Design and Performance Analysis of the Receivers for DS-UWB Communication Systems

The main feature of ultra wideband (UWB) communication systems is the high resolution of multipath arrivals, which is due to its large transmission bandwidth. Thus, the received signal has many replicas of the transmitted signal, and serious inter-symbol interference (ISI) effects can be made. For direct-sequence ultra wideband (DS-UWB) systems, RAKE receiver despreads the received signal in each finger and combines the despreaded outputs to achieve the multipath diversity of the desired signal. However, for practice issue, the fingers of RAKE receiver should much less than the number of multipaths. RAKE necessarily optimal. To deal with this problem in such a dense multipath environment, the coefficients of RAKE should be redesigned to maximizing signal energy and suppressing ISI. We design and analysis several of receivers based on the RAKE structure, a chip-based equalizer and a novel RAKE/DFE scheme which place a decision-feedback equalizer (DFE) in back of the RAKE receiver to more efficiently cancel the severe ISI. This RAKE/DFE scheme reveals remarkable advantage when low complexity receiver is implemented. Unlike the previous works on with DFE, not just the same as the channel coefficients. Adaptive the RAKE/DFE. The analytical error probability is derived. From simulations, we conclude that the developed RAKE/DFE scheme can suppress can suppress the ISI efficiently