METHOD AND SYSTEM FOR SELECTING A TARGET CELL FOR HANDOVER OF USER EQUIPMENT IN A LONG TERM EVOLUTION SYSTEM

• US 20120170547A1
• Filed: 12/30/2010
• Published: 07/05/2012
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Oprescu-Surcobe, Valentin, Drozt, Peter M., Korus, Michael F., Newberg, Donald G., Pandey, Aparna
• Granted Patent: US 9,473,994 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/0094 Definition of hand-off measurement parameters
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services

Abstract

A method and system for selecting a target cell for handover of user equipment in a Long Term Evolution (LTE) communication system are described. In accordance with the method, a serving cell: determines virtual channels supported by each of a plurality of neighboring cells; determines a set of virtual channels of interest to a UE; selects a subset of the neighboring cells, which supports at least one virtual channel in the set of virtual channels of interest to the UE; modifies handover behavior, and uses results of the modified handover behavior to select one of the neighboring cells, from the subset, as a target cell for handover of the UE.

Claims

1. A method for selecting a target cell for handover of user equipment (UE) in a Long Term Evolution (LTE) system, the method comprising:

a serving cell performing;

determining virtual channels supported by each of a plurality of neighboring cells;

determining a set of virtual channels of interest to a UE;

selecting a subset of the neighboring cells, which supports at least one virtual channel in the set of virtual channels of interest to the UE;

modifying handover behavior, and using results of the modified handover behavior to select one of the neighboring cells, from the subset, as a target cell for handover of the UE.

2. The method of claim 1, wherein selecting the subset of the neighboring cells, comprises:

determining an active virtual channel of the UE; and

including in the subset all of the neighboring cells, from the plurality, that support the active virtual channel.

3. The method of claim 1, wherein selecting the subset of the neighboring cells, comprises:

determining that all of the virtual channels of interest to the UE are inactive; and

including in the subset all of the neighboring cells, from the plurality, that support any of the virtual channels of interest to the UE.

4. The method of claim 1, wherein selecting the subset of the neighboring cells comprises:

determining an active virtual channel of the UE;

determining that none of the neighboring cells, from the plurality, supports the active virtual channel; and

including in the subset at least one neighboring cell, from the plurality, that supports a different virtual channel of interest to the UE.

5. The method of claim 1, wherein modifying the handover behavior comprises, when selecting the target cell, considering only radio frequency measurement reports for the neighboring cells in the subset.

6. The method of claim 1, wherein modifying the handover behavior comprises setting reporting parameters to cause the serving cell to receive radio frequency measurement reports for neighboring cells in the subset more frequently than it receives radio frequency measurement reports for the remaining neighboring cells in the plurality.

7. The method of claim 1 further comprising, on handover, indicating to the target cell the virtual channels of interest to a UE.

8. The method of claim 1 further comprising, on handover, indicating to at least a portion of the plurality of neighboring cells the virtual channels of interest to a UE.

9. The method of claim 1, wherein the set of virtual channels of interest to the UE includes at least one virtual channel determined, by the serving cell, as a virtual channel on which the UE has transmitted.

10. The method of claim 1 further comprising receiving a message from the UE that indicates the set of virtual channels of interest to the UE.

11. The method of claim 10, wherein the message from the UE is also a keep alive message to the serving cell, which causes the serving cell to withhold disconnecting the UE from the LTE system.

12. The method of claim 10, wherein the message from the UE is sent over a default or a dedicated bearer for the UE.

13. The method of claim 10, wherein the message is decoded at an application server and then sent to the serving cell.

14. The method of claim 1, wherein the target cell is selected in accordance with a preferred order of the virtual channels in the set of virtual channels of interest to the UE.

15. The method of claim 1, wherein modifying the handover behavior comprises:

determining that the UE is not transmitting;

releasing the UE from an LTE connection; and

sending a notification to the target cell.

16. The method of claim 15 further comprising, the serving cell, sending a connection release message to the UE that redirects the UE to the target cell.

17. The method of claim 1, wherein the target cell was added by the serving cell as part of an extendable transmission area.

18. A serving cell in a Long Term Evolution (LTE) system, the serving cell comprising:

an interface to a user equipment (UE); and

a processing device coupled to the interface, wherein the processing device is programmed to;

determine virtual channels supported by each of a plurality of neighboring cells;

determine a set of virtual channels of interest to the UE;

select a subset of the neighboring cells, which supports at least one virtual channel in the set of virtual channels of interest to the UE;

modify handover behavior, and use results of the modified handover behavior to select one of the neighboring cells, from the subset, as a target cell for handover of the UE.

19. A non-transient computer-readable storage element having computer readable code stored thereon for programming a computer in a serving cell to perform a method for selecting a target cell for handover of user equipment (UE) in a Long Term Evolution (LTE) system, the method comprising:

determining virtual channels supported by each of a plurality of neighboring cells;

determining a set of virtual channels of interest to a UE;

selecting a subset of the neighboring cells, which supports at least one virtual channel in the set of virtual channels of interest to the UE;

modifying handover behavior, and using results of the modified handover behavior to select one of the neighboring cells, from the subset, as a target cell for handover of the UE.