Method and apparatus for scheduling in a wireless network

• US 20050270975A1
• Filed: 03/21/2005
• Published: 12/08/2005
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Abraham, Santosh, Meylan, Arnaud
• Granted Patent: US 8,401,018 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04B 7/0447 utilizing uniform distribution
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04W 28/0236 radio quality, e.g. interference, losses or delay
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

Techniques for scheduling flows and links for transmission are described. Each link is an oriented source-destination pair and carries one or more flows. Each flow may be associated with throughput, delay, feedback (e.g., acknowledgments (ACKs)) and/or other requirements. A serving interval is determined for each flow based on the requirements for the flow. A serving interval is determined for each link based on the serving intervals for all of the flows sent on the link. Each link is scheduled for transmission at least once in each serving interval, if system resources are available, to ensure that the requirements for all flows sent on the link are met. The links are also scheduled in a manner to facilitate closed loop rate control. The links are further scheduled such that ACKs for one or more layers in a protocol stack are sent at sufficiently fast rates.

Claims

1. A method of scheduling transmission, comprising:

obtaining at least one requirement for at least one flow of data; and

scheduling the at least one flow for transmission based on the at least one requirement for the at least one flow.

2. The method of claim 1, further comprising:

determining a serving interval for each of the at least one flow based on requirements, if any, for the flow.

3. The method of claim 2, wherein the scheduling the at least one flow for transmission comprises

scheduling each flow with at least one transmission opportunity (TXOP) in each serving interval for the flow if system resources are available.

4. The method of claim 1, further comprising:

determining a delay requirement for each flow; and

selecting a serving interval for each flow to meet the delay requirement for the flow.

5. The method of claim 1, further comprising:

determining a delay requirement for each flow;

determining number of transmissions allowed for any one data unit; and

selecting a serving interval for each flow based on the delay requirement for the flow and the number of transmissions allowed for any one data unit.

6. The method of claim 1, further comprising:

determining a throughput requirement for each flow; and

selecting a serving interval for each flow to meet the throughput requirement for the flow.

7. The method of claim 1, further comprising:

determining a feedback requirement for each flow; and

selecting a serving interval for each flow to meet the feedback requirement for the flow.

8. The method of claim 1, further comprising:

determining a rate for sending acknowledgments for each flow; and

selecting a serving interval for each flow to meet the acknowledgment rate for the flow.

9. An apparatus in a wireless network, comprising:

a controller operative to obtain at least one requirement for at least one flow of data; and

a scheduler operative to schedule the at least one flow for transmission based on the at least one requirement for the at least one flow.

10. The apparatus of claim 9, wherein the scheduler is further operative to determine a serving interval for each of the at least one flow based on requirements, if any, for the flow.

11. The apparatus of claim 10, wherein the scheduler is further operative to schedule each flow with at least one transmission opportunity (TXOP) in each serving interval for the flow if system resources are available.

12. The apparatus of claim 9, wherein the wireless network supports multiple-input multiple-output (MIMO) transmission.

13. An apparatus in a wireless network, comprising:

means for obtaining at least one requirement for at least one flow of data; and

means for scheduling the at least one flow for transmission based on the at least one requirement for the at least one flow.

14. The apparatus of claim 13, further comprising:

means for determining a serving interval for each of the at least one flow based on requirements, if any, for the flow.

15. The apparatus of claim 14, wherein the means for scheduling the at least one flow for transmission comprises

means for scheduling each flow with at least one transmission opportunity (TXOP) in each serving interval for the flow if system resources are available.

16. A method of scheduling transmission, comprising:

identifying at least one link, each link carrying at least one flow of data;

obtaining at least one requirement for the at least one flow for each link; and

scheduling the at least one link for transmission based on the at least one requirement for the at least one flow for each link.

17. The method of claim 16, further comprising:

determining a serving interval for each link based on the at least one requirement for the at least one flow for the link.

18. The method of claim 16, further comprising:

for each of the at least one link,

determining a serving interval for each flow for the link based on requirements, if any, for the flow, and

determining a serving interval for the link based on at least one serving interval determined for the at least one flow for the link.

19. The method of claim 17, wherein the determining the serving interval for each link comprises

determining a feedback requirement for the link, and

selecting the serving interval for the link to meet the feedback requirement for the link.

20. The method of claim 17, further comprising:

scheduling each link with at least one transmission opportunity (TXOP) in each serving interval for the link if system resources are available.

21. An apparatus in a wireless network, comprising:

a controller operative to identify at least one link, each link carrying at least one flow of data, and to obtain at least one requirement for the at least one flow for each link; and

a scheduler operative to schedule the at least one link for transmission based on the at least one requirement for the at least one flow for each link.

22. The apparatus of claim 21, wherein the scheduler is further operative to determine a serving interval for each link based on the at least one requirement for the at least one flow for the link.

23. The apparatus of claim 22, wherein the scheduler is further operative to schedule each link with at least one transmission opportunity (TXOP) in each serving interval for the link if system resources are available.

24. An apparatus in a wireless network, comprising:

means for identifying at least one link, each link carrying at least one flow of data;

means for obtaining at least one requirement for the at least one flow for each link; and

means for scheduling the at least one link for transmission based on the at least one requirement for the at least one flow for each link.

25. The apparatus of claim 24, further comprising:

means for determining a serving interval for each link based on the at least one requirement for the at least one flow for the link.

26. The apparatus of claim 25, wherein the means for scheduling the at least one link for transmission comprises

means for scheduling each link with at least one transmission opportunity (TXOP) in each serving interval for the link if system resources are available.

27. A method of scheduling data transmission, comprising:

identifying at least one link to schedule for data transmission based on requirements for the at least one link;

determining a transmission opportunity (TXOP) for each of the at least one link; and

scheduling each link with the TXOP determined for the link.

28. The method of claim 27, wherein the identifying the at least one link to schedule for data transmission comprises

identifying links that have not been scheduled for data transmission within serving intervals for the links.

29. The method of claim 27, wherein the identifying the at least one link to schedule for data transmission comprises

identifying links that have not been adequately served in a prior scheduling interval.

30. The method of claim 27, wherein the determining the TXOP for each of the at least one link comprises

determining amount of data to send for the link,

determining at least one rate to use for the link, and

computing duration of the TXOP for the link based on the amount of data to send and the at least one rate for the link.

31. The method of claim 27, wherein the determining the TXOP for each of the at least one link comprises

determining duration of the TXOP for the link based on a requested duration for the link.

32. The method of claim 27, further comprising:

sorting the at least one link based on priority, and wherein the at least one link is scheduled in a sorted order.

33. The method of claim 27, further comprising:

sorting the at least one link based on delay requirements for the at least one link, and wherein the at least one link is scheduled in a sorted order.

34. An apparatus in a wireless network, comprising:

a selector operative to identify at least one link to schedule for data transmission based on requirements for the at least one link;

a computation unit operative to determine a transmission opportunity (TXOP) for each of the at least one link; and

a scheduler operative to schedule each link with the TXOP determined for the link.

35. The apparatus of claim 34, wherein the selector is operative to identify links that have not been scheduled for data transmission within serving intervals for the links.

36. The apparatus of claim 35, wherein the computation unit is operative to determine duration of the TXOP for each link based on a requested duration for the link or a buffer size and at least one rate for the link.

37. An apparatus in a wireless network, comprising:

means for identifying at least one link to schedule for data transmission based on requirements for the at least one link;

means for determining a transmission opportunity (TXOP) for each of the at least one link; and

means for scheduling each link with the TXOP determined for the link.

38. The apparatus of claim 37, wherein the means for identifying at least one link to schedule for data transmission comprises

means for identifying links that have not been scheduled for data transmission within serving intervals for the links.

39. The apparatus of claim 38, further comprising:

means for determining duration of the TXOP for each link based on a requested duration for the link or a buffer size and at least one rate for the link.

40. A method of scheduling transmission, comprising:

identifying at least one link to be scheduled for data transmission in a first direction;

scheduling the at least one link for reverse transmission in a second direction opposite to the first direction; and

scheduling the at least one link for data transmission in the first direction.

41. The method of claim 40, wherein the at least one link is scheduled for reverse transmission in a first frame and for data transmission in a second frame after the first frame.

42. The method of claim 41, wherein the second frame immediately follows the first frame.

43. The method of claim 40, wherein the scheduling the at least one link for reverse transmission comprises

for each link with no data to send in the second direction, scheduling the link for reverse transmission of a null packet with at least one rate to use for the data transmission in the first direction.

44. An apparatus in a wireless network, comprising:

a selector operative to identify at least one link to be scheduled for data transmission in a first direction; and

a scheduler operative to schedule the at least one link for reverse transmission in a second direction opposite to the first direction and to schedule the at least one link for data transmission in the first direction.

45. The apparatus of claim 44, wherein the reverse transmission for each link comprises a pilot.

46. The apparatus of claim 44, wherein the reverse transmission for each link comprises at least one rate or at least one signal-to-noise ratio (SNR) estimate for the link.

47. The apparatus of claim 44, wherein the reverse transmission for each link comprises acknowledgments for prior data transmission in the first direction for the link.

48. An apparatus in a wireless network, comprising:

means for identifying at least one link to be scheduled for data transmission in a first direction;

means for scheduling the at least one link for reverse transmission in a second direction opposite to the first direction; and

means for scheduling the at least one link for data transmission in the first direction.

49. A method of scheduling data transmission, comprising:

identifying at least one data flow to be scheduled for data transmission;

determining a rate for sending acknowledgments for each of the at least one data flow; and

scheduling reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.

50. The method of claim 49, further comprising:

determining a serving interval for each data flow to achieve the acknowledgment rate for the flow.

51. The method of claim 49, further comprising:

identifying at least one acknowledgment (ACK) flow corresponding to the at least one data flow;

determining a rate of transmission for each ACK flow; and

scheduling each ACK flow at the rate determined for the ACK flow.

52. The method of claim 49, further comprising:

determining an amount of time to schedule for the reverse transmission for each data flow based on an estimated data rate for the data flow, physical layer overhead, acknowledgment (ACK) block size, or any combination thereof.

53. An apparatus in a wireless network, comprising:

a selector operative to identify at least one data flow to be scheduled for data transmission;

a computation unit operative to determine a rate for sending acknowledgments for each of the at least one data flow; and

a scheduler operative to schedule reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.

54. The apparatus of claim 53, wherein the acknowledgments are Medium Access Control (MAC) acknowledgments.

55. The apparatus of claim 54, wherein the computation unit is further operative to determine a serving interval for each data flow to achieve the acknowledgment rate for the flow.

56. The apparatus of claim 53, wherein the selector is further operative to identify at least one ACK flow corresponding to the at least one data flow, wherein the computation unit is further operative to determine a rate of transmission for each ACK flow, and wherein the scheduler is further operative to schedule each ACK flow at the rate determined for the ACK flow.

57. The apparatus of claim 56, wherein each ACK flow carries Transmission Control Protocol (TCP) ACKs for a corresponding data flow.

58. An apparatus in a wireless network, comprising:

means for identifying at least one data flow to be scheduled for data transmission;

means for determining a rate for sending acknowledgments for each of the at least one data flow; and

means for scheduling reverse transmission for each data flow to achieve the acknowledgment rate for the data flow.

59. The apparatus of claim 58, further comprising:

means for determining a serving interval for each data flow to achieve the acknowledgment rate for the flow.

60. The apparatus of claim 58, further comprising:

means for identifying at least one ACK flow corresponding to the at least one data flow;

means for determining a rate of transmission for each ACK flow; and

means for scheduling each ACK flow at the rate determined for the ACK flow.