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      An application of independent component analysis to DS-CDMA detection

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      Yue_Fang_MSc.pdf (4.302Mb)
      Date
      2006-08-03
      Author
      Fang, Yue
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      This work presents the application of the theory and algorithms of Independent Component Analysis (ICA) to blind multiuser symbol estimation in downlink of Direct-Sequence Code Division Multiple Access (DS-CDMA) communication system. The main focus is on blind separation of convolved CDMA mixture and the improvement of the downlink symbol estimation. Term blind implies that the separation is performed based upon the observation only. Since the knowledge of system parameter is available only in the downlink environment, the blind multiuser detection algorithm is an attractive option in the downlink.Firstly, the basic principles of ICA are introduced. The objective function and optimization algorithm of ICA are discussed. A typical ICA method, one of the benchmark methods for ICA, FastICA, is considered in details. Another typical ICA algorithm, InfoMAX, is introduced as well, followed by numerical experiment to evaluate two ICA algorithms.Secondly, FastICA is proposed for blind multiuser symbol estimation as the statistical independence condition of the source signals is always met. The system model of simulation in downlink of DS-CDMA system is discussed and then an ICA based DS-CDMA downlink detector has been implemented with MATLAB. A comparison between the conventional Single User Detection (SUD) receiver and ICA detector has been made and the simulation results are analyzed as well. The results show that ICA detector is capable of blindly solving multiuser symbol estimation problem in downlink of DS-CDMA system.The convergence of ICA algorithm is, then, discussed to obtain more stable simulation results. A joint detector, which combines ICA and SUD and where ICA is considered as an additional element attached to SUD detector, has been implemented. It was demonstrated that the joint detector gives the lowest error probability compared to conventional SUD receiver and pure ICA detector with training sequences.
      Degree
      Master of Science (M.Sc.)
      Department
      Electrical Engineering
      Program
      Electrical Engineering
      Supervisor
      Takaya, Kunio
      Copyright Date
      August 2006
      URI
      http://hdl.handle.net/10388/etd-10272006-100225
      Subject
      DS-CDMA ICA
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      • Graduate Theses and Dissertations
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