Handing off a node from a first access point to a second access point

• US 7,466,981 B1
• Filed: 10/25/2005
• Issued: 12/16/2008
• Est. Priority Date: 10/25/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Laux, Carlos V., de Siqueira, Marcio Guidorizzi, Walker, Jennifer K., Abdelhamid, Hisham S., Toor, Kamaldip S.
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US11/259,570
• Time in Patent Office: 1,148 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/442, 455/443, 455/444, 455/450, 370/310, 370/331, 370/332, 370/333, 370/334, 370/338
• US Class Current: 455/438
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04W 36/08 Reselecting an access point

Abstract

Handing off a node from a first access point to a second access point includes facilitating communication between a node and a network using a first access point. A handoff rule of one or more handoff rules is accessed. One or more handoff factors associated with the first access point and a second access point are determined. A handoff factor is relevant in deciding whether to handoff from the first access point to the second access point. The handoff rule is applied to the one or more handoff factors. Handoff of the node to the second access point is initiated if the one or more handoff factors satisfy the applied handoff rule.

Claims

1. A method for handing off a node from a first access point to a second access point, comprising:

facilitating communication between a node and a network using a first access point;

accessing a handoff rule of one or more handoff rules;

determining one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

applying the handoff rule to the one or more handoff factors by;

determining a difference between a first Received Signal Strength Indicator (RSSI) value and a second RSSI value, the first RSSI value associated with the first access point, the second RSSI value associated with the second access point; and

initiating handoff of the node to the second access point if the one or more handoff factors satisfy the applied handoff rule by;

initiating handoff of the node to the second access point if the difference satisfies an RSSI differential threshold, the RSSI differential threshold comprising a first RSSI differential threshold if the first RSSI value is within a first range of values, the RSSI differential threshold comprising a second RSSI differential threshold if the first RSSI value is within a second range of values, the first range of values less than the second range of values, the first RSSI differential threshold less than the second RSSI differential threshold.

2. The method of claim 1, further comprising determining the first RSSI value by:

applying an averaging technique to a plurality of RSSI values;

determining an average of the applied averaging technique; and

establishing the first RSSI value from the average of the applied averaging technique.

3. The method of claim 1, wherein:

applying the handoff rule comprises;

monitoring a number of transaction failures, a transaction failure comprising a failed attempt of the node to communicate with the first access point; and

initiating handoff of the node to the second access point comprises;

initiating handoff of the node to the second access point if the number of transaction failures satisfies a consecutive transaction failures threshold.

4. The method of claim 1, wherein:

applying the handoff rule comprises;

determining whether the first access point has one or more available slots to facilitate communication; and

initiating handoff of the node to the second access point comprises;

initiating handoff to a second access point if the first access point does not have one or more available slots.

5. The method of claim 1, wherein:

applying the handoff rule comprises;

determining a number of available slots the first access point has to facilitate communication;

determining a number of available slots a second access point has to facilitate communication;

comparing the number of available slots of the first access point to the number of available slots of the second access point; and

initiating handoff of the node to the second access point comprises;

initiating handoff to the second access point if the number of available slots of the second access point exceeds the number of available slots of the first access point.

6. A method for handing off a node from a first access point to a second access point, comprising:

facilitating communication between a node and a network using a first access point;

accessing a handoff rule of one or more handoff rules;

determining one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

applying the handoff rule to the one or more handoff factors by;

determining a first channel utilization value associated with the first access point;

determining a second channel utilization value associated with the second access point; and

determining a channel utilization difference between the first channel utilization value and the second channel utilization value; and

initiating handoff of the node to the second access point if the channel utilization difference satisfies a channel utilization differential threshold, the channel utilization differential threshold comprising a first channel utilization differential threshold if the first channel utilization value is within a first range of values, the channel utilization differential threshold comprising a second channel utilization differential threshold if the first channel utilization value is within a second range of values, the first range of values less than the second range of values, the first channel utilization differential threshold greater than the second channel utilization differential threshold.

7. A system for handing off a node from a first access point to a second access point, comprising:

a first access point operable to facilitate communication between a node and a network; and

the node operable to;

access a handoff rule of one or more handoff rules;

determine one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

apply the handoff rule to the one or more handoff factors by;

determining a difference between a first Received Signal Strength Indicator (RSSI) value and a second RSSI value, the first RSSI value associated with the first access point, the second RSSI value associated with the second access point; and

initiate handoff of the node to the second access point if the one or more handoff factors satisfy the applied handoff rule by;

initiating handoff of the node to the second access point if the difference satisfies an RSSI differential threshold, the RSSI differential threshold comprising a first RSSI differential threshold if the first RSSI value is within a first range of values, the RSSI differential threshold comprising a second RSSI differential threshold if the first RSSI value is within a second range of values, the first range of values less than the second range of values, the first RSSI differential threshold less than the second RSSI differential threshold.

8. The system of claim 7, the node further operable to:

apply an averaging technique to a plurality of RSSI values;

determine an average of the applied averaging technique; and

establish the first RSSI value from the average of the applied averaging technique.

9. The system of claim 7, the node further operable to:

monitor a number of transaction failures, a transaction failure comprising a failed attempt of the node to communicate with the first access point; and

initiate handoff of the node to the second access point if the number of transaction failures satisfies a consecutive transaction failures threshold.

10. The system of claim 7, the node further operable to:

determine whether the first access point has one or more available slots to facilitate communication; and

initiate handoff to a second access point if the first access point does not have one or more available slots.

11. The system of claim 7, the node further operable to:

determine a number of available slots the first access point has to facilitate communication;

determine a number of available slots a second access point has to facilitate communication;

compare the number of available slots of the first access point to the number of available slots of the second access point; and

initiate handoff to the second access point if the number of available slots of the second access point exceeds the number of available slots of the first access point.

12. A system for handing off a node from a first access point to a second access point, comprising:

a first access point operable to facilitate communication between a node and a network; and

the node operable to;

access a handoff rule of one or more handoff rules;

determine one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

apply the handoff rule to the one or more handoff factors by;

determining a first channel utilization value associated with the first access point;

determining a second channel utilization value associated with the second access point; and

determining a channel utilization difference between the first channel utilization value and the second channel utilization value; and

initiate handoff of the node to the second access point if the channel utilization difference satisfies a channel utilization differential threshold, the channel utilization differential threshold comprising a first channel utilization differential threshold if the first channel utilization value is within a first range of values, the channel utilization differential threshold comprising a second channel utilization differential threshold if the first channel utilization value is within a second range of values, the first range of values less than the second range of values, the first channel utilization differential threshold greater than the second channel utilization differential threshold.

13. A node of a communication network, comprising:

an interface operable to communicate with a first access point; and

a handoff initiator operable to;

access a handoff rule of one or more handoff rules;

determine one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

apply the handoff rule to the one or more handoff factors by;

determining a difference between a first Received Signal Strength Indicator (RSSI) value and a second RSSI value, the first RSSI value associated with the first access point, the second RSSI value associated with the second access point; and

initiate handoff of the node to the second access point if the one or more handoff factors satisfy the applied handoff rule by;

initiating handoff of the node to the second access point if the difference satisfies an RSSI differential threshold, the RSSI differential threshold comprising a first RSSI differential threshold if the first RSSI value is within a first range of values, the RSSI differential threshold comprising a second RSSI differential threshold if the first RSSI value is within a second range of values, the first range of values less than the second range of values, the first RSSI differential threshold less than the second RSSI differential threshold.

14. The node of claim 13, the handoff initiator further operable to:

apply an averaging technique to a plurality of RSSI values;

determine an average of the applied averaging technique; and

establish the first RSSI value from the average of the applied averaging technique.

15. The node of claim 13, the handoff initiator further operable to:

monitor a number of transaction failures, a transaction failure comprising a failed attempt of the node to communicate with the first access point; and

initiate handoff of the node to the second access point if the number of transaction failures satisfies a consecutive transaction failures threshold.

16. The node of claim 13, the handoff initiator further operable to:

determine whether the first access point has one or more available slots to facilitate communication; and

initiate handoff to a second access point if the first access point does not have one or more available slots.

17. The node of claim 13, the handoff initiator further operable to:

determine a number of available slots the first access point has to facilitate communication;

determine a number of available slots a second access point has to facilitate communication;

compare the number of available slots of the first access point to the number of available slots of the second access point; and

initiate handoff to the second access point if the number of available slots of the second access point exceeds the number of available slots of the first access point.

18. A node of a communication network, comprising:

an interface operable to communicate with a first access point; and

a handoff initiator operable to;

access a handoff rule of one or more handoff rules;

determine one or more handoff factors associated with the first access point and a second access point, a handoff factor relevant in deciding whether to handoff from the first access point to the second access point;

apply the handoff rule to the one or more handoff factors by;

determining a first channel utilization value associated with the first access point;

determining a second channel utilization value associated with the second access point; and

determining a channel utilization difference between the first channel utilization value and the second channel utilization value; and

initiate handoff of the node to the second access point if the channel utilization difference satisfies a channel utilization differential threshold, the channel utilization differential threshold comprising a first channel utilization differential threshold if the first channel utilization value is within a first range of values, the channel utilization differential threshold comprising a second channel utilization differential threshold if the first channel utilization value is within a second range of values, the first range of values less than the second range of values, the first channel utilization differential threshold greater than the second channel utilization differential threshold.

19. A system for handing off node from a first access point to a second access point, comprising:

means for facilitating communicating between a node and a network using a first access point;

means for accessing a handoff rule of one or more handoff rules;

means for determining one or more handoff factors associated with the first access point and a second access point, a handoff factor revelant in deciding whether to handoff from the first access point to the second access point;

means for applying the handoff rule to the one or more handoff factors by;

determining a difference between a first Received Signal Strength Indicator (RSSI) value and a second RSSI value, the first RSSI value associated with the first access point, the second RSSI value associated with the second access point; and

means for initiating handoff of the node to the second access point if the one or more handoff factors satisfy the applied handoff rule by;

initiating handoff of the node to the second access point if the difference satisfies an RSSI differential threshold, the RSSI differential threshold comprising a first RSSI differential threshold if the first RSSI value is within a first range of values, the RSSI differential threshold comprising a second RSSI differential threshold if the first RSSI value is within a second range of values, the first range of values less than the second range of values, the first RSSI differential threshold less than the second RSSI differential threshold.