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Novel low-density signature for synchronous CDMA systems over AWGN channel

Hoshyar, R, Wathan, PP and Tafazolli, Rahim (2008) Novel low-density signature for synchronous CDMA systems over AWGN channel IEEE T SIGNAL PROCES, 56 (4). pp. 1616-1626.


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Novel low-density signature (LDS) structure is proposed for transmission and detection of symbol-synchronous communication over memoryless Gaussian channel. Given N as the processing gain, under this new arrangement, users' symbols are spread over N chips but virtually only d(v) < N chips that contain nonzero-values. The spread symbol is then so uniquely interleaved as the sampled, at chip rate, received signal contains the contribution from only d(c) < K number of users, where K denotes the total number of users in the system. Furthermore, a near-optimum chip-level iterative soft-in-soft-out (SISO) multiuser decoding (MUD), which is based on message passing algorithm (MPA) technique, is proposed to approximate optimum detection by efficiently exploiting the LDS structure. Given beta = K/N as the system loading, our simulation suggested that the proposed system alongside the proposed detection technique, in AWGN channel, can achieve an overall performance that is close to single-user performance, even when the system has 200% loading, i.e., when beta = 2. Its robustness against near-far effect and its performance behavior that is very similar to optimum detection are demonstrated in this paper. In addition, the complexity required for detection is now exponential to d(c) instead of K as in conventional code division multiple access (CDMA) structure employing optimum multiuser detector.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Electronic Engineering > Centre for Communication Systems Research
Authors :
Hoshyar, R
Wathan, PP
Date : April 2008
DOI : 10.1109/TSP.2007.909320
Copyright Disclaimer : © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Uncontrolled Keywords : chip-level iterative SISO MUD, Gaussian channel, low-density signature, message passing algorithm, overloaded condition, MULTIPLE-ACCESS CHANNELS, PARITY-CHECK CODES, MULTIUSER DETECTION, DS-CDMA, CAPACITY, SEQUENCES, FEEDBACK, PROBABILITY, ADAPTATION, ALGORITHM
Depositing User : Mr Adam Field
Date Deposited : 27 May 2010 14:44
Last Modified : 16 Jan 2019 16:23

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