GB2622134A

GB2622134A - Enhancements for UE - satellite access

Info

Publication number: GB2622134A
Application number: GB2310418.5A
Authority: GB
Inventors: Kumar Lalith; Watfa Mahmoud; Khirallah Chadi
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2022-08-08
Filing date: 2023-07-06
Publication date: 2024-03-06

Abstract

A method for a UE in a communications network using a satellite to access the network (i.e. a non-terrestrial network (NTN)) comprising verifying whether or not a Non Access Stratum (NAS) procedure between the UE and the network via the satellite can be completed before a start of an unavailability period of the satellite (e.g. a period of discontinuous coverage). The NAS procedure may comprise any of a registration procedure, a mobility registration update procedure, a NAS request procedure, an attach procedure, a tracking area update procedure, a service request procedure, a NAS mobility management procedure, a NAS session management procedure, NAS signalling, a NAS message. The method may comprise a step of the UE only initiating the NAS procedure when it verifies there is enough time for it to be completed before the start of the unavailability period. The verification may be based on satellite flyover time. The verification may comprise verifying there is enough time for both the completion of the NAS procedure and for the UE to be in a state which permits the start of the NAS procedure. Also provided is a network for performing the method.

Description

Enhancements for UE -Satellite Access

BACKGROUND

Field

Certain examples of the present disclosure provide various techniques relating to enhancements for UE -satellite access for example within 3rd Generation Partnership Project (3GPP) 5th Generation (5G) communication networks using such access.

Description of the Related Art

The Yd Generation Partnership Project (3GPP) is developing solutions for the use of satellite access for connecting UEs, such as loT devices, to core networks, such as the evolved packet core (EPC).

One of the related aspects of this satellite use is discontinuous coverage (DC), in which a satellite's coverage is not always available for a UE, and hence it's satellite access is discontinuous. The lack of availability of satellite coverage for a UE is due to the movement of the satellite around the planet. When the satellite is near the UE, the UE will have coverage from the satellite. When the satellite is moving around the planet, a certain time being required for a full circle to be made, the UE will not have coverage from the satellite. When the satellite is again near the UE, the UE will have coverage from the satellite. In the presence of the satellite, and hence coverage, the concept of fly-over time is discussed which is basically the duration of time for which coverage is available to the UE. As an example, a satellite may take hours (10hrs, as an example) to go around the Earth at a certain orbit or distance. A satellite may have a fly-over time for a UE on Earth of only minutes (2mins, as an example) and the UE on Earth will only detect coverage every 10hrs.

Additionally, when using satellite communication, a UE will not be able to send any message if it does not have the satellite location or position. The time needed to do so is referred to as Time To First Fix (TTFF). The duration of TTFF depends on the state of the UE receive function, which may be one of three states: cold, warm, or hot. The 3GPP RAN2 working group has assumed certain example values, such that from a cold state, the global navigation satellite system (GNSS) fix can take up to 100s, from a warm state, 50s and from hot start, 2s.

It should be noted that when a UE is using satellite access, the non access stratum (NAS) timers that guard the NAS procedures are extended, so as to give enough time for lower layer transmissions of the UE to succeed and for a response to arrive at the UE from a message recipient. For example, the timer T3517 (in Ni mode) for the service request procedure (for which, for example, the UE sends the Service Request message) is 15s when the UE is not using satellite access. However, when satellite access is used, this timer is set to 27s. This is because the lower layer transmissions in satellite access are expected to require more time to transmit a message. Setting the timer to 15s would lead to an early failure of the NAS procedure, even if the response message may well be received a few seconds after the 15s time mark. To avoid this, the NAS timers have been extended in TS 24.301 and IS 24.501.

The NAS timers may have different names in Si mode compared to Ni mode and may also have different values depending on whether the UE is using narrow band or wide band, etc. The following problems have been identified. Consider the following example: assume a satellite's flyover time starts at Ti and it is expected to last until Ti + 60s. At time T2, which is, say, equal to Ti + 50s, i.e. 50s into the flyover time, the satellite is expected to provide coverage for an additional 10s. A UE in idle mode may have data or signalling to send at T2. This means that the UE only has 10s left to complete the service request procedure, for which the NAS timer is to be set at 27s. The remaining 10s of flyover time would likely be insufficient for the completion of the NAS procedure. The NAS procedure will therefore almost be guaranteed to be unsuccessful due to lack of enough coverage time. A failed NAS procedure means that the UE would have wasted power in the NAS procedure. Note that, as mentioned earlier, the NAS timers may be different in Si mode and also the timer values may be different and can be longer than the example used here.

The UE battery life is very important to preserve. The UE may need to perform a communication process before the start of the DC. However, if the UE performs a communication process at the time when a DC event starts (i.e. when the satellite becomes unavailable), then the UE will waste power unnecessarily because the process will not complete before the satellite coverage is discontinued. This will have negative impact on the UE battery, since the power used for communication process is wasted. Note that even if the UE is able to send a message in the communication process, there may not be enough time for the network to complete the communication process. This will also unnecessarily cause signaling to increase in the communication network.

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 respect 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. Embodiments or examples disclosed in the description and/or figures falling outside the scope of the claims are to be understood as examples useful for understanding the present invention.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings.

According to one aspect of the disclosure there is provided a method for a UE in a communications network using a satellite to access the network comprising verifying if a communication process between the UE and the network via the satellite can be completed before a start of an unavailability period of the satellite or cannot be completed before a start of an unavailability period of the satellite.

The UE may only initiate the communication process when it verifies that there is enough time for the communication process to be completed before the start of the unavailability period of the satellite.

The communication process may comprise a non access stratum, NAS, procedure.

The UE may only trigger the NAS procedure when it verifies that there is enough time for the procedure to be completed before the start of the unavailability period of the satellite and loss of satellite coverage for the UE.

The UE may trigger the NAS procedure during a time range for which the procedure can be completed before the start of the unavailability period of the satellite and loss of satellite coverage for the UE The NAS procedure may be triggered during a time range before the UE loses coverage. The UE may trigger the NAS procedure early enough such that the procedure, under normal conditions, is able to complete before the start of a satellite unavailability period.

Verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite may comprise verifying if the NAS procedure can or cannot be completed before a related NAS timer expires.

Verifying if the NAS procedure can or cannot be successfully completed before the related NAS timer expires may comprise the UE receiving an expected NAS response message before the related NAS timer expires.

The UE would most likely verify a remaining time also based on the NAS timer of the NAS procedure and use the remaining time as a basic method to compare if there is enough time or not for the NAS procedure.

The NAS procedure may comprise any of a registration procedure, a mobility registration update procedure, a NAS request procedure, a service request procedure, a NAS mobility management procedure, a NAS session management procedure, NAS signalling, a NAS message.

Verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite may comprise verifying that there is a minimum time duration before the start of the unavailability period.

When the UE verifies that there is the minimum time duration, the UE may initiate the communication process and when the UE verifies that there is not the minimum time duration, the UE may not initiate the communication process even if a remaining flyover time of the satellite is not zero or satellite coverage is still available to the UE or the unavailability period has not yet started.

Verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite may use at least one time value.

A first time value may comprise a remaining time period between a current time and the start of the unavailability period, a second time value may comprise a time period for completion of the communication process and verifying that the communication process can be completed before the start of the unavailability period of the satellite may comprise determining that the first time value comprising the remaining time period is greater than the second time value comprising the time period for completion of the communication process.

The time period for completion of the communication process may comprise a time period between a start of a communication procedure and an end of the communication procedure of the communication process and optionally a time period for the UE to be in a state which permits start of the communication procedure.

The UE may be in any of Si mode, Ni mode.

According to a second aspect of the disclosure there is provided a UE in a communications network using a satellite to access the network, configured to carry out the method of the first aspect.

According to a third aspect of the disclosure there is provided a communications network comprising a UE according to the second aspect and a core, the UE using the method according to the first aspect to access a satellite to access the core.

The communication process may be a process initiated by the UE. The communication process may be a process initiated by the UE on receipt of a message from the network.

The communication process may comprise a NAS communication procedure. The communication process may comprise initiation of a NAS procedure. The communication process may comprise completion of a NAS procedure.

Completion of the communications process before the start of the unavailability period of the satellite may comprise the UE transmitting a message to the network. Completion of the communications process the start of the unavailability period of the satellite may further comprise the UE receiving an expected response message from the network.

Verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite may use at least one time value. The time value may comprise a time period before a NAS timer expires. The time value may comprise a remaining time period between a current time and the start of the unavailability period. The time value may comprise a time period for completion of the communication process.

Verifying that the communication process can be completed before the start of the unavailability period of the satellite may comprise determining that the time value comprising the remaining time period is greater than the time value comprising the time period for completion of the communication process.

The time value may comprise a minimum time period. Verifying that the communication process can be completed before the start of the unavailability period of the satellite may comprise determining that the time value comprising the remaining time period is greater than or equal to the time value comprising the minimum time period.

The minimum time period may be received by the UE from the network. The minimum time period may be part of the UE subscription information. The minimum time period may be determined by the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of an exemplary UE that may be used in examples of the present

disclosure, and

Figure 2 is a flow chart illustrating the method of the invention when the communication process comprises sending a NAS message.

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.

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 these examples or to 3GPP 5G, 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 skilled person will appreciate that the techniques disclosed herein may be applied in any existing or future releases of 3GPP 5G NR or any other relevant standard.

For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network.

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, entities and/or messages may be added to the examples disclosed herein.

* One or more non-essential elements, entities and/or messages 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 may be modified, if possible, in alternative

examples.

* The transmission of information between network entities is not limited to the specific form, type and/or order of messages described in relation to the examples disclosed herein.

For a UE in a communications network using a satellite to access the network, a method of the present disclosure comprises verifying if a communication process between the UE and the satellite can be completed before a start of an unavailability period of the satellite or cannot be completed before a start of an unavailability period of the satellite.

The above is a general UE behaviour of the present disclosure. The following describes details that can be used to achieve the above aspect. These details are examples only and they may be used in any combination or order.

The method at least alleviates the problem of wasted power and unnecessary signalling overhead between the UE and the network, as a result of incomplete communication procedures.

Figure 1 is a block diagram of an exemplary UE that may be used in examples of the present disclosure. The skilled person will appreciate that the network entity illustrated in Figure 1 may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

The 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 entities of the communications network and the satellite. The transmitter 203 is configured for transmitting one or more messages to one or more other entities of the communications network and the satellite. The processor 201 is configured for performing operations as described below.

A flyover time of the satellite may be a time period within which the satellite provides coverage for the UE. The expiration of the flyover time of the satellite may be a time at which a discontinuous coverage (DC) event occurs i.e. a start of an unavailability period of the satellite.

The method may comprise the UE verifying that the communication process can be completed and then initiating the communication process.

The method may comprise the UE verifying that the communication process cannot be completed and then determining not to initiate the communication process. This may be the case even if satellite access/coverage is still available, or even if the remaining satellite flyover time is not zero, or even if a next satellite DC event i.e. a next unavailability period of the satellite has not yet started.

The method may comprise the UE verifying that the communication process cannot be completed and any of keeping UE access stratum functions deactivated, deactivating UE access stratum function, remaining in idle mode, entering idle mode optionally by the UE locally releasing its NAS signalling connection, staying in current mode, remaining in power saving mode, activating power saving mode, starting a timer to guard the release of the NAS signalling connection by the network (e.g. starting T3540 in 5G or the equivalent in LTE e.g. T3440) and after the expiry of which the UE may then enter idle mode.

The communication process may be a process initiated by the UE. The communication process may be a process initiated by the UE on receipt of a message from the network. The message from the network may comprise a page. The UE may receive a page and verify whether a response to the page can be completed before a start of an unavailability period of the satellite or cannot be completed before a start of an unavailability period of the satellite.

The communication process may comprise a NAS procedure. The communication process may comprise initiation of a NAS procedure. The communication process may comprise completion of a NAS procedure. The NAS procedure may be a NAS message. The NAS message may be a NAS request. The NAS message may be NAS signalling. The NAS signalling may be for any of sending data, requesting resources for data. The communication procedure may be a RRC procedure. The RSS procedure may be a RSS message.

Completion of the communication process before a start of an unavailability period of the satellite may comprise the UE transmitting a message to the network. Completion of the communication process before a start of an unavailability period of the satellite may further comprise the UE receiving an expected response message from the network.

Completion of a communication process comprising a NAS procedure before a start of an unavailability period of the satellite may comprise transmission of a NAS message to the network. Completion of a communication process comprising a NAS procedure before a start of an unavailability period of the satellite may further comprise receiving an expected response message from the network. The expected response message may be a NAS response message.

In one embodiment, the NAS procedure may be a Registration Request message and the expected response message may be a NAS response message comprising any of a Registration Accept, a Registration Reject. In another embodiment, in LTE (i.e. Si mode), the NAS procedure may comprise a Service Request message and the expected response message may be any NAS message, such as any of a Security Mode Command message, indication from UE lower layers that bearers have been established, or any other method that is known to be an indication of the success of the NAS procedure in question.

The method may comprise verifying if the communication process can or cannot be completed before a start of an unavailability period of the satellite by using at least one time value.

The time value may comprise a time period before a NAS timer expires.

The time value may comprise a remaining time period, T_rem, between a current time and a start of an unavailability period. This is basically the time period in which the satellite coverage remains available and hence the UE can (at least in theory) initiate the communication process. The method may comprise determination of the start of an unavailability period. This may be equivalent to determination of a start time of a next DC event.

The time value may comprise a time period for completion of the communication process.

The method may comprise verifying that the communication process can be completed before a start of an unavailability period of the satellite by determining that the time value comprising the remaining time period is greater than the time value comprising the time period for completion of the communication process.

The time period for completion of the communication process may comprise a time period between a start of a communication procedure of the communication process and an end of the communication procedure. The communication procedure may comprise transmission of a message by the UE. The time period for completion of the communication process may further comprise a time period for the UE to be in a state which permits start of a communication procedure of the communication process.

The time period for the UE to be in a state which permits start of a communication procedure of the communication process may be zero. This may occur if the UE is already in a state which permits the UE to start the communication procedure.

The method may comprise determination of whether the UE is in a state which permits start of the communication procedure. This may comprise any of: * the UE's lower layers are such that they are ready to start the communication procedure without needing any GNSS fix time, or without needing Time To First Fix (TTFF), * the UE is in 5GMM-CONNECTED mode (or EMM-CONNECTED mode), or 5GMMCONNECTED mode with RRC inactive indication, * the UE is in 5GMM-IDLE mode (or EMM-IDLE mode), or in 5GMM-IDLE mode with suspend indication (EMM-IDLE mode with suspend indication), * the UE is in RRC-CONNECTED state or RRC-INACTIVE state, * the UE is in RRC-IDLE state, Any combinations of the above may apply, however what is important is that the UE's lower layers do not need additional time to be ready to start the communication procedure.

The time period for the UE to be in a state which permits start of a communication procedure of the communication process may be non-zero. The method may comprise determining the non-zero time period for the UE to be in a state which permits start of the communication procedure.

The UE may not be in a state which permits start of the communication procedure as the UE needs time for the lower layers thereof to start the communication procedure. For example, the UE may need a non-zero time period to start the communication procedure due to GNSS fix time (or Time To First Fix) due to the UE being, e.g. in cold state, warm state, hot state, etc. The UE should consider the time required by the lower layers of the UE to be in a certain state which permits the communication procedure, which may comprise transmission of a message. For example, the UE may consider the time required to enter a RRC-CONNECTED state from any state that the UE may currently be in e.g. a RRC-IDLE state. As such, when determining if there is sufficient time to complete the communication process, e.g. sending a NAS message or initiating a NAS procedure, the UE may consider at least one aspect such as those listed herein e.g. time to fix, time to be in a RRC-CONNECTED state, remaining time before a start of an unavailability period of the satellite, etc. The time value may comprise a minimum time period, T_min.

The method may comprise verifying that the communication process can be completed before a start of an unavailability period of the satellite by determining that the time value comprising the remaining time period is greater than the time value comprising the minimum time period. The method may comprise verifying that the communication process can be completed before a start of an unavailability period of the satellite by determining that the time value comprising the remaining time period is equal to the time value comprising the minimum time period.

When this is the case, the UE can initiate the communication process.

The method may comprise verifying that the communication process cannot be completed before a start of an unavailability period of the satellite by determining that the time value comprising the remaining time period is less than the time value comprising the minimum time period.

When this is the case, the UE will not initiate the communication process.

The above proposals may apply to a UE in any NAS mode e.g. idle mode, connected mode, idle mode with suspend indication, or connected mode with RRC inactive indication (which only applies to Ni mode i.e. 5GS).

It should be noted that: * a NAS idle mode may refer to: EMM-IDLE mode (in Si mode), or 5GMM-IDLE mode (in Ni mode), * a NAS idle mode with suspend indication may refer to: EMM-IDLE mode with suspend indication, or 5MM-IDLE mode with suspend indication, * a NAS connected mode may refer to: EMM-CONNECTED mode, or 5GMMCONNECTED mode.

* a NAS connected mode with RRC inactive indication may refer to: 5GMMCONNECTED mode with RRC inactive indication.

The above proposals also apply to a UE in Si mode (i.e. EPS) or to a UE in Ni mode (i.e. 5GS). For the proposals herein, the UE may be in state of the REGISTERED or DEREGISTERED state in either Si mode or Ni mode. The UE may also be in any substate of the REGISTERED or DEREGISTERED state (in either Ni mode or S1 mode).

Referring to Figure 2, a flow chart illustrates the above proposals when the communication process includes sending a NAS message.

When the time value comprising the minimum time period, T_min, is used in the method, the UE should ensure that the minimum time period is known and/or well determined for the purpose of deciding if the communication process can be completed or not.

The minimum time period may comprise a value of a NAS timer which is associated with transmission of a communication procedure of the communication process comprising a NAS message, or to a fraction of the value of the NAS timer which is associated with the transmission of the NAS message. The minimum time period may be a predetermined minimum time period. Optionally the predetermined minimum time period may be a time period associated with a mobility management message. Optionally the predetermined minimum time period may be a time period associated with a session management message.

The minimum time may also mean that the UE should also consider the time required by the lower layers to be in a certain state which permits the transmission of a message. For example, the UE may consider the time required to enter RRC-CONNECTED state from any state that the UE may currently be in e.g. RRC-IDLE state. As such, when determining if there is sufficient time to send a NAS message or initiate a NAS procedure, the UE may consider at least one aspect such as those listed herein e.g. time to fix, time to be in RRC-CONNECTED state, remaining time before a start of an unavailability period of the satellite, etc. The minimum time period may be received by the UE from the network. The minimum time period may be received by the UE from the network in a NAS message. The NAS message may comprise any of a Registration Accept, an Attach Accept, a Configuration Update Command, a Service Accept, a PDU Session Establishment Accept message, any similar message that is used in EPS. The NAS message may be any new or existing message. The NAS message may be either a NAS mobility management message or a NAS session management message or both. The minimum time period may be received by the UE from the network in any of a container, a policy container, a part of steering information, a part of roaming information.

In another possibility, the minimum time period received by the UE from the network may be associated with any of a NAS mobility management message, NAS mobility management procedure, a NAS session management message or procedure. It is also possible the minimum time period received by the UE from the network may be associated with a particular message type such as a Registration Request, a Tracking Area Update Request, a Service Request.

The network may determine the minimum time period based on implementation details, and/or based on knowledge of the discontinuous coverage time period, and/or based on consideration of a GNSS fix time where this time may be the time required for the UE's lower layers to be ready for an access attempt on the satellite.

The minimum time period may be received by the UE from the network using any information element (1E) or NAS message. The network may do so optionally when: * the UE indicates support for handling the minimum time period, or indicates support for behaving as described herein, or indicates a new capability that is understood to imply a UE behaviour in accordance with the proposals herein. A UE which behaves in accordance with the proposals herein should send such an indication to the network (e.g. MME, SMF, AMF, etc) using any IE or any NAS message such as a 5GMM capability IE in a Registration Request message, or any other similar IE that is sent in any EPS NAS message, * subscription information of the UE indicates that the UE supports this feature, or supports behaving in accordance with the proposals herein, or when the subscription information contains at least one minimum time value for the UE.

When the UE receives the minimum time period, where this may be per NAS mobility management, or NAS session management, or both, the UE uses the minimum time period as described earlier. Optionally, the UE may store the determined value until a new value is received or determined. Any new determined value may replace an existing determined and/or stored value in the UE.

If the minimum time period is per NAS procedure type, where the procedure may be related to either a NAS mobility management procedure or a NAS session management procedure, or both, or the minimum time period is per NAS message type, then the UE should act as follows: if the UE has a NAS procedure to initiate, then when verifying whether the UE should initiate the procedure or not (as per the proposals herein), then the UE should use the minimum time period that is associated with the NAS procedure or message, if such an association exists. Once the minimum time period has been determined, then the UE uses the minimum time period to determine whether it can initiate the NAS procedure as described herein.

The remaining time period may be received by the UE from the network. The remaining time period may be received by the UE from the network as described above with reference to the minimum time period.

The network may provide a timer value to the UE which is then used to determine if there is sufficient time for completion of the communication process. For example, the UE may determine that * there is sufficient time if a remaining time period of a flyover time, i.e. before a start of an unavailability period of the satellite, is larger (or optionally equal to or larger) than the timer value received by the UE, * there is not sufficient time if a remaining time period of a flyover time, i.e. before a start of an unavailability period of the satellite, is smaller (or optionally equal to or smaller) than the timer value received by the UE.

The minimum time period may be part of UE subscription information. The minimum time period may be one value regardless of the NAS procedure, or may be per procedure or per message of the communication process, as described above. The network e.g. AMF and/or SMF, may obtain the minimum time period from the UE subscription information (e.g. from the UDM or HSS). Once obtained, the network may provide the minimum time period to the UE using the means explained above. The minimum time period may also be sent using any of a NAS message, a container, a policy container, a part of steering information, a part of roaming information.

The minimum time period may be provided to the UE by the HPLMN. The minimum time period may be provided to the UE directly using a container sent by the HPLMN in a secured manner. Once received in the UE, the UE uses the minimum time period as described herein.

The minimum time period may be determined by the UE. In one possibility, the minimum time period, which may or may not be associated with a specific NAS procedure/message as of the communication process described above, may be configured in the UE. The UE uses this preconfigured information to determine the minimum time period and uses the minimum time period as described herein.

The UE may store the minimum time period. The UE may continue to store the minimum time period if it is using a network access that is not the satellite access, or after the UE switches off, or after the UE deregisters from the PLMN, or changes a PLMN. Alternatively, the minimum time period may be deleted for any of the events listed and a new minimum time period may be used per PLMN once the UE registers to the PLMN. The minimum time period may be per PLMN or may apply for all PLMNs. The minimum time period may only apply for satellite access.

The proposals above may also apply to the remaining time period.

The UE may be configured to carry out the method when any of the following occurs, in any order or combination: * the UE is preconfigured to carry out the method, * the network indicates its support for the UE to carry out the method, where this support may be an explicit indication or an implicit indication e.g. by fact that the network provides the remaining time period or the minimum time period to the UE, * a user manually changes the settings on the UE to carry out the method.

Note that the same methods proposed herein may also be used to configure the UE to stop operating as described herein.

Certain examples of the present disclosure provide 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 example, embodiment, aspect and/or claim disclosed herein.

Certain examples of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to the preceding 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. Such an apparatus/device/network entity 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). Certain examples of the present disclosure may be provided in the form of a system (e.g. a network) comprising one or more such apparatuses/devices/network entities, and/or a method therefor. For example, in the following examples, a network may include one or more IAB nodes.

It will be appreciated that examples of the present disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the present disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and/or apparatus in accordance with any aspect, claim, example and/or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program.

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 disclosure.

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 examples disclosed herein.

Throughout the description and claims, the words "comprise", "contain" and "include", and variations thereof, for example "comprising", "containing" and "including", means "including but not limited to", and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, functions, characteristics, and the like.

Throughout the description and claims, 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, language in the general form of "X for Y" (where Y is some action, process, function, activity or step and X is some means for carrying out that action, process, 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, functions, characteristics, and the like, described in conjunction with a particular aspect, embodiment, example or claim are to be understood to be applicable to any other aspect, embodiment, example or claim disclosed herein unless incompatible therewith.

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.

Abbreviations/Definitions In the present disclosure, the following abbreviations and definitions may be used.

3GPP 3rd Generation Partnership Project 5G 5th Generation 5GC 5G Core AMF Access and Mobility Management Function DC Discontinuous Coverage DU Distributed Unit EPC Evolved Packet Core EMM Enterprise Mobility Management GNSS Global Navigation Satellite System GPRS General Packet Radio Service HSS Home Subscriber Server loT Internet of Things LTE Long Term Evolution MME Mobility Management Entity MRU Mobility Registration Update NAS Non Access Stratum NR New Radio PDU Protocol Data Unit PLMN Public/Private Land Mobile Network RAN Radio Access Network RAN2 Radio layer 2 and Radio layer 3 Working Group RRC Radio Resource Control SMF Session Management Function TTFF Time To First Fix UE User Equipment

Claims

CLAIMS1. A method for a UE in a communications network using a satellite to access the network comprising verifying if a communication process between the UE and the network via the satellite can be completed before a start of an unavailability period of the satellite or cannot be completed before a start of an unavailability period of the satellite.
2. A method according to claim 1 in which the UE only initiates the communication process when it verifies that there is enough time for the communication process to be completed before the start of the unavailability period of the satellite.
3. A method according to claim 1 or claim 2 in which the communication process comprises a Non Access Stratum, NAS, procedure.
4. A method according to claim 3 in which the UE only triggers the NAS procedure when it verifies that there is enough time for the procedure to be completed before the start of the unavailability period of the satellite and loss of satellite coverage for the UE
5. A method according to claim 3 or claim 4 in which the UE triggers the NAS procedure during a time range for which the procedure can be completed before the start of the unavailability period of the satellite and loss of satellite coverage for the UE.
6. A method according to any preceding claim in which verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite comprises verifying if the NAS procedure can or cannot be completed before a related NAS timer expires
7. A method according to claim 6 in which verifying if the NAS procedure can or cannot be successfully completed before the related NAS timer expires comprises the UE receiving an expected NAS response message before the related NAS timer expires.
8. A method according to any of claims 3 to 7 in which the NAS procedure comprises any of a registration procedure, a mobility registration update procedure, a NAS request procedure, an attach procedure, a tracking area update procedure, a service request procedure, a NAS mobility management procedure, a NAS session management procedure, NAS signalling, a NAS message.
9. A method according to any preceding claim in which verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite comprises verifying that there is a minimum time duration before the start of the unavailability period.
10. A method according to claim 9 in which when the UE verifies that there is the minimum time duration, the UE initiates the communication process and when the UE verifies that there is not the minimum time duration, the UE does not initiate the communication process even if a remaining flyover time of the satellite is not zero or satellite coverage is still available to the UE or the unavailability period has not yet started.
11. A method according to any preceding claim comprising verifying if the communication process can or cannot be completed before the start of the unavailability period of the satellite by using at least one time value.
12. A method according to claim 11 in which a first time value comprises a remaining time period between a current time and the start of the unavailability period, a second time value comprises a time period for completion of the communication process and verifying that the communication process can be completed before the start of the unavailability period of the satellite comprises determining that the first time value comprising the remaining time period is greater than the second time value comprising the time period for completion of the communication process.
13. A method according to claim 12 in which the time period for completion of the communication process comprises a time period between a start of a communication procedure and an end of the communication procedure of the communication process and optionally a time period for the UE to be in a state which permits start of the communication procedure.
14. A method according to any preceding claim in which the UE can be in any of Si mode, Ni mode.
15. A UE in a communications network using a satellite to access the network, configured to carry out the method according to any of claims 1 to 14.
16. A communications network comprising a UE according to claim 15 and a core, the UE using the method according to any of claims 1 to 14 to access a satellite to access the core.