Method and system for channel time allocation and access control in wireless networks

• US 20070253391A1
• Filed: 04/17/2007
• Published: 11/01/2007
• Est. Priority Date: 04/20/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Singh, Harkirat, Shao, Huai-Rong, Ngo, Chiu
• Granted Patent: US 8,325,686 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02

Abstract

A channel time allocation and access control process for communication in wireless networks is provided. The channel time is divided into channel time blocks (CTBs), including one or more reserved CTBs and one or more unreserved CTBs. Schedules are implemented, wherein one or more periodic, equal-sized CTBs are reserved for isochronous streams. Dynamic CTB extension and truncation allow flexible channel time allocation.

Claims

1. A method of communicating information over one or more wireless channels in a network, comprising the steps of:

controlling channel access among wireless stations by dividing channel time into one or more superframes;

providing one or more schedules in each superframe for communicating information, wherein each schedule comprises one or more channel time blocks (CTBs) including one or more reserved CTBs for communication of packets of information over a channel; and

communicating packets of information over the channel during the reserved CTBs according to each schedule.

2. The method of claim 1 wherein a schedule further includes one or more unreserved CTBs for communication of control information.

3. The method of claim 1 wherein the information comprises video information and each schedule includes one or more reserved CTBs for communication of isochronous stream packets over the channel.

4. The method of claim 1 wherein:

controlling channel access further includes dividing channel time into one or more superframes including schedules of CTBs for a high-rate channel and a low-rate channel; and

transmitting packets further includes transmitting packets of video information from a sender to a receiver over a high-rate channel during reserved CTBs, and transmitting acknowledgment (ACK) packets from the receiver to the sender over a low-rate channel during the reserved CTBs.

5. The method of claim 4 further including transmitting periodic beacons, wherein each pair of successive beacons define a superframe therebetween, and each beacon includes schedule timing allocations for the succeeding superframe for dividing the channel time into CTBs.

6. The method of claim 4 wherein the superframe further comprises a contention-based control period (CBCP) for communicating control and management commands on the low-rate channel.

7. The method of claim 6 wherein the superframe further comprises a beam-tracking period for fine-tuning beamforming parameters to maintain link quality for beamforming transmissions over the high-rate channel.

8. The method of claim 6 wherein the superframe further comprises a beam-search period (BSP) for searching transmission beams.

9. The method of claim 6 wherein each beacon signals the start of a superframe.

10. The method of claim 6 wherein the beacon specifies the start time, and length of the CTBs for each schedule in the corresponding superframe.

11. The method of claim 10 wherein the beacon specifies allocation of CTBs to different stations including senders and receivers.

12. The method of claim 11 wherein the beacon further specifies allocation of CTBs to different video streams.

13. The method of claim 6 wherein channel access during the CFP is based on Time Division Duplex (TDD)

14. The method of claim 6 wherein each schedule comprises a series of evenly distributed reserved CTBs with equal length.

15. The method of claim 4 further comprising the step of dynamically extending a reserved CTB into a following unreserved CTB to allow further packet communication.

16. The method of claim 15 wherein the step of dynamically extending further includes:

a coordinator broadcasting a CTB extension announcement to announce that at least a portion of the unreserved CTB following the current reserved CTB is being used as an extension period for the current reserved CTB.

17. The method of claim 16 wherein the CTB extension announcement informs those stations that are not involved in communication during the current reserved CTB, to refrain from contending for the channel during the CTB extension period.

18. The method of claim 15 further comprising the step of communicating video information during the CTB extension period.

19. The method of claim 4 further comprising the step of dynamically truncating a reserved CTB.

20. The method of claim 18 further comprising the step of dynamically truncating the CTB extension period upon completion of communication of video information during the reserved CTB.

21. The method of claim 19 wherein the step of truncating further includes the step of dynamically releasing unused channel time within a reserved CTB.

22. The method of claim 19 wherein the step of truncating further includes broadcasting a truncation announcement to announce that stations can begin contention for the channel.

23. The method of claim 5 further comprising the step of dynamically rescheduling utilizing sub-beacons.

24. The method of claim 6 further comprising the step of performing power saving wherein power saving (PS) devices contend for the unreserved CTBs immediately after a beacon.

25. The method of claim 6 further comprising the steps of:

a sender station transmitting a bandwidth request command for transmission of both isochronous streams and asynchronous data over a channel; and

if sufficient bandwidth remains in the channel, then a coordinator station allocating a schedule in the CFP to the sender station.

26. The method of claim 25 further comprising the step of allocating multiple schedules to the sender.

27. The method of claim 25 further comprising the step of the sender station transmitting multiple streams to a receiver over the channel during the allocated schedule.

28. The method of claim 25 further comprising the steps of:

the sender station transmitting a stream to a receiver station over the channel during the allocated schedule; and

the receiver station transmitting an ACK to the sender during the schedule.

29. The method of claim 28 wherein during a CTB, one or more packets are transmitted from the sender station to the receiver station, and one or more corresponding ACKs are transmitted from the receiver station to the sender station.

30. A coordinator for managing communication of information over one or more wireless channels in a network, comprising:

a controller configured for receiving a bandwidth request from a source wireless station for transmission of information, and determining channel bandwidth availability; and

a scheduler configured for allocating available channel bandwidth by dividing channel time into one or more superframes, each superframe including one or more schedules comprising one or more channel time blocks (CTBs) that include one or more reserved CTBs for communication of packets of information over a channel.

31. The coordinator of claim 30 wherein a schedule further includes one or more unreserved CTBs for communication of control information.

32. The coordinator of claim 30 wherein the information comprises video information and each schedule includes one or more reserved CTBs for communication of isochronous stream packets over the channel.

33. The coordinator of claim 30 wherein the scheduler is configured for dividing a CFP into one or more superframes including schedules of CTBs for a high-rate channel and a low-rate channel, for transmitting packets of video information from the source wireless station to a destination wireless station over a high-rate channel during reserved CTBs, and transmitting ACK packets from the destination wireless station to the source wireless station over a low-rate channel during the reserved CTBs.

34. The coordinator of claim 33 wherein the scheduler is further configured for transmitting periodic beacons, wherein each pair of successive beacons define a superframe therebetween, and each beacon includes schedule timing allocations for the succeeding superframe for dividing the channel time into CTBs.

35. The coordinator of claim 33 wherein the superframe further comprises a contention-based control period (CBCP) for communicating control and management commands on the low-rate channel.

36. The coordinator of claim 35 wherein the superframe further comprises a beam-tracking period for fine-tuning beamforming parameters to maintain link quality for beamforming transmissions over the high-rate channel.

37. The coordinator of claim 35 wherein the superframe further comprises a Beam-Searching Period (BSP) for searching better transmission beams.

38. The coordinator of claim 35 wherein each beacon signals the start of a superframe.

39. The coordinator of claim 35 wherein the beacon specifies the start time, and length of the CTBs in the corresponding superframe.

40. The coordinator of claim 39 wherein the beacon specifies allocation of CTBs to different stations including senders and receivers.

41. The coordinator of claim 40 wherein the beacon further specifies allocation of CTBs to different video streams.

42. The coordinator of claim 35 wherein channel access during the CFP is based on Time Division Duplex (TDD)

43. The coordinator of claim 35 wherein each schedule comprises a series of evenly distributed reserved CTBs with equal length.

44. The coordinator of claim 33 wherein the scheduler is further configured for dynamically extending a reserved CTB into a following unreserved CTB to allow further communication.

45. The coordinator of claim 44 wherein the scheduler is further configured for dynamically extending a reserved CTB by broadcasting a CTB extension announcement to announce that at least a portion of the unreserved CTB following the current reserved CTB is being used as an extension period for the current reserved CTB.

46. The coordinator of claim 45 wherein the CTB extension announcement informs those stations that are not involved in communication during the current reserved CTB, to refrain from contending for the channel during the CTB extension period.

47. The coordinator of claim 44 wherein the source wireless station communicates video information during the CTB extension period.

48. The coordinator of claim 47 wherein the scheduler is further configured for dynamically truncating the CTB extension period upon completion of communication of video information during the reserved CTB.

49. The coordinator of claim 33 wherein the scheduler is further configured for dynamically truncating a reserved CTB.

50. The coordinator of claim 49 wherein the scheduler is further configured for dynamically releasing unused channel time within a reserved CTB.

51. The coordinator of claim 49 wherein the scheduler is further configured for broadcasting a truncation announcement to announce that stations can begin contention for the channel.

52. The coordinator of claim 35 wherein one or more stations perform power saving (PS) by contending for the unreserved CTBs immediately after a beacon.

53. A wireless station for communication of information over one or more wireless channels in a network, comprising:

a controller module configured for requesting reservation of available channel bandwidth from a coordinator for transmission of information; and

a communication module configured for communication of packets of information over a channel according to one or more schedules provided by the coordinator, wherein each schedule allocates available channel bandwidth by dividing channel time into one or more superframes, each superframe including one or more schedules comprising one or more channel time blocks (CTBs) that include one or more reserved CTBs for communication of packets of information over the channel.

54. The wireless station of claim 53 wherein a schedule divides channel time into one or more superframes including schedules of CTBs for a high-rate channel and a low-rate channel, and the communication module is further configured for transmitting packets of video information to a destination wireless station over a high-rate channel during reserved CTBs, and transmitting ACK packets from the destination wireless station to the source wireless station over a low-rate channel during the reserved CTBs.

55. The wireless station of claim 54 wherein the video information includes uncompressed video information.

56. The wireless station of claim 54 wherein the video information includes uncompressed high definition video information.

57. The wireless station of claim 54 wherein the coordinator transmits periodic beacons, wherein each pair of successive beacons define a superframe therebetween, and each beacon includes schedule timing allocations for the succeeding superframe for dividing the channel time into CTBs, such that the communication module is further configured for communication of packets of information over a channel using the schedule information in the beacon.

58. The wireless station of claim 57 wherein the communication module communicates information during a CTB extension period according to a schedule.

59. The wireless station of claim 57 wherein the communication module is further configured for transmitting a bandwidth request command for transmission of both isochronous streams and asynchronous data over a channel, and if sufficient bandwidth remains in the channel, then the coordinator station allocates a schedule in the CFP to the wireless station.

60. The wireless station of claim 57 wherein the communication module is further configured for performing power saving (PS) by contending for the unreserved CTBs immediately after a beacon.

61. The wireless station of claim 57 wherein the communication module is further configured for transmitting multiple streams to a receiver over the channel during an allocated schedule.

62. The wireless station of claim 57 wherein the communication module is further configured for transmitting a stream to a receiver station over the channel during the allocated schedule, such that the receiver station transmits an ACK to the wireless station during the schedule.

63. The wireless station of claim 57 wherein the communication module is further configured for transmitting one or more packets of information during a CTB to a receiver station, wherein one or more corresponding ACKs are transmitted from the receiver to the wireless station.