A Low Complexity Simulation Algorithm for TH-UWB MMSE RAKE Receiver

In this work, we implement a MMSE RAKE receiver for ultra-wideband (UWB) system using a new time-hopping system simulator. It is known that MMSE receiver has the best performance in terms of signal-to-noise-plus-interference-ratio (SINR) at the expense of high computational complexity. In addition, in order to process ultra-wideband signals, an extremely large sampling rate is mandatory. Therefore, in order to compute bit error rate (BER) curves, simulation time can be very long. Since the transmitted waveform is "hidden" in the transmitted-distorted-received waveform (TDR), as it will be shown in this work, a typical multiuser structure does not exist and the implementation of any multiuser detector in this algorithm might be a difficult issue. Therefore, applying this method, in this paper, a new approach of multiuser detection is achieved. With our approach, it is possible to reduce the simulation process significantly by avoiding any convolution operation, which is the most time-consuming. This algorithm takes advantage of some of the properties of time-hopping ultra-wideband (TH-UWB) systems in order to improve all the previous designs by several orders of magnitude, independently of the sampling rate, in terms of a very straightforward and fast processing. Relying on this approach, the number of simulation operations needed to evaluate MMSE receiver matrix are reduced. Thus, it is possible to process a large number of samples and to accurately estimate low BER in a short time application. Additionally, we derived a theoretical formula of the performance of the MMSE detector for PPM IR-TH-UWB based on this new approach. This formula might be valid for both, AWGN and multipath channel propagation. Simulations are provided in order to validate this approach