Method and apparatus for reducing multi-user processing in wireless communication systems

Abstract

A method and apparatus is disclosed for reducing multi-user processing at the receiver in wireless communication systems. Detected codes are grouped according to channel impulse response and a parent code is identified for each group of detected codes. A matrix A is constructed and joint detection is performed using the identified parent codes. Data symbols of the detected codes are obtained from the data symbols of the identified parent codes.

1 . A method for reducing processing complexity of multi-user detection in a receiver in a code division multiple access (CDMA) wireless communication system, the method comprising:
 detecting codes used to transmit data symbols;   identifying a parent code for the detected codes;   performing joint detection using the parent code;   obtaining the data symbols carried by the codes;   identifying a channel impulse response for each of the detected codes; and   grouping the detected codes having the same channel impulse response, wherein the parent code is identified for each group of codes.   
     
     
         2 . The method of  claim 1  wherein the code is an orthogonal variable spreading factor (OVSF) code. 
     
     
         3 . The method of  claim 1  further comprising:
 constructing a channel convolution matrix using the identified parent code, wherein the joint detection is performed by using the channel convolution matrix. 
 
     
     
         4 . The method of  claim 1  wherein a channel convolution matrix is constructed for each group of codes using the identified parent code for each group of codes, wherein the joint detection is performed by using the channel convolution matrix. 
     
     
         5 . The method of  claim 1  wherein a detected code having unique channel impulse responses is considered as a parent code. 
     
     
         6 . A receiver for reducing processing complexity of multi-user detection in a code division multiple access (CDMA) wireless communication system, the receiver comprising:
 a code detector for detecting codes used to transmit data symbols;   a parent code locator for identifying a parent code for the detected codes;   a joint detector for performing joint detection using the parent code;   a post data converter for obtaining the data symbols carried by the codes;   a channel estimator for identifying a channel impulse response for each of the detected codes; and   a code grouper for grouping the detected codes having the same channel impulse response, wherein the parent code is identified for each group of codes.   
     
     
         7 . The receiver of  claim 6  wherein the code is an orthogonal variable spreading factor (OVSF) code. 
     
     
         8 . The receiver of  claim 6  further comprising:
 a channel convolution matrix constructor for constructing a channel convolution matrix using the identified parent code, wherein the joint detector performs the joint detection using the channel convolution matrix. 
 
     
     
         9 . The receiver of  claim 6  further comprising:
 a channel convolution matrix constructor for constructing a channel convolution matrix for each group of codes using the identified parent code for each group of codes, wherein the joint detector performs the joint detection using the channel convolution matrix. 
 
     
     
         10 . The receiver of  claim 6  wherein the parent code locator identifies a detected code having unique channel impulse responses as a parent code.