GB2611499A

GB2611499A - Data session management

Info

Publication number: GB2611499A
Application number: GB2300956.6A
Authority: GB
Inventors: Watfa Mahmoud
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2020-03-23
Filing date: 2020-03-23
Publication date: 2023-04-05
Anticipated expiration: 2040-03-23
Also published as: GB2611499B; GB202300956D0

Abstract

User equipment (UE) determines whether it supports transfer of data over the user plane and, if the UE supports transfer of data over the user plane, the UE transmits, to a network entity, a data session establishment request including an indication of a maximum data rate for the data session. If the UE does not support transfer of data over the user plane, the UE transmits, to the network entity, a data session establishment request including a value (e.g. predetermined value) indicating that the UE does not support transfer of data over the user plane. If the data session establishment request includes the value or does not include an indication of a maximum data rate, the network entity may determine that the UE does not support user plane integrity protection. The established data session may be a PDU session and the indication may comprise an integrity protection maximum data rate IE.

Description

Intellectual Property Office Application No G132300956.6 RTM Date:30 January 2023 The following term is a Registered Trade Mark and should be read as such wherever it occurs in this document: 3 GP P Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

Data Session Management BACKGROUND

Field

Certain examples of the present disclosure provide methods, apparatus and systems for managing data sessions in a network. For example, certain examples of the present disclosure provide methods, apparatus and systems for managing PDU sessions for NB-IoT in 3GPP 5GSM.

Description of the Related Art

Herein, the following documents are referenced: [1] 3GPP TS 23.501 V16.3.0 [2] 3GPP TS 24.501 V16.3.0 [3] 3GPP TS 23.502 V16.3.0 [4] 3GPP TS 24.301 V16.3.0 Various acronyms and abbreviations used herein are defined at the end of this description.

The above documents disclose various operations and procedures, including the following.

Overview of the Integrity protection maximum data rate IE in the PDU Session Establishment Request message 5GS enables the application of integrity protection to the UP of a PDU session as described in IS 23.501 [1]: The SMF determines at PDU session establishment a User Plane Security Enforcement information for the user plane of a PDU session based on: - subscribed User Plane Security Policy which is part of SM subscription information received from UDM; and - User Plane Security Policy locally configured per (DNN, S-NSSAI) in the SMF that is used when the UDM does not provide User Plane Security Policy information.

- The maximum supported data rate per UE for integrity protection for the DRBs, provided by the UE in the Integrity protection maximum data rate IE during PDU Session Establishment.

As per the above, the UE is required to provide the Integrity protection maximum data rate IE in the PDU Session Establishment Request message as specified in TS 24.501 [2] i.e. this IE is a mandatory IE in the PDU Session Establishment Request as shown below, highlighted in bold and underline: Table 1: PDU SESSION ESTABLISHMENT REQUEST message content (corresponds to Table 8.3.1.1.1 from [2]) The support of data transfer over the user plane may also be referred to as N3 data transfer, as indicated by the "N3 data" bit of the 5GMM capability IE that is defined in [2]. As such, the term "N3 data transfer" may also mean the transfer of data over the user plane.

Handling of PDU sessions during idle mode inter-RAT mobility to/from NB-IoT The NB-IoT RAT is deployed such that the TAls do not overlap with those in WB-EUTRA or NR as described in [1]: Tracking Areas are configured so that they do not contain both NB-loT and other RA Ts cells, so when the UE is changing RAT type to or from NB-loT while remaining registered with 530, the UE will perform the Mobility Registration Update procedure, see clause 5.3.2.3. When the UE is changing RATtype to or from NB-loT and moving between 5GC and EPC, during the Registration, Attach or TAU procedure the RAT type change is determined Information Element Type/Reference Presence Format Length 1E1 Integrity protection maximum data rate Integrity protection maximum data rate 9.11.4.7

V olr

H3*33t3E* c3-.33;p3,s..;;;3r; C'* C3-1 * C.31-I PDU session handling is controlled by "PDU Session continuity at inter RAT mobility" in the UEs subscription data, which indicates per DNN/S-NSSAI whether to; - maintain the PDU session, - disconnect the PDU session with a reactivation request, S -disconnect the PDU session without reactivation request, or - leave it up to local VPLMN policy when the UE moves between a "broadband" RAT (e.g. NR or WB-E-UTRAN) and a "narrowband" RAT (NB-loT).

During PDU session establishment the SMF retrieves the "PDU Session continuity at inter RAT mobility" subscription information (if available) from the UDM. Local SMF configuration is used if "PDU Session continuity at inter RAT mobility is not available for a PDU Session The AMF informs the SMF at an inter-RAT idle mobility event, e.g. to or from NB-loT connected to 5GC about the RAT type change in the Nsmf POUSession_UpdateSMContext message during the Registration procedure. Based on this (F1-)SMF handles the PDU session according to "PDU session continuity at inter RAT mobility information" subscription data or based on local policy.

NOTE: The "PDU Session continuity at inter RAT mobility" and "PDN continuity at inter-RAT mobility" subscription should be the same so that the PDU sessions/PDN connections are handled the same by both CN types.

During inter-RAT idle mode mobility to NB-1oT, if a PDU session has more than one QoS rule, the SMF shall initiate a PDU session modification procedure as described in TS 23.502 [3] to remove any non-default QoS rule, and maintain only the default QoS rule.

As also indicated above, when the UE moves into an NB-loT coverage or RAT, for which the TAls are non-overlapping with other RATs, the SMF determines whether or to keep the session based on the "PDU Session continuity at inter RAT mobility" in the UEs subscription data and/or local policies. If the session is kept for an NB-IoT device (also known as UE in NB-N1 mode), the SMF "shall initiate a PDU session modification procedure as described in TS 23.502 [3J to remove any non-default QoS rule, and maintain only the default QoS rule".

In general, during a PDU session modification procedure, the UE checks for errors in QoS rules. For example, since a PDU session must always have a default QoS rule, then the delete operation on the default QoS rule should not be permitted. Accordingly, the UE will release the PDU session if such an error occurs as described below from section 6.3.2.4 in [2]: [ SKIP] If the PDU SESSION MODIFICATION COMMAND message includes the Authorized QoS rules 1E, the UE shall process the QoS rules sequentially starting with the first QoS rule. The UE shall check the QoS rule and the QoS flow description provided in the PDU SESSION MODIFICATION COMMAND message for different types of errors as follows: NOTE 4 If an error is detected in a QoS rule or a QoS flow description which requires rejecting the PDU SESSION MODIFICATION COMMAND message, then the Authorized QoS rules 1E, the Authorized QoS flow descriptions IE and the Mapped EPS bearer contexts IE included in the PDU SESSION MODIFICATION COMMAND message are discarded, if any a) Semantic errors in QoS operations: 1) When the rule operation is "Modify existing QoS rule and add packet filters", "Modify existing QoS rule and replace all packet filters", "Modify existing QoS rule and delete packet filters" or "Modify existing QoS rule without modifying packet filters" on the default QoS rule and the DQR bit is set to "the QoS rule is not the default QoS rule".

2) When the rule operation is "Modify existing QoS rule and add packet filters", "Modify existing QoS rule and replace all packet filters'; "Modify existing QoS rule and delete packet tillers" or "Modify existing QoS rule without modifying packet filters" on a QoS rule which is not the default QoS rule and the DOER bit is set to 'Me QoS rule is the default QoS rule".

3) When the rule operation is "Create new QoS rule" and the DOER bit is set to "the QoS rule is the default QoS rule" when there's already a default QoS rule with different QoS rule identifier.

4) When the rule operation is "Delete existing QoS rule" on the default QoS rule.

5) When the rule operation is "Create new QoS rule", "Modify existing QoS rule and add packet filters", "Modify existing QoS rule and replace all packet filters", "Modify existing QoS rule and delete packet filters ", or "Modify existing QoS rule without modifying packet filters" and two or more QoS rules associated with this PDU session would have identical precedence values.

6) When the rule operation is "Modify existing QoS rule and delete packet filters", the QoS rule is a OoS rule of a PDU session of 1Pv4, 1Pv6, IPv4v6 or Ethernet PDU session type, and the packet filter fist in the resultant QoS rule is empty.

7) When the rule operation is "Create new QoS rule" and there is already an existing QoS rule with the same QoS rule Identifier 8) When the rule operation is "Modify existing QoS rule and add packet filters", "Modify existing QoS rule and replace all packet filters", "Modify existing QoS rule and delete packet filters" or "Modify existing QoS rule without modifying packet filters" and the associated QoS rule does not exist.

9) When the rule operation is "Delete existing QaS rule" and there is no existing QoS rule with the same QoS rule identifier.

10)When the flow description operation is "Create new QoS flow description" and there is already an existing QoS flow description with the same QoS flow identifier 11)When the flow description operation is "Modify existing QoS flow description" and the associated QoS flow description does not exist.

12)When the flow description operation is "Delete existing QoS flow description" and there is no existing QoS flow description with the same QoS flow identifier In case 4, the UE shall initiate a PDU session release procedure by sending a PDU SESSION RELEASE REQUEST message with 5GSM cause #83 "semantic error in the QoS operation".

In case 5, lithe old QoS rule (i.e. the QoS rule that existed before the PDU SESSION MODIFICATION COMMAND message was received) IS not the default QoS rule, the UE shall not diagnose an error, shall further process the new request and, lilt was processed successfully, shall delete the old QoS rule which has identical precedence value. Furthermore, after sending the PDU SESSSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall send a PDU SESSION MODIFICATION REQUEST message with 5GSM cause #83 "semantic error in the QoS operation" to delete the QoS rule.

In case 5, lithe old QoS rule (i.e. the QoS rule that existed before the PDU SESSION MODIFICATION COMMAND message was received) is the default QoS rule, the UE shall initiate a PDU session release procedure by sending a PDU SESSION RELEASE REQUEST message with 5GSM cause #83 "semantic error in the QoS operation".

In case 6, if the QoS rule is not the default QoS rule, after sending the POLL SESSSION MODIFICATION COMPLETE for the ongoing PDU session modification procedure, the UE shall send a PDU SESSION MODIFICATION REQUEST message with 5GSM cause #83 "semantic error in the QoS operation" to delete the QoS rule.

In case 6, if the QoS rule is the default QoS rule, the UE shall initiate a PDU session release procedure by sending a POLL SESSION RELEASE REQUEST message with 5GSM cause #83 "semantic error in the QoS operation".

In case 7, if the existing QoS rule is not the default QoS rule and the DQR bit of the new QoS rule is set to "the QoS rule is not the default QoS rule", the UE shall not diagnose an error, further process the create request and, if it was processed successfully, delete the old QoS rule. If the existing QoS rule is the default QoS rule or the DQR bit of the new QoS rule is set to "the QoS rule is the default QoS the UE shall reject the PDU SESSION MODIFICATION COMMAND message with 5GSM cause #83 "semantic error in the QoS operation".

In case 9, the UE shall not diagnose an error, further process the delete request and, if it was processed successfully, consider the respective QoS rule as successfully deleted.

In case 10, the UE shall not diagnose an error, further process the create request and, if it was processed

successfully, delete the old QoS flow description.

In case 12, the UE shall not diagnose an error, further process the delete request and, if it was processed successfully, consider the respective QoS flow description as successfully deleted.

Otherwise, the UE shall reject the PDU SESSION MODIFICATION COMMAND message with 5GSM cause #83 "semantic error in the QoS operation".

[ SKIP...] The excerpt above shows that the delete operation on the default QoS rule (case 4 above) will lead to the release of the PDU session i.e. the UE will send the PDU Session Release Request message Another error that can occur is that shown in case 3 above, i.e. when there is a create operation and the QoS rule is indicated to be a default QoS rule (i.e. the DQR bit is set to "the QoS rule is the default QoS rule") and the UE already has a default QoS rule. In this case, the UE will reject the PDU SESSION MODIFICATION COMMAND message with 5GSM cause #83 "semantic error in the QoS operation".

The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.

SUMMARY

It is an aim of certain examples of the present disclosure to address, solve and/or mitigate, at least partly, at least one of the problems and/or disadvantages associated with the related art, for example at least one of the problems and/or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

The present invention is defined in the independent claims. Advantageous features are defined in the dependent claims.

Other aspects, advantages, and salient features will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the annexed drawings, which disclose examples of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates an exemplary coding of an Integrity protection maximum data rate IE of type TLV, and Figure 2 is a block diagram of an exemplary network entity that may be used in certain

examples of the present disclosure.

DETAILED DESCRIPTION

The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of the present invention, as defined by the claims. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the invention.

The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

Detailed descriptions of techniques, structures, constructions, functions or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present invention.

The terms and words used herein are not limited to the bibliographical or standard meanings, but, are merely used to enable a clear and consistent understanding of the invention.

Throughout the description and claims of this specification, the words "comprise", "include" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and/or groups thereof.

Throughout the description and claims of this specification, the singular form, for example "a", "an" and "the", encompasses the plural unless the context otherwise requires. For example, reference to "an object" includes reference to one or more of such objects.

Throughout the description and claims of this specification, language in the general form of "X for Y" (where Y is some action, process, operation, function, activity or step and X is some means for carrying out that action, process, operation, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y. Features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and/or groups thereof described or disclosed in conjunction with a particular aspect, embodiment, example or claim of the present invention are to be understood to be applicable to any other aspect, embodiment, example or claim described herein unless incompatible therewith.

Certain examples of the present disclosure provide methods, apparatus and systems for managing data sessions in a network. For example, certain examples of the present disclosure provide methods, apparatus and systems for managing PDU sessions for NB-IoT in 3GPP 5GSM. However, the skilled person will appreciate that the present invention is not limited to these examples, and may be applied in any suitable system or standard, for example one or more existing and/or future generation wireless communication systems or standards.

The following examples are applicable to, and use terminology associated with, 3GPP 5G. However, the skilled person will appreciate that the techniques disclosed herein are not limited to 3GPP 5G. For example, the functionality of the various network entities and messages disclosed herein may be applied to corresponding or equivalent entities and messages in other communication systems or standards. Corresponding or equivalent entities and messages may be regarded as entities and messages that perform the same or similar role within the network. The skilled person will also appreciate that the transmission of information between network entities is not limited to the specific form, type or order of messages described in relation to the examples disclosed herein.

A particular network entity may be implemented as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and/or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

The skilled person will appreciate that the present invention is not limited to the specific examples disclosed herein. For example: * The techniques disclosed herein are not limited to 3GPP 5G.

* One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations.

* One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information.

* One or more further elements or entities may be added to the examples disclosed herein.

* One or more non-essential elements or entities may be omitted in certain examples.

* The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example.

* The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example.

* Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example.

* Information carried by two or more separate messages in one example may be carried by a single message in an alternative example.

* The order in which operations are performed and/or the order in which messages are transmitted may be modified, if possible, in alternative examples.

Certain examples of the present disclosure may be provided in the form of an apparatus/device/network entity configured to perform one or more defined network functions and/or a method therefor. Certain examples of the present disclosure may be provided in the form of a system comprising one or more such apparatuses/devices/network entities, and/or a method therefor.

In the techniques of the related art, for example those referred to above, there occur the following problems.

1. The Integrity protection maximum data rate IE is applicable to the user plane but not all NB-IoT devices support data over the user plane NB-IoT UEs are mandatorily required to support data transfer over the control plane. However, support for data transfer over the user plane is optional for these UEs.

Even when an NB-loT device does not support data transfer over the user plane, the current format of the PDU Session Establishment Request message mandates that the UE indicates the supported data rate for which integrity protection can be applied on the user plane.

This creates ambiguity in the 5GSM protocol as the UE is mandated to provide information for a feature that it does not actually support. Moreover, such UEs will be forced to send two additional octets (as the IE is currently 2 octets long) which unnecessarily increases the NAS message size. This renders it inefficient for NB-IoT devices that are in low coverage areas, for which the RAN may configure the UE to repeat radio transmissions several times due to the use of coverage enhancement (i.e. when the UE is in a bad coverage). The unnecessary presence of two octets at the NAS can actually lead to multiple lower layer transmissions if the coverage level is very bad, especially when the entire NAS message cannot fit into one lower layer message for transmission. The additional two octets at the NAS can actually lead to segmentation of the NAS message into two parts depending on the transport block size that the UE is provided with.

A solution is thus needed to avoid a situation in which an NB-IoT UE sends information related to the user plane when the UE does not actually support data transfer over the user plane.

2. Errors associated with the PDU session modification procedure to delete all non-default QoS rules after mobility into NB-IoT RAT As described earlier, when the UE enters NB-IoT RAT or coverage and the SMF decides to maintain an established PDU session for the UE, the SMF performs a PDU session modification procedure to delete all the QoS rules that are not a default QoS rule but will keep the default rule only. This means that if the UE has three PDU sessions, as an example, then for each session there is a need to perform a PDU session modification procedure. If the UE is in a bad coverage, the UE and/or the RAN may need to retransmit the 5GSM message a few times as configured by the RAN, and this increases overall signalling and power consumption at the UE.

Moreover, if the UE detects certain errors in the QoS rules when the SMF sends the 5GSM message, e.g. if the deleted QoS rule is a default QoS rule, then the UE will release the PDU session thereby causing more signalling to be exchanged and that is not power efficient for NB-IoT devices. This will in turn lead to more signalling to re-establish the PDU session again.

Additionally, as the UE in NB-IoT cannot have any non-default QoS rule, then if the UE receives the PDU Session Modification Command message with a QoS rule operation that is the create operation, i.e. to create a new QoS rule, then this should be considered as an error even if the create operation itself is not problematic. In this case, the operation on QoS rule should not be anything other than a delete operation for the non-default QoS rules. The UE is currently not required to check for such errors which are typically not considered an error from a 5GSM protocol point of view. But since the UE is in NB-IoT, the UE will need to apply different checks to these rules.

Such problems are not yet solved 3. Errors associated with a PDU session establishment procedure for a UE in NB-loT RAT As described earlier, the UE in NB-IoT RAT can only have a default QoS rule that is associated with a PDU session. As errors can occur during the PDU session establishment procedure, it is possible that the PDU Session Establishment Request message can have multiple QoS rules with the create operation. However, since only one QoS rule can be available (and that is the default QoS rule) then any additional QoS rule with a create operation should be considered an error. The UE behaviour in this case is not yet specified but should be.

Certain examples of the present disclosure address the above problems, for example by providing one or more of the techniques described below.

In certain examples of the present disclosure, a UE which does not support transfer of data over the user plane should not send any information about the integrity protection of the user plane. Hence the corresponding field in the PDU Session Establishment Request message and in the PDU Session Modification Request message should be optional and should only be sent by UEs that support the transfer of data via the user plane (also known as N3 data transfer) Certain examples of the present disclosure provide an efficient technique to not use the non-default QoS rules when in NB-IoT RAT, by either performing a local delete of these rules or by saving them for subsequent use after mobility out of NB-loT. Alternatively, if required to be deleted explicitly, in certain examples of the present disclosure the UE verifies the possibility of errors in QoS operations and applies a technique to recover from such errors.

Certain examples of the present disclosure will now be described in more detail.

1. Handling the Integrity protection maximum data rate IE in the PDU Session Establishment Request message As indicated above, the NB-IoT UE may not support data transfer over the user plane. Therefore, it is not necessary that the UE indicates the integrity protection rate for the user plane that is anyways not supported. Various examples of the present disclosure provide a number of solution options to address this problem.

Solution Option 1 In certain examples of the present disclosure, the Integrity protection maximum data rate IE should be an optional IE or a conditional IE in the PDU Session Establishment Request message The UE, optionally an NB-1°T UE, that does not support N3 data transfer (or transfer of data over the user plane) should not send this 1E in the PDU Session Establishment Request message. Otherwise, the UE supporting N3 data transfer shall send the IF in the PDU Session Establishment Request message.

This solution requires that the Integrity protection maximum data rate IF become an optional 1E, for example as indicated in Table 2 below: 1E1 Information Element Type/Reference Presence Format Length 0 or C 4 or 3 Integrity protection maximum data rate Integrity protection maximum data rate 9.11.4.7 TLV or TV

PDU

Table 2: PDU SESSION ESTABLISHMENT REQUEST message content with the Integrity protection maximum data rate IE as optional In certain examples, if the Integrity protection maximum data rate IE is defined to be of type TLV, then the IE should be coded as shown in Figure 1.

In certain examples, the Integrity protection maximum data rate IE should only be sent in the PDU Session Modification Request message for a PDN connection established when in Si mode, after the first inter-system change from Si mode to Ni mode, the UE is operating in single-registration mode in the network supporting N26 interface, and if the UE supports data transfer over the user plane (i.e. the UE supports N3 data transfer).

In certain examples, the UE which does not support N3 data transfer may indicate the same to the network so that the SMF is aware that the Integrity protection maximum data rate field is not sent in the 5GSM message.

For example, the indication that the UE can provide may be in one or more of the following ways: * The UE may include the indication in the UL NAS TRANSPORT message which carries the 5GSM message. The indication may be in the form of a new IE where the new IE may be of type TV or TLV, or T, or any other type. The IE may have a value component, optionally in the form of bit positions, where a specific value may be defined for the value component to indicate that N3 data transfer is not supported by the UE. The UE may optionally send include this indication when sending every 5GSM message.

* An existing IF or field in the UL NAS TRANSPORT message may be used for this purpose as described above. For example, the existing Request type IF in the UL NAS TRANSPORT message can be used for this purpose. For example, the reserved value "111" can be used to mean "initial request without N3 data transfer" where the value indicates that the request is a new request (i.e. to establish a new PDU session) while also indicating that the UE does not support N3 data transfer.

* Defining and using a new 5GSM message identity, i.e. a new 5GSM message (e.g. a PDU Session Establishment Request for Control Plane Data). Hence the UE that does not support N3 data transfer may use the new 5GSM message (as described herein) to establish a PDU session. This message will not contain the Integrity protection maximum data rate IE and the 5GSM message will be like the message shown in Table 2 but without the Integrity protection maximum data rate IE.

The AMF may determine that the UE does not support (or does support) N3 data transfer based on the "N3 data" bit (e.g. bit 6 of octet 3) in the 5GMM capability IE. For such UEs, when the AMF receives an UL NAS TRANSPORT with a new indication that N3 data transfer is not supported (as described above), the AMF should in turn forward this indication to the SMF over the N11 (or Nsmf) reference point (see 3GPP TS 23.501). Note that the indication on the N11 (or Nsmf) reference point may be in the form of a new value for an existing parameter or may be introduced as a new parameter. Regardless, the indication informs the SMF that N3 data transfer is not supported by the UE.

When the SMF receives an indication from the AMF (e.g. over the N11 (or Nsmf) reference point or using a new parameter or a new value for an existing parameter) that the UE does not support N3 data transfer, the SMF determines that the PDU Session Establishment Request message does not include the Integrity protection maximum data rate field and would therefore expect the 5GSM message to be like the one shown in Table 2 but without the Integrity protection maximum data rate IE Solution Option 2 In certain examples of the present disclosure, the UE sends Integrity protection maximum data rate IE optionally as a mandatory IE but sets the value to a specific value.

In this solution option, the IE is optionally kept as a mandatory IE but a reserved or specific value is defined to be used by a UE, optionally an NB-IoT UE, that does not support N3 data transfer. As an example, the value "011111111" can be used for such UEs that don't support N3 data transfer and as such these UEs will set the value component of the IE to this specific value. The value "011111111" may be interpreted as, "NULL", or "user-plane integrity protection is not supported", or "user-plane integrity protection is not supported for uplink", or "user-plane integrity protection is not supported for downlink", where based on the direction being referred to the particular interpretation can apply. The skilled person will appreciate that this value i.e. "011111111" is to be taken as an example and that any other suitable value can be defined for this purpose. Moreover, the skilled person will appreciate that the interpretations provided above are to be taken as examples and that other interpretations can be defined instead e.g. "control plane only device", etc. When the SMF receives this IE in the 5GSM message with a specific value as described above, the SMF determines that user plane integrity protection is not supported for this UE and may set the integrity protection requirement as not needed.

As another alternative of this option, the UE may set the I E to any value.

In certain examples, with any of the alternatives above, when the SMF receives a PDU Session Establishment Request message, that is forwarded by the AMF, and also receives the Control plane only indication from the AMF, or any of the other indications described herein, then based on the received indication (e.g. the Control plane only indication), the SMF determines that the integrity protection for the user plane associated with this PDU session is not required. The SMF can then ignore these received values.

2. Handling QoS rules after inter-RAT mobility into an NB-1°T RAT Solution Option 1 In order to reduce signalling for NB-IoT, in certain examples, upon mobility into NB-IoT RAT, the UE and the SMF may locally delete all the QoS rules that are not the default QoS rules and maintain only the default QoS rule. This will avoid the need to initiate a PDU session modification procedure as is currently done. Moreover, the UE and the SMF may optionally set the packet filter that is associated with the default QoS rule to a match all filter for the uplink and optionally for downlink direction such that all the traffic associated with this PDU session will be mapped or matched to the default QoS rule.

In an alternative example, the UE may verify for additional errors that are associated with the PDU Session Modification Command message for this particular case of being in NB-IoT RAT. Since the UE in NB-IoT can only have one QoS rule and that should be the default QoS rule, then the 5GSM message should only contain QoS rules with delete operations so that all the non-default QoS rules (i.e. all the QoS rules that are not the default QoS rule) will be deleted as required. To ensure this is the case, in certain examples the UE should perform the following checks while in NB-IoT and the PDU Session Modification Command message is received: * The UE should check if there is a QoS rule with the rule operation set to: o "Create new QoS rule" and optionally the DQR bit is not set to "the QoS rule is not the default QoS rule", o "Modify existing QoS rule and add packet filters", "Modify existing QoS rule and replace all packet filters", "Modify existing QoS rule and delete packet filters" or "Modify existing QoS rule without modifying packet filters" and optionally the operation is on the non-default QoS rules.

* Alternatively, the UE for each non-default QoS rule, the UE checks if the operation is different from "Delete existing QoS rule". If so, the UE determines that the QoS rule is erroneous and proceeds as described herein. Note that this is just another way to achieve the check that is proposed above.

If the above occurs, the UE shall, after the completion of the current PDU session modification procedure, send a PDU Session Modification Request message to delete each of the QoS rule that is not the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each QoS rule which is not the default QoS rule.

Alternatively, the UE shall initiate the PDU session release procedure (optionally after the completion of the ongoing PDU session modification procedure) by sending the PDU Session Release Request message.

Alternatively, the UE shall reject the PDU session modification procedure (i.e. the UE rejects PDU Session Modification Command message) by sending the PDU Session Modification Command Reject message.

* The UE should check if there is a QoS flow description with the flow description operation set to: o "Create new QoS flow description" for which the QoS flow identifier is not associated with the QoS flow identifier of the default QoS rule, o "Modify existing QoS flow description" for which the QoS flow identifier is not associated with the QoS flow identifier of the default QoS rule.

* Alternatively, the UE for each QoS flow description with a OR that is associated with the non-default QoS rule, the UE checks if the operation is different from "Delete existing QoS flow description". If so, the UE determines that the QoS flow description is erroneous and proceeds as described herein. Note that this is just another way to achieve the check that is proposed above.

If the above occurs, the UE shall, after the completion of the current PDU session modification procedure, send a PDU Session Modification Request message to delete each QoS flow description that has a OH which is not the same as the QFI of the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each QoS flow description that has a OH which is not the same as the QFI of the default QoS rule.

Alternatively, the UE shall initiate the PDU session release procedure by sending the PDU Session Release Request message.

* The UE should check if there is at least one mapped EPS bearer operation (in the Mapped EPS bearer contexts I E if received) with the operation code set to: o "Create new EPS bearer" and the associated QoS flow identifier (QED corresponds to a QoS rule that is not the default QoS rule, o "Modify existing EPS bearer" and the associated QoS flow identifier (QFI) corresponds to a QoS rule that is not the default QoS rule.

* Alternatively, the UE for each Mapped EPS bearer context with a OH that is associated with the non-default QoS rule, the UE checks if the operation is different from "Delete existing EPS bearer". If so, the UE determines that the Mapped EPS bearer context is erroneous and proceeds as described herein. Note that this is just another way to achieve the check that is proposed above.

If the above occurs, the UE shall, after the completion of the current PDU session modification procedure, send a PDU Session Modification Request message to delete each mapped EPS bearer context with a OR that is not the same as the QFI of the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each mapped EPS bearer context with a QFI that is not the same as the OF! of the default QoS rule.

In the examples described above, the UE may detect a few errors as described above. The UE may still take one action in this case as proposed above.

In certain examples, when sending a PDU Session Modification Request message (e.g. to delete at least one QoS rule, or at least one QoS flow description, or at least one Mapped EPS bearer context), or when sending a PDU Session Release Request message, the UE can include any existing 5GSM cause (e.g. #83 "semantic error in the QoS operation") in the 5GSM message. Alternatively, the UE shall use a new 5GSM cause set for each of the errors defined above, or a new 5GSM cause that can be generic and would apply to all of the cases listed above. As an example, the UE can use a new 5GSM cause set to "Operation not allowed due to UE in NB-N1 mode".

The skilled person will appreciate that the examples above may also be applied when the UE is in EPS (i.e. in Si mode) and the PDN connection is transferable to Ni mode. As such, the UE should check for the same errors when the UE in N B-loT in Si mode receives any of the existing ESM messages, for example that are defined in TS 3GPP 24.301 [4]. For example, the UE should check for the same errors listed above in the QoS rules that are received in the Protocol configuration options IE or Extended protocol configuration options I E in the MODIFY EPS BEARER CONTEXT REQUEST message (where the latter is the ESM NAS message that is received in Si mode). Similarly, an existing 5GSM cause can be used when sending an ESM message by the UE (e.g. the MODIFY EPS BEARER CONTEXT ACCEPT message) to report an error, for example as described in section 6.1.4.1 of [2].

Accordingly, the skilled person will appreciate that all the examples above may be applied when the UE is in either Ni mode or Si mode.

Solution Option 2 In certain examples, the QoS parameters (i.e. QoS rules, QoS flow descriptions, or Mapped EPS bearer contexts) that are not the default QoS rule, or are not associated with the default QoS rule, will be locally saved at the UE and the SMF when the UE enters NB-loT (or when the UE is operating in NB-N1 mode). As the UE may support other RATs, such as WE-EUTRA or NR, then upon mobility from NB-loT to another RAT the restriction about having only a default QoS rule will be lifted and the UE can then have QoS rules that are not a default QoS rule and can also have other associated QoS parameters (e.g. QoS flow descriptions or Mapped EPS bearer contexts).

As such, in certain examples of the present disclosure, when the UE enters NB-IoT, the UE should locally save a copy of all the non-default QoS parameters (i.e. each QoS rule that is not a default QoS rule and any associated QoS flow description or Mapped EPS bearer context). The UE in NB-IoT will then only use the default QoS rule and any other associated QoS parameter (e.g. QoS flow description or Mapped EPS bearer context).

Herein, the term "QoS parameters" may refer to any suitable parameters, for example QoS rules, QoS flow descriptions, or Mapped EPS bearer contexts in the examples below.

In certain examples, to save the QoS parameters, the UE may save a QoS parameter context and a corresponding QoS parameter context ID. For example, the QoS parameter context and a corresponding QoS parameter context ID may be in the following form: * A list of QoS rule identifier for each QoS rule and: o For each QoS rule, an associated QoS flow description (where the association between the QoS rule and the QoS flow description is based on a QFI) o For each QoS rule, an associated Mapped EPS bearer context (where the association between the Mapped EPS bearer context and the QoS flow description may be based on a QFI and optionally an EPS bearer identity (ID)) * In certain examples, the Mapped EPS bearer context may be represented in the form of an EPS bearer ID and all the other EPS related QoS parameters (e.g. TFT, packet filters, etc, for example as defined in [2] and [4]).

o QoS parameter context ID corresponding to each QoS rule identifier * In certain examples, the QoS parameter context ID may be part of the saved QoS parameter context.

In certain examples, the QoS parameter context may be saved per PDU session.

Similarly, the SMF may apply similar behaviour as described above, noting that the SMF becomes aware of the UE's mobility into NB-loT based on an indication from the AMF.

In certain examples, the UE that supports saving locally of the QoS parameters as described above may indicate this support either in the 5GMM capability IE or the 5GSM capability IE. For example, a new bit position in these IEs may be used for this purpose, e.g. "Saving of QoS parameters locally is supported" can be used, or any other suitable definition can be used for this purpose.

Similarly, in certain examples the network (e.g. AMF or SMF) may indicate if this is also supported in the network. For example, the AMF can indicate if this is supported by defining a similar bit in the 5GS network feature support I E (defined in [2]) that indicates that the network supports and allows the use of this feature. Alternatively, the SMF can indicate that it supports and allows the use of this feature by defining and using a similar bit in the 535M network feature support IE (defined in [2]). The network may indicate whether this is allowed for a UE based on the UE's capability and optionally the subscription information or local policies in the network.

In certain examples, the UE may operate in the manner described above if the network indicates that saving QoS parameters locally is allowed or the UE operates in this manner by default whenever the UE enters NB-IoT.

Although the QoS parameters are saved locally, certain examples of the present disclosure may define a new QoS operation that indicates the saving of QoS parameters as described above. The operation may be called, as an example, "Save existing QoS rule".

In certain examples, the SMF may send a PDU Session Modification Command message to the UE after the SMF receives an indication that the UE has entered NB-IoT. The SMF may do this to inform the UE to save its QoS parameters. To do so, the SMF may set the QoS operation code to "Save existing QoS rule" for each of the QoS rule identifier. In certain examples, a similar operation may be defined for the QoS flow descriptions and the Mapped EPS bearer context. Alternatively, by indicating a specific QoS rule to be saved, the SMF and UE may also save all corresponding QoS parameters.

The use of this operation can also implicitly lead to the UE and SMF to use the default QoS rule only and its corresponding QoS parameters. Hence, when this new operation is used, the recipient saves all the QoS parameters that are currently available for the PDU session and then continues to use the default QoS rule and its corresponding QoS parameters as long as the UE is in NB-IoT.

Therefore, for example, when the UE enters NB-IoT, the SMF may send a PDU Session Modification Command message to the UE and set the operation code to "Save existing QoS rule" for each of the QoS rule identifier that should be saved. The UE and SMF both save all the QoS parameters accordingly that correspond to each QoS rule identifier for which this operation is used. The UE may then send the PDU Session Modification Complete message. Optionally, the UE may acknowledge the saving of the QoS parameters locally by including the QoS rule IF and setting the operation code to "Save existing QoS rule" for each of the QoS rule identifier for each of the QoS rule that has been saved (and optionally the corresponding QoS parameters that are associated with that QoS rule).

Alternatively, a new IF with a list of QoS rule identifier can be used by either the UE or the SMF and include it in a 5GSM message to indicate the list of QoS rule identifiers that have been locally saved.

Alternatively, the UE may be the entity that sends the PDU Session Modification Request message and sets the operation code to "Save existing QoS rule" for each of the QoS rule identifier that is saved. The UE may do so after moving into NB-IoT. The network can then respond with the PDU Session Modification Command message as proposed above.

In certain examples, when the UE moves out of NB-IoT, the UE may autonomously resume using all saved QoS parameters. The SMF may also do the same after being notified that the UE has moved out of NB-IoT (e.g. into WB-EUTRA or NR).

In certain examples of the present disclosure, the above techniques may also be achieved by defining a new I E instead of using the QoS rules I E. For example, a new Saved QoS parameter context IF may be defined to list the QoS parameters that have been, or should be, saved In certain examples, the IE may contain any combination of the current QoS parameters that are listed above or that are defined in [2].

3. Handling QoS rules at the Establishment of a new PDU Session in Ni mode or PDN Connection in Si mode As indicated above, the UE in NB-1°T can only have, for each PDU session, a default QoS rule only. As such, no other non-QoS rules can exist. However, as errors can occur, the UE should check that this does not happen.

Therefore, in certain examples of the present disclosure, when the UE in NB-IoT receives a PDU Session Establishment Accept message, the UE should check for the following: * The UE should check if the QoS rules received contains the operation set to "Create new QoS rule", and optionally the DQR bit is not set to "the QoS rule is not the default QoS rule" (i.e. there is an operation to create a new QoS rule that is not a default QoS rule).

If the above occurs, the UE shall, after the completion of the current PDU session establishment procedure, send a PDU Session Modification Request message to delete each of the QoS rule that is not the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each QoS rule which is not a default QoS rule. That is, the UE locally deletes any rule that is not a default QoS rule, and does not report an error to the network.

Alternatively, the UE shall initiate the PDU session release procedure by sending the PDU Session Release Request message. For example, the UE may use an existing 5GSM cause or a new 5GSM cause as described herein.

* The UE should check if the flow description operation (in the QoS flow descriptions 1E) is set to "Create new QoS flow description", the request type is "initial request", and the QFI of the QoS flow description is not the same as the QFI that is associated with default QoS rule.

If the above occurs, the UE shall, after the completion of the current PDU session establishment procedure, send a PDU Session Modification Request message to delete each QoS flow description that has a ()F1 which is not the same as the QFI of the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each QoS flow description that has a QFI which is not the same as (or is not associated with) the OH of the default QoS rule. That is, the UE locally deletes all other additional QoS flow descriptions that have a ()F1 which is not the same as the QFI of the default QoS rule. A QoS flow description is associated with a QoS rule by the QFI. Since only a default QoS rule is allowed for each PDU session when the UE is in NB-IoT, then if the QoS flow description has a QFI which is not the same as the C)F1 of the default QoS rule the UE should not keep it. Examples of the present disclosure locally delete such QoS flow

description.

* The UE should check if there is at least one mapped EPS bearer operation (in the Mapped EPS bearer contexts IE if received) with the operation code set to: o "Create new EPS bearer" and the associated QFI corresponds to a QoS rule that is not the default QoS rule, o "Modify existing EPS bearer" and the associated QFI corresponds to a QoS rule that is not the default QoS rule.

If the above occurs, the UE shall, optionally after the completion of the current 5GSM procedure, send a PDU Session Modification Request message to delete each mapped EPS bearer context with a QFI that is not the same as the OH of the default QoS rule.

Alternatively, the UE does not diagnose an error and shall locally delete each mapped EPS bearer context with a C)F1 that is not the same as (or is not associated with) the QFI of the default QoS rule. That is, the UE locally deletes each mapped EPS bearer context with a QFI that is not the same as (or is not associated with) the QFI of the default QoS rule, and does not report an error to the network.

The above examples may also be applied when the UE is in Si mode for which the UE is proposed to verify the same or equivalent or corresponding errors on TFTs. QoS rules and QoS flow descriptions during any ESM procedure.

Summary of Certain Examples of the Present Disclosure The UE should preferably not send information that is related to an unsupported feature. Sending such information is not only useless for the network but is also inefficient as it will unnecessarily increase the message size and potentially increase power consumption when the UE is in low coverage areas. As described above, certain examples of the present disclosure provide techniques to avoid sending information that does not apply to the sending U E. Furthermore, the UE in NB-IoT may receive different QoS rule operations, or QoS flow description operations, or mapped EPS bearer context operations to create or modify existing rules, flow descriptions, or mapped EPS bearer contexts, respectively, where the QR of these parameters are not associated with the default QoS rule. Such parameters are not allowed to exist for a UE in NB-IoT (since only the default QoS rule can be available for the UE's PDU session) and there are currently no means to check for such errors and recover from them. On the other hand, certain examples of the present disclosure provide techniques to recover from such QoS errors.

In accordance with an example of the present disclosure, there is provided a method, for a UE, for establishing a data session, the method comprising: determining whether to provide an indication of a maximum data rate for the data session; if it is determined to provide the indication, transmitting, to a network entity, a data session establishment request including the indication; and if it is determined not to provide the indication, transmitting, to the network entity, a data session establishment request not including the indication.

In certain examples, the determining may comprise: determining to provide the indication if the UE supports transfer of data over the user plane (e.g. for uplink and/or for downlink); and determining not to provide the indication if the UE does not support transfer of data over the user plane (e.g. for uplink and/or for downlink).

In certain examples, the determining may comprise determining to provide the indication when in Si mode, after the first inter-system change from Si mode to Ni mode, the UE is operating in single-registration mode in the network supporting N26 interface, and if the UE supports data transfer over the user plane (i.e. the UE supports N3 data transfer).

In certain examples, the indication may be of format "TLV", and the indication may comprise a data structure including: (i) a first portion (e.g. first octet) containing an identifier (e.g. an Integrity protection maximum data rate 1E1), (ii) a second portion (e.g. second octet) containing a length of the indication (e.g. length of the integrity protection maximum data rate contents), (Hi) a third portion (e.g. third octet) containing a maximum data rate per UE for uplink (e.g. maximum data rate per UE for user-plane integrity protection for uplink), and (iv) a fourth portion (e.g. fourth octet) containing a maximum data rate per UE for downlink (e.g. maximum data rate per UE for user-plane integrity protection for downlink).

In certain examples, transmitting the data session establishment request not including the indication may comprise transmitting the data session establishment request including a value (e.g. predetermined value) indicating that the UE does not support transfer of data over the user plane.

In accordance with another example of the present disclosure, there is provided a method, for a UE, for establishing a data session, the method comprising: determining whether the UE supports transfer of data over the user plane; if the UE supports transfer of data over the user plane, transmitting, to a network entity, a data session establishment request including an indication of a maximum data rate for the data session; and if the UE does not support transfer of data over the user plane, transmitting, to the network entity, a data session establishment request including a value (e.g. predetermined value) indicating that the UE does not support transfer of data over the user plane.

In certain examples, the data session may be a PDU session, the indication may comprise an Integrity protection maximum data rate 1E, and the data session establishment request may comprise a PDU Session Establishment Request message.

In accordance with another example of the present disclosure, there is provided a method, for a network entity, for establishing a data session, the method comprising: receiving a data session establishment request; determining whether the data session establishment request includes a value (e.g. predetermined value) indicating that a UE does not support transfer of data over the user plane, or whether an indication of a maximum data rate for the data session is included in the data session establishment request; if the data session establishment request includes the value or does not include an indication of a maximum data rate, determining that the UE does not support user plane integrity protection, and optionally setting an integrity protection requirement as not needed for the UE.

In certain examples, the method may further comprise: forwarding, to a second network entity, the data session establishment request; and transmitting, to the second network entity, an indication (e.g. control plane only indication) that the UE does not support transfer of data over the user plane, whereby the second network entity (i) determines that integrity protection for the user plane associated with the data session is not required based on the indication that the UE does not support transfer of data over the user plane, and (ii) sets an integrity protection requirement as not needed for the UE.

In accordance with another example of the present disclosure, there is provided a method, for a UE and/or a first network entity (e.g. an SMF entity), for managing a data session in a network, wherein the data session is established for the UE and is associated with one or more QoS rules including a default QoS rule, the method comprising: in response to mobility of the UE from a first RAT into a second RAT (e.g. N B-loT RAT), deleting, at the UE and/or the first network entity, all QoS rules except for the default QoS rule.

In certain examples, the method may further comprise: setting a packet filter associated with the default QoS rule to match all filter for the uplink (and optionally for the downlink), whereby all traffic associated with the data session is mapped to the default QoS rule.

In accordance with another example of the present disclosure, there is provided a method, for a UE, for managing a data session in a network, wherein the data session is established for the UE and is associated with one or more QoS rules including a default QoS rule, the method comprising: in response to receiving a data session modification command from a network entity (e.g. an SMF entity) while the UE is in a second RAT (e.g. NB-IoT RAT), determining whether a condition, based on one or more QoS parameters (e.g. one or more of QoS rules, QoS flow descriptions, and mapped EPS bearer contexts) associated with the data session modification command, is satisfied.

In certain examples, the condition may comprise: there is a QoS rule specified in the data session modification command with a rule operation set to: "create new QoS rule" (and optionally the QoS rule is not the default QoS rule); and/or "modify existing QoS rule" (and optionally the operation is on a non-default QoS rule).

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session modification according to the data session modification command, transmitting a data session modification request message to delete each QoS rule that is not the default QoS rule; if the condition is satisfied, deleting each QoS rule that is not a default QoS rule without reporting an error to the network; and if the condition is satisfied, optionally after completing data session modification according to the data session modification command, transmitting a data session release request message to initiate a data session release procedure.

In certain examples, the condition may comprise: there is a QoS flow description specified in the data session modification command with a flow description operation set to: "create new QoS flow description" (and optionally the QoS flow identifier is not associated with the QoS flow identifier of the default QoS rule); and/or "modify existing QoS flow description" (and optionally the QoS flow identifier is not associated with the QoS flow identifier of the default QoS rule).

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session modification according to the data session modification command, transmitting a data session modification request message to delete each QoS flow description that has a OH that is not the same as the C)F1 of the default QoS rule; if the condition is satisfied, deleting, at the UE, each QoS flow description that has a QFI that is not the same as the OH of the default QoS rule, without reporting an error to the network; and if the condition is satisfied, transmitting a data session release request message to initiate a data session release procedure.

In certain examples, the condition may comprise: there is at least one mapped EPS bearer operation with the operation code set to: "create new EPS bearer" (and optionally the associated QFI corresponds to a QoS rule that is not the default QoS rule); and/or "modify existing EPS bearer" (and optionally the associated OH corresponds to a QoS rule that is not the default QoS rule).

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session modification according to the data session modification command, transmitting a data session modification request message to delete each mapped EPS bearer context with a C)F1 that is not the same as the C)F1 of the default QoS rule; if the condition is satisfied, deleting, at the UE, each mapped EPS bearer context with a QFI that is not the same as the OR of the default QoS rule, without reporting an error to the network; and if the condition is satisfied, transmitting a data session release request message to initiate a data session release procedure.

In certain examples, the data session modification request message may comprise information (e.g. generic or scenario-specific) indicating the reason for the data session modification request.

In accordance with another example of the present disclosure, there is provided a method, for a UE and/or a first network entity (e.g. an SMF entity), for managing a data session in a network, wherein the data session is established for the UE and is associated with one or more QoS rules including a default QoS rule, the method comprising: in response to mobility of the UE from a first RAT into a second RAT (e.g. NB-IoT RAT), or in response to receiving a data session modification message including a predetermined indication, saving, by the UE and/or the first network entity, one or more QoS parameters (e.g. one or more of QoS rules, QoS flow descriptions, and mapped EPS bearer contexts) associated with the data session.

In certain examples, the method may further comprise using, for the data session, the default QoS rule and any QoS parameters associated with the default QoS rule.

In certain examples, saving the QoS parameters may comprise saving (i) the default QoS rule and QoS parameters associated with the default QoS rule, and (ii) one or more QoS parameters that are not the default QoS rule or are not associated with the default QoS rule.

In certain examples, saving the QoS parameters may comprise saving a QoS parameter context and a corresponding QoS parameter context ID.

In certain examples, saving the QoS parameters may comprise saving a QoS parameter context per data session.

In certain examples, the QoS parameter context and the corresponding QoS parameter context ID may comprise: a list of QoS rule identifiers for each QoS rule and: for each QoS rule, an associated QoS flow description; for each QoS rule, an associated Mapped EPS bearer context; and a QoS parameter context ID corresponding to each QoS rule identifier.

In certain examples, the method may further comprise signalling, by the UE and/or the first network entity, support for saving QoS parameters.

In certain examples, the method may further comprise: in response to mobility of the UE from the second RAT into a RAT different from the second RAT, retrieving the saved QoS parameters, and using the retrieved QoS parameters for the data session.

In accordance with another example of the present disclosure, there is provided a method, for a UE, for managing a data session in a network, wherein the data session is established for the UE and is associated with one or more QoS rules including a default QoS rule, the method comprising: in response to receiving a data session establishment accept message from a network entity (e.g. an SMF entity) while the UE is in a second RAT (e.g. NB-IoT RAT), determining whether a condition, based on one or more QoS parameters (e.g. one or more of QoS rules, QoS flow descriptions, and mapped EPS bearer contexts) associated with the data session establishment accept message, is satisfied.

In certain examples, the condition may comprise: there is a QoS rule specified in the data session establishment accept message with a rule operation set to "create new QoS rule" (and optionally the QoS rule is not the default QoS rule).

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session establishment, transmitting a data session modification request message to delete each QoS rule that is not the default QoS rule; if the condition is satisfied, deleting each QoS rule that is not the default QoS rule without reporting an error to the network; and if the condition is satisfied, transmitting a data session release request message to initiate a data session release procedure.

In certain examples, the condition may comprise: (i) there is a QoS flow description specified in the data session establishment accept message with a flow description operation set to "create new QoS flow description", (ii) the request type is "initial request", and (iii) the an of the QoS flow description is not the same as the QFI associated with the default QoS rule.

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session establishment, transmitting a data session modification request message to delete each QoS flow description that has a QFI that is not the same as the an of the default QoS rule; if the condition is satisfied, deleting, at the UE, each QoS flow description that has a QFI that is not the same as the QFI of the default QoS rule, without reporting an error to the network; and if the condition is satisfied, transmitting a data session release request message to initiate a data session release procedure.

In certain examples, the condition may comprise: there is at least one mapped EPS bearer operation with the operation code set to: "create new EPS bearer' (and optionally the associated QFI corresponds to a QoS rule that is not the default QoS rule); and/or "modify existing EPS bearer" (and optionally the associated OH corresponds to a QoS rule that is not the default QoS rule).

In certain examples, the method may further comprise one or more of: if the condition is satisfied, after completing data session establishment, transmitting a data session modification request message to delete each mapped EPS bearer context with a QFI that is not the same as the QFI of the default QoS rule; if the condition is satisfied, deleting, at the UE, each mapped EPS bearer context with a OH that is not the same as the QFI of the default QoS rule, without reporting an error to the network; and if the condition is satisfied, transmitting a data session release request message to initiate a data session release procedure.

In accordance with another example of the present disclosure, there is provided a UE or network entity configured to operate according to a method of any of the above examples.

In accordance with another example of the present disclosure, there is provided a network comprising a UE and/or a network entity according to the preceding example.

In accordance with another example of the present disclosure, there is provided a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any of the above examples.

In accordance with another example of the present disclosure, there is provided a computer or processor-readable data carrier having stored thereon a computer program according to the preceding example.

Figure 2 is a block diagram of an exemplary network entity or UE that may be used in examples of the present disclosure. The skilled person will appreciate that a network entity may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and/or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

The entity or UE 200 comprises a processor (or controller) 201, a transmitter 203 and a receiver 205. The receiver 205 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 203 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 201 is configured for performing one or more operations, for example according to the operations as described above.

The techniques described herein may be implemented using any suitably configured apparatus and/or system. Such an apparatus and/or system may be configured to perform a method according to any aspect, embodiment, example or claim disclosed herein. Such an apparatus may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and/or method steps for implementing the techniques described herein. For example, an operation/function of X may be performed by a module configured to perform X (or an X-module). The one or more elements may be implemented in the form of hardware, software, or any combination of hardware and software.

It will be appreciated that examples of the present disclosure may be implemented in the form of hardware, software or any combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage, for example a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape or the like.

It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement certain examples of the present disclosure. Accordingly, certain example provide a program comprising code for implementing a method, apparatus or system according to any example, embodiment, aspect and/or claim disclosed herein, and/or a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium, for example a communication signal carried over a wired or wireless connection.

While the invention has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention, as defined by the appended claims.

Acronyms, Abbreviations and Definitions In the present disclosure, the following acronyms, abbreviations and definitions are used.

3GPP 3rd Generation Partnership Project 5G 5th Generation 5GC 5G Core 5GS 5G System 5GMM 5G Mobility Management 5GSM 5G Session Management AMF Access and Mobility Management Function C Conditional CN Core Network DNN Data Network Name DQR Default QoS Rule indicator DRB Data Radio Bearer E-UTRAN Evolved Universal Terrestrial Radio Access Network EPC Evolved Packet Core EPS Evolved Packet System ESM EPS Session Management EUTRA Evolved Universal Terrestrial Radio Access H-SMF Home SMF ID Identifier; Identity IE Information Element 1E1 Information Element Identifier loT Internet of Things IPv4 Internet Protocol version 4 IPv4v6 Internet Protocol Dual Stack IPv6 Internet Protocol version 6 Mandatory MME Mobility Management Entity Ni Interface between UE and AMF N3 Interface between RAN and UPF N11 Interface between AMF and SMF N26 Interface between MME and AMF NAS Non Access Stratum NB Narrowband NR New Radio NSSAI Network Slice Selection Assistance Information 0 Optional PDU Protocol Data Unit QFI QoS Flow Identifier QoS Quality of Service RAN Radio Access Network RAT Radio Access Technology Si mode a mode of a UE that operates with a functional division that is in accordance with the use of an Si interface between the radio access network and the core network SM Session Management SMF Session Management Function S-NSSAI Single NSSAI TAI Tracking Area Identity TAU Tracking Area Update TFT Traffic Flow Template TLV Type, Length and Value TLV-E TLV-Extended

TS Technical Specification

TV Type and Value UDM Unified Data Management UE User Equipment UP User Plane UPF User Plane Function V Value VPLMN Visited Public Land Mobile Network WE Wdeband

Claims

Claims 1. A method, for a UE, for establishing a data session, the method comprising: determining whether the UE supports transfer of data over the user plane; if the UE supports transfer of data over the user plane, transmitting, to a network entity, a data session establishment request including an indication of a maximum data rate for the data session; and if the UE does not support transfer of data over the user plane, transmitting, to the network entity, a data session establishment request including a value (e.g. predetermined value) indicating that the UE does not support transfer of data over the user plane.
2. A method according to claim 2, wherein: the data session is a PDU session, the indication comprises an Integrity protection maximum data rate 1E, and the data session establishment request comprises a PDU Session Establishment Request message.
3. A method, for a network entity, for establishing a data session, the method comprising: receiving a data session establishment request; determining whether the data session establishment request includes a value (e.g. predetermined value) indicating that a UE does not support transfer of data over the user plane, or whether an indication of a maximum data rate for the data session is included in the data session establishment request; if the data session establishment request includes the value or does not include an indication of a maximum data rate, determining that the UE does not support user plane integrity protection.
4. A method according to claim 3, further comprising: forwarding, to a second network entity, the data session establishment request; and transmitting, to the second network entity, an indication (e.g. control plane only indication) that the UE does not support transfer of data over the user plane, whereby the second network entity (i) determines that integrity protection for the user plane associated with the data session is not required based on the indication that the UE does not support transfer of data over the user plane, and (ii) sets an integrity protection requirement as not needed for the UE.
5. A UE configured to operate according to a method of claim 1 or 2.
6. A network entity configured to operate according to a method of claim 3 or 4.
7. A network comprising a UE according to claim 5 and a network entity according to claim 6.
8. A computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any of claims 1 to 4.
9. A computer or processor-readable data carrier having stored thereon a computer program according to claim 8.