Communication method, receiver and base station

Abstract

A multi-user receiver which uses at least two antenna elements and in which the influence of interference is reduced, the receiver comprises: means (200) for pre-filtering a wideband antenna signal, the pre-filtering means being determined on the basis of a spatial covariance matrix estimate, which spatial covariance matrix estimate is obtained from wideband antenna signals by sampling, arranging sampled values into a signal vector and by multiplying the signal vector by its conjugate transpose vector, means (210, 218) for removing the whitening from signals of predetermined users by using an inverse matrix of the matrix used in the whitening filter, means (202, 204, 206, 208, 210) for performing multi-path combining and multi-antenna combining.

Description

REFERENCE TO RELATED APPLICATIONS [0001] This is a divisional application of application Ser. No. 10 / 760,532, filed Jan. 21, 2004, which claims the benefit of Patent Application No. 20031609, filed Nov. 6, 2003 in Finland. The disclosure of the prior applications is hereby incorporated by reference herein in its entiretyFIELD [0002] The invention relates to a method for reducing the influence of interference in a multi-user receiver, when the multi-user receiver receives signals from users having different data rates using at least two antenna elements. The invention also relates to a multi-user receiver and a base station. BACKGROUND [0003] Several combining techniques have usually been used to combine diversity antennas or different antenna branches in antenna arrays to create nulls towards interfering signals while maintaining a large antenna gain towards the desired signal, thus reducing interference. One example of combining techniques is interference rejection combining (IRC)....

AI Technical Summary

Benefits of technology

The invention provides an improved method for reducing interference in a multi-user receiver with multiple antenna elements. The method involves creating a spatial covariance matrix estimate from wideband antenna signals, determining a whitening filter based on the estimate, and removing the whitening from signals of predetermined users using an inverse matrix of the whitening filter. The method can be implemented in a receiver or a base station and allows for optimal signal combining. The technical effects of the invention include improved interference reduction and improved signal quality.

Problems solved by technology

This requires that the IRC operations need to be implemented separately for each user, thus increasing the complexity of a receiver.

Thus there arises a problem: the high bit rate users are seen as relatively high level interferers to low bit rate users and therefore taken into account when determining whitening weights.

As a consequence of this, in whitening, the combining of antenna signals is not optimal from the high data rate user's point of view.

The use of a non-optimal solution will diminish the uplink coverage of high data rate users and at the same time increase the user terminal's battery consumption for the high bit rate users.

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