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.

1 . A method for reducing an 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 method comprising: 
 creating a spatial covariance matrix estimate from wideband antenna signals by sampling, arranging sampled values into a signal vector and by multiplying the signal vector by a conjugate transpose vector of the signal vector,    determining a whitening filter based on a spatial covariance matrix estimate;    whitening received signals by using the whitening filter;    removing whitening from signals of predetermined users by using an inverse matrix of a matrix used in the whitening filter; and    conveying whitened signals and signals from which the whitening has been removed to a receiver element, which carries out multi-path combining and multi-antenna combining.    
     
     
         2 . The method of  claim 1 , wherein the said whitening is carried out by matrix vector multiplication.  
     
     
         3 . The method of  claim 1 , further comprising: 
 using maximum ratio combining by the receiver element for performing multi-path combining and multi-antenna combining according to a Rake principle.    
     
     
         4 . The method of  claim 1 , wherein said determining comprises determining the whitening filter by using a Cholesky decomposition.  
     
     
         5 . The method of  claim 1 , wherein the said removing comprises removing the whitening from the predetermined users which are determined based on a bit rate threshold.  
     
     
         6 . A multi-user receiver which uses at least two antenna elements and in which an influence of interference is reduced, the multi-user receiver comprising: 
 pre-filtering means for pre-filtering a wideband antenna signal, the pre-filtering means being determined based on a spatial covariance matrix estimate, the 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 a conjugate transpose vector of the signal vector;    removing means for removing whitening from signals of predetermined users by using an inverse matrix of matrix used in a whitening filter; and    performing means for performing multi-path combining and multi-antenna combining.    
     
     
         7 . A multi-user receiver in which an influence of interference is reduced, the multi-user receiver comprising: 
 a pre-filter whitening a wideband antenna signal, the pre-filter being determined based on a spatial covariance matrix estimate, the 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 a conjugate transpose vector of the signal vector;    a whitening removing arrangement removing the whitening from signals of predetermined users by using an inverse matrix of a matrix used in a whitening filter; and    a receiver element performing multi-path combining and multi-antenna combining.    
     
     
         8 . The multi-user receiver of  claim 6 , wherein the whitening is carried out by complex matrix multiplication.  
     
     
         9 . The multi-user receiver of  claim 8 , wherein the receiver element performing the multi-path combining and the multi-antenna combining comprises a maximum ratio combiner.  
     
     
         10 . The multi-user receiver of  claim 6 , wherein the performing means for performing the multi-path combining and the multi-antenna combining comprises a maximum ratio combiner.  
     
     
         11 . The multi-user receiver of  claim 6 , wherein the multi-user receiver further comprises determining means for determining the predetermined users from whom whitening is removed based on a bit rate threshold.  
     
     
         12 . The multi-user receiver of  claim 8 , wherein the multi-user receiver further comprises determining means for determining the predetermined users from whom the whitening is removed based on a bit rate threshold.  
     
     
         13 . A base station comprising a multi-user receiver, the multi-user receiver uses at least two antenna elements and, in the base station, an influence of an interference is reduced, the base station comprising: 
 pre-filtering means for pre-filtering a wideband antenna signal, the pre-filtering means being determined based on a spatial covariance matrix estimate, the 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 a conjugate transpose vector of the signal vector;    removing means for removing whitening from signals of predetermined users by using an inverse matrix of a matrix used in a whitening filter; and    performing means for performing multi-path combining and multi-antenna combining.    
     
     
         14 . A base station comprising a multi-user receiver, the multi-user receiver uses at least two antenna elements and, in the base station, an influence of an interference is reduced, the base station comprising: 
 a pre-filter whitening a wideband antenna signal, the pre-filter being determined based on a spatial covariance matrix estimate, the 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 a conjugate transpose vector of the signal vector;    a whitening removing arrangement removing whitening from signals of predetermined users by using an inverse matrix of a matrix used in a whitening filter and    an element performing multi-path combining and multi-antenna combining.