System and method of frame scheduling for QoS-driven wireless local area network (WLAN)

• US 6,850,981 B1
• Filed: 07/14/2000
• Issued: 02/01/2005
• Est. Priority Date: 07/14/2000
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Ho, Jin-Meng, Lin, Wei
• Primary Examiner(s): Barot, Bharat
• Assistant Examiner(s): Tran, Philip B.
• Application Number:
  US09/617,493
• Time in Patent Office: 1,663 Days
• Field of Search: 709/232, 709227-228, 709/238, 709223-224, 370/338, 370/432, 370/445, 370/465
• US Class Current: 709/227
• CPC Class Codes: H04L 47/215 using token-bucket
• CPC Class Codes: H04L 47/2408 for supporting different services, e.g. a differentiated services [DiffServ] type of service
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/31 by tagging of packets, e.g. using discard eligibility [DE] bits
• CPC Class Codes: H04L 47/35 by embedding flow control information in regular packets, e.g. piggybacking
• CPC Class Codes: H04L 47/70 Admission control; Resource allocation
• CPC Class Codes: H04L 47/724 at intermediate nodes, e.g. resource reservation protocol [RSVP]
• CPC Class Codes: H04L 47/745 Reaction in network
• CPC Class Codes: H04L 47/801 Real time traffic
• CPC Class Codes: H04L 47/805 QOS or priority aware
• CPC Class Codes: H04L 47/824 Applicable to portable or mobile terminals
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 72/543 based on requested quality, e.g. QoS
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/02 Data link layer protocols
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A frame scheduling entity (FSE) for a station having a point coordinator (PC) in a basic service set (BSS) in a wireless local area network (WLAN) is disclosed. The FSE is located at a medium access control (MAC) sublayer of the station, and includes a scheduling table and a scheduling element. The scheduling table is logically located at a medium access control (MAC) sublayer of the station, and contains at least one entry corresponding to a session admitted to transmit traffic over the wireless network. The entry contains a virtual stream (VS) identifier (VSID), a QoS parameter set, and a data size that are each associated with the session. The scheduling table also includes a permanent entry containing a null QoS parameter set and corresponding to best-effort (asynchronous) traffic from the PC to a non-PC station associated with the PC. The scheduling element schedules transmission of a data frame for a session between peer logical link control (LLC) sublayer entities of the BSS based on the information contained in the entry for the session. The data frame scheduled by the scheduling element is labeled by the VSID contained in the entry.

Claims

1. A frame scheduling entity (FSE) for a station having a point coordinator (PC) in a basic service set (BSS) in a wireless local area network, the FSE being located at a medium access control (MAC) sublayer of the station, comprising:

a scheduling table logically located at said MAC sublayer of the station, the scheduling table containing at least one entry corresponding to a session admitted to transmit traffic over the wireless network, the entry containing a virtual stream (VS) identifier (VSID), an in-band quality of service (QoS) parameter set, and a data size that are each associated with the session; and

a scheduling element for scheduling transmission of a data frame for a session between logical link control (LLC) sublayer entities of said station and LLC sublayer entities of peer stations of the BSS based on the information contained in the entry for the session, the data frame being labeled by the VSID contained in the entry.

2. The FSE according to claim 1, wherein the VSID is a result of a classifiable action and is associated with one of a virtual down-stream (VDS), a virtual up-stream (VUS), and a virtual side-stream (VSS), a VDS being a VS for transmitting the traffic of a QoS session from the PC to at least one non-PC station in the BSS, a VUS being a VS for transmitting the traffic of a QoS session from a non-PC station to the PC in the BSS, and a VSS being a VS for transmitting the traffic of a QoS session from a non-PC station to at least another non-PC station in the BSS;

and

wherein the QoS parameter set contains at least one QoS parameter value and is used for transmitting the data frame of the corresponding QoS session.

3. The FSE according to claim 1, wherein the VSID is a result of an unclassifiable action and is associated with best-effort (asynchronous) traffic;

wherein the QoS parameter set is a null set, and

wherein a best effort is used for transmitting the data frame.

4. The FSE according to claim 1, wherein the scheduling table includes a permanent entry containing a null QoS parameter set and corresponding to best-effort (asynchronous) traffic from the PC to a non-PC station associated with the PC.

5. The FSE according to claim 1, wherein the scheduling table includes an entry for each non-PC station that is associated with the PC, the entry containing a null QoS parameter set and corresponding to best-effort (asynchronous) traffic from a selected non-PC station.

6. The FSE according to claim 5, wherein the selected non-PC station includes a local FSE logically located at a MAC sublayer of the non-PC station.

7. The FSE according to claim 1, wherein the scheduling table includes an entry for each virtual stream (VS) established in the BSS.

8. The FSE according to claim 1, wherein the FSE schedules transfer of data frames for down-stream, up-stream, and side-stream sessions between peer LLC sublayer entities in the BSS during a contention-free period (CFP) of a superframe, the down-stream session being transferred from the PC to at least one non-PC station in the BSS, the up-stream session being transferred from a non-PC station to the PC in the BSS, and the side-stream session being transferred from a non-PC station to at least one other non-PC station in the BSS.

9. The FSE according to claim 1, wherein the QoS parameter set relates to at least one of an acknowledgment policy, a flow type, a priority level, a privacy level, a delay bound, a jitter bound, a minimum data rate, a mean data rate, and a maximum data burst, the flow type being one of a continuous flow type and a discontinuous flow type, the mean data rate being a token rate of a token bucket, and the maximum data burst being a bucket size of the token bucket.

10. The FSE according to claim 1, wherein the data size for a down-stream session is determined by the size of the data classified to a virtual down-stream (VDS) for the session, and wherein the data size in the entry for best-effort traffic from the PC is determined by the size of the unclassifiable data waiting at the PC for transmission.

11. The FSE according to claim 1, wherein the data size for an up-stream session associated with a continuous flow type is determined by the mean data rate and the maximum data burst contained in the QoS parameter set for the session,

wherein the data size for an up-stream session associated with a discontinuous flow type is determined by data size information provided by a transmitting station of the session through one of a reservation request and a piggyback,

wherein the data size for an up-stream session is further updated by data size information piggybacked in a data frame transmitted from the session, and

wherein the data size in the entry for best-effort traffic from a non-PC station to the PC station is determined by data size information provided by the non-PC station through one of a reservation request and a piggyback.

12. The FSE according to claim 1, wherein the data size for a side-stream session associated with a continuous flow type is determined by the mean data rate and the maximum data burst contained in the QoS parameter set for the session,

wherein the data size for a side-stream session associated with a discontinuous flow type is determined by data size information provided by a transmitting station of the session through one of a reservation request and a piggyback,

wherein the data size for a side-stream session is further updated by a data size information piggybacked in data frame transmitted from the session, and

wherein the data size in the entry for best-effort traffic from a non-PC station to at least one non-PC station in the BSS is determined by data size information provided by the non-PC station through one of a reservation request and a piggyback.

13. The FSE according to claim 1, wherein the FSE schedules a transmission opportunity (TO) for each entry in the scheduling table in a contention-free period (CFP) of a superframe based on the QoS parameter set and the data size in the entry.

14. The FSE according to claim 13, wherein the QoS parameter set includes a mean data rate and a maximum data burst, and

wherein the TO for each entry is further based on a token bucket mechanism associated with the mean data rate and the maximum data burst contained in the QoS parameter set of the entry.

15. The FSE according to claim 14, wherein the TO includes a predetermined start time and a predetermined maximum duration time.

16. The FSE according to claim 15, wherein the BSS includes at least one non-PC station associated with the PC station, the at least one non-PC station including a local FSE logically located at a MAC sublayer of the non-PC station, and

wherein when a non-PC station is given a TO by the FSE of the PC station, the local FSE of the non-PC station schedules transfer of data frames buffered at the non-PC station for transmission based on the TO and the QoS parameter sets associated with the data frames buffered at the non-PC station.

17. The FSE according to claim 1, wherein the session is a one-directional traffic of one of a voice call, a data call, a video call, and a multimedia call.

18. The FSE according to claim 1, wherein the wireless network is a wireless local area network (WLAN).

19. A method for scheduling transmission of a data frame in a basic service set (BSS) in a wireless network, the method comprising steps of:

forming a scheduling table logically located at a medium access control (MAC) sublayer of a station having a point coordinator (PC), the scheduling table containing at least one entry corresponding to a session admitted to transmit traffic over the wireless network, the entry containing a virtual stream (VS) identifier (VSID), an in-band quality of service (QoS) parameter set, and a data size that are each associated with the session; and

scheduling transmission of a data frame for a session between logical link control (LLC) sublayer entities of said station and LLC sublayer entities of peer stations of the BSS based on the information contained in the entry for the session, the data frame being labeld by the VSID contained in the entry.

20. The method according to claim 19,

wherein the VSID is an outcome of a classifiable action and is associated with one of a virtual down-stream (VDS), a virtual up-stream (VUS), and a virtual side-stream (VSS), a VDS being a VS for transmitting the traffic of a QoS session from the PC to at least one non-PC station in the BSS, a VUS being a VS for transmitting the traffic of a QoS session from a non-PC station to the PC in the BSS, and a VSS being a VS for transmitting the traffic of a QoS session from a non-PC station to at least another non-PC station in the BSS, and

wherein the QoS parameter set contains at least one QoS parameter value and is used for transmitting the data frame of the corresponding QoS session.

21. The method according to claim 19, wherein the VSID is an outcome of an unclassifiable action and is associated with best-effort (asynchronous) traffic,

wherein the QoS parameter set is a null set, and

wherein the step of scheduling schedules transmission of the data frame is taken on a best effort basis.

22. The method according to claim 19, wherein the scheduling table includes a permanent entry containing a null QoS parameter set and corresponding to best-effort (asynchronous) traffic from the PC to a non-PC station associated with the PC.

23. The method according to claim 19, wherein the scheduling table includes an entry for each non-PC station that is associated with the PC, the entry containing a null QoS parameter set and corresponding to best-effort (asynchronous) traffic from a selected non-PC station.

24. The method according to claim 23, wherein the selected non-PC station includes a local FSE logically located at a MAC sublayer of the non-PC station.

25. The method according to claim 19, wherein the scheduling table includes an entry for each virtual stream (VS) established in the BSS.

26. The method according to claim 19, wherein the step of scheduling schedules transfer of data frames for down-stream, up-stream, and side-stream sessions between peer LLC sublayer entities in the BSS during a contention-free period (CFP) of a superframe, the down-stream session being transferred from the PC to at least one non-PC station in the BSS, the upstream session being transferred from a non-PC station to the PC in the BSS, and the side-stream session being transferred from a non-PC station to at least one other non-PC station in the BSS.

27. The method according to claim 19, wherein the QoS parameter set relates to at least one of an acknowledgment policy, a flow type, a priority level, a privacy level, a delay bound, a jitter bound, a minimum data rate, a mean data rate, and a maximum data burst, the flow type being one of a continuous flow type and a discontinuous flow type, the mean data rate being a token rate of a token bucket, and the maximum data burst being a bucket size of the token bucket.

28. The method according to claim 19, further comprising steps of determining the data size for a down-stream session based on the size of the data classified to a virtual down-stream (VDS) for the session, and

determining a data size for unclassifiable data waiting at the PC for transmission based on the data size in the entry maintained for best-effort traffic from the PC.

29. The method according to claim 19, further comprising steps of:

determining the data size for an up-stream session associated with a continuous flow type based on the mean data rate and the maximum data burst contained in the QoS parameter set for the up-stream session;

determining the data size for an up-stream session associated with a discontinuous flow type based on data size information provided by a transmitting station of the session through one of a reservation request and a piggyback;

updating the data size for an upstream session based on data size information piggybacked in a data frame transmitted from the session; and

updating the data size in the entry for best-effort traffic from a non-PC station to the PC station based on data size information provided by the non-PC station through one of a reservation request and a piggyback.

30. The method according to claim 19, further comprising steps of:

determining the data size for a side-stream session associated with a continuous flow type based on the mean data rate and the maximum data burst contained in the QoS parameter set for the session;

determining the data size for a side-stream session associated with a discontinuous flow type based on data size information provided by a transmitting station of the session through one of a reservation request and a piggyback;

updating the data size for a side-stream session based on data size information piggybacked in a data frame transmitted from the session, and

determining the data size in the entry for best-effort traffic from a non-PC station to at least one non-PC station in the BSS based on data size information provided by the non-PC station through one of a reservation request and a piggyback.

31. The method according to claim 19, further comprising a step of scheduling a transmission opportunity (TO) for each entry in the scheduling table in a contention-free period (CFP) of a superframe based on the QoS parameter set and the data size in the entry.

32. The method according to claim 31, wherein the QoS parameter set includes a mean data rate and a maximum data burst, and

wherein the TO for each entry is further based on a token bucket mechanism associated with the mean data rate and the maximum data burst contained in the QoS parameter set of the entry.

33. The method according to claim 32, wherein the TO includes a predetermined start time and a predetermined maximum duration time.

34. The method according to claim 33, wherein the BSS includes at least one non-PC station associated with the PC station, the at least one non-PC station including a local FSE,

the method further comprising a step of scheduling, at the local FSE of the non-PC station, transfer of data frames buffered at the non-PC station for transmission based on the TO and the QoS parameter sets associated with the data flames buffered at the non-PC station when the non-PC station is given a TO.

35. The method according to claim 19, wherein the session is a one-directional traffic of one of a voice call, a data call, a video call, and a multimedia call.

36. The method according to claim 19, wherein the wireless network is a wireless local area network (WLAN).