DMCA
Iterative (turbo) soft interference cancellation and decoding for coded CDMA (1999)
| Venue: | IEEE Trans. Commun |
| Citations: | 456 - 18 self |
BibTeX
@ARTICLE{Wang99iterative(turbo),
author = {Xiaodong Wang and H. Vincent Poor},
title = {Iterative (turbo) soft interference cancellation and decoding for coded CDMA},
journal = {IEEE Trans. Commun},
year = {1999},
volume = {47},
pages = {1046--1061}
}
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Abstract
Abstract — The presence of both multiple-access interference (MAI) and intersymbol interference (ISI) constitutes a major impediment to reliable communications in multipath code-division multiple-access (CDMA) channels. In this paper, an iterative receiver structure is proposed for decoding multiuser information data in a convolutionally coded asynchronous multipath DS-CDMA system. The receiver performs two successive softoutput decisions, achieved by a soft-input soft-output (SISO) multiuser detector and a bank of single-user SISO channel decoders, through an iterative process. At each iteration, extrinsic information is extracted from detection and decoding stages and is then used as a priori information in the next iteration, just as in Turbo decoding. Given the multipath CDMA channel model, a direct implementation of a sliding-window SISO multiuser detector has a prohibitive computational complexity. A low-complexity SISO multiuser detector is developed based on a novel nonlinear interference suppression technique, which makes use of both soft interference cancellation and instantaneous linear minimum mean-square error filtering. The properties of such a nonlinear interference suppressor are examined, and an efficient recursive implementation is derived. Simulation results demonstrate that the proposed low-complexity iterative receiver structure for interference suppression and decoding offers significant performance gain over the traditional noniterative receiver structure. Moreover, at high signal-to-noise ratio, the detrimental effects of MAI and ISI in the channel can almost be completely overcome by iterative processing, and single-user performance can be approached. Index Terms — Coded CDMA, instantaneous MMSE filtering, multiuser detection, soft interference cancellation, Turbo processing.
Keyphrases
soft interference cancellation extrinsic information detrimental effect interference suppression single-user siso channel decoder low-complexity siso multiuser detector next iteration major impediment multiuser information data priori information iterative processing intersymbol interference single-user performance multipath code-division multiple-access turbo decoding sliding-window siso multiuser detector soft-input soft-output multiuser detector multipath cdma channel model turbo processing index term reliable communication nonlinear interference suppressor multiple-access interference prohibitive computational complexity asynchronous multipath ds-cdma system decoding stage successive softoutput decision instantaneous mmse filtering novel nonlinear interference suppression technique high signal-to-noise ratio offer significant performance gain simulation result iterative process efficient recursive implementation direct implementation iterative receiver structure low-complexity iterative receiver structure traditional noniterative receiver structure
