Media access control apparatus and method for guaranteeing quality of service in wireless lan

Abstract

A media access control (MAC) apparatus and corresponding methods for guaranteeing quality-of-service in a wireless local area network (LAN) are presented. The MAC method includes extracting, performing, determining, a first transmitting step, and a second transmitting step. The extracting includes extracting a user priority from a frame received from an upper layer and separately storing a voice frame and a non-voice frame according to an access category (AC). The performing includes independently performing backoff operations for the voice frame and the non-voice frame. The determining includes determining whether the backoff operations for the voice frame and the non-voice frame have simultaneously ended. The first transmitting includes transmitting the voice frame having a higher priority first and performing the backoff operation for the non-voice frame if the backoff operations have simultaneously ended. The second transmitting includes transmitting a frame whose backoff operation ends if the backoff operations have not simultaneously ended.

1 . A media access control (MAC) method in a MAC apparatus comprising:
 independently performing a backoff for a voice frame and a non-voice frame;   transmitting the voice frame with a higher priority and invoking the backoff for the non-voice frame when the backoff for the voice frame and the non-voice frame simultaneously end; and   transmitting a frame whose backoff ends first when the backoff for the voice frame and the non-voice frame do not simultaneously end.   
     
     
         2 . The method of  claim 1 , further comprising:
 receiving a frame from an upper layer comprising the voice frame and the non-voice frame;   detecting a busy channel;   waiting during a distribution inter-frame space (DIFS) time; and   performing the backoff when the channel is idle after the DIFS time lapses, wherein the backoff operation is performed to obtain a channel access right.   
     
     
         3 . The method of  claim 1 , wherein Arbitration inter-frame space (AIFS) of the voice frame is shorter than the one of the non-voice frame. 
     
     
         4 . The method of  claim 3 , wherein ACK policy information is included in a QoS control field of a header in the frame. 
     
     
         5 . The method of  claim 2 , further comprising:
 transmitting the frame without the backoff when the transmission queue is empty and the channel is idle after the DIFS lapses.   
     
     
         6 . The method of  claim 1 , further comprising:
 stopping the backoff when the channel becomes busy during the backoff.   
     
     
         7 . The method of  claim 2 , further comprising:
 performing backoff from a last backoff count when the channel is continuously idle during the DIFS time.   
     
     
         8 . A media access control (MAC) apparatus comprising:
 a first transmission queue configured to transmit a voice frame;   a second transmission queue configured to transmit a non-voice frame; and   a controller configured to independently perform a backoff for the voice frame and the non-voice frame, transmit the voice frame with a higher priority and invoking the backoff for the non-voice frame when the backoff for the voice frame and the non-voice frame simultaneously end, and transmit a frame whose backoff ends first when the backoff for the voice frame and the non-voice frame do not simultaneously end.   
     
     
         9 . The apparatus of  claim 8 , wherein the controller is further configured to
 receive a frame from an upper layer comprising the voice frame and the non-voice frame,   detect a busy channel,   wait during a distribution inter-frame space (DIFS) time, and   perform the backoff when the channel is idle after the DIFS time lapses, wherein the backoff operation is performed to obtain a channel access right.   
     
     
         10 . The apparatus of  claim 9 , wherein the controller is further configured to transmit the frame without the backoff when the transmission queue is empty and the channel is idle after the DIFS lapses. 
     
     
         11 . The apparatus of  claim 8 , wherein the controller is further configured to stop the backoff when the channel becomes busy during the backoff. 
     
     
         12 . The apparatus of  claim 9 , wherein the controller is further configured to perform backoff from a last backoff count when the channel is continuously idle during the DIFS time. 
     
     
         13 . A media access control method in a MAC apparatus, comprising:
 independently performing backoff in transmit queues;   checking whether the independent backoff simultaneously end in the transmit queues;   transmitting a frame having a higher priority and invoking backoff operation for a frame having a lower priority when at least two of the backoff simultaneously end; and   transmitting a frame whose backoff ends first when the backoff operations do not simultaneously end.   
     
     
         14 . The method of  claim 13 , wherein the frame comprises a header having an acknowledgement (ACK) policy information field representing whether a receiver should transmit an ACK response. 
     
     
         15 . The method of  claim 14 , wherein a QoS Control field of the header includes the ACK policy information. 
     
     
         16 . A media access control (MAC) apparatus, comprising:
 a frame handler configured to classify frames into at least two groups based on the user priority, and configured to store the frames in at least two transmit queues corresponding to the groups; and   a controller configured to
 independently perform backoff operations in the transmit queues, 
 check whether or not the independent backoff operations simultaneously end, 
 transmit a frame having a higher priority and invoking backoff operation for a frame having a lower priority when at least two of the backoff operations simultaneously end, and 
 transmit a frame whose backoff operation ends first when the backoff operations do not simultaneously end. 
   
     
     
         17 . The apparatus of  claim 16 , wherein the frame comprises a header having an acknowledgement (ACK) policy information field representing whether a receiver should transmit an ACK response. 
     
     
         18 . The apparatus of  claim 17 , wherein a QoS Control field of the header includes the ACK policy information. 
     
     
         19 . A computer program embodied on a non-transitory computer readable medium, the computer program being configured to control a processor to perform the method of  claim 1 . 
     
     
         20 . A computer program embodied on a non-transitory computer readable medium, the computer program being configured to control a processor to perform the method of  claim 13 .