise distribution and which operate directly on samples taken at symbol-rate. The only channel state information that the algorithms need can be obtained by estimation of an aggregate channel gain, avoiding channel-related complications. Following Huber's M-estimates for the Gaussian mixture noise model, the proposed robust acquisition systems outperform their traditional counterparts designed according to the Gaussian noise assumption. Necessary modifications for operation under multiple access interference are also introduced. Theoretical and simulation-based performance evaluations that reflect the asymptotic variance, normalized mean-square error and the bit error rates demonstrate the gains offered by the robust procedures.