Adaptive call admission control for use in a wireless communication system

• US 7,529,204 B2
• Filed: 03/29/2007
• Issued: 05/05/2009
• Est. Priority Date: 12/27/2000
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Harper; Kevin C
• Application Number:
  US11/693,546
• Publication Number:
  US 20070165562A1
• Time in Patent Office: 768 Days
• Field of Search: 370/310, 370/328, 370/465, 370/468
• US Class Current: 370/328
• 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 method for allocating bandwidth among connections in a wireless communication system between a base station and associated customer premise equipments (CPEs), including a requesting CPE, where the modulation scheme of the uplinks and downlinks can be varied over time, the method comprising:

receiving a request for additional bandwidth for an existing connection from a requesting CPE;

summing hard bandwidth commitments of a base station and CPEs associated with the base station based on a planned modulation scheme for each connection;

determining an air link line rate between the base station and associated CPEs; and

allocating additional bandwidth to the requesting CPE if the air link line rate exceeds the hard bandwidth commitments and determining a second hard bandwidth commitment for the existing connections between the base station and the associated CPEs based on a current modulation scheme for each connection where the current modulation scheme for at least one of the connections is different than the planned modulation scheme for that connection, else denying the bandwidth request;

if the air link line rate exceeds the second hard bandwidth commitments, allocating air link resources to the requesting CPE, else denying the request for additional bandwidth.

2. The method of claim 1, further comprising de-allocating bandwidth from existing connections to decrease the hard bandwidth commitments.

3. The method of claim 2, wherein de-allocating bandwidth comprises changing the modulation scheme of one or more of the CPEs.

4. The method of claim 2, wherein de-allocating bandwidth comprises changing the modulation scheme of the base station.

5. The method of claim 2, wherein de-allocating bandwidth comprises changing the modulation scheme to a less robust modulation scheme.

6. The method of claim 2, wherein de-allocating bandwidth comprises changing a forward error correction scheme.

7. The method of claim 2, wherein de-allocating bandwidth from existing connections is based on a priority of an existing connection.

8. The method of claim 1, wherein the additional air link resources include available bandwidth in an uplink subframe and available bandwidth in a downlink subframe.

9. The method of claim 1, wherein the hard bandwidth commitments are summed with reference to the modulation scheme used to determine the air link rate.

10. The method of claim 1, wherein summing the hard bandwidth commitments between the base station and associated CPEs is based on a planned modulation scheme and a forward error correction scheme for each connection.

11. The method of claim 1, further comprising:

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

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

12. The method of claim 1, wherein summing the hard bandwidth commitments for the existing connections between the base station and the associated CPEs is further based on a forward error correction scheme for each connection.

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

14. The method of claim 1, wherein the 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.

15. The method of claim 1, wherein the hard bandwidth commitments include measured bandwidth requirements for connections to provide a quality of service.

16. A method for allocating bandwidth among connections between a base station and associated customer premise equipment (CPE) in a wireless communication system that supports adaptive modulation schemes, the method comprising:

receiving a request for additional bandwidth for an existing connection from a requesting CPE;

summing hard bandwidth commitments of the base station and CPEs associated with the base station based on a planned modulation scheme for each connection;

determining an air link line rate which represents the amount of bandwidth available between the base station and associated CPEs; and

allocating additional bandwidth to the requesting CPE if the air link line rate exceeds the hard bandwidth commitments, else determining if a second CPE has a lower priority than the requesting CPE and if it does, de-allocating bandwidth from the second CPE and allocating additional bandwidth to the requesting CPE.

17. A method for controlling connections between a base station and associated customer premise equipment (CPE) in a wireless communication system where the modulation scheme of the uplink and downlink can change over time, the method comprising:

receiving a request for additional bandwidth from a requesting CPE;

determining selected modulation schemes for the plurality of CPEs based on their planned modulation techniques and quality of service requirements;

determining a reference line rate for the communication system when using a reference modulation scheme;

determining multiplicative rates for normalizing CPEs selected modulation schemes to the reference modulation scheme;

comparing the reference line rate to bandwidth requirements using the normalized selected modulation schemes;

allowing or denying the request for additional bandwidth based on the comparison.

18. A method for allocating bandwidth among connections in a wireless communication system between a base station and associated customer premise equipments (CPEs), including a requesting CPE, where the modulation scheme of the uplinks and downlinks can be varied over time, the method comprising:

receiving a request for additional bandwidth for an existing connection from a requesting CPE;

summing bandwidth commitments of the base station based on current modulation schemes for each connection, where the current modulation scheme for at least one of the connections is different from a planned modulation scheme for that connection;

determining an amount of available bandwidth of the base station; and

allocating additional bandwidth to the requesting CPE if the available bandwidth exceeds the bandwidth commitments, else determining if a second CPE has a lower preference than the requesting CPE and if it does, de-allocating bandwidth from the second CPE and allocating additional bandwidth to the requesting CPE.

19. A base station in a wireless communication system where the modulation scheme of the uplinks and downlinks can be varied over time, the base station comprising:

a receive module that receives a request for additional bandwidth from a requesting customer premise equipment (CPE); and

a control module that

sums hard bandwidth commitments of the base station and CPEs associated with the base station based on a planned modulation scheme for each connection,

determines an air link line rate between the base station and associated CPEs,

allocates additional bandwidth to the requesting CPE

if the air link line rate exceeds the hard bandwidth commitments and determines a second hard bandwidth commitment for the existing connections between the base station and the associated CPEs based on a current modulation scheme for each connection where the current modulation scheme for at least one of the connections is different than the planned modulation scheme for that connection,

else denying the new connection, and

if the air link line rate exceeds the second hard bandwidth commitments, allocates air link resources to the requesting CPE, else denying the request for additional bandwidth.

20. A communication system that allocates bandwidth among existing connections between a base station and a plurality of customer premise equipments (CPEs) the system comprising:

a first CPE having a first modem that modulates data using a first current modulation scheme and a first initial modulation scheme different from the first current modulation scheme;

a second CPE having a second modem that modulates data using a second current modulation scheme and a second initial modulation scheme;

a base station having a third modem that transmits and receives data to and from the first and second CPEs; and

a control module that determines whether to re-allocate bandwidth among the first and second CPEs in response to bandwidth requests from the CPEs, by summing bandwidth commitments of the base station based on first current modulation scheme and the second current modulation scheme, determining an amount of available bandwidth of the base station, and if the available bandwidth exceeds the bandwidth commitments, allocates additional bandwidth to the CPE requesting additional bandwidth, else determining if a second CPE has a lower preference than the requesting CPE and if it does, de-allocating bandwidth from the second CPE and allocating additional bandwidth to the requesting CPE.

21. The system of claim 20, wherein the control module is located at the first CPE.

22. The system of claim 20, wherein the control module is located at the base station.

23. The system of claim 20, wherein the third modem comprises:

a transmitter module configured to convert digital data to a modulated analog signal; and

a receiver module configured to demodulate an analog modulated signal to digital form.

24. The system of claim 23, wherein the third modem further comprises:

a Receive Signal Quality (RSQ) module coupled with the receiver module and configured to monitor signal quality of existing connections between the first CPE and the base station, and the second CPE and the base station; and

a control module interfaced with the RSQ module and the transmitter module, and configured to select the first current modulation scheme for the first CPE based on the signal quality monitored by the RSQ module, and configured to select the second current modulation scheme for the second CPE based on the signal quality monitored by the RSQ module.

25. The system of claim 24, wherein the third modem further comprises a precedence module, interfaced with the control module, that identifies priorities associated with the CPEs and bandwidth is allocated among the CPEs based in part on their associated priorities.

26. A method for allocating bandwidth among connections between a base station and a plurality of customer premise equipment (CPEs) in a wireless communication system wherein the base station and the plurality of CPEs each are configured to adaptively adjust channel characteristics for an uplink which includes one or more connections, wherein a planned modulation scheme is selected for the uplink and wherein a current modulation scheme corresponds to the modulation technique used by a first CPE to transmit data to the base station, the method comprising:

receiving an uplink that is modulated by the first CPE using a first modulation scheme;

determining a quality for a channel parameter for the uplink;

comparing the quality with a first modulation scheme threshold value;

determining if the quality is less than the first modulation scheme threshold value, and if it is then determining if additional bandwidth is available to allocate to the CPE by determining a normalized hard bandwidth requirement and comparing it to an air link line rate, wherein if additional bandwidth is available then allocating it to the CPE, else replacing the first modulation scheme threshold value with a second modulation scheme threshold value.

27. The method of claim 26, wherein the second modulation scheme threshold value is less than the first modulation scheme threshold value.

28. A computer program product, comprising:

computer-readable medium comprising computer instructions that when executed cause a computer to;

receiving a request for additional bandwidth for an existing connection from a requesting CPE,

summing hard bandwidth commitments of the base station and CPEs associated with the base station based on a planned modulation scheme for each connection;

determining an air link line rate which represents the amount of bandwidth available between the base station and associated CPEs; and

allocating additional bandwidth to the requesting CPE if the air link line rate exceeds the hard bandwidth commitments, else determining if a second CPE has a lower priority than the requesting CPE and if it does, de-allocating bandwidth from the second CPE and allocating additional bandwidth to the requesting CPE.

29. A computer program product, comprising:

computer-readable medium comprising computer instructions that when executed cause a computer to;

receiving a request for additional bandwidth for an existing connection from a requesting CPE;

summing hard bandwidth commitments of a base station and CPEs associated with the base station based on a planned modulation scheme for each connection;

determining an air link line rate between the base station and associated CPEs; and

allocating additional bandwidth to the requesting CPE if the air link line rate exceeds the hard bandwidth commitments and determining a second hard bandwidth commitment for the existing connections between the base station and the associated CPEs based on a current modulation scheme for each connection where the current modulation scheme for at least one of the connections is different than the planned modulation scheme for that connection, else denying the bandwidth request;

if the air link line rate exceeds the second hard bandwidth commitments, allocating air link resources to the requesting CPE, else denying the request for additional bandwidth.