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A Blind Synchronous Multi-User DS-CDMA Equaliser With Partial Loading

A Blind Synchronous Multi-User DS-CDMA Equaliser With Partial Loading
A Blind Synchronous Multi-User DS-CDMA Equaliser With Partial Loading
In this paper, we propose a blind multiuser detection scheme in a direct sequence CDMA downlink scenario by means of a chip-level equaliser, which can be updated even if not all possible users are active, i.e. the system is partially loaded. The active synchronous users are separated by re-establishing orthogonality of their spreading sequences in a common chip-level equaliser. The adaptation algorithm is mainly based on a constant modulus (CM) criterion applied to the active users. The inactive codes in the system must be considered, for which we propose and compare three different methods: (i) a mean square error criterion for absent users, and a CM approach with (ii) zero modulus or (iii) the transmission of arbitrary signals with small code amplitude. For all three cases, stochastic gradient descent algorithms are derived. The proposed algorithms are analysed and compared through various simulations, which demonstrate the algorithms' convergence and BER performance.
0-7803-8380-X
803-806
Hadef, M
afe928bb-6ce4-4060-8370-593fd2402cd6
Weiss, S
a1716781-351d-41d2-8d67-3e3d34f16476
Hadef, M
afe928bb-6ce4-4060-8370-593fd2402cd6
Weiss, S
a1716781-351d-41d2-8d67-3e3d34f16476

Hadef, M and Weiss, S (2004) A Blind Synchronous Multi-User DS-CDMA Equaliser With Partial Loading. First International Symposium on Control, Communications and Signal Processing, Hammamet, Tunisia. 21 - 24 Mar 2004. pp. 803-806 .

Record type: Conference or Workshop Item (Paper)

Abstract

In this paper, we propose a blind multiuser detection scheme in a direct sequence CDMA downlink scenario by means of a chip-level equaliser, which can be updated even if not all possible users are active, i.e. the system is partially loaded. The active synchronous users are separated by re-establishing orthogonality of their spreading sequences in a common chip-level equaliser. The adaptation algorithm is mainly based on a constant modulus (CM) criterion applied to the active users. The inactive codes in the system must be considered, for which we propose and compare three different methods: (i) a mean square error criterion for absent users, and a CM approach with (ii) zero modulus or (iii) the transmission of arbitrary signals with small code amplitude. For all three cases, stochastic gradient descent algorithms are derived. The proposed algorithms are analysed and compared through various simulations, which demonstrate the algorithms' convergence and BER performance.

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More information

Published date: 2004
Additional Information: Event Dates: 21-24 March
Venue - Dates: First International Symposium on Control, Communications and Signal Processing, Hammamet, Tunisia, 2004-03-21 - 2004-03-24
Organisations: Electronics & Computer Science

Identifiers

Local EPrints ID: 259238
URI: http://eprints.soton.ac.uk/id/eprint/259238
ISBN: 0-7803-8380-X
PURE UUID: 081555f7-7c2c-46a8-95de-1c57a60c78f9

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Date deposited: 05 Apr 2004
Last modified: 06 Oct 2020 23:16

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