tailieunhanh - Báo cáo: Iterative Successive Interference Cancellation for Quasi-Synchronous Block Spread CDMA Based on the Orders of the Times of Arrival

Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2011, Article ID 918046, 12 pages doi: Research Article Iterative Successive Interference Cancellation for Quasi-Synchronous Block Spread CDMA Based on the Orders of the Times of Arrival Yue Wang,1 Mohammud Z. Bocus,2 and Justin P. Coon1 1 Telecommunication 2 Centre Research Laboratory (TRL), Toshiba Research Europe Limited, 32 Queen Square, Bristol BS1 4ND, UK for Communication Research, University of Bristol, Bristol BS8 1TW, UK Correspondence should be addressed to Yue Wang, Received 31 March 2010; Revised 28 September 2010; Accepted 30 November 2010 Academic Editor: Hikmet Sari Copyright © 2011 Yue Wang et. | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2011 Article ID 918046 12 pages doi 2011 918046 Research Article Iterative Successive Interference Cancellation for Quasi-Synchronous Block Spread CDMA Based on the Orders of the Times of Arrival Yue Wang 1 Mohammud Z. Bocus 2 and Justin P. Coon1 1 Telecommunication Research Laboratory TRL Toshiba Research Europe Limited 32 Queen Square Bristol BS1 4ND UK 2 Centre for Communication Research University of Bristol Bristol BS8 1TW UK Correspondence should be addressed to Yue Wang Received 31 March 2010 Revised 28 September 2010 Accepted 30 November 2010 Academic Editor Hikmet Sari Copyright 2011 Yue Wang et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Recently a block spreading code division multiple access BS-CDMA technique was presented whereby user-specific precoding along with orthogonal spreading codes is used to achieve multiuser interference- MUI- free reception when all users arrive at the base station simultaneously. In practice however imperfect synchronization destroys the orthogonality among users and MUI occurs. To mitigate the MUI in BS-CDMA due to quasisynchronous reception this paper proposes an iterative successive interference cancellation SIC receiver where cancellation of interfering signals is ordered according to the times of arrival TOA of the signals from different users. The ordering criterion is justified through analysis and simulation on the average signal-to-interference-plus-noise ratio SINR of different users where it is shown that in a quasisynchronous BS-CDMA system ordering with regard to increasing TOA is equivalent to ordering with respect to decreasing average SINR when practical channels such as the exponentially decaying channel is considered.