Pulse or digital communications – Spread spectrum – Direct sequence
Reexamination Certificate
2001-02-07
2002-10-15
Ghayour, Mohammad H. (Department: 2634)
Pulse or digital communications
Spread spectrum
Direct sequence
C375S134000, C375S136000, C370S320000, C370S335000
Reexamination Certificate
active
06466611
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to communication systems, and more particularly to a detector for use in a receiver of multi-user communication system.
BACKGROUND OF THE INVENTION
Wireless communication systems have an ever-increasing use in transferring voice and data services. Such communication systems include the Code Division Multiple Access (CDMA) standard IS-95. The CDMA system is unique in that signals from several users overlap one another in one channel simultaneously. As a result, a receiver must process the combined signal from the one channel and extract the information sent to the user of interest. This process is known as multi-user detection or joint detection. Optimal multi-user detection schemes exist, but are computationally intensive.
Various sub-optimal receiver techniques have arisen to reduce the calculations necessary to extract the original user's signal while addressing the interference issue so as to limit error. These detection techniques include, among others, zero-forcing linear equalization, decision feedback equalization, and minimum mean-square-error equalization, used alone or in various combinations. Of these it has been reported by Klein et al. that minimum mean-square-error equalization provides the best performance in the paper “Zero-Forcing and Minimum Mean-Square-Error Equalization for Multiuser Detection in Code-Division Multiple-Access Channels”, IEEE Transactions on Vehicular Technology, Vol. 45, No. 2, pp. 276-287, May 1996, hereinafter referred to as MMSE-BLE (Minimum Mean Squares Error Block Linear Equalizer) useful in a CDMA system where the scrambling code is symbol-periodic.
The MMSE-BLE technique still requires extensive manipulation and calculation relating to the full system matrix defining the CDMA block transmission system channel, such as for the downlink of the proposed CDMA Third Generation Time Division Duplex (3G TDD) standard.
There is a need for improved multi-user detection in a CDMA communication system that further reduces computational complexity without sacrificing performance. It would also be of benefit to use existing hardware and to reduce processor resources.
REFERENCES:
patent: 5761237 (1998-06-01), Petersen et al.
patent: 5790537 (1998-08-01), Yoon et al.
patent: 5872776 (1999-02-01), Yang
patent: 5905721 (1999-05-01), Liu et al.
patent: 6088383 (2000-07-01), Suzuki et al.
patent: 1 065 799 (2001-01-01), None
patent: 1 128 564 (2001-08-01), None
Peter Hsin-Yu Wu et al., Multiuser detector with disjoint Kalman Channel Estimator for synchronous CDMA mobile radio channel' IEEE Transactions on Communications, vol. 48, No. 5, May 2000.*
Klein et al., “Zero-Forcing and Minimum Mean-Square-Error Equalization for Multiuser Detection in Code-Division Multiple-Access Channels”, IEEE Transactions on Vehicular Technology, vol. 45, No. 2, pp. 276-287, May 1996.
Bachu Raja S.
McCoy James W.
Ghayour Mohammad H.
Mancini Brian M.
Motorola Inc.
LandOfFree
Multi-user detection using a finite-impulse-response matrix... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-user detection using a finite-impulse-response matrix..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-user detection using a finite-impulse-response matrix... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2991228