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The Study And Improvement Of RAKE Receiver Algorithm For WCDMA System

Posted on:2007-01-03Degree:MasterType:Thesis
Country:ChinaCandidate:H Y LiFull Text:PDF
GTID:2178360182494011Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
WCDMA (Wide-band code division multiple access) system is one of schemes to realize the third generation mobile communication system. The physical layer of WCDMA system applies DS-CDMA (Direct Sequence Spread Code Division Multiple Access) technology and the system can select different spreading factors according to specific data rate. DS-CDMA system usually adopts RAKE receiver to effectively separate multi-path components, then to combine against multi-path fading. It is beneficial to enhance SNR (Signal Noise Ratio) of the system that the distinguishability of RAKE receiver should be properly increased in terms of WCDMA system's characteristics. Therefore, the reception effect can be improved. The path search and channel estimation, two parts of RAKE receiver can directly affect the performance of reception. Through analyzing the downlink channel of WCDMA system and other interference factors and researching the design of path search and channel estimation for downlink RAKE receiver of WCDMA system, this paper presented a new improved algorithm because of current algorithms with several limitation.Sometimes multi-path components only contain tiny signal energy. Hence RAKE receiver does not have to accept all multi-path components. RAKE receiver may mistakenly select the path merely with noise due to noise interference. Thus RAKE receiver must select multi-path components in terms of characteristics and complexities of channels. After analyzing and comparing some path search algorithms, the paper ultimately adopted a simple single threshold algorithm and attained optimal parameters through simulation.A channel estimation algorithm called weighted multi-slot averaging (WMSA) channel estimation algorithm not only can increase the time delay, but the performance also will be reduced when there is movement between the transmitter and receiver. A new adaptive WMSA channel estimation algorithm is presented in this paper. The simulation is carried out under MATLAB7.01. The result indicates theadaptive WMSA channel estimation algorithm showed in this paper possesses better performance in a wider range of application than traditional WMSA channel estimation algorithm does.
Keywords/Search Tags:WCDMA, RAKE receiver, path search, channel estimation, WMSA
PDF Full Text Request
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