Secure element application and corresponding secure element for triggering a mobile device to perform a preferred network selection procedure - Patents.com

Abstract

The present invention relates to a secure element application for triggering a mobile device to perform a preferred network selection procedure for attaching to a private network after an optimal period of time and after at least a specific location change, the optimal period of time and the specific location change being learned from a continuous learning phase, during which the application performs the following steps: - Attach to a private network: - a known method for triggering a mobile device to perform a network selection, or - triggering the mobile device to perform network selection in a known location where a private network is expected to be available; or - Varying the time and frequency at which the mobile device is triggered to make a network selection after a given location change. including an order to try the case through successive trials, The optimal time period is derived from a previously recorded time period measured from a location change event to a successful switch to the private network.

Description

[Technical field]

[0001] The present invention relates to telecommunications and more precisely to secure elements such as SIM cards, USIMs, UICCs (Universal Integrated Circuit Cards) such as eUICC (embedded UICC) or iUICC (integrated UICC). These secure elements cooperate with terminals (User Equipment, UE for short) such as for example smartphones, mobile phones, PDAs or IoT devices. These terminals are also called devices hereafter. [Background technology]

[0002] The secure element has the purpose of establishing and securing the communication between the terminal and the telecommunications network.

[0003] There are two main types of telecommunications networks: public and private. Public telecommunications networks are also called PLMNs (Public Land Mobile Networks). A PLMN can be a Home PLMN (HPLMN) or a Visited PLMN (VPLMN).

[0004] For example, in schools, airports, large factories, energy utilities, manufacturing sites, ports or offshore platforms, private cellular networks may be installed and access to these networks may be restricted to given identified users of terminals covered by these private cellular networks.

[0005] The object of the invention is to switch from a globally accessible public network to a locally accessible private network, which is initiated by the secure element as soon as it detects the presence of a private network (the terminals with which it cooperates are covered by the private network), and which is realized in particular to minimize communication costs, address security risks and narrow the attack surface.

[0006] A private network as used herein is also known as a non-public network (or NPN in the 3GPP specifications) or referred to as a mobile private network.

[0007] 3GPP does not allow a UE to search for higher priority PLMNs when camped on a HPLMN or EHPLMN (Equivalent Home PLMN).

[0008] Existing solutions for switching from a globally accessible public network to a local private network rely on either: - configuring a global public network as a Visited PLMN (VPLMN), which has associated issues, e.g. regarding user experience or due to user preferences to restrict data access when roaming and by default mobile terminals are set up to prevent data usage when roaming; - using SIM toolkit location status events sent by the ME to the USIM, however such an approach is not optimal when the private network is not immediately available after such an event; - Support by the ME of a specific method for the USIM to force the ME to perform a network selection procedure.

[0009] However, these existing methods impact either battery usage or user experience, for example long delays before switching to the private network or frequent UE re-initialization periods (unavailable for normal use). Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, the technical problem that this invention is intended to solve is: how to force an ME to switch from a globally accessible public network to a local private network as quickly as possible, automatically and with minimal impact on battery consumption and usability, without modifying the ME. [Means for solving the problem]

[0011] this is: - selecting a method supported by the ME for instructing the ME to perform network selection; - determining the earliest time at which the ME should perform a network selection procedure; - Steps to minimize service interruptions caused by the switching procedure in order to optimize battery consumption This is achieved by a method comprising:

[0012] More precisely, the invention proposes a secure element application for triggering the mobile device to perform a preferred network selection procedure for attaching to a private network after an optimal time period and at least after a specific location change, the optimal time period and the specific location change being learned from a continuous learning phase, during which the application: - Attach to a private network: - a known method for triggering a mobile device to perform a network selection, or - triggering the mobile device to perform network selection in a known location where a private network is expected to be available; or - Varying the time and frequency at which the mobile device is triggered to make a network selection after a given location change. including an order to try the case through successive trials, The optimal time period is derived from a previously recorded time period measured from a location change event to a successful switch to the private network.

[0013] Preferably, the known method for triggering a preferred network selection procedure comprises: - modifying the IMSI of the secure element, or - Clearing the LOCI file on the Secure Element, or - To steer roaming refreshes, or - Indicating via AT command to the mobile device to go into idle mode, or - Any combination of these above methods Includes.

[0014] Advantageously, the known locations are: - pre-configured in the secure element application, or - configured in the secure element application by a remote server, or - Learned through successive trials at different locations, or - Based on network denial events It is.

[0015] Preferably, modifying the frequency with which the mobile device is triggered to perform a network selection consists in triggering it less frequently to obtain the best trade-off between battery consumption and time to switch to a private network.

[0016] The invention also relates to a secure element containing such an application.

[0017] The invention will be better understood by reading the following description of a preferred embodiment of the invention with reference to FIG. 1 , which represents a UE (consisting of an ME part and an SE / USIM part) moving from a first HPLMN cell to a second HPLMN cell, with at least a part of a private network being within the coverage of the second HPLMN cell. [Brief description of the drawings]

[0018] [Figure 1] The diagram represents a public network 10 (here an HPLMN, but which may also be, for example, a VPLMN or an EHPLMN). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The HPLMN 10 includes two HPLMN cells, a first HPLMN cell A referenced as 11 and a second HPLMN cell B referenced as 12. The coverage of the HPLMN cell 12 covers at least a portion of the coverage of a private 5G (or 4G / 3G / 2G, WLAN or wireless network in general) private network 13.

[0020] A UE 14 , consisting of an ME and a secure element SE (eg USIM), is in a first step covered by cell 11 and is moving towards cells 12 and 13 .

[0021] In a second step, the UE 14 reaches the edge of cells A and B of the HPLMN and camps on cell B.

[0022] When requested by the SE to send an event regarding a location change, the UE 14 sends the location change event to the SE.

[0023] The SE determines (e.g., by searching a locally stored lookup table) that the private 5G network 13 is close to cell B (i.e. there is a high probability that a network selection procedure attempt by the ME of the private network will be successful), but does not yet know when exactly to switch to the private 5G network.

[0024] When the UE 14 comes within the coverage of cell B 12, the SE starts a timer T and attempts to switch and connect to the private 5G network 13 at various frequencies.

[0025] Once the private 5G network is reached (i.e., the UE 14 is under the radio coverage of the private network), in a third step, the SE's attempt to switch to private 5G is successful and the UE 14 is able to connect to the private 5G network 13.

[0026] The USIM then stops timer T, stops the handover attempt process and saves the value T0 of timer T. Value T0 thus corresponds to the duration (time period) that the ME has needed from the time it enters cell B 12 until it reaches within cell 13.

[0027] The next time the SE receives an event from the ME indicating that the ME has reached cell B 12, the SE starts timer T again (after resetting) and waits for timer T to reach a value T0* derived from T0 before beginning the switch attempt process.

[0028] When the UE 14 is able to connect to the private 5G network 13, the UE 14 stops the switching procedure and stores the new value T1 of the timer T.

[0029] The next time UE 14 reaches cell B, the SE derives a new value T1* from T0, T0* and T1.

[0030] After several epochs of the above learning process, the SE may estimate one or more values ​​of timer T such that the private 5G network may be accessible with a higher probability than a set fixed threshold.

[0031] As a result, the SE may reduce the time and frequency of the switching attempt procedures, thereby reducing the UE's battery consumption due to the switching attempts.

[0032] Regarding the learning algorithm, two alternatives are possible: one based on a neural network model (e.g., LSTM - Long Short-Term Memory), and a second, more traditional algorithm based on triplets of programmatically tuned parameters.

[0033] These algorithms are described below.

[0034] Neural network (e.g., LSTM) based algorithms can be used to improve Time of Arrival (ToA) predictions.

[0035] ToA is the time period between the moment the UE 14 reaches the target cell (i.e. the cell where there is a high probability that it is under private network coverage) and the moment the MPN (Mobile Private Network) is successfully selected.

[0036] Radio cells are identified by their cell identifiers broadcasted on the air interface by radio-based stations. A target cell is identified in particular by its target Cell-ID. The applet may know the target Cell-ID of a target cell, for example by pre-configuration by the home PLMN or private network operator, or after a trial-and-error phase.

[0037] The present invention uses a reinforcement learning algorithm to improve a machine learning model (called MODEL) (e.g., based on an LSTM or multiple layers of an LSTM neural network).

[0038] The input of the MODEL contains the sequence of Cell-IDs received by the applet from successive location update events until a location update event contains the target Cell-ID, indicating that the target Cell-Id has been reached.

[0039] The output of MODEL is ToA.

[0040] During the reinforcement learning phase: - The MODEL is provided as input with a consecutively received list of Cell-IDs. - A predicted Time of Arrival (pToA) is generated for each input by the MODEL. - The error between (Err=pToA-gtToA) is calculated: ○ Predicted time of arrival (pToA) and ○ Ground truth Time of Arrival (gtToA) measured by the applet - The calculated error (Err) is back-propagated within the training MODEL to adjust the MODEL internal parameters until the MODEL is able to provide an aggregate Err below a specified threshold (e.g., the average square root of the sum of the squared errors over the validation batch of data).

[0041] The training application records the set of Cell-IDs for reinforcement training of the model.

[0042] The set of Cell-IDs recorded by the training application is the last N Cell-IDs before the target cell is reached, including the target CellID.

[0043] The training application also records the corresponding ground truth gtToA associated with the set of Cell-IDs.

[0044] A triplet-based learning algorithm to minimize the time to successfully select a private network and minimize the number of selection attempts when the target cell is reached: - The applet makes a first attempt to select a private network after a long period of time of value TL (e.g., 10 minutes). - If a private network could not be selected during this first attempt: ○ The applet makes subsequent attempts after a shorter period of time of value TS (e.g., 1 minute). ○ Until the MVP is selected - if a private network could have been selected during the first attempt when TL expires, TL is decreased by Nd times TS (new_TL=old_TL-Nd*TS) and this new value is used the next time a device coming from a public mobile network reaches a target cell; - if a private network cannot be selected upon expiration of a long period TL and is successfully selected after N expirations of TS, If N is greater than Nd, TL is increased by (N-Nd) times TS (new_TL=old_TL+(N-Nd)*TS). If N is less than or equal to Nd, TL is unchanged. This can be attributed to the fact that.

[0045] Therefore, Nd is used to reduce the long term period TL in order to have the opportunity to select the private network at an earlier point in time when the target cell is reached.

[0046] A triplet value (TL, TS, Nd) may be associated with each or a group of target cells in the target cell list.

[0047] Therefore, the invention proposes to use the secure element application to trigger the mobile device to perform a preferred network selection procedure for attaching to a private network after an optimal time period and at least after a specific location change, the optimal time period and the specific location change being learned from a continuous learning phase (where the application runs permanently) and during this continuous learning phase the application: - Attach to a private network: - a known method for triggering a mobile device to perform a network selection, or - triggering the mobile device to perform network selection in a known location where a private network is expected to be available; or - Varying the time and frequency at which the mobile device is triggered to make a network selection after a given location change. including an order to try the case through successive trials, The optimal time period is derived from a previously recorded time period measured from a location change event to a successful switch to the private network.

[0048] The optimal time period is derived from a previously recorded time period measured from a location change event during which the private network is expected to be available until a successful switch from the HPLMN to the private network.

[0049] Known methods for triggering a preferred network selection procedure include, but are not limited to, the following methods: - Modifying the IMSI of the USIM (this is the slowest method), - Clearing the LOCI file in the USIM, - Steering roaming refresh; - indicating to the ME via an AT command to go to idle mode; - and any combination of these above methods Includes.

[0050] Target locations known by the application can be, for example: - preconfigured in the UICC application; or configured in the UICC application by a remote server, or learned through successive trials at various locations, - Or based on network denial events Either:

[0051] Modifying the frequency with which the mobile device is triggered to perform network selection consists in triggering it less frequently to obtain the best trade-off between battery consumption and time to switch to a private network.

[0052] The invention also relates to a secure element containing such an application.

[0053] The main advantages offered by the present invention are: - Seamless switching: no user intervention; - Minimizing switchover delays when a private network becomes available; - Allow the device to spend the maximum amount of time on a private network; - Minimize battery consumption by optimizing timing from changes in location (where private networks are expected to be at the edge of public networks) Includes.

[0054] There are two use cases for this invention: - Use Case 1: SEs learn when to switch to a private network in a combination of existing solutions. - Use case 2: In "standalone mode", the SE is configured (by the MNO) with the Cell B identity in which the private network is located, and then learning starts when the terminal enters the coverage of Cell B.

[0055] In summary, the present invention relies on actual trials of what features are supported by actual terminals, which may change over time depending on the environment, e.g., radio coverage changes, obstacles, etc., to select the most time-efficient procedure for performing a network selection procedure. The present invention also relies on actual trials to predict when to make a switch based on the location and trajectory of the device, when previous methods rely only on location changes. Finally, parameters learned for one or several devices presenting the same usage profile may be shared with other devices presenting the same usage profile.

Claims

1. 1. A secure element application for triggering a mobile device to perform a preferred network selection procedure for attaching to a private network after an optimal time period and after at least a specific location change, said optimal time period and said specific location change being learned from a continuous learning phase, said application comprising: - attaching to said private network, - a known method for triggering the mobile device to perform a network selection, or triggering the mobile device to perform network selection at a known location where the private network is expected to be available; or - Varying the time and frequency at which the mobile device is triggered to perform a network selection after a given location change. including an order to try the case through successive trials, The optimal time period is derived from a previously recorded time period measured from a location change event to a successful switch to the private network.

2. The known method for triggering a preferred network selection procedure comprises: - modifying the IMSI of said secure element, or - clearing the LOCI file of said secure element, or - Steering roaming refreshes, or indicating via an AT command to the mobile device to go into idle mode, or - Any combination of these above methods The secure element application of claim 1 , comprising:

3. The known location is - pre-configured in the secure element application, or - configured in said secure element application by a remote server, or - learned through successive trials at different locations, or A secure element application according to claim 1 or 2 based on a network denial event.

4. A secure element application according to any one of claims 1 to 3, wherein said modifying the frequency with which the mobile device is triggered to perform a network selection consists in triggering less frequently to obtain the best trade-off between battery consumption and time to switch to the private network.

5. A secure element comprising an application according to any one of claims 1 to 4.

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