Technique for Terminating Call Set Up in a CSFB Situation

• US 20130288671A1
• Filed: 05/23/2011
• Published: 10/31/2013
• Est. Priority Date: 10/05/2010
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Keller, Ralf, Ranke, Karl-Peter, Witzel, Andreas
• Granted Patent: US 9,538,574 B2
• Time in Patent Office: Days
• US Class Current: 455/433
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/00224 between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 76/18 Management of setup rejection or failure
• CPC Class Codes: H04W 76/19 Connection re-establishment
• CPC Class Codes: H04W 76/30 Connection release
• CPC Class Codes: H04W 8/02 Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
• CPC Class Codes: H04W 8/08 Mobility data transfer

Abstract

A technique for controlling set up of a terminating call to a UE in a CSFB situation involving a first MSC paging the UE and a second MSC where the UE is performing a Location Update is described. A method implementation of this technique comprises receiving, from an HLR, a PRN message and forwarding information received in the PRN message to the second MSC.

Claims

1. A method of controlling set up of a terminating call to a User Equipment, UE, in a Circuit Switched Fallback, CSFB, situation involving a first Mobile Switching Center, MSC, paging the UE and a second MSC where the UE is performing a Location Update, the method being performed by the first MSC and comprising:

receiving, from a Home Location Register, HLR, a Provide Roaming Number, PRN, message;

receiving, from a Gateway MSC, GMSC, a call set up request message;

receiving a notification message from the second MSC, the notification message triggering an enhanced Roaming Retry procedure to the first MSC;

forwarding information received in the PRN message towards the second MSC; and

forwarding the call set up request message towards the second MSC.

2. The method of claim 1, wherein the notification message is received during a Location Update procedure.

3. The method of claim 1, wherein the enhanced Roaming Retry procedure includes the forwarding of the information received in the PRN message towards the second MSC.

4. The method of claim 1, wherein the information received in the PRN message that is forwarded towards the second MSC includes the MSC number of the first MSC.

5. The method of claim 1, further comprising paging the UE in response to receipt of the call set up request message.

6. The method of claim 1, further comprising starting a paging timer and stopping the paging timer in response to receipt of a Cancel Location message from the HLR.

7. The method of claim 1, wherein the first MSC has aServing Gateways, SGs, interface association with a Mobility Management Entity, MME for the UE.

8. The method of claim 1, wherein the second MSC has no Serving Gateways, SGs, interface association with a Mobility Management Entity, MME for the UE.

9. The method of claim 1, wherein the UE is camping on at least one of a second generation, 2G cell and third generation, 3G cell not served by the first MSC.

10. The method of claim 1, wherein the second MSC is different from the first MSC.

11. A method of handling set up of a terminating call to a User Equipment, UE, in a Circuit Switched Fallback, CSFB, situation involving a first Mobile Switching Center, MSC, paging the UE and a second MSC where the UE is performing a Location Update, the method being performed by the second MSC and comprising:

triggering an enhanced Roaming Retry procedure to the first MSC;

receiving, from the first MSC, Provide Roaming Number, PRN, information;

receiving, from the first MSC, a call set up request message; and

handling call setup to the UE in accordance with the PRN information.

15. The method of claim 11, wherein the triggering is responsive to the presence of the CSMT flag in the Location Update message.

16. The method of claim 11, wherein triggering the enhanced Roaming Retry procedure to the first MSC comprises sending a notification message towards the first MSC.

17. The method of claim 16, wherein the notification message is sent during a Location Update procedure.

18. A computer program product comprising program code portions for performing the method of claim 11, when the computer program product is executed on a computing device.

19. The computer program product of claim 18, stored on a computer-readable recording medium.

12. The method of claim 12, further comprising receiving a Location Update message from the UE.

13. The method of claim 12, wherein the Location Update message includes a Circuit Switched Mobile Terminating, CSMT, flag.

14. The method of claim 13, wherein the CSMT flag indicates to the second MSC that the Location Update is due to CSFB.

20. A Mobile Switching Center, MSC, for controlling set up of a terminating call to a User Equipment, UE, in a Circuit Switched Fallback, CSFB, situation involving another MSC adapted to perform a Location Update procedure with the UE, the MSC being adapted to page the UE and comprising:

a receiving component adapted to;

receive, from a Home Location Register, HLR, a Provide Roaming Number, PRN, message,

receive, from a Gateway MSC, GMSC, a call set up request message,

receive a notification message from the second MSC, the notification message triggering an enhanced Roaming Retry procedure to the first MSC; and

a forwarding component adapted to;

forward information received in the PRN message towards the other MSC, and

forward the call set up request message towards the second MSC.

21. A Mobile Switching Center, MSC, for handling set up of a terminating call to a User Equipment, UE, in a Circuit Switched Fallback, CSFB, situation involving another MSC paging the UE, the MSC being adapted to perform a Location Update procedure with the UE and comprising:

a triggering component adapted to trigger an enhanced Roaming Retry procedure to the first MSC;

a receiving component adapted to receive, from the other MSC, Provide Roaming Number, PRN, information and further adapted to receive, from the other MSC, a call set up request message; and

a handling component adapted to handle call set up to the UE in accordance with the PRN information.