Rake receiver for CDMA wireless communications

Abstract

An apparatus for performance improvement of a digital wireless receiver, having a plurality of signals, has a processing circuit and a weight generation circuit. The processing circuit provides a processed signal, wherein a plurality of weights is applied to a plurality of signals producing a plurality of weighted signals and the plurality of weighted signals are combined to provide the processed signal. In the weight generation circuit the plurality of weights are generated as a function of a conjugate of channel estimate of a corresponding signal of the plurality of signals and a variance of the corresponding signal. A method implementing the present invention is also described.

What is claimed  
     
         1 . A method for performance improvement of a digital wireless rake receiver having a plurality of finger signals comprising the following steps: 
 determining a corresponding conjugate of channel estimate for each finger signal of the plurality of finger signals;    determining a corresponding variance for said each finger signal of the plurality of finger signals;    generating a plurality of weights wherein weights are generated as a function of said corresponding conjugate of channel estimate and said corresponding variance;    applying said plurality of weights to the plurality of finger signals producing a plurality of weighted signals; and,    combining said plurality of weighted signals producing a processed signal.    
     
     
         2 . The method as recited in  claim 1  wherein the step of determining a corresponding variance further comprises estimating finger variance as a function of de-spreader output of traffic channel.  
     
     
         3 . The method as recited in  claim 1  wherein the step of determining a corresponding variance further comprises estimating finger variance as a function of de-spreader output of pilot channel.  
     
     
         4 . The method as recited in  claim 3  wherein the pilot channel comprises a pilot code channel.  
     
     
         5 . The method as recited in  claim 3  wherein the pilot channel comprises pilot symbols.  
     
     
         6 . The method as recited in  claim 1  wherein said corresponding variance is V l =E└|T l−E[T   l ] 2   540  where V l  is the variance, E is the expectation operation, and T l  is de-spreader output at an l th  path for traffic channel.  
     
     
         7 . The method as recited in  claim 1  wherein said corresponding variance is V l =E└|P l −E[P l ] 2 ┘ where V l  is the variance, E is the expectation operation and P l  is de-spreader output at an l th  path for pilot channel.  
     
     
         8 . An apparatus for performance improvement of a digital wireless rake receiver having a plurality of finger signals comprising: 
 a processing circuit for processing the plurality of finger signals and providing a processed signal, wherein a plurality of weights is applied to said plurality of finger signals producing a plurality of weighted signals and said plurality of weighted signals are combined to provide said processed signal; and    a weight generation circuit for generating said plurality of weights, wherein said plurality of weights are generated as a function of a conjugate of channel estimate of a corresponding finger signal of said plurality of finger signals and a variance of said corresponding finger signal.    
     
     
         9 . The apparatus as recited in  claim 8  wherein said variance of said corresponding finger signal is estimated as a function of de-spreader output of traffic channel.  
     
     
         10 . The apparatus as recited in  claim 8  wherein said variance of said corresponding finger signal is estimated as a function of de-spreader output of pilot channel.  
     
     
         11 . The apparatus as recited in  claim 10  wherein said pilot channel comprises a pilot code channel.  
     
     
         12 . The apparatus as recited in  claim 10  wherein said pilot channel comprises pilot symbols.  
     
     
         13 . The apparatus as recited in  claim 8  wherein said variance of said corresponding finger signal is V l =E└|T l −E[T l ] 2 ┘ where V l  is the variance, E is the expectation operation and T l  is de-spreader output at an l th  path for traffic channel.  
     
     
         14 . The rake receiver as recited in  claim 8  wherein said variance of said corresponding finger signal is V l =E└|P l −E[P l ] 2 ┘ where V l  is the variance, E is the expectation operation and P l  is de-spreader output at an l th  path for pilot channel.  
     
     
         15 . A signal processor for a wireless receiver having a plurality of signals, the signal processor comprising: 
 a processing circuit for processing the plurality of signals and providing a processed signal, wherein a plurality of weights is applied to the plurality of signals producing a plurality of weighted signals and said plurality of weighted signals are combined to provide said processed signal; and    a weight generation circuit for generating said plurality of weights, wherein said plurality of weights are generated as a function of a conjugate of channel estimate of a corresponding signal of said plurality of signals and a variance of said corresponding signal.    
     
     
         16 . The signal processor as recited in  claim 15  wherein said variance of said corresponding signal is estimated as a function of de-spreader output of traffic channel.  
     
     
         17 . The signal processor as recited in  claim 15  wherein said variance of said corresponding signal is estimated as a function of de-spreader output of pilot channel.  
     
     
         18 . The signal processor as recited in  claim 17  wherein said pilot channel comprises a pilot code channel.  
     
     
         19 . The signal processor as recited in  claim 15  wherein said pilot channel comprises pilot symbols.  
     
     
         20 . The signal processor as recited in  claim 15  wherein said variance of said corresponding signal is V l =E└|T l −E[T l ] 2 ┘ where V l  is the variance, E is the expectation operation and T l  is de-spreader output at an l th  path for traffic channel.  
     
     
         21 . The signal processor as recited in  claim 15  wherein said variance of said corresponding signal is V l =E└|P l −E[P l ] 2 ┘ where V l  is the variance, E is the expectation operation and P l  is de-spreader output at an l th  path for pilot channel.