Multi-user multiple input multiple output wireless communications

Abstract

A method implemented in a user equipment used in a wireless communications system is disclosed. The method comprises receiving from a base station an indication of a first modulation type for the user equipment, receiving from the base station a first data signal for the user equipment, receiving from the base station an indication of a minimum time-frequency unit that is assigned to another user equipment, receiving a second data signal for said another user equipment, where a second modulation type for said another user equipment is unknown to the user equipment, and cancelling and suppressing interference by using the minimum time-frequency unit. Other methods, systems, and apparatuses also are disclosed.

What is claimed is: 
     
         1 . A method implemented in a user equipment used in a wireless communications system, the method comprising:
 receiving from a base station an indication of a first modulation type for the user equipment;   receiving from the base station a first data signal for the user equipment;   receiving from the base station an indication of a minimum time-frequency unit that is assigned to another user equipment;   receiving a second data signal for said another user equipment, where a second modulation type for said another user equipment is unknown to the user equipment; and   cancelling and suppressing interference by using the minimum time-frequency unit.   
     
     
         2 . The method as in  claim 1 ,
 wherein each of the first modulation type and the second modulation type is either one of 4-QAM (quadrature amplitude modulation), 16-QAM, or 64-QAM.   
     
     
         3 . The method as in  claim 1 ,
 wherein the second modulation type is decided by assuming that the second modulation type remains constant within the minimum time-frequency unit.   
     
     
         4 . The method as in  claim 1 ,
 wherein the second modulation type is decided through modulation classification algorithm.   
     
     
         5 . The method as in  claim 1 , further comprising:
 processing the first data signal and the second data signal by using the first modulation type and the second modulation type to perform interference cancellation.   
     
     
         6 . The method as in  claim 5 , wherein the processing comprises:
 jointly demodulating the first data signal and the second data signal by using the first modulation type and the second modulation type.   
     
     
         7 . The method as in  claim 1 , further comprising:
 generating a log-likelihood ratio (LLR) for the user equipment.   
     
     
         8 . A method implemented in a base station used in a wireless communications system, the method comprising:
 transmitting to a user equipment an indication of a first modulation type for the user equipment;   transmitting to the user equipment a first data signal for the user equipment; and   transmitting to the user equipment an indication of a minimum time-frequency unit that is assigned to a another user equipment,   wherein the user equipment receives a second data signal for said another user equipment, where a second modulation type for said another user equipment is unknown to the user equipment, and   wherein the user equipment cancels and suppresses interference by using the minimum time-frequency unit.   
     
     
         9 . The method as in  claim 8 ,
 wherein each of the first modulation type and the second modulation type is either one of 4-QAM (quadrature amplitude modulation), 16-QAM, or 64-QAM.   
     
     
         10 . The method as in  claim 8 ,
 wherein the second modulation type is decided by assuming that the second modulation type remains constant within the minimum time-frequency unit.   
     
     
         11 . The method as in  claim 8 ,
 wherein the second modulation type is decided through modulation classification algorithm.   
     
     
         12 . The method as in  claim 8 ,
 wherein the processor processes the first data signal and the second data signal by using the first modulation type and the second modulation type to perform interference cancellation.   
     
     
         13 . The method as in  claim 12 ,
 wherein the processor jointly demodulates the first data signal and the second data signal by using the first modulation type and the second modulation type.   
     
     
         14 . The method as in  claim 8 ,
 wherein the processor generates a log-likelihood ratio (LLR) for the user equipment.   
     
     
         15 . A method implemented in a wireless communications system, the method comprising:
 transmitting from a base station to a user equipment an indication of a first modulation type for the user equipment;   transmitting from the base station to the user equipment a first data signal for the user equipment;   transmitting from the base station to the user equipment an indication of a minimum time-frequency unit that is assigned to another user equipment;   transmitting to the user equipment a second data signal for said another user equipment, where a second modulation type for said another user equipment is unknown to the user equipment; and   cancelling and suppressing interference by using the minimum time-frequency unit.   
     
     
         16 . The method as in  claim 15 ,
 wherein each of the first modulation type and the second modulation type is either one of 4-QAM (quadrature amplitude modulation), 16-QAM, or 64-QAM.   
     
     
         17 . The method as in  claim 15 ,
 wherein the second modulation type is decided by assuming that the second modulation type remains constant within the minimum time-frequency unit.   
     
     
         18 . The method as in  claim 15 ,
 wherein the second modulation type is decided through modulation classification algorithm.   
     
     
         19 . The method as in  claim 15 , further comprising:
 processing, at the user equipment, the first data signal and the second data signal by using the first modulation type and the second modulation type to perform interference cancellation.   
     
     
         20 . The method as in  claim 19 , wherein the processing comprises:
 jointly demodulating the first data signal and the second data signal by using the first modulation type and the second modulation type.