Method and apparatus for searching for network

• US 9,313,726 B2
• Filed: 10/24/2014
• Issued: 04/12/2016
• Est. Priority Date: 09/29/2013
• Status: Active Grant

• Current Assignee: Huawei Device Company Limited (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Device Company Limited (Huawei Investment & Holding Co., Ltd.)
• Inventors: Dang, Shujun, Duan, Xiaoyan, Jin, Hui, Wang, Jian, Chen, Xiaoyan, Jiang, Yinqing, Fa, Yongtao, Liu, Xiaojian
• Primary Examiner(s): Flores, Leon
• Application Number:
  US14/523,543
• Publication Number:
  US 20150094058A1
• Time in Patent Office: 536 Days
• Field of Search: 455/434, 455/435.1
• US Class Current: 1/1
• CPC Class Codes: H04W 48/02 Access restriction performed under specific conditions
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems

Abstract

The present invention discloses a method and an apparatus for searching for a network. The method includes: determining that a user equipment (UE) camping on a cell of a current public land mobile network (PLMN) is in an access barred state; determining that the UE cannot be successfully registered with the current PLMN; and performing a PLMN search. In the method and the apparatus for searching for a network according to embodiments of the present invention, if it is determined that the UE normally camping on the cell of the current PLMN is in the access barred state and cannot be successfully registered with the current PLMN, the PLMN search is performed, so that when the UE is in the access barred state, the UE can still perform the PLMN search, and can further select a new PLMN for access and execute a normal service, thereby improving user experience.

Claims

1. A method for searching for a network, the method comprising:

at a user equipment (UE) camping on a cell of a current public land mobile network (PLMN);

in response to determining that the UE is in an access barred state in the camped cell, and that the UE cannot be successfully registered with the current PLMN, determining whether the current PLMN is a normal PLMN, wherein the normal PLMN comprises;

a registered public land mobile network (RPLMN) with which the UE is previously successfully registered, a home public land mobile network (HPLMN) of the UE or an equivalent home public land mobile network (EHPLMN) of the UE;

performing a PLMN search in response to the UE determining that the current PLMN is not the normal PLMN; and

reselecting a cell in the current PLMN in response to the UE determining that the current PLMN is the normal PLMN.

2. The method according to claim 1, wherein performing the PLMN search comprises:

performing the PLMN search by using a manner in which a shortest PLMN search period is used as a start point and a PLMN search period is gradually extended, wherein the shortest PLMN search period is shorter than a PLMN search period that is used when the UE can execute a normal service;

or

performing the PLMN search by using a search period shorter than a PLMN search period that is used when the UE can execute a normal service.

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

if the UE cannot send a location registration request to the current PLMN, determining that the UE cannot be successfully registered with the current PLMN;

or

if the current PLMN rejects a location registration request sent by the UE, determining that the UE cannot be successfully registered with the current PLMN.

4. A method for searching for a network, comprising:

in a user equipment (UE) camping on a cell of a current public land mobile network (PLMN);

determining whether the UE is in an access barred state in the camped cell;

in response to the UE being in the access barred state in the camped cell, determining whether the current PLMN is a home public land mobile network HPLMN of the UE, whether the PLMN is an equivalent home public land mobile network EHPLMN of the UE, and whether the UE is in a normal state;

switching to a limited service state and performing a PLMN search if the current PLMN is neither the HPLMN of the UE nor the EHPLMN of the UE, and the UE is not in the normal roaming state; and

reselecting a cell in the current PLMN if the current PLMN is the HPLMN or current PLMN is the EHPLMN, or the UE is in the normal roaming state.

5. The method according to claim 4, wherein performing the PLMN search comprises:

performing the PLMN search by using a manner in which a shortest PLMN search period is used as a start point and a PLMN search period is gradually extended, wherein the shortest PLMN search period is shorter than a PLMN search period that is used when the UE can execute a normal service;

or

performing the PLMN search by using a search period shorter than a PLMN search period that is used when the UE can execute a normal service.

6. The method according to claim 4, wherein determining whether the UE is in a normal roaming state comprises:

determining that the UE is not in the normal roaming state if at least one of the following cases exists;

the UE cannot be successfully registered with the current PLMN, the current PLMN is not a registered public land mobile network RPLMN with which the UE is previously successfully registered, a PLMN selector list of the UE does not comprise the current PLMN, the UE is not in a roaming state, roaming configuration information of the UE does not comprise information about the current PLMN, or a network type of the current PLMN is not a type of a network in which the UE can normally roam.

7. A terminal device for searching for a network, comprising a processor and a memory storing instructions, the instructions being executable by the processor to cause the terminal device to:

camp on a cell of a current public land mobile network (PLMN);

determine whether the current PLMN is a normal PLMN in response to determining that the terminal device is in an access barred state in the camped cell, and that the terminal device cannot be successfully registered with the current PLMN, wherein the normal PLMN comprises;

a registered public land mobile network (RPLMN) with which the terminal device is previously successfully registered, a home public land mobile network (HPLMN) of the terminal device or an equivalent home public land mobile network (EHPLMN) of the terminal device;

perform a PLMN search in response to the terminal device determining that the current PLMN is not the normal PLMN; and

reselect a cell in the current PLMN if the terminal device determines that the current PLMN is the normal PLMN.

8. The terminal device according to claim 7, wherein the instructions are further executable by the processor to cause the terminal device to:

perform the PLMN search by using a manner in which a shortest PLMN search period is used as a start point and a PLMN search period is gradually extended, wherein the shortest PLMN search period is shorter than a PLMN search period that is used when the terminal device can execute a normal service;

or

perform the PLMN search by using a search period shorter than a PLMN search period that is used when the terminal device can execute a normal service.

9. The terminal device according to claim 7, wherein the instructions are further executable by the processor to cause the terminal device to:

determine that the terminal device cannot be successfully registered with the current PLMN if the terminal device cannot send a location registration request to the current PLMN;

or

determine that the terminal device cannot be successfully registered with the current PLMN if the current PLMN rejects a location registration request sent by the terminal device.

10. A terminal device for searching for a network, comprising a processor and a memory storing instructions, the instructions being executable by the processor to cause the terminal device to:

camp on a cell of a current public land mobile network (PLMN);

determine whether the terminal device is in an access barred state in the camped cell;

in response to the terminal device being in the access barred state in the camped cell, determine whether the current PLMN is a home public land mobile network HPLMN of the terminal device, whether the PLMN is an equivalent home public land mobile network EHPLMN of the terminal device, and whether the terminal device is in a normal state;

switch to a limited service state and perform a PLMN search if the current PLMN is neither the HPLMN of the terminal device nor the EHPLMN of the terminal device, and the terminal device is not in the normal roaming state; and

reselect a cell in the current PLMN if the current PLMN is the HPLMN or current PLMN is the EHPLMN, or the terminal device is in the normal roaming state.

11. The terminal device according to claim 10, wherein the instructions are further executable by the processor to cause the terminal device to:

perform the PLMN search by using a manner in which a shortest PLMN search period is used as a start point and a PLMN search period is gradually extended, wherein the shortest PLMN search period is shorter than a PLMN search period that is used when the terminal device can execute a normal service;

or

perform the PLMN search by using a search period shorter than a PLMN search period that is used when the terminal device can execute a normal service.

12. The terminal device according to claim 10, wherein the instructions are further executable by the processor to cause the terminal device to:

determine that the terminal device is not in the normal roaming state if at least one of the following cases exists;

the terminal device cannot be successfully registered with the current PLMN, the current PLMN is not a registered public land mobile network RPLMN with which the terminal device is previously successfully registered, a PLMN selector list of the terminal device does not comprise the current PLMN, the terminal device is not in a roaming state, roaming configuration information of the terminal device does not comprise information about the current PLMN, or a network type of the current PLMN is not a type of a network in which the terminal device can normally roam.