Methods for mobility management of user equipment in a long term evolution system

• US 8,195,166 B1
• Filed: 12/30/2010
• Issued: 06/05/2012
• 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
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): Ajayi, Joel
• Application Number:
  US12/981,923
• Time in Patent Office: 523 Days
• Field of Search: 455/432.1, 455436-444
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• 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 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states

Abstract

A UE connected to a serving cell: determines a set of virtual channels of interest to the UE; determines that the UE is in one of a plurality of ACTIVE states; detects occurrence of an event effecting service availability for the UE; and determines behavior of the UE based on the ACTIVE state of the UE and the occurrence of the event. A UE in an IDLE state: determines a set of virtual channels of interest to the UE; determines a list of cells, wherein each cell in the list supports at least one of the virtual channels; determines a candidate subset of the list of cells, wherein inclusion of a cell in the candidate subset is based on whether or not the UE is receiving on a downlink path of one of the virtual channels; and selects one of the cells in the candidate subset as a target cell.

Claims

1. A method for mobility management of user equipment (UE) in a long term evolution (LTE) system, the method comprising:

a UE connected to a serving cell, the UE performing;

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

determining that the UE is in one of a plurality of ACTIVE states based on whether or not the UE is transmitting or receiving on one of the virtual channels of interest to the UE;

detecting occurrence of an event effecting service availability for the UE;

determining behavior of the UE based on the ACTIVE state of the UE and the occurrence of the event;

wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises an uplink path and a downlink path, wherein the first virtual channel supports media transmissions for a first application on the UE, wherein the ACTIVE state comprises the UE transmitting on the uplink path, wherein when the event comprises the UE receiving, from the serving cell, a command to execute a handover to a target cell, the UE performing;

determining whether the target cell supports the first virtual channel;

when the target cell supports the first virtual channel, executing the handover to the target cell;

when the target cell does not support the first virtual channel, but a second application that does not use the first virtual channel is running on the UE and is exchanging information with the serving cell, executing the handover to the target cell, and releasing a bearer that comprises the uplink path;

otherwise, ignoring the command to execute the handover to the target cell.

2. The method of claim 1, wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises an uplink path and a downlink path, wherein the ACTIVE state comprises the UE transmitting on the uplink path, wherein the event comprises an order, from the serving cell, to transition the UE to an IDLE state, the method further comprising:

the UE performing;

transitioning to the IDLE state;

listening to the downlink path of the first virtual channel while in IDLE state.

3. The method of claim 1, wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises an uplink path and a downlink path, wherein the first virtual channel supports media transmissions for a first application on the UE, wherein the ACTIVE state comprises the UE transmitting on the uplink path, wherein the event comprises the UE determining that a time has arrived to send to the serving cell a radio frequency (RF) measurement report for another cell, the method further comprising:

the UE performing;

determining whether the other cell supports the first virtual channel;

when the other cell supports the first virtual channel, sending the RF measurement report for the other cell;

when the other cell does not support the first virtual channel, and a second application that does not use the first virtual channel is running on the UE and is exchanging information with the serving cell, sending the RF measurement report for the other cell;

otherwise withholding sending the RF measurement report for the other cell.

4. The method of claim 1, wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises at least a downlink path, wherein the ACTIVE state comprises the UE receiving on the downlink path, wherein the event comprises an order, from the serving cell, to transition the UE to an IDLE state, the method further comprising:

the UE performing;

transitioning to the IDLE state;

continuing to receive on the downlink path of the first virtual channel, while in the IDLE state.

5. A method for mobility management of user equipment (UE) in a long term evolution (LTE) system, the method comprising:

a UE connected to a serving cell, the UE performing;

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

determining that the UE is in one of a plurality of ACTIVE states based on whether or not the UE is transmitting or receiving on one of the virtual channels of interest to the UE;

detecting occurrence of an event effecting service availability for the UE;

determining behavior of the UE based on the ACTIVE state of the UE and the occurrence of the event;

wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises a downlink path, wherein the first virtual channel supports media transmissions for a first application on the UE, wherein the ACTIVE state comprises the UE receiving on the downlink path, wherein the event comprises the UE receiving, from the serving cell, a command to execute a handover to a target cell,

the UE performing;

determining that the target cell does not support the first virtual channel;

when a second application that does not use the first virtual channel is running on the UE and exchanging information with the serving cell and has at least the same priority as the first application, executing the handover to the target cell and ceasing reception on the downlink path,

otherwise, ignoring the command to execute the handover to the target cell.

6. The method of claim 5, wherein a first virtual channel of the plurality of virtual channels of interest to the UE comprises a downlink path, wherein the first virtual channel supports media transmissions for a first application on the UE, wherein the ACTIVE state comprises instead the UE receiving on the downlink path, wherein the event comprises the UE determining that a time has arrived to send to the serving cell a radio frequency (RF) measurement report for another cell, the method further comprising:

the UE performing;

determining whether the other cell supports the first virtual channel;

when the other cell supports the first virtual channel, sending the RF measurement report for the other cell;

when the other cell does not support the first virtual channel, and a second application that does not use the first virtual channel is running on the UE and exchanging information with the serving cell and has at least the same priority as the first application, sending the RF measurement report for the other cell;

otherwise, withholding sending the RF measurement report for the other cell.

7. A method for mobility management of user equipment (UE) in a long term evolution (LTE) system, the method comprising:

the UE performing;

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

detecting occurrence of an event effecting service availability for the UE;

determining behavior of the UE based on the state of the UE and the occurrence of the event;

when UE is in an ACTIVE state and not transmitting or receiving on any of its virtual channels of interest, and the UE receives, from the serving cell, a command to execute a handover to a target cell, the UE performing;

determining whether the target cell supports any virtual channel in the plurality of virtual channels of interest to the UE;

when the target cell supports a virtual channel in the plurality of virtual channels of interest to the UE, executing the handover to the target cell;

when the target cell does not support any of the virtual channels in the plurality of virtual channels of interest to the UE, but an application that does not use any of the virtual channels of interest to the UE is running on the UE and exchanging information with the serving cell, executing the handover to the target cell;

otherwise, ignoring the command to execute the handover to the target cell.

8. The method of claim 7 further comprising:

when the UE is in the ACTIVE state and the UE is not transmitting or receiving on any of its virtual channels of interest, when the UE determines that a time has arrived to send to the serving cell a radio frequency (RF) measurement report for another cell;

the UE performing;

determining whether the other cell supports any virtual channel in the plurality of virtual channels of interest to the UE;

when the other cell supports a virtual channel in the plurality of virtual channels of interest to the UE, sending the RF measurement report for the other cell;

when the other cell does not support any of the virtual channels in the plurality of virtual channels of interest to the UE, and an application that does not use any of the virtual channels of interest to the UE is running on the UE and exchanging information with the serving cell, sending the RF measurement report for the other cell;

otherwise, withholding sending the RF measurement report for the other cell.

9. The method of claim 7 further comprising:

when the UE in an IDLE state, the UE performing;

determining a list of cells, wherein each cell in the list supports at least one virtual channel of interest to the UE;

determining a candidate subset of the list of cells, wherein each cell in the subset is a candidate for becoming a serving cell, wherein inclusion in the candidate subset is based on whether or not the UE is receiving on a downlink path of one of the virtual channels of interest to the UE;

selecting one of the cells in the candidate subset as a target cell.

10. The method of claim 9 further comprising prioritizing the cells in the candidate subset into a preferred selection order.

11. The method of claim 10, wherein the prioritizing is based on signal strength of each cell in the candidate subset.

12. The method of claim 10, wherein the prioritizing is based on a number of virtual channels of interest supported by each cell in the candidate subset.

13. The method of claim 9, wherein determining the list of cells comprises building the list of cells by scanning a common point-to-multipoint channel of a cell in which the UE is currently located and a common point-to-multipoint channel of at least one neighboring cell having a signal strength above a minimum threshold.

14. The method of claim 9, wherein the UE is receiving on a downlink path of a first virtual channel of interest, wherein determining the candidate subset comprises determining all cells from the list of cells that support the downlink path of the first virtual channel and that have a signal strength above a minimum threshold.

15. The method of claim 14, when the candidate subset is initially null, determining a subsequent candidate set by determining all cells from the list of cells having a signal strength above a minimum threshold.

16. The method of claim 9, wherein the UE is not receiving on a downlink path of any of the virtual channels of interest, wherein determining the candidate subset comprises selecting cells from the list of cells that have a signal strength above a minimum threshold.