Interference reduction using low complexity antenna array

Abstract

Interference reduction is achieved within a communication device using a low complexity antenna array. In at least one embodiment, phase and magnitude values associated with an antenna element within a low complexity array are dynamically adjusted during device operation in a manner that enhances a predetermined quality criterion (e.g., SINR).

1 . A method for reducing interference in a communication device comprising: 
 providing a communication device having first and second antenna elements, said first antenna element having an adjustable weight;    applying a predetermined weight to said first antenna element;    estimating a combined channel response for said first and second antenna elements while said predetermined weight is being applied for a first base station of interest;    calculating individual channel responses for channels between said first and second antenna elements and said first base station of interest using said estimated combined channel response; and    determining a new weight for said first antenna element that enhances an interference-related quality criterion using said individual channel responses.    
   
   
       2 . The method of  claim 1  comprising: 
 repeating estimating a combined channel response and calculating individual channel responses for each of a plurality of base stations of interest.    
   
   
       3 . The method of  claim 1  wherein: 
 estimating a combined channel response includes identifying and using a pilot signal received from said first base station of interest.    
   
   
       4 . The method of  claim 1  wherein: 
 applying a predetermined weight includes forcing a magnitude associated with said first antenna element to zero.    
   
   
       5 . The method of  claim 1  wherein: 
 said interference-related quality criterion includes a signal to interference and noise ratio (SINR).    
   
   
       6 . A method for reducing interference in a communication device comprising: 
 providing a communication device having first and second antenna elements, said first antenna element having an adjustable weight;    applying a predetermined weight to said first antenna element during a present time period;    estimating a combined channel response for said first and second antenna elements while said predetermined weight is being applied for a first base station of interest;    calculating individual channel responses for channels between each of said first and second antenna elements and said first base station of interest for said present time period using said combined channel response;    determining a new weight for said first antenna element for said present time period that enhances an interference-related quality criterion using said individual channel responses; and    applying said new weight to said first antenna element during said present time period.    
   
   
       7 . The method of  claim 6  comprising: 
 repeating estimating a combined channel response and calculating individual channel responses for each of a plurality of base stations of interest before determining said new weight.    
   
   
       8 . The method of  claim 6  wherein: 
 calculating individual channel responses includes using antenna weight information from a previous time period.    
   
   
       9 . The method of  claim 6  wherein: 
 calculating individual channel responses includes using combined channel response information from a previous time period.    
   
   
       10 . The method of  claim 6  wherein: 
 calculating individual channel responses includes solving M equations in M unknowns, where M is an integer greater than  1 .    
   
   
       11 . The method of  claim 6  wherein: 
 calculating individual channel responses includes solving the following system of equations for C 1 (t=nT):            {               h   1     ⁡     (   t   )       =       W   ~     ⁢       C   1     ⁡     (   t   )                 t   ∈     [     nT   ,     nT   +   τ       ]                     h   1     ⁡     (   t   )       =       W       (     n   -   1     )     ⁢   T       ⁢       C   1     ⁡     (   t   )                 t   ∈     [           (     n   -   1     )     ⁢   T     +   τ     ,   nT     )                     where h 1 (t) is the estimated combined channel response for the first base station of interest at time t, W (n−1)T  is the calculated vector gain of the antenna elements during previous period [(n−1)T+τ, nT), C 1 (t) is the matrix channel response of the first base station of interest for each of the antenna elements at time t, and {tilde over (W)} is the vector gain of the antennas using the predetermined weight.    
   
   
       12 . The method of  claim 6  wherein: 
 said interference-related quality criterion includes a signal to interference and noise ratio (SINR).    
   
   
       13 . The method of  claim 6  further comprising: 
 repeating applying a predetermined weight, estimating a combined channel response, calculating individual channel responses, determining a new weight, and applying said new weight for a subsequent time period.    
   
   
       14 . A communication device comprising: 
 first and second antenna elements, said first antenna element having an adjustable weight;    a combiner to combine outputs of said first and second antenna elements to generate a combined signal; and    a controller to control said adjustable weight of said first antenna element, said controller including: 
 a first unit to determine individual channel responses for said first and second antenna elements for each of a plurality of base stations of interest; and  
 a second unit to determine a weight for said first antenna element that optimizes an interference-related quality criterion using the individual channel responses.  
   
   
   
       15 . The communication device of  claim 14  comprising: 
 at least one additional antenna element, wherein said combiner combines outputs of said first antenna element, said second antenna element, and said at least one additional antenna element to generate said combined signal and wherein said first unit determines individual channel responses for said first antenna element, said second antenna element, and said at least one additional antenna element for each of the base stations of interest.    
   
   
       16 . The communication device of  claim 14  wherein: 
 said controller repeatedly updates said weight of said first antenna element.    
   
   
       17 . The communication device of  claim 16  wherein: 
 said controller updates said weight of said first antenna element at intervals that depend upon a Doppler rate associated with said communication device.    
   
   
       18 . The communication device of  claim 14  wherein: 
 said interference-related quality criterion includes a signal to interference and noise ratio (SINR).    
   
   
       19 . The communication device of  claim 14  wherein: 
 said first unit regularly applies a predetermined weight to said first antenna element for use in determining said individual channel responses.    
   
   
       20 . The communication device of  claim 14  wherein: 
 said first unit determines said individual channel responses for said first and second antenna elements using a combined channel response for said first and second antenna elements for each base station of interest.