Method and apparatus for transmitting control frame to hidden node in wireless LAN

Abstract

A method and apparatus informs nodes included in a wireless local area network (LAN) of how to avoid access collision in a wireless LAN. A wireless LAN access point or an independent basic service set (IBSS) control station receives a Contention-Free-End (CF-End) frame, compares a basic service set ID (BSSID) of the received CF-End frame of the access point or the IBSS, and rebroadcasts the received CF-End frame if the comparison result indicates that the two BSSIDs coincide with each other. Thus, all stations included in one BSS can receive the same time information for controlling medium access.

What is claimed is: 
     
       1. A method of delivering transmitting a control Contention Free-End (CF-End) frame for a device which communicates through a wireless local area network (LAN), the method comprising steps performed by a first station of:
 receiving a control frame including time information for controlling medium access and recipient address information; 
 checking recipient address information a Basic Service Set ID (BSSID) included in a CF-End frame, the CF-End frame including a duration field of a MAC header set to zero; and 
 broadcasting the received control frame in a selective manner based on a checking result, to a second station, the CF-End frame directly in response to determining the Basic Service Set ID (BSSID) in the CF-End frame matches a BSSID of a Basic Service Set (BSS) where said first station is included, wherein the step of broadcasting the CF-End frame to said second station comprises the step of broadcasting the CF-End frame when a Short Inter Frame Space (SIFS) elapses after the CF-End frame was received, and 
 wherein, in the control frame, a duration field of a MAC (medium access control) header has a value of 0, 
 wherein the control frame is a Contention-Free-End (CF-End) frame, 
 wherein the broadcasting the received control frame comprises broadcasting the received CF-END frame if the checking result indicates that a basic service set ID (BSSID) recorded in the CF-End frame coincides with a BSSID of a BSS (basic service set), and 
 wherein the broadcasting the received control frame further comprises broadcasting the received CF-END frame when a short inter-frame space (SIFS) elapses after the CF-End frame is received wherein a Network Allocation Vector (NAV) of said second station is reset upon a receipt of the CF-End frame. 
 
     
     
       2. The method of  claim 1 , wherein the said wireless LAN is an infrastructure BSS, and the device said first station is an access point of the said infrastructure BSS. 
     
     
       3. A non-transitory computer-readable medium having embodied thereon a computer program for executing the method of  claim 2 . 
     
     
       4. The method of  claim 1 , wherein the said wireless LAN is an IBSS (independent BSS (IBSS), and the device said first station is an IBSS control station that sends configured to send a beacon frame. 
     
     
       5. A non-transitory computer-readable medium having embodied thereon a computer program for executing the method of  claim 4 . 
     
     
       6. A non-transitory computer-readable medium having embodied thereon a computer program for executing the method of  claim 1 . 
     
     
       7. An apparatus for delivering transmitting a control Contention Free-End (CF-End) frame received through a wireless LAN, the apparatus comprising:
 a recipient address information checking unit which checks recipient address information receiver configured to check a Basic Service Set ID (BSSID) included in the control a CF-End frame when the control frame including time information for medium access is received, the CF-End frame including a duration field of a MAC header set to zero; and 
 a resending unit which broadcasts the received control transmitter configured to broadcast the CF-End frame in a selective manner based on the checking result, directly in response to determining the Basic Service Set ID in the CF-End frame matches a BSSID of a Basic Service Set (BSS) where the apparatus is included, wherein said transmitter is configured to broadcast the CF-End frame when a Short Inter Frame Space (SIFS) elapses after the CF-End frame was received, and 
 wherein, in the control frame, a duration field of a MAC header has a value of 0, wherein the control frame is a CF-End frame, 
 wherein, the resending unit broadcasts the CF-End frame if the checking result indicates that a recipient address recorded in the CF-End frame is a broadcast address, and a BSSID recorded in the CF-End frame coincides with a BSSID of a BSS (basic service set), and 
 wherein, the resending unit broadcasts the received CF-End frame when a SIFS elapses after the CF-End frame wherein a Network Allocation Vector (NAV) of a recipient of the CF-End frame is reset upon a receipt of the CF-End frame. 
 
     
     
       8. An access point comprising the apparatus of  claim 7 . 
     
     
       9. A wireless LAN station which comprises the apparatus of  claim 7 , and operates is configured to operate the apparatus only when the wireless LAN station operates as an IBSS independent BSS control station that sends configured to send a beacon frame in the independent BSS. 
     
     
       10. The method of claim 1, wherein the CF-End frame is transmitted by said first station to indicate a completion of a transmission opportunity of said first station. 
     
     
       11. The method of claim 10, wherein another station that receives the CF-End frame resets a Network Allocation Vector (NAV) so said another station is operable to contend for medium access. 
     
     
       12. The apparatus of claim 7, wherein said apparatus is configured to transmit the CF-End frame to indicate a completion of a transmission opportunity. 
     
     
       13. The apparatus of claim 12, wherein another station that is configured to receive the CF-End frame is configured to reset a Network Allocation Vector (NAV) so said another station is operable to contend for medium access.