Method and apparatus for regulation of the effective noise figure in a CDMA receiver

Abstract

The present invention relates to a method for effecting regulation of the effective noise figure of a CDMA (Code Division Multiple Access) receiver. The regulation process can be used to control the receiver during the activation/deactivation of a cell/sector in a CDMA wireless system and during normal operation when the service area of the cell/sector needs to enlarge or shrink. In a most preferred embodiment the CDMA receiver includes a source of pseudo-random noise that is injected in the received signal, downstream of the signal digitization stage. A power detector measures the power in the received digitized signal and a program logic determines the amount of noise figure degradation to be applied. The actual noise power regulation is effected by multiplying the output of the noise generator by a weighing factor. In a multi-channel CDMA system, each channel is provided with an independent system to regulate the effective noise power figure degradation, thus allowing to effect a noise figure regulation on a channel by channel basis.

We claim:  
     
         1 . A CDMA receiver, comprising: 
 an input for receiving an RF signal;    an analog signal processing stage connected to said input, said analog processing stage processing said RF signal that includes a plurality of components separable from one another; and    a plurality of channels connected to said analog processing stage, each channel receiving a respective component of said signal, each channel including an effective noise figure regulation means to regulate an effective noise figure the component processed by the channel.    
     
     
         2 . The receiver as defined in    claim 1   , wherein said effective noise figure regulation means comprising a noise generator to generate a noise signal and means to introduce the noise signal into the component of the signal.  
     
     
         3 . The receiver as defined in    claim 2    wherein said noise generator produces either one of a random and pseudo-random noise.  
     
     
         4 . The receiver as defined in    claim 3   , wherein said noise power regulation means includes means for measuring a power of the component of the signal.  
     
     
         5 . The receiver as defined in    claim 4   , wherein said power regulation means includes means to regulate a variance of the noise signal.  
     
     
         6 . A method for regulating an effective noise figure of a signal in a multi-channel CDMA receiver, said method comprising the steps of: 
 acquiring a signal;    separating said signal into a plurality of components;    introducing each component of said signal in a respective channel of the CDMA receiver; and    regulating an effective noise power figure of the signal component processed in the channel independently from other channels of the CDMA receiver.    
     
     
         7 . The method as defined in    claim 1   , wherein said method includes the steps of generating a noise signal and introducing the noise signal into the signal component.  
     
     
         8 . The method as defined in    claim 7    wherein said noise generator produces either one of a random and pseudo-random noise.  
     
     
         9 . The method as defined in    claim 8   , comprising the step of measuring a power of the signal component to compute a variance of the noise signal to introduce in the signal component.