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Improved Code Timing Estimator for DS-CDMA Systems Using Correlated Antennas in Time-Varying Fading Channels  

Kim Sang-Choon (동아대학교 전자공학과)
Jeong Bong-Sik (동아대학교 전자공학과)
Publication Information
Journal of the Korea Institute of Information and Communication Engineering / v.10, no.5, 2006 , pp. 910-920 More about this Journal
Abstract
We consider the problem of estimating a code-timing of DS-CDMA signal in antenna array systems in the presence of flat fading channels and near-far environments. We derive an approximate maximum likelihood algorithm of estimating the code-timing of a desired user for DS-CDMA systems to better utilize the time-varying characteristics of the fading process. In the development of code timing estimator, the given observation bits are divided into many sets of sub-windows with each sufficiently large. The proposed method uses sub-windows with equal size associated with the coherence time of channel fading. The alternative approach is that without the estimation of the fading rate, the sufficiently given observation bits are simply separated into two consecutive sets of sub-windows. The derivation of the proposed algorithms is based on multiple antennas partially correlated in space. The impacts of spatial fading correlation on acquisition and men acquisition time performance of the proposed algorithms are also examined.
Keywords
Code division multiple access; code timing estimation; maximum-likelihood estimation; synchronization; code acquisition; spatial fading correlation;
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