Training-Based Synchronization and Demodulation With Low Complexity for UWB Signals

In this paper, we propose a low-complexity data-aided (DA) synchronization and efficient demodulation technique for an ultrawideband (UWB) impulse radio system. Depending on the autocorrelation property of a judiciously chosen training sequence, a redundance-included demodulation template (RDT) can be extracted from the received signal by separating, shifting, and realigning two connected portions in the observation window. After constructing the RDT, two receiver designs are available. One approach is to demodulate transmitted symbols by correlating the RDT in a straightforward manner, which does not require the explicit timing acquisition and, thus, considerably reduces the complexity of the receiver. An alternative approach is accomplished with the assistance of a non-RDT (NRDT). The NRDT-based receiver is able to remove the redundant noisy component of the RDT by acquiring timing offset via a simple synchronization scheme, therefore achieving a better bit error rate (BER) performance. Both the schemes can counteract the effects of interframe interference (IFI) and unknown multipath channels. Furthermore, analytical performance evaluations of the RDT- and NRDT-based receivers are provided. Simulations verify the realistic performance of the proposed receivers in the presence of multiuser interference (MUI) and timing errors.