Method of providing hand-off hysteresis for subnet borders

• US 8,817,661 B2
• Filed: 04/07/2011
• Issued: 08/26/2014
• Est. Priority Date: 04/07/2011
• Status: Expired due to Fees

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Zhang, Bulin, Lamoureux, Philip
• Primary Examiner(s): Sefcheck, Gregory
• Assistant Examiner(s): MITCHELL, DANIEL D
• Application Number:
  US13/081,902
• Publication Number:
  US 20120257597A1
• Time in Patent Office: 1,237 Days
• Field of Search: None
• US Class Current: 370/254
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 36/0064 of control information between different access points

Abstract

In one embodiment, at least one grouping message is broadcast from a network element. The grouping message causes an access terminal (AT) in the communications network to regard the at least first and second subnets as both being members of a same subnet group. Location information and a maximum distance parameter associated with at least one area and configured to create a buffer zone along a border between the first and second subnets are broadcasted from the network element to the AT. The AT is prevented from sending a subnet identifier request message when the AT has, as an origin area, an area of the first subnet in the buffer zone and the AT travels to an area of the second subnet in the buffer zone. Session transfers are performed outside the buffer zone triggered by distance based location update messages, thus preventing session transfer ping-ponging.

Claims

1. A method of operating a communications network including a plurality of areas divided into at least a first and second subnet, the method comprising:

broadcasting, from a network element, at least one grouping message causing an access terminal (AT) in the communications network to regard the at least first and second subnets as both being members of a same subnet group;

broadcasting from the network element to the AT location information and a maximum distance parameter associated with at least one area from among the plurality of areas, the grouping message and the maximum distance parameter being configured to create a buffer zone along a border between the first and second subnets, the AT being prevented from sending a subnet identifier request message and prevented from sending a location update message when the AT travels such that

an origin area of the AT is an area of the first subnet in the buffer zone,

a visited area of the AT is an area within both the second subnet and the buffer zone, and

a traveled distance of the AT is less than a distance indicated by the maximum distance value, the traveled distance being a distance between the origin area and the visited area, the origin area of the AT being an area the AT was attached to when a last location update was sent, from among the plurality of areas the visited area being an area the AT is currently attached to, from among the plurality of areas.

2. The method of claim 1 wherein the network element is an access network (AN) including at least one controller and at least one base station (BS).

3. The method of claim 2 wherein the controller is a radio network controller (RNC).

4. The method of claim 2 wherein the grouping message includes a plurality of bits divided into a plurality of fields including a controller ID field and a controller group ID field, and

wherein broadcasting the grouping message includes broadcasting, from the at least one BS, the grouping message and a mask length indicator indicating a length corresponding to a group of contiguous, most significant bits in the grouping message, not including all of the bits of the controller ID field.

5. The method of claim 2 wherein the at least one area is an area for which the BS provides wireless coverage, and broadcasting the location information and maximum distance parameter includes broadcasting from the at least one BS to the at least one area, the location information and the maximum distance parameter.

6. The method of claim 5 wherein the location information includes longitude and latitude values of a geographical coordinate within the at least one area.

7. The method of claim 1 wherein the communications network follows a code division multiple access (CDMA) evolution data optimized (EVDO) protocol.

8. The method of claim 1 wherein the plurality of areas are each at least one of cells and sectors of cells.

9. The method of claim 1, wherein the maximum distance value is a threshold value for the AT such that

while the traveled distance of the AT remains below the threshold value, the AT does not send a location update message to the communications network, and

when the traveled distance of the AT exceeds the threshold value, the AT sends a location update message to the communications network.