Noncoherent Uwb Communication Technology Research

Ultra-wideband(UWB) wireless communication has emerged as a com-petitive technology for short range, low complexity wireless applications. UWB impulse radios convey information by transmitting ultra-short pulses repeatedly, which occupy large bandwidth and endow signals with fine res-olution. UWB receiver design under practical implementation constraints is super challenging. The traditional coherent UWB reciever, i.e., Rake receiver, have to sample and operate at least at the Nyquist rate, and needs to employ a large number of fingers to accurately estimate the dense multipath channel, and capture a considerable portion of the signal energy. To circumvent these draw-backs, receiver designs with lower complexity are needed to capture the energy of the UWB multipath channel with considerable cost, reasonable power con-sumption and low complexity. Therefore, a considerable part of the research interest have been shifted to sub-optimum, noncoherent systems. This research focuses on noncoherent UWB communication systems at the physical layer. In the thesis, several synchronization and demodulation algorithms for UWB signal have been proposed with low complexity and good performance.First, this thesis proposes a decode-and-forward (DF) two-way relay UWB network with a joint-demodulated non-coherent receiver to boost the system throughput. We consider a three nodes relay network with two terminals ex-changing information via a relay node during two time slots. After jointly detecting the simultaneously arrived signals, the relay node broadcasts the XORed signal to each terminal. For the transmitted signal, we design a CM TR based signal structure for two-way relay transmission. At the relay node, a novel non-coherent receiver is proposed to jointly estimate the XORed sig-nal. The receiver has simple structure with no delay line, which is available for realistic environment. In addition, the simple power allocation optimization is performed based on the result of the approximate effective signal to noise ratio (SNR). Simulation results show that the proposed technique achieves sig-nificant improvement over the existing nonrelay and relay schemes on system throughput.Then, we propose a low-complexity data-aided (DA) synchronization and efficient demodulation technique for 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 corre-lating the RDT straightforwardly, 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-redundance-included demodulation template (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 achieves a better bit-error-rate (BER) performance. Both the schemes can counteract the effects of inter-frame interference (IFI) and unknown multipath channels. Furthermore, analytical performance evaluations of the RDT-based receiver and the NRDT-based re-ceiver are provided. Simulations verify the realistic performance of the pro-posed receivers in the presence of multiuser interference and timing errors.