Multi-user detection using an adaptive combination of joint detection and successive interference cancellation

Abstract

A time division duplex communication system using code division multiple access transmits a plurality of data signals over a shared spectrum in a time slot. A combined signal is received over the shared spectrum in the time slot. The plurality of data signals are grouped into a plurality of groups. The combined signal is matched filtered based on in part symbol responses associated with the data signals of one of the groups. Data from each data signal in the one group is jointly detected. An interference signal is constructed based on in part the one group detected data. The constructed interference signal is subtracted from the combined signal. Data from the other groups is detected by processing the subtracted signal.

1 . A method for use in a receiver for receiving a plurality of data signals transmitted over a shared spectrum in a time slot in a time division duplex communication system using code division multiple access, the method comprising: 
 receiving a combined signal over the shared spectrum in the time slot;    estimating a received power level for each data signal;    selectively grouping data signals of the plurality of data signals based on in part the received power level of the data signals into at least one group; and    separately detecting data within each group for that group's data signals; and    wherein the estimating the received power level for each data signal is based on in part a power level of a training sequence associated with each data signal.    
   
   
       2 . A method for use in a receiver for receiving a plurality of data signals transmitted over a shared spectrum in a time slot in a time division duplex communication system using code division multiple access, the method comprising: 
 receiving a combined signal over the shared spectrum in the time slot;    estimating a received power level for each data signal;    selectively grouping data signals of the plurality of data signals based on in part the received power level of the data signals into at least one group; and    separately detecting data within each group for that group's data signals;    wherein the estimating the received power level for each data signal is based on in part apriori knowledge at the receiver.    
   
   
       3 . The method of  claim 1  wherein the selectively grouping data signals groups data signals within a certain threshold power level into a group.  
   
   
       4 . The method of  claim 3  wherein the certain threshold power level is one decibel.  
   
   
       5 . A method for use in a receiver for receiving a plurality of data signals transmitted over a shared spectrum in a time slot in a time division duplex communication system using code division multiple access, the method comprising: 
 receiving a combined signal over the shared spectrum in the time slot;    estimating a received power level for each data signal;    selectively grouping data signals of the plurality of data signals based on in part the received power level of the data signals into at least one group; and    separately detecting data within each group for that group's data signals;    wherein the selectively grouping data signals groups data signals within a certain threshold power level into a group and the certain threshold is adjusted to achieve a desired bit error rate at the receiver.    
   
   
       6 . The method of  claim 1  further comprising forcing all of the data signals into a single group to override the step of selectively grouping.  
   
   
       7 . The method of  claim 1  further comprising forcibly grouping each data signal into its own group to override the step of selectively grouping.