Asynchronous CDMA decorrelating detector

Details Asynchronous CDMA decorrelating detector Asynchronous CDMA decorrelating detector

1997-12-01

1999-06-29

Vu, Huy D.

Multiplex communications

Communication techniques for information carried in plural...

Combining or distributing information via code word channels

H04J 1300

Patent

active

059178299

ABSTRACT:
Method and apparatus for optimally decoding messages from CDMA signal sent by a plurality of users and received asynchronously at one receiver, using a minimal number of computations and minimal memory and processing resources. It is based on a novel approach to signal correlation, as well as to subsequent decoding by decorrelation, that requires a correlation period of only one symbol length, by providing for each user a pair of partial signatures sequences, with which the signal is correlated, deccorelating the results with the inverse of the cross-correlation matrix of all partial sequences, and combining the resultant partial symbol estimates--to obtain final estimated symbol values. The partial sequences are formed by separating each original sequence at a point corresponding to the estimated symbol boundary time, relative to an arbitrary correlation window, of one symbol length. The method can be modified to also apply to the case that any of the signals is received over multiple paths, any path possibly undergoing Doppler shift.

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