DESC:FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

SYSTEM AND METHOD FOR ENABLING A PUBLIC LAND MOBILE NETWORK (PLMN) SELECTION DURING CHANGE IN A LOCATION OF A USER DEVICE

SAMSUNG R&D INSTITUTE INDIA – BANGALORE PRIVATE LIMITED,
#2870, Orion Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanekundi Circle,
Marathahalli Post, Bangalore – 560037,
Karnataka, India,
an Indian Company

The following Specification particularly describes the invention and the manner in which it is to be performed

RELATED APPLICATION

The present invention claims benefit of the Indian Provisional Application No. 4078/CHE/2015 titled “METHOD FOR QUICK SERVICE USING NEW METHODS” by Samsung R&D Institute India – Bangalore Private Limited, filed on 5th August 2015, which is herein incorporated in its entirety by reference for all purposes.

FIELD OF THE INVENTION

The present invention generally relates to wireless devices and more particularly relates to a system and method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of a user device.

BACKGROUND OF THE INVENTION

When a user equipment (UE) is powered on in new location or moves between different telecom circles, legacy behavior of the UE takes considerable amount of time to camp on a Network. With the technology revolution, it has become imperative for service providers and UE manufacturers to give user with a method using which the UE can quickly latch on to the network.

Figure 1 is a schematic diagram 100 illustrating a process of camping on a network while moving to new location, according to an existing art. According to the Figure 1, a user with user equipment (UE) 102 is travelling from his home network to a roaming network (Ex: across State/Country boundaries) or vice-versa, wherein the user is moving from city A 104, registered on public land mobile network (PLMN)-A, and moving to city B 106. It takes quite some time for the UE 102 to register onto the network that can provide service, as the new PLMN in city B 106 are not known and the UE 102 has to scan all the frequencies it supports on which it can possibly find service. The full network scan takes quite some time depending on the Radio Access Technology (RAT) that UE 102 supports. Also, not only this precipitates a bad user experience, including cases where user might perform full manual scan, it also takes a toll on the battery life and eventually affects the UE’s 102 performance. With the advent of technology and more people travelling across places, this becomes a crucial problem entailing bad user experience.

Traditionally as per 3GPP specification, whenever the UE is powered on, it needs to search for last Registered PLMN (RPLMN) on the available RATs. Typically, full band search on RPLMN for all the RATs typically take around 1.5 minutes. Whenever UE moves from one telecom circle to another telecom circle, the UE faces the problem of slow acquisition at boot-up. The UE unnecessary scans full band on RPLMN even though RPLMN is not present. Finally, it takes 2 to 3 Minutes for the UE to acquire service if user goes to a new telecom circle every time.

The root cause of the current UE behavior is that the UE location is uncertain in this case. The UE doesn’t know that RPLMN is available at the current moment or not. Thus, the user faces delayed service especially during frequent travel. Further, the user faces unnecessary scan of last visited network, un-optimized algorithm for both domestic and international market, poor user experience, need for manual search and thus consuming more time, and therefore leading to battery draining.

Thus, there is need for a method for quick Service using new methods that can provide optimized method for both domestic and international market, better user experience, and thus avoid unnecessary scan of network, thereby reducing batter drain.

The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

SUMMARY OF THE INVENTION

The various embodiments of the present invention disclose a system and method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE). The present invention provides optimized performance in cases where user changes its location from last registered public land mobile network (PLMN).

According to an embodiment of the present invention, a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of a user equipment (UE) comprises of performing, by the UE, an emergency camping on a first PLMN during a change in location of the UE from a first network to a second network in a power ON mode, detecting, by the UE, System Information Block (SIB) of the first PLMN during the emergency camping, identifying, by the UE, a Mobile Country Code (MCC) and a Mobile Network Code (MNC) of the first PLMN using detected SIB information, comparing, by the UE, the identified MCC and MNC of the first PLMN with a PLMN database to determine whether a Registered PLMN (RPLMN) of the UE is same as that of the first PLMN and selecting at least one second PLMN from a plurality of priority PLMNs of the second network from the PLMN database when the RPLMN is different from the first PLMN.

According to an embodiment of the present invention, the MCC and MNC are determined from the PLMN on which the UE camps during the auto camp mode. According to an embodiment of the present invention, the auto camp mode is a mode by which the UE detects a System Information Block (SIB) without camping so as to obtain location information of the UE.

According to an embodiment of the present invention the PLMN on which the UE avails full service in the second network area is determined based on a roaming agreement of a first network operator with a second network operator obtained from the PLMN database, wherein the PLMN database comprises details of a plurality of network areas associated with a plurality of network operators.

According to an embodiment of the present invention, a current location of the UE is used to determine a best match location of the UE in roaming mode and a corresponding PLMN for a home network operator.

According to an embodiment of the present invention, the PLMN database details comprises at least one of, but not limited to, MCC, MNC, network operator name, PLMN, user location, network area/telecom circle, roaming agreement with home network operator, and the like.

According to an embodiment of the present invention, the method further comprises step of updating the PLMN database, where the PLMN database is updated based on one of, but not limited to, over-the-air as and when a new network operator is added in a network region, when an existing network operator area is added, deleted or updated, when roaming agreements between the network operators are changed, when a new version of the SE13 (Maintain Technical Settings) Table is released, and the like.

According to an embodiment of the present invention, the method further comprises of exchanging, by a first SIM of a multi-SIM device, location information with a second SIM during the emergency camping in a multi-SIM device, where a network area derived from a first SIM card is used by a second SIM card.

According to an embodiment of the present invention, the first SIM is the SIM which gets the network service first during an auto camp on mode. According to another embodiment of the present invention, the user selects the SIM for enabling the PLMN service based on a priority.

According to an embodiment of the present invention, the network area refers to a country/sub region of a country. The terms network area and telecom circle are used interchangeably in the description herein.

In another embodiment of the present invention, a User Equipment (UE) arranged for operation in a multi-network cellular environment and arranged for a Public Land Mobile Network (PLMN) selection subsequent to a change in location, comprises of one or more subscriber identity modules (SIMs) for accessing one or more corresponding PLMNs in a respective location, a storage unit comprising a PLMN database, where the PLMN database is adapted to store one or more PLMN lists, and
a processor for enabling the PLMN selection adapted for performing steps of enabling an auto camp mode on a first available network during a change in location of the user equipment (UE) from a first network to a second network in a power ON mode, determining the PLMN on which the UE can get a full service in auto camp mode, identifying a Mobile Country Code (MCC) and a Mobile Network Code (MNC) from the PLMN on which the UE performs emergency camping during the auto camp mode, comparing the identified MCC and MNC with a PLMN database to determine whether the Telecom circle of the Registered PLMN (RPLMN) of the UEis same as that of detected MCC and MNC Telecom circle, and selecting at least one priority PLMN from a plurality of PLMNs for the identified second network area from a PLMN database if the RPLMN is different.

According to an embodiment of the present invention, the PLMN is at least one of a Home Public Land Mobile Network (PLMN), an equivalent HPLMN or any PLMN having a higher priority than a currently selected network.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a schematic flow diagram illustrating a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE), according to an embodiment of the present invention.

Figure 2 is a schematic diagram illustrating a use case for a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE), according to an embodiment of the present invention.

Figure 3 is a block diagram illustrating a mobile communication device in accordance with an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The various embodiments of the present invention disclose a system and method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE). In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The present invention provides a system and method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of a user equipment (UE). The person having ordinarily skilled in the art can understand that the described embodiments use cases are for better understanding and illustration of the present invention, but not limit to scope of the present invention. The embodiments of the present invention are described with respect to user equipment (UE) that can be any of electronic devices such as, but not limited to, mobile phone, tablet, PDA, smart watch, and the like, and the person having ordinarily skilled in the art can understand that any of the electronic device with communication capabilities can be used, without departing from the scope of the invention.

According to an embodiment of the present invention, a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE) is described herein. According to the present invention, the method comprises step of performing, by the user equipment (UE), an emergency camping on a first available network during a change in location of the user equipment (UE) from a first network to a second network in a power ON mode. A user of the UE moves from one location to another location. Currently, the UE is camped on the first network in first location. As the user of the UE moves to another location out of the coverage region of the network, the UE need to camp on another network for accessing services. Therefore, as soon as the UE moves to another location, during power ON mode, the UE performs emergency camping on the first available network. In an embodiment of the present invention, the first available network can be a public land mobile network (PLMN), without departing from the scope of the present invention.

Further, the method comprises step of determining the PLMN on which the UE can get a full service in auto camp mode. As soon the UE performs emergency camping and camped on the first available network, the UE starts searching all the public land mobile networks (PLMNs) for the available PLMN on which the UE can access the full service.

Further, the method comprises step of identifying, by the user equipment (UE), a Mobile Country Code (MCC) and a Mobile Network Code (MNC) from the PLMN on which the UE performs emergency camping. To complete the auto-camping, the UE accesses the information associated with the first available network or the PLMN on which the UE has performed emergency camping, and obtains Mobile Country Code (MCC) and a Mobile Network Code (MNC). In an embodiment of the present invention, the MCC and MNC are determined from the network on which the UE camps during emergency mode. In another embodiment of the present invention, the PLMN on which the UE avails full service in the second network area is determined based on a roaming agreement of the first network operator with the second network operator obtained from the PLMN database, without departing from the scope of the present invention.

Further, the method comprises step of comparing the identified MCC and MNC with a PLMN database to determine whether a Registered PLMN of the network area in auto camp mode of the UE is same as that of detected MCC and MNC. In an embodiment of the present invention, a current location of the UE is used to determine a best match location of the UE in roaming mode and a corresponding PLMN for a home network operator. Based on the identified MCC and MNC, the UE checks and compares the PLMN database to determine whether the registered PLMN of the network area in auto camp mode of the UE is same as that of detected MCC and MNC.

In an embodiment of the present invention, the PLMN database comprises details of a plurality of network areas associated with a plurality of network operators. In an embodiment of the present invention, the PLMN database details comprises at least one of, but not limited to, MCC, MNC, network operator name, PLMN, user location, roaming agreement between the network operators and network operator, and the like, without departing from the scope of the invention. In another embodiment of the present invention, the PLMN database can be present at the UE end and the database gets updated every time the UE camps on new PLMN. The person having ordinarily skilled in the art can understand how the UE accesses the PLMN database and obtains information related to the PLMNs, without departing from the scope of the invention.

In an embodiment of the present invention, the PLMN database can be enhanced in conjunction with either operator controlled PLMN (OPLMN) or user controlled PLMN (UPLMN) list so as to select the best PLMN match in the new location.

In an embodiment of the present invention, the PLMN database can be stored in storage units of the UE such as, but not limited to, SIM, external memory card, encrypting file system (efs) files, flat file, source code, and the like. . In another embodiment of the present invention, the PLMN database can be stored in external servers from where it can be downloaded onto the user equipment. The person having ordinarily skilled in the art can understand that the PLMN database can be stored in any of the known storage units from where the UE can access the PLMN database and obtain necessary PLMN information, without departing from the scope of the invention.

In another embodiment of the present invention, the PLMN database stored in the user equipment can be manually updated by the user. In yet another embodiment of the present invention, the PLMN database stored in the device can be updated based on previous network reselection data.

Further, the method comprises step of selecting at least one priority PLMN from a plurality of PLMNs for the identified second network area from the PLMN database if a registered PLMN (RPLMN) is different. Based on the checking and comparison, the UE can identify which PLMN is suitable for camping and can be selected as the registered PLMN (RPLMN). During checking and comparison, if the UE identifies that the RPLMN is different than suitable PLMN, then the UE selects at least one priority PLMN from the plurality of PLMNs for the identified second network area from the PLMN database.

In an embodiment of the present invention, the method further comprises steps of updating the PLMN database, where the PLMN database is updated based on at least one of, but not limited to, Over-The-Air as and when a new network operator is added in a network region, when an existing network operator area is added, deleted or updated, when roaming agreements between the network operators are changed, when a new version of the SE13 (Maintain Technical Settings) Table is released, and the like, without departing from the scope of the invention.

In another embodiment of the present invention, in case of multi SIM UE, the method further comprises steps of exchanging, by a first SIM of a multi-SIM UE, location information with a second SIM during a quick camping in the multi-SIM UE, wherein a network area derived from a first SIM card is used by a second SIM card. In another embodiment of the present invention, the first SIM is the SIM which gets the network service first during an auto camp on mode, without departing from the scope of the invention.

In an embodiment of the present invention, in the Multi SIM UE, the user can select the SIM on which the service needs to be attained on priority, wherein the selection of the SIM to get first service can be with the Subscription where the number of bands/RAT support is minimum. In an embodiment of the present invention, if one SIM is in HOME operator coverage and other SIM is in Roaming coverage then the preference shall be given to the HOME SIM selection.

The present method for enabling a Public Land Mobile Network (PLMN) selection of user equipment (UE) is triggered during, but not limited to, UE power up, the Airplane mode in turned OFF, the UE comes to in-service from Out of service (OOS) area, manual selection by the user, manual selection by the user by selecting the telecom circle via a UI, the user goes from one telecom circle to another, and the like.

Figure 1 is a schematic flow diagram 100 illustrating a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE), according to an embodiment of the present invention. According to the flow diagram 100, at step 102, the user equipment (UE) performs an emergency camping on a first available network during a change in location of the user equipment from a first network to a second network in a power ON mode. At step 104, the UE determines the PLMN on which the UE can get a full service in auto-camp mode.

Further, at step 106, the UE identifies a Mobile Country Code (MCC) and a Mobile Network Code (MNC) from the PLMN on which the UE performs emergency camping. At step 108, the UE compares the identified MCC and MNC with a PLMN database to determine whether a Registered PLMN of the network area in auto camp mode of the UE is same as that of detected MCC and MNC. Further, at step 110, the UE selects at least one priority PLMN from a plurality of PLMNs for the identified second network area from a PLMN database if the RPLMN is different.

Figure 2 is a schematic diagram 200 illustrating a use case for a method for enabling a Public Land Mobile Network (PLMN) selection during change in a location of user equipment (UE), according to an embodiment of the present invention. According to the diagram 200, at step 202, the UE is powered on in a new location. In another embodiment of the present invention, the UE is already in powered on mode, without departing from the scope of the invention. At step 204, the UE uses any of the known technique to perform emergency auto-camp on the PLMN. During auto camping mode, the UE detects system information block (SIB) to identify and obtain information such as, but not limited to, mobile country code (MCC), mobile network code (MNC), and the like that are associated with the PLMN or registered PLMN (RPLMN) on which the UE has camped on emergency basis. The various information that the UE can obtain from the SIB is described herein above and thus not described again to avoid repetition.

Further, at step 206, the UE checks whether telecom circle of the RPLMN on which the UE has camped on is same as that of the detected MCC and MNC in auto-camp mode. If yes, then at step 208, the UE uses any of the known quality check (QC) method for checking the quality of the RPLMN. If no, then at step 210, the UE accesses PLMN database and derive available PLMNs in the current location. At step 212, the UE checks whether the derived PLMN is null. If yes, then the process moves to step 208, wherein the UE selects the PLMN as the RPLMN and uses any of the known quality check (QC) method for checking the quality of the RPLMN.

If no, then at step 214, a non-access stratum (NAS) sends PLMN selection request on derived PLMN from the PLMN database on radio access technology (RAT) on which the UE detected in auto-camp mode. At step 216, the UE checks whether the derived PLMN is found on camped RAT. If yes, then at step 218, the UE gets service and starts accessing services over the selected PLMN/ RPLMN. If no, then at step 220, the UE continues searching for the PLMN on other RATs. At step 222, the UE checks whether service is found on other RATs for PLMN. If yes, then the process moves to step 218 and UE gets service and starts accessing services over the selected PLMN/ RPLMN. If no, then at step 224, the UE continues trying for service on available PLMN list.

Figure 3 is a block diagram illustrating a mobile communication device/ user equipment (UE) 300 in accordance with an embodiment of the present invention. According to the block diagram, the UE 300 comprises of two subscriber identity modules (SIMs) SIM1 302a and SIM2 302b, a communication unit 304, a processor 306, and a storage unit 308, wherein the storage unit 308 comprises of a PLMN database 310.

In the present embodiment, the UE 300 is a dual SIM device with two SIMs, SIM1 302a and SIM2 302b and can access two same or different networks. The SIMs, SIM1 302a and SIM2 302b attempt to camp on the PLMN, and transmit and receive signals within the coverage of the PLMN. In another embodiment of the present invention, the UE 300 can be single SIM device. In another embodiment of the present invention, the UE 300 can be multi-SIM device with more than one SIMs with each SIM accessing same or different PLMNs respectively, without departing from the scope of the invention.

Further, as soon as the UE 300 is moved to a new location, the processor 306 performs emergency camping on a first available network. In an embodiment of the present invention, the UE 300 is in power ON mode during moving to the new location. Further, the UE 300 comprises of the storage unit 308 that stores the PLMN database 310 and other information related to the UE 300, wherein the PLMN database 310 comprises details of a plurality of network areas associated with a plurality of network operators. In an embodiment of the present invention, the storage unit 308 can be at least one of the, but not limited to, SIM, external memory card, encrypting file system (efs) files, flat file, source code, and the like. In an embodiment of the present invention, the PLMN database 310 details comprises at least one of, but not limited to, MCC, MNC, network operator name, PLMN, user location, roaming agreement between the network operators and network operator, and the like.

Based on accessing the PLMN database 310 from the storage unit 308, the processor 306 determines a PLMN on which the UE can get a full service in auto camp mode, and identifies a Mobile Country Code (MCC) and a Mobile Network Code (MNC) from the PLMN on which the UE performs emergency camping. Further, the processor 306 compares the identified MCC and MNC with a PLMN database to determine whether a Registered PLMN of the network area in auto camp mode of the UE is same as that of detected MCC and MNC, and selects at least one priority PLMN from a plurality of PLMNs for the identified second network area from a PLMN database if the RPLMN is different.

The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Furthermore, the various devices, modules, and the like described herein may be enabled and operated using hardware circuitry, for example, complementary metal oxide semiconductor based logic circuitry, firmware, software and/or any combination of hardware, firmware, and/or software embodied in a machine readable medium. For example, the various electrical structure and methods may be embodied using transistors, logic gates, and electrical circuits, such as application specific integrated circuit.

Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.
,CLAIMS:CLAIMS

We Claim:
1. A method of enabling a Public Land Mobile Network (PLMN) selection during change in location of a user equipment (UE), the method comprising:
performing, by the UE, an emergency camping on a first PLMN during a change in location of the UE from a first network to a second network in a power ON mode;
detecting, by the UE, System Information Block (SIB) of the first PLMN during the emergency camping;
identifying, by the UE, a Mobile Country Code (MCC) and a Mobile Network Code (MNC) of the first PLMN using detected SIB information;;
comparing, by the UE, a network area of the identified MCC and MNC of the first PLMN with a PLMN database to determine whether a Registered PLMN (RPLMN) of the UE is same as that of the first PLMN network area; and
selecting at least one second PLMN from a plurality of priority PLMNs of the second network from the PLMN database when a network area of the RPLMN is different from the network area of the first PLMN.

2. The method of claim 1, wherein the emergency camping also includes an auto camp mode, where the auto camp mode is a mode by which the UE detects a System Information Block (SIB) without camping on a PLMN so as to obtain location information of the UE.

3. The method of claim 1, wherein the PLMN on which the UE avails full service in the second network is determined based on a roaming agreement of a second network operator with a home network operator obtained from the PLMN database.

4. The method of claim 1, wherein a current location of the UE is used to determine a best match location of the UE in roaming mode and a corresponding PLMN for a home network operator.

5. The method of claim 1, wherein the PLMN database comprises details of a plurality of network areas associated with a plurality of network operators.

6. The method of claim 2, wherein the PLMN database details comprises at least one of MCC, MNC, network operator name, PLMN, user location, network area and roaming agreement with home network operator.

7. The method of claim 1, wherein further comprising updating the PLMN database, where the PLMN database is updated based on one of:
Over-The-Air as and when a new network operator is added in a network region;
when an existing network operator area is added, deleted or updated;
when roaming agreements between the network operators are changed; and
when a new version of the SE13 (Maintain Technical Settings) Table is released.

8. The method of claim 1, further comprises of:
exchanging, by a first SIM of a multi-SIM device, a location information with a second SIM during the emergency camping in a multi-SIM device, where a network area derived from a first SIM card is used by a second SIM card.

9. The method of claim 8, wherein the first SIM is the SIM which gets the network service first during an auto camp on mode.

10. The method of claim 1, wherein the user selects the SIM for enabling the PLMN service based on a priority.

11. A User Equipment (UE) arranged for operation in a multi-network cellular environment and arranged for a Public Land Mobile Network (PLMN) selection subsequent to a change in location, comprises of:
one or more subscriber identity modules (SIMs) for accessing one or more corresponding PLMNs in a respective location;
a storage unit comprising a PLMN database, where the PLMN database is adapted to store one or more PLMN lists; and
a processor for enabling the PLMN selection adapted for performing steps of:
performing an emergency camping on a first PLMN during a change in location of the UE from a first network to a second network in a power ON mode;
detecting System Information Block (SIB) of the first PLMN during the emergency camping;
identifying a Mobile Country Code (MCC) and a Mobile Network Code (MNC) of the first PLMN using detected SIB information;;
comparing a network area of the identified MCC and MNC of the first PLMN with a PLMN database to determine whether the Registered PLMN (RPLMN) network area of the UE is same as that of the first PLMN network area; and
selecting at least one second PLMN from a plurality of priority PLMNs of the second network from the PLMN database when a network area of the RPLMN is different from a network area the first PLMN.