Study On MMSE-RAKE Receive Technology For Ultra-Wideband Communication System

As one of the most important parts of Ultra-wideband (UWB) system, UWB receiver is the key role for improving the performance. Due to the fine delay resolution of typical ultra wideband systems, RAKE receiver need to combine samples from a large number of multipath components in order to collect sufficient signal energy for reliable decisions. In addition, these samples need to be combined optimally in order to minimize bit error probability. The optimal linear minimum mean square error (MMSE) combining scheme might offer the best performance in the presence of multi-path channel and inter-symbol interference channel at the expense of high computational complexity.In addition, the MMSE solution requires inversion of covariance matrix, which can be quite computationally intense and may not even be possible in real-time for a high data rate system. Thus, it is desirable to find alternate solutions that approach, or exceed the performance of the MMSE receiver but require much fewer computations and can adapt rapidly. The multistage wiener filter(MWF) implemented by the correlation subtraction algorithm(CSA) is a pioneering breakthrough in deduced rank algorithms in that it meets or exceeds MMSE performance but does not require any matrix inversions nor computationally complex eigendecopmpositions.In this paper, the design of spectrum schemes, the shaping and producing of pulse signals, moudulation and power density are introduced firlsty. Simulation platform channel makes use of multi-path channel model provided by IEEE802.15.3a team, the abilities of RAKE receiver of UWB wireless communication in AWGN and multi-path channel are researched. Then we simulate and compare the performance of RAKE receiver with different reception schemes, combination mode and channel. The performance of single-user and multi-users in AWGN channel is also theoretically derived and simulated. The bit error rate(BER) expression of multi-users is given, and the capability of the UWB systems is analysised in the condition of multi-user. At last, we put forward a MMSE-RAKE receiver with low complexity, form using the efficient correlations subtractive architecture of the reduced rank multistage wiener filter(CSA-MWF). It is remonstrated that this receiver can achieve BER performance close to the MMSE receiver. The CSA generates an MMSE correlator without requiring matrix inversion, thereby reducing computational complexity; this facilitates direct replacement of the standard RAKE correlator.