Method for configuring radio access technology utility for user equipment registed to a mobile network, user

Abstract

A method of configuring radio access technology, RAT, utilization of a user equipment, UE, for registering with a mobile network is provided. The method comprises transmitting, from a core network entity to a UE, an indication comprising one or more RATs restricted for the UE, where reception of the indication causes the UE to suppress registration attempts on the one or more restricted RATs when the indication is effective.

Description

TECHNICAL FIELD

[0001] The present invention relates to configuring radio access technology, RAT, utilization in a mobile network. In particular, the present invention relates to restricting a UE from registering to a particular RAT during a cell selection and / or reselection procedure.

[0002] Glossary RAT - Radio Access Technology TS - Technical Specification PLMN - Public Land Mobile Network SST - Slice / Service Type NAS - Non-Access Stratum AS - Access Stratum SIM - Subscriber Identity Module SNPN - Standalone Non-Public Network CAG - Closed Access Group NSAG - Network Slice AS Group EPS - Evolved Packet System 5GS - 5G System SA - Standalone NG-RAN - Next Generation Radio Access Network MME - Mobility Management Entity TAI - Tracking Area Identity IE - Information Element RAN - Radio Access Network UE - User Equipment BS - Base Station ABS - Advanced Base Station BTS - Base Transceiver Station BSS - Basic Service Set ESS - Extended Service Set AP - Access Point NB - Node B (Radio Base Station Receiver) eNB - Evolved Node B gNB - Next Generation Node B TRP - Transmission and Reception Point PS - Processing Server TE - Terminal Equipment MS - Mobile Station MT - Mobile Terminal UT - User Terminal SS - Subscriber Station PDA - Personal Digital Assistant CDMA - Code Division Multiple Access FDMA - Frequency Division Multiple Access TDMA - Time Division Multiple Access OFDMA - Orthogonal Frequency Division Multiple Access SC-FDMA - Single Carrier Frequency Division Multiple Access MC-FDMA - Multi Carrier Frequency Division Multiple Access UTRA - Universal Terrestrial Radio Access GSM - Global System for Mobile Communications (2G) GSMA - GSM Association GPRS - General Packet Radio Service EDGE - Enhanced Data rates for GSM Evolution IEEE - Institute of Electrical and Electronics Engineers E-UTRA - Evolved UTRA UMTS - Universal Mobile Telecommunications System (3G) E-UMTS - Evolved UMTS 3GPP - 3rd Generation Partnership Project DL - Downlink UL - Uplink LTE - Long Term Evolution (4G) LTE-A - Advanced LTE NR - New Radio (5G) FDD - Frequency Division Duplex TDD - Time Division Duplex CRS - Cell-specific Reference Signal CSI-RS - Channel State Information Reference Signal FPGA - Field Programmable Gate Array ASIC - Application-Specific Integrated Circuit DSP - Digital Signal Processor CD-ROM - Compact Disc Read Only Memory DVD-ROM - Digital Versatile Disc Read Only Memory ROM - Read Only Memory RAM - Random Access Memory EEPROM - Electrically Erasable Programmable Read Only Memory EPROM - Erasable Programmable Read Only Memory BACKGROUND

[0003] Most mobile networks ("cellular networks") offer selection of different radio access technologies (RATs) for communication with user equipment (UEs). A UE can be permitted to connect to a mobile network via any of the available RATs, and the UE can select a RAT based on selection criteria (e.g., signal strength or connection speed). However, in some cases, it can be desirable for a mobile network to limit the RATs on which a UE is permitted to connect to a subset of the available RATs.

[0004] For example, some mobile networks offer national roaming services to allow customers of other mobile networks (in the same country) to use their networks. To ensure continued service for their own customers, a mobile network that offers national roaming can limit national roamers to certain RATs. For example, a mobile network can permit national roamers to connect via 4G but not via 5G. Roaming agreements between mobile networks can specify which RATs are allowed and which RATs are limited. A national roamer that is a customer of one mobile network can be permitted to register with another mobile network via the allowed RATs but not via the limited RATs.

[0005] If a UE attempts to register on a RAT that is limited by the mobile network, the network can determine that the RAT is limited for the UE and send a rejection message in response. After an unsuccessful registration, the UE can subsequently register via the allowed RATs.

[0006] However, unsuccessful registration attempts place a signaling burden on the network. Moreover, the time it takes for a UE to register via a different RAT can be quite long (up to 12 minutes in some cases).

[0007] Unrestricted use of RATs can lead to technical challenges, inefficiency in use of network resources, and can potentially compromise quality of service, and thus impact user experience. Quantitative drive test results have been presented that depict the duration of service interruption relying on current non-access stratum (NAS) mechanisms of networks sending registration rejection messages containing rejection cause codes to regulate the utilization of NG-RAN. In addition, other drawbacks can include increased signaling load in 5GS networks and security issues arising from the possibility of sending rejection messages without integrity protection.

[0008] There are indeed service requirements that enable network operators to regulate the utilization of specific access technology combinations within a PLMN.

[0009] Clause 5.2.1 of 3GPP TS 38.304 describes that "NAS can control the RAT(s) in which cell selection shall be performed, e.g. by indicating the RAT(s) associated with the selected PLMN, and by maintaining a list of forbidden registration areas and a list of equivalent PLMNs. The UE shall select a suitable cell based on RRC IDLE or RRC INACTIVE state measurement results and cell selection criteria." Where 3GPP TS 38.304 describes that "NAS can control the RAT(s) in which cell selection shall be performed", this refers to the case where a registration attempt is received on a forbidden RAT, the NAS sends a reject message (such as the REGISTRATION REJECT message in 5G).

[0010] 3GPP TS 38.304 relates to 5G. 3GPP TS 36.304 describes the equivalent procedure in 4G.

[0011] The procedure for controlling the RAT(s) during cell selection is further described in 3GPP TS 23.122, which in clause 3.1 describes that "In automatic PLMN selection, the MS shall not consider a PLMN included in the list of 'PLMNs where E-UTRAN is not allowed' as a PLMN selection candidate for E-UTRAN access technology, unless no other PLMN is available. This does not prevent its selection if such a PLMN is available in another RAT". This document describes that the UE can maintain a list of PLMNs where E-UTRAN is not allowed in response to receiving a reject message (such as the REGISTRATION REJECT message in 5G with cause #15, as specified in 3GPP TS 24.301).

[0012] In another prior art scenario, clause 6.3.2 of 3GPP TS 22.261 describes that "Based on operator policy, the 5G system shall support guiding the UE to select certain 3GPP access network(s)" and "Based on operator policy, the 5G system shall be able to dynamically offload a portion of traffic (e.g. from 3GPP RAT to non-3GPP access technology) taking into account traffic load and traffic type". These prior art approaches exist to support load balancing between RATs, but do not configure restricted RATs for the UE.

[0013] In an alternative prior art scenario, allowed RATs can be configured in the subscription data in the SIM of the UE. This is described in clause 6.19 of 3GPP TS 22.261, which states that "The network operator can populate the operator controlled PLMN selector list with associated access technology identifiers stored in the 5G UE, where the PLMN / RAT combination enables access to SSTs available to the 5G UE with the associated subscription. Typically during roaming scenarios, the UE uses the list of PLMN / RAT combinations for PLMN selection if available".

[0014] This scenario is further described in Table 4.2-1 of 3GPP TS 38.304, which describes "List of PLMNs in order of priority according to TS 23.122 [9]. [...] For each PLMN, the associated RAT(s) can be set". Clause 4.4.3 of TS 23.122 describes that "The data file in the SIM includes the associated access technologies for each PLMN entry".

[0015] Clause 7.1 of 3GPP TS 22.011 describes that "It shall be possible to indicate in the subscription data per subscriber the allowed categories of tracking / location / routing areas. It shall be possible to use this subscription information in the serving network to restrict the access of the subscriber to the categories of tracking / location / routing areas. At least, at least one of the following categories shall be available: a) GERAN; b) UTRAN; c) E-UTRAN; d) NG-RAN". The subscription data is provided on the SIM.

[0016] None of the available prior art provides a dynamic and efficient way to limit the RATs via which a UE can connect to a mobile network. SUMMARY

[0017] A method of configuring radio access technology, RAT, utilization for a user equipment, UE, registered to a mobile network is provided. The method comprises transmitting, from the mobile network to the UE, an indication comprising one or more RATs restricted for the UE, wherein upon the indication taking effect, reception of the indication causes the UE to refrain from registration attempts on the one or more restricted RATs (or even not to measure reference signals for the restricted RATs).

[0018] The indication comprising one or more RATs restricted for the UE can be transmitted from the UE to a core network entity of the mobile network.

[0019] The one or more RATs can be restricted from being used by the UE across the entire mobile network, or can be restricted in specific parts of the mobile network.

[0020] In some example prior art methods, the UE attempts to register on a restricted RAT, and the network sends a rejection message in response. In this scenario, after an unsuccessful attempt by the UE to register on a restricted RAT, the UE can subsequently connect via a permitted RAT. In contrast, in the proposed method, the core network entity proactively sends a list of restricted RATs to the UE, so that the UE does not attempt to register on a restricted RAT. The proposed method can thus reduce the incidence of UEs attempting to register on a restricted RAT, and thus reduce unnecessary signaling in the network resulting from such unsuccessful registrations. Network efficiency can therefore be improved as a result of the proposed method.

[0021] It should be noted that the signaling required to receive an attempt to register on a restricted RAT and send a rejection message in response requires significant resources. This is at least because the rejection message comes from the core network and must be transmitted to the UE via the non-access stratum (NAS). In order to do so, the UE must be connected to the core network via the access network (on the restricted RAT), and thus, all signaling required to establish this connection must be completed before the rejection message can be sent to the UE. In particular, once connectivity is established between the UE and the access network (e.g. a base station), a connection between the base station and the core network needs to be established in order to transmit the rejection message from the NAS to the UE, using core network resources and radio access network resources.

[0022] In contrast, the proposed method pre-configures the restricted RATs so that the UE does not attempt to register on a restricted RAT. This can thus reduce the signaling required to communicate this restriction to the UE and improve network efficiency.

[0023] In prior art scenarios, once the UE receives the rejection message, the UE can disable 5G for a short time or look for other tracking areas. As a result, the UE can experience a downtime period before it successfully connects to the mobile network via a permitted RAT. This downtime period is often quite large, and typically ranges from 22 seconds to 12 minutes. This downtime is bad for user experience, since the UE is not registered to the network during this time. It is also bad for the network, since the network is unable to reach the UE during this period. In contrast, the proposed method pre-configures the restricted RATs so that the UE does not attempt to register on a restricted RAT. Instead, the UE can attempt to register on a permitted RAT and successfully connect, without experiencing the downtime associated with an unsuccessful registration attempt on a restricted RAT.

[0024] As described before, in alternative prior art scenarios, the allowed RATs can be configured in the subscription data in the SIM of the UE in a static way (e.g. during an initial provisioning step). In contrast, the proposed approach is more flexible and allows the indication of the restricted RATs to be transmitted directly from the core network entity to the UE.

[0025] Advantageously, in the proposed approach, the indication of the restricted RAT(s) is transmitted to a specific UE. Thus, the list of restricted RAT(s) can be different for different UEs. For example, one or more specific RATs can be restricted for roamers, while normal subscribers can have access to those RAT(s). Thus, the proposed approach is more flexible compared to some prior art solutions, in which the specific RAT(s) can be restricted on a basis that is spread across the PLMN.

[0026] The approach can be used to configure the RAT utilization during cell selection and / or cell reselection. In other words, the same RAT(s) can be restricted for cell selection and cell reselection.

[0027] If the UE is already registered to a PLMN on an allowed RAT, the indication of the restricted RAT(s) can be transmitted to the UE by the network to prevent the UE from reselecting a restricted RAT. In case the UE loses signal and subsequently initiates cell selection, the UE can have previously received the indication of the restricted RAT(s) from the PLMN and can avoid the restricted RAT(s).

[0028] In the above described prior art scenario in which a rejection message is sent to the UE, the UE only learns that this one specific RAT is restricted (on which the registration attempt was unsuccessful). However, if other RATs are also restricted, the UE can attempt to register on those RATs, resulting in further rejection messages. In contrast, in some examples of the proposed approach, a list of restricted RATs can be transmitted to the UE (the indication can comprise multiple restricted RATs). Thus, the UE can be provided with additional information that can prevent unsuccessful registration attempts on other restricted RATs.

[0029] In some examples, the indication can further comprise a list of allowed RATs. The UE can only attempt to register on the allowed RATs indicated by the mobile network. Thus, the UE can not make any registration attempts on restricted RATs.

[0030] In other words, the indication can comprise a list of one or more restricted RATs on which the UE is not permitted to register and a list of one or more RATs on which the UE is permitted to register.

[0031] The one or more restricted RATs can be communicated to a particular UE. Thus, the restriction can be set on a per-UE basis rather than on a basis across a PLMN.

[0032] The core network entity can be in a core network of a mobile network (which can also be referred to as a “telecommunications network”).

[0033] The indication can further comprise one or more RATs that are allowed for the UE. In other words, the indication provides restricted and allowed RATs. By providing the allowed RATs to the UE, registration attempts on the restricted RATs can be reduced and network efficiency can be improved.

[0034] The indication can be communicated during a UE-initiated mobility-specific procedure.

[0035] The indication can be communicated during one or more of the following UE-initiated mobility-specific procedures: an initial attach procedure; a tracking area update procedure; a registration request procedure.

[0036] In 5G, the registration request procedure can be an initial registration (which can be similar to the attach procedure in pre-5G). Alternatively, the registration request procedure in 5G can be a mobility and periodic registration (which can be similar to the tracking area update procedure in pre-5G).

[0037] In other words, the indication can be communicated during a session management procedure or a mobility management procedure.

[0038] The procedures described above provide specific examples in which the indication can be communicated during a procedure related to a particular network technology. As described above, the indication can be communicated during an initial attach procedure or a tracking area update procedure in a 4G LTE network or a registration request procedure or a registration area update procedure in a 5G NR network. Likewise, the indication can be communicated during an attach procedure, a location area update procedure, or a routing area update procedure in other network technologies. The indication can be communicated during equivalent procedures in 6G and other network technologies. Although examples are provided with respect to procedures for communicating the indication to a UE using a 4G LTE network, the approach is not limited to 4G LTE networks.

[0039] In some specific examples, the indication can be communicated in an ATTACH ACCEPT message or a TRACKING AREA UPDATE ACCEPT message.

[0040] The indication can be communicated via a non-access stratum (NAS) functional layer between the UE and the core network.

[0041] The method can further comprise passing the indication from a NAS functional layer of the UE to an access layer, AS, functional layer of the UE.

[0042] The UE can be comprised of multiple functional layers, such as an application layer, a NAS layer, and an AS layer. The method can comprise receiving the indication of the restricted RAT from the network via the NAS layer and passing the indication to the AS layer. In other words, the UE can transfer the preference between the NAS layer and the AS layer. Thus, the AS layer of the UE can use the indication of the restricted RAT to suppress registration attempts on the restricted RAT. The selection of a particular RAT or cell during reselection is an AS layer function. However, since the indication of the restricted RAT comes from the NAS, the information can be passed between the layers.

[0043] The indication can be communicated with a security protection. For example, the indication can be communicated with integrity protection and / or ciphering.

[0044] Security protection is described in more detail in 3GPP TS 24.301, which is incorporated by reference.

[0045] In contrast to prior art methods, the proposed method can communicate the indication of the one or more restricted RATs from the core network to the UE in an "ACCEPT" message (e.g., during a successful mobility specific procedure such as an attach procedure or a tracking area update procedure) rather than through a rejected registration attempt. In this way, the indication is communicated in a message exchanged between the core network and the UE in any case. Thus, an unsuccessful registration attempt is not required to communicate this information to the UE, and additional signaling burden on the network associated with unsuccessful registration attempts and responses can be avoided.

[0046] The indication can be in effect until it is deleted or replaced by another indication of a restricted RAT.

[0047] In one example, the indication can be deleted upon receipt of a predetermined message (such as an ATTACH ACCEPT or TRACKING AREA UPDATE ACCEPT) that does not include the indication of the restricted RAT.

[0048] In one example, the mobile network can update the list of one or more restricted RATs by sending a new indication of a restricted RAT to replace a previously in effect indication. The new indication can be received from the same network entity or from a different network entity.

[0049] The new indication can include restricted and allowed RATs.

[0050] In another example, the mobile network can remove the restriction by sending a predetermined message that does not include an indication of the restricted RAT. Reception of the message can cause the UE to delete the previously validated indication. This can be used when the mobile network removes the restriction on the RAT for the UE.

[0051] In another example, the UE can register in different areas in which different RAT restrictions apply (or in which no RAT restrictions apply). Thus, the UE can receive a predetermined message that includes an updated indication of the restricted RAT or no indication of the restricted RAT at all. Reception of the message can cause the UE to replace the previously validated indication with the new RAT restriction. In the latter case, where the message includes no indication of the restricted RAT, the UE can be configured to delete the previously validated indication. Thereby, the UE can be configured to utilize the RAT that was previously restricted.

[0052] In another example, the UE can register to a different mobile network that does not impose any restrictions on the RAT (e.g., if the UE returns from a roaming network to a home network). Thus, the UE can receive a predetermined message from the different mobile network that does not include an indication of the restricted RAT. Thus, the UE can delete the previously validated indication. Thereby, the UE can be configured to utilize the RAT that was previously restricted.

[0053] The indication can include an expiration time and the indication can be valid until it expires.

[0054] The method can further include monitoring one or more reference signals corresponding to one or more cells operating via one or more RATs that are not restricted; and evaluating cell selection and / or cell reselection criteria on the one or more reference signals. The method can further include refraining from monitoring reference signals corresponding to cells operating via the one or more restricted RATs.

[0055] In some examples, the "one or more RATs that are not restricted" are the "one or more allowed RATs" included in the indication.

[0056] The method can further include storing the one or more RATs that are restricted for the UE on a subscriber identity module (SIM) of the UE.

[0057] In some examples, the method can further include storing the one or more RATs that are allowed for the UE on the SIM.

[0058] The indication can be valid for the entire mobile network (e.g., PLMN).

[0059] Alternatively, the indication can further include one or more areas in which the indication is valid.

[0060] The one or more areas can include one or more of: one or more location areas, one or more routing areas, one or more cells, one or more tracking areas, one or more geographic areas, one or more registration areas, and one or more network areas.

[0061] Access to one or more RATs can be allowed / restricted based on a location that can be represented by a geographic location, a tracking area, and so on. The location of the UE can be determined based on location information from a satellite navigation system, cell information received from a base station, use of a private network by the UE (e.g., if the private network is localized to a particular area), and so on.

[0062] The method can further include determining that the UE is located in one of the one or more areas in which the enforcement is indicated.

[0063] In some examples, determining that the UE is located in one of the one or more areas in which the enforcement is indicated can include using GPS coordinates from the UE, using a tracking area, a registration area, a location area, a routing area, and / or a cell ID received from a base station, and / or using an identifier received from a network access point.

[0064] In some examples, use of a private network by the UE can be used to indicate an area.

[0065] The method can further include performing data analysis on the UE via the RAT on which the UE is registered. The method can further include identifying, from the data analysis, an occurrence of an event, where the event causes the mobile network to limit utilization of the RAT on which the UE is registered. The method can further include transmitting, from the core network entity to the UE, an indication that the UE is to limit the RAT on which the UE is registered.

[0066] In some examples, the method can include measuring data usage of the UE via the RAT on which the UE is registered; determining that the measured data usage of the UE indicates that utilization of the RAT should be limited (e.g., because the data usage via the RAT exceeds a threshold); and transmitting an indication that the UE is to limit the RAT.

[0067] The reception of the indication that a particular RAT is limited, when the enforcement is indicated, can cause the UE to refrain from registration attempts on the particular RAT (or can cause the UE to not measure reference signals for the particular RAT at all).

[0068] The method can further include determining that the UE is a national roamer, where the RAT limitation applies to national roamers; and sending the indication of the one or more limited RATs in response to the determination.

[0069] If the UE attempts to register directly to the restricted RAT of the mobile network, the core network can send a reject message to the UE (e.g., the core network can send a REGISTRATION REJECT message to the UE in 5G). For example, if the UE has not previously attached to the mobile network via the allowed RAT, it can not have received an indication of the restricted RAT from the mobile network. Thus, it can attempt to register via the restricted RAT.

[0070] A user equipment, UE, configured to perform the above described methods is also provided.

[0071] A network entity or server (e.g., a core network entity such as a mobility management entity) configured to perform the above described methods is also provided.

[0072] A computer program comprising instructions which, when executed on a processor, cause the processor to perform the above described methods is also provided. BRIEF DESCRIPTION OF DRAWINGS

[0073] The application will be described with reference to the non-limiting examples illustrated in the following drawings.

[0074] Figure 1 An example system is illustrated.

[0075] Figure 2 A flowchart of an example method is illustrated.

[0076] Figure 3 An example user equipment is illustrated.

[0077] Figure 4 An example network entity is illustrated. DETAILED DESCRIPTION

[0078] An example system is illustrated in Figure 1 An example system is illustrated in FIG. 1. A mobile network 100 includes an access network 120 and a core network 140. A UE 110 communicates with the access network via an access stratum (AS) 130. The UE 110 communicates with the core network 140 via a non-access stratum (NAS) 150.

[0079] The UE 110 can connect to the mobile network 100 via a plurality of different radio access technologies (RATs). There can be a number of reasons why the mobile network needs to restrict access via one or more RATs for a particular UE or group of UEs. In an example use case, PLMN #A and PLMN #B within the same country have reached a roaming agreement enabling customers to roam nationwide during which only 2G and 4G radio access technologies (RATs) are to be utilized.

[0080] A large number of roamers residing on a 5G network may be undesirable because capacity in the 5G network may be limited. Therefore, 5G may be excluded from roaming agreements. Consequently, utilization of 5G RATs may be restricted for UEs during roaming. In some examples, 5G RATs may be restricted nationwide or may be allowed only within specific geographic regions.

[0081] To achieve this exclusion, existing standards provide a workaround: If a UE attempts to access a network on a restricted RAT, a REJECT message is sent from the core network.

[0082] Instead of relying on the network to passively send a rejection cause code as in the prior art scenario described above, the network can send an indication of the restricted RAT(s) directly to the UE. For example, a list of restricted RATs can be included in the Attach Accept and / or Tracking Area Update Accept message(s) to the UE. This proactive approach can reduce the number of unnecessary UE registrations to restricted RATs (e.g., in some examples, 5GS).

[0083] Unnecessary UE registrations to restricted RATs may cause subscribers (eg, roaming subscribers in the examples described above) to experience extended downtime periods. This unnecessary downtime may be reduced by the proposed method.

[0084] No input from the GSMA is required, as subscribers have the ability to roam between 4G networks and access services seamlessly.

[0085] There are no service requirements that enable network operators to regulate the utilization of specific access technology combinations within a PLMN. For example, 3GPP TS 22.261, 3GPP TS 22.011, 3GPP TS 38.304, 3GPP TS 36.304 and 3GPP TS 23.122, as described above, are all incorporated by reference.

[0086] When an inbound roamer / UE from PLMN#A (already attached or not yet attached in the Evolved Packet System (EPS) of PLMN#B) selects and registers to PLMN#B's 5G SA (according to existing specifications), PLMN#B can send a reject message with a well-known reject cause code (e.g., reject cause code #27 or #15 in the REGISTRATION REJECT message in 5G) to prevent the inbound roamer / UE from registering to its 5G SSA.

[0087] However, these approaches do not prevent registration requests on restricted RATs, but rather place a burden on the network in handling these requests.

[0088] As the number of subscribers for national inbound roaming is higher compared to international inbound roaming, a scheme relying on sending a reject cause code will result in higher signaling load on the 5GS RAT of the mobile network.

[0089] Therefore, an improved solution for preventing a UE from sending a 5G registration towards the NAS without impacting the AS is desirable.

[0090] Furthermore, during drive testing of a mobile network, it has been observed that relying on rejection of a registration request can result in downtime for the UE. Tests have shown that a UE trying to access a restricted RAT (e.g. 5G SA) stops serving in most cases for at least 22s and in other cases can take up to 12 minutes to regain 4G service.

[0091] Additionally, the reject message can be sent without integrity protection and can be open to abuse. For example, a malicious actor can set up a fake network mimicking a PLMN to lure UEs to try to register. The fake network can then send a reject message to the UE (without integrity protection) indicating that the UE is not to use the PLMN for an extended period of time (e.g. next 24 hours). This can prevent a legitimate UE from accessing a legitimate PLMN (in a denial of service attack).

[0092] The proposed method aims to improve the existing behavior such that the UE is configured to connect to the NAS via the allowed RAT without impacting the AS. The proposed method can prevent instances of inbound roamers from sending a registration request message and thus reduce the signaling storm that can occur in the 5GS due to UEs trying to connect to the 5GS while exploiting national roaming. Furthermore, the proposed method can help prevent inbound roamers from stopping serving for a long period of time due to a rejected registration attempt.

[0093] In the proposed method, the core network (which in some examples can be a 2G GPRS core, a 4G EPS core or a 5GS core) sends an indication of a restricted RAT (which can be in the form of forbidden RAT IE(s)) to the UE. The indication can be sent when the UE successfully attaches or registers to the corresponding 2G, 4G or 5G system (on the allowed RAT). For example, when a UE successfully attaches to a mobile network via a 4G RAT, the mobile network can indicate to the UE that the 5G RAT is restricted. Therefore, the UE can not try to connect to the mobile network via 5G (which would result in a scenario where a reject message is sent, as described above).

[0094] While certain specific examples have been described above in relation to UEs being restricted via 4G and 5G connections, the proposed approach is not limited to examples where these particular technologies are allowed / restricted, but can be used more broadly. In other examples, the proposed approach can be used to restrict access via 6G.

[0095] While some of the examples described above relate to national roaming, this is not the only possible scenario in which the proposed approach is applicable. For example, in other scenarios, a mobile network can restrict a particular UE from using one or more particular RATs in response to UE behavior. The mobile network can measure the energy usage rate for each UE. If a particular UE uses too much energy, the mobile network can restrict the UE from using a RAT.

[0096] In some examples, a mobile network can restrict a group of UEs, such as national roamers. In other examples, a mobile network can restrict one of its own subscribers from a particular RAT (e.g., in response to UE behavior, as discussed above).

[0097] In some examples, a UE can be restricted from accessing one or more particular RATs in all coverage areas (country-wide). In other examples, the restriction can be geographically limited. For example, 5G can be restricted in urban areas but allowed in rural areas. In another example, a UE can be restricted from accessing another network provider’s 5G network via national roaming in areas where the user’s home network has 5G coverage, but the UE can be allowed to access the 5G RAT of another (nationally roaming) network in areas where the user’s home network does not have 5G coverage.

[0098] In yet another example, the areas where a particular RAT is restricted can depend on energy consumption in the respective areas. The areas where a RAT is restricted can be dynamically set.

[0099] 3GPP TS 24.301 describes ATTACH ACCEPT and TRACKING AREA UPDATE ACCEPT messages, which can be modified in some example approaches. Specific examples of the proposed solution are described in detail below in the context of 3GPP TS 24.301. Material from this technical specification is included for background and to provide context for the present invention. No claim of protection is made to the material included in the prior art specification (3GPP TS 24.301 V18.6.0). Numbering from 3GPP TS 24.301 is preserved for ease of reference. References to clauses are in relation to 3GPP TS 24.301, unless otherwise specified.

[0100] 5.3.x Limitations on the utilization of radio access technologies In order to efficiently use network resources, network operators can regulate certain subscribers from accessing specific radio access technologies (RATs) (see 3GPP TS 22.011 [1A]). For this purpose, the MME can transmit a list of restricted RAT(s) associated with the registered PLMN to the UE via the ATTACH ACCEPT message and the TRACKING AREA UPDATE ACCEPT message (see clause 5.5.1.2 and clause 5.5.3.2). If any RAT(s) associated with the registered PLMN is restricted, the UE shall not use it for cell selection and cell reselection within the registered PLMN if the applicability information within the restricted RAT(s) IE specifies that "restricted RAT(s) apply within the registered PLMN" (3GPP TS 36.304

[21] ). In addition, the UE shall not use the restricted RAT(s) for cell selection and cell reselection (3GPP TS 36.304) until the current TAI is not in the list of TAIs if the applicability information within the restricted RAT(s) IE specifies that "restricted RAT(s) apply to any tracking area within the list of TAIs of the registered PLMN".

[0101] 5.5.1.2.4 Attach accepted by the network The MME can include a list of restricted RAT(s) associated with the registered PLMN in the ATTACH ACCEPT message. If the list is provided by the network, the UE shall store the list and replace the stored list each time an ATTCH ACCEPT message is received. If the ATTACH ACCEPT message does not contain the list, the UE shall delete the stored list. The UE shall provide the stored list to the AS for cell selection and cell reselection according to 3GPP TS 36.304.

[0102] 5.5.3.2.4 Normal and periodic tracking area update procedures accepted by the network The MME can include in the TRACKING AREA UPDATE ACCEPT message a list of restricted RAT(s) associated with the registered PLMN. The UE shall store the list as provided by the network and replace the stored list each time a TRACKING AREA UPDATE ACCEPT message is received. If the TRACKING AREA UPDATE ACCEPT message does not contain a list, the UE shall delete the stored list. The UE shall provide the stored list to the AS for cell selection and cell reselection purposes according to 3GPP TS 36.304.

[0103] 8.2.1.1 Message definition This message is sent by the network to the UE to indicate that the corresponding attach request has been accepted. See table 8.2.1.1.

[0104] Message type: ATTACH ACCEPT Significance: Double Direction: Network to UE Table 8.2.1.1: ATTACH ACCEPT message content

[0105] 8.2.1.29 Restricted RAT(s) This IE is included to indicate the restricted RAT(s) to be applied within the RPLMN.

[0106] 8.2.26.1 Message definition In response to a tracking area update request message, this message is sent by the network to the UE to provide the UE with EPS mobility management related data. See table 8.2.26.1.

[0107] Message type: TRACKING AREA UPDATE ACCEPT Significance: Double Direction: Network to UE Table 8.2.26.1: TRACKING AREA UPDATE ACCEPT message content

[0108] 8.2.26.34 Restricted RAT(s) This IE is included to indicate the restricted RAT(s) to be applied within the RPLMN.

[0109] 9.9.3.3x Restricted RAT(s) The purpose of the Restricted RAT(s) information element is for the network to convey a list of "Restricted RAT(s)" to the UE.

[0110] The Restricted RAT(s) information element is encoded as follows.

[0111] Restricted RAT(s) is a type 4 information element.

[0112]

[0113] 9.9.3.3x.1 Restricted RAT(s) information element Applicability (octet 3) Bit 2 1 0 0 Restricted RAT(s) apply within the registered PLMN 0 1 Restricted RAT(s) apply to any tracking area within the list of TAIs of the registered PLMN.

[0114] If received by the UE, all other values are not used and shall be interpreted as "Restricted RAT(s) apply within the registered PLMN".

[0115] Bits 3 to 8 of octet 3 are spare and shall all be coded as 0.

[0116] GERAN (octet 4, bit 1) Bit 1 0 GERAN is not restricted 1 GERAN is restricted E-UTRAN (octet 4, bit 2) Bit 2 0 E-UTRAN is not restricted 1 E-UTRAN is restricted E-UTRAN in NB-S1 mode (octet 4, bit 3) Bit 3 0 E-UTRAN in NB-S1 mode is not restricted E-UTRAN in WB-S1 mode (octet 4, bit 4) Bit 4 0 E-UTRAN in WB-S1 mode is not restricted 1 E-UTRAN in WB-S1 mode is restricted NG-RAN (octet 4, bit 5) Bit 5 0 NG-RAN is not restricted 1 NG-RAN is restricted Satellite NG-RAN (octet 4, bit 6) Bit 6 0 Satellite NG-RAN is not restricted 1 Satellite NG-RAN is restricted Satellite E-UTRAN in WB-S1 mode (octet 4, bit 7) Bit 7 0 Satellite E-UTRAN in WB-S1 mode is not restricted Satellite E-UTRAN in SB-S1 mode (octet 4, bit 8) Bit 8 0 Satellite E-UTRAN in SB-S1 mode is not restricted.

[0117] Figure 2 An example method of configuring radio access technology, RAT, utilization for a user equipment, UE, registering to a mobile network is illustrated. The method comprises transmitting 201, from a core network entity to the UE, an indication comprising one or more RATs restricted for the UE, wherein upon the indication taking effect, reception of the indication causes the UE to refrain from registration attempts on the one or more restricted RATs.

[0118] Figure 3 A user equipment, UE, 300 configured to perform the methods described above is illustrated. The UE 300 comprises a non-access stratum 301, NAS, and an access stratum 302.

[0119] Figure 4 A network entity 400 (e.g. a core network entity such as a mobility management entity) configured to perform the methods described above is illustrated. The network entity comprises a non-access stratum 401, NAS, and an access stratum 402.

[0120] Any of the methods described herein can be implemented as a computer program. The computer program can be configured to control a server (e.g., a network entity / node) and / or a UE to perform the described methods. A server (e.g., a network entity / node) of a mobile network and / or a UE configured to operate according to the described methods can also be provided. For example, the server can comprise a processor and at least one communication interface, in particular comprising one or both of a transmitter and a receiver. A UE configured to operate according to the described methods can also be provided. The UE can likewise comprise a processor and at least one communication interface, in particular comprising one or both of a transmitter and a receiver.

[0121] Although specific embodiments have been described, one skilled in the art will appreciate that various modifications and variations are possible. For example, although the disclosure is described in relation to existing network architectures and messages specific to existing network protocols, it will be appreciated that changes to the architecture, protocols and / or nomenclature are possible, but the proposed methods can still apply in that case. Also, combinations of any of the specific features shown with reference to one embodiment or with reference to multiple embodiments are provided, even if the combination is not explicitly detailed herein.

[0122] A base station (BS) generally refers to a fixed station that performs communication with a UE and / or another BS and exchanges various types of data and control information with the UE and the other BS. Depending on the protocol, standard, context, or technology, the BS can be referred to as an advanced base station (ABS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a NodeB (NB), an eNode B (eNB), a gNode B (gNB), a transmit and receive point (TRP), a processing server (PS), or some other suitable terminology. In some examples, a base station can include two or more transceivers that can or can not be collocated. Each transceiver can communicate on a same or different carrier frequency.

[0123] Where the present application refers to a server or network entity, for example, this can in redundancy actually be a pair of servers or network entities (primary and failover).

[0124] In the present application, a node refers to a fixed point capable of transmitting / receiving radio signals through communication with a UE. Various types of base stations, such as those described above, can be used as a node, regardless of the term used. In other examples, a node can be a relay, a repeater, or the like.

[0125] In the disclosure, a UE can be a fixed or mobile device. Examples of the UE include various devices that transmit and receive user data and / or various types of control information to and from a base station. The UE can be referred to as terminal equipment (TE), a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), a wireless modem, a handheld device, or the like.

[0126] Although the above methods are described with respect to 4G / LTE networks, the methods, techniques, apparatuses, and systems can be applicable to a variety of wireless multiple access systems. Examples of the multiple access systems include CDMA, FDMA, TDMA, OFDMA, SC-FDMA, and MC-FDMA. CDMA can be embodied through radio technology such as UTRA or CDMA2000. TDMA can be embodied through radio technology such as GSM, GPRS, or EDGE. OFDMA can be embodied through radio technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or E-UTRA. UTRA is a part of UMTS. 3GPP LTE is a part of E-UMTS using E-UTRA. 3GPP LTE adopts OFDMA in DL and SC-FDMA in UL. LTE-A is an evolved version of 3GPP LTE. 3GPP NR employs OFDMA for both downlink and uplink and can operate in both FDD and TDD. For convenience of description, it is assumed that the disclosure is applicable to 3GPP LTE. However, technical features of the disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to 3GPP LTE, aspects of the disclosure that are not specific to 3GPP LTE are applicable to other mobile communication systems. In addition, technical features of the disclosure can be applicable to future iterations of multiple access systems defined in 3GPP standards, such as (but not limited to) 5G / NR and 6G.

[0127] In the present disclosure, a cell refers to a geographical area to which one or more nodes provide communication services. Accordingly, in the present disclosure, communicating with a particular cell can mean communicating with a gNB or node that provides communication services to the particular cell. Further, a channel state / quality of a particular cell refers to a channel state / quality of a channel or communication link formed between a UE and a gNB or node that provides communication services to the particular cell. The UE can measure a DL channel state received from a particular node using cell-specific reference signal (CRS) and / or channel state information reference signal (CSI-RS) transmitted on a CRS resource and a CSI-RS resource, respectively, which is allocated to the particular node by an antenna port(s) of the particular node. Meanwhile, the 3GPP system uses the concept of a cell in order to manage radio resources, and a cell associated with a radio resource is distinguished from a cell of a geographical area.

[0128] Examples can be implemented on any suitable data processing equipment such as personal computers, laptops, mobile phones, servers, virtual machines, and so on. The above description of systems and methods has been simplified for purposes of discussion and is intended to provide specific examples to illustrate the application. Different types of systems and methods can be used, as will be appreciated by those skilled in the art. It should be appreciated that the boundaries between logic blocks are merely illustrative and alternative embodiments can merge logic blocks or elements, or can split the functionality of a logic block or element across multiple logic blocks or elements.

[0129] It should be appreciated that the above-mentioned functions can be implemented as one or more corresponding modules as hardware and / or software. For example, the above-mentioned functions can be implemented as one or more software components for execution by a processor of the system. Alternatively, the above-mentioned functions can be implemented as hardware, such as on one or more FPGAs, and / or one or more ASICs, and / or one or more DSPs, and / or other hardware arrangements. Each of the method steps implemented in the flowcharts contained herein or as described above can be implemented by a corresponding module. Further, multiple method steps implemented in the flowcharts contained herein or as described above can be implemented together by a single module.

[0130] Examples can be implemented by computer software or "computer programs", or "programs". Storage media and transmission media are also provided carrying computer programs. A computer program can include one or more instructions or codes, when executed by a computer, cause the methods described to be performed. A computer program can be a sequence of instructions designed for execution on a computer system, and can include subroutines, functions, procedures, modules, object methods, object implementations, executable applications, applets, servlets, source code, object code, shared libraries, dynamic linked libraries, and / or other sequences of instructions designed for execution on a computer system. A storage media can be a magnetic disk (such as a hard disk drive or floppy disk), an optical disk (such as a CD-ROM, DVD-ROM or Blu-ray disk), or a memory (such as a ROM, RAM, EEPROM, EPROM, flash memory or portable / removable memory device), etc. A transmission media can be a communication signal, a data broadcast, a communication link between two or more computers, etc.

[0131] Unless otherwise stated, each feature disclosed in the specification is a separate disclosure that can be replaced by alternative features disclosed in the specification. Thus, unless otherwise stated, each feature disclosed is only one example of a generic series of equivalent or similar features.

[0132] As used in this document, including in the claims, the singular forms "a," "an," and "the" are to be construed as including the plural forms as well, unless the context indicates otherwise. For example, the use of the singular forms "a" or "an" or "the" (such as a UE, a node, a network entity, a RAN entity, or a cell) herein, including in the claims, is not intended to exclude the plural forms (e.g., one or more UEs, one or more nodes, one or more network entities, one or more RAN entities, or one or more cells). Throughout the specification and claims, the words "comprise," "contain," "have," and "include," and variations thereof (e.g., "comprising," "containing," "having" or "including") mean "including but not limited to," and are not intended to (and do not) exclude other components.

[0133] The use of any and all examples, or exemplary language ("for instance", "such as", "for example" and like language) provided herein is intended merely to better illuminate the application and does not indicate a limitation on the scope of the application unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the application.

[0134] Any of the steps described in this specification can be performed in any order or simultaneously, unless otherwise specified or required by the context. Furthermore, where steps are described as being performed after other steps, this does not preclude intermediate steps being performed.

[0135] All aspects and / or features of the present specification can be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. As described herein, there can be particular combinations of aspects where further benefit is derived, such as aspects of determining a set of compensation parameters and applying the set of compensation parameters to a measurement result. In particular, preferred features of the application are applicable to all aspects of the application and can be used in any combination. Likewise, features described in non-essential combinations can be used separately (not in combination).

[0136] Methods of manufacturing and / or operating any of the apparatuses disclosed herein are also provided. The method can include the step of providing each of the disclosed features and / or configuring or using the respective features for the declared functionality thereof.

Claims

1. A method for configuring radio access technology (RAT) utilization for a user equipment (UE) registered to a mobile network, the method comprising: An indication is transmitted from a mobile network to a UE including one or more RATs restricted for the UE, wherein receipt of the indication causes the UE to suppress registration attempts on the one or more restricted RATs when the indication is in effect.

2. The method of claim 1, wherein the indication further comprises one or more RATs allowed for the UE.

3. The method of claim 1 or claim 2, wherein the indication is transmitted during a UE-initiated mobility specific procedure, wherein the indication is transmitted via a non-access stratum (NAS) functional layer between the UE and the core network.

4. The method of claim 3, further comprising: The indication is delivered from the NAS function layer of the UE to the access stratum AS function layer of the UE.

5. A method as claimed in any preceding claim, wherein the indication is transmitted with a secure message.

6. A method according to any preceding claim, wherein: The indication remains in effect until it is deleted or replaced by another indication of a restricted RAT; and / or The instruction includes an expiration time, and wherein the instruction is effective until it expires.

7. The method according to any preceding claim, further comprising: monitoring one or more reference signals corresponding to one or more cells operating via the unrestricted one or more RATs and evaluating cell selection and / or cell reselection criteria on the one or more reference signals; as well as Monitoring of reference signals corresponding to cells operating via the one or more restricted RATs is suppressed.

8. The method according to any preceding claim, further comprising: The one or more RATs restricted for the UE are stored on a subscriber identity module SIM of the UE.

9. A method as claimed in any preceding claim, wherein: the instruction is effective for the entire mobile network; or The indication further includes one or more regions in which the indication is effective.

10. The method of claim 9, wherein the one or more regions include one or more of the following: one or more location areas, One or more routing areas, One or more cells, One or more tracking areas, One or more geographic regions, One or more registration areas, and One or more network regions.

11. The method of claim 9 or claim 10, further comprising: It is determined that the UE is located in one of the one or more areas in which the indication is valid.

12. The method of any preceding claim, further comprising: performing data analysis on the UE via the RAT on which the UE is registered; identifying, from the data analysis, an occurrence of an event, wherein the event causes the mobile network to limit utilization of a RAT on which the UE is registered; as well as An indication is transmitted from a core network entity to the UE that the RATs on which the UE is registered are restricted for the UE.

13. A user equipment (UE) configured to perform the method according to any one of claims 1 to 11.

14. A server configured to execute the method according to any one of claims 1 to 3, 5, 6, 9, 10 or 12.

15. A computer program comprising instructions which, when executed on a processor, cause the processor to perform the method of any one of claims 1 to 12.

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