Applying network access restrictions for particular user equipment

Abstract

An apparatus and method, the method comprising: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or current connection to a public land mobile network PLMN using a first radio access technology type is restricted for the apparatus, the message further comprising information regarding restrictions for the apparatus for other RAT types supported by the PLMN. Determining from the indication and information whether to request access to the PLMN using a RAT that is not indicated as being restricted or whether to request access to a different PLMN; and requesting the access.

Description

APPLYING NETWORK ACCESS RESTRICTIONS FOR PARTICULAR USER EQUIPMENTTECHNOLOGICAL FIELD

[0001] Various example embodiments relate to wireless communication networks and to applying user specific access restrictions to a network.BACKGROUND

[0002] National roaming services are required to provide seamless connectivity for mobile user equipment, particularly in areas where the primary network operator lacks coverage. Networks may provide access to the network using multiple different Radio Access Technologies RAT, such as 4G and 5G.BRIEF SUMMARY

[0003] The scope of protection sought for various example embodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0004] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0005] An aspect provides a mechanism for indicating to an apparatus such as a mobile user equipment where a requested or current RAT used for connection to a PLMN is not or is no longer appropriate. Information is also supplied to the apparatus regarding restrictions for other RAT types supported by the PLMN. This allows the apparatus to determine whether to request access to a different PLMN or to use a different RAT to access the existing PLMN. In this way dynamic RAT restrictions can be applied to specific UEs such as roaming UEs within for example a VPLMN visited PLMN.

[0006] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the apparatus at least to perform: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0007] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0008] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0009] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program which when executed by a processor on an apparatus is operable to cause said apparatus to perform a method as described above.

[0010] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0011] Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.BRIEF DESCRIPTION

[0012] Some example embodiments will now be described with reference to the accompanying drawings in which:

[0013] FIG. 1 illustrates an example embodiment of signalling between a user equipment and network;

[0014] Fig.2 schematically illustrates a user equipment and network nodes according to an embodiment; and

[0015] Fig. 3 shows a flow diagram schematically illustrating steps of a method performed at a network control node according to an embodiment; and

[0016] Fig. 4 shows a flow diagram schematically illustrating steps of a method performed at a user equipment according to an embodiment.DETAILED DESCRIPTION

[0017] Before discussing the example embodiments in any more detail, first an overview will be provided.

[0018] Currently the only existing mechanisms to limit the UE's utilization of certain RAT employed by the network operator involves rejecting the UE's attach / TAU tracking area update request or a registration request with certain cause codes, such as CC#15 or CC#27. Which are defined as follows:• Cause #15 - No suitable cells in tracking area o This 5GMM cause is sent to the UE if it requests service, or if the network initiates a deregistration request, in a tracking area where the UE, by subscription, is not allowed to operate, but when it should find another allowed tracking area in the same PLMN or an equivalent PLMN or the same SNPN or an equivalent SNPN.• Cause #27 - N1 mode not allowed o This 5GMM cause is sent to the UE if it requests service, or if the network initiates a deregistration request, in a PLMN or SNPN where the UE by subscription or operator policy, is not allowed to operate in N1 mode.

[0019] However, these cause codes simply indicate that the public land mobile network PLMN is restricted for the UE and there is no possibility of indication that the request has been rejected due to the RAT being restricted. This results in: a) increased signaling loads within the network; b) service outage until the UE selects another RAT; andc) UE keeping re-attempting on the same PLMN / RAT upon the UE re-enabling the corresponding RAT.

[0020] Embodiments seek to enhance the ability to apply dynamic RAT restrictions to specific UEs such as roaming UEs within a VPLMN visited PLMN. Some RAT restrictions are envisaged and a partial RAT restriction list may be sent on registration accept or UCU (UE configuration update) but this does not include the RAT that a UE is currently connected to or one that it is requesting and there is no mechanism for rejecting a UE from a RAT that it is connected to, where circumstances change and this becomes desirable by the network / operator. Furthermore, if a connection request is refused no information regarding whether this is due to a RAT restriction is provided, i.e. the RAT registration reject command does not contain information regarding RAT restriction, if applicable.

[0021] Embodiments provide information as to whether a rejection for connection or a disconnection command is due to a RAT restriction. Additional information regarding other RATs supported by the network node and whether they are restricted or not for the user equipment may also be provided. Furthermore, time period information may be provided indicating a time period during which the one or more RAT restrictions may be applied.

[0022] PLMN selection and roaming

[0023] The Mobile Station (MS) or user equipment UE normally operates on its home PLMN (HPLMN) or equivalent home PLMN (EHPLMN). However, a visited PLMN (VPLMN) may be selected, e.g., if the MS loses coverage. There are two modes for PLMN selection:I) Automatic mode: This mode utilizes a list of PLMN / access technology combinations in priority order. The highest priority PLMN / access technology combination which is available and allowable is selected. ii) Manual mode: In this case the MS indicates to the user which PLMNs are available. Only when the user makes a manual selection the MS tries to obtain normal service on the VPLMN.

[0024] To inhibit repeated attempts to have roaming service on a not allowed area (i.e. Local Area (LA) or Tracking Area (TA)), when the MS is informed that an area is forbidden, the LA or TA is added to a list of "forbidden or restricted location areas for roaming" or "forbidden tracking areas for roaming" respectively which is stored in the MS. These lists, if existing, are deleted when the MS is switched off or when the SIM is removed, and periodically (with period in the range 12 to 24 hours). LA area restrictions may always be valid for complete location areas independent of possible subdivision into GPRS routing areas. The structure of the routing area identifier (see 3GPP TS 23.003 [22A]) supports area restriction on LA basis.

[0025] In order to indicate / trigger the change of the PLMN / RAT due to potential restrictions for an operator, the main operations and messages are the following:• UE Registration (initial / MRU mobility registration update) procedure, and,• UE configuration update UCU.

[0026] Although these messages may provide some information for future connections, there is no provision for restricting a RAT in which the UE is currently connected.

[0027] This can present problems, for example, let us consider a scenario where in a specific area a PLMN / RAT had initially a small number of home subscriber UEs connected, i.e. , low load / congestion for that PLMN and RAT. Hence, it did not restrict the incoming roamers for that PLMN / RAT. After some time when the number of home subscribers increases, the operator may want to restrict the roaming UEs which are already connected to the PLMN / RAT. As per above arrangement, the network is not capable of doing this as the network cannot restrict the UE for a RAT in which the UE is currently connected (i.e., NG-RAN). In effect the network cannot deregister a UE and although the network may reject a Registration Request (by the UE) it can only do so on a PLMN basis with no indication that it is specific to a particular RAT.

[0028] Additionally, when the UE receives a REJECT message from the network with such a condition code CC#15 or CC#27, it starts a timer T3540 (10 seconds). Upon expiration of this timer, the UE is allowed to keep re-trying to connect to the same PLMN / RAT which has been restricted even though it has no information that the PLMN / RAT is available again. This increases signaling from the UE to the network, i.e., the UE trying to attach / register via a RAT that may still be restricted, since it is not intended to have a per RAT restriction granularity.

[0029] Embodiments described below seek to address the above and describe how to handle certain different RAT restriction scenarios:

[0030] Embodiments seek to provide increased granularity in restrictions to UEs attaching and those already connected to the network by providing a means of applying restrictions on a RAT basis to specific UEs such as roaming UEs. In particular, embodiments seek to be able to inhibit selected UEs that are currently connected via a RAT or seek to connect via a RAT from continuing to use that RAT for accessing the network, where it is determined by the network that such restrictions are desirable.

[0031] Scenario 1 - Entire / Complete RAT restriction: In this scenario network seeks to impose RAT restriction on all the RATs, that may be all existing RATs or all those supported by the UE. This scenario may arise during initial registration (network shall use REGISTRATION REJECT) or when UE is already registered (network shall use DEREGISTRATION REQUEST).

[0032] Fig. 1 shows signaling that may occur when a UE seeks to connect to a network using a particular RAT and that RAT and possibly other RATs, in some cases all RATs (as for scenario 1 above) that are currently restricted for the UE in that location.

[0033] In a first step 1 , the UE 410 is in IDLE mode and sends an initial registration request message to the network via RAT_1 . This signaling message is sent to a network node 430 which provides access to a PLMN under which different types of RATs such as 3G, 4G, 5G and 6G are available and this request isthen sent to the network control node 420. If the network control node 420 (e.g., the MME, AMF or 6GMM) determines at step 2 that RAT_1 is restricted for the UE, then the network can send a REGISTRATION REJECT message with a cause value at step 3. This cause value may indicate that the RAT is restricted at the current location for the UE and may be sent together with the RAT Utilization Control information (e.g., RAT restriction list). This list may contain information regarding other RATs that are currently restricted for the UE at this location. Due to the association of the rejection message and RAT_1, this serves as an indication to the UE that the network does not allow the RAT the UE would like to use, i.e., RAT_1 . Furthermore, there is an indication in the registration reject message of what other RATs are restricted or not restricted. Hence, the UE may decide at step 4 to either change to a different RAT (if one is available) or change to another PLMN (if available). The UE can indicate this decision to the lower layer or access layer of the UE which then can select appropriate cell or access node of the RAT which is not restricted for registration.

[0034] The Network control node 420 (e.g.., MME mobile management entity, AMF access and mobility function or 6GMM mobility management) can also send an indication of a time period (e.g., TRAT) together with the REJECT message and the associated RAT at step 3 to indicate to the UE that the RAT restriction is applicable for that time period TRAT. The UE 10 may then start a timer for that time period TRAT and only when the timer has expired does the UE try to re-enable the restricted PLMN / RAT, by removing it from the restricted list.

[0035] The lower signaling diagram of Fig, 1 shows signaling that occurs when the UE 410 is already registered in the PLMN on a RAT (e.g., RAT-X) and the network wants to restrict the RAT for the UE (this is up to operator decision and can happen due to congestion, load, or priority treatment, etc.), the network can handle it in following way:

[0036] If the network wants to impose RAT restriction on entire / all RATs: (those supported by UE or all existing RATs of the PLMN) Then at step 3 it transmits a network-initiated Deregistration message to the UE with RAT Utilization Control information indicating "total / entire RAT restriction”. This is an indication for the UE not to retry on the specified restricted RATs again and to change the PLMN. The network (i.e., MME, AMF or 6GMM) can also send a time indication (e.g. TRAT) to indicate to the UE that the restriction is applicable for a TRAT time. The UE may initiate a timer with TRAT and after the completion of the timer UE may delete the PLMN / RAT information from the forbidden list and in some cases may store it with highest priority in the list of PLMNs for selection and try to re-connect to the PLMN / RAT. TRAT can be a list of timers specific to each RAT. Or, alternatively, TRAT can be a common timer for the RAT restriction of the PLMN, when all RATs are restricted.

[0037] The UE may send time information TRAT in all the messages where RAT restriction info is conveyed (e.g., ACCEPT, UCU, REJECT, De-reg, etc.). It may communicate this in two ways:

[0038] If different there are different time periods for each RAT, then the time period may be sent along with the RAT restriction information (RAT restriction IE can be enhanced to include the time information). In this case there will be a TRAT list will be sent.

[0039] Alternatively, TRAT may also represent single time period is associated with the whole PLMN level RAT restriction, where all the RATs are restricted for the UE, then it may be communicated separately.

[0040] When the UE receives RAT restrictions, it stores the one or more restricted RATs with associated PLMN in a restricted list and does not consider the one or more restricted RATs for selection. The UE may put the PLMN into a forbidden list when it determines all RATs are restricted for the PLMN, otherwise only that particular RAT associated with the PLMN is restricted and stored in the restricted list. If the UE wants to re-connect to that restricted RAT and associated PLMN, it will start a timer for the time period indicated in TRAT and wait till it lapse (e.g., TRAT value becomes zero) and then removes the RAT and associated PLMN from restricted list and put it in the selection list with priority in order to consider for selection.

[0041] The lower signaling diagram also illustrates a further scenario, scenario 2 - partial RAT restriction including current RAT: Operator / Network wants / needs to apply RAT restriction on UE's current RAT (e.g., E-UTRAN) but allow UE on at least one other RAT.• When network control node determines that it wants to impose RAT restriction on current RAT in step 2 of the lower signaling diagram of Fig. 1 :Network control node 420 generates and transmits at step 3 a UE Configuration Update Command (UCU) message with RAT Utilization Control information indicating "partial RAT restriction including current RAT”.

[0042] In such case UE cannot continue to use current RAT but can try to Ret connect on other nonrestricted RATs in the same PLMN.

[0043] This is an indication for the UE to initiate Mobility registration update procedure (MRU) at step 4 to connect using a different RAT within the same PLMN. UE can indicate this to the lower layers which then select cell of a non-restricted RAT transmits the registration request. The network 420 (i.e., MME, AMF or 6GMM) can also send a time value (e.g. TRAT) to indicate the UE that the restriction is applicable for a time period TRAT, or until an indicated time or a range of time.

[0044] Alternatively, the UE may choose to re-register to a new PLMN.

[0045] In some alternative example scenarios, the network can impose a partial RAT restriction excluding current RAT. In such scenario, the Operator / Network would want to apply partial RAT restriction on UE other than the current RAT (e.g., if UE is already registered to the network and connected to RAT_X, network can impose RAT restriction on all other available RATs than RAT_X) but allow UE on other RATs.- In such case UE can continue with the current RAT / PLMN but may store information regarding other RATs that are restricted for future use.

[0046] The steps of Fig. 1 are set out below in more detail:

[0047] Step 1 : For the case when the UE 410 is in IDLE mode, initiating an initial registration request to the network via RAT_X.

[0048] Step 2: The network, i.e., AMF / 6GMM or MME 420, based on operator decision indicates to the UE the restriction for RAT_X or for "all the RATs” for the UE.

[0049] Step 3: The network can send a REGISTRATION REJECT message with cause value #15 (No suitable cells in tracking area), #13 (Roaming not allowed in this tracking area), #11 (PLMN not allowed) or a new CC#X (e.g., indicating RAT is restricted for UE in this location) along with the RAT Utilization Control information (e.g., RAT restriction list) which may mention "entire / all RATs are restricted for the UE”. This is an indication to the UE that the network has restricted all the RATs the UE would like to use, and UE may need to select a different PLMN. The network function also may send a time period or time indication or time range TRAT to indicate to the UE that the restriction is applicable for a time period and after this the UE may select the previously restricted RAT.

[0050] Alternatively, step 3 may involve the network sending a REGISTRATION REJECT message with cause value #15, #17, #13 or a new CC#X (e.g., indicating RAT is restricted for UE in this location) along with the RAT Utilization Control information (e.g., RAT restriction list) with mentioning "partial RATs restriction applied including the current RAT” with a "re-registration required” indication. This is an indication to the UE that the network has restricted the specific RAT the UE would like to use. The network function also may send a timer TRAT to indicate the UE that the restriction is applicable till TRAT time.

[0051] Step 4: Upon receiving the REGISTRATION REJECT message from the network, the UE may either change to a different RAT in case of partial RAT restriction or change to a different PLMN in case of all / entire RAT restriction or wait upon expiration of the timer TRAT to select again the restricted PLMN / RAT (if the network has sent the timer TRAT). The UE can indicate this information to the lower access layer to aid the cell selection / reselection process.

[0052] If the REGISTRATION REJECT message contains the RAT utilization control IE, the UE shall store in its memory the received RAT utilization control information and replace the previously stored one, if any, with the newly received RAT utilization control information. Otherwise, if the REGISTRATION REJECT message does not contain the RAT utilization control IE, the UE shall consider that the REGISTRATION REJECT is not due to RAT restriction.

[0053] Scenario- (b) as indicated in Fig. 1:

[0054] Step 1 : The UE 410 is already registered to the PLMN via RAT_X.

[0055] Step 2: The network, i.e., AMF / 6GMM or MME 420, based on operator decision indicates to the UE the restriction of a particular PLMN / RAT_X for the UE.

[0056] Step 3a: The network can send a DEREGISTRATION message along with the RAT Utilization Control information (e.g., RAT restriction list) indicating "all RATs are restricted for the UE”. The networkmay send this when it understands that the UE does not have any other RAT to connect with the PLMN. This is an indication to the UE that it needs to change the PLMN (if other PLMN is available).

[0057] Step 3b: The network can send a UE Configuration Update Command message along with the RAT Utilization Control information (e.g., RAT restriction list) with indication of partial RATs restriction applied including the current RAT”. This is an indication to the UE that it needs to change the RAT. UE then can initiate MRU procedure to change the RAT in the same PLMN.

[0058] The Network can also send a timer (e.g., TRAT) to indicate the UE that the restriction is applicable till TRAT time together with the RAT Utilization Control information. The UE might try to re-connect to the restricted PLMN / RAT upon expiration of the timer TRAT.

[0059] The RAT utilisation control information may be sent in a RAT utilisation control element, which may contain an indication of the type of RAT utilisation control, this may be: RAT restriction is not applied, partial RAT restriction is applied excluding the current RAT, partial RAT restriction is applied and includes the current RAT or entire RAT restriction is applied.

[0060] Step 4:If UE receives DEREGISTRATION message, it can try to try change the PLMN (if other PLMN is available). It can either do it manually or send to lower layers an indication to de-prioritize the current PLMN in the PLMN / RAT selection list.If UE receives UCU message, UE initiates MRU process and tries to change the RAT (if any other available from the RAT restriction list). It can either manually send to lower layers an indication to select another RAT in the same PLMN (if available).As another option, the UE might try to re-connect to the restricted RAT upon expiration of the timer TRAT.As an alternative option, UE may change to a different RAT of same PLMN or different PLMN and after time TRAT comes back to the previous PLMN / RAT.

[0061] In summary, the above embodiments for the RAT restriction feature allow the handling of partial RAT restriction and define what will be the behaviour when the network imposes partial RAT restriction on the current or a requested RAT of the UE (e.g., current RAT is restricted along with other RATs or current RAT is unrestricted but other RATs are restricted, or all RATs are restricted).

[0062] Fig. 2 shows a network control node / entity 420 which may be configured to perform the method steps shown in Fig. 3. The network control node 420 comprises at least one memory 422 which may store instructions executable by at least one processor 421 of the network node 420. The network control node 420 may comprise a transceiver 423 for transmission and reception of signals. The network control node may refer to at least one of the following non-limiting examples: an AMF, an MME or 6G MM.

[0063] Fig. 2 further shows a user equipment 410 configured to perform the method steps shown in Fig. 4. The user equipment 410 comprises at least one memory 412 which may store instructions executable by at least one processor 410 of the user equipment 410. The user equipment 410 may comprise a transceiver 413 for transmission and reception of radio signals. The user equipment 410 may comprise a timer 414. The user equipment refers to any mobile end or terminal device that may be capable of wireless communication. By way of example rather than limitation, user equipment UE may also be referred to as a communication device, a terminal device, a Mobile Station (MS). The user equipment may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a tablet, a wearable terminal device, a personal digital assistant (PDA), vehicle-mounted wireless terminal devices, smart devices etc.

[0064] Fig 3 shows a flow diagram schematically illustrating steps performed at a network control node according to an embodiment. At a first step S10 it is determined whether one or more of the RATs supported by the network are restricted for a set of user equipment in a certain location. A set of user equipment may just be a single user equipment, some user equipment or may be a particular group of user equipment such as roaming user equipment that are not on their home PLMN.

[0065] At step S20 the network control node determines one of the set of user equipment is currently accessing or is requesting access to the PLMN using one of the RATs that it has determined to be restricted. At step S30 the network control node generates a message with an indication that this RAT and in some cases other RATs are restricted for the user equipment. At step S40 it transmits a message to the user equipment.

[0066] In some cases, the network control node may determine a time period during which the restrictions are valid and may transmit this time period along with the indication of the restrictions to the user equipment. The message may be transmitted to the user equipment as a deregistration message or as a user equipment configuration update message. Alternatively, where the UE has requested access to the PLMN using a RAT that it is determined to be restricted it may be transmitted as a registration reject message.

[0067] Fig. 4 shows steps in a method performed at a user equipment according to an embodiment. In a first step S100 the user equipment receives a message from the network, the message contains an indication that the currently used RAT is restricted for the user equipment. It may contain further restriction indications indicating whether other RATs are also restricted for the user equipment, and it may contain time periods indicating the length of time that these restrictions are deemed to be valid. At step S110 the user equipment stores the received information and in some cases at step S 120 it may set one or more timers for the time period or time periods indicated in the message. At step D5 the user equipment determines if there is a RAT that is not restricted and if there is at step S130 the user equipment initiates an MRU to change from the current restricted RAT to a non-restricted RAT. At step D15 the userequipment determines whether the timer has expired for the previously used and restricted RAT and where it has it may at step S140 update the stored information and at step S150 initiate an MRU to change back to the previously used and restricted RAT. Where it updates the stored information then it may store the previously used RAT that is no longer restricted in a non-restricted list with a highest priority.

[0068] If at step D5 it is determined that there is not a RAT that is not restricted for the user equipment, the user equipment will at step S160 de-register from the current network. It will then determine at D25 if another PLMN is available and if it is it will register to the new PLMN. If it is not, then it will wait till one of the timers has expired at D35 and will register to the previously used PLMN using the RAT associated with the expired timer at step 180. It will also update the stored information in its memory to indicate that the RAT is no available at step S190.

[0069] If at D25 it is determined that there is not another PLMN that is available, it will wait for expiry of one of the timers at D35 and then register to the previous PLMN using the available RAT S180 and update the stored information in its memory at step S190.

[0070] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the apparatus at least to perform: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0071] An aspect provides a mechanism for indicating to an apparatus such as a mobile user equipment where a requested or current RAT used for connection to a PLMN is not or is no longer appropriate. Information is also supplied to the apparatus regarding restrictions for other RAT types supported by the PLMN. This allows the apparatus to determine whether to request access to a different PLMN or to use a different RAT to access the existing PLMN. In this way dynamic RAT restrictions can be applied to specific UEs such as roaming UEs within for example a VPLMN visited PLMN.

[0072] In some embodiments, said message comprises one of: a registration reject, deregistration or user equipment UE configuration update message.

[0073] In some example embodiments, said apparatus is further caused to perform receiving at least one indication indicative of at least one time period during which at least one of said RATs that is indicated as restricted is restricted; updating at least one timer associated with said at least one of said restricted RATsbased on a respective one of said at least one time period; and inhibiting requesting connection to said PLMN using said at least one of said restricted RATs during said time period.

[0074] The indication that the RAT is restricted may be sent with an indication of a time period during which this restriction is to be considered valid. During this time period the apparatus will inhibit or disable the generation and transmission of requests to connect to the PLMN using that RAT.

[0075] In some embodiments, the apparatus is further caused to perform storing information regarding RATs that are restricted for said apparatus for said PLMN and inhibiting or disabling requesting connection to said PLMN using a RAT from said list.

[0076] In some cases, the information received regarding RATs that are restricted or not restricted may be stored in the memory of the apparatus. In some cases, this may be in the form of a list of restricted RATs and / or a list of non-restricted RATs.

[0077] In some example embodiments, said apparatus is further caused to perform updating said information for RAT of said RATs that are restricted on expiry of the at least one timer which is associated with the RAT.

[0078] Where the information regarding the restriction or otherwise of the RATs is stored on the apparatus and is time dependent then this information may be updated as time periods indicating the validity of the restrictions expire. This may be determined using a timer that has been set for that time period expiring.

[0079] In some example embodiments, said RATs that are restricted comprises a preferred RAT, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: on expiry of said timer associated with said preferred RAT requesting connection to said PLMN using said preferred RAT.

[0080] A restricted RAT may be a preferred RAT and in such a case, on expiry of the timer the apparatus will request connection to the PLMN using the preferred RAT. In some cases, the preferred RAT is the first RAT, that is the RAT of the previous connection that the apparatus was connected via when it received the information that this RAT is now restricted or it may be a RAT that the apparatus had request a connection to the PLMN with.

[0081] In some example embodiments, said indication indicative of said at least one time period comprises an indication indicative of a time period during which said first RAT is restricted, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform storing said indication of said first RAT with a highest priority in a list of RATs available for said PLMN.

[0082] Where all of the RATs for a PLMN are indicated to be restricted there may be a single time period that is relevant for all the RATs and indeed for the restriction of the PLMN.

[0083] In some example embodiments, said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said current RAT restriction indicationand said RAT restriction information, said apparatus being caused to store said received RAT utilisation control information and discard previously stored RAT utilisation control information.

[0084] The RAT restrictions may be received as part of a RAT utilisation control information element and they may be stored by the apparatus following receipt and previous utilisation information elements for a particular RAT may be overwritten on receipt of an updated value.

[0085] In some example embodiments, said RAT utilisation control information element further comprises said indication of said time period.

[0086] In some example embodiments, said indication is received in one of a deregistration or a registration reject message, and said message comprises information indicating that all RATs supported by said PLMN are restricted for said apparatus, wherein the instructions, when executed by the at least one processor, further cause said apparatus to determine whether another different PMLN is available and where so request to access to said different PMLN.

[0087] It may be that not only a current or requested RAT is restricted or it may be that a subset of available RATs is restricted, or it may be that all RATs are restricted for this apparatus for a particular PLMN. In the latter case, the apparatus may determine whether another different PLMN is available and where so it may request access to this other PLMN.

[0088] In some example embodiments said indication is received in a user equipment configuration update message, wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: selecting a RAT supported by said PMLN and that is not indicated as being currently restricted for accessing said PMLN.

[0089] The indication may be received in a user configuration update message and in this case the user of the apparatus may select a RAT supported by the PLMN which is not currently being restricted and request access to the PLMN using this RAT. It may do this using a mobility registration update message.

[0090] In some example embodiments, the apparatus is a user equipment or mobile terminal.

[0091] According to various but not necessarily all example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the apparatus at least to perform: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0092] In some example embodiments, said message is transmitted in one of: a registration reject message when the user equipment is not registered; a deregistration message or user equipment configuration update message, when the user equipment is already registered.

[0093] In some example embodiments, said information regarding said restrictions comprises a list of restricted RATs.

[0094] In some example embodiments, said apparatus is further caused to perform: determining at least one time period during which at least one of said at least one RAT is restricted for said user equipment; and including an indication of said at least one time period in said message.

[0095] In some example embodiments, said message may comprise an indication of multiple time periods for multiple restricted RATs.

[0096] In some example embodiments, said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said RAT restriction indication and said RAT restriction information.

[0097] In some example embodiments, said RAT utilisation control information element further comprises said indication of said time period.

[0098] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: updating said indication that said one RAT is restricted on expiry of said at least one time period.

[0099] In some example embodiments, said updated RAT restriction indication comprises at least one updated time period.

[0100] In some example embodiments the apparatus is a network control node such as an AMF, MME or 6G-AMF.

[0101] The processor, memory, and example algorithms, encoded as instructions, program, or code, may be the means for providing or causing the performance of the operation.

[0102] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: means for receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; means for determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and means for sending, based on the determining, a request for said access based on he indication and information received.

[0103] The means may perform the optional features set out in relation to the apparatus mentioned above.

[0104] According to various, but not necessarily all example embodiments of the invention there is provided the apparatus, comprising: means for determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; means for determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; means for generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and means for transmitting said message to said at least one user equipment.

[0105] The means may perform the optional features set out in relation to the apparatus mentioned above.

[0106] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: circuitry configured to receive a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; circuitry configured to determine, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and circuitry configured to send, based on the determining, a request for said access based on the indication and information received.

[0107] The circuitry may be configured to perform the optional features set out in relation to the apparatus mentioned above.

[0108] According to various, but not necessarily all example embodiments of the invention there is provided the apparatus, comprising: circuitry configured to determine that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; means for determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; circuitry configured to generate a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and circuitry configured to transmit said message to said at least one user equipment.

[0109] The circuitry may be configured to perform the optional features set out in relation to the apparatus mentioned above.

[0110] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0111] In some embodiments, said message comprises one of: a registration reject, deregistration or user equipment UE configuration update message.

[0112] In some example embodiments, the method further comprises performing receiving at least one indication indicative of at least one time period during which at least one of said RATs that is indicated as restricted is restricted; updating at least one timer associated with said at least one of said restricted RATs based on a respective one of said at least one time period; and inhibiting requesting connection to said PLMN using said at least one of said restricted RATs during said time period.

[0113] The indication that the RAT is restricted may be sent with an indication of a time period during which this restriction is to be considered valid. During this time period the apparatus will inhibit or disable the generation and transmission of requests to connect to the PLMN using that RAT.

[0114] In some embodiments, the method further comprises storing information regarding RATs that are restricted for said apparatus for said PLMN and inhibiting or disabling requesting connection to said PLMN using a RAT from said list.

[0115] In some cases, the information received regarding RATs that are restricted or not restricted may be stored. In some cases, this may be in the form of a list of restricted RATs and / or a list of non-restricted RATs.

[0116] In some example embodiments, said method further comprises updating said information for RAT of said RATs that are restricted on expiry of the at least one timer which is associated with the RAT.

[0117] Where the information regarding the restriction or otherwise of the RATs is stored and is time dependent then this information may be updated as time periods indicating the validity of the restrictions expire. This may be determined using a timer that has been set for that time period expiring.

[0118] In some example embodiments, said RATs that are restricted comprises a preferred RAT, and the method further comprises, on expiry of said timer associated with said preferred RAT, requesting connection to said PLMN using said preferred RAT.

[0119] A restricted RAT may be a preferred RAT and in such a case, on expiry of the timer the method comprises requesting connection to the PLMN using the preferred RAT.

[0120] In some cases, the preferred RAT is the first RAT, that is the RAT of the previous connection that an apparatus was connected via when it received the information that this RAT is now restricted or it may be a RAT that the apparatus had request a connection to the PLMN with.

[0121] In some example embodiments, said indication indicative of said at least one time period comprises an indication indicative of a time period during which said first RAT is restricted, and the method further comprises storing said indication of said first RAT with a highest priority in a list of RATs available for said PLMN.

[0122] Where all of the RATs for a PLMN are indicated to be restricted there may be a single time period that is relevant for all the RATs and indeed for the restriction of the PLMN.

[0123] In some example embodiments, said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said current RAT restriction indication and said RAT restriction information, said method comprises storing said received RAT utilisation control information and discarding previously stored RAT utilisation control information.

[0124] The RAT restrictions may be received as part of a RAT utilisation control information element and they may be stored following receipt and previous utilisation information elements for a particular RAT may be overwritten on receipt of an updated value.

[0125] In some example embodiments, said RAT utilisation control information element further comprises said indication of said time period.

[0126] In some example embodiments, said indication is received in one of a deregistration or a registration reject message, and said message comprises information indicating that all RATs supported by said PLMN are restricted for said apparatus, wherein the method comprises determining whether another different PMLN is available and where so request to access to said different PMLN.

[0127] It may be that not only a current or requested RAT is restricted or it may be that a subset of available RATs is restricted, or it may be that all RATs are restricted for this apparatus for a particular PLMN. In the latter case, the method comprises determining whether another different PLMN is available and, where so, requesting access to this other PLMN.

[0128] In some example embodiments said indication is received in a user equipment configuration update message, wherein the method comprises selecting a RAT supported by said PMLN and that is not indicated as being currently restricted for accessing said PMLN.

[0129] The indication may be received in a user configuration update message and in this case the user may select a RAT supported by the PLMN which is not currently being restricted and request access to the PLMN using this RAT. It may do this using a mobility registration update message.

[0130] In some example embodiments, the method is performed by a user equipment or mobile terminal.

[0131] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0132] The computer program may comprise instructions which, when executed by an apparatus, cause the apparatus to perform the optional features set out in relation to the method mentioned above.

[0133] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions stored thereon for performing at least the following: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on the indication and information received.

[0134] The computer program may comprise for performing the optional features set out in relation to the method mentioned above.

[0135] According to various, but not necessarily all, example embodiments of the invention there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; andsending, based on the determining, a request for said access based on the indication and information received.

[0136] The instructions may be for performing the optional features set out in relation to the method mentioned above.

[0137] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0138] In some example embodiments, said message is transmitted in one of: a registration reject message when the user equipment is not registered; a deregistration message or user equipment configuration update message, when the user equipment is already registered.

[0139] In some example embodiments, said information regarding said restrictions comprises a list of restricted RATs.

[0140] In some example embodiments, said method further comprises: determining at least one time period during which at least one of said at least one RAT is restricted for said user equipment; and including an indication of said at least one time period in said message.

[0141] In some example embodiments, said message may comprise an indication of multiple time periods for multiple restricted RATs.

[0142] In some example embodiments, said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said RAT restriction indication and said RAT restriction information.

[0143] In some example embodiments, said RAT utilisation control information element further comprises said indication of said time period.

[0144] In some example embodiments, the method further comprises updating said indication that said one RAT is restricted on expiry of said at least one time period.

[0145] In some example embodiments, said updated RAT restriction indication comprises at least one updated time period.

[0146] In some example embodiments the method is performed by a network control node such as an AMF, MME or 6G-AMF.

[0147] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0148] The computer program may comprise instructions which, when executed by an apparatus, cause the apparatus to perform the optional features set out in relation to the method mentioned above.

[0149] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions stored thereon for performing at least the following: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0150] The computer program may comprise for performing the optional features set out in relation to the method mentioned above.

[0151] According to various, but not necessarily all, example embodiments of the invention there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said atleast one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

[0152] The instructions may be for performing the optional features set out in relation to the method mentioned above.|"Q J **************************

[0154] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the apparatus at least to perform: receiving one of a deregistration or registration reject message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a first public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said first PLMN; determining, based on said RAT type restriction indication and said information indicating that all RATs supported by said apparatus are restricted; determining that a second PLMN is available; and sending, based on the determining, a request for access to said second PLMN.

[0155] An aspect provides a mechanism for indicating to an apparatus such as a mobile user equipment where a requested or current RAT used for connection to a PLMN is not or is no longer appropriate. Information is also supplied to the apparatus regarding restrictions for other RAT types supported by the PLMN. This allows the apparatus to determine whether to request access to a different PLMN or to use a different RAT to access the existing PLMN. In this way dynamic RAT restrictions can be applied to specific UEs such as roaming UEs within for example a VPLMN visited PLMN.

[0156] In some example embodiments, said message comprises a deregistration message when said apparatus is already registered to the first PLMN using the first radio access technology.

[0157] In some example embodiments, said message comprises a registration reject message when said apparatus is requesting to connect to the first PLMN using a first radio access technology.

[0158] In some example embodiments, said information further comprises information regarding restrictions for said apparatus for a plurality of PLMNs and for multiple RAT types supported by said plurality of PLMNs; and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: determining that said second PLMN is available based on said information regarding said restrictions for said plurality of PLMNs and associated RATs; and selecting said second PLMN and a second RAT for requesting access to said second PLMN in dependence upon said information.

[0159] The information provided by the message may also contain information about other PLMNs and RATs for accessing them, along with restriction indications and this allows the apparatus to select a nonrestricted PLMN and a non-restricted RAT to access it where these are available.

[0160] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: receiving at least one indication indicative of at least one time period during which at least one of said RATs that is indicated as restricted is restricted; updating at least one timer associated with said at least one of said restricted RATs based on a respective one of said at least one time period; and inhibiting requesting connection to said first PLMN using said at least one of said restricted RATs during said time period.

[0161] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: storing information regarding RATs that are restricted for said apparatus; and inhibiting requesting connection to a PLMN using a RAT that is stored as restricted.

[0162] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: following determining that all RATs supported by said apparatus are restricted for said first PLMN, storing information regarding said first PLMN as a restricted PLMN; and inhibiting requesting connection to a PLMN that is stored as restricted.

[0163] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: updating said information that is stored for RAT of said RATs that are restricted or PLMNs of said PLMNs that are restricted on expiration of the at least one timer which is associated with the RAT.

[0164] A timer expiring may indicate that the associated RAT is no longer restricted and thus, the information stored regarding this, which may be in the form of a restricted list should be updated. Where a PLMN is indicated as restricted in the stored information because all the RATs for accessing it were restricted, then the update to non-restricted of a RAT for such a PLMN will mean that the PLMN is no longer be viewed restricted and as such, the stored information can be updated to also indicate this. This may involve removing the PLMN and the RAT from the stored restricted list.

[0165] In some example embodiments, said RATs that are restricted comprises a preferred RAT, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: on expiry of said timer associated with said preferred RAT requesting connection to said first PLMN using said preferred RAT.

[0166] In some example embodiments, said indication indicative of said at least one time period comprises an indication indicative of a time period during which said first RAT is restricted, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform storing an indication of said first RAT with a highest priority in a list of RATs available for said first PLMN.

[0167] In some example embodiments, said message comprises RAT utilisation control information, said RAT utilisation control information comprising said restriction indications and said RAT restriction information, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform storing said received RAT utilisation control information and removing previously stored RAT utilisation control information.

[0168] In some example embodiments, said RAT utilisation control information further comprises said indication of said at least one time period.

[0169] According to various, but not necessarily all, example embodiments of the invention there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: determining that a plurality of radio access technology RATs supported for accessing a public land mobile network PLMN are to be restricted for one or more user equipment, said plurality of RATs comprising all RATs that are supported for accessing said PLMN by said at least one user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said plurality of RATs that are to be restricted; generating a deregistration or registration refused message comprising an indication indicating that said plurality of RATs are to be restricted for said user equipment; and transmitting said message to said at least one user equipment.

[0170] In some example embodiments, said message is transmitted in one of: a registration reject message when the user equipment is not registered; or a deregistration message when the user equipment is already registered.

[0171] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: determining at least one time period during which at least one of said plurality of RATs is restricted for said user equipment; and including an indication of said at least one time period in said message.

[0172] In some example embodiments, said message comprises information regarding restrictions for said apparatus for a plurality of PLMNs and for multiple RAT types supported by said plurality of PLMNs.

[0173] In some example embodiments, said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said indication indicating that said plurality of RATs are restricted and said information .

[0174] In some example embodiments, said RAT utilisation control information element further comprises said indication of said at least one time period.

[0175] In some example embodiments, the instructions, when executed by the at least one processor, further cause said apparatus to perform: updating said indication that said at least one of said plurality of RATs is restricted on expiry of said at least one time period.

[0176] In some example embodiments the apparatus is a network control node such as an AMF, MME or 6G-AMF.

[0177] According to various, but not necessarily all, example embodiments of the invention there is provided and apparatus comprising: a means for receiving one of a deregistration or registration reject message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a first public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said first PLMN; means for determining, based on said RAT type restriction indication and said information indicating that all RATs supported by said apparatus are restricted; determining that a second PLMN is available; and means for sending, based on the determining, a request for access to said second PLMN.

[0178] According to various, but not necessarily all, example embodiments of the invention there is provided and apparatus comprising: circuitry for receiving one of a deregistration or registration reject message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a first public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said first PLMN; circuitry for determining, based on said RAT type restriction indication and said information indicating that all RATs supported by said apparatus are restricted; determining that a second PLMN is available; and circuitry for sending, based on the determining, a request for access to said second PLMN.

[0179] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: receiving one of a deregistration or registration reject message comprising a Radio Access Technology RAT type restriction indication indicating that a requested or a registered connection to a first public land mobile network PLMN using a first radio access technology type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said first PLMN; determining, based on said RAT type restriction indication and said information indicating that all RATs supported by said apparatus are restricted; determining that a second PLMN is available; and sending, based on the determining, a request for access to said second PLMN.

[0180] In some example embodiments, said method further comprises determining that said second PLMN is available based on said information regarding said restrictions for said plurality of PLMNs and associated RATs; and selecting said second PLMN and a second RAT for requesting access to said second PLMN in dependence upon said information.

[0181] In some example embodiments, said method further comprises receiving at least one indication indicative of at least one time period during which at least one of said RATs that is indicated as restricted is restricted; updating at least one timer associated with said at least one of said restricted RATs based on a respective one of said at least one time period; and inhibiting requesting connection to said first PLMN using said at least one of said restricted RATs during said time period.

[0182] In some example embodiments, storing information regarding RATs that are restricted for said apparatus; and inhibiting requesting connection to a PLMN using a RAT that is stored as restricted.

[0183] In some example embodiments, said method further comprises updating said information that is stored for RAT of said RATs that are restricted or PLMNs of said PLMNs that are restricted on expiration of the at least one timer which is associated with the RAT.

[0184] In some example embodiments, said method further comprises on expiry of said timer associated with said preferred RAT requesting connection to said first PLMN using said preferred RAT.

[0185] In some example embodiments, said method further comprises said indication indicative of said at least one time period comprises an indication indicative of a time period during which said first RAT is restricted, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform storing an indication of said first RAT with a highest priority in a list of RATs available for said first PLMN.

[0186] In some example embodiments, said message comprises a RAT utilisation control information, said RAT utilisation control information comprising said restriction indications and said RAT restriction information, and said method further comprises storing said received RAT utilisation control information and removing previously stored RAT utilisation control information.

[0187] According to various, but not necessarily all, example embodiments of the invention there is provided a method comprising: determining that a plurality of radio access technology RATs supported for accessing a public land mobile network PLMN are to be restricted for one or more user equipment, said plurality of RATs comprising all RATs that are supported for accessing said PLMN by said at least one user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said plurality of RATs that are to be restricted; generating a deregistration or registration refused message comprising an indication indicating that said plurality of RATs are to be restricted for said user equipment; and transmitting said message to said at least one user equipment.

[0188] In some example embodiments, said method further comprises determining at least one time period during which at least one of said plurality of RATs is restricted for said user equipment; and including an indication of said at least one time period in said message.

[0189] In some example embodiments, said method further comprises updating said indication that said at least one of said plurality of RATs is restricted on expiry of said at least one time period.

[0190] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to the method mentioned above.

[0191] According to various, but not necessarily all, example embodiments of the invention there is provided a computer program comprising instructions or a computer readable medium comprising instructions stored thereon for method mentioned above.

[0192] According to various, but not necessarily all, example embodiments of the invention there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing the method mentioned above.

[0193] A person of skill in the art would readily recognize that steps of various above-described methods can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods. The term non-transitory as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

[0194] As used in this application, the term "circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0195] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merelya hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0196] As used herein, "at least one of the following: ” and "at least one of ” and similar wording, where the list of two or more elements are joined by "and” or "or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0197] The ordering of method steps set out above may not be critical or fixed and the exact ordering of the steps may be varied as appropriate.

[0198] Although example embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

[0199] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

[0200] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0201] Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

[0202] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

WE CLAIM:1 . An apparatus, comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus at least to perform: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested connection or a registered connection to a public land mobile network PLMN using a first RAT type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on said RAT type restriction indication and said information that are received.

2. The apparatus according to claim 1, wherein said message comprises one of: a registration reject message, a deregistration message or a user equipment UE configuration update message.

3. The apparatus according to any preceding claim, wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: receiving at least one indication indicative of at least one time period during which at least one of said RATs that is indicated as restricted is restricted; updating at least one timer associated with said at least one of said restricted RATs based on a respective one of said at least one time period; and inhibiting requesting connection to said PLMN using said at least one of said restricted RATs during said time period.

4. The apparatus according to any preceding claim, wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: storing information regarding RATs that are restricted for said apparatus for said PLMN in the memory of said apparatus; and inhibiting requesting connection to said PLMN using a RAT in the information that is stored regarding RATs that are restricted.

5. The apparatus according to claim 4 when dependent on claim 3, wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: updating said information for RAT of said RATs that are restricted on expiry of the at least one timer which is associated with the RAT.

6. The apparatus according to any one of claims 3 to 5, wherein said RATs that are restricted comprises a preferred RAT, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: on expiry of said at least one timer associated with said preferred RAT, requesting connection to said PLMN using said preferred RAT.

7. The apparatus according to any one of claims 3 to 6, wherein said indication indicative of said at least one time period comprises an indication indicative of a time period during which said first RAT is restricted, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: storing said indication of said first RAT with a highest priority in a list of RATs available for said PLMN.

8. The apparatus according to any preceding claim, wherein said message comprises a RAT utilisation control information, said RAT utilisation control information comprising said information regarding restrictions and said RAT type restriction information, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform storing said received RAT utilisation control information and removing previously stored RAT utilisation control information.

9. The apparatus according to claim 8, when dependent on any one of claims 3 to 7, wherein said RAT utilisation control information further comprises said indication of said at least one time period.

10. The apparatus according to any preceding claim, wherein said indication is received in one of a deregistration message or a registration reject message, and said one or said deregistration message or said registration reject message comprises information indicating that all RATs supported by said PLMN are restricted for said apparatus, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to determine whether another different PMLN is available and when so to request to access to said another different PMLN.

11. The apparatus according to any preceding claim, wherein said indication is received in a user equipment configuration update message, and wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: selecting a RAT supported by said PMLN and that is not indicated as being currently restricted for accessing said PMLN.

12. An apparatus, comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus at least to perform: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

13. The apparatus according to claim 12, wherein said message is transmitted in one of: a registration reject message when the user equipment is not registered; a deregistration message or user equipment configuration update message, when the user equipment is already registered.

14. The apparatus according to claim 12 or 13, wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: determining at least one time period during which at least one of said at least one RAT is restricted for said user equipment; and including an indication of said at least one time period in said message.

15. The apparatus according to any one of claims 12 to 14, wherein said message comprises a RAT utilisation control information element, said RAT utilisation control information element comprising said indication indicating that said one RAT is restricted and said information regarding restrictions.

16. The apparatus according to claim 15, when dependent upon claim 14, wherein said RAT utilisation control information element further comprises said indication of said at least one time period.

17. The apparatus according to claim 14 or 15 wherein the instructions, when executed by the at least one processor, further cause said apparatus to perform: updating said indication that said one RAT is restricted on expiry of said at least one time period.

18. A method comprising: receiving a message comprising a Radio Access Technology RAT type restriction indication indicating that a requested connection or a registered connection to a public land mobile network PLMN using a first RAT type is restricted for said apparatus, said message further comprising information regarding restrictions for said apparatus for other RAT types supported by said PLMN; determining, based on said RAT type restriction indication and said information, to request access to one of: said PLMN using a RAT that is not indicated as being restricted or a different PLMN; and sending, based on the determining, a request for said access based on said RAT type indication and said information that are received.

19. A method comprising: determining that at least one radio access technology RAT for accessing a public land mobile network PLMN is to be restricted for one or more user equipment; determining that at least one user equipment of said one or more user equipment is accessing or requesting access to said PLMN using one RAT of said at least one RAT that is to be restricted; generating a message comprising an indication indicating that said one RAT is restricted for said user equipment, said message further comprising information regarding restrictions for said user equipment with respect to other RAT of said at least one RAT that is to be restricted and that is supported by said PLMN; and transmitting said message to said at least one user equipment.

20. A computer program which when executed by a processor of an apparatus causes said apparatus to perform the method of claim 18 or 19.

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