RAKE-SOVA Equalization for Multi-Code CDMA System with Low Spreading Factor

Junhui ZHAO
Dongming WANG
Xiaohu YOU
Yun Hee KIM

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.5    pp.2087-2092
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.5.2087
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
RAKE,  SOVA,  multi-code CDMA,  low spreading factor,  

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In CDMA system, the RAKE receiver is commonly used to attain diversity gain by taking advantage of the good correlation properties of the spreading codes. However, at low spreading gains the good correlation properties of the spreading codes are lost and the RAKE receiver performance is severely degraded by intersymbol interference (ISI) due to the interpath interference (IPI). In case of multi-code CDMA system, there are exist multi-code interference (MCI). In order to suppress ISI and MCI, a novel receiver based on soft-output viterbi algorithm (SOVA) equalization is proposed in this paper. The SOVA equalization is applied to symbol sequences after RAKE combining and MCI cancellation to effectively eliminate the ISI during transmission of high rate data in wideband DS-CDMA systems. Simulation results show that the proposed RAKE-SOVA receiver significantly outperform the traditional RAKE and RAKE-VA receivers.