Method and apparatus performing express forwarding bypass for time-critical frames
View Patent ↗A method, apparatus and computer program product for the express forwarding bypass are presented. A timer (NAV) is maintained at each respective node of a wireless LAN, the timer (NAV) set to a corresponding time period during which the respective node must refrain from transmitting on a channel. The first node of said plurality of nodes has a time-critical (TC) frame. The first node detects a frame to be express-forwarded by a second node. The first node decrements the duration field by a first predetermined time increment (DT 0 ) before setting its NAV. The first node attempts transmission of the TC frame or back off countdown when the NAV of said first node expires.
1. A method comprising:
maintaining at each respective node of a plurality of nodes of a wireless Local Area Network (LAN), a timer (NAV) set to a corresponding time period during which the respective node must refrain from transmitting on a channel, and wherein a first node of said plurality of nodes has a time-critical (TC) frame;
detecting by the first node of said plurality of nodes, a frame to be express-forwarded by a second node;
decrementing by said first node a duration field by a first predetermined time increment (DT 0 ) before setting its NAV in response to said detecting a frame to be express forwarded;
setting said NAV to a value of said duration field; and
wherein said first node attempts transmission of said TC frame when said NAV of said first node expires, thereby providing express forwarding bypass since said NAV is set to a lower value then it would otherwise be.
2. The method of claim 1 wherein said first predetermined time increment is at least one time slot long.
3. The method of claim 1 wherein said first node performs Clear Channel Assessment (CCA) before attempting transmission.
4. The method of claim 1 wherein when the channel for transmission is busy, said first node backs off from a short contention window size for a Access Category (AC).
5. The method of claim 1 wherein when a collision occurs when said first node attempts transmission of said time-critical frame when said NAV of said first node expires, a random backoff period is observed and retransmission attempted when said backoff period expires.
6. The method of claim 1 further comprising sensing, by said second node with the express-forwarded frame, that the channel is busy when the TC frame is transmitted by said first node.
7. The method of claim 6 wherein in response to said sensing the channel is busy, said second node backs off from transmitting using a random delay from a short contention window.
8. The method of claim 1 further comprising decrementing, by a third node which is the intended recipient of an express-forwarded frame, a duration field by a second predetermined time increment (DTI) before setting its NAV.
9. The method of claim 8 further comprising wherein said third node attempts forwarding of said express-forwarded frame when said NAV of said third node expires.
10. The method of claim 8 wherein said DT 1 is shorter than said DT 0 by at least one time slot.
11. A non-transitory computer readable medium having computer readable code thereon for providing express forwarding bypass for time-critical frames, the medium comprising:
instructions for maintaining at each respective node of a plurality of nodes of a wireless Local Area Network (LAN), a timer (NAV) set to a corresponding time period during which the respective node must refrain from transmitting on a channel, and wherein a first node of said plurality of nodes has a time-critical (TC) frame;
instructions for detecting by the first node of said plurality of nodes, a frame to be express-forwarded by a second node;
instructions for decrementing by said first node a duration field by a first predetermined time increment (DT 0 ) before setting its NAV in response to said detecting a frame to be express forwarded;
setting said NAV to a value of said duration field; and
wherein said first node attempts transmission of said TC frame when said NAV of said first node expires, thereby providing express forwarding bypass since said NAV is set to a lower value then it would otherwise be.
12. The computer readable medium of claim 11 further comprising instructions wherein said first predetermined time increment is at least one time slot long.
13. The computer readable medium of claim 11 further comprising instructions wherein said first node performs Clear Channel Assessment (CCA) before attempting transmission.
14. The computer readable medium of claim 11 further comprising instructions wherein when the channel for transmission is busy, said first node backs off from a short contention window size for a particular Access Category (AC).
15. The computer readable medium of claim 11 further comprising instructions wherein when a collision occurs when said first node attempts transmission of said time-critical frame when said NAV of said first node expires, a random backoff period is observed and retransmission attempted when said backoff period expires.
16. The computer readable medium of claim 11 further comprising instructions for sensing, by said second node with the express-forwarded frame, that the channel is busy when the TC frame is transmitted by said first node.
17. The computer readable medium of claim 16 further comprising instructions wherein in response to said sensing the channel is busy, said second node backs off from transmitting using a random delay from a short contention window.
18. The computer readable medium of claim 11 further comprising instructions for decrementing, by a third node which is the intended recipient of an express-forwarded frame, a duration field by a second predetermined time increment (DTI) before setting its NAV.
19. The computer readable medium of claim 18 further comprising instructions wherein said third node attempts forwarding of said express-forwarded frame when said NAV of said third node expires.
20. The computer readable medium of claim 18 wherein said DT 1 is shorter than said DT 0 by at least one time slot.
21. A computer system comprising:
a memory;
a processor;
a communications interface;
an interconnection mechanism coupling the memory, the processor and the communications interface; and
wherein the memory is encoded with an express forwarding bypass application that when performed on the processor, provides an express forwarding bypass process for processing information, the express forwarding bypass process causing the computer system to be capable of performing the operations of: maintaining at each respective node of a plurality of nodes of a wireless Local Area Network (LAN), a timer (NAV) set to a corresponding time period during which the respective node must refrain from transmitting on a channel, and wherein a first node of said plurality of nodes has a time-critical (TC) frame;
detecting by the first node of said plurality of nodes, a frame to be express-forwarded by a second node;
decrementing by said first node a duration field by a first predetermined time increment (DT 0 ) before setting its NAV in response to said detecting a frame to be express forwarded;
setting said NAV to a value of said duration field; and
wherein said first node attempts transmission of said TC frame or back off countdown when said NAV of said first node expires, thereby providing express forwarding bypass since said NAV is set to a lower value then it would otherwise be.