Base Station and Wireless Communication System

Abstract

It is provided a wireless communication system comprising base stations that transmit data to a terminal with cooperation by the base stations. The terminal communicates with the base stations. The terminal periodically transmits, to one of the base stations, information necessary for data transmission from a single base station out of the base stations. Each of the base stations determines whether the terminal needs data transmission through a cooperation among the base stations, and transmits a cooperation information transmission instruction to the terminal, which includes information necessary to execute the data transmission in order to cooperate among the base stations in the case where it is determined that the terminal needs the data transmission through the cooperation among the base stations. The terminal transmits the cooperation information to the base stations in a case of receiving the cooperation information transmission instruction.

1 . A wireless communication system comprising a plurality of base stations that transmit data to a communication terminal with cooperation by the plurality of base stations, wherein
 the communication terminal communicates with the plurality of base stations,   the communication terminal periodically transmits, to one of the plurality of base stations, information necessary for data transmission from a single base station out of the plurality of base stations,   each of the plurality of base stations is configured to:   determine whether the communication terminal needs data transmission through a cooperation among the plurality of base stations; and   transmit a cooperation information transmission instruction to the communication terminal, which includes information necessary to execute the data transmission in order to cooperate among the plurality of base stations in the case where it is determined that the communication terminal needs the data transmission through the cooperation among the plurality of base stations, and   the communication terminal transmits the cooperation information to the plurality of base stations in a case of receiving the cooperation information transmission instruction.   
     
     
         2 . The wireless communication system according to  claim 1 , wherein
 the each of the plurality of base stations is configured to:   determine whether the data transmission from the single base station is executable for the communication terminal in the case where determining whether the communication terminal needs the data transmission through the cooperation among the plurality of base stations;   transmit the cooperation information transmission instruction to the communication terminal in the case where it is determined that the data transmission from the single base station is not executable for the communication terminal; and   allocate wireless resources for the data transmission from the single base station to the communication terminal, based on the received information necessary for the data transmission from the single base station in the case where it is determined that the data transmission from the single base station is executable for the communication terminal.   
     
     
         3 . The wireless communication system according to  claim 2 , further comprising a cooperation scheduler, which is configured to:
 allocate the communication terminal wireless resources for the data transmission through the cooperation among the plurality of base stations, based on the cooperation information received by the plurality of base stations; and   transmit a result of the wireless resource allocation for the data transmission through the cooperation among the plurality of base stations to the plurality of cooperating base stations.   
     
     
         4 . The wireless communication system according to  claim 3 , wherein,
 the communication terminal transmits the cooperation information to the plurality of base stations which includes information necessary to execute data transmission to one communication terminal through the cooperation among the plurality of base stations, and information necessary to execute data transmission to a plurality of the communication terminals through the cooperation among the plurality of base stations, and   the each of the plurality of base stations is configured to determine whether the data transmission to the one communication terminal through the cooperation among the plurality of base stations or the data transmission to the plurality of communication terminals through the cooperation among the plurality of base stations is to be executed based on the received cooperation information.   
     
     
         5 . The wireless communication system according to  claim 3 , wherein,
 the each of the plurality of base stations is configured to:   determine which of information necessary to execute data transmission to one communication terminal through the cooperation among the plurality of base stations and information necessary to execute data transmission to a plurality of the communication terminals through the cooperation among the plurality of base stations is needed, and   transmit the cooperation information transmission instruction based on the determination.   
     
     
         6 . The wireless communication system according to  claim 3 , wherein,
 the wireless resources are divided into a plurality of subchannels,   the cooperation scheduler is configured to allocate a predetermined specific subchannel to the communication terminal as the wireless resources for the data transmission through the cooperation among the plurality of base stations, and   the base station is configured to set information about the predetermined specific subchannel in the cooperation information transmission instruction.   
     
     
         7 . The wireless communication system according to  claim 3 , wherein,
 the wireless resources are divided into a plurality of subchannels,   the cooperation scheduler is configured to determine at least one of the plurality of subchannels which is to be allocated as the wireless resources for the data transmission through the cooperation among the plurality of base stations, and   the base station is configured to transmit the cooperation information transmission instruction which includes information about the determined subchannel.   
     
     
         8 . The wireless communication system according to  claim 2 , wherein the each of the plurality of base stations is configured to refer to a result of the wireless resource allocation to the communication terminal for the data transmission from the single base station, and determine whether the data transmission from the single base station is executable for the communication terminal. 
     
     
         9 . The wireless communication system according to  claim 2 , wherein the each of the plurality of base stations is configured to refer to the information necessary for the data transmission from the single base station which is transmitted from the communication terminal, and determine whether the data transmission from the single base station is executable for the communication terminal. 
     
     
         10 . The wireless communication system according to  claim 2 , wherein the each of the plurality of base stations is configured to refer to traffic information of the communication terminal, and determine whether the data transmission from the single base station is executable for the communication terminal. 
     
     
         11 . The wireless communication system according to  claim 2 , wherein the each of the plurality of base stations is configured to refer to ACK information and NACK information which are transmitted from the communication terminal, and determine whether the data transmission from the single base station is executable for the communication terminal. 
     
     
         12 . The wireless communication system according to  claim 2 , wherein the cooperation information includes at least one of a channel quality, the number of MIMO ranks, a precoding matrix desired by the communication terminal, and a channel matrix in the data transmission through the cooperation among the plurality of base stations. 
     
     
         13 . A base station installed in a wireless communication system that transmits data to a communication terminal through cooperation among a plurality of the base stations, wherein,
 the communication terminal communicates with the base station,   the communication terminal periodically transmits, to the base station, information necessary for data transmission from a single base station out of the plurality of base stations,   the base station is configured to:   determine whether the communication terminal needs data transmission through the cooperation among the plurality of base stations; and   transmit a cooperation information transmission instruction to the communication terminal, which includes information necessary to execute the data transmission order to cooperate among the plurality of base stations in the case where it is determined that the communication terminal needs the data transmission through the cooperation among the plurality of base stations.   
     
     
         14 . The base station according to  claim 13 , wherein the base station is further configured to:
 determine whether the data transmission from the single base station is executable for the communication terminal in the case where determining whether the communication terminal needs the data transmission through the cooperation among the plurality of base stations;   transmit the cooperation information transmission instruction to the communication terminal in the case where it is determined that the data transmission from the single base station is not executable for the communication terminal;   receive the cooperation information transmitted from the communication terminal;   allocate wireless resources for the data transmission through the cooperation among the plurality of base stations based on the received cooperation information;   transmit a result of the wireless resource allocation for the data transmission through the cooperation among the plurality of base stations to the other base stations that cooperate with the base station; and   allocate wireless resources for the data transmission from the single base station to the communication terminal, based on the received information necessary for the data transmission from the single base station in the case where it is determined that the data transmission from the single base station is executable for the communication terminal.   
     
     
         15 . The base station according to  claim 14 ,
 wherein the cooperation information includes information necessary to execute data transmission to one communication terminal through the cooperation among the plurality of base stations, and information necessary to execute data transmission to a plurality of the communication terminals through the cooperation among the plurality of base stations, and   wherein, the base station is configured to determine whether the data transmission to the one communication terminal through the cooperation among the plurality of base stations or the data transmission to the plurality of communication terminals through the cooperation among the plurality of base stations is to be executed based on the received cooperation information.   
     
     
         16 . (canceled)