Method and User Equipment for Recovering from Connectivity Problems

Abstract

A method for managing efficient services from a public land mobile network performed by a user equipment and a user equipment for managing efficient services from a public land mobile network are provided. The method includes: detecting an interruption of a radio resource connection with a first public land mobile network, the first public land mobile network being associated with at least one first parameter, the interruption resulting in loss of access to at least one type of service from the first public land mobile network; adding, during a defined time period, the at least one first parameter, the at least one type of service, and the defined time period to a list; and detecting, within the defined time period, a second public land mobile network associated with at least one second parameter, the second public land mobile network providing access to the at least one type of service, the at least one second parameter being different from the at least one first parameter.

Description

Technical Field

[0001] Some example embodiments of the present disclosure relate to wireless network connectivity, and more particularly, to methods and user equipment for recovering from abnormal scenarios that cause connectivity issues between a Public Land Mobile Network (PLMN) and a User Equipment (UE). Background Art

[0002] Currently, a User Equipment (UE) is configured to delete Registered Public Land Mobile Network (RPLMN) and Equivalent PLMN (EPLMN) information when a Radio Resource (RR) connection is released due to abnormal scenarios on the PLMN side and / or the UE side. The UE deletes information including parameters associated with the PLMN, such as Location Area Identification (LAI), Temporary Mobile Subscriber Identity (TMSI), key sequence number, etc.; these parameters are stored in the Subscriber Identity Module / Universal Mobile Telecommunications System (UMTS) Subscriber Identity Module (SIM / USIM). Examples of abnormal scenarios that cause RR connection release include (but are not limited to) network failures, registration request transmission failures, congestion, and no response to the UE's registration request.

[0003] The UE deletes the above information based on guidelines specified in the specifications of the 3rd Generation Partnership Project (3GPP). Subsequently, the UE enters an idle state for PLMN search and / or selection. In a Long Term Evolution (LTE) scenario, since the RPLMN and PLMN in the EPLMN list are deleted, the UE may disable the evolved Universal Terrestrial Radio Access (eUTRA) capability. In such a case, the UE can only operate in a second generation (2G) or third generation (3G) Radio Access Technology (RAT) mode. If the network selection is set to the automatic mode, the UE performs PLMN selection to search for a PLMN that provides both Circuit Switched (CS) services and Packet Switched (PS) services. If the network selection is set to the manual mode, access to the UE's services is restricted until the user changes the PLMN selection mode to the automatic mode or the user selects a different PLMN. Summary of the Invention

[0004] Accordingly, some example embodiments provide a method, performed by a user equipment (UE), for managing efficient services from a public land mobile network (PLMN). The method includes: detecting an interruption of a radio resource (RR) connection with a first PLMN, the first PLMN being associated with at least one first parameter, the interruption causing a loss of access to at least one type of service from the first PLMN. The method includes: adding, during a defined time period, the at least one first parameter, the at least one type of service, and the defined time period to a list. The method includes: detecting, within the defined time period, a second PLMN associated with at least one second parameter, the second PLMN providing access to the at least one type of service, the at least one second parameter being different from the at least one first parameter.

[0005] Some example embodiments provide a user equipment (UE) for managing efficient services from a public land mobile network (PLMN). The UE includes: a receiver configured to detect an interruption of a radio resource (RR) connection with a first PLMN, the first PLMN being associated with at least one first parameter, the interruption causing a loss of access to at least one type of service from the first PLMN; and at least one processor configured to add, during a defined time period, the at least one first parameter, the at least one type of service, and the defined time period to a list. The receiver is further configured to: detect, within the defined time period, a second PLMN associated with at least one second parameter, the second PLMN providing access to the at least one type of service, the at least one second parameter being different from the at least one first parameter.

[0006] These and other aspects of the example embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. However, it should be understood that, although some example embodiments and many of their specific details are indicated, the following description is given by way of illustration and not limitation. Many changes and modifications may be made within the scope of the example embodiments herein without departing from their spirit, and the example embodiments herein include all such modifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Some example embodiments are shown in the drawings, wherein like reference numerals represent corresponding parts in the various drawings. The example embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0008] Figure 1 A block diagram of a UE for recovering from an abnormal scenario that causes a release of an RR connection between a PLMN and the UE, according to some example embodiments disclosed herein, is shown;

[0009] Figure 2is a flowchart showing a method performed by a UE for recovering from an abnormal scenario that causes an RR connection release between a PLMN and the UE according to some example embodiments disclosed herein;

[0010] Figures 3a to 3c shows an example scenario according to some example embodiments disclosed herein, where the UE registers with a PLMN after the PLMN stops providing CS services and / or PS services to the UE;

[0011] Figures 4a to 4c shows an example scenario according to some example embodiments disclosed herein, where the UE registers with a first PLMN after a second PLMN stops providing one of CS services and PS services to the UE, while the UE receives the other of PS services and CS services from the second PLMN; and

[0012] Figures 5a to 5d shows an example scenario according to some example embodiments disclosed herein, where the UE maintains access to several types of services by keeping RPLMN information and / or PLMN information in the EPLMN list. DETAILED DESCRIPTION

[0013] With reference to the non - limiting example embodiments shown in the drawings and detailed below, the example embodiments herein and their various features and advantageous details are more fully explained. Descriptions of well - known components and processing techniques are omitted so as not to unnecessarily obscure some example embodiments herein. The examples used herein are only intended to facilitate an understanding of the manner in which the example embodiments herein can be practiced and further enable those skilled in the art to practice the example embodiments herein. Therefore, the examples should not be construed as limiting the scope of the example embodiments herein.

[0014] Some example embodiments of the present disclosure disclose methods and user equipment for enabling recovery from an abnormal scenario that occurs at a public land mobile network (PLMN) and / or user equipment (UE), such that a radio resource (RR) connection between the PLMN and the UE is released. The abnormal scenario may also result in a rejection of a registration request sent from the UE to the PLMN, such that the UE can register with the PLMN. Example embodiments include maintaining a list that includes: at least one PLMN and parameters associated with the at least one PLMN, a defined time period for which the at least one PLMN is to be stored in the list, and services not provided by the at least one PLMN (e.g., packet switched (PS) and / or circuit switched (CS)). The defined time period may refer to a dynamically configurable value. When the PLMN does not send a registration acceptance message in response to a previous registration attempt by the UE to indicate that the PLMN is ready to provide CS, PS, or both CS and PS, the UE may avoid registration attempts with the PLMN throughout the defined time period. When the RR connection between the PLMN and the UE is suspended, the UE may also avoid registration attempts with the PLMN throughout the defined time period.

[0015] The parameters include a PLMN identification code of the at least one PLMN, a tracking area code (TAC) and / or a location area code (LAC) of the at least one PLMN, etc. Example embodiments include performing a PLMN search in the list excluding the at least one PLMN during a period similar to or the same as the defined time period. Once the time period expires, the at least one PLMN may be considered for the PLMN search. Example embodiments include detecting a PLMN within the defined time period for receiving at least one of PS service and CS service.

[0016] Example embodiments include performing a PLMN search to detect a PLMN that can provide both PS service and CS service, while receiving PS service or CS service from a registered PLMN (RPLMN). Example embodiments include saving the RPLMN and the PLMN in an equivalent PLMN (EPLMN) list, and performing a selection of the PLMNs included in the EPLMN list for receiving PS service and / or CS service on different radio access technologies (RATs).

[0017] Some example embodiments of the present disclosure provide methods and user equipment for enabling recovery from an abnormal scenario that occurs at a public land mobile network (PLMN) and / or user equipment (UE), resulting in a release of a radio resource (RR) connection between the PLMN and the UE.

[0018] Some example embodiments of the present disclosure provide a maintenance list that includes: at least one PLMN having at least one associated parameter, such as a PLMN identification code of the at least one PLMN and a tracking area code (TAC) and / or a location area code (LAC) of the at least one PLMN; a time period during which the at least one PLMN is to be stored in the list; and services (such as packet switched (PS) and / or circuit switched (CS)) not provided (or rejected) by the at least one PLMN, wherein once the time period expires, connection can be made to the at least one PLMN in the PLMN list.

[0019] Some example embodiments of the present disclosure provide for performing a PLMN search and detecting a PLMN that can provide both PS services and CS services while receiving PS services or CS services from a registered PLMN (RPLMN).

[0020] Some example embodiments of the present disclosure provide for saving the RPLMN and PLMN in an equivalent PLMN (EPLMN) list and performing a selection of the PLMNs included in the EPLMN list for receiving PS services and / or CS services on different radio access technologies (RATs).

[0021] Now referring to the drawings, and more specifically, to Figures 1 to 5d , in which, throughout the drawings, like reference numerals always denote corresponding features, some example embodiments are shown.

[0022] Figure 1Shows the various units of the UE 100 for recovering from an abnormal scenario that causes the release of the RR connection between the PLMN and the UE 100. The UE 100 includes a transmitter 101, a receiver 102, at least one processor 103 (also referred to herein as the singular "processor 103"), and a memory 104 (also referred to herein as the "component" of the UE 100). The UE 100 may refer to a terminal device, a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a user station (SS), a wireless device, or a handheld device. The UE 100 may be capable of operating in different RATs. According to some example embodiments, the operations performed by any one or all of the transmitter 101, the receiver 102, at least one processor 103, and the UE 100 described herein may be executed by at least one processor (e.g., at least one processor 103) running program code including instructions corresponding to the operations. The instructions may be stored in the memory of the UE 100 (e.g., memory 104). As used in this disclosure, the term "processor" may refer to, for example, a hardware-implemented data processing device having a physically configured circuit to perform desired operations, the operations including, for example, operations represented as code and / or instructions included in a program. In at least some example embodiments, the above-mentioned hardware-implemented data processing device may include (but is not limited to) a microprocessor, a central processing unit (CPU), a processor core, a multi-core processor, a multi-processor, an application-specific integrated circuit (ASIC), and a field-programmable gate array (FPGA).

[0023] The transmitter 101 may send a registration request to one or more PLMNs (e.g., by sending a location area update) to receive PS services and / or CS services. For example, the transmitter 101 may send the registration request to a base station connected to the corresponding one or more PLMNs. Operations performed by the PLMN and / or RPLMN described herein may be performed by a base station connected to the PLMN and / or RPLMN. The base station may refer to a Node B, evolved Node B (eNB), sector, site, base transceiver system (BTS), access point (AP), relay node, remote radio head (RRH), radio frequency unit (RU), or cell. According to some example embodiments, the BS or cell may refer to a function or area covered by a base station controller (BSC) in code division multiple access (CMDA), a Node B in wideband CDMA (WCDMA), an eNB or sector in long term evolution (LTE), and may include a giant cell, macro cell, micro cell, pico cell, femto cell, and / or various coverage areas, e.g., the coverage range of a relay node, RRH, RU, or cell. The UE 100 may send an uplink signal to the RPLMN via the transmitter 101. In an example, the RPLMN is considered as the first PLMN. The receiver 102 may detect the occurrence of an abnormal scenario at the UE 100 and / or at the RPLMN that causes the release of the RR connection between the UE 100 and the RPLMN. The UE 100 may receive downlink information from the RPLMN (e.g., from a base station connected to the RPLMN) via the receiver 102.

[0024] The UE 100 may communicate with a base station on a wireless communication network (e.g., receive signals from and / or send signals to the base station). The wireless communication network may refer to fifth generation wireless (5G), long term evolution (LTE), LTE-Advanced, CDMA, global system for mobile communications (GSM), wireless local area network (WLAN), or other wireless communication networks. Information may be communicated via the wireless communication network in various multiple access ways, such as code division multiple access (CMDA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), orthogonal frequency division multiple access multiplexing (OFDM) FDMA (OFDM-FDMA), OFDM-TDMA, or OFDM-CDMA.

[0025] The processor 103 may interact with the receiver 102 to determine whether an abnormal scenario has occurred that causes the release of the RR connection between the RPLMN and the UE 100. The abnormal scenario may occur at the UE 100 and / or at the PLMN. The abnormal scenarios include (but are not limited to) the PLMN rejecting the registration request of the UE 100 due to network failure, congestion, etc.; the registration request of the UE 100 failing to be sent; no response from the PLMN to the registration request of the UE 100, etc. The processor 103 may add information to a list that includes at least one parameter associated with the at least one PLMN. The list may be stored in the memory 104. The list may include the at least one parameter associated with the at least one PLMN, one or more types of services not provided by the at least one PLMN, and a defined time period. The at least one parameter associated with the at least one PLMN may be the identification code of the PLMN, the TAC and / or LAC of the PLMN, etc. The processor 103 may store, in the memory 104 during the defined time period, the at least one parameter associated with the at least one PLMN, one or more types of services not provided by the at least one PLMN, and the defined time period.

[0026] In an example, the RPLMN is considered as the first PLMN. The receiver 102 may detect the occurrence of an abnormal scenario at the first PLMN and / or at the UE 100, such as the first PLMN rejecting the registration request of the UE 100 due to network failure and / or congestion, etc., the registration request of the UE 100 failing to be sent, no response to the registration request, etc. Due to the occurrence of at least one abnormal scenario, the RR connection between the first PLMN and the UE 100 may be interrupted. Therefore, the first PLMN may not be able to provide PS services and / or CS services.

[0027] The receiver 102 may indicate to the processor 103 the occurrence of the at least one abnormal scenario. Subsequently, the processor 103 may add one or more parameters associated with the first PLMN to the list, such as the identification code of the first PLMN, the LAC and / or TAC of the first PLMN, one or more types of services not provided by the first PLMN, and the defined time period.

[0028] The defined time period represents the time period during which the parameters of the first PLMN will be stored in the first list. In one example, the identification code of the first PLMN may be PLMN A, and the LAC / TAC may be (EFF3) H, the first PLMN can stop providing (e.g., stop supplying) CS services, and the limited time period for which the parameters of the first PLMN are stored in the list can be 12 minutes. The entry added to the list by the processor 103 can be: PLMN A / EFF3 / CS / 12.

[0029] The receiver 102 can detect a second PLMN to receive CS services. The detection process can be controlled by the at least one processor 103, wherein at least one parameter of the second PLMN can be different from the parameters of the first PLMN. Examples of different parameters of PLMNs can be represented as PLMN A / EFF4 / CS, PLMN B / F22E / CS, PLMN B / EFF3 / CS, etc.

[0030] The receiver 102 attempts to detect the second PLMN within a limited time period (e.g., 12 minutes). Once the limited time period ends (e.g., 12 minutes end), the processor 103 can delete the parameters of the first PLMN stored in the list. Then, in order to receive CS services, the first PLMN can be considered for detection again.

[0031] This example can be extended to a scenario where the first PLMN stops (e.g., stops providing and / or supplying) PS services and / or the first PLMN stops both PS services and CS services. An example entry added to the list for the former scenario can be PLMNA / EFF3 / PS / 12, and for the latter scenario can be PLMN A / EFF3 / PS and CS / 12.

[0032] In some example embodiments, if the first PLMN rejects (e.g., stops providing and / or supplying) CS services, the receiver 102 detects the second PLMN to receive both CS services and PS services, while receiving PS services from the first PLMN. Similarly, if the first PLMN rejects PS services, the receiver 102 detects the second PLMN to receive both CS services and PS services, while receiving CS services from the first PLMN.

[0033] In some example embodiments, in the case where the RPLMN stops providing services to the UE 100 due to the occurrence of an abnormal scenario, the processor 103 can hold the parameters of the RPLMN and / or PLMN included in the EPLMN list in the memory 104.

[0034] Figure 1FIG. 0 shows example components of UE 100, but it is to be understood that some example embodiments are not limited thereto. In some example embodiments, UE 100 may include fewer or more components. Additionally, the labels or names of the components are for illustrative purposes only and do not limit the example embodiments. One or more components may be combined together to perform the same or substantially similar functions in UE 100.

[0035] Figure 2 FIG. 4 shows a flowchart 200 of a method performed by UE 100 to recover from an abnormal scenario that causes the release of the RR connection between the PLMN and UE 100.

[0036] At operation 201, the method includes determining a first PLMN capable of providing both PS services and CS services. Upon detecting the first PLMN, UE 100 may register with the first PLMN. Thereafter, UE 100 may receive PS services and / or CS services from the first PLMN. While receiving PS services and / or CS services from the first PLMN, at operation 202, UE 100 may determine that an abnormal scenario has occurred at the first PLMN, at UE 100, or at both the first PLMN and UE 100. Due to the occurrence of the abnormal scenario, the corresponding services may be interrupted because the first PLMN refuses to provide (e.g., stop providing or supplying) PS services or CS services or both PS services and CS services to UE 100.

[0037] Once UE 100 determines in operation 202 that an abnormal scenario has occurred, the method includes: at operation 203, storing parameters associated with the first PLMN in a list. In some example embodiments, the parameters include the identification code of the first PLMN, TAC, LAC, etc. The parameters associated with the first PLMN may be stored in the list for a predetermined period of time. At operation 204, the method includes detecting a second PLMN capable of providing both PS services and CS services. UE 100 attempts to detect the second PLMN within a predetermined period of time, where at least one parameter associated with the second PLMN is different from at least one parameter associated with the first PLMN. Thus, at least one of the PLMN identification code, LAC, TAC, etc. of the second PLMN is different from the first PLMN. According to some example embodiments, if the first PLMN only stops supplying one of the PS services and CS services, the method further includes: while detecting the second PLMN in operation 204, continuing to receive services (e.g., the other of the PS services and CS services) from the first PLMN. At operation 205, the method includes UE 100 registering with the second PLMN.

[0038] After the expiration of a defined time period, parameters associated with the first PLMN can be removed from the list, and the first PLMN can be detected and considered for registration. In some example embodiments, if the second PLMN has a lower priority compared to the first PLMN, the UE 100 can attempt to detect the first PLMN (and register with the first PLMN) to receive PS services and CS services. According to some example embodiments, the UE 100 can attempt to detect the first PLMN only after the expiration of the defined time period.

[0039] Figures 3a to 3c An example scenario is shown where the UE 100 can register with a PLMN (e.g., PLMN A) that has previously stopped supplying CS services and / or PS services to the UE 100. In this scenario, the network selection in the UE 100 is set to the automatic mode. Considering the UE 100 in a specific location can attempt to register with PLMN A having an LAC (1234) H As Figure 3a shown, the UE 100 can send a Location Area Update (LAU) to PLMN A to register with PLMN A. Due to the occurrence of an abnormal scenario, PLMN A may not respond to the registration request, or PLMN A can reject the registration request.

[0040] If it is considered that the UE 100 was receiving at least one of PS and CS, the occurrence of an abnormal scenario at the UE 100 and / or PLMN A can cause PLMN A to stop providing both PS services and CS services.

[0041] In this case, a conventional UE deletes the parameters associated with PLMN A (e.g., parameters associated with the PLMN such as Location Area Identity (LAI), Temporary Mobile Subscriber Identity (TMSI), key sequence number, etc.) in accordance with 3GPP specifications. However, in some example embodiments, the UE 100 can add the identification code and LAC of PLMN A to the list stored at the UE 100. The UE 100 can set a first defined time period during which the UE 100 can exclude PLMN A having an LAC (1234) H while performing a PLMN search to detect another PLMN. After the expiration of the first defined time period, the UE100 can re-attempt to re-register with PLMN A having an LAC (1234) H Other parameters associated with PLMN A (such as the first defined time period and the services stopped by PLMN A (e.g., PS services and / or CS services)) can also be included in the list.

[0042] Before the expiration of the first defined time period, the UE 100 continues PLMN search to detect a PLMN that can provide both PS services and CS services. As Figure 3b shown, when detecting a PLMN B with LAC (5678) H and providing both PS services and CS services, the UE 100 may send a registration request to the PLMN B with LAC (5678) H . In this example, an abnormal scenario has occurred at the UE 100 and / or the PLMN B. Thus, the PLMN B may reject the registration request of the UE 100. In such a case, a conventional UE will delete the information associated with the PLMN B according to the 3GPP specification. However, according to some example embodiments, after detecting that the PLMN B rejects the registration request, the UE 100 may update the list by adding the identification code and LAC of the PLMN B to the list. Similarly, the UE 100 may set a second defined time period during which the UE 100 may exclude the PLMN B with LAC (5678) H while performing PLMN search to detect another PLMN. After the expiration of the second defined time period, the UE 100 may re-attempt to register with the PLMN B with LAC (5678) H .

[0043] As Figure 3c shown, before the expiration of the first defined time period, the UE 100 may re-attempt to register with the PLMN A (but with LAC (ABCD) H ). The UE 100 may successfully register with the PLMN A because the LACs are different. Although the PLMN identification codes are the same (e.g., PLMN A), if the LACs are different and the information about the PLMN A has not been deleted from the UE 100, the UE 100 may successfully register. After the expiration of the first defined time period or after the expiration of the second defined time period, the UE 100 may also re-attempt to register with the PLMN A with LAC (1234) H or the PLMN B with LAC (5678) H because the information about the PLMN A and the PLMN B is stored in the UE 100.

[0044] A conventional UE cannot successfully register with a PLMN and / or an RPLMN after an abnormal scenario occurs because the conventional UE deletes information associated with the PLMN and / or the RPLMN in response to the abnormal scenario. When the conventional UE successfully registers with a new PLMN, the registration information about the old PLMN (where an abnormal scenario may have occurred) is replaced with the registration information about the new PLMN. The registration information may include at least one of the following: Location Area Identifier (LAI), Routing Area Identifier (RAI), Tracking Area Identifier (TAI), security keys exchanged during the registration process, etc. This results in a situation where the conventional UE repeatedly attempts to register with the same PLMN and / or RPLMN, and it is impossible to successfully register with these same PLMNs and / or RPLMNs. For example, the conventional UE may repeatedly perform the following operations: attempt to register with PLMN B after failing to register with PLMN A, and attempt to register with PLMN A after failing to register with PLMN B. The negative consequences of this situation include the UE lacking access to PS services and / or CS services, the UE being unable to register with a higher-priority PLMN, and the UE consuming excessive power. However, according to some example embodiments, the UE 100 is improved compared to the conventional UE by storing a list of parameters including the PLMN (with which the UE has experienced a failed registration). By storing the information of such PLMNs, the UE 100 can later successfully register with these same PLMNs, thereby avoiding the lack of access to PS services and / or CS services, the inability to register with a higher-priority PLMN, and the excessive power consumption experienced by the conventional UE.

[0045] Figures 4a to 4c An example scenario is shown where the UE 100 registers with a PLMN (e.g., PLMN B) that provides CS services and PS services while receiving PS services or CS services from another PLMN (e.g., PLMN A). In this scenario, the network selection in the UE 100 is set to the automatic mode. Initially, the UE 100 at a specific location may attempt to register with PLMN A having an LAC (1234) H The PLMN A having an LAC (1234) H may accept the registration request and provide PS services and CS services to the UE 100. As Figure 4a shown, at a specific instant, PLMN A may stop providing CS services due to the occurrence of an abnormal scenario. In this case, the UE 100 may exclude the PLMN A with an LAC (1234) while performing a PLMN search with the LAC and identifier of PLMN A, and the UE 100 HThe first limited time period of PLMN A and one or more types of services not provided by PLMN A (e.g., CS) are added to the list stored at UE 100. After the expiration of the first limited time period, UE 100 may re-attempt to register with PLMN A having LAC (1234) H to receive CS services.

[0046] As Figure 4b shown, UE 100 may continue PLMN searching within the first limited time period to detect another PLMN that can provide both PS services and CS services. While UE 100 continues to receive PS services from PLMN A having LAC (1234) H , PLMN searching may be performed. UE 100 may send a registration request to PLMN B having LAC (5678) H . Due to an abnormal scenario occurring at UE 100 and / or PLMN B, PLMN B having LAC (5678) H may reject the registration request of UE 100. Thereafter, UE100 may update the list by adding the identification code and LAC of PLMN B to the list. UE 100 may set a second limited time period during which UE 100 may exclude PLMN B having LAC (5678) H while performing PLMN searching. After the expiration of the second limited time period, UE 100 may re-attempt to register with PLMN B having LAC (5678) H .

[0047] As Figure 4c shown, before the expiration of the second limited time period, UE 100 may re-attempt to register with PLMN B (but having LAC (3456) H ). UE 100 may successfully register with PLMN B because the LAC is different. Although the identification code of the PLMN is the same (e.g., PLMN B), if the LAC is different and the information about PLMN B has not been deleted from UE 100, UE100 may successfully register. After the expiration of the first limited time period or after the expiration of the second limited time period, UE 100 may also re-attempt to register with PLMN A having LAC (1234) H or PLMN B having LAC (5678) H because the information about PLMNA and PLMN B is stored in the list in UE 100.

[0048] According to some example embodiments, since UE 100 sends to PLMN B having LAC (3456)H The registration request for PLMN B is successful. Therefore, even if the priority of PLMN B is lower than that of PLMN A, UE 100 may not attempt to register with PLMN A with LAC (ABCD) H or PLMN A with LAC (1234) H When registering successfully with the PLMN with LAC (3456), UE 100 stops receiving PS services from PLMN A with LAC (1234), thus reducing or preventing UE 100 from switching back and forth between PLMN A and PLMN B, enabling UE 100 to save a significant amount of battery. H When registering successfully with the PLMN with LAC (3456), UE 100 stops receiving PS services from PLMN A with LAC (1234) H of PLMN A.

[0049] Figures 5a to 5d FIG. shows an example scenario in which UE 100 can have access to several types of services by maintaining RPLMN information and PLMN information within an EPLMN list stored at UE 100. In this scenario, the network selection in UE 100 is set to manual. UE 100 can receive services from a specific service provider (SP). UE 100 can be located in an area where UE 100 can receive services from SP1 or SP2. SP1 and SP2 can be included in the EPLMN list. In one example, consider UE 100 receiving services from SP3. SP3 can have an agreement with SP1 and SP2 to provide services to users of SP3. UE 100 is not in the coverage area of SP3 but in the coverage areas of SP1 and SP2. Since SP3 has an agreement with SP1 and SP2, UE 100 can receive services of different RATs from at least one of SP1 and SP2. Therefore, SP1 and SP2 are included in the EPLMN list. As Figure 5a shown, initially, UE 100 can receive 2G services from SP1. The RPLMN at this stage can be SP1 because UE 100 has registered with SP1 to receive 2G services. In accordance with the 3GPP specification guidelines, UE 100 can perform a PLMN search, and as Figure 5b shown, UE 100 can connect (e.g., register) with SP2 to receive 3G services. The RPLMN at this stage can be SP2 because UE 100 has registered with SP2 to receive 3G services.

[0050] In one example (not shown), if SP1 stops providing 2G services due to the occurrence of an abnormal scenario, the UE 100 can save the information of SP1 (RPLMN) in the EPLMN list. This is different from a conventional UE that deletes the information of SP1 if SP1 stops providing 2G services. The information about SP1 can be included in the list stored at the UE 100 during a limited time period.

[0051] As Figure 5c shown, SP2 may refuse to provide (e.g., stop providing or supplying) 3G services to the UE 100 due to the occurrence of an abnormal scenario. When SP2 prohibits (e.g., refuses or stops) 3G services according to the 3GPP specification guidelines, a conventional UE deletes the RPLMN (i.e., SP2). Due to the deletion of the RPLMN (SP2), all PLMNs in the EPLMN list are deleted; for example, with the deletion of SP2, SP1 is also deleted. The UE 201 can thus not connect to SP1 or SP2. The UE 201 can only receive limited services.

[0052] However, according to some example embodiments, when SP2 prohibits (e.g., refuses or stops) 3G services, the UE 100 can avoid deleting the information of SP2 from the EPLMN list (e.g., such as those parameters discussed above with reference to Figures 3a to 4c ). The information about SP2 can be included in the list stored at the UE 100 during a limited time period. During the limited time period, the UE 100 can avoid registering with SP2 in order to receive 3G services. Due to saving the information of SP1 and SP2 in the EPLMN list, the UE 100 can attempt to register with the PLMN (e.g., SP1) included in the EPLMN list to receive PS services and / or CS services on the same RAT (2G) or a different RAT (3G). As Figure 5d shown, the UE 100 can register with SP1 again and receive 2G services. In addition, once the limited time period has expired, the UE 100 can re-attempt to register with PLMN B to receive 3G services. Thus, according to some example embodiments, the UE 100 is improved compared to a conventional UE by storing a list including the information of the RPLMN and / or PLMN (e.g., Figure 5d SP1 and SP2 therein) after a failed registration. By storing the RPLMN and / or PLMN information, the UE 100 can later successfully register with the same RPLMN and / or PLMN, thereby enabling access to several types of services (as opposed to the limited services accessible by a conventional UE).

[0053] The example embodiments disclosed herein can be implemented by at least one software program that runs on at least one hardware device and performs network management functions to control components.Figure 1 The components shown in [Figure] include blocks, which can be at least one of the hardware devices, or a combination of hardware devices and software modules.

[0054] The exemplary embodiments disclosed herein describe methods and UEs for recovering from abnormal scenarios that result in the release of the connection between the network and the UE. Therefore, it should be understood that when program code for implementing one or more operations of the method is executed on a server, a UE, or any suitable programmable device, the scope of protection extends to the computer-readable medium containing the program code. In some exemplary embodiments, the method is implemented or implemented in conjunction with the following: a software program written in, for example, Very High Speed Integrated Circuit Hardware Description Language (VHDL) (or another programming language); or a software program implemented by one or more VHDLs, or several software modules executed on at least one hardware device. The at least one hardware device can be any kind of portable programmable device. The at least one hardware device can also include hardware (such as an ASIC) or a combination of hardware and software (such as an ASIC and an FPGA) or at least one microprocessor that executes one or more software modules stored in at least one memory. The exemplary embodiments described herein can be implemented partly in hardware and partly in software. Alternatively, the exemplary embodiments can be implemented, for example, using multiple CPUs on different hardware devices.

[0055] The foregoing description of some exemplary embodiments will so fully reveal the general nature of the exemplary embodiments herein that others can, by applying current knowledge, readily modify and / or adapt various applications of some exemplary embodiments without departing from the general concept, and, accordingly, such adaptations and modifications should and are intended to be included within the meaning and range of equivalents of the exemplary embodiments. It should be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Thus, although some exemplary embodiments of the present disclosure have been described, those skilled in the art will recognize that the exemplary embodiments herein can be practiced with modifications within the spirit and scope of the exemplary embodiments as described herein.

[0056] The various operations of the above method can be performed by any suitable device capable of performing the operations, such as various hardware and / or software implemented in some form of hardware (such as a processor, an ASIC, etc.).

[0057] The software can include an ordered list of executable instructions for implementing logical functions, and can be embodied in any "processor-readable medium" for use by or in connection with an instruction execution system, apparatus, or device (such as a single or multiple core processor or a system including a processor).

[0058] The blocks or operations of the methods or algorithms and functions described in connection with the exemplary embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. If implemented in software, the functions may be stored on or transmitted through a tangible, non-transitory computer-readable medium as one or more instructions or code. The software modules may reside in random access memory (RAM), flash memory, read-only memory (ROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Claims

1. A method for managing valid services from a public land mobile network, performed by a user equipment, the method comprises: detecting a first public land mobile network associated with a first value of a plurality of parameters; registering with the first public land mobile network; detecting an interruption of a radio resource connection with the first public land mobile network, the interruption causing loss of access to at least one type of service from the first public land mobile network; when the interruption is detected, adding the first value, the at least one type of service, and a defined time period for preventing re-detection of the first public land mobile network to a list; and detecting a second public land mobile network associated with a second value of the plurality of parameters within the defined time period, the second public land mobile network providing access to the at least one type of service, wherein detecting a second public land mobile network associated with a second value of the plurality of parameters within the defined time period comprises: before the defined time period expires, re-detecting the first public land mobile network associated with a third value of the plurality of parameters based on at least one of the first values that is different from at least one of the third values in the list.

2. The method according to claim 1, wherein the plurality of parameters includes an identification code of the public land mobile network, and at least one of a location area code and a tracking area code.

3. The method according to claim 1, wherein the interruption of the radio resource connection includes not receiving a response to a registration request of the user equipment from the first public land mobile network.

4. The method according to claim 1, wherein the at least one type of service is a packet switched service, and the method further comprises: receiving a circuit switched service from the first public land mobile network while detecting the second public land mobile network.

5. The method according to claim 1, wherein the at least one type of service is a circuit switched service, and the method further comprises: receiving a packet switched service from the first public land mobile network while detecting the second public land mobile network.

6. The method according to claim 1, wherein the method further comprises: after the defined time period expires, removing the first value, the at least one type of service, and the defined time period from the list.

7. A user equipment for managing valid services from a public land mobile network, the user equipment comprises: a receiver configured to detect a first public land mobile network associated with at least one first parameter, register with the first public land mobile network, and detect an interruption of a radio resource connection with the first public land mobile network, the interruption including that the first public land mobile network does not reject the registration request of the user equipment but stops providing at least one type of service to the user equipment, the interruption causing loss of access to the at least one type of service from the first public land mobile network; and At least one processor configured to add the at least one first parameter, the at least one type of service, and the defined time period to a list during the defined time period upon detecting the interruption. Wherein the receiver is further configured to detect, within the defined time period, a second public land mobile network associated with at least one second parameter, the second public land mobile network providing access to the at least one type of service, the at least one second parameter being different from the at least one first parameter.

8. The user equipment according to claim 7, Wherein, The at least one first parameter includes at least one of an identification code of the first public land mobile network, a location area code, and a tracking area code.

9. The user equipment according to claim 7, Wherein, The interruption of the radio resource connection further includes: a failure in sending a registration request of the user equipment, or no response being received from the first public land mobile network to the registration request of the user equipment.

10. The user equipment according to claim 7, Wherein, The at least one type of service is a packet switched service, and The receiver is further configured to: receive a circuit switched service from the first public land mobile network during the detection of the second public land mobile network.

11. The user equipment according to claim 7, Wherein, The at least one type of service is a circuit switched service, and The receiver is further configured to: receive a packet switched service from the first public land mobile network during the detection of the second public land mobile network.

12. The user equipment according to claim 7, Wherein, The at least one processor is further configured to: Remove the at least one first parameter, the at least one type of service, and the defined time period from the list in response to determining that the defined time period has expired.

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