Analysis of Performance Degradation due to Channel Estimation Error in Pre-Rake TDD/CDMA

Norharyati BINTI HARUM
Yuh TAMURA
Sigit P.W. JAROT
Riaz ESMAILZADEH
Masao NAKAGAWA

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B    No.6    pp.2508-2515
Publication Date: 2005/06/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.6.2508
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
Rake,  Pre-Rake,  channel estimation,  TDD-CDMA,  

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Summary: 
In recent years, Pre-Rake combining technique has become a hot topic of research as it decreases the complexity of the portable mobile unit, while achieving the same multipath diversity effect of the Rake receiver. The technique is based on precoding of the transmitted signal relying on knowledge of the channel estimation response before transmission. This a priori channel state information is available in Time Division Duplexing (TDD) systems, since the same channel is used both in uplink and downlink. In practice, the error in channel estimation in Pre-Rake system occurs due to time variability in mobile radio channel. Most previous works on Pre-Rake in TDD CDMA have not taken into consideration the effect of imperfect channel estimation. In this paper, we present Pre-Rake performance under imperfect channel estimation due to time variability in TDD system, depending on Doppler Frequency and compare it with the ideal Pre-Rake system. Numerical analysis and computer simulations were carried out to obtain the system error probability.