Code tracking of DS-CDMA systems in the presence of multiuser interference and additive noise

The code tracking performance of a noncoherent digital delay-locked loop for DS-CDMA systems is investigated in the presence of multiuser interference and additive noise. Following the description of the code tracking loop, the tracking discriminator characteristics are theoretically analyzed. A detailed theoretical analysis of the steady-state probability density function (PDF) and variance of the tracking jitter is performed by solving the first-order Fokker-Planck equation, and the mean loss-of-lock time of the loop is derived. Numerical evaluation of the PDF is done and compared to the Gaussian distribution. Numerical results of the variance of the tracking jitter and the mean time to lose lock are also presented to illustrate the tracking performance for Gold code sequences. Optimal performance is evaluated minimizing the variance of the tracking jitter, by proper selection of the loop offset.

[1]  K. Kallman,et al.  Jitter performance of a baseband sampled code tracking loop , 1994, IEEE Trans. Commun..

[2]  Ryuji Kohno,et al.  New concepts and technologies for achieving highly reliable and high-capacity multimedia wireless communications systems , 1997 .

[3]  Giovanni Emanuele Corazza.  On the MAX/TC criterion for code acquisition and its application to DS-SSMA systems , 1996, IEEE Trans. Commun..

[4]  Marvin K. Simon,et al.  Optimum Performance of Suppressed Carrier Receivers with Costas Loop Tracking , 1977, IEEE Trans. Commun..

[5]  M. Pursley,et al.  Performance Evaluation for Phase-Coded Spread-Spectrum Multiple-Access Communication - Part I: System Analysis , 1977, IEEE Transactions on Communications.

[6]  Someshwar C. Gupta,et al.  Direct-sequence spread-spectrum parallel acquisition in a fading mobile channel , 1990, IEEE Trans. Commun..

[7]  Andreas Polydoros,et al.  A Unified Approach to Serial Search Spread-Spectrum Code Acquisition - Part I: General Theory , 1984, IEEE Transactions on Communications.

[8]  Riccardo De Gaudenzi,et al.  Decision-directed coherent delay-lock tracking loop for DS-spread-spectrum signals , 1991, IEEE Trans. Commun..

[9]  Marvin K. Simon.  Noncoherent Pseudonoise Code Tracking Performance of Spread Spectrum Receivers , 1977, IEEE Trans. Commun..

[10]  M. Pursley,et al.  Analysis of Direct-Sequence Spread-Spectrum Multiple-Access Communication Over Rician Fading Channels , 1979, IEEE Trans. Commun..

[11]  ANDREAS POLYDOROS,et al.  Analysis and Optimization of Correlative Code-Tracking Loops in Spread Spectrum Systems , 1982, MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications.

[12]  Jack Kenneth Holmes,et al.  Coherent Spread Spectrum Systems , 1982 .

[13]  M.B. Pursley,et al.  Crosscorrelation properties of pseudorandom and related sequences , 1980, Proceedings of the IEEE.

[14]  J. J. Spilker.  Delay-Lock Tracking of Binary Signals , 1963, IEEE Transactions on Space Electronics and Telemetry.

[15]  Andreas Polydoros,et al.  A Unified Approach to Serial Search Spread-Spectrum Code Acquisition - Part II: A Matched-Filter Receiver , 1984, IEEE Transactions on Communications.