Scheduler and scheduling method for transmitting data in mimo based wireless lan system

Abstract

A scheduler and scheduling method that may select a data transmission time interval and a data transmitting station are included in a multi-user Multiple Input Multiple Output (MIMO) communication system. An access point may include a receiver to receive channel measurement signals from stations using a plurality of receive antennas; a channel estimation unit to generate channel state matrices with respect to wireless channels formed from the stations to the receive antennas using the channel measurement signals; and a scheduler to select at least one transmitting station from the stations by considering the channel state matrices and a number of the receive antennas. The receiver may receive a data stream from the selected transmitting stations. Stations receive identifiers corresponding to transmitting stations and/or transmitting antennas to identify stations or antennas for transmitting data streams to the access point.

What is claimed is: 
     
         1 . An access point, comprising:
 a plurality of receive antennas;   a receiver to receive a channel measurement signal from at least one station, the channel measurement signal including an orthogonal code or a pseudo-noise (PN) code having an offset;   a channel estimation unit to generate a channel state matrix with respect to one or more wireless channels formed from the at least one station to the plurality of receive antennas using the received channel measurement signal; and   a scheduler to select at least one station of the at least one station to transmit one or more data streams according to the channel state matrix and a number of the receive antennas,   wherein the receiver receives the one or more data streams transmitted from the at least one selected station and identifies the channel measurement signal using the orthogonal code or the offset of the PN code.   
     
     
         2 . The access point of  claim 1 , wherein:
 the at least one selected station comprises a plurality of transmit antennas, and   the scheduler selects the at least one selected station according to a number of the transmit antennas.   
     
     
         3 . The access point of  claim 1 , wherein the scheduler determines a number of the one or more data streams to be simultaneously received by the receive antennas. 
     
     
         4 . The access point of  claim 3 , wherein the number of the one or more data streams is equal to or less than a number of the receive antennas. 
     
     
         5 . The access point of  claim 3 , wherein the number of the one or more data streams is equal to or less than a number of the transmit antennas. 
     
     
         6 . The access point of  claim 1 , wherein the scheduler determines at least one data reception time interval for receiving the one or more data streams from the at least one selected station. 
     
     
         7 . The access point of  claim 1 , further comprising:
 a signal-to-interference and noise ratio (SINR) measurement unit to measure an SINR with respect to the one or more wireless channels based on the channel measurement signal.   
     
     
         8 . The access point of  claim 1 , further comprising:
 a transmitter to transmit an identifier of the at least one selected station to the other of the at least one station.   
     
     
         9 . A station, comprising:
 a transmitter to transmit, using at least one transmit antenna, a channel measurement signal to an access point having a plurality of receive antennas, the channel measurement signal including an orthogonal code or a pseudo-noise (PN) code having an offset; and   a receiver to receive an identifier of a station selected by the access point based on the channel measurement signal and a number of the receive antennas,   wherein, if the received identifier corresponds to an identifier of the selected station, the transmitter transmits one or more data streams to the access point based on the identifier.   
     
     
         10 . The station of  claim 9 , wherein the received identifier is included in a data frame. 
     
     
         11 . The station of  claim 10 , wherein the receiver receives an indicator to indicate whether an identifier of a station other than the selected station is included in the data frame. 
     
     
         12 . The station of  claim 9 , wherein:
 the receiver receives channel measurement signal allocation information from the access point, and   the transmitter generates the channel measurement signal based on the channel measurement signal allocation information.   
     
     
         13 . The station of  claim 9 , wherein:
 the identifier identifies a data transmit antenna, and   if the identifier corresponds to one antenna of the at least one transmit antenna, the transmitter transmits the one or more data streams by considering the identifier of the data transmit antenna.   
     
     
         14 . The station of  claim 9 , wherein:
 the receiver receives, from the access point, data transmission time interval information for the selected station, and   the transmitter transmits the one or more data streams based on the data transmission time interval information.   
     
     
         15 . A method for receiving data, comprising:
 receiving, using at least one receive antenna, a channel measurement signal from at least one station, the channel measurement signal including an orthogonal code or a pseudo-noise (PN) code having an offset;   generating, using the received channel measurement signal, a channel state matrix with respect to one or more wireless channels formed from at least one of the stations to the plurality of receive antennas;   selecting at least one station of the at least one station to transmit one or more data streams according to the channel state matrix and a number of the receive antennas; and   receiving the one or more data streams from the at least one selected station,   wherein the channel measurement signal is identified by the orthogonal code or the offset of the PN code.   
     
     
         16 . The method of  claim 15 , wherein:
 the at least one selected station comprise a plurality of transmit antennas, and the at least one selected station is selected according to a number of the transmit antennas.   
     
     
         17 . The method of  claim 15 , further comprising:
 determining a number of the one or more data streams to be simultaneously received by the at least one receive antenna.   
     
     
         18 . The method of  claim 17 , wherein the number of the one or more data streams is equal to or less than a number of the at least one receive antenna. 
     
     
         19 . The method of  claim 16 , wherein the number of the one or more data streams is equal to or less than a number of the transmit antennas. 
     
     
         20 . The method of  claim 15 , further comprising:
 determining a data reception time interval for receiving data streams from the at least one selected station.   
     
     
         21 . A method for transmitting data by a station, comprising:
 transmitting, using at least one transmit antenna of the station, a channel measurement signal to an access point having a plurality of receive antennas, the channel measurement signal including an orthogonal code or a pseudo-noise (PN) code having an offset;   receiving an identifier of a station selected by the access point based on the channel measurement signal and a number of the receive antennas;   determining a data transmission rate by considering a number of the transmit antennas and a number of the receive antennas; and   if the received identifier corresponds to an identifier of the selected station, transmitting one or more data streams to receive antennas of the access point based on the data transmission rate.   
     
     
         22 . The method of  claim 21 , wherein the received identifier is included in a data frame. 
     
     
         23 . The method of  claim 22 , wherein the data frame comprises an indicator indicating whether an identifier of a station other than the selected station is included in the data frame.