Research On Receiver Techenologies For UWB Impulse Radio

Ultra-Wideband (UWB) impulse radio has attracted growing interest since it is capable of offering very high data rates by the transmission of ultrashort pulses. UWB transceivers are characterized by low cost and simple circuitry compared with the other narrowband transceivers. Interest in UWB is motivated by several features including: potential for very high data rates along with a commensurate increase in user capacity, promisingly small size and processing power, enhanced capability to penetrate through obstacles, and ultra-high precision ranging at the centimeter level. Although UWB impulse radio has many advantages, it faces a lot of challenges. The realization of receiver is a major difficulty because synchronization and demodulation are hard to carry out.In this paper, we develop a novel data-aided (DA) pulse-level synchronization algorithm for UWB impulse communication system. Pilot and information symbols are transmitted simultaneously by an orthogonal coed division multiplexing (OCDM) scheme, which obviously enhances the efficiency of system. In the receiver, an algorithm based on minimum average error probability (MAEP) of detector is applied to estimate the timing offset. The multipath interference (MI) problem for timing offset estimation is considered. The performances of our proposed scheme outperform that of algorithm based on maximum correlator output (MCO) in multipath channels, which is validated by the following simulations.After considering all the aspects of receiver for UWB impulse communication system, we propose a DA low-complexity synchronization and efficient demodulation scheme. Relying on judicious training symbols, the present algorithm can easily construct a redundance-included demodulation template (RDT) from the received signal. When the RDT is available, there are two approaches to select. One is to demodulate directly transmitted symbols by the RDT because the RDT involves information of timing offset in itself. Not requiring timing acquisition, and thereby this approach has considerably low complexity, which enhances the efficiency of system. The alternative is to first acquire the timing offset via simple energy detection which is used to amend the RDT to obtain a non-redundance-included demodulation template (NRDT) that removes the redundant noise, and then demodulate transmitted symbols with the aid of the NRDT. Obviously, the second approach has better performance and higher complexity in the receiver. Since the demodulation templates are constructed directly from the received signal, the two approaches do not need channel estimation and Rake receiver, which obviously decreases the complexity of system. Analytical performance evaluations and simulations of the two approaches are provided. The results demonstrate that the proposed algorithms are sound and efficient.