Patent Description:
Electronic devices capable of performing cellular communication, such as a smartphone, a tablet personal computer (PC), a smart watch, and the like, are being developed.

As technology advances, various radio access technologies (hereinafter "RATs") for cellular communication are being introduced. Accordingly, electronic devices capable of performing communication using a plurality of RATs supported by a service provider are under development. Since different RATs use different radio frequency (RF) bands that do not overlap each other, an electronic device supporting a plurality of RATs may be configured to operate in the RF band of each RAT.

<CIT> discloses a wireless communication method wherein when restarted, back to a network coverage area, or accessing a PLMN after an offline mode is turned off, a wireless terminal chooses to access the PLMN using a RAT used last time or access the PLMN according to a RAT that is of the PLMN and that is with a higher priority.

In the case where an electronic device supporting a plurality of RATs attempts to search for a PLMN, the electronic device may have to search for all RF bands of the plurality of RATs supported by the electronic device in order to search for an available PLMN. However, if the PLMN supports only some RATs, instead of supporting all the RATs supported by the electronic device, the operation of searching for the PLMN on all of the RATs may cause unnecessary current consumption and an increase in searching time. Therefore, a method for reducing the current consumption of the electronic device and PLMN searching time may be required.

The technical subjects pursued in the disclosure may not be limited to the above mentioned technical subjects, and other technical subjects which are not mentioned may be clearly understood, through the following descriptions, by those skilled in the art to which the disclosure pertains.

An electronic device for searching for a PLMN and a method therefor according to various embodiments are able to enhance efficiency of resources consumed for searching for a PLMN by searching for a PLMN, based on information on RATs supported by the PLMN.

Advantageous effects obtainable from the disclosure may not be limited to the above mentioned effects, and other effects which are not mentioned may be clearly understood, through the following descriptions, by those skilled in the art to which the disclosure pertains.

In the following, the invention is best understood in view of figure <NUM>. The remaining embodiments, aspects and examples disclosed below are included for illustrative purposes and for facilitating the understanding of the invention.

Additionally, or alternatively, the auxiliary processor <NUM> may be adapted to consume less power than the main processor <NUM>, or to be specific to a specified function.

According to an embodiment, the interface <NUM> may include, for example, a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.

As used herein, each of such phrases as "A or B," "at least one of A and B," "at least one of A or B," "A, B, or C,"
"at least one of A, B, and C," and "at least one of A, B, or C," may include any one of, or all possible combinations of the items enumerated together in a corresponding one of the phrases. It is to be understood that if an element (e.g., a first element) is referred to, with or without the term "operatively" or "communicatively", as "coupled with, " "coupled to," "connected with," or "connected to" another element (e.g., a second element), it means that the element may be coupled with the other element directly (e.g., wiredly), wirelessly, or via a third element.

Alternatively, or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component.

<FIG> illustrates an example of a wireless communication network according to various embodiments.

Referring to <FIG>, a wireless communication network <NUM> may include public land mobile networks (PLMNs) <NUM> and <NUM>, base stations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and electronic devices <NUM> and <NUM>. The electronic devices may be the electronic device <NUM> and the electronic device <NUM> shown in <FIG>.

In various embodiments, the wireless communication network <NUM> may include one or more PLMNs <NUM> and <NUM>. Although it is shown that the PLMNs <NUM> and <NUM> do not overlap each other, in general, a plurality of PLMNs may overlap each other in various geographic areas.

In various embodiments, each of the PLMNs <NUM> and <NUM> may be identified by a unique PLMN identification (ID). The PLMN ID is information received through the base stations <NUM> to <NUM> such that the electronic devices <NUM> and <NUM> are able to distinguish between the PLMNs, and the PLMN ID may include mobile country code (MCC), mobile network code (MNC), location area identity (LAI), and PLMN operator identification code.

In various embodiments, the PLMNs <NUM> and <NUM> may provide cellular communication services to the electronic devices <NUM> and <NUM>, respectively, based on specific RATs. For example, the RATs supported by the PLMN may be <NUM>nd generation (<NUM>) RATs such as a global system for mobile communication (GSM), a general packet radio service (GPRS), enhanced data rates for GSM evolution (EDGE), and the like, <NUM>rd generation (<NUM>) RATs such as wideband code division multiplex access (WCDMA) and the like, <NUM>th generation (<NUM>) RATs such as long term evolution (LTE) and the like, <NUM>th generation (<NUM>) RATs, or the like. In various embodiments, one PLMN ID may provide services, based on a plurality of different RATs. For example, an example in which PLMN <NUM> (<NUM>) provides all cellular communication services of <NUM>, <NUM>, and <NUM> RAT standards is illustrated in <FIG>. In this case, as will be described later, the electronic device performing registration in a PLMN supporting a plurality of RATs may select one of the plurality of RATs supported by the PLMN within the limit supported by the electronic device, and may use communication services corresponding to the corresponding RAT standard.

The respective PLMNs <NUM> and <NUM> may communicate with one or more electronic devices <NUM> and <NUM> through one or more base stations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The respective base stations <NUM> to <NUM> may provide services to geographic areas that are able to be divided into one or more cells.

In various embodiments, in the case where the PLMN using the base stations supports a plurality of RATs, a plurality of different RAT networks may be provided to the same geographic area. For example, a plurality of RATs may be supported by one base station. For example, <FIG> shows an example in which one base station <NUM> provides services for all of <NUM>, <NUM>, and <NUM> networks. In general, when a plurality of RATs is deployed in the same geographic area, the frequency bands used by the respective RATs do not overlap each other.

In various embodiments, the respective base stations <NUM> to <NUM> may operate so as to transmit and receive information, signals, data, or messages to and from the electronic devices <NUM> and <NUM>. In various embodiments, the respective base stations <NUM> to <NUM> may periodically transmit system information messages to the electronic devices so as to enable the electronic devices <NUM> and <NUM> entering the service areas of the base stations to detect the base stations.

The electronic devices <NUM> and <NUM> may be devices that receive cellular communication services from the base stations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In various embodiments, the electronic devices <NUM> and <NUM> may perform a process of selecting one of the PLMNs <NUM> and <NUM> and performing registration therein in order to receive cellular communication services. In various embodiments, the electronic devices <NUM> and <NUM> may attempt to search for a PLML when the electronic devices are turned on or after recovering from the lack of coverage. The electronic devices <NUM> and <NUM> may search for available PLMNs using all supportable RF bands. The electronic devices <NUM> and <NUM> may search for a cell having maximum signal strength, may receive a system information message from the cell, and may extract information on available PLMNs from the system information message. If one or more available PLMNs are extracted from the system information message, the electronic devices <NUM> and <NUM> may select a PLMN therefrom according to priority. The priority for selecting the PLMN may be as follows:.

If the PLMN is selected according to the priority, the electronic devices <NUM> and <NUM> may perform cell selection and location registration therein.

Although it is illustrated in <FIG> that electronic device <NUM> (<NUM>) registers in PLMN <NUM> (<NUM>) and electronic device <NUM> (<NUM>) registers in PLMN <NUM> (<NUM>) by way of example, the PLMN, in which the electronic device is able to register, is not necessarily fixed, and the registered PLMN may be changed in various embodiments.

In various embodiments, one or more PLMN IDs may be stored in the electronic devices <NUM> and <NUM>. For example, information stored in the electronic devices <NUM> and <NUM> when users of the electronic devices <NUM> and <NUM> subscribe to the cellular communication service, such as information on the PLMN to which the user subscribed (home PLMM, HPLMN) and information on the PLMN in which the corresponding electronic devices <NUM> and <NUM> most recently registered (registered PLMN, RPLMN), may be stored in a user subscriber identity module (USIM). For example, assuming that electronic device <NUM> (<NUM>) subscribed to PLMN <NUM> (<NUM>), PLMN <NUM> (<NUM>) may be stored in electronic device <NUM> (<NUM>) as an HPLMN. For example, if electronic device <NUM> (<NUM>) registers in PLMN <NUM> (<NUM>), PLMN <NUM> (<NUM>) may be stored in electronic device <NUM> as an RPLMN.

In various embodiments, the electronic devices <NUM> and <NUM> may preferentially search for an RPLMN or HPLMN when searching for a PLMN. The electronic devices <NUM> and <NUM> may search for available PLMNs, and if there is a PLMN that matches a stored RPLMN or HPLMN, the electronic devices <NUM> and <NUM> may select the matching PLMN, and may then stop searching for the PLMN. Thereafter, the electronic device may perform selection of a cell among the cells of the selected PLMN and location registration therein.

In various embodiments, the electronic devices <NUM> and <NUM> may communicate with one of the base stations <NUM> to <NUM> that belong to the PLMNs <NUM> and <NUM>. The electronic devices <NUM> and <NUM> may operate so as to transmit and receive information, signals, data, or messages to and from one of the base stations <NUM> to <NUM>. For example, the electronic devices <NUM> and <NUM> may receive system information messages that are periodically broadcast by the base stations <NUM> to <NUM>.

In various embodiments, the electronic devices <NUM> and <NUM> may operate based on a specific RAT. For example, the electronic devices <NUM> and <NUM> may use cellular communication services, based on at least one or more RATs among the RATs such as <NUM> (e.g., GSM), <NUM> (e.g., WCDMA), <NUM> (e.g., LTE), <NUM>, or the like. In various embodiments, one electronic device may support a plurality of RATs. For example, electronic device <NUM> (<NUM>) that has registered in PLMN <NUM> (<NUM>) in <FIG> may be an electronic device that supports all of <NUM>, <NUM>, and <NUM> RATs. In this case, although electronic device <NUM> (<NUM>) is able to use all communication services in <NUM>, <NUM>, and <NUM> standards provided by PLMN <NUM> (<NUM>), in general, electronic device <NUM> (<NUM>) may select one of them according to priority, and may access the same.

<FIG> is a block diagram of an electronic device for searching for a PLMN according to various embodiments. The electronic device shown in <FIG> may be the electronic device <NUM> shown in <FIG> and the electronic device <NUM> or <NUM> shown in <FIG>.

Referring to <FIG>, the electronic device <NUM> may include a processor <NUM>, a memory <NUM>, a communication circuit <NUM>, and an antenna <NUM>. In various embodiments, the processor <NUM> may include the processor <NUM> shown in <FIG>, the memory <NUM> may include the memory <NUM> shown in <FIG>, the communication circuit <NUM> may include the communication module <NUM> or the wireless communication module <NUM> shown in <FIG>, and the antenna <NUM> may include the antenna <NUM> shown in <FIG>.

In various embodiments, the electronic device <NUM> may be a device receiving a cellular communication service. For example, the electronic device <NUM> may be a mobile phone, a smartphone, a music player, a portable game console, a navigation system, a laptop computer, or the like, which is provided with a cellular communication service. Depending on communication standards or RATs, the electronic device <NUM> may be referred to as "user equipment (UE)", a "terminal", a "mobile station", a "station (STA)", or the like.

In various embodiments, the electronic device <NUM> may support a specific RAT for a cellular communication service. For example, the electronic device <NUM> may use a cellular communication service, based on at least one or more of the RATs such as <NUM> (e.g., GSM), <NUM> (e.g., WCDMA), <NUM> (e.g., LTE), <NUM>, or the like. In various embodiments, the electronic device <NUM> may support a plurality of RATs. For example, the electronic device may be an electronic device supporting all of <NUM>, <NUM>, and <NUM> RATs.

In various embodiments, the processor <NUM> may generate, obtain, process, or configure information, data, a message, or a signal to be transmitted using cellular communication. In various embodiments, the processor <NUM> may transmit, using cellular communication, the generated, obtained, processed, or configured information, data, message, or signal to another electronic device (e.g., the base station <NUM>) by controlling the communication circuit <NUM>. In various embodiments, the information, data, message, or signal transmitted to another electronic device (e.g., the base station <NUM>) may include at least one piece of control information or user data.

In various embodiments, the processor <NUM> may receive, using cellular communication, information, data, a message, or a signal from another electronic device (e.g., the base station <NUM>) by controlling the communication circuit <NUM>. In various embodiments, the processor <NUM> may process the information, data, message, or signal received from another electronic device (e.g., the base station <NUM>). In various embodiments, the information, data, message, or signal received from another electronic device (e.g., the base station <NUM>) may include at least one piece of control information or user data.

In various embodiments, the processor <NUM> may perform the above-described operations, based on execution of at least one of instructions, code, software, or commands stored in the memory <NUM>.

In various embodiments, the memory <NUM> may store control command code and control data (e.g., instructions, software, commands, etc.) for controlling the electronic device <NUM>, or user data. For example, the memory <NUM> may store at least one of an application, an operating system (OS), middleware, or a device driver.

In various embodiments, the memory <NUM> may be operatively or operably coupled to the processor <NUM>.

In various embodiments, the communication circuit <NUM> may perform functions for transmitting or receiving information, signals, data, or messages through a wireless channel using cellular communication. In various embodiments, the communication circuit <NUM> may perform a function of conversion between a baseband signal and a bitstream according to a physical-layer standard of the system. For example, when transmitting data, the communication circuit <NUM> may encode and modulate transmission bitstreams, thereby generating complex symbols. As another example, when receiving data, the communication circuit <NUM> may demodulate and decode a baseband signal, thereby restoring a reception bitstream.

The communication circuit <NUM> may up-convert the baseband signal into an RF band signal, and may transmit the same through the antenna <NUM>. In various embodiments, the antenna <NUM> may be configured to be appropriate to a multiple-input-multiple-output (MIMO) scheme or a beam-based communication scheme. The communication circuit <NUM> may down-convert the RF band signal received through the antenna <NUM> into a baseband signal. For example, the communication circuit <NUM> may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital analog converter (DAC), an analog digital converter (ADC), and the like.

In various embodiments, the communication circuit <NUM> and the antenna <NUM> may support a plurality of RATs. The antenna <NUM> supporting a plurality of RATs may perform transmission and reception for respective RF bands of all the RATs, and the communication circuit <NUM> may convert the RF band signals of all the RATs into baseband signals, and vice versa.

In various embodiments, the communication circuit <NUM> may be operatively coupled to the processor <NUM>.

In various embodiments, the processor <NUM> may receive at least one system information message. In various embodiments, the processor <NUM> may receive the system information message through the communication circuit <NUM>. In various embodiments, the system information message may include information in order for the electronic device <NUM> to access a specific cell controlled by a base station (e.g., the base station <NUM>) and to operate properly. For example, the system information message may include a PLMN ID, a cell ID, RAT information, frequency information, and information related to cell reselection.

In various embodiments, in the case where the electronic device <NUM> performs cellular communication using an LTE or WCDMA RAT, the system information message may be used to transmit system information blocks (SIBs). The SIBs may be periodically broadcast by the base station <NUM> to then be transmitted to the electronic device <NUM>.

In various embodiments, the system information message may include information related to scheduling of other SIBs. For example, a list of SIBs to be transmitted and transmission periods thereof may be included in the system information message. For example, information related to scheduling of other SIBs may be included in the system information message such as SIB1.

In various embodiments, the system information message may include information related to inter-frequency or inter-RAT cell reselection. For example, the system information message may include a list of neighbor cells necessary for cell reselection.

In various embodiments, in the case of a system information message in the LTE standard, information related to cell reselection may be included in the system information message such as SIB5, SIB6, or SIB7. For example, inter-frequency neighbor-cell information may be included in SIB5. For example, WCDMA neighbor-cell information may be included in SIB6. For example, GSM neighbor-cell information may be included in SIB7. In various embodiments, in the case of a system information message in the WCDMA standard, information related to cell reselection may be included in the system information message such as SIB11, SIB12, or SIB19.

In various embodiments, the processor <NUM> may identify at least one RAT, based on the received system information message, from among a plurality of RATs supported by the electronic device <NUM>. In various embodiments, the processor <NUM> may determine, based on the system information message, the RAT that is supported by the network (e.g., PLMNs <NUM> and <NUM>) that transmitted the system message and/or the RAT that is not supported by the same.

In various embodiments, the processor <NUM> may identify at least one RAT, based on the information related to inter-frequency or inter-RAT cell reselection, which is included in the system information message. In various embodiments, the processor <NUM> may identify the at least one RAT from information on the neighbor cell necessary for cell reselection, which is included in the system information message. For example, the processor <NUM> may identify the at least one RAT by determining the RAT served by the neighbor cell included in the system information message.

For example, if the processor <NUM> receives a system information message in the LTE standard, the processor <NUM> may identify the at least one RAT, based on the system information message such as SIB5, SIB6, or SIB7 including information related to cell reselection. For example, if the processor <NUM> receives SIB5, and if SIB5 includes neighbor-cell information, the processor <NUM> may determine that the network that transmitted SIB5 supports LTE. For example, if the processor <NUM> receives SIB6, and if SIB6 includes neighbor-cell information, the processor may determine that the network that transmitted SIB6 supports WCDMA. For example, if the processor <NUM> receives SIB7, and if SIB7 includes neighbor-cell information, the processor <NUM> may determine that the network that transmitted SIB7 supports a GSM RAT.

For example, if the processor <NUM> receives a system information message in the WCDMA standard, the processor <NUM> may identify the at least one RAT using the system information message such as SIB11, SIB12, or SIB19 including information related to cell reselection. For example, if the processor <NUM> receives a system information message in the GSM standard, the processor <NUM> may identify the at least one RAT, based on the system information message such as an SI2 quarter including information related to cell reselection.

In various embodiments, the processor <NUM> may identify the at least one RAT, based on information related to scheduling of system information blocks (SIBs) included in the system information message. For example, if the processor <NUM> receives a system information message in the LTE or WCDMA standard, the processor <NUM> may identify the at least one RAT from the information related to scheduling of SIBs included in the received SIB1. For example, if SIB5, SIB6, or SIB7 is included in the list of SIBs to be transmitted, which is included in SIB1, the processor <NUM> may determine LTE, WCDMA, or GSM to be the RAT supported by the network that transmitted SIB1 in each case. Alternatively, if SIB6 or SIB7 is not included in the list of SIBs to be transmitted, the processor <NUM> may determine WCDMA or GSM to be the RAT that is not supported by the network that transmitted SIB1 in each case.

In various embodiments, the processor <NUM> may search for a PLMN on at least one identified RAT. In various embodiments, the processor <NUM> may search for an available PLMN using only the RF band of at least one identified RAT. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one RAT includes only <NUM>, the processor <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>.

In various embodiments, if the processor <NUM> fails to find the PLMN on the at least one RAT, the processor <NUM> may search for a PLMN on all RATs supported by the electronic device <NUM>. In various embodiments, the processor <NUM> may search for an available PLMN using all RF bands supported by the electronic device <NUM>. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one RAT includes only <NUM>, and if no available PLMN is found as a result of searching for the PLMN using only the RF band of <NUM>, the processor <NUM> may search for an available PLMN using all RF bands of <NUM>, <NUM>, and <NUM>.

In various embodiments, if the processor <NUM> fails to find a PLMN on the at least one RAT, the processor <NUM> may search for a PLMN on the RATs other than the at least one RAT, among a plurality of RATs supported by the electronic device <NUM>. In various embodiments, the processor <NUM> may search for an available PLMN using a band that is not included in the RF band of the at least one RAT, among all RF bands supported by the electronic device <NUM>. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one RAT includes only <NUM>, and if no available PLMN is found as a result of searching for the PLMN using only the RF band of <NUM>, the processor <NUM> may search for an available PLMN using the RF bands of <NUM> and <NUM>.

In various embodiments, the searching for a PLMN on the at least one RAT may be searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN, RPLMN). In various embodiments, if the searching for the PLMN fails as a result of searching for the RPLMN on the at least one RAT, the processor <NUM> may search for a PLMN other than the RPLMN (e.g., an HPLMN or the like). In this case, the processor <NUM> may perform searching on all the RATs supported by the electronic device <NUM>, instead of performing searching on the at least one RAT.

In various embodiments, the electronic device <NUM> may repeat the searching for a PLMN for a predetermined time or until an available PLMN is found.

In various embodiments, the at least one RAT may be at least one of <NUM>, <NUM>, <NUM>, and <NUM>.

In various embodiments, the processor <NUM> may store the at least one RAT in order to use the same for searching for a PLMN. For example, the processor <NUM> may store the at least one RAT in response to selection of a PLMN. For example, the processor <NUM> may store the at least one RAT in response to completion of location registration therein. In various embodiments, the processor <NUM> may update an existing stored RAT with the at least one RAT.

In various embodiments, the processor <NUM> may store the at least one RAT in the memory <NUM>. In various embodiments, the at least one stored RAT may be maintained without being deleted even while power is not supplied to the electronic device <NUM>.

In various embodiments, the processor <NUM> may search for a PLMN on the at least one stored RAT. In various embodiments, the processor <NUM> may search for an available PLMN using only the RF band of the at least one stored RAT. For example, although the electronic device <NUM> supports all of the <NUM>, <NUM>, and <NUM> RATs, if only <NUM> is included in the stored RAT, the processor <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>. In various embodiments, if there is at least one stored RAT, the processor <NUM> may omit the operations of receiving a system information message for searching for the PLMN and identifying at least one RAT, based on the system information message.

In various embodiments, the processor <NUM> may identify that the electronic device, which was turned off after storing the at least one RAT, switches to a turn-on state. In response to the identification, the processor <NUM> may search for a PLMN on the at least one stored RAT. In various embodiments, the processor <NUM> may identify interruption of a communication service of the electronic device after storing the at least one RAT. In response to the identification, the processor <NUM> may search for a PLMN on the at least one stored RAT.

In various embodiments, if the processor <NUM> fails to find the PLMN on the at least one stored RAT, the processor <NUM> may search for a PLMN for all the RATs supported by the electronic device <NUM>. In various embodiments, in response to identifying that the searching for a PLMN fails on the at least one stored RAT, the processor <NUM> may search for a PLMN on the RAT other than the at least one stored RAT, among the plurality of RATs.

In various embodiments, the processor <NUM> may identify whether or not RAT information supported by the PLMN is stored in the memory <NUM>. In various embodiments, if there is RAT information stored in the memory <NUM>, the processor <NUM> may search for a PLMN on at least one RAT included in the stored RAT information. For example, the processor <NUM> may search for an available PLMN using only the RF band of the at least one RAT included in the stored RAT information. In various embodiments, if there is no RAT information stored in the memory <NUM>, the processor <NUM> may search for a PLMN on all the RATs supported by the electronic device <NUM>.

In various embodiments, if an available PLMN is found as a result of searching for the PLMN, the processor <NUM> may register in the found PLMN in response thereto. The processor <NUM> may perform selection of a cell from among the cells of the found PLMN and location registration therein.

In various embodiments, the processor <NUM> may identify RAT information supported by the registered PLMN in response to registration of the electronic device <NUM> in the available PLMN. For example, the processor <NUM> may receive at least one system information message provided by the registered PLMN, and may identify at least one RAT supported by the registered PLMN, based on the at least one system message.

In various embodiments, the processor <NUM> may store the RAT information supported by the registered PLMN in the memory <NUM>, based on the identification. For example, the processor <NUM> may update existing stored RAT information with the RAT supported by the registered PLMN.

As described above, the electronic device <NUM> supporting a plurality of RATs according to various embodiments may identify at least one RAT, based on the system information message, instead of searching for a PLMN on all supported RATs, and may search for a PLMN on only the at least one RAT, thereby reducing the time required for the searching for a PLMN. The electronic device <NUM> according to various embodiments may identify at least one RAT, based on the system information message, and may search for a PLMN only on the at least one RAT, thereby reducing current consumption during the searching for a PLMN. According to an embodiment, if the disclosure is applied to searching for an RPLMN, the time required for searching may be reduced as shown in Table <NUM> below. However, the disclosure is not limited thereto.

As described above, an electronic device (e.g., the electronic device <NUM>) according to various embodiments may include: a housing; a wireless communication circuit positioned in the housing; a processor operatively connected to the wireless communication circuit; and a memory positioned in the housing and operatively connected to the processor, wherein the memory may store instructions that cause, when executed, the processor to perform camp-on on a cell of a first base station through the wireless communication circuit, receive, from the first base station, information related to a network related to the first base station, identify a state in which no service is provided from the first base station to the electronic device, and search for a registered public land mobile network (RPLMN), based at least in part on the received information.

In various embodiments, the information related to the network may include at least one system information block (SIB), and the at least one SIB may include radio access technology (RAT) information, which is supported by the network. In various embodiments, the instructions may cause the processor to search for the RPLMN using the RAT information supported by the network. In various embodiments, the instructions may cause the processor to store the RAT information in the memory and, if the network information is changed, to update the RAT information.

In various embodiments, the instructions may cause the processor, if the RPLMN is not found by searching for the RPLMN, to search for an HPLMN using RAT information supported by the electronic device. In various embodiments, the instructions may cause the processor, if the HPLMN is not found by searching for the HPLMN, to search for a PLMN available for the electronic device.

An electronic device according to various embodiments described above may include: a housing; a wireless communication circuit positioned in the housing; a processor operatively connected to the wireless communication circuit; and a memory positioned in the housing and operatively connected to the processor, wherein the memory may store instructions that cause, when executed, the processor to perform camp-on on a cell of a first base station through the wireless communication circuit, store information related to a network, which is received from the first base station, and, if the electronic device is rebooted after storing the information, search for a registered public land mobile network (RPLMN), based at least in part on the stored information.

In various embodiments, the information related to the network may be received from the first base station through at least one system information message. In various embodiments, the at least one system information message may be used to provide information related to inter-frequency or inter-RAT cell reselection.

In various embodiments, the searching for the RPLMN may be performed in response to identifying that the rebooting is completed.

As described above, an electronic device (e.g., the electronic device <NUM>) supporting a plurality of radio access technologies (RATs) according to various embodiments may include: at least one memory (e.g., the memory <NUM>); a communication circuit (e.g., the communication circuit <NUM>); and at least one processor (e.g., the processor <NUM>) operatively coupled to the at least one memory and the communication circuit, wherein the at least one processor may be configured to receive at least one system information message through the communication circuit, identify at least one RAT among the plurality of RATs, based on the at least one system information message, and search for a public land mobile network (PLMN) on the at least one RAT.

In various embodiments, the at least one processor may be further configured to store at least one identified RAT in the memory in order to use the same in searching for a PLMN.

In various embodiments, the at least one system information message may be information related to inter-frequency or inter-RAT cell reselection. In various embodiments, the at least one system information message may be information related to scheduling of system information blocks (SIBs).

In various embodiments, the at least one processor may be further configured to search for a PLMN on a RAT other than the at least one RAT among the plurality of RATs in response to identifying that the searching for a PLMN on the at least one RAT fails.

In various embodiments, the at least one processor may be further configured to: in response to selection of an available PLMN as a result of searching for a PLMN on the at least one RAT, register in the selected PLMN; in response to the registration, identify at least one RAT, based on a system information message of the registered PLMN; and store the at least one identified RAT in the memory.

In various embodiments, the searching for a PLMN on the at least one RAT is searching for the PLMN in which the electronic device most recently registered (registered PLMN).

In various embodiments, the RAT may be at least one of <NUM>, <NUM>, <NUM>, and <NUM>.

<FIG> illustrates an example of an operation in which an electronic device searches for a PLMN according to various embodiments. This operation may be performed by the electronic device <NUM> shown in <FIG>, the electronic device <NUM> or the electronic device <NUM> shown in <FIG>, the electronic device <NUM> shown in <FIG>, or the processor <NUM> of the electronic device <NUM>.

Referring to <FIG>, in operation <NUM>, the electronic device <NUM> may receive at least one system information message. In various embodiments, the system information message may include information in order for the electronic device to access a specific cell controlled by the base station and to operate appropriately. For example, the system information message may include a PLMN ID, a cell ID, RAT information, frequency information, and information related to cell reselection.

In various embodiments, in the case where the electronic device <NUM> performs cellular communication using an LTE or WCDMA RAT, the system information message may be used to transmit system information blocks (SIBs). The SIBs may be periodically broadcast by the base station to then be transmitted to the electronic device <NUM>.

In operation <NUM>, the electronic device <NUM> may identify at least one RAT, based on the received system information message, among a plurality of supportable RATs. The electronic device <NUM> may determine the RAT supported by the network that transmitted the system message and/or the RAT that is not supported by the same, based on the system information message.

In various embodiments, the electronic device <NUM> may identify at least one RAT, based on information related to the inter-frequency or inter-RAT cell reselection, which is included in the system information message. In various embodiments, the electronic device <NUM> may identify the at least one RAT from information on a neighbor cell necessary for cell reselection, which is included in the system information message. For example, the electronic device <NUM> may identify the at least one RAT by determining the RAT served by the neighbor cell included in the system information message.

For example, if the electronic device <NUM> receives a system information message in the LTE standard, the electronic device <NUM> may identify the at least one RAT, based on the system information message such as SIB5, SIB6, or SIB7 including information related to cell reselection. For example, if the electronic device <NUM> receives SIB5, and if SIB5 includes neighbor-cell information, the electronic device <NUM> may determine that the network that transmitted SIB5 supports LTE. For example, if the electronic device <NUM> receives SIB6, and if SIB6 includes neighbor-cell information, the electronic device <NUM> may determine that the network that transmitted SIB6 supports WCDMA. For example, if the electronic device <NUM> receives SIB7, and if SIB7 includes neighbor-cell information, the electronic device <NUM> may determine that the network that transmitted SIB7 supports a GSM RAT.

For example, if the electronic device <NUM> receives a system information message in the WCDMA standard, the electronic device <NUM> may identify the at least one RAT using the system information message such as SIB11, SIB12, or SIB19 including information related to cell reselection. For example, if the electronic device <NUM> receives a system information message in the GSM standard, the electronic device <NUM> may identify the at least one RAT, based on the system information message such as an SI2 quarter including information related to cell reselection.

In various embodiments, the electronic device <NUM> may identify the at least one RAT, based on information related to scheduling of system information blocks (SIBs) included in the system information message. For example, if the electronic device <NUM> receives a system information message in the LTE or WCDMA standard, the electronic device <NUM> may identify the at least one RAT from a list of SIBs to be transmitted, which is included in the received SIB1. For example, if SIB5, SIB6, or SIB7 is included in the list of SIBs to be transmitted, which is included in SIB1, the electronic device <NUM> may determine LTE, WCDMA, or GSM to be the RAT supported by the network that transmitted SIB1 in each case. Alternatively, if SIB6 or SIB7 is not included in the list of SIBs to be transmitted, the electronic device <NUM> may determine WCDMA or GSM to be the RAT that is not supported by the network that transmitted SIB1 in each case.

In operation <NUM>, the electronic device <NUM> may search for a PLMN on the at least one identified RAT. In various embodiments, the electronic device <NUM> may search for an available PLMN using only the RF band of the at least one identified RAT. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one identified RAT includes only <NUM>, the electronic device <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>.

In various embodiments, the searching for a PLMN on the at least one RAT may be searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN).

<FIG> illustrates an example of an operation <NUM> in which an electronic device searches for a registered public land mobile network (RPLMN) according to various embodiments.

Referring to <FIG>, in operation <NUM>, the electronic device <NUM> may perform camp-on on the cell of a first base station (e.g., the electronic device <NUM>). In various embodiments, the electronic device <NUM> may perform camp-on on the cell of the first base station located in proximity to the electronic device <NUM> in order to receive a cellular communication service.

In operation <NUM>, after performing camp-on on the cell of the first base station, the electronic device <NUM> may receive information related to the network related to the first base station. In various embodiments, the information may be received through at least one system information message broadcast from the first base station. In various embodiments, the at least one system information message may include information on resources required to access or use the network. However, the disclosure is not limited thereto. In various embodiments, information related to the network related to the first base station may include RAT information supported by the network.

In various embodiments, the electronic device <NUM> may store information, related to the network related to the first base station, in a memory (e.g., the memory <NUM>). For example, the electronic device <NUM> may store the RAT information in the memory. In various embodiments, if another piece of RAT information is stored in the memory before receiving the RAT information in operation <NUM>, the electronic device <NUM> may change the another piece of RAT information stored in the memory into the RAT information. For example, if another piece of RAT information is stored in the memory before receiving the RAT information in operation <NUM>, the electronic device <NUM> may update or refine the another piece of RAT information with the RAT information. The electronic device <NUM> according to various embodiments may maintain the context of the electronic device <NUM> related to communication in the latest state through the update.

In operation <NUM>, the electronic device <NUM> may identify that the electronic device <NUM> is in the state in which no service is provided from the first base station. For example, if the electronic device <NUM> is located in the shaded area, the electronic device <NUM> may identify that the electronic device <NUM> is in the state in which no service is provided from the first base station. In various embodiments, the electronic device <NUM> may identify that the electronic device <NUM> is in the state in which no service is provided from the first base station, based on identifying that the signal received from the first base station is not received within a specified time or that the received signal strength indicator (RSSI) of the signal received from the first base station is lower than a threshold. However, the disclosure is not limited thereto.

In operation <NUM>, in response to the identification, the electronic device <NUM> may search for a registered public land mobile network (RPLMN), based on the received information. In various embodiments, since the electronic device <NUM> identifies that the electronic device is in the state in which no service is provided from the first base station, the electronic device <NUM> may search for the RPLMN in order to receive the cellular communication service. In various embodiments, the electronic device <NUM> may perform the RPLMN, based on the information (e.g., the RAT information), instead of performing the RPLMN on all the RATs available for the electronic device <NUM>. Searching for the RPLMN based on the information may reduce the amount of load of the electronic device <NUM>, which is required to perform the RPLMN.

In various embodiments, if the electronic device <NUM> identifies that the RPLMN is not found by the searching for the RPLMN, the electronic device <NUM> may search for an HPLMN using information on the RATs supported by the electronic device <NUM>. In various embodiments, if the electronic device <NUM> identifies that the HPLMN is not found by the searching for the HPLMN, the electronic device <NUM> may search for a PLMN available for the electronic device <NUM>. However, the disclosure is not limited thereto.

As described above, the electronic device <NUM> according to various embodiments, after searching for the RPLMN, based on information received from the first base station on which the electronic device <NUM> has most recently camped, may sequentially search for the HPLMN and the PLMN. For example, the electronic device <NUM> may search for the PLMN (for example, search for the RPLMN) from the narrow range, based on the context of the electronic device <NUM>, thereby improving resource efficiency.

<FIG> illustrates another example of an operation in which an electronic device searches for an RPLMN according to various embodiments.

Referring to <FIG>, in operation <NUM>, the electronic device <NUM> may perform camp-on on the cell of the first base station.

In operation <NUM>, the electronic device <NUM> may store information related to the network, which is received from the first base station. In various embodiments, the information related to the network may be received through the system information message. In various embodiments, the information related to the network may include data for indicating the RAT related to the network. In various embodiments, if the electronic device <NUM> newly accesses the network thereafter, the electronic device <NUM> may store information received from the first base station in order to use the data for indicating the RAT.

In operation <NUM>, if the electronic device <NUM> is rebooted after the information is stored, the electronic device <NUM> may search for an RPLMN, based on at least some of the stored information. For example, if a user restarts the electronic device <NUM> that is connected to the first base station, or if a user turns on the electronic device <NUM> after turning off the electronic device <NUM> in the state of being connected to the first base station, the electronic device <NUM> may perform the rebooting. Due to the rebooting, the electronic device <NUM> may be required to search for a PLMN in order to receive a cellular communication service. The electronic device <NUM> according to various embodiments may search for an RPLMN, based at least on the information, instead of performing full searching for the PLMN. By searching for the RPLMN as described above, the electronic device <NUM> may reduce the amount of resource consumption necessary for searching for the PLMN. In addition, the electronic device <NUM> according to various embodiments may reduce the time for searching for the PLMN by performing searching for the RPLMN.

<FIG> illustrates an example of an operation in which an electronic device identifies a RAT and then searches for a PLMN on the identified RAT according to various embodiments. This operation may be performed by the electronic device <NUM> shown in <FIG>, the electronic device <NUM> or the electronic device <NUM> shown in <FIG>, the electronic device <NUM> shown in <FIG>, or the processor <NUM> of the electronic device <NUM>.

<FIG> may be a detailed flowchart of operation <NUM> described with reference to <FIG>. Operations <NUM> to <NUM> in <FIG> may be performed after the electronic device <NUM> performs operation <NUM> in <FIG>.

In operation <NUM>, the electronic device <NUM> may store at least one identified RAT to be used for searching for a PLMN. In various embodiments, the electronic device <NUM> may update a previously stored RAT with at least one identified RAT.

In various embodiments, the electronic device <NUM> may store the at least one RAT in the memory <NUM>. In various embodiments, the at least one stored RAT may be maintained without being deleted even while the power is not supplied to the electronic device <NUM>.

In operation <NUM>, the electronic device <NUM> may search for a PLMN on at least one identified RAT. In various embodiments, the electronic device <NUM> may search for an available PLMN using only the RF band of at least one identified RAT. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the stored RAT includes only <NUM>, the electronic device <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>.

In various embodiments, the searching for a PLMN on at least one identified RAT may be searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN).

In operation <NUM>, the electronic device <NUM> may identify whether or not an available PLMN is found as a result of searching for a PLMN. For example, the electronic device <NUM> may identify whether or not an available PLMN is found as a result of searching for a PLMN on at least one identified RAT. If an available PLMN is not found as a result of searching for a PLMN, the electronic device <NUM> may perform operation <NUM>. On the other hand, if an available PLMN is found as a result of searching for a PLMN, the electronic device <NUM> may perform operation <NUM>.

In operation <NUM>, if the electronic device <NUM> fails to find a PLMN on at least one identified RAT, the electronic device <NUM> may search for a PLMN on the RAT other than the at least one identified RAT among a plurality of RATs supported by the electronic device <NUM>. The electronic device <NUM> may search for an available PLMN using a band that is not included in the RF band of the at least one identified RAT, among all the RF bands supported by the electronic device <NUM>. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if at least one identified RAT includes only <NUM>, and if no available PLMN is found as a result of searching for a PLMN using only the RF band of <NUM>, the electronic device <NUM> may search for an available PLMN using the RF bands of <NUM> and <NUM>.

In various embodiments, if the searching for a PLMN on at least one identified RAT is searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN, RPLMN), and if the searching for the PLMN fails as a result of searching for the RPLMN on at least one identified RAT, the electronic device <NUM> may search for a PLMN other than the RPLMN (e.g., an HPLMN or the like). In this case, the electronic device <NUM> may search for all the RATs supported by the electronic device <NUM>, instead of performing searching on at least one identified RAT.

After performing operation <NUM>, the electronic device <NUM> may return to operation <NUM>, and may identify whether or not an available PLMN is found as a result of searching for a PLMN on the RAT other than the at least one identified RAT. In various embodiments, the electronic device <NUM> may repeat operations <NUM> and <NUM> for a predetermined time or until an available PLMN is found.

In operation <NUM>, if an available PLMN is found as a result of searching for the PLMN, the electronic device <NUM> may register in the found PLMN in response thereto. The electronic device <NUM> may perform selection of a cell from among the cells of the found PLMN and location registration therein.

Although <FIG> shows an example in which the electronic device <NUM> performs operations <NUM> to <NUM> after performing operation <NUM>, operation <NUM> may be performed regardless of operations <NUM> to <NUM> in sequence thereof. For example, operation <NUM> may be performed simultaneously with operations <NUM> to <NUM>, and may be performed after operation <NUM>, <NUM>, <NUM>, or <NUM> is performed.

<FIG> illustrates an example of an operation <NUM> in which an electronic device searches for a PLMN according to various embodiments. This operation may be performed by the electronic device <NUM> shown in <FIG>, the electronic device <NUM> or the electronic device <NUM> shown in <FIG>, the electronic device <NUM> shown in <FIG>, or the processor <NUM> of the electronic device <NUM>.

Operations <NUM> to <NUM> in <FIG> may correspond to operations <NUM> to <NUM> in <FIG>. Operation <NUM> in <FIG> may correspond to operation <NUM> in <FIG>. Operations <NUM> to <NUM> in <FIG> may correspond to operations <NUM> to <NUM> in <FIG>.

Referring to <FIG>, in operation <NUM>, the electronic device <NUM> receives at least one system information message. In various embodiments, the system information message may include information in order for the electronic device <NUM> to access a specific cell controlled by a base station and to operate properly. For example, the system information message may include a PLMN ID, a cell ID, RAT information, frequency information, and information related to cell reselection.

In various embodiments, in the case of a system information message in the LTE standard, the information related to cell reselection may be included in the system information message such as SIB5, SIB6, or SIB7. For example, inter-frequency neighbor-cell information may be included in SIB5. For example, WCDMA neighbor-cell information may be included in SIB6. For example, GSM neighbor-cell information may be included in SIB7. In various embodiments, in the case of a system information message in the WCDMA standard, information related to cell reselection may be included in the system information message such as SIB11, SIB12, or SIB19.

In operation <NUM>, the electronic device <NUM> identifies at least one RAT, based on the received system information message, from among a plurality of supportable RATs. The electronic device <NUM> may determine the RAT supported by the network that transmitted the system information message and/or the RAT that is not supported by the same, based on the system information message.

In various embodiments, the electronic device <NUM> may identify the at least one RAT, based on information related to the inter-frequency or inter-RAT cell reselection, which is included in the system information message. In various embodiments, the electronic device <NUM> may identify the at least one RAT from information on the neighbor cell necessary for cell reselection, which is included in the system information message. For example, the electronic device <NUM> may identify the at least one RAT by determining the RAT served by a neighbor cell included in the system information message.

For example, if the electronic device <NUM> receives a system information message in the LTE standard, the electronic device <NUM> may identify the at least one RAT, based on the system information message such as SIB5, SIB6, or SIB7 including information related to cell reselection. For example, if the electronic device <NUM> receives SIB5, and if SIB5 includes neighbor-cell information, the electronic device <NUM> may determine that the network that transmitted SIB5 supports LTE. For example, if the electronic device <NUM> receives SIB6, and if SIB6 includes neighbor-cell information, the processor may determine that the network that transmitted SIB6 supports WCDMA. For example, if the electronic device <NUM> receives SIB7, and if SIB7 includes neighbor-cell information, the electronic device <NUM> may determine that the network that transmitted SIB7 supports a GSM RAT.

In various embodiments, the electronic device <NUM> may identify the at least one RAT, based on information related to scheduling of system information blocks (SIBs), which is included in the system information message. For example, if the electronic device <NUM> receives a system information message in the LTE or WCDMA standard, the electronic device <NUM> may identify the at least one RAT from a list of SIBs to be transmitted, which is included in the received SIB1. For example, if SIB5, SIB6, or SIB7 is included in the list of SIBs to be transmitted, which is included in SIB1, the electronic device <NUM> may determine LTE, WCDMA, or GSM to be the RAT supported by the network that transmitted SIB1 in each case. Alternatively, if SIB6 or SIB7 is not included in the list of SIBs to be transmitted, the electronic device <NUM> may determine WCDMA or GSM to be the RAT that is not supported by the network that transmitted SIB1 in each case.

In operation <NUM>, the electronic device <NUM> may search for a PLMN on the at least one identified RAT. In various embodiments, the electronic device <NUM> may search for an available PLMN using only the RF band of the at least one identified RAT.

Operation <NUM> may correspond to operation <NUM> in <FIG> or operations <NUM> to <NUM> in <FIG>. In various embodiments, if the electronic device <NUM> fails to find a PLMN on the at least one identified RAT, the electronic device <NUM> may search for a PLMN on the RATs other than the at least one identified RAT among a plurality of RATs supported by the electronic device <NUM>. The electronic device <NUM> may search for an available PLMN using a band that is not included in the RF band of the at least one identified RAT, among all RF bands supported by the electronic device. In various embodiments, the electronic device <NUM> may repeat searching for a PLMN for a predetermined time or until an available PLMN is found.

In operation <NUM>, if an available PLMN is found as a result of searching for the PLMN, the electronic device <NUM> registers in the found PLMN in response thereto. The electronic device <NUM> performs selection of a cell from among the cells of the found PLMN and location registration therein.

In operation <NUM>, the electronic device <NUM> stores at least one identified RAT to be used for searching for a PLMN. For example, the electronic device <NUM> may store the at least one RAT in response to selection of a PLMN. The electronic device <NUM> stores the at least one RAT in response to location registration therein. In various embodiments, the electronic device <NUM> may update a previously stored RAT with the at least one RAT.

In various embodiments, the electronic device <NUM> may store the at least one RAT in the memory <NUM>. In various embodiments, the at least one stored RAT may be maintained without being deleted even while power is not supplied to the electronic device <NUM>.

In operation <NUM>, the electronic device <NUM> identifies interruption of a communication service, which is provided to the electronic device <NUM> by the registered PLMN, after storing the at least one RAT. For example, the electronic device <NUM> may identify that the electronic device <NUM> in a turn-off state switches to a turn-on state. For example, the electronic device <NUM> may identify the lack of coverage.

In operation <NUM>, in response to identifying the interruption of the communication service, the electronic device <NUM> searches for a PLMN on at least one stored RAT. In various embodiments, the electronic device <NUM> may search for an available PLMN using only the RF band of the at least one stored RAT. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one stored RAT includes only <NUM>, the electronic device <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>.

In various embodiments, the searching for a PLMN on the at least one stored RAT may be searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN).

In operation <NUM>, the electronic device <NUM> may identify whether or not an available PLMN is found as a result of searching for the PLMN on the at least one stored RAT. If no available PLMN is found as a result of searching for the PLMN, the electronic device <NUM> performs operation <NUM>. On the other hand, if an available PLMN is found as a result of searching for the PLMN, the electronic device <NUM> may perform operation <NUM>.

In operation <NUM>, if the electronic device <NUM> fails to find a PLMN on the at least one stored RAT, the electronic device <NUM> searches for a PLMN on the RATs other than the at least one stored RAT among a plurality of RATs supported by the electronic device <NUM>. The electronic device <NUM> may search for an available PLMN using a band that is not included in the RF band of the at least one stored RAT, among all RF bands supported by the electronic device <NUM>. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one stored RAT includes only <NUM>, and if no available PLMN is found as a result of searching for the PLMN using only the RF band of <NUM>, the electronic device <NUM> may search for an available PLMN using the RF bands of <NUM> and <NUM>.

In various embodiments, if the searching for a PLMN on the at least one identified RAT is searching for the PLMN in which the electronic device <NUM> most recently registered (registered PLMN), and if the searching for the PLMN fails as a result of searching for the RPLMN on the at least one stored RAT, the electronic device <NUM> may search for a PLMN other than the RPLMN (e.g., an HPLMN or the like). In this case, the electronic device <NUM> may search for all the RATs supported by the electronic device <NUM>, instead of searching for the at least one stored RAT.

After performing operation <NUM>, the electronic device <NUM> may return to operation <NUM>, and may identify whether or not an available PLMN is found as a result of searching for a PLMN on the RAT other than the at least one stored RAT. The electronic device <NUM> may repeat operations <NUM> and <NUM> for a predetermined time or until an available PLMN is found.

Although <FIG> shows an example in which the electronic device <NUM> performs operation <NUM> after performing operations <NUM> and <NUM>, operation <NUM> may be performed regardless of operations <NUM> and <NUM> in sequence thereof. For example, operation <NUM> may be performed simultaneously with operation <NUM> or <NUM>, and may be performed after operation <NUM> or <NUM> is performed.

<FIG> illustrates another example of the operation <NUM> of an electronic device that searches for a PLMN according to various embodiments. This operation may be performed by the electronic device <NUM> shown in <FIG>, the electronic device <NUM> or the electronic device <NUM> shown in <FIG>, the electronic device <NUM> shown in <FIG>, or the processor <NUM> of the electronic device <NUM>.

Referring to <FIG>, in operation <NUM>, the electronic device <NUM> may identify whether or not there is RAT information stored in the memory <NUM>. According to various embodiments, if it is determined that a PLMN is required to be searched for, the electronic device <NUM> may identify whether or not there is RAT information stored in the memory <NUM>. For example, the electronic device <NUM> may identify whether or not there is RAT information stored in the memory <NUM> immediately after the electronic device <NUM> is turned off and then turned on. For example, the electronic device <NUM> may identify whether or not there is RAT information stored in the memory <NUM> immediately after recovering from the lack of coverage.

If there is RAT information stored in the memory <NUM>, the electronic device <NUM> may perform operation <NUM>. On the other hand, if there is no RAT information stored in the memory <NUM>, the electronic device <NUM> may perform operation <NUM>.

In operation <NUM>, in response to identifying that there is the stored RAT information, the electronic device <NUM> may search for a PLMN on at least one RAT included in the stored RAT information. In various embodiments, the electronic device <NUM> may search for an available PLMN using only the RF band of the at least one RAT. For example, although the electronic device <NUM> supports all of <NUM>, <NUM>, and <NUM> RATs, if the at least one RAT includes only <NUM>, the electronic device <NUM> may search for an available PLMN using only the RF band of <NUM>, excluding the RF bands of <NUM> and <NUM>.

In various embodiments, if an available PLMN is found as a result of searching for the PLMN on the at least one RAT, the electronic device <NUM> may register in the found PLMN in response thereto. The electronic device <NUM> may perform selection of a cell from among the cells of the found PLMN and location registration therein.

In operation <NUM>, in response to identifying that there is no stored RAT information, the electronic device <NUM> may search for a PLMN on all the RATs supported by the electronic device <NUM>. The electronic device <NUM> may search for an available PLMN using all the RF bands supported by the electronic device <NUM>. In various embodiments, if an available PLMN is found as a result of searching for the PLMN on all the supported RATs, the electronic device <NUM> may register in the found PLMN in response thereto. The electronic device <NUM> may perform selection of a cell from among the cells of the found PLMN and location registration therein.

In operation <NUM>, the electronic device <NUM> may identify whether or not registration is performed in the available PLMN as a result of the searching for the PLMN performed in operation <NUM> or <NUM>. If the registration is performed in the available PLMN as a result of searching for the PLMN, the electronic device <NUM> may perform operation <NUM>. On the other hand, if the registration fails in the available PLMN as a result of searching for the PLMN, the electronic device <NUM> may return to operation <NUM>, and may then search for a PLMN for all the RATs supported by the electronic device <NUM>. The electronic device <NUM> may repeat operations <NUM> and <NUM> for a predetermined period of time or until an available PLMN is found and registered.

In operation <NUM>, in response to the registration performed in the available PLMN as a result of searching for the PLMN, the electronic device <NUM> may identify RAT information supported by the registered PLMN. In various embodiments, the electronic device <NUM> may receive at least one system information message provided from the registered PLMN, and may identify at least one RAT supported by the registered PLMN, based on the received system information message.

In various embodiments, the system information message may include information in order for the electronic device <NUM> to access a specific cell controlled by a base station belonging to the registered PLMN and to operate properly. For example, the system information message may include a PLMN ID, a cell ID, RAT information, frequency information, and information related to cell reselection.

In various embodiments, in the case where the electronic device <NUM> performs cellular communication using the registered PLMN and an LTE or WCDMA RAT, the system information message may be used to transmit system information blocks (SIBs).

For example, in the case where the electronic device <NUM> performs cellular communication using the registered PLMN and an LTE RAT, the information related to cell reselection may be included in the system information message such as SIB5, SIB6, or SIB7. SIB5, SIB6, or SIB7 may include inter-frequency neighbor-cell information, WCDMA neighbor-cell information, and GSM neighbor-cell information, respectively. For example, in the case where the electronic device <NUM> performs cellular communication using the registered PLMN and a WCDMA RAT, information related to cell reselection may be included in the system information message such as SIB11, SIB12, or SIB19.

In various embodiments, the electronic device <NUM> may identify RAT information supported by the registered PLMN, based on the information related to the inter-frequency or inter-RAT cell reselection, which is included in the system information message. In various embodiments, the electronic device <NUM> may identify RAT information supported by the registered PLMN from information on the neighbor cell necessary for cell reselection, which is included in the system information message. For example, the electronic device <NUM> may determine the RAT served by the neighbor cell included in the system information message, thereby identifying RAT information supported by the registered PLMN.

For example, in the case where the electronic device <NUM> performs cellular communication using the registered PLMN and an LTE RAT, the electronic device <NUM> may identify RAT information supported by the registered PLMN, based on the system information message such as SIB5, SIB6, or SIB7 including information related to cell reselection. For example, if the electronic device <NUM> receives SIB5, and if SIB5 includes neighbor-cell information, the electronic device <NUM> may determine that the registered PLMN supports LTE. For example, if the electronic device <NUM> receives SIB6, and if SIB6 includes neighbor-cell information, the electronic device <NUM> may determine that the registered PLMN supports WCDMA. For example, if the electronic device <NUM> receives SIB7, and if SIB7 includes neighbor-cell information, the electronic device <NUM> may determine that the registered PLMN supports a GSM RAT.

For example, if the electronic device <NUM> performs cellular communication using the registered PLMN and a WCDMA RAT, the electronic device <NUM> may identify RAT information supported by the registered PLMN using the system information message, such as SIB11, SIB12, or SIB19, including information related to cell reselection.

For example, if the electronic device <NUM> performs cellular communication using the registered PLMN and a GSM RAT, the electronic device <NUM> may identify RAT information supported by the registered PLMN, based on an SI2 quarter message including information related to cell reselection.

In various embodiments, the electronic device <NUM> may identify RAT information supported by the registered PLMN, based on information related to scheduling of system information blocks (SIBs), which is included in the system information message. For example, if the electronic device <NUM> performs cellular communication using the registered PLMN and an LTE RAT, the electronic device <NUM> may identify RAT information supported by the registered PLMN, from a list of SIBs to be transmitted, which is included in SIB1. For example, if SIB5, SIB6, or SIB7 is included in the list of SIBs to be transmitted, which is included in SIB1, the electronic device <NUM> may determine LTE, WCDMA, or GSM to be the RAT supported by the registered PLMN in each case. Alternatively, if SIB6 or SIB7 is not included in the list of SIBs to be transmitted, the electronic device <NUM> may determine WCDMA or GSM to be the RAT that is not supported by the registered PLMN in each case.

In operation <NUM>, based on identification of the RAT information supported by the registered PLMN, the electronic device <NUM> may store the RAT information supported by the registered PLMN in order to use the same in searching for a PLMN. For example, the electronic device <NUM> may update existing RAT information with the RAT information supported by the registered PLMN. In various embodiments, the electronic device <NUM> may store the RAT information supported by the registered PLMN in the memory <NUM>. In various embodiments, the stored RAT information may be maintained without being deleted even while power is not supplied to the electronic device <NUM>.

As described above, a method of an electronic device (e.g., the electronic device <NUM>) according to various embodiments may include: performing camp-on on a cell of a first base station; receiving, from the first base station, information related to a network related to the first base station, identifying a state in which no service is provided from the first base station to the electronic device, and searching for a registered public land mobile network (RPLMN), based at least in part on the received information.

In various embodiments, the information related to the network may include at least one system information block (SIB), and the at least one SIB may include radio access technology (RAT) information, which is supported by the network. In various embodiments, the searching for the RPMN may include searching for the RPLMN using the RAT information supported by the network. In various embodiments, the method may include storing the RAT information in the memory and, if the network information is changed, updating the RAT information.

In various embodiments, the method may further include, if the RPLMN is not found by searching for the RPLMN, searching for an HPLMN using RAT information supported by the electronic device. In various embodiments, the method may further include, if the HPLMN is not found by searching for the HPLMN, searching for a PLMN available for the electronic device.

A method for operating an electronic device according to various embodiments described above may include: performing camp-on on a cell of a first base station, storing information related to a network, which is received from the first base station, and if the electronic device is rebooted after storing the information, searching for a registered public land mobile network (RPLMN), based at least in part on the stored information.

As described above, a method for operating an electronic device (e.g., the electronic device <NUM>) in a wireless communication system according to various embodiments may include receiving at least one system information message, identifying at least one RAT among a plurality of radio access technologies (RATs) supported by the electronic device, based on the at least one system information message, and searching for a public land mobile network (PLMN) on the at least one RAT.

In various embodiments, the method may further include storing at least one identified RAT in order to use the same in searching for a PLMN. In some embodiments, the method may further include switching the electronic device from a turn-off state to a turn-on state after storing the at least one RAT, in response to the switching, searching for a PLMN on the at least one stored RAT, and in response to identifying that the searching for the PLMN fails, searching for a PLMN on a RAT other than the at least one stored RAT among the plurality of RATs. In some embodiments, the method may further include: identifying interruption of communication service for the electronic device after storing the at least one RAT; in response to the identification, searching for a PLMN on the at least one stored RAT; and in response to identifying that the searching for the PLMN fails, searching for a PLMN on a RAT other than the at least one stored RAT among the plurality of RATs.

In various embodiments, the method may further include, in response to identifying that the searching for the PLMN on the at least one RAT fails, searching for a PLMN on a RAT other than the at least one RAT among the plurality of RATs.

In various embodiments, the method may further include: if an available PLMN is found as a result of searching for the PLMN on the at least one RAT, registering in the found PLMN in response thereto; in response to the registration, identifying at least one RAT supported by the registered PLMN, based on the system information message of the registered PLMN; and storing the at least one RAT supported by the registered PLMN.

In various embodiments, the searching for the PLMN on the at least one RAT may be searching for the PLMN in which the electronic device most recently registered (registered PLMN).

As described above, a method for operating an electronic device (e.g., the electronic device <NUM>) in a wireless communication system according to various embodiments may include: identifying whether or not RAT information supported by a PLMN is stored in the electronic device; if the RAT information is stored in the electronic device, searching for a public land mobile network (PLMN) on at least one RAT included in the stored RAT information; in response to registration of the electronic device in an available PLMN, identifying RAT information supported by the registered PLMN; and, based on the identification, storing the RAT information supported by the registered PLMN.

Claim 1:
An electronic device supporting a plurality of radio access technologies, RATs, the electronic device comprising:
a memory;
a communication circuit; and
at least one processor operatively coupled to the memory and the communication circuit,
wherein the at least one processor is configured to:
receive (<NUM>) at least one system information message through the communication circuit,
identify (<NUM>) at least one RAT among the plurality of RATs, based on the at least one system information message,
search (<NUM>) for a first public land mobile network, PLMN, on the at least one RAT,
register (<NUM>) and select the first PLMN on the at least one RAT,
perform a location registration on a cell among cells of the first PLMN,
in response to performing the location registration, store (<NUM>) the at least one RAT in the memory for using when searching for a second PLMN,
in response to identifying interruption of a communication service, search (<NUM>) for the second PLMN on the at least one RAT stored in the memory,
in case that the electronic device finds the second PLMN on the at least one RAT stored in the memory:
register (<NUM>) the second PLMN, and
perform a location registration on a cell among cells of the second PLMN, and
in case that the electronic device fails to find the second PLMN on the at least one RAT stored in the memory, search for an available PLMN on RATs other than the at least one RAT stored in the memory among the plurality of RATs during a predetermined time.