# Performance of Multistage Interference Cancellers in Space-Time Coded CDMA Systems

Alam, MM and Chockalingam, A (2003) Performance of Multistage Interference Cancellers in Space-Time Coded CDMA Systems. In: Conference on Convergent Technologies for Asia-Pacific Region TENCON 2003, 15-17 October, Bangalore,India, Vol.1, 137 -141.

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## Abstract

In this paper, we investigate the bit error performance of multistage interference cancellers in a K-user asynchronous/synchronous space-time coded CDMA system under near-far conditions. We consider orthogonal space-time block codes with $M, 1\leq{M}\leq8$ transmit antennas. We develop a generalized discrete time vector model for the received signal at the output of the matched filters, and use this model to evaluate the bit error performance of multistage interference cancellers (IC). Our performance results show that: (a) when accurate fade amplitude and timing estimates are available, the IC are less near-far resistant at low near-far ratios (NFR) compared to,that at high NFR, due to the unreliability of the interfering users' data estimates in the initial stages of the IC at low NFR; and (b) in the high NFR region, the near-far resistance is degraded due to inaccuracies in fade amplitude estimates. This indicates that that some amount of transmit power control is desired in IC to counter the loss of near-far resistance due to the above reasons.

Item Type: Conference Paper Ã�Â©1990 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. Space-time codes;CDMA;Interference cancellation Division of Electrical Sciences > Electrical Communication Engineering 29 Dec 2005 19 Sep 2010 04:22 http://eprints.iisc.ernet.in/id/eprint/4802