Adaptive call admission control for use in a wireless communication system

• US 20060126549A1
• Filed: 02/08/2006
• Published: 06/15/2006
• Est. Priority Date: 12/27/2000
• Status: Active Grant

• Current Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Bourlas, Yair, Stanwood, Kenneth L., Gilbert, Sheldon L., Spinar, Brian
• Granted Patent: US 7,289,467 B2
• Time in Patent Office: Days
• US Class Current: 370/310
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/535 based on resource usage policies
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 76/30 Connection release

Abstract

The invention relates to communication systems and to systems and methods for implementing adaptive call admission control (CAC) in such systems. Adaptive call admission control can determine what CPE to base station calls (connections) are allowed at any given time. CAC, coupled with precedence, can further determine what connections are suspended if less bandwidth is available than is currently committed. Multiple techniques are disclosed to select connections for suspension. These techniques include suspending enough connections through the affected CPE until there is enough bandwidth to meet the remaining commitment, randomly (or in a round robin fashion) choosing connection to suspend from the entire set of connection, and using precedence priority levels.

Claims

1. A process for controlling connections between a base station and a customer premise equipment (CPE) in a wireless communication system, wherein the base station and the CPE each are configured to adaptively adjust a PHY mode for an uplink which includes one or more connections, wherein a planned PHY mode is selected for the uplink and wherein a current PHY mode corresponds to the modulation technique used by the CPE to transmit data, the method comprising:

receiving an uplink that is modulated by a CPE using a current PHY mode;

determining a quality for a channel parameter for the uplink;

comparing the quality with a current PHY mode lower threshold;

comparing the quality with a current PHY mode upper threshold;

if either the current PHY mode upper or lower threshold has been crossed, determining a normalized hard bandwidth commitments for the uplink based on a second current PHY mode to be used by the CPE;

if the air link line rate exceeds the normalized hard bandwidth commitments between the CPE and the base station, applying the second current PHY mode to the uplink, else suspending a connection between the CPE and the base station.

2. The method of claim 1, wherein suspending the connection includes:

assigning a precedence level to each connection between the base station and the CPE, wherein the precedence level is utilized to select the suspended connection between the base station and the CPE.

3. The method of claim 1, wherein the suspended connection between the base station and the CPE is a new connection.

4. The method of claim 1, wherein the suspended connection is using a more robust PHY mode than a planned PHY mode.

5. The method of claim 1, wherein the suspended connection is randomly selected from connections between the CPE and the base station and from connections between a second CPE and the base station.

6. The method of claim 5, wherein the base station, the CPE, and the second CPE are all located in a sector.

7. The method of claim 6, wherein the suspended connection is selected in a round-robin fashion from connections between the CPE and the base station and from connections between the second CPE and the base station.

8. The method of claim 1, further comprising:

assigning a precedence priority value to each connection; and

suspending the connection based on the assigned precedence priority value.

9. The method of claim 8, wherein suspending the connection is performed in a round-robin fashion.

10. The method of claim 8, wherein suspending the connection is performed in a random fashion.

11. The method of claim 1, wherein the normalized hard bandwidth commitments include constant bit rate (CBR) connections.

12. The method of claim 1, wherein the normalized hard bandwidth commitments include a minimum cell rate (MCR) portion of a guaranteed frame rate (GFR) connection.

13. The method of claim 1, wherein the normalized hard bandwidth commitments include some function of sustainable cell rate (SCR) for variable bit rate (VBR) and variable bit rate real-time (VBR-rt) connections.

14. The method of claim 1, wherein the normalized hard bandwidth commitments include measured bandwidth requirements for connections.

15. The method of claim 1, further comprising:

selecting a less robust PHY mode for at least one connection between the CPE and the base station as a new current PHY mode;

determining a second normalized hard bandwidth commitments between the base station and the CPE based on the new current PHY mode;

if the air link line rate exceeds the second normalized hard bandwidth commitments, unsuspending the suspended connection between the base station and the CPE.

16. A process for controlling connections between a base station and a customer premise equipment (CPE) in a wireless communication system, wherein the base station and the CPE each are configured to adaptively adjust channel characteristics for a downlink which includes one or more connections, wherein a planned PHY mode is selected for the downlink and wherein a current PHY mode corresponds to the modulation technique used by the base station to transmit data, the method comprising:

receiving a downlink that is modulated by a base station using a current PHY mode;

determining a quality for a channel parameter for the downlink;

comparing the quality with a current PHY mode lower threshold;

comparing the quality with a current PHY mode upper threshold;

if either the current PHY mode upper or lower threshold has been crossed, determining a normalized hard bandwidth commitments for the downlink based on a second current PHY mode to be used by the base station;

if the air link line rate exceeds the normalized hard bandwidth commitments between the CPE and the base station, applying the second current PHY mode to the downlink, else suspending a connection between the CPE and the base station.

17. The method of claim 16, wherein suspending the connection includes:

assigning a precedence level to each connection between the base station and the CPE, wherein the precedence level is utilized to select the suspended connection between the base station and the CPE.

18. The method of claim 16, wherein the suspended connection between the base station and the CPE is a new connection.

19. The method of claim 16, wherein the suspended connection is using a more robust PHY mode than a planned PHY mode.

20. The method of claim 16, wherein the suspended connection is randomly selected from connections between the CPE and the base station and from connections between a second CPE and the base station.

21. The method of claim 20, wherein the base station, the CPE, and the second CPE are all located in a sector.

22. The method of claim 21, wherein the suspended connection is selected in a round-robin fashion from connections between the CPE and the base station and from connections between the second CPE and the base station.

23. The method of claim 16, further comprising:

assigning a precedence priority value to each connection; and

suspending the connection based on the assigned precedence priority value.

24. The method of claim 23, wherein suspending the connection is performed in a round-robin fashion.

25. The method of claim 23, wherein suspending the connection is performed in a random fashion.

26. The method of claim 16, wherein the normalized hard bandwidth commitments include constant bit rate (CBR) connections.

27. The method of claim 16, wherein the normalized hard bandwidth commitments include a minimum cell rate (MCR) portion of a guaranteed frame rate (GFR) connection.

28. The method of claim 16, wherein the normalized hard bandwidth commitments include some function of sustainable cell rate (SCR) for variable bit rate (VBR) and variable bit rate real-time (VBR-rt) connections.

29. The method of claim 16, wherein the normalized hard bandwidth commitments include measured bandwidth requirements for connections to provide a quality of service.

30. The method of claim 16, further comprising:

selecting a less robust PHY mode for at least one connection between the CPE and the base station as a new current PHY mode;

determining a second normalized hard bandwidth commitments between the base station and the CPE based on the new current PHY modes;

if the air link line rate exceeds the second normalized hard bandwidth commitments, unsuspending the suspended connection between the base station and the CPE.

31. A method for controlling bandwidth in a communication system that is configured for adaptive modulation where new and existing connections between customer premises equipments (CPEs) and a base station can be suspended and unsuspended depending on planned and current bandwidth utilization for the communication system, the method comprising:

determining a first planned PHY mode for a first connection between a base station and a first CPE;

receiving data which is modulated using a first current PHY mode via the first connection;

determining a signal quality for the received data;

comparing the signal quality with either an upper threshold value or a lower threshold value;

if the signal quality has increased across the upper threshold value, selecting a less robust PHY mode to replace the first current PHY mode for the first connection;

if the signal quality has decreased across the lower threshold value, selecting a more robust PHY mode to replace the first current PHY mode for the first connection;

if the more robust PHY mode is selected, comparing an air link line rate which is based on a reference PHY mode with a hard bandwidth commitment value for connections between the CPEs and base station which is base on a current PHY mode for each CPE'"'"'s connections; and

if the air link line rate does not exceed the hard bandwidth commitment value, suspending a second connection.

32. The method of claim 31, wherein the CPEs and the base station are located in a sector.

33. The method of claim 31, wherein the hard bandwidth commitment value includes constant bit rate (CBR) connections.

34. The method of claim 31, wherein the hard bandwidth commitment value includes a minimum cell rate (MCR) portion of a guaranteed frame rate (GFR) connection.

35. The method of claim 31, wherein the hard bandwidth commitment value includes some function of sustainable cell rate (SCR) for variable bit rate (VBR) and variable bit rate real-time (VBR-rt) connections.

36. The method of claim 31, wherein the hard bandwidth commitment value includes measured bandwidth requirements for connections to provide a quality of service.

37. The method of claim 31, wherein the suspended second connection is selected randomly from all connections between the base station and the CPEs.

38. The method of claim 31, wherein the suspended second connection is selected in a round robin fashion from all connections between the base station and the CPEs.

39. The method of claim 31, further comprising:

assigning a first precedence level to the first connection;

assigning a second precedence level to the second connection, wherein the second connection is suspended since the second precedence level has a lower priority than the first precedence level.

40. The method of claim 31, wherein radio frequency planning determines the first planned PHY mode.

41. The method of claim 31, wherein the signal quality is determined by measuring a bit error rate (BER).

42. The method of claim 31, wherein the signal quality is determined by measuring a signal to noise ratio (SNR).

43. The method of claim 39, wherein the suspended second connection is selected randomly from between the first and second connections, wherein the first and second connections have the same precedence level.

44. The method of claim 39, wherein the suspended connection is selected in a round-robin fashion from between the first and second connections, wherein the first and second connections have the same precedence level.

45. The method of claim 31, wherein the first planned PHY mode comprises a modulation technique coupled with forward error correction (FEC).

46. The method of claim 31, wherein the first current PHY mode comprises a modulation technique coupled with forward error correction (FEC).

47. A method for selecting connections to suspend between a base station and associated terminals in a wireless communication system, wherein the base station and the associated terminals each are configured to adaptively adjust channel characteristics for each of their connections, wherein a current PHY mode corresponds to the modulation technique used by the terminals and base station to transmit data, the method comprising:

changing a current PHY mode for a selected connection between a base station and associated terminals;

summing the hard bandwidth commitments between the base station and the associated terminals based on the current PHY mode for each connection;

determining an air link line rate for all connections between the base station and the associated terminals based on a reference PHY mode;

if the air link line rate exceeds the hard bandwidth commitments, allocating air link resources to the selected connection, else suspending at least one of the connections between the base station and the associated terminals.

48. The method of claim 47, wherein the hard bandwidth commitments is a total of all requested bandwidth between the associated terminals and the base station assuming each connection is modulated using its current PHY mode.

49. The system of claim 48, wherein the total of all requested bandwidth includes normalizing each connection'"'"'s bandwidth using each connection'"'"'s current PHY mode.

50. The method of claim 47, wherein the base station and the associated terminals are located in a sector.

51. The method of claim 47, wherein suspending the at least one of the connections includes suspending connections between the base station and the associated terminals in a round-robin fashion.

52. The method of claim 47, wherein suspending the at least one of the connections includes randomly suspending connections between the base station and the associated terminals.

53. The method of claim 47, further comprising:

assigning a precedence priority value to each of the connections; and

suspending the at least one of the connections based on the assigned precedence priority value.

54. The method of claim 53, wherein suspending the at least one of the existing connections is performed in a round-robin fashion.

55. The method of claim 53, wherein suspending the at least one of the existing connections is performed in a random fashion.