METHOD IN COMMUNICATION DEVICE FOR STARTING A CIRCUIT SWITCHED FALLBACK IN WIRELESS COMMUNICATION SYSTEM

• US 20170289860A1
• Filed: 09/26/2014
• Published: 10/05/2017
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: WANG, Xiaohui
• Granted Patent: US 10,349,316 B2
• Time in Patent Office: Days
• 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 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/087 between radio units of access points
• CPC Class Codes: H04W 80/10 adapted for application session management, e.g. SIP [Session Initiation Protocol] connection management H04W76/00; arrangements for session management H04L67/14

Abstract

A method in a wireless communication device for starting a Circuit Switched FallBack, CSFB, in a wireless communication system is disclosed. The wireless communication system comprises one or more Long-Term Evolution, LTE, networks and one or more 2nd or 3rd Generation, 2G/3G, networks. When the communication device is camping in an LTE network and starts a Circuit Switched, CS, service, the wireless communication device sends a CSFB request to a Mobility Management entity, MME, via an access node in the LTE network and starts a first timer and/or a first counter upon sending the CSFB request. When the first timer and/or the first counter is expired and no response to the CSFB request has been received from the LTE networks, it starts a cell search procedure in the 2G/3G networks and starts the CS service via a target cell selected by the cell search procedure in the 2G/3G networks.

Claims

1. A method in a wireless communication device for starting a Circuit Switched FallBack, CSFB, in a wireless communication system, wherein the wireless communication system comprises one or more Long-Term Evolution, LTE, networks and one or more 2nd or 3rd Generation, 2G/3G, networks, and wherein the wireless communication device is camping in an LTE network, the method comprising:

sending a CSFB request to a Mobility Management entity, MME, via an access node in the LTE network;

starting a first timer and/or a first counter upon sending the CSFB request;

when the first timer and/or the first counter is expired and no response to the CSFB request has been received from the LTE network,

starting a cell search procedure in the 2G/3G networks; and

starting a Circuit Switched, CS, service via a target cell selected by the cell search procedure in the 2G/3G networks.

2. The method according to claim 1, wherein the method further comprises:

waiting for a condition to be fulfilled, wherein the condition to be fulfilled comprises one out of;

receiving a response from the MME via the access node in the LTE network, the first timer is expired, or the first counter is expired.

3. The method according to claim 2, wherein the first counter is set to a pre-defined number of CSFB requests, and wherein waiting for a condition to be fulfilled comprises:

checking if a response to the CSFB request has been received from the LTE network;

when no response to the CSFB request has been received from the LTE network,

sending a new CSFB request to the MME via the access node in the LTE Network;

decreasing the first counter by 1;

repeating steps checking, sending and decreasing until the first counter is expired.

4. A wireless communication device for starting a Circuit Switched FallBack, CSFB, in a wireless communication system, wherein the wireless communication system comprises one or more Long-Term Evolution, LTE, networks and one or more 2nd or 3rd Generation, 2G/3G, networks, and wherein the communication device is camping in an LTE network, the wireless communication device is configured to:

send a CSFB request to a Mobility Management entity, MME, via an access node in the LTE network;

start a first timer and/or a first counter upon sending the CSFB request;

when the first timer and/or the first counter is expired and no response to the CSFB request has been received from the LTE network,

start a cell search procedure in the 2G/3G networks; and

start a Circuit Switched, CS, service via a target cell selected by the cell search procedure in the 2G/3G networks.

5. The wireless communication device according to claim 4, wherein the wireless communication device is further configured to:

wait for a condition to be fulfilled, wherein the condition to be fulfilled comprises one out of;

receiving a response from the MME via the access node in the LTE network, the first timer is expired, or the first counter is expired.

6. The wireless communication device according to claim 5, wherein the first counter is set to a pre-defined number of CSFB requests, and wherein the wireless communication device is further configured to:

check if a response to the CSFB request has been received from the LTE network;

when no response to the CSFB request has been received from the LTE network,

send a new CSFB request to the MME via the access node in the LTE Network;

decrease the first counter by 1; and

repeat above checking, sending and decreasing actions until the first counter is expired.