Method and System for a Double Search User Group Selection Scheme With Range Reduction in TDD Multiuser MIMO Downlink Transmission

Abstract

Certain aspects of a method and system for processing signals in a communication system may include maximizing system capacity for a time division duplex (TDD) multiple-input multiple-output (MIMO) system, based on reducing a search range within which to find a group of signals having maximum channel gain. At least one of: a first signal for a first user and a second signal for a second user may be selected, which are both within the reduced search range, and which provides a maximum system capacity. The first signal for the first user may be selected from the reduced search range corresponding to a channel gain that is greater than a channel gain corresponding to a remaining portion of the reduced search range. The reduced search range may be generated by sorting a plurality of signals based on a channel gain corresponding to each of the plurality of signals.

1 . A method for processing signals in a communication system, comprising:
 identifying a user group of M users based on a performance criterion associated with the user group;   processing a plurality of user data symbols to separate signals intended for the M users in the user group; and   transmitting the separate signals to the user group of M users using one or more antennas.   
     
     
         2 . The method of  claim 1 , wherein the group of M users comprises a subset of a total number of users in the communication system. 
     
     
         3 . The method of  claim 1 , wherein M is an integer that is less than a number of the one or more antennas. 
     
     
         4 . The method of  claim 1 , wherein the performance criterion comprises a system capacity associated with the group of M users. 
     
     
         5 . The method of  claim 1 , wherein identifying the user group of M users comprises using a double search user group selection scheme. 
     
     
         6 . The method of  claim 5 , wherein the double search user group selection scheme comprises:
 sorting a plurality of users in the communication system according to a channel power associated with each of the plurality of users in the communication system;   initializing a system capacity to a value of a system capacity associated with a first user having the greatest channel power of the plurality of users in the communication system;   determining that a second user has a greater system capacity than the system capacity of the first user; and   selecting the second user for the group of M users.   
     
     
         7 . The method of  claim 5 , wherein identifying the user group further comprises range reduction. 
     
     
         8 . The method of  claim 7 , wherein range reduction comprises selecting the group of M users from among a subset L of a plurality of users in the communication system. 
     
     
         9 . The method of  claim 8 , further comprising updating the subset L in real time based on online channel measurements. 
     
     
         10 . The method of  claim 1 , wherein processing the plurality of user data symbols comprises the user data symbols to separate signals intended for the M users in the user group such that interference from other users is mitigated for each user. 
     
     
         11 . A communication system, comprising:
 a user scheduler configured to identify a user group of M users based on a performance criterion associated with the user group; and   a beam former comprising circuitry configured to:
 process a plurality of user data symbols to separate signals intended for the M users in the user group; and 
 transmit the separate signals to the user group of M users using one or more antennas. 
   
     
     
         12 . The communication system of  claim 11 , wherein the user scheduler is further configured to identify the group of M users by determining a subset of a total number of users in the communication system. 
     
     
         13 . The communication system of  claim 11 , the user scheduler is further configured to determine the group of M users such that M is an integer that is less than a number of the one or more antennas. 
     
     
         14 . The communication system of  claim 11 , wherein the user scheduler is further configured to identify the group of M users using a system capacity associated with the group of M users. 
     
     
         15 . The communication system of  claim 11 , wherein the user scheduler is further configured to identify the user group of M users using a double search user group selection scheme. 
     
     
         16 . The communication system of  claim 15 , wherein the user scheduler is further configured to use the double search user group selection scheme that comprises:
 sorting a plurality of users in the communication system according to a channel power associated with each of the plurality of users in the communication system;   initializing a system capacity to a value of a system capacity associated with a first user having the greatest channel power of the plurality of users in the communication system;   determining that a second user has a greater system capacity than the system capacity of the first user; and   selecting the second user for the group of M users.   
     
     
         17 . The communication system of  claim 15 , wherein the user scheduler is configured to identify the user group further using range reduction. 
     
     
         18 . The communication system of  claim 17 , wherein the user scheduler is configured to perform range reduction by selecting the group of M users from among a subset L of a plurality of users in the communication system. 
     
     
         19 . The communication system of  claim 18 , the user scheduler is further configured to update the subset L in real time based on online channel measurements. 
     
     
         20 . The communication system  claim 11 , wherein the beam former is further configured to process the plurality of user data symbols to separate signals intended for the M users in the user group such that interference from other users is mitigated for each user.