BER-optimized linear parallel interference cancellers for multicarrier DS-CDMA systems

Manohar, Shamaiah and Tikiya, Vibhor and Annavajala, Ramesh and Chockalingam, Ananthanarayanan (2005) BER-optimized linear parallel interference cancellers for multicarrier DS-CDMA systems. In: IEEE Global Telecommunications Conference (GLOBECOM 05), NOV 28-DEC 02, 2005, St Louis, MO.

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Abstract

In this paper, we consider the design and bit-error performance analysis of linear parallel interference cancellers (LPIC) for multicarrier (MC) direct-sequence code division multiple access (DS-CDMA) systems. We propose an LPIC scheme where we estimate and cancel the multiple access interference (MAT) based on the soft decision outputs on individual subcarriers, and the interference cancelled outputs on different subcarriers are combined to form the final decision statistic. We scale the MAI estimate on individual subcarriers by a weight before cancellation. In order to choose these weights optimally, we derive exact closed-form expressions for the bit-error rate (BER) at the output of different stages of the LPIC, which we minimize to obtain the optimum weights for the different stages. In addition, using an alternate approach involving the characteristic function of the decision variable, we derive BER expressions for the weighted LPIC scheme, matched filter (MF) detector, decorrelating detector, and minimum mean square error (MMSE) detector for the considered multicarrier DS-CDMA system. We show that the proposed BER-optimized weighted LPIC scheme performs better than the MF detector and the conventional LPIC scheme (where the weights are taken to be unity), and close to the decorrelating and MMSE detectors.

Item Type:	Conference Paper
Publisher:	IEEE
Additional Information:	Copyright 2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	28 Apr 2010 06:59
Last Modified:	19 Sep 2010 06:00
URI:	http://eprints.iisc.ac.in/id/eprint/27339

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