Sub-channel allocation in orthogonal frequency division multiplex wlan

Abstract

A first communication device receives one or more downlink orthogonal frequency division multiplexing (OFDM) data units transmitted by a second communication device via one or more respective sub-channels of an OFDM communication channel. The first communication device identifies the one or more sub-channels of the OFDM communication channel on which the one or more downlink OFDMA data units were transmitted, and determines whether each of the one or more sub-channels on which the one or more downlink OFDMA data units were transmitted is busy. The first communication device generates an uplink OFDM data unit for each sub-channel determined to be not busy, and transmits each of the uplink OFDM data units to the second communication device via the corresponding sub-channel.

What is claimed is: 
     
         1 . A method for simultaneous communication with multiple communication devices in a wireless local area network, the method comprising:
 receiving, at a first communication device, one or more downlink orthogonal frequency division multiplexing (OFDM) data units transmitted by a second communication device via one or more respective sub-channels of an OFDM communication channel;   identifying, by the first communication device, the one or more sub-channels of the OFDM communication channel on which the one or more downlink OFDMA data units were transmitted;   determining, by the first communication device, whether each of the one or more sub-channels on which the one or more downlink OFDMA data units were transmitted is busy;   generating, by the first communication device, an uplink OFDM data unit for each sub-channel determined to be not busy; and   transmitting each of the uplink OFDM data units to the second communication device via the corresponding sub-channel.   
     
     
         2 . The method of  claim 1 , wherein the one or more downlink OFDM data units comprise synchronization frames and the one or more uplink OFDM data units comprise one or more aggregate media access control protocol data units (A-MPDU). 
     
     
         3 . The method of  claim 2 , further comprising receiving, at the first communication device via the sub-channels on which the one or more uplink OFDM data units were transmitted, a block acknowledgment that indicates receipt of the one or more A-MPDUs by the second communication device. 
     
     
         4 . The method of  claim 3 , further comprising receiving, at the first communication device, a broadcast block acknowledgment having i) a first device identifier corresponding to the first communication device, ii) one or more other device identifiers corresponding to one or more other communication devices, iii) one or more bitmaps that indicate whether each of the one or more A-MPDUs was successfully received by the second communication device, and iv) one or more other bitmaps corresponding to the one or more other communication devices. 
     
     
         5 . The method of  claim 2 , wherein:
 the synchronization frame includes a quality of service indicator, and   generating the one or more uplink OFDM data units comprises generating the one or more A-MPDU to include only MPDUs having the corresponding quality of service indicator.   
     
     
         6 . The method of  claim 1 , wherein the one or more downlink OFDM data units comprise one or more A-MPDUs and the one or more uplink OFDM data units comprise one or more acknowledgments to the one or more A-MPDU. 
     
     
         7 . The method of  claim 1 , wherein the one or more uplink OFDM data units are a portion of an orthogonal frequency division multiple access (OFDMA) data unit. 
     
     
         8 . The method of  claim 1 , wherein:
 the OFDM communication channel comprises a MIMO communication channel and the one or more sub-channels comprise one or more space time streams of the MIMO communication channel; and   receiving the one or more downlink OFDM data units comprises receiving the one or more downlink OFDM data unit via the corresponding space time stream.   
     
     
         9 . An apparatus, comprising:
 a network interface device associated with a first communication device, the network interface device having one or more integrated circuit devices configured to
 receive, from a second communication device, one or more downlink orthogonal frequency division multiplexing (OFDM) data units transmitted by a second communication device via one or more respective sub-channels of an OFDM communication channel, 
 identify the one or more sub-channels of the OFDM communication channel on which the one or more downlink OFDMA data units were transmitted, 
 determine whether each of the one or more sub-channels on which the one or more downlink OFDMA data units were transmitted is busy, 
 generate an uplink OFDM data unit for each sub-channel determined to be not busy, and 
 transmit each of the uplink OFDM data units to the second communication device via the corresponding sub-channel. 
   
     
     
         10 . The apparatus of  claim 9 , wherein the one or more downlink OFDM data units comprise one or more synchronization frames and the one or more uplink OFDM data units comprise one or more aggregate media access control protocol data units (A-MPDU). 
     
     
         11 . The apparatus of  claim 10 , wherein the one or more integrated circuit devices are configured to receive, via the sub-channels on which the one or more uplink OFDM data units were transmitted, a block acknowledgment that indicates receipt of the one or more A-MPDUs by the second communication device. 
     
     
         12 . The apparatus of  claim 11 , wherein the one or more integrated circuit devices are configured to receive a broadcast block acknowledgment having i) a first device identifier corresponding to the first communication device, ii) one or more other device identifiers corresponding to one or more other communication devices, iii) one or more bitmaps that indicate whether each of the one or more A-MPDUs was successfully received by the second communication device, and iv) one or more other bitmaps corresponding to the one or more other communication devices. 
     
     
         13 . The apparatus of  claim 10 , wherein:
 the synchronization frame includes a quality of service indicator, and   the one or more integrated circuit devices are configured to generate the one or more uplink OFDM data units comprises generating the one or more A-MPDU to include only MPDUs having the corresponding quality of service indicator.   
     
     
         14 . The apparatus of  claim 9 , wherein the one or more downlink OFDM data units comprise one or more A-MPDUs and the one or more uplink OFDM data units comprise one or more acknowledgments to the one or more A-MPDU. 
     
     
         15 . The apparatus of  claim 9 , wherein the one or more uplink OFDM data units are a portion of an orthogonal frequency division multiple access (OFDMA) data unit. 
     
     
         16 . The apparatus of  claim 9 , wherein:
 the OFDM communication channel comprises a MIMO communication channel and the one or more sub-channels comprise one or more space time streams of the MIMO communication channel; and   the one or more integrated circuit devices are configured to receive the one or more downlink OFDM data unit via the corresponding space time stream.   
     
     
         17 . The apparatus of  claim 9 , wherein the network interface device comprises one or more transceivers. 
     
     
         18 . The apparatus of  claim 17 , further comprising:
 one or more antennas coupled to the one or more transceivers.