Method Of Providing Hand-Off Hysteresis For Subnet Borders

• US 20120257597A1
• Filed: 04/07/2011
• Published: 10/11/2012
• Est. Priority Date: 04/07/2011
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Zhang, Bulin, Lamoureux, Philip
• Granted Patent: US 8,817,661 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• 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 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.

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. A method of paging an access terminal (AT) in a communications network including a plurality of areas, the method comprising:

receiving at a controller a location update message from the AT indicating an area, from among the plurality of areas, in which the AT is located; and

paging the AT by

determining, at the controller, a radius value based on the location update message, and

sending at least one paging message to one or more areas, from among the plurality of areas, within a region defined by the area indicated in the location update message and the determined radius.

10. The method of claim 9 wherein determining the radius value includes

accessing, in a database in the controller, a stored distance value associated with the area indicated in the location update message, and

determining, at the controller, the stored distance value associated with the area indicated in the location update message to be the determined radius value.

11. The method of claim 10 wherein sending the at least one paging message includes accessing, in the database of the controller, stored locations of the plurality of areas,

calculating, based on the stored locations, which areas have locations that are within the defined region, the defined region being a region having a center at a location of the area indicated in the location update message and borders extending a distance equal to the determined radius value outwards from the location of the indicated area, and

sending the at least one paging message to one or more areas calculated as having locations within the defined region.

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

receiving a location update message at the first controller, the first controller being associated with the first subnet, the location update message including access terminal (AT) identification information and controller identification information;

determining if the controller identification information indicates a second controller different from the first controller; and

if the controller identification information identifies the second controller,

forwarding the location update message to the second controller, and

receiving, from the second controller, session information associated with the AT, in response to the forwarding of the location update message.

13. The method of claim 12 further comprising:

assigning a subnet identifier of the first subnet to the AT, if the controller identification information identifies the second controller.

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

receiving a location update request at the first controller, the first controller being associated with the first subnet, the location update message including access terminal (AT) identification information;

determining whether the location update message was received from a second controller different from the first controller; and

if the location information message was received from the second controller,

determining, at the first controller, session information for the AT indicated by the AT identification information, and

forwarding, to the second controller, the session information associated for the AT, in response to receipt of the location update message.

15. A controller device for facilitating communications in a communications network including a plurality of areas divided into at least a first and second subnet, the controller device comprising:

a receiver unit configured to receive data from other network elements of the communications network;

a transmitting unit configured to transmit data to other network elements of the communications network;

a memory unit configured to store at least address information associated with other controllers in the communications network; and

a processing unit coupled to the transmitting unit, the receiving unit, and the memory unit, and configured to control operations including

receiving a location update message at the first controller, the first controller being associated with the first subnet, the location update message including access terminal (AT) identification information and controller identification information;

determining if the controller identification information indicates a second controller different from the first controller; and

if the controller identification information identifies the second controller,

forwarding the location update message to the second controller, and

receiving, from the second controller, session information associated with the AT, in response to the forwarding of the location update message.

16. The controller device of claim 15, wherein the processing unit is further configured to control assigning a subnet identifier of the first subnet to the AT, if the controller identification information identifies the second controller.

17. A controller device for facilitating communications in a communications network including a plurality of areas divided into at least a first and second subnet, the controller device comprising:

a receiver unit configured to receive data from other network elements of the communications network;

a transmitting unit configured to transmit data to other network elements of the communications network;

a memory unit configured to store at least session information for access terminals (ATs) associated with the controller, and address information associated with other controllers in the communications network; and

a processing unit coupled to the transmitting unit, the receiving unit, and the memory unit, and configured to control operations including

receiving a location update request at the first controller, the first controller being associated with the first subnet, the location update message including AT identification information;

determining whether the location update message was received from a second controller different from the first controller; and

if the location information message was received from the second controller,

determining, at the first controller, session information for the AT indicated by the AT identification information, and

forwarding, to the second controller, the session information associated for the AT, in response to receipt of the location update message.

18. A method of operating an access terminal (AT) in a communications network including a plurality of areas divided into at least a first and second subnet, the method comprising:

moving from a first cell in the first subnet to a cell in the second subnet;

receiving, at the AT, location information associated with the second cell;

performing a comparison operation based on the location information of the second cell and location information of the first cell stored in the AT; and

based on the comparison,

sending, from the AT, a location update message to a network element in the second cell, and

receiving, at the AT, a subnet identifier associated with the second subnet.

19. The method of claim 18, wherein the comparison operation includes

determining a traveled distance, the traveled distance being a distance between the location of the first cell and the location of the second cell, and

determining whether the traveled distance exceeds the maximum distance parameter of the first cell, and

wherein the location update message is sent and the subnet identifier is received if the traveled distance exceeds the maximum distance parameter of the first cell.

20. The method of claim 18, wherein receipt of the subnet identifier at the AT is not based on a subnet identifier request sent from the AT.