802.11 restricted access windows

• US 9,204,371 B2
• Filed: 11/19/2012
• Issued: 12/01/2015
• Est. Priority Date: 11/23/2011
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Liu, Yong
• Primary Examiner(s): Vu, Huy D
• Assistant Examiner(s): HALL, TEISHA DANEA
• Application Number:
  US13/680,876
• Publication Number:
  US 20130128798A1
• Time in Patent Office: 1,107 Days
• Field of Search: 370/336, 370/348
• US Class Current: 1/1
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 74/06 using polling
• CPC Class Codes: H04W 74/0875 with assigned priorities based access

Abstract

A method of operating an access point includes defining a restricted access window during which stations that belong to a same infrastructure basic service set as the access point are not allowed to transmit data frames. The method further includes generating a beacon announcing the restricted access window, and transmitting the beacon to the stations that belong to the same infrastructure basic service set as the access point. The method also includes, during the restricted access window, receiving a poll frame from a first station of the stations that belong to the same infrastructure basic service set as the access point. The method further includes, subsequent to the poll frame, transmitting a data frame to the first station.

Claims

1. An access point comprising:

a restricted access window module configured to define a restricted access window during which stations that belong to a same infrastructure basic service set as the access point are not allowed to transmit data frames;

a beacon creation module configured to generate a beacon announcing the restricted access window, wherein the restricted access window is contained within a following beacon interval;

a transmitter module configured to transmit the beacon to the stations that belong to the same infrastructure basic service set as the access point, wherein the following beacon interval begins upon transmission of the beacon and ends upon transmission of a second beacon, wherein the transmitter module is configured to transmit the second beacon subsequent to the beacon without transmitting any intervening beacons;

a downlink tracking module configured to, during the restricted access window, receive a poll frame from a first station of the stations that belong to the same infrastructure basic service set as the access point; and

a data transmission module configured to, subsequent to the poll frame, transmit a data frame to the first station, wherein the beacon includes a delivery traffic indication map and includes an indication that the data frame is queued for transmission to the first station,

wherein during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a first value of a transmission characteristic, and

wherein during a second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a second value of the transmission characteristic.

2. The access point of claim 1, wherein:

the beacon creation module is configured to transmit, at a periodic interval, beacons including the delivery traffic indication map,

an active polling station is configured to wake up at intervals greater than the periodic interval, and

the access point is configured to allow the active polling station to transmit data frames during the restricted access window.

3. The access point of claim 1, wherein the restricted access window begins at a conclusion of transmission of the beacon.

4. The access point of claim 1, wherein:

the data transmission module is configured to selectively transmit at least one of multicast data and broadcast data upon conclusion of transmission of the beacon, and

the restricted access window begins upon conclusion of the transmission of the at least one of the multicast data and the broadcast data.

5. The access point of claim 1, wherein the beacon indicates an ending time of the restricted access window.

14. The access point of claim 1, wherein:

the restricted access window module is configured to define the second restricted access window to be subsequent to the restricted access window but prior to the second beacon; and

the transmitter module is configured to, subsequent to transmitting the beacon, transmit a reservation frame to announce the second restricted access window.

15. The access point of claim 14, wherein the transmitter module is configured to transmit the reservation frame upon conclusion of the restricted access window.

16. The access point of claim 15, wherein the transmitter module is configured to transmit the reservation frame at a beginning of the second restricted access window.

17. The access point of claim 1, further comprising an uplink tracking module configured to, during the restricted access window, (i) receive an uplink frame from a second station of the stations that belong to the same infrastructure basic service set as the access point and (ii) selectively respond to the second station with an acknowledgement, wherein the uplink frame indicates that the second station has a second data frame queued for transmission to the access point.

18. The access point of claim 17, wherein the acknowledgement indicates to the second station that the second station is expected to transmit the second data frame to the access point subsequent to the restricted access window.

19. The access point of claim 1, wherein the data transmission module is configured to (i) respond to the poll frame with the data frame in response to the data frame being ready for transmission and (ii) respond to the poll frame with an acknowledgement frame in response to the data frame not being ready for transmission.

20. The access point of claim 19, further comprising a data fetch module configured to, in response to the data frame not being ready for transmission, retrieve the data frame from a queue, wherein the data transmission module is configured to transmit the data frame to the first station subsequent to the restricted access window.

21. The access point of claim 20, wherein the data transmission module is configured to transmit the data frame to the first station in response to receiving a trigger frame from the first station.

43. The access point of claim 1, wherein the transmission characteristic is one of maximum transmission duration limit and priority.

6. An access point comprising:

a restricted access window module configured to define a restricted access window during which stations that belong to a same infrastructure basic service set as the access point are not allowed to transmit data frames;

a beacon creation module configured to generate a beacon announcing the restricted access window, wherein the restricted access window is contained within a following beacon interval;

a transmitter module configured to transmit the beacon to the stations that belong to the same infrastructure basic service set as the access point, wherein the following beacon interval begins upon transmission of the beacon and ends upon transmission of a second beacon, wherein the transmitter module is configured to transmit the second beacon subsequent to the beacon without transmitting any intervening beacons;

a downlink tracking module configured to, during the restricted access window, receive a poll frame from a first station of the stations that belong to the same infrastructure basic service set as the access point; and

a data transmission module configured to, subsequent to the poll frame, transmit a data frame to the first station,

wherein the restricted access window module is configured to define a second restricted access window that is subsequent to the restricted access window but prior to the second beacon, and

wherein the beacon creation module is configured to generate the beacon announcing both the restricted access window and the second restricted access window.

7. The access point of claim 6, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit a first set of frame types;

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit a second set of frame types;

at least one frame type of the first set of frame types is not included in the second set of frame types; and

at least one frame type of the second set of frame types is not included in the first set of frame types.

8. The access point of claim 6, wherein:

during the restricted access window, a first set of the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit;

during the second restricted access window, a second set of the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit;

at least one station in the first set is not included in the second set; and

at least one station in the second set is not included in the first set.

9. The access point of claim 6, wherein:

during the restricted access window, a first set of stations types are permitted to transmit;

during the second restricted access window, a second set of station types are permitted to transmit;

at least one station type in the first set is not included in the second set; and

at least one station type in the second set is not included in the first set.

10. The access point of claim 6, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a first value of a transmission characteristic; and

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a second value of the transmission characteristic.

11. The access point of claim 10, wherein the transmission characteristic is one of maximum transmission duration limit and priority.

12. The access point of claim 6, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames using a first value of a medium access parameter; and

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames using a second value of the medium access parameter.

13. The access point of claim 12, wherein the medium access parameter is slot time.

22. A method of operating an access point, the method comprising:

defining a restricted access window during which stations that belong to a same infrastructure basic service set as the access point are not allowed to transmit data frames;

generating a beacon announcing the restricted access window, wherein the restricted access window is contained within a following beacon interval;

transmitting the beacon to the stations that belong to the same infrastructure basic service set as the access point, wherein the following beacon interval begins upon transmission of the beacon and ends upon transmission of a second beacon that is transmitted subsequent to the beacon without any intervening beacons;

during the restricted access window, receiving a poll frame from a first station of the stations that belong to the same infrastructure basic service set as the access point; and

subsequent to the poll frame, transmitting a data frame to the first station,

wherein the beacon includes a delivery traffic indication map and includes an indication that the data frame is queued for transmission to the first station,

wherein, during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a first value of a transmission characteristic, and

wherein, during a second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a second value of the transmission characteristic.

23. The method of claim 22, further comprising:

transmitting, at a periodic interval, beacons including the delivery traffic indication map, wherein an active polling station is configured to wake up at intervals greater than the periodic interval; and

permitting the active polling station to transmit data frames during the restricted access window.

24. The method of claim 22, wherein the restricted access window begins at a conclusion of transmission of the beacon.

25. The method of claim 22, further comprising:

selectively transmitting at least one of multicast data and broadcast data upon conclusion of transmission of the beacon,

wherein the restricted access window begins upon conclusion of the transmission of the at least one of the multicast data and the broadcast data.

26. The method of claim 22, wherein the beacon indicates an ending time of the restricted access window.

35. The method of claim 22, further comprising:

defining the second restricted access window to be subsequent to the restricted access window but prior to the second beacon;

subsequent to transmitting the beacon, transmitting a reservation frame to announce the second restricted access window; and

transmitting the second beacon.

36. The method of claim 35, further comprising transmitting the reservation frame upon conclusion of the restricted access window.

37. The method of claim 36, further comprising transmitting the reservation frame at a beginning of the second restricted access window.

38. The method of claim 22, further comprising during the restricted access window, (i) receiving an uplink frame from a second station of the stations that belong to the same infrastructure basic service set as the access point and (ii) selectively responding to the second station with an acknowledgement, wherein the uplink frame indicates that the second station has a second data frame queued for transmission to the access point.

39. The method of claim 38, wherein the acknowledgement indicates to the second station that the second station is expected to transmit the second data frame to the access point subsequent to the restricted access window.

40. The method of claim 22, further comprising responding to the poll frame with (i) the data frame in response to the data frame being ready for transmission and (ii) an acknowledgement frame in response to the data frame not being ready for transmission.

41. The method of claim 40, further comprising:

in response to the data frame not being ready for transmission, retrieving the data frame from a queue; and

transmitting the data frame to the first station subsequent to the restricted access window.

42. The method of claim 41, further comprising transmitting the data frame to the first station in response to receiving a trigger frame from the first station.

44. The method of claim 22, wherein the transmission characteristic is one of maximum transmission duration limit and priority.

27. A method of operating an access point, the method comprising:

defining a restricted access window during which stations that belong to a same infrastructure basic service set as the access point are not allowed to transmit data frames;

generating a beacon announcing the restricted access window, wherein the restricted access window is contained within a following beacon interval;

transmitting the beacon to the stations that belong to the same infrastructure basic service set as the access point, wherein the following beacon interval begins upon transmission of the beacon and ends upon transmission of a second beacon that is transmitted subsequent to the beacon without any intervening beacons;

during the restricted access window, receiving a poll frame from a first station of the stations that belong to the same infrastructure basic service set as the access point;

subsequent to the poll frame, transmitting a data frame to the first station;

defining a second restricted access window that is subsequent to the restricted access window but prior to the second beacon, wherein the beacon announces both the restricted access window and the second restricted access window; and

transmitting the second beacon.

28. The method of claim 27, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit a first set of frame types;

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit a second set of frame types;

at least one frame type of the first set of frame types is not included in the second set of frame types; and

at least one frame type of the second set of frame types is not included in the first set of frame types.

29. The method of claim 27, wherein:

during the restricted access window, only a first set of the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit;

during the second restricted access window, only a second set of the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit;

at least one station in the first set is not included in the second set; and

at least one station in the second set is not included in the first set.

30. The method of claim 27, wherein:

during the restricted access window, stations that belong to the same infrastructure basic service set as the access point, and are one of a first set of station types, are permitted to transmit;

during the second restricted access window, stations that belong to the same infrastructure basic service set as the access point, and are one of a second set of station types, are permitted to transmit;

at least one station type in the first set is not included in the second set; and

at least one station type in the second set is not included in the first set.

31. The method of claim 27, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a first value of a transmission characteristic; and

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames having a second value of the transmission characteristic.

32. The method of claim 31, wherein the transmission characteristic is one of maximum transmission duration limit and priority.

33. The method of claim 27, wherein:

during the restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames using a first value of a medium access parameter; and

during the second restricted access window, the stations that belong to the same infrastructure basic service set as the access point are permitted to transmit frames using a second value of the medium access parameter.

34. The method of claim 33, wherein the medium access parameter is slot time.