A method and system for performing an optimal non-terrestrial network selection by a user equipment

Abstract

The present subject matter refers to a method (600) for performing Non-Terrestrial Network (NTN) selection by a User Equipment (UE) (202). The method comprises determining (602) an unavailability of network services on a Terrestrial Network (TN). In response to determining the unavailability of the network services on the TN, the method comprises identifying (604) a plurality of NTN Public Land Mobile Networks (PLMNs) at a location of the UE (202). The method further comprises ranking (606) each of the identified plurality of NTN PLMNs based on one or more predefined parameters. Moreover, the method comprises selecting (608) an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking.

Description

A METHOD AND SYSTEM FOR PERFORMING AN OPTIMAL NON-TERRESTRIAL NETWORK SELECTION BY A USER EQUIPMENT

[0001] The present invention generally relates to wireless communications, and more specifically relates to a method and a system for performing an optimal non-terrestrial network selection by a user equipment.

[0002] Non-Terrestrial Networks (NTNs) are communication networks that connect a user equipment (UE) on land, at sea, and in the sky. For mobile communication, NTN services utilize satellite-based infrastructure to extend coverage beyond traditional terrestrial networks, allowing devices to maintain connectivity in areas where ground-based networks are unavailable, such as remote locations, at sea, or in the air. However, communication over an NTN is a costly affair for the UE as the process involves scanning, searching, and finding faint NTN radio signals. The UE must then transmit over the identified faint NTN radio signals, often using maximum transmission power to reach the satellite. Furthermore, users in search of these NTN radio signals are typically in a Terrestrial Network (TN) coverage dead zone with possibly limited access to electricity. Thus, optimizing power consumption on the device is of paramount importance.

[0003] Furthermore, such situations get more complex for Dual SIM devices. For example, when one SIM (SIM1) of the dual SIM device has available TN service while the other SIM (SIM2) is out of service (OOS). In such a case, conventional techniques still require the UE to continue scanning for NTN Public Land Mobile Networks (PLMNs) on the SIM2. This occurs even when the TN service is available on the SIM1. Such scanning is power intensive and leads to unnecessary NTN load, as the device can use more reliable TN service on the SIM1.

[0004] A similar issue arises when both the SIMs are OOS, but wireless connectivity (such as via Wi-Fi or hotspot) is available. In such a scenario, scanning for NTN PLMNs is unnecessary. Therefore, methods are needed to optimize both the scanning and the selection process for NTNs. Selecting the best available profile or SIM for NTN access is crucial. However, conventional techniques fail to provide an effective solution to overcome problems stated above.

[0005] Thus, there is a need to overcome the above-mentioned problems in wireless communications.

[0006] This summary is provided to introduce a selection of concepts in a simplified format that are further described in the detailed description of the invention. This summary is not intended to identify essential inventive concepts of the invention, nor is it intended to determine the scope of the invention.

[0007] According to one embodiment of the present disclosure, a method for performing Non-Terrestrial Network (NTN) selection by a User Equipment (UE) is disclosed. The method includes determining an unavailability of network services on a Terrestrial Network (TN). In response to determining the unavailability of the network services on the TN, the method includes identifying a plurality of NTN Public Land Mobile Networks (PLMNs) at a location of the UE. The method further includes ranking each of the identified plurality of NTN PLMNs based on one or more predefined parameters. Moreover, the method includes selecting an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking.

[0008] According to another embodiment of the present disclosure, a system to perform Non-Terrestrial Network (NTN) selection by a User Equipment (UE) is disclosed. The system includes a memory and at least one processor in communication with the memory. The at least one processor is configured to determine an unavailability of network services on a Terrestrial Network (TN). In response to determining the unavailability of the network services on the TN, the at least one processor is configured to identify a plurality of NTN Public Land Mobile Networks (PLMNs) at a location of the UE. The at least one processor is further configured to rank each of the identified plurality of NTN PLMNs based on one or more predefined parameters. Moreover, the at least one processor is configured to select an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking.

[0009] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawing. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

[0010] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0011] Figure 1 illustrates a network environment illustrating Terrestrial Network (TN) and Non-Terrestrial Network (NTN), according to state of the art;

[0012] Figure 2 illustrates a block diagram of a system to perform NTN selection by a User Equipment (UE), according to an embodiment of the present disclosure;

[0013] Figure 3 illustrates an exemplary process flow of a method for NTN selection by the UE, according to an embodiment of the present disclosure;

[0014] Figure 4 illustrates a process flow of a method for obtaining ranks of a plurality of NTN Public Land Mobile Networks (PLMNs), according to an embodiment of the present disclosure;

[0015] Figure 5 illustrates an overall process flow for NTN selection by the UE, in accordance with an embodiment of the present disclosure;

[0016] Figure 6 illustrates a flow chart of a method for performing NTN selection by the UE, according to an embodiment of the present disclosure;

[0017] Figure 7 illustrates one or more problem scenarios associated with NTN selection in a dual-SIM UE when the TN services are still available on a subscription different from the one currently in use on the UE, according to the related art;

[0018] Figure 8A-8B illustrate a first and a second solution scenario corresponding to the one or more problem scenarios of Fig. 7, according to one or more embodiments of the present disclosure;

[0019] Figure 9 illustrates one or more problem scenarios associated with NTN selection in a dual-SIM UE when the UE is out of service on both SIM slots but Wi-Fi or Voice over Wi-Fi (VoWiFi) network is available at the location of the UE, according to the related art;

[0020] Figure 10 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 9, according to one or more embodiments of the present disclosure;

[0021] Figure 11 illustrates one or more problem scenarios associated with NTN selection in a dual-SIM UE when one SIM is capable of accessing a higher-ranking NTN service and another SIM is capable of accessing a lower-ranking NTN service, according to the related art;

[0022] Figure 12 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 11, according to one or more embodiments of the present disclosure;

[0023] Figure 13 illustrates one or more problem scenarios associated with NTN selection when a dual-SIM UE supports Multi-Enabled Profiles (MEPs), according to the related art;

[0024] Figures 14A-14B illustrate a solution scenario corresponding to the one or more problem scenarios of Fig. 13, according to one or more embodiments of the present disclosure;

[0025] Figure 15 illustrates one or more problem scenarios associated with switching between 3GPP based and non-3GPP based NTN services in the UE, according to the related art;

[0026] Figure 16 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 15, according to one or more embodiments of the present disclosure;

[0027] Figure 17 illustrates one or more problem scenarios associated with the prioritization of emergency SMS when a dual-SIM UE camps on an NTN PLMN, according to the related art;

[0028] Figures 18A-18B illustrate a solution scenario corresponding to the one or more problem scenarios of Fig. 17, according to one or more embodiments of the present disclosure;

[0029] Figures 19A-19B illustrate one or more problem scenarios associated with high power drain and thermal mitigation situations for an NTN, according to the related art;

[0030] Figures 20A-20B illustrate one or more solution scenarios corresponding to one or more problem scenarios of Figs. 19A-19B, according to one or more embodiments of the present disclosure;

[0031] Figure 21 illustrates one or more problem scenarios associated with Default Data Subscription (DDS) switch between the TN and the NTN services, according to the related art; and

[0032] Figure 22 illustrates one or more solution scenarios corresponding to the one or more problem scenarios of Fig. 21, according to one or more embodiments of the present disclosure.

[0033] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0034] It should be understood at the outset that although illustrative implementations of the embodiments of the present disclosure are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0035] The term “some” as used herein is defined as “none, or one, or more than one, or all.” Accordingly, the terms “none,” “one,” “more than one,” “more than one, but not all” or “all” would all fall under the definition of “some.” The term “some embodiments” may refer to no embodiments, to one embodiment, to several embodiments, or to all embodiments. Accordingly, the term “some embodiments” is defined as meaning “no embodiment, or one embodiment, or more than one embodiment, or all embodiments.”

[0036] The terminology and structure employed herein is for describing, teaching, and illuminating some embodiments and their specific features and elements and does not limit, restrict, or reduce the spirit and scope of the claims or their equivalents.

[0037] More specifically, any terms used herein such as but not limited to “includes,” “comprises,” “has,” “consists,” and grammatical variants thereof do NOT specify an exact limitation or restriction and certainly do NOT exclude the possible addition of one or more features or elements, unless otherwise stated, and must NOT be taken to exclude the possible removal of one or more of the listed features and elements, unless otherwise stated with the limiting language “MUST comprise” or “NEEDS TO include.”

[0038] Whether or not a certain feature or element was limited to being used only once, either way, it may still be referred to as “one or more features”, “one or more elements”, “at least one feature”, or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element does NOT preclude there being none of that feature or element, unless otherwise specified by limiting language such as “there NEEDS to be one or more . . .”, or “one or more element is REQUIRED.”

[0039] Unless otherwise defined, all terms, and especially any technical and / or scientific terms, used herein may be taken to have the same meaning as commonly understood by one having ordinary skill in the art.

[0040] The present disclosure provides methods and systems for selecting a Non-Terrestrial Network (NTN) Public Land Mobile Network (PLMN) when Terrestrial Networks (TNs) and NTNs are available, NTN and Wi-Fi networks are available, multiple NTNs are available, and in case multiple subscriptions / Subscriber Identity Modules (SIMs) are present in a User Equipment (UE). The present disclosure provides methods and systems for optimally ranking and selecting the best NTN PLMN when multiple possibilities exist in order to prevent unnecessary NTN access and scanning thereby reducing power consumption. The present disclosure also prohibits the UE from camping on NTN PLMNs until necessary, this reduces power consumption of the UE and also prevents unnecessary NTN overload.

[0041] Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[0042] Figure 1 illustrates a network environment 100 illustrating TN and NTN, according to state of the art. Furthermore, the NTN, as illustrated in Fig. 1, refers to networks operating through an air / spaceborne vehicle for communication. The applications of the NTN may be divided into 3 categories, which are mentioned below:

[0043] Service continuity: The NTN may provide service continuity in areas where communication service is otherwise infeasible, such as, in rural areas, deserts, forests, oceans, etc.

[0044] Service ubiquity: The NTN may provide communication service during disasters or outages in TNs.

[0045] Service scalability: The NTN may also offload traffic from the TN.

[0046] The network environment 100 includes the TN and the NTN. The TN includes one or more PLMNs. Each PLMN includes a Mobile Switching Centre (MSC), a number of cell site antennas, or one or more Base Stations (BS). MSCs and PLMNs may communicate over a network connection which may include a physical connection or a wireless connection.

[0047] In 3GPP, the NTN may include a network such as, but is not limited to, a satellite-based cellular network, a high altitude platform station-based cellular network, or an air-to-ground-based network. In some embodiments, the NTN may also include an Unmanned Aerial Vehicle (UAV)-based cellular network.

[0048] The embodiments illustrated in Fig. 1 are exemplary, and the TN and / or NTN may include any corresponding communication network / interface, as applicable.

[0049] Figure 2 illustrates a block diagram of a system 200 to perform NTN selection by the UE, according to an embodiment of the present disclosure. The system 200 may be communicatively coupled to one or more UEs 202 or be integrated within the one or more UEs 202. In an embodiment, the system 200 may form a part of the one or more UEs 202. Examples of the UEs 202 may include, but are not limited to, a smartphone, a tablet, a laptop, a personal computing device, wearable devices, health monitoring devices, and so forth.

[0050] In an embodiment, the UE 202 may refer to a mobile device or a terminal, designed for transmitting and receiving data over a wireless network. Examples of the UE 202 may include a wide range of devices such as, but not limited to, smartphones, tablets, laptops, and Internet of Things (IoT) devices, each equipped with wireless communication capabilities. The UE 202 may be configured to establish connections, communicate with network infrastructure, and access various services, applications, and data through wireless protocols and technologies, including but not limited to cellular, Wi-Fi, and Bluetooth, in compliance with the specifications and standards governing the network.

[0051] In some embodiments, the UE 202 may be a multi-SIM terminal holding multiple subscriber identification cards (hereinafter referred to as subscriptions). In an embodiment, the UE may be a dual-SIM terminal holding two subscriptions. In an embodiment, none of the two subscriptions offer NTN services. In another embodiment, one of the two subscriptions offers NTN services. In yet another embodiment, both of the subscriptions offer NTN services.

[0052] The system 200 may include a memory 208, one or more processors 206 (hereinafter referred to as the processor 206), and one or more modules 210.

[0053] In an exemplary embodiment, the processor 206 may be operatively coupled to each of the memory 208, and the modules 210. The processor 206 may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. In one embodiment, the processor 206 may include a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or both. The processor 206 may be one or more general processors, Digital Signal Processors (DSPs), application-specific integrated circuits, Field-Programmable Gate Arrays (FPGAs), servers, networks, digital circuits, analog circuits, combinations thereof, or other now known or later developed devices for analyzing and processing data. The processor 206 may execute a software program, such as code generated manually (i.e., programmed) to perform the desired operation. The processor 206 may implement various techniques such as, but not limited to, data extraction, Artificial Intelligence (AI), Machine Learning (ML), Deep Learning (DL) and so forth to achieve the desired objective.

[0054] In an embodiment, the processor 206 may be configured to determine an absence of network services on a TN. In an embodiment, the TN may comprise a Wi-Fi network, a Wi-Fi associated network, and a 3GPP TN access. In response to determining the absence of the network services on the TN, the processor 206 may identify a plurality of NTN PLMNs at a location of the UE 202. The processor 206 may also be configured to rank each of the identified plurality of NTN PLMNs based on one or more predefined parameters. In an embodiment, the one or more predefined parameters may include, but not limited to, network capabilities, available network resources, and an associated radio cost. The network capabilities may include factors such as, but not limited to, bandwidth, latency, reliability, scalability, security, and Quality of Service (QoS). The available network resources may include various elements that can be allocated or utilized within a network. Examples of such elements may include, but not limited to, spectrum, base stations, communication channels, switches, network devices and / or other network resources. The associated radio cost may refer to economic implications of the deploying and operating the radio components to access the network. In an embodiment, the processor 206 may rank the identified plurality of NTN PLMNs based on an available power level in the UE 202. The processor 206 may select an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking such that the selection of the NTN PLMN is associated with an uninterrupted network service for the UE 202. In an embodiment, the processor 206 may also be configured to prioritize emergency messages on the selected NTN PLMN based on a predetermined priority assigned to a recipient or adjusting a back-off timer.

[0055] The processor 206 may also be configured to disable access to the identified plurality of NTN PLMNs in response to determining a presence of the network services on the TN. In an embodiment, the processor 206 may add the identified plurality of NTN PLMNs to a Forbidden PLMN (FPLMN) list in the UE 202 to disable access to the identified plurality NTN PLMN.

[0056] In some embodiments, the UE 202 may be configured with Multi-Enabled Profile (MEP) support. In an embodiment, for the UE 202 with the MEP support, the processor 206 may be configured to add a Home PLMN (HPLMN) with the NTN access to the identified plurality of NTN PLMNs. In another embodiment, for the UE 202 with the MEP support, the processor 206 may be configured to add a Visitor PLMN (VPLMN) with the NTN access to the identified plurality of NTN PLMNs. The VPLMN may be present in an Operator preferred PLMN (OPLMN) list of the UE 202 with the MEP support.

[0057] In some embodiments, the memory 208 may be communicatively coupled to the at least one processor 206. The memory 208 may be configured to store data, instructions executable by the at least one processor 206. In one embodiment, the memory 208 may communicate via a bus within the system 200. The memory 208 may include, but is not limited to, a non-transitory computer-readable storage media, such as various types of volatile and non-volatile storage media including, but not limited to, random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, magnetic tape or disk, optical media and the like. In one example, the memory 208 may include a cache or random-access memory for the processor 206. In alternative examples, the memory 208 is separate from the processor 206, such as a cache memory of a processor, the system memory, or other memory. The memory 208 may be an external storage device or database for storing data. The memory 208 may be operable to store instructions executable by the processor 206. The functions, acts or tasks illustrated in the figures or described may be performed by the programmed processor 206 for executing the instructions stored in the memory 208. The functions, acts or tasks are independent of the particular type of instructions set, storage media, processor or processing strategy and may be performed by software, hardware, integrated circuits, firmware, micro-code and the like, operating alone or in combination. Likewise, processing strategies may include multiprocessing, multitasking, parallel processing, and the like. The memory 208 may further include a database to store the data. Further, the memory 208 may include an operating system for performing one or more tasks of the system 200, as performed by a generic operating system in the communications domain.

[0058] The modules 210, amongst other things, include routines, programs, objects, components, data structures, etc., which perform particular tasks or implement data types. The modules 210 may also be implemented as, signal processor(s), state machine(s), logic circuitries, and / or any other device or component that manipulates signals based on operational instructions.

[0059] Further, the modules 210 can be implemented in hardware, instructions executed by a processing unit, or by a combination thereof. The processing unit can comprise a computer, the processor 206, a state machine, a logic array, or any other suitable devices capable of processing instructions. The processing unit can be a general-purpose processor which executes instructions to cause the general-purpose processor to perform the required tasks, or the processing unit can be dedicated to performing the required functions. In another embodiment of the present disclosure, the modules 210 may be machine-readable instructions (software) which, when executed by a processor / processing unit, perform any of the described functionalities. Further, the data serves, amongst other things, as a repository for storing data processed, received, and generated by one or more of the modules.

[0060] In one example, the modules 210 may include a determination module 212, an identification module 214, an NTN ranking module 216, an NTN selection module 218, an MEP NTN prioritization module 220, an NTN FPLMN handler module 222, an emergency SMS prioritization module 224, and an NTN thermal handling module 226. The determination module 212, the identification module 214, the NTN ranking module 216, the NTN selection module 218, the MEP NTN prioritization module 220, the NTN FPLMN handler module 222, the emergency SMS prioritization module 224, and the NTN thermal handling module 226 may be in communication with each other. In an embodiment, the modules 210 may interface with one of more of a CP SUB 1 228, a CP SUB 2 230, an MEP module 232, and an application processor (AP) 234. In an embodiment, the CP SUB 1 and the CP SUB 2 are control plane (CP) protocol stack for the two subscriptions (SIM1 and SIM2 respectively) of the dual-SIM user equipment 202. In an embodiment, the MEP module 232 is an electronic-SIM chip used by the user equipment 202 to access services based on the two subscriptions.

[0061] The determination module 212 may be configured to determine the absence of the network services on the TN. In an embodiment, the determination module 212 may be configured to determine the absence of the network services on the TN by determining whether the UE 202 is out of service on either subscription. In another embodiment, the determination module 212 may be configured to determine the absence of the network services on the TN by determining whether any Wi-Fi network or hotspot is available at the location of the UE 202. In another embodiment, the determination module 212 may be configured to determine the absence of the network services on a TN by determining whether any 3GPP TN access is available at the location of the UE 202. The determination module 212 may also be configured to determine whether the UE 202 is in service in either subscription present on the UE 202. The determination module 212 may further be configured to determine whether the subscriptions on the UE 202 are NTN capable. The determination module 212 may also be configured to decide whether searching for the NTN PLMNs available at the location of the UE 202 should be a priority in a given scenario. In an embodiment, the determination module 212 decides that searching for the NTN PLMNs available at the location of the UE 202 should be the priority based on the absence of the network services on the TN.

[0062] The identification module 214 may be configured to identify the plurality of NTN PLMNs at the location of the UE 202 in response to determining the absence of the network services on the TN by the determination module 212.

[0063] The NTN ranking module 216 may be configured to rank each of the identified plurality of NTN PLMNs based on the one or more predefined parameters. In an embodiment, the one or more predefined parameters may include, but not limited to, the network capabilities or services offered, the available network resources, and the associated radio cost. The services offered by the NTN PLMNs may include, but not limited to, emergency SMS support, emergency call support, SMS / MMS support, data support, content-rich services support, etc. In an embodiment, the NTN ranking module 216 is aware of the services offered by each of the NTN PLMNs either by configuration or based on previous learning history (when the UE 202 selected that NTN PLMN). In another embodiment, the NTN ranking module 216 may be configured to rank the identified plurality of NTN PLMNs based on the available power level in the UE 202. Further, the NTN ranking module 216 may be configured to indicate the NTN PLMN with the highest ranking from among the plurality of identified NTN PLMNs.

[0064] In an embodiment, the NTN selection module 218 may be configured to select an NTN PLMN among the identified plurality of NTN PLMNs with the highest ranking such that the selection of the NTN PLMN is associated with the uninterrupted network service for the UE 202. In an embodiment, the NTN selection module 218 may be implemented in the UE 202 to perform NTN selection when the multiple subscriptions offer the NTN services simultaneously. The NTN selection module 218 may be capable of selecting the most efficient NTN PLMN for a given scenario. Further, the NTN selection module 218 may be configured to interact with the AP 234 to exchange information on the availability of the NTN PLMNs at a particular global positioning system (GPS) coordinate or location at a particular time.

[0065] The MEP NTN prioritization module 220 may be configured to determine whether the UE 202 supports more than one MEP. In an embodiment, the MEP NTN prioritization module 220 may be configured to add the HPLMN with the NTN access to the identified plurality of NTN PLMNs for the UE 202 with the MEP support. In another embodiment, the MEP NTN prioritization module 220 may be configured to add the VPLMN with the NTN access to the identified plurality of NTN PLMNs. The VPLMN may be present in the OPLMN list of the UE 202 with the MEP support. Further, the MEP NTN prioritization module 220 may be configured to indicate which of the MEPs has access to the NTN services or offers the NTN services when the UE 202 holds multiple subscriptions. The MEP NTN prioritization module 220 may also be configured to suggest a profile switch to a profile that can offer the NTN services if the UE 202 has detected an NTN PLMN that belongs to a different subscription than the one currently in use.

[0066] The NTN FPLMN handler module 222 may be configured to disable access to the identified plurality of NTN PLMNs in response to determining the presence of network services on the TN. In an embodiment, the TN may comprise the Wi-Fi network, the Wi-Fi associated network, and the 3GPP TN access. The NTN FPLMN handler module 222 may also be configured to add the identified plurality of NTN PLMNs to the FPLMN list in the UE 202 to disable access to the identified plurality of NTN PLMNs in response to determining the presence of network services on the TN. In an embodiment, to disable access to the identified plurality of NTN PLMNs in response to determining the presence of network services on the TN, the NTN FPLMN handler module 222 may be configured to prevent the NTN PLMNs from being scanned. The NTN FPLMN handler module 222 may also be configured to disable access to the identified plurality of NTN PLMNs in response to determining the presence of network services on another NTN service provider. In case the identification module 214 identifies multiple NTN PLMNs available at the location of the UE 202, the NTN FPLMN handler module 222 may be configured to store the NTN FPLMNs with lower ranks in the FPLMN list in order to prevent the UE 202 from accessing an NTN PLMN with a lower rank.

[0067] The emergency SMS prioritization module 224 may be configured to prioritize emergency messages on the selected NTN PLMN based on a predetermined priority assigned to a recipient or adjusting a back-off timer. The emergency SMS prioritization module 224 helps in sending out the emergency messages (or, SMS) on priority when an NTN link is weak.

[0068] The NTN thermal handling module 226 may be configured to optimize thermal effects arising at the UE 202 due to repeated transmissions or due to high usage of transmission power.

[0069] The details explanation of various steps being performed by the system 200 has been explained in the following description. Further, embodiments are exemplary, and the system 200 may include any additional component required to implement the desired functionality of the system 200, i.e., to perform NTN selection by the UE 202.

[0070] Figure 3 illustrates an exemplary process flow of a method 300 for the NTN PLMN selection by the UE 202, according to an embodiment of the present disclosure. The method 300 may be implemented by the system 200 depicted in Fig. 2.

[0071] The method 300 illustrated in Fig. 3 begins at operation 302, where the UE 202 may be powered ON and initialized for the NTN PLMN selection. Thereafter, at operation 304, the determination module 212 determines whether the UE 202 is in service in either subscription. In an embodiment, the determination module determines that the UE 202 is in service in either subscription based on the availability of the TN services on the subscriptions. If the UE 202 is a dual-SIM terminal, i.e. the UE 202 holds two subscriptions, the availability of the TN services on both subscriptions is checked. Upon determining that the UE 202 is in service in either subscription, the UE 202 camps on the subscription with available TN service and the process moves to operation 306. At operation 306, the NTN FPLMN handler module 222 disables search for the available NTN PLMNs until the UE 202 is no longer in service in either subscription. Further, at operation 304, if the determination module 212 determines that the UE 202 is no longer in service in either subscription, the process progresses to operation 310, where the determination module 212 determines the availability of any Wi-Fi network at the location of the UE 202. Upon determining the availability of a Wi-Fi network at the location of the UE 202, the UE 202 uses the Wi-Fi network for call and / or data services and the process moves to operation 312. At operation 312, the NTN FPLMN handler module 222 disables the search for the available NTN PLMNs. Further to the NTN FPLMN handler module 222 disabling search for the available NTN PLMNs at operation 306 and 312, the process moves to operation 308. At operation 308, the NTN FPLMN handler module 222 stores the available NTN PLMNs in the FPLMN list in the UE 202 until the determination module 212 determines the absence of TN services at the location of the UE 202.

[0072] Alternatively, at operation 310, upon determining the unavailability of any Wi-Fi network at the location of the UE 202 by the determination module 212, the process moves to operation 314. At operation 314, the MEP NTN prioritization module 220 determines whether the UE 202 supports more than one MEP. In case the UE 202 supports more than one MEP, the process moves to operation 316. At operation 316, the MEP NTN prioritization module 220 obtains candidate NTN(s) and the process moves to operation 320. At operation 320, the NTN ranking module 216 ranks the available NTN PLMNs and the process moves to operation 322. In an embodiment, the identification module 214 identifies the available NTN PLMNs in response to determining the absence of network services on TN. At operation 322, the NTN selection module 218 selects the NTN PLMN with the highest rank. Finally, the process moves to operation 324 and the emergency SMS prioritization module 224 and the NTN thermal handling module 226 apply the emergency SMS prioritization policy and thermal policy respectively. The emergency SMS prioritization policy and the thermal policy are explained in detail with reference to Figs. 17-18B and Figs. 19A-20B respectively.

[0073] Alternatively, upon determining at operation 314 that the UE 202 does not support more than one MEP, the process moves to operation 318. At operation 318, the determination module 212 determines whether the subscriptions on the UE 202 are NTN-capable. In case both the subscriptions on the UE 202, in case of the dual-SIM UE 202, are NTN-capable, the process moves to operation 320 explained above. Alternatively, if the determination module 212 determines that only one of the subscriptions on the UE 202 is NTN-capable, the process moves to operation 326. At operation 326, the UE 202 switches to the NTN-capable subscription. Thereafter, the process moves to operation 324 explained above.

[0074] The above process is an exemplary process and the steps thereof as shown in Fig. 3 may occur in variations to the sequence in accordance with various embodiments. The process illustrated in Fig. 3 may further include additional steps (not included), in accordance with various embodiments.

[0075] Figure 4 illustrates a process flow of a method 400 for obtaining ranks of the plurality of NTN PLMNs, according to an embodiment of the present disclosure.

[0076] The method 400 starts at operation 402, where either the MEP NTN prioritization module 220 obtains candidate NTN(s) or the determination module 212 determines NTN capability on both the subscriptions on UE 202, in case of the dual-SIM UE. Then, the process moves to operation 404, where the NTN ranking module 216 determines the power level available in the UE 202. In case the NTN ranking module 216 determines a limited power level in the UE 202, the process moves to operation 406. At operation 406, the NTN ranking module 216 checks whether the NTN PLMNs available at the location of the UE 202 and identified by the identification module 214 have emergency SMS support. For the NTN PLMNs having emergency SMS support, the NTN ranking module 216 adds a predefined value (for example, a value ‘A’) to the rank of those NTN PLMNs. In an embodiment, the value ‘A’ is a predefined numerical value. In an embodiment, if the NTN ranking module 216 determines that the identified NTN PLMNs available at the location of the UE 202 do not have emergency SMS support, the rank of the NTN PLMNs remains unchanged. In an exemplary scenario, the identification module 214 determines two NTN PLMNs (hereinafter, NTN1 and NTN2) at the location of the UE 202. In this example, the initial ranks of NTN1 and NTN2 are R1 and R2 respectively and the value ‘A’ has a numerical value 5. At operation 406, the NTN ranking module 216 determines that NTN1 has emergency SMS support and NTN2 does not have emergency SMS support. Accordingly, the NTN ranking module 216 adds a value ‘A’ (i.e. numerical value 5) to the initial rank R1 of the NTN1, and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 406 become R1+5 and R2 respectively.

[0077] In an exemplary scenario where the UE is operating on battery power, the ranking process is dynamically adjusted based on remaining battery level. When the battery level drops to a first threshold level, the NTN ranking module 216 modifies the ranking process to prioritize power efficiency over service capabilities. In this case, the ranking weight for NTN PLMNs requiring lowest transmission power is increased, while content-rich services are given an additional penalty. When the battery level falls below a second threshold level which is lower than the first threshold level, the ranking module 216 further adjusts the process to prioritize only emergency services, significantly increasing the ranking weight for emergency SMS and call support, while excluding NTN PLMNs that only provide non-essential services from the ranking list.

[0078] Thereafter, the process moves to operation 408, where the NTN ranking module 216 checks whether the identified NTN PLMNs available at the location of the UE 202 have emergency call support. For the NTN PLMNs having emergency call support, the NTN ranking module 216 adds the value ‘A’ to the rank obtained at operation 406 corresponding to the NTN PLMNs. In an embodiment, the value added to the rank at operation 406 is different from the value added to the rank at operation 408. In an embodiment, if the NTN ranking module 216 determines that the identified NTN PLMNs available at the location of the UE 202 do not have emergency call support, the rank of the NTN PLMNs remains unchanged. In the above-explained exemplary scenario, at operation 408, the NTN ranking module 216 determines that NTN1 has emergency call support and NTN2 does not have emergency call support. Accordingly, the NTN selection module 216 adds 5 to the rank R1+5 of the NTN1 and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 408 become R1+10 and R2 respectively.

[0079] Further, the process moves to operation 410, where the NTN ranking module 216 determines which one of the identified NTN PLMNs available at the location of the UE 202 has the strongest Reference Signal Received Power (RSRP). For the NTN PLMNs having the strongest RSRP, the NTN ranking module 216 adds the value ‘A’ to its rank obtained at operation 408. In an embodiment, the ranks of the remaining NTN PLMNs remain unchanged. In an embodiment, the values added to the rank at operation 406, operation 408, and operation 410 are different from each other. In the above-explained exemplary scenario, at operation 410, the NTN ranking module 216 determines that NTN1 has the strongest RSRP among NTN1 and NTN2. Accordingly, the NTN selection module 216 adds 5 to the rank R1+10 of the NTN1 and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 410 become R1+15 and R2 respectively.

[0080] Further, the process moves to operation 412, where the NTN ranking module 216 determines which one of the identified NTN PLMNs available at the location of the UE 202 requires the lowest transmission power. For the NTN PLMNs requiring the lowest transmission power, the NTN ranking module 216 adds the value ‘A’ to its rank obtained at operation 410. In an embodiment, the ranks of the remaining NTN PLMNs remain unchanged. In an embodiment, the values added to the rank at operation 406-412 are different from each other. In the above-explained exemplary scenario, at operation 412, the NTN ranking module 216 determines that NTN1 requires the lowest transmission power among NTN1 and NTN2. Accordingly, the NTN selection module 216 adds 5 to the rank R1+15 of the NTN1 and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 412 become R1+20 and R2 respectively.

[0081] Thereafter, the process moves to operation 414, where the NTN ranking module 216 determines whether the identified NTN PLMNs available at the location of the UE 202 have SMS / MMS support. For the NTN PLMNs having SMS / MMS support, the NTN ranking module 216 adds the value ‘B’ to the ranks obtained at operation 412 for those NTN PLMNs. In an embodiment, the ranks of the NTN PLMNs not having SMS / MMS support remain unchanged. In an embodiment, the value ‘B’ is a numerical value. In an embodiment, the value ‘B’ is the same as the value ‘A’. In the above-explained exemplary scenario, at operation 414, the NTN ranking module 216 determines that NTN1 has the SMS / MMS support and NTN2 does not have the SMS / MMS support. In this example, the value of ‘B’ is numerical value 2. Accordingly, the NTN selection module 216 adds 2 to the rank R1+20 of the NTN1 and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 414 become R1+22 and R2 respectively.

[0082] Thereafter, the process moves to operation 416, where the NTN ranking module 216 determines whether the identified NTN PLMNs available at the location of the UE 202 have data support. For the NTN PLMNs having data support, the NTN ranking module 216 subtracts the value ‘C’ from the ranks obtained at operation 414 for those NTN PLMNs. In an embodiment, the ranks of the NTN PLMNs not having data support remain unchanged. In an embodiment, the value ‘C’ is a numerical value. In an embodiment, the value ‘C’ is the same as at least one of the values ‘A’ and ‘B’. In the above-explained exemplary scenario, at operation 416, the NTN ranking module 216 determines that NTN1 has the data support and NTN2 does not have the data support. In this example, the value of ‘C’ is numerical value 4. Accordingly, the NTN selection module 216 subtracts 4 from the rank R1+22 of the NTN1, and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 416 become R1+18 and R2 respectively.

[0083] Thereafter, the process moves to operation 418, where the NTN ranking module 216 determines whether the identified NTN PLMNs available at the location of the UE 202 have content-rich services support. For the NTN PLMNs having content-rich services support, the NTN ranking module 216 subtracts the value ‘C’ from the ranks obtained at operation 416 for those NTN PLMNs. In an embodiment, the ranks of the NTN PLMNs not having content-rich services support remain unchanged. In the above-explained exemplary scenario, at operation 418, the NTN ranking module 216 determines that NTN1 has content-rich services support and NTN2 does not have content-rich services support. Accordingly, the NTN selection module 216 subtracts 4 from the rank R1+18 of the NTN1, and the rank of NTN2 remains unchanged. The updated ranks of NTN1 and NTN2 after operation 418 become R1+14 and R2 respectively.

[0084] Finally, at operation 420, the NTN ranking module 216 outputs the ranks of the identified NTN PLMNs at the location of the UE 202 in the scenario of the UE 202 having a limited power level. In the above-explained exemplary scenario, the NTN ranking module 216 outputs the final ranks of NTN1 and NTN2 as R1+14 and R2 respectively.

[0085] Alternatively, if the NTN ranking module 216 determines that the power level of the UE 202 is not limited, the process moves to operation 422. The operations 422-436 are similar to the operations 406-418 explained with reference to the scenario with the UE 202 having limited power level in Fig. 4 and a description of these operations has been omitted for the sake of brevity.

[0086] In the scenario of the UE 202 having limited power level, the features such as having data support and content-rich services support are not necessary. Accordingly, the NTN ranking module 216 imposes penalties on the ranks of the NTN PLMNs having said features. In an embodiment, the NTN ranking module 216 imposes a penalty by subtracting a value from the ranks of the NTN PLMNs.

[0087] In the scenario of the UE 202 not having a limited power level, the features having the strongest RSRP and lowest required transmission power do not have a weight. Accordingly, the ranks of the NTN PLMNs having said features remain unchanged.

[0088] The above process is an exemplary process and the steps thereof as shown in Fig. 4 may occur in variations to the sequence in accordance with various embodiments. The process illustrated in Fig. 4 may further include additional steps (not included), in accordance with various embodiments.

[0089] Figure 5 illustrates an overall process flow for NTN selection by the UE 202, in accordance with an embodiment of the present disclosure.

[0090] In an embodiment, the process of NTN selection includes two stages ? (1) an NTN prioritization decision stage, and (2) an NTN ranking stage. During the NTN prioritization decision stage, the determination module 212 decides whether searching for the NTN PLMNs available at the location of the UE 202 should be the priority in each scenario. In an embodiment, the determination module 212 decides that searching for the NTN PLMNs available at the location of the UE 202 should be the priority based on the absence of network services on the TN.

[0091] Before the NTN selection, the determination module 212 may be configured to check whether the UE 202 is completely out of service on either subscription with no Wi-Fi network available. This is a pre-requisite before selecting an NTN PLMN. In order to prevent the UE 202 from accessing the NTN PLMN when service is available on either subscription or Wi-Fi, the NTN FPLMN handler module 222 stores the NTN PLMNs available at the location of the UE 202 in the FPLMN list in the UE 202.

[0092] Once the determination module 212 decides to search for the NTN PLMNs available at the location of the UE 202, the process moves to the NTN ranking stage, where the NTN ranking module 216 provides input on which of the available NTN PLMNs has the highest rank. The NTN ranking module 216 may be configured to obtain the ranks of the NTN PLMNs available at the location of the UE 202 in accordance with the process illustrated in Fig. 4.

[0093] In an embodiment, the MEP NTN prioritization module 220 may also be configured to suggest the profile switch to the profile that can offer the NTN services if the identification module 214 has detected an NTN PLMN that belongs to a different subscription profile than the one currently in use.

[0094] In an embodiment, when multiple NTN PLMNs are available at the location of the UE 202, the NTN selection module passes the NTN PLMNs to the NTN ranking module 216 in order to make a decision on which one of the available NTN PLMNs to select in accordance with the process illustrated in Fig. 3. In another embodiment, the NTN FPLMN handler module 222 stores the NTN PLMNs with lower ranks in the FPLMN list in order to prevent the UE 202 from accessing an NTN PLMN with a lower rank.

[0095] Once the NTN selection module 218 selects the NTN PLMN, the Emergency SMS prioritization module 224 and the NTN thermal handling module 226 apply the emergency SMS prioritization policy and the thermal policy tailored for the selected NTN PLMN respectively.

[0096] Figure 6 illustrates a flow chart of method 600 for performing NTN selection by the UE 202, according to an embodiment of the present disclosure.

[0097] At operation 602, the method 600 may include determining the absence of network services on the TN. In an embodiment, the TN comprises the Wi-Fi network, the Wi-Fi associated network, and the 3GPP TN access.

[0098] At operation 604, the method 600 may include identifying the plurality of NTN PLMNs at the location of the UE 202 in response to determining the absence of the network services on the TN.

[0099] At operation 606, the method 600 may include ranking each of the identified plurality of NTN PLMNs based on the one or more predefined parameters. The one or more predefined parameters may include, but not limited to, the network capabilities, the available network resources, and the associated radio cost. In an embodiment, method 600 may include ranking the identified plurality of NTN PLMNs based on the available power level in the UE 202.

[0100] At operation 608, the method 600 may include selecting the NTN PLMN among the identified plurality of NTN PLMNs with the highest ranking such that the selection of the NTN PLMN is associated with the uninterrupted network service for the UE 202.

[0101] Embodiments are exemplary in nature and the steps of the method 600 as shown in Fig. 6 may occur in variations to the sequence in accordance with various embodiments.

[0102] The disclosed method has several advantages, but are not limited to, some of which are listed below.

[0103] The present disclosure provides a solution for the UE 202 to optimally select the best available NTN PLMN in a single / dual SIM scenario. Specifically, the present disclosure optimizes the selection of an NTN PLMN where there are multiple options available to the UE 202 thereby enriching user experience, reducing power consumption at the UE, and avoiding NTN overload. The present disclosure also optimizes NTN scanning in order to prevent unnecessary power consumption at the UE 202. Thus, the present disclosure provides an improved UE performance and user experience whilst providing the best NTN service available, when required. Moreover, the present disclosure provides prioritization of emergency SMS and thus a higher success rate on the UEs. The present disclosure also prevents the UE from camping on NTN PLMNs until necessary.

[0104] Figure 7 illustrates one or more problem scenarios associated with NTN selection in the dual-SIM UE when the TN services are available on a subscription different from the one currently in use on the UE 202, according to the related art.

[0105] The network environment illustrated in Fig. 7 may include the dual-SIM UE 202, where only one of the subscriptions or the SIM1 is capable of accessing NTN services. In an exemplary scenario, the UE 202 goes out of service on the SIM1 having the NTN capability however the TN services are still available on the other subscription (i.e., on the SIM2). According to the related art, as the SIM1 has the NTN capability, the UE 202 camps on the NTN service and enables NTN_MODE as soon as it goes out of service on the SIM1 even though the TN services are available on the SIM2, as shown in block 702. Thus, the UE 202 consumes more power, and the NTN is also unnecessarily overloaded, as shown in block 704.

[0106] Figure 8A-8B illustrate a first and a second solution scenario corresponding to the one or more problem scenarios of Fig. 7, according to one or more embodiments of the present disclosure.

[0107] In the first solution scenario of Fig. 8A, the UE 202 may be configured to select an NTN PLMN only when the UE 202 is out of service on both subscriptions (i.e., on both the SIM1 and the SIM2). Particularly, at operation 802, the NTN FPLMN handler module 222 may be configured to hold all the NTN PLMNs available at the location of the UE 202 in the FPLMN list until the UE 202 goes out of service on both subscriptions. At operation 804, the determination module 212 checks whether the UE 202 is out of service on both subscriptions. If the determination module 212 determines that the TN service is available on SIM2, the UE 202 camps on SIM2 and the NTN FPLMN handler module 222 adds the available NTN PLMNs in the FPLMN list at operation 806. Thereafter, at operation 808, the UE 202 turns off the NTN_MODE.

[0108] Alternatively, at operation 804, if the determination module 212 determines that the UE 202 is out of service on both subscriptions, the NTN selection module 218 selects the NTN PLMN having the highest rank from the FPLMN list at operation 810. Thereafter, at operation 812, the UE 202 camps on the selected NTN PLMN via the NTN capable SIM1 and the UE 202 goes to NTN_MODE. Thus, by preventing the UE 202 from accessing the NTN PLMNs until the UE 202 is out of service on both subscriptions, the present disclosure reduces power consumption at the UE 202 and also avoids overloading the NTN.

[0109] In the second solution scenario of Fig. 8B, the steps 814-820 are similar to the steps 802-808 explained with reference to Fig. 8A and a description of these steps has been omitted for the sake of brevity. Further, while the UE 202 camps on SIM2 with the available TN services, if the determination module 212 determines, at operation 822, that the TN services are disrupted on SIM2, i.e. call / SMS failure at SIM2, the NTN selection module 218 selects the NTN PLMN having the highest rank from the FPLMN list at operation 824. Thereafter, at operation 826, the UE 202 camps on the selected NTN PLMN via the NTN-capable SIM1 and the UE 202 goes to NTN_MODE. Thus, the present disclosure enhances user experience when the UE 202 experiences service disruption in the TN services.

[0110] Figure 9 illustrates one or more problem scenarios associated with NTN selection in the dual-SIM UE when the UE 202 is out of service on both subscriptions (SIM1 and SIM2) but Wi-Fi or Voice over Wi-Fi (VoWiFi) network is available at the location of the UE 202, according to the related art.

[0111] The network environment illustrated in Fig. 8 may include the dual-SIM UE 202 in which both subscriptions are NTN-capable however the UE 202 is out of service on both subscriptions. The network environment of Fig. 8 also includes the Wi-Fi / VoWi-Fi network available at the location of the UE 202. According to the related art, the UE 202 searches for and camps on the available NTN and enables NTN_MODE as soon as it goes out of service on SIM1 and SIM2 even though the Wi-Fi / VoWi-Fi network is available at the location of the UE 202, as shown in block 902. Thus, the UE 202 consumes more power, and the NTN network is also unnecessarily overloaded, as shown in block 904. This is a very common scenario, particularly for UEs 202 in Airplane mode.

[0112] Figure 10 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 9, according to one or more embodiments of the present disclosure.

[0113] In Fig. 10, at operation 1002, when the UE 202 is out of service on both SIM1 and SIM2, the determination module 212 checks whether the Wi-Fi / VoWi-Fi network is available at the location of the UE 202. If the determination module 212 determines that the Wi-Fi / VoWi-Fi network is not available, the NTN selection module 218 selects the NTN PLMN having the highest rank from the FPLMN list at operation 1004. Thereafter, at operation 1006, the UE 202 camps on the selected NTN PLMN via any of the NTN-capable subscriptions and the UE 202 goes to NTN_MODE.

[0114] Alternatively, if the determination module 212 determines that the Wi-Fi / VoWi-Fi network is available, the UE 202 may be configured to use the available Wi-Fi / VoWi-Fi network for call / SMS services at operation 1008. Thereafter, at operation 1010, the UE 202 turns off the NTN_MODE. Thus, by preventing the UE 202 from accessing the NTN PLMNs when the Wi-Fi / VoWi-Fi network is available even when the UE 202 is out of service on both subscriptions, the present disclosure reduces power consumption by the UE 202 and also avoids overloading of the NTN network.

[0115] Figure 11 illustrates one or more problem scenarios associated with NTN selection in the dual-SIM UE when one of the subscriptions is capable of accessing a higher-ranking NTN and the other one is capable of accessing a lower-ranking NTN, according to the related art.

[0116] The network environment illustrated in Fig. 11 may include the dual-SIM UE 202 in which both subscriptions are NTN-capable where SIM1 is capable of accessing the higher-ranking NTN where, for example, both call and SMS services are allowed, and SIM2 is capable of accessing the lower-ranking NTN where, for example, only SMS services are allowed. According to the related art, the UE 202 camps on the NTN via both SIM1 and SIM2. Thus, in an exemplary situation, when the UE 202 camps on the NTN through SIM2 and tries to make a call, even though the NTN available on SIM2 does not allow call services, the UE 202 stays camped on the NTN through SIM2. Thus, the UE 202 consumes more power, and the NTN network is also unnecessarily overloaded, as shown in block 1102.

[0117] Figure 12 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 11, according to one or more embodiments of the present disclosure.

[0118] In Fig. 12, at operation 1202, the NTN FPLMN handler module 222 may be configured to keep all the NTN PLMNs available at the location of the UE 202 in the FPLMN list until the UE 202 goes out of service on both subscriptions. When the UE 202 goes out of service on both subscriptions, the NTN ranking module 218 prioritizes the available NTN PLMNs based on the obtained ranks, as shown in operation 1204. If the rank obtained for SIM1 is higher than SIM2, then SIM1 has higher subscription of the NTN services and SIM2 has lower subscription of the NTN services. Similarly, if the rank obtained for SIM2 is higher than SIM1, then SIM2 has higher subscription of the NTN services and SIM1 has lower subscription of the NTN services.

[0119] The NTN ranking module 218 decides whether the subscription has higher or lower subscription of the NTN services based on the ranks or weights of the NTN services. In an embodiment, the rank or weight of certain factors may increase or decrease based on the state (e.g., battery level) of the UE 202. In an exemplary scenario, if the UE 202 is in a low battery situation (e.g., battery < 15%), the NTN PLMN requiring

[0120] higher transmission power and providing non-essential services (e.g., internet connectivity, etc) is given lesser priority and the NTN PLMN offering only emergency services with lower cost, transmission power and better availability is given more priority.

[0121] In another embodiment, the rank or weight of certain factors may increase or decrease based on the service requirement of the UE 202. In an exemplary scenario, if the UE 202, which does not have limited power, is trying to access the NTN PLMN, the NTN ranking module 216 may not assign significant weight to factors like transmission power, radio signal quality, etc. In such a case, the NTN ranking module 216 may give the higher rank to the more feature-rich NTN PLMN.

[0122] Referring to Fig. 12, if the NTN ranking module 216 determines that SIM1 has higher-subscription NTN than SIM2, the NTN selection module 218 selects SIM1 NTN at operation 1206. Thereafter, at operation 1208, the UE 202 switches Default Data Subscription (DDS) to SIM1 on which the NTN is acquired.

[0123] Alternatively, if the NTN ranking module 216 determines that SIM2 has higher-subscription NTN than SIM1, the NTN selection module 218 selects SIM2 NTN at operation 1210. Thereafter, at operation 1212, the UE 202 switches DDS to SIM2 on which the NTN is acquired. Thus, by enabling the UE 202 to camp on the available NTN, the present disclosure improves user experience.

[0124] Figure 13 illustrates one or more problem scenarios associated with NTN selection when the dual-SIM UE supports MEPs, according to the related art.

[0125] Referring to Fig. 13, the network environment may include the UE 202 that supports MEPs and has two subscriptions ? a physical SIM (pSIM) and an electronic SIM (eSIM). The UE 202 visits a region where the NTN services are available only based on roaming partnerships. Further, the TN services are not available on any of the subscriptions in the roaming area, thus, the UE 202 is out of service on both subscriptions. In the scenario of Fig. 13, the subscriptions of the UE 202 do not have any NTN service or a roaming partnership for the NTN services on the VPLMN. In such cases, the UE 202 remains out of service even though it can acquire service on any other NTN subscribed SIM profile, as shown in block 1302.

[0126] Figures 14A-14B illustrate a solution scenario corresponding to the one or more problem scenarios of Fig. 13, according to one or more embodiments of the present disclosure.

[0127] Referring to Fig. 14A, at operation 1402, the MEP NTN prioritization module 220 searched for all the supported SIM profiles by the UE 202. The supported SIM profiles may be activated or non-activated. At operation 1404, the MEP NTN prioritization module 220 stores the OPLMN list configured for each of the supported SIM profiles in a local database (DB). At operation 1406, the UE goes out of the TN service in a roaming area for one of the supported SIM profiles (e.g. SIM1). In such a scenario, the MEP NTN prioritization module 220 searches the OPLMN list for SIM1 and determines that no TN service is available. In an embodiment, the MEP NTN prioritization module 220 may determine that no service is available because the NTN service may not be available, or the SIM profile may not be NTN capable. At operation 1408, MEP NTN prioritization module 220 checks whether any NTN PLMN is available in any of the OPLMN list stored for the SIM profiles in the local DB. In an embodiment, the MEP NTN prioritization module 220 queries the DB to check availability of the NTN PLMN in any of the SIM profiles and receives a response from the DB. If the MEP NTN prioritization module 220 finds an available NTN PLMN, the process moves to operation 1410, where the UE 202 loads the SIM profile for which the NTN PLMN is found in the OPLMN list. Thereafter, at operation 1412, the UE 202 turns on the NTN_MODE and disables all other SIM profiles to save battery. In an embodiment, if the MEP NTN prioritization module 220 finds multiple SIM profiles with available NTN PLMNs in the OPLMN list, the UE 202 prompts a user to choose a SIM profile based on a preference of the user and applicable charges.

[0128] Alternatively, if the MEP NTN prioritization module 220 does not find any available NTN PLMN, the process moves to operation 1414, where the UE 202 loads every SIM profile present in the UE 202 for finding a PLMN that can serve the UE. If the MEP NTN prioritization module 220 determines that none of the SIM profiles has the NTN capability for serving the PLMN, the UE goes out of service at operation 1416. In an embodiment, the network does not add the NTN PLMN to the OPLMN list. If no PLMN is found in the OPLMN list, then all the SIM profiles are loaded sequentially, and NTN acquisition is attempted again. Alternatively, if the MEP NTN prioritization module 220 determines even one SIM profile that has the NTN capability for serving the PLMN, the process moves to operation 1410 explained above.

[0129] Fig. 14B shows the local DB storing the OPLMN list for each of the SIM profiles. Referring to Fig. 14B, a SIM profile 1 is configured with a PLMN1, a SIM profile 2 is also configured with the PLMN1, and a SIM profile 3 is configured with a PLMN2 and an NTN-capable PLMN3. Referring to Fig. 14B, the MEP NTN prioritization module 220 loads the SIM profile 3 for the NTN services in the UE 202.

[0130] Figure 15 illustrates one or more problem scenarios associated with switching between the 3GPP based and the non-3GPP based NTN services in the UE 202, according to the related art.

[0131] Referring to Fig. 15, at the location of the UE 202, both the 3GPP and non-3GPP NTN services are available, and the UE 202 also has a subscription for both the 3GPP and non-3GPP NTN services. Certain telecom operators may deploy the 3GPP based NTN services in some regions and the non-3GPP based NTN services in other regions. Further, charging policy for both services may differ based on the region. Additionally, service capabilities (such as throughput, latency, voice and emergency capabilities, etc.) may also differ for the 3GPP and non-3GPP NTN services. According to the related art, when the UE 202 goes out of service, the UE 202 tries to camp on both the 3GPP and non-3GPP NTN services. This results in high power consumption for the UE 202, as shown in block 1502. The steps for the selection of subscription to camp on NTN_MODE are discussed with reference to Figures 8A-B and 12 and have not been explained again for the sake of brevity.

[0132] Figure 16 illustrates a solution scenario corresponding to the one or more problem scenarios of Fig. 15, according to one or more embodiments of the present disclosure.

[0133] Referring to Fig. 16, when the UE is out of service on both the subscriptions and has to go to NTN_MODE and camp on the NTN service, the NTN ranking module 216 obtains ranks for both the 3GPP and non-3GPP NTN services available at the location of the UE 202 and decides which one of the 3GPP and non-3GPP NTN services is better at operation 1602. In an embodiment, the NTN ranking module 216 takes into consideration one or more parameters such as available operators in the specific region for each type of service and user preference, charging policy (lesser priced service is given priority), user requirement for current service acquisition (e.g., if regular voice / data or emergency services required, then preference will be set accordingly or else preference can be set based on power situation), radio cost involved in accessing the service, availability of the service (e.g., number of hours in a day), etc. and decides which one of the NTN services is better. If the NTN ranking module 216 decides that the 3GPP NTN service is better, the UE 202 camps on the 3GPP based NTN subscription, at operation 1604. Alternatively, if the NTN ranking module 216 decides that the non-3GPP NTN service is better, the UE 202 camps on the non-3GPP based NTN subscription, at operation 1606. Thus, by enabling the UE 202 to camp on the better NTN service instead of both the 3GPP and non-3GPP NTN services, the present disclosure reduces power consumption for the UE 202.

[0134] Figure 17 illustrates one or more problem scenarios associated with the prioritization of the emergency messages when the dual-SIM UE 202 camps on the NTN PLMN, according to the related art.

[0135] Referring to Fig. 17, when the UE 202 goes out of service on both subscriptions, the NTN selection module 218 selects the NTN PLMN and the UE 202 turns on the NTN_MODE and camps on the selected NTN PLMN. According to the related art, the NTN PLMN does not support an emergency packet data network (PDN) and thus, when the UE 202 tries to send multiple messages including the emergency message (e.g. E911 SMS) on the weak NTN link, all the messages get same priority. Particularly, all the messages are sent serially as per a queue. Thus, the E911 SMS may get sent last or not at all because, by the time the E911 SMS gets out of a text buffer, the NTN signal becomes weak.

[0136] Figures 18A-18B illustrate a solution scenario corresponding to the one or more problem scenarios of Fig. 17, according to one or more embodiments of the present disclosure.

[0137] Specifically, Fig. 18A illustrates a first solution scenario where the UE 202 is out of service on both subscriptions, camped on the selected NTN PLMN which does not support the emergency PDN, and multiple messages are in the buffer waiting to be sent. At operation 1802, the UE 202 tries to send a new message. At operation 1804, the Emergency SMS prioritization module 224 may be configured to identify the message as an emergency message from the recipient number. In an embodiment, the message is an emergency message when the recipient number is an emergency number such as, but not limited to, 911. If the Emergency SMS prioritization module 224 identifies that the recipient number is not the emergency number, the message is not identified as the emergency message and the message is sent as per the queue, at operation 1806. Alternatively, if the Emergency SMS prioritization module 224 identifies that the recipient number is the emergency number, the message is identified as the emergency message and is sent to the start of the queue at operation 1808. Thereafter, at operation 1810, the emergency message is sent as per a modified queue and on priority.

[0138] Fig. 18B illustrates a second solution scenario for the one or more problem scenarios of Fig. 17. Referring to the solution of Fig. 18B, the emergency SMS prioritization module 224 may be configured to not use any back-off timers for the emergency message. Specifically, the solution includes customizing the back-off timers defined by 3GPP in the following manner for the NTN:

[0139] The emergency message (SMS1 of Fig. 18B) should have top priority so no back-off timer is applied to the emergency message.

[0140] Messages (SMS2 of Fig. 18B) with time-sensitive information (e.g. One Time Password (OTP) for banking / payment purposes or any other crucial service) use a small back-off timer value (e.g. 15 seconds).

[0141] Messages (SMS3 of Fig. 18B) sent to contacts marked as Favourites (i.e. contacts assigned the predetermined priority) in the UE 202 have slightly higher back-off timer values (e.g. 30 seconds).

[0142] All other messages (SMS4-6 of Fig. 18B) that have no assigned priority have highest back-off timer value (e.g. 120 seconds).

[0143] In an embodiment, the emergency SMS prioritization module 224 may be configured to prioritize the text messages in the queue according to the back-off timer value of the messages.

[0144] Figures 19A-19B illustrate one or more problem scenarios associated with high power drain and thermal mitigation situations for the NTN, according to the related art.

[0145] Specifically, Figs. 19A-19B illustrates a scenario where the UE 202 is out of service on both subscriptions and is camped on the NTN, as shown in block 1902. While sending any packet through the NTN, the UE 202 needs high transmission power, which increases the temperature of the UE 202. In case the UE 202 already has low battery and is camped on the NTN, the chances of thermal heating are higher. According to the related art, in the TNs, when thermal heating occurs due presence of legacy radio access technologies (RATs), the transfer of the emergency messages is successful. However, in the NTN, the legacy RATs are not available. Thus, the most crucial purpose of the NTN, i.e., of allowing the emergency messages to be sent out, would fail in case of the thermal heating.

[0146] Further, when the UE 202 communicates over the weak NTN link, it is unlikely that all of the messages sent by the UE 202 would reach the NTN even though the UE 202 sends the messages with maximum transmit power level (MTPL). In this scenario, the UE 202 faces radio link failure (RLF) due to multiple retransmission failures which in turn increases signaling and thermal impact. Further, the prolonged NTN usage results in faster thermal heating at the UE 202, as shown in block 1904. Once there is thermal heating, thermal management software present at the UE 202 prevents the emergency message from being sent, as shown in block 1906.

[0147] Figures 20A-20B illustrate one or more solution scenarios corresponding to the one or more problem scenarios of Figs. 19A-19B, according to one or more embodiments of the present disclosure.

[0148] Referring to Figs. 20A, the UE 202, which is out of service on both subscriptions and camped on the NTN, tries to send a message via the NTN link. At operation 2002, the NTN thermal handling module 226 determines that the UE 202 has hit severe thermal mitigation situations. Thereafter, in operation 2004, the NTN thermal handling module 226 determines whether the message is directed to the emergency number (e.g. 911). If the NTN thermal handling module 226 determines that the message is not directed to the emergency number, at operation 2006, the NTN thermal handling module 226 may be configured to queue the message to be sent when there is no longer thermal heating at the UE 202. Alternatively, if the NTN thermal handling module 226 determines that the message is directed to the emergency number, the NTN thermal handling module 226 may be configured to apply thermal budget extension or exception to the thermal management algorithm for the emergency message at operation 2008. In an embodiment, the thermal budget is extended according to equation (1) when the emergency message is pending so that the emergency SMS is sent out.

[0149] Thermal mitigation temperature in NTN = Thermal mitigation temperature in TN (TN_THR) + T (budget of a few more degrees) = (1)

[0150] In another embodiment, the NTN thermal handling module 226 may be configured to limit all or some of the services running on the UE 202 when the temperature is between an actual thermal mitigation temperature (TN_THR) and a new thermal mitigation temperature (TN_THR) +T. This ensures that the budget extension only benefits the emergency services. In yet another embodiment, the NTN thermal handling module 226 may be configured to selectively exclude some signaling from thermal mitigation so that the emergency message is not restricted. The exceptions are only temporary and thermal mitigations are enforced again once the emergency message is sent out.

[0151] Finally, in operation 2010, the emergency message is sent. The discussion of the above solution scenario is based on the emergency message, however, it should be understood that the same is applicable for an emergency call and like as well.

[0152] Referring to Fig. 20B, at operation 2012, the UE 202 camps on the NTN. At operation 2014, a thermal situation arises at the UE 202 because of, but not limited to, the prolonged NTN usage. The operations 2016-2018 of Fig. 20B are similar to the operation 2008 described with reference to Fig. 20B and the description of the same has been omitted for the sake of brevity.

[0153] Figure 21 illustrates one or more problem scenarios associated with the DDS switch between the TN and the NTN subscriptions, according to the related art.

[0154] Referring to Fig. 21, the UE 202 is capable of accessing the NTN services on only one of the subscriptions (e.g. on SIM2) and the DDS SIM (e.g. SIM1) does not have NTN capability. In the scenario of Fig. 21, the UE 202 is in service on the TN (through SIM1 which does not have NTN capability) and moves to a region where NTN PLMNs are available. After a while, the UE 202 goes out of service on SIM1 and since the DDS is set to SIM1 which does not support the NTN, the UE 202 remains out of service, as shown in block 2102, and requires manual intervention to acquire services.

[0155] Figure 22 illustrates one or more solution scenarios corresponding to the one or more problem scenarios of Fig. 21, according to one or more embodiments of the present disclosure.

[0156] Referring to Fig. 22, initially, when the UE 202 is in service on the TN (through SIM1), the NTN FPLMN handler module 222 stores all the NTN PLMNs available at the location of the UE 202 in the FPLMN list, as shown in block 2202. At operation 2204, when the UE 202 goes out of service on both subscriptions, the NTN FPLMN handler module 222 releases the available NTN PLMNs from the FPLMN list. Thereafter, at operation 2206, the UE 202 temporarily switches the DDS to SIM2 which is capable of the NTN services, and tries scanning for service on the NTN frequencies. Finally, at operation 2208, the NTN selection module 218 selects the best NTN PLMN for the UE 202 to camp on and the UE 202 turns on the NTN_MODE. In an embodiment, the UE 202 can store the available services / subscriptions for the NTN and the TN services for each subscription. In an embodiment, when the UE 202 goes out of service in the TN (i.e. on SIM1), the UE 202 automatically triggers a scan for the available NTN PLMNs on the other subscription (e.g. SIM2). Similarly, when the UE goes out of service on the NTN-capable SIM (i.e. SIM2), the UE 202 triggers service acquisition through the TN for either subscription and switches the DDS automatically.

[0157] The present disclosure provides a solution to the UE 202 to optimally select the best NTN SIM profile and network in a single / dual SIM scenario. Specifically, the present disclosure optimizes the selection of an NTN PLMN where there are multiple options available to the UE thereby enriching user experience, reducing power consumption at the UE, and avoiding NTN overload. The present disclosure also optimizes NTN scanning in order to prevent unnecessary power consumption. Thus, the present disclosure provides an improved UE performance and user experience whilst providing the best NTN service available, when required. Moreover, the present disclosure provides prioritization of emergency SMS and a higher success rate on the UEs. The present disclosure also prevents the UE from camping on NTN PLMNs until necessary.

[0158] Some example embodiments disclosed herein may be implemented using processing circuitry. For example, some example embodiments disclosed herein may be implemented using at least one software program running on at least one hardware device and performing network management functions to control the elements.

[0159] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0160] The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein.

[0161] Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

[0162] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

Claims

1.A method (600) for performing Non-Terrestrial Network (NTN) selection by a User Equipment (UE) (202), the method comprising:determining (602) an unavailability of network services on a Terrestrial Network (TN);in response to determining the unavailability of the network services on the TN, identifying (604) a plurality of NTN Public Land Mobile Networks (PLMNs) available at the location of the UE (202);ranking (606) each of the identified plurality of NTN PLMNs based on one or more predefined parameters including at least one of emergency service support capability, strongest RSRP, transmission power requirement, data support capability, content-rich services support capability, SMS / MMS support capability, and available power level in the UE; andselecting (608) an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking.2.The method (600) as claimed in claim 1, the method comprising:disabling access to the identified plurality of NTN PLMNs in response to determining a presence of network services on the TN.3.The method (600) as claimed in claim 2, wherein disabling access to the identified plurality NTN PLMN comprises:adding the identified plurality of NTN PLMNs to a Forbidden PLMN (FPLMN) list in the UE (202).4.The method (600) as claimed in claim 1, wherein the TN comprises at least one of a Wi-Fi network, a Wi-Fi associated network, a 3GPP terrestrial network access, and a non-3GPP terrestrial network access.5.The method (600) as claimed in claim 1, wherein for the UE (202) with Multi-Enabled Profile (MEP) support, the method comprises performing one of:adding a Home PLMN (HPLMN) with NTN access to the identified plurality of NTN PLMNs; oradding a Visitor PLMN (VPLMN) with NTN access to the identified plurality of NTN PLMNs, wherein the VPLMN is present in the Operator preferred PLMN (OPLMN) list of the UE (202) with MEP support.6.The method (600) as claimed in claim 1,wherein the one or more predefined parameters comprises at least one of network capabilities, available network resources, and an associated radio cost.7.The method (600) as claimed in claim 1,wherein the ranking of the identified plurality of NTN PLMNs is further based on available power level in the UE (202).8.The method (600) as claimed in claim 1,wherein the method comprises prioritizing emergency messages on the selected NTN PLMN based on a predetermined priority assigned to a recipient or adjusting a back-off timer.9.A system (200) to perform Non-Terrestrial Network (NTN) selection by a User Equipment (UE) (202), the system comprising:memory storing instructions and comprising one or more storage media (208);at least one processor (206) in communication with the memory (208), the at least one processor (206) configured to:determine an unavailability of network services on a Terrestrial Network (TN);in response to determine the unavailability of the network services on the TN, identify a plurality of NTN Public Land Mobile Networks (PLMNs) available at the location of the UE (202);rank each of the identified plurality of NTN PLMNs based on one or more predefined parameters including at least one of emergency service support capability, strongest RSRP, transmission power requirement, data support capability, content-rich services support capability, SMS / MMS support capability, and available power level in the UE; andselect an NTN PLMN among the identified plurality of NTN PLMNs with a highest ranking.10.The system (200) as claimed in claim 9, the processor (206) configured to:disable access to the identified plurality of NTN PLMNs in response to determining a presence of network services on the TN.11.The system (200) as claimed in claim 10, wherein to disable access to the identified plurality NTN PLMN, the processor (206) is configured to:add the identified plurality of NTN PLMNs to a Forbidden PLMN (FPLMN) list in the UE (202).12.The system (200) as claimed in claim 9, wherein the TN comprises a Wi-Fi network, a Wi-Fi associated network, a 3GPP terrestrial network access, and a non-3GPP terrestrial network access.13.The system (200) as claimed in claim 9, wherein for the UE (202) with Multi-Enabled Profile (MEP) support, the processor (206) is configured to perform one of:add a Home PLMN (HPLMN) with NTN access to the identified plurality of NTN PLMNs; oradd a Visitor PLMN (VPLMN) with NTN access to the identified plurality of NTN PLMNs, wherein the VPLMN is present in the Operator preferred PLMN (OPLMN) list of the UE (202) with MEP support.14.The system (200) as claimed in claim 9, wherein the one or more predefined parameters comprises at least one of network capabilities, available network resources, and an associated radio cost.15.The system (200) as claimed in claim 9, wherein the ranking of the identified plurality of NTN PLMNs is further based on available power level in the UE (202).

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