FAST WIFI TO LTE HANDOVER

• US 20160080981A1
• Filed: 09/11/2014
• Published: 03/17/2016
• Est. Priority Date: 09/11/2014
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: WANG, Chunbo, Nilsson, Daniel, Olsson, Lars-Bertil, Rommer, Stefan
• Granted Patent: US 9,497,667 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface

Abstract

The present invention relates to a network node and a method at the network node of handing over a mobile terminal between a first RAT and a second RAT in a wireless communications network. The invention further relates to a computer program performing the method according to the present invention, and a computer program product comprising computer readable medium having the computer program embodied therein.

A method at a network node of a packet core network of performing handover of a mobile terminal between a first Radio Access Technology (RAT), and a second RAT in a wireless communications network is provided in an embodiment of the present invention. The method comprises receiving a request for handover of the mobile terminal to the second RAT, establishing a PDN connection with the mobile terminal via the first RAT, and performing handover of the mobile terminal to the second RAT. The method further comprises maintaining PDN connection context for the PDN connection established via the first RAT for a time period, and releasing the PDN connection context at expiry of the time period.

Claims

1. A method by at least one network node of a packet core network of performing handover of a mobile terminal between a first Radio Access Technology, RAT, and a second RAT in a wireless communications system, comprising:

establishing a Packet Data Network, PDN, connection with the mobile terminal via the first RAT;

receiving a request for handover of the mobile terminal to the second RAT;

performing handover of the mobile terminal to the second RAT;

maintaining PDN connection context for said PDN connection established via the first RAT for a time period; and

releasing the PDN connection context at expiry of said time period.

2. The method of claim 1, further comprising the steps of:

establishing a PDN connection with the mobile terminal via the second RAT;

receiving a request for handover of the mobile terminal to the first RAT;

determining whether the PDN connection context for said PDN connection established via the first RAT is still maintained; and

if so;

performing handover of the mobile terminal to the first RAT without performing update location with a Home Subscriber Server, HSS, and without creating a session with a Serving Gateway, SGW.

3. The method of claim 2, wherein the step of determining whether the PDN connection context for said PDN connection established via the first RAT is still maintained comprises:

determining whether said at least one network node has access to subscription data of the mobile terminal in accordance with the request for handover to the first RAT.

4. The method claim 1, wherein the request for handover from the second RAT to the first RAT comprises an attach request indicating handover and identifying the mobile terminal.

5. The method of claim 1, said at least one network node being any one or more selected from a group comprising a Mobility Management Entity, MME, a Serving Gateway, SGW, and a Packet Data Network Gateway, PGW, in a Long Term Evolution, LTE, network, a Serving General Packet Radio Service Support Node, SGSN, and a Gateway General Packet Radio Service Support Node, GGSN, in a Universal Mobile Telecommunication System, UMTS, network, a Serving General Packet Radio Service Support Node, SGSN, and a Gateway General Packet Radio Service Support Node, GGSN, in a Global System for Mobile communications, GSM, network.

6. The method of claim 5, wherein the maintaining of the PDN connection context with the first RAT for a time period comprises the MME or the SGSN, the SGW and the PGW interacting in maintaining the PDN connection context for said PDN connection established via the first RAT by exchanging delete bearer messages indicating handover from the first RAT to the second RAT, thereby storing the PDN context of the established PDN connection.

7. The method according to claim 5, wherein the SGW and the PGW are made aware of the request for handover from the second RAT to the first RAT by receiving a modify bearer request indicating the handover.

14. A computer program comprising computer-executable instructions for causing a device to perform steps recited in claim 1 when the computer-executable instructions are executed on a processing unit included in the device.

15. A computer program product comprising a computer readable medium, the computer readable medium having the computer program according to claim 14 embodied therein.

8. A first network node of a packet core network of performing handover of a mobile terminal between a first Radio Access Technology, RAT, and a second RAT in a wireless communications system, comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby said first network node is operative to:

establish a Packet Data Network, PDN, connection with the mobile terminal via the first RAT;

receive a request for handover of the mobile terminal to the second RAT;

perform handover of the mobile terminal to the second RAT;

maintain PDN connection context for said PDN connection established via the first RAT for a time period; and

release the PDN connection context at expiry of said time period.

9. The first network node of claim 8, said first network node being a Packet Data Network Gateway, PGW, in a Long Term Evolution, LTE, network.

10. A second network node communicating with the first network node of claim 8, comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby said second network node is operative to:

establish a PDN connection with the mobile terminal via the second RAT;

receive a request for handover of the mobile terminal to the first RAT;

determine whether the PDN connection context for said PDN connection established via the first RAT is still maintained; and

if so;

perform handover of the mobile terminal to the first RAT without performing update location with a Home Subscriber Server, HSS, and without creating a session with a Serving Gateway, SGW.

11. The second network node of claim 10, said second network node being any one selected from a group comprising a Mobility Management Entity, MME, in a Long Term Evolution, LTE, network, a Serving General Packet Radio Service Support Node, SGSN, in a Universal Mobile Telecommunication System, UMTS, and a Serving General Packet Radio Service Support Node, SGSN, in a Global System for Mobile communications, GSM, network.

12. The second network node claim 10, wherein the determining whether the PDN connection context for said PDN connection established via the first RAT is still maintained comprises determining whether said at least second network node has access to subscription data of the mobile terminal in accordance with the request for handover to the first RAT.

13. The second network node of claim 10, wherein the request for handover from the second RAT to the first RAT comprises an attach request indicating handover and identifying the mobile terminal.