Providing Neighbour Cell Information in Non-Terrestrial Network

Abstract

A method, for a first cell (e.g. a serving cell), for providing neighbour cell information (e.g. ephemeris information) of a second cell (e.g. a neighbouring cell), wherein the second cell is a Non Te

Description

BACKGROUND Field Certain examples of the present disclosure provide one or more techniques for providing neighbour cell information in a Non Terrestrial Network (NTN). For example, certain examples of the present disclosure provide one or more techniques for providing neighbour cell information in a 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) NTN. Description of the Related Art One of the areas currently under development in 3GPP 5G wireless technology is support for non-terrestrial networks (NTNs). An NTN is a network in which one or more nodes (e.g. a Next Generation Radio Access Network (NG-RAN) node) are provided by a non-terrestrial infrastructure, for example a satellite or High Altitude Platform Station (HAPS). Advantages of using an NTN include (i) extending coverage to regions, such as remote areas, with limited or no coverage from more traditional terrestrial networks, (ii) providing continuous coverage in the event of inoperability of traditional terrestrial networks, such as during natural disasters, and (iii) enhancing overall reliability, resilience and capacity when used in conjunction with existing terrestrial networks. A satellite network implementing a network node provides coverage through one or more radio beams forming a “footprint” on the surface of the Earth defining a coverage area or cell. An NTN cell may be Earth-moving (i.e. moving over the Earth’s surface according to the motion of the satellite, for example in the case of a Lower Earth Orbit (LEO) satellite), Earth-fixed (i.e. a fixed area of the Earth’s surface, for example in the case of a Geosynchronous Equatorial Orbit (GEO) satellite) or quasi-Earth-fixed (i.e. a fixed area of the Earth’s surface but is maintained for only a limited time as the satellite passes by). Internet of Things (loT) NTN was a 3GPP study and work item in 3GPP Release 17 (RP-202689, RAN#90 December 2020) to provide NTN access for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) loT devices (e.g. Narrowband (NB)-loT and Long Term Evolution Machine Type Communication (LTE-M), including enhanced Machine Type Communication (eMTC)). As noted in 3GPP RP-202689, loT operation is critical in remote areas with low / no cellular connectivity for many different industries. The capabilities of NB-loT and eMTC are a good fit for many applications but some applications may require satellite connectivity to provide coverage beyond terrestrial deployments. NR NTN was a work item in Release 17 to specify adaptation to allow NR to function over NTN (RP-211557, RAN#91-e March 2021). Following the work items in Release 17 there were work items to enhance NR NTN (RP-220953, RAN#95-e March 2022) and loT NTN (RP-220979, RAN#95-e March 2022) in Release 18. Due to the movement of satellites in a non-stationary orbit (e.g. LEO), the cells that a UE see will be moving (i.e. Earth-moving cells). This results in frequent UE handover from one cell to another, and this handover of service will happen constantly. In view of this, mobility is one of the key issues in both NR NTN and loT NTN. Overview of NTN System Information As NTN has a number of NTN-specific information elements that are only required when accessing an NTN cell, and also due to the relatively large information elements, it was agreed that new System Information Blocks (SIBs) are needed. In NR NTN, SIB19 contains the required information to access an NTN cell: ------------------------------3GPPTS 38.331 V17.2.0------------------------------ SIB19 SIB19 contains satellite assistance information for NTN access. SIB19 information element SIB19—rl7 ::= SEQUENCE ( ntn-Config-rl7 t-Service-rl7 referenceLocation-rl7 distanceThresh-rl7 ntn-NeighCelIConfigList-r17 '2 J .1 e-E ' f •••• 2 2. lateNonCriti calExtension - - -1- '• f [ [ ntn-NeighCelIConfigListExt-vl7 2 0 J J } NTN-NeighCellConfigList-rl7 ::= NeighCellConfig-rl7 NTN-NeighCellConfig-rl7 ::= ntn-Config-r!7 NTN-Config-rl7 INTEGER (0..549755813887) ReferenceLocation-rl7 1LGEGER(O..65525) NTN-NeighCelIConfigList-rl7 NTN-NeighCelIConfigList-rl7 ( CUE (1. .maxCellNTN-rl7 ) ) OF NTN- EEQ’JENCE { NTN-Config-rl7 carrierFreq-rl7 physCell!d-rl7 ARFCN-ValueNR PhysCellld SIB19 field descriptions ; distanceThresh i Distance from the serving cell reference location and is used in location-based measurement initiation in i RRC IDLE and RRC INACTIVE, as defined in TS 38.304

[20] , Each step represents 50m. i ntn-Config i Provides parameters needed for the UE to access NR via NTN access such as Ephemeris data, common TA i parameters, k_ offset, validity duration for UL sync information and epoch. i nin-NeighCellConfigLisi, nin-NeighCeiiConfigListExt i Provides a list of NTN neighbour cells including their ntn-Config, carrier frequency and PhysCellld. This set i includes all elements of ntn-NeighCellConfigList and all elements of ntn-NeighCellConfigListExt. If ntn-Config i is absent for an entry in ntn-NeighCellConfigListExt, the ntn-Config provided in the entry at the same position i in ntn-NeighCellConfigList applies. i referenceLocation i Reference location of the serving cell provided via NTN quasi-Earth fixed system and is used in location- i based measurement initiation in RRC IDLE and RRC INACTIVE, as defined in TS 38.304

[20] , i t-Service i Indicates the time information on when a cell provided via NTN quasi-Earth fixed system is going to stop i serving the area it is currently covering. The field indicates a time in multiples of 10 ms after 00:00:00 on i Gregorian calendar date 1 January, 1900 (midnight between Sunday, December 31,1899 and Monday, i January 1, 1900). The exact stop time is between the time indicated by the value of this field minus 1 and the i time indicated by the value of this field. ------------------------------3GPP TS 38.331 V17.2.0------------------------------ In loT NTN, SIB31 contains the required information to access an loT NTN cell: ------------------------------3GPPTS 36.331 V17.2.0------------------------------ SystemlnformationBlockType31 The IE SystemlnformationBlockTypeSl contains satellite assistance information for the serving cell. SystemlnformationBlockTypeSl is only signalled in a NTN cell. SystemlnformationBlockTypeSl information element -- AclIlRTART Syatehilnft'niiatit'nElt'eJ'.Tyiae.ll-rli : := 3EQVE1ICE ( aervingSatelliteInfc’-rl = GervingSatellitelnfa-rl" , lateNi'nCritiealEntenaian OCTET STRING OPTIONAL, Ser=ingSatelllteInfo-rl" ::= e pit e me r 1 a I a f a - r 11 atate.Ectura a rbi t a1P a r ame t e r a iiiliiliiiiiiiiiiiiiiiiilii nt a-'li'nimi'n-rll nt a-CommonDni ft-ml" :gEyyy|:||||||||||||||||||||||||| EptiemeriaStateVectare-rl" , EphemeriaOrbit al Par aiiiet era~rl= INTEGER (1-..1.11611=) INTEGER t-m:lrO = . . m:lrO = > nta-OammenDrift"ariatian-vli INTEGER (6. .1941?) ul-Synei'aliditiTjuratian-rl - EllinIERATEP- (al, al1?, all, al?1, OPTIONAL, OPTIONAL liiiiiiiidi a 11 'J, all 'J , -- Meed OP -- Need OP' Need Op Idiiiilllil ^-4 = , ^l1111), 10 to t S u b F it ..¾ m e - r 17 .....................J................................. ::: ....................................................... — Amim >p 1025), lllii 15 ; SystemlnformationBlockType31 field descriptions i epochtime ] ; Epoch time of the satellite ephemeris data and common TA parameters, see TS 36.213

[23] , The reference I I point for epoch time of the serving satellite ephemeris and Common TA parameters is the uplink time i i synchronization reference point. I i epochTime is the starting time of a DL subframe indicated by startSFN and startSubframe. | i If the field is absent, the UE uses the starting time of the DL subframe corresponding to the end of the SI i ; window during which the SI message carrying SIB31 is transmitted. I I E-UTRAN always includes epochTime when SystemlnformationBlockType31 is provided through dedicated i i signalling. I I k-Mac i Scheduling offset used when downlink and uplink frame timing are not aligned at the eNB, see TS 36.213 I i

[23] , Unit in ms. i i If the field if absent, the UE uses the (default) value of 0. i i k Offset i Scheduling offset used in the timing relationships in NTN, see TS 36.213

[23] , Unit in ms. i i nta-Common i Network-controlled common TA, see TS 36.213

[23] , Unit of ps. i i Step of 32.55208 *1 O'3 ps. Actual value = field value * 32.55208 *1 O'3 LlfJthejnejcM^absentj the UE i i nta-CommonDrift i Drift rate of the common TA, see TS 36.213

[23] , Unit of ps / s. i i Step of 0.2 *1 O'3 ps / s. Actual value = field value * 0.2 *1 O'3 I i If the field is absent, the UE uses the (default) value of 0. i i nta-CommonDriftVariation i Drift rate variation of the common TA, see TS 36.213

[23] , Unit of ps / s2. i i Step of 0.2 *1 O'4 ps / s2 Actual value = field value * 0.2 *1 O'4 I i If the field is absent, the UE uses the (default) value of 0. I i orbitalParameters i Instantaneous values of the satellite orbital parameters. The signalled values are only valid for the duration I (as defined by uJ-SyncVa / idat^i i stateVectors i Instantaneous values of the satellite state vectors. The signalled values are only valid for the duration as i ( defined by~~^ I i ul-SyncValidationDuration ; Validity duration of the satellite ephemeris data and common TA parameters, i.e. maximum time during I i which the UE can apply the satellite ephemeris without acquiring new satellite ephemeris, see TS 36.213 | i

[23] , Unit in second. i ; Value s5 corresponds to 5 seconds, value si0 corresponds to 10 seconds and so on. I ------------------------------3GPPTS 36.331 V17.2.0------------------------------ The system information contains the following: - Serving cell ephemeris elements. This allows the UE to calculate the satellite position for doppler and time pre-compensation. This information may be provided in two formats: o PVT format. This describes a (X,Y,Z) position as well as a speed vector (vX, vY, vZ). o Orbital parameters. This describes the orbital movements of the satellite which is then used to infer the satellite position. - TA common parameters. This provides the common timing advance parameters which is introduced to compensate for the feeder link delays. The signalling comprises the following (in total taking up 57 bits): o Absolute TA common (23 bits). o Drift of the TA common, defining how the TA common drifts, i.e. the first derivative of the TA common (19 bits). o Variation of the TA common, defining how the TA common varies, i.e. the second derivative of the TA common (15 bits). - Synchronization validity duration. This is used to define how long the ephemeris and TA common is valid. Epoch time. This defines when the synchronization validity duration should start. K-Offset. This is a scheduling offset for timing relationship in NTN. K-Mac. This is a scheduling offset used when the downlink and uplink frame timing is not aligned. NR NTN specific information also includes (as part of 3GPP TS 38.331): o T-Service (signalled in SIB3 in loT NTN). o Reference location and distance threshold. This is used for location-based measurement initiation in RRC IDLE and RRC Connected mode. o Neighbour cell ephemeris. This is used for idle mode measurements. Overview of NTN System Information Acquisition As ephemeris information constantly changes due to the movement of the NTN payload (e.g. satellite), there is a need to make sure that the UE is correctly synchronized. Thus, whenever a UE connects to an eNB, the UE needs to read the system information (e.g. SIB19 or SIB31). In loT NTN, every time SIB31 is read, a timer (T317) associated with the ephemeris element is started. At expiry of T317, the UE is no longer considered synchronized and should reacquire SIB31 in order to stay synchronized. In loT NTN, since an loT UE (LTE-M and NB-loT UE) is not expected to be able to acquire system information in connected mode, the UE tunes away and is likely unreachable while reading SIB31. If the loT NTN UE is unable to read the SIB31 within a timer (T318) with a configured duration, the UE performs Radio Link Failure (RLF) similar to other cases where RLF is performed. This operation can be seen in Figure 1. In NR NTN, the UE shall ensure that it has a recent ephemeris (SIB19 in NR) by reading the SIB in time by UE implementation. Overview of NTN Ephemeris Formats There are three ways of signalling the ephemeris in NTN: 5 1. PVT format, 2. Orbital ephemeris elements, and 3. TLE ephemeris elements (only used for Discontinuous Coverage in loT NTN). PVT Format PVT format signals XYZ position along with the speed vector vXYZ. This can be seen in the 10 following information element: ------------------------------3GPPTS 36.331 V17.2.0------------------------------ - EphemerisStateVectors The IE EphemerisStateVectors provides satellite ephemeris in format of position and velocity state vectors in ECEF. 15 EphemerisStateVectors information element 30 jOsOMIlissSsSsSjsSsSsSsSsSsSsSsSsSsSsSsSsSjs EphemerisStateVectors field descriptions i positionX, posiiionY, positionZ : X, Y, Z coordinate of satellite position state vector in ECEF. Unit in meter. ; Step of 1.3 m. Actual value = field value *1.3. i velociiyVX, velocityVY, veiocityVZ ; X, Y, Z coordinate of satellite velocity state vector in ECEF. Unit in meter / second. I Step of 0.06 m / s. Actual value = field value * 0.06. ------------------------------3GPPTS 36.331 V17.2.0------------------------------ The position elements (X, Y, Z respectively) each occupy 26 bits and the speed elements (vX, 35 vY, vZ) each occupy 18 bits. Altogether they occupy 132 bits. Orbital Ephemeris Format The ephemeris orbital parameters (also referred to as Keplerian format) provide parameters that indicate how a celestial body moves in space, which allows for accurate synchronization and prediction of future NTN payload position. Ephemeris orbital elements are signalled by the following elements (164 bits total): SemiMajorAxis (33 bits) Eccentricity (20 bits) Periapsis (28 bits) Longitude (28 bits) Inclination (27 bits) - Anomaly (28 bits) TLE Orbital Parameters The TLE parameters are based on Two-Line Element set (TLE), which is industry-acknowledged data format for signalling the movement of a celestial body. Whereas the PVT and orbital ephemeris formats may be used to perform accurate synchronization, TLE parameters may be used primarily for long term prediction. For example, the TLE parameters allow for accurate satellite-pass prediction of up to several days in the future. A full set of TLE parameters can occupy more than 50 Bytes of data containing many fields not required in 3GPP. Therefore, a reduced set of TLE parameters may be used instead, for example based on the following (totalling 189 bits): Inclination (21 bits) - Argument of perigee (22 bits) Right ascension of the ascending node (22 bits) Mean anomaly (22 bits) Eccentricity (24 bits) Mean Motion (34 bits) B* signalled by (i) a decimal (18 bits), and (ii) an exponent (5 bits) Epoch star (21 bits) 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. 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. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1a and 1b illustrate examples of an ephemeris synchronization operation: in Figure 1a SIB31 functions as normal, and in Figure 1b UE fails to read SIB31 during T318 which then expires and triggers RLF; Figure 2 illustrates an example of a neighbour cell request and response through dedicated signalling initiated by UE; Figure 3 illustrates an example of a neighbour cell ephemeris request provided in a UE assistance information message; Figure 4 illustrates an example of moving to RRC connected mode from RRC idle mode to acquire neighbour cell ephemeris information; Figure 5 illustrates an example of reading SIB containing neighbour cell ephemeris after reading SIB31 after uplink synchronization has expired (T317) with an extended guard timer (T318); Figure 6 illustrates an example of providing NTN neighbour cell ephemeris over a TN cell; Figure 7a illustrates an example of acquiring broadcast NTN neighbour cell ephemeris, and Figure 7b illustrates an example of indicating that NTN cell ephemeris is needed through dedicated signalling; and Figure 8 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, functions, operations 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 are to be understood to be applicable to any other aspect, embodiment, example or claim described herein unless incompatible therewith. The skilled person will appreciate that the techniques described herein may be used in any suitable combination. Certain examples of the present disclosure provide one or more techniques for providing neighbour cell information in a NTN. For example, certain examples of the present disclosure provide one or more techniques for providing neighbour cell information in a 3GPP 5G NR NTN. 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, including any existing or future releases of the same standards specification, for example 3GPP5G. The functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in the same or any other suitable 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 or purpose within the network. For example, the functionality of a NG-RAN node (e.g. a base station or gNB) in the examples below may be applied to any other suitable type of entity performing RAN functions. 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 (e.g. network or wireless communication system) comprising one or more such apparatuses / devices / network entities, and / or a method therefor. Neighbour cell ephemeris signalling In loT NTN, 3GPP RAN2#120 meeting the following was agreed: Agreements: 1. RAN2 doesn’t introduce neighbour cell ephemeris in Rel-17 loT-NTN, neither for eMTC not for NB-loT. RAN2 agrees to support this in Rel-18, with details FFS. In LTE loT, as opposed to NR, the smallest maximum Transport Block Size (TBS) is 1000 and 680 bits for a Release 13 LTE-M and NB-loT respectively and with appropriate headers (for example MAC, RLC, PDCP and RRC headers) the RRC payload is even less. However, a single ephemeris element may require more than 120 bits, up to more than 200 bits depending on network implementation and deployment. Therefore, there may be a limitation on the number of blocks of neighbour cell ephemeris information that may be signalled. Since loT devices are typically less capable devices in terms of radio sensitivity, the number of receive antennas and worse processing capabilities, introducing significantly more bits in System information may worsen the network performance. Access and mobility in a NTN relies on ephemeris and NTN configurations. For idle mode it is used to adjust the SSB-Measurement Timing Configuration (SMTC) and also to enable NTN-specific idle mode cell selection and reselection. In NTN, these configurations are broadcast in SIB19 (NR NTN) / SIB31 (loT NTN). If the UE is in idle mode and camps on an NTN and needs to measure a neighbouring cell that is a non-terrestrial cell, then it is not clear how the UE would acquire the needed information elements since SIB31 are NTN-specific. Certain examples of the present disclosure provide various techniques for providing neighbour cell ephemeris information that mitigate these problems. The skilled person will appreciate that the various techniques disclosed herein are not only applicable to ephemeris information, but to any other suitable type of information. The skilled person will appreciate that the various techniques disclosed herein are not only applicable to satellite payloads, but can also apply to other platforms, for example HAPS. Accordingly, references to “satellite ephemeris” may include references not only to satellites but also other NTN platforms or payloads. The skilled person will appreciate that the various techniques disclosed herein are not only applicable to “serving” cells and “neighbouring” cells but to any other suitable types of cells, which may be referred to as “first” and “second” cells, respectively. The skilled person will appreciate that the various techniques disclosed herein may be applied to gNB, NG-RAN cases and all related RRC signalling and / or messages, and to X2, Xn, S1, NG, F1 signalling and messages, and / or related network entities (e.g. MME, AMF, other). The skilled person will appreciate that the various techniques disclosed herein may be applied to loT NTN and / or NR NTN. Various exemplary techniques for signalling neighbour cell ephemeris information will now be described. In certain examples, the network may signal the neighbouring cell ephemeris with lower accuracy (e.g. precision, granularity, and / or coarse values, for example in terms of size / content of information elements represented in bits) as compared to serving cell ephemeris. Signalling of neighbour cell ephemeris at lower granularity / precision may be acceptable, considering that this information may not be used to synchronize with the cell, but rather for cell measurements which would typically require lower cell information precision. In certain examples, the precision may be configurable, for example by having multiple information elements representing the ephemeris that are then selected by the network according to the purpose. For example, the precision may depend on the NTN deployment, where in the case of satellites that move relatively slowly, there is less need to have precision related to the speed of the satellite. An example of this signalling case is disclosed in Example 1 further below. In certain examples, the precision (e.g. lower precision) may be configured by one or more specific parameters. For example, the precision parameter(s) may signal the number of bits for each parameter, or a reduction in the number of bits used to signal the parameters compared to existing ephemeris parameters. In certain examples, certain neighbour cell ephemeris information (e.g. not all) may be provided at reduced information precision / resolution / granularity. In this case, certain other neighbour cell ephemeris information may be provided with full precision / resolution / granularity. In certain examples, the network may require the neighbour cell ephemeris to be provided in a certain form (e.g. single more efficient type). For example, the network may require that the neighbouring cell ephemeris is signalled using the PVT ephemeris format, which uses a relatively low number of bits, or any other suitable relatively low precision format. In certain examples, the Common TA, which may be considered a part of ephemeris, may have its precision lowered in neighbour cell ephemeris. This may be done independently or jointly with lowering of precision of other neighbouring cell ephemeris information (e.g. signalling of the satellite position). In various examples, the precision of neighbour cell ephemeris (e.g. PVT, keplerian format, etc.) may be lowered while the precision of Common TA is not lowered, or the precision of both Common TA and ephemeris may be lowered. In certain examples, the neighbour cell ephemeris may be only partly signalled in each System Information occasion. For example, if the neighbour cell ephemeris is signalled in SIB31, the neighbour cell ephemeris may be signalled only in certain SIB31 occasions. In certain examples, the network may provide the content (or parts) of neighbour cell information using more than one SIBs, for example in existing and / or newly defined SIBs. For example, the content of neighbour cell ephemeris may be split into different SIBs (existing and / or newly defined). The network may indicate to the UE(s) where to find the different content of neighbour cell ephemeris, i.e. in which SIBs. In certain examples, the network may indicate which content (or parts) of neighbour cell information is provided to the UE(s), for example through system information broadcast (e.g. periodically or on-demand) and / or dedicated signalling. In certain examples, the network may provide to the UE(s) information on the availability and / or scheduling of neighbour cell ephemeris. For example, the information may be provided through system information or dedicated signalling. For example, the information may include information on a mapping of neighbour cell ephemeris to new and / or existing SIBs. For example, the information may include information on periodicity, broadcast type (e.g. on-demand, periodical), size, resolution / precision / granularity of the neighbour cell ephemeris. In certain examples, all of the neighbour cell ephemeris, or only a part of the neighbour cell ephemeris (e.g. a part provided / represented at lower precision or granularity), may be provided to the UE(s) via broadcast on-demand following a request from the UE(s), for example UEs in RRCJDLE, RRC_INACTIVE, or RRC_CONNECTED. In certain examples, all or a part of the neighbour cell ephemeris may be provided to the UE(s) following an on-demand request, for example through a system information broadcast (periodically, on-demand) and / or dedicated signalling. In certain examples, the neighbour cell ephemeris may be provided through dedicated signalling only, without being broadcast. This may be advantageous in some situations as neighbour cell ephemeris may not be needed if the UE is only connected for a very limited amount of time and neighbour cell ephemeris risks causing problems with broadcast coverage. In this case, the UE may signal, once it has connected, that it requires neighbour cell ephemeris. For example, the UE may signal this in response to the UE having a relatively large amount of data in a buffer. An example of this signalling is illustrated in Figure 2. In certain examples, the UE may determine whether NTN neighbour cell ephemeris is needed, whether the ephemeris is required at full information precision or reduced precision, and / or whether full ephemeris or only part of the ephemeris is needed, based on any suitable set of one or more criteria, for example including one or more of the following: - The volume of data in a buffer is above a given / predefined threshold. For example, this may mean that the UE will remain in connected mode for long enough where the neighbour cell measurements will be required. - The serving cell signal strength is below a given / predefined threshold. For example, this may mean that mobility may be needed soon, thus the information to perform mobility may be required. - The neighbour cell(s) are being served by a different satellite. For example, this may indicate that the serving cell ephemeris are different to the neighbour cell ephemeris, in which case it may not be possible to derive / infer the neighbour cell ephemeris from serving cell ephemeris. In certain examples, the indication of NTN neighbour cell ephemeris may be included in any suitable message, for example one or more of the following: In any RRC - Complete message (sometimes referred to as Msg5): o RRCConnectionSetupComplete o RRCConnectionResumeComplete o RRCConnectionReconfigurationComplete o RRCConnectionReestablishmentComplete o The network may indicate that the above should be provided / indicated. This may be needed if for instance there are some eNBs that have not implemented methods to send neighbour cell measurements, and some eNBs have, in which case there may be no need to send the above indication in some cases. For example, an indication that the above should be indicated may be sent in a broadcast fashion, such as SIB1 or SIB2. In a UE assistance information message o The RRC message is UEAssistancelnformation (see Figure 2) Measurement Report o Whenever a measurement report is triggered due to RRC measurements, the UE may indicate, for example in a flag, that neighbour cell ephemeris is needed. o The RRC message is MeasurementReport o This may be configured in a reporting configuration (e.g. ReportConfigEUTRA) through a flag indicating that the need for neighbour cell ephemeris should be indicated in a Measurement report. - In a MAC CE In certain examples, the request and the response of neighbour cell ephemeris may be done in a new RRC message, for example Neighbour Cell Ephemeris Request / Response messages, or in one or more newly defined lEs, for example NeighbourCellEphemerisRequest / NeighbourCellEphemerisResponse. In certain examples, the UE may provide, in the request for the neighbour cell ephemeris, an indication of required / desired information, for example an indication of which part of the neighbour cell ephemeris is required, or the expected / required granularity, etc. In certain examples, if the only method used to deliver / acquire neighbour cell ephemeris is through dedicated signalling, the UE may move from RRC idle mode to RRC connected mode to acquire neighbour cell information if the UE requires neighbour cell ephemeris for RRC idle mode operation. In certain examples, the UE may indicate the cause for connecting to the eNB, specifically to acquire NTN neighbour cell ephemeris (e.g. establishmentcause, resumeCause, re-establishmentCause). An example of this procedure is illustrated in Figure 4. In certain examples, if the neighbour cell ephemeris is broadcast, then in order to read the broadcast information, the UE may transition from RRC_CONNESTED or RRC_IDLE. This may for instance be done by the UE signalling that it wants to go to RRC_IDLE due to needing to acquire neighbour cell ephemeris. For example, this may be done using Access Stratum Release Assistance Indication (AS RAI), or by using ReleasePreference and further indicating that the AS RAI or ReleasePreference is due to the need of reading neighbour cell ephemeris. In certain examples, if the neighbour cell ephemeris is the same as the serving cell ephemeris, the network may signal this situation, for example using a flag. This may avoid the need to signal neighbour cell ephemeris in this case. In certain examples, for each neighbouring cell, the network may only signal certain information, for example the needed PCI, the frequency, etc. This may allow for backwards-compatible implementation. See Example 2 further below. In certain examples, if the NTN network wants the UE to monitor a neighbouring TN cell, the network may signal that it is a TN cell. This may for instance be implicit by not including the ephemeris element, or explicit through a flag. In certain examples, the UE may indicate its capabilities to read neighbour cell ephemeris. This can for instance be that UE is capable of reading a specific type of format that has lower resolution / precision / granularity. Newly defined SIB for neighbour cell ephemeris In certain examples, the neighbour cell ephemeris may be provided in a newly defined SIB. In this case, there may be requirements on when the new SIB is to be read, along with requirements and actions of reading the current NTN system information, such as SIB31. In certain examples, the UE may be configured to be required to read the new neighbour cell ephemeris SIB according to one or more of the following: - Whenever the capable NTN UE reads SIB31, or just directly after having read SIB31. This may provide an advantage that the actions when reading SIB31 can be duplicated. This also requires the network to broadcast the new neighbour cell ephemeris SIB directly after the SIB31. An example of this is disclosed in Example 3 further below. o To deal with the problem of extended time for reading system information, a longer time T318 may be configured for this specific case. An example of this is illustrated in Figure 5. o The reading of the new neighbour cell ephemeris SIB may not require its own T317 (uplink sync - ul-SyncValidityTimer) timer. ■ In certain examples, the UE may acquire the new neighbour cell ephemeris SIB whenever the SIB31 is acquired if it is detected that there have been changes to the new SIB. In some cases, when the NTN UE reads the SIB31, such as: o When reading SIB31 when going for idle mode to connected mode. o When re-establishing connection to an NTN cell. - When certain conditions are fulfilled: o UE has more data than a certain amount in the buffer. o UE is capable of monitoring neighbouring cells in RRC connected mode. In certain examples, the UE may be capable of monitoring neighbouring cells in RRC idle mode using NTN neighbour cell assistance information. In certain examples, the UE may be allowed to request new SIB(s) on-demand. NTN neighbour cell information signalled in Terrestrial Network In NR NTN and loT NTN, idle and connected mode mobility is supported between a terrestrial network and a non-terrestrial network. In certain examples, the network may signal the required non-terrestrial information in a terrestrial network. This allows the UE to measure on a non-terrestrial network while being on a terrestrial network. In certain examples, to signal the above the network may broadcast the NTN SIB (e.g. SIB19 for NR NTN and SIB31 for loT NTN) in a terrestrial network. To indicate that the terrestrial network is not an NTN, a flag may be included in the system information. In certain examples, the NTN neighbour cell information may be delivered to UEs in a dedicated manner. For example, this may be done through dedicated System Information delivery of SIB19 or SIB31, or in any other suitable manner, such as a separate information element with neighbour cell information, which can be sent in a separate message or as part of RRC configuration. For (i) acquiring the NTN system information in a terrestrial network that is broadcast, or (ii) if provided through dedicated signalling, the UE may be configured to (a) be required to acquire the NTN system information in SIB19 or SIB31 (see Figure 7a), or (b) indicate that the UE needs dedicated NTN neighbour cell ephemeris (see Figure 7b). In certain examples, the conditions for any of the above may be one or more of the following: - The UE is NTN-capable. - The network indicates that it is required, for instance by configuring a flag. - The coverage of the UE is poor. - There is a radio link failure. If the related SIB is present in a terrestrial network. In certain examples, whether to acquire the NTN system information may be determined according to UE implementation and / or use, for example one or more of the following: If the UE is expected to operate in an environment where mobility to NTN is required. Using past history of connecting to NTN. The serving cell ephemeris is usually present in an NTN (it is optionally present in SIB19 and mandatory present in SIB31). Certain examples of the present disclosure address this problem: - The network does not signal serving cell ephemeris when the NTN SIB is signalled in a terrestrial network. This may be done for NR NTN as the serving cell ephemeris in SIB19 is optionally present. - The serving cell ephemeris is ignored. This may be done for loT NTN as the serving cell ephemeris is mandatory present. It may for instance be ignored based on the configuration of a flag indicating to the UE that it should be ignored. In certain examples, the ephemeris signalled value may indicate this implicitly. As an example, the PVT ephemeris values may be (x=0, y=0, z=0, vx=0, vy=0, vz=0). o In this case, certain serving cell ephemeris fields may be defaulted to not be signalled, such as TA common parameters, epoch time, k-Mac, etc. - The serving cell ephemeris may be repurposed to indicate a neighbouring NTN cell ephemeris if it is signalled in a terrestrial network. In certain examples, the UE may indicates its capability to acquire NTN neighbour cell ephemeris to either a terrestrial network or a non-terrestrial network, or both. Examples Example 1 ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- System lnformationBlockType31 The IE SystemlnformationBlockType31 contains satellite assistance information for the serving cell. SystemlnformationBlockType 31 is only signalled in a NTN cell. SystemlnformationBlockType31 information element — A.3N13TA.RT G'j'otouiIiitO'riiiatiO'nE.lookTbpo 51-rlT ::= GEONENCE [ oerringGatellitelnfo-rll 3 = r-.-irig3.atelliteInfo-rl", IlteNonClltloalEGte-naion OCTET 5TRING OPTIONAL, ... spec text omitted ... - EphemerisOrbitalParameters The IE EphemerisOrbitalParameters provides satellite ephemeris in format of orbital parameters in ECI. EphemerisOrbitalParameters information element — AGN1GTART) Eplieuierio Orbit Parameters -rl^ a emil I a j o, r a; : 1 a ~ r 1 t eo:entri:it;-rl^ INTEGER ¢0- .6569554551), INTEGER ¢0. .1614.15455) , INTEGER ¢6..166455455), INTEGER (6..165455455) EphemerisOrbitalParameters field descriptions i anomaly i Mean anomaly M at epoch time, see NIMA TR 8350.2

[110] , Unit in radian. | Step of 2.341* 10-8 rad in EphemensOrtxfa / Parem^^ Step of 2 x 2.341* 10 s rad in i EphemerisOn&ffa / Paramete.r$Reduced<f 8. Actual value = field value * (2.341* 10-8). i eccentricity ; Eccentricity e, see NIMA TR 8350.2

[110] , i Step 1.431 * 10-8 in EphemehsOr&'ta / Parameters-rfZand Step of2x 1 431 * 10 s in i Epheme / 7sO?6ita / Param^ersReduc®d-r?8. Actual value = field value * (1.431 * 10-8).___________ i inclination i Inclination i, see NIMATR 8350.2

[110] , Unit in radian. i Step of 2.341* 10-8 rad in EptemarfsOntHfa^^ 7 and Step of 2 x 2.341* W3 rad in i EphemensOmifa / Paramefers^^ Actual value = field value * (2.341* 10-8). i longitude i Longitude of ascending node Q, see NIMA TR 8350.2

[110] , Unit in radian. i Step of 2.341* 10-8 rad in EphemensOrfc / ta / Parameters-rl 7 and Step of2x 2.341* 1O rad in i Epheme / 7sO?6ita / Param^ersRedac®d-r?8. Actual value = field value * (2.341* 1Q-8).____________ i periapsis i Argument of periapsis co, see NIMA TR 8350.2

[110] , Unit in radian. | Step of 2.341* 10-8 rad in EphemensOrtxfa / Par^ Step of 2 x 2.341* 10 s rad in i EphemeffsOn&tfa / ParametersRedaced-rf 8. Actual value = field value * (2.341* 1Q-8).____________ i semiMajorAxis i Semi major axis a, see NIMA TR 8350.2

[110] , Unit in meter. | Step of 4.249* 10-3 m in EphemensOrMa / Param©fers-r17 and step of 2 x 4.249 * 10 s m in I Eph®mehsOri!> / fa / ParametersReduced-r18. Actual value = 6500000 + field value * (4.249 * 1Q-3), - EphemerisStateVectors The IE EphemerisStateVectors provides satellite ephemeris in format of position and velocity state vectors in ECEF. EphemerisStateVectors information element — ASlIlcTART ptaitionZ-rl'E pyaitiyn-i-rlt pyaitiyriE-i:!" "elicityVP-rli --eLacity'V-rV yely'EityVS~rl? pyaitiynEt atb'aytyr-rl^ Pyatt ionSt atpr'act y r-rl" PC'S it iyriEtatR'ectyr-rl" Vt 1 y y i t y S t a 13 'a y t y r ~ r 1 ' re 1 y y11 y31 a t =V= y t y r - r 1" ValyyitySt ata'-yytyr-rli pyaitiynRtateVyatyr-rlt ::= ItITEGER ( -E35544 E2 . , E35544 E1) -- AElIlGTop EphemerisStateVectors field descriptions positionX, posiiionY, positionZ X, Y, Z coordinate of satellite position state vector in ECEF. Unit in meter. Step of 1.3 m for EphemerisStateVectors-r17 and step of 2.6 m for EphemerisStateVectorsReduced-r18. Actual value = field value *1.3 or field value * 2.6. veiocityVX, velocityVY, velocityVZ X, Y, Z coordinate of satellite velocity state vector in ECEF. Unit in meter / second. Step of 0.06 m / s for EphemerisStateVectors-r17 and step of 0.12 m / s for EphernerisStaieVeciorsReduce r18. Actual value = field value * 0.06 or Meld value 0.12 m / s. ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- Example 2 In this example, the network signals that the neighbouring cell ephemeris is the same as the serving cell ephemeris. System lnformationBlockType31 The IE SystemlnformationBlockType31 contains satellite assistance information for the serving cell. SystemInformationBlockType31 is only signalled in a NTN cell. SystemlnformationBlockType31 information element -- AGIUPTART GyitemlnformationE'.loakTypeSl-rll : := 3EQUEHCE ( a er—ingE atelliteInfe--rlT E-ac-ingl at 111111 Inf o-i’l" 1 ateWonCriticalEztmsic-n OCTET 3TRIHG P-i'rinaGatellit-Inf e-rl. :: = eyhemerialnf o-rl^ atatARctari orbit alParauietera nt a-Ciminori-rl^ OPTIOIIAL, OOlliliilililililililili 011111111111111111111111111111111111111111111111111111111111111111111 EpTiTimriaEtatatArtora-rl" , Eplieaue-i’ia Orbit alPai’aiua-t era -ri" 111111111111110 I1ITEGER ( / ..AlcAA OPTIOIIAL, AsiiOOiHil nt a-CiihimanPrift-rir liilllllllllOli ul-Ryn’A'alidit yDurat irn-rin 1 / 1 / 1 / 10011111111111111111111111111111111111111111 atartEubFrame-rli illiIlOOfl111111111111111111111111111s 111111111111111111111111111111111111111 1111111111111111110111110 17 I1ITEGER pj. . i 94" 9 ) EtlUMERATED (a5, air, al5, 11111111111111 11111111111111110111111111111110 iiiiiiiiiiiiiiiliM iiiiiiiiBiBlililil 11111100011111111111111111111111 5) OPTIOIIAL, -- IKed OP 111111111111101001 / 1111111101111111111111 / IP, s25, sir, a .3 5, sir, ai’ti, alI9, alS9, 1149, 1999} , l11111iBllOl|111l OPTIOIIAL, — Reed OP 10 SystemlnformationBlockType31 field descriptions epochTime Epoch time of the satellite ephemeris data and common TA parameters, see TS 36.213

[23] , The reference I point for epoch time of the serving satellite ephemeris and Common TA parameters is the uplink time I synchronization reference point. i epochTime is the starting time of a DL subframe indicated by startSFN and startSubframe. I If the field is absent, the UE uses the starting time of the DL subframe corresponding to the end of the SI i window during which the SI message carrying SIB31 is transmitted. I E-UTRAN always includes epochTime when SystemlnformationBlockType31 is provided through dedicated I signalling. i k-Mac Scheduling offset used when downlink and uplink frame timing are not aligned at the eNB, see TS 36.213 i

[23] , Unit in ms. I If the field if absent, the UE uses the (default) value of 0. [ k-Offsei Scheduling offset used in the timing relationships in NTN, see TS 36.213 [23} Unit in ms. [ nta-Common Network-controlled common TA, see TS 36.213

[23] , Unit of ps. [ Step of 32.55208 xio 3ps. Actual value = field value * 32.55208 xw3. i If the field is absent, the UE uses the (default) value of 0. I nta-CommonDrift Drift rate of the common TA, see TS 36.213

[23] , Unit of ps / s. i Step of 0.2 xiO’3 ps / s. Actual value = field value * 0.2 x10'3. i IHhe field is absent, the I nta-CommonDriftVariation Drift rate variation of the common TA, see TS 36.213

[23] , Unit of ps / s2. I Step of 0.2 xio-4 ps / s2. Actual value = field value * 0.2 x10'4. i If the field is absent, the UE uses the (default) value of 0. I orbitalParameters Instantaneous values of the satellite orbital parameters. The signalled values are only valid for the duration I as defined by ul-SyncValidationDuration and epochTime. [ stateVectors Instantaneous values of the satellite state vectors. The signalled values are only valid for the duration as defined by ul-SyncValidationDuration and epochTime. ul-SyncVaiidationDuraiion Validity duration of the satellite ephemeris data and common TA parameters, i.e. maximum time during which the UE can apply the satellite ephemeris without acquiring new satellite ephemeris, see TS 36.213

[23] , Unit in second. Value s5 corresponds to 5 seconds, value si0 corresponds to 10 seconds and so on. Example 3 In this case, the UE acquires the neighbour cell ephemeris in RRC idle mode if it is capable of 15 performing NTN neighbour cell measurements using the NTN ephemeris and if it is capable of performing NTN neighbour cell measurements in RRC connected mode using the NTN neighbour cell ephemeris. The UE also reads the new SIB directly after SBI31. ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- 5.2.2.3 System information required by the UE The UE shall: 1> ensure having a valid version, as defined below, of (at least) the following system information, also referred to as the 'required' system information: 2> if inRRCIDLE: 3> if the UE is a NB-IoT UE: 4> the MasterlnformationBlock-NB / MasterlnformationBlock-TDD-NB and SystemlnformationBlockTypel-NB as well as SystemlnformationBlockType2-NB through SystemlnformationBlockType5-NB, SystemInformationBlockType22-NB', 3> else: 4> the MasterlnformationBlock and SystemlnformationBlockTypel (or SystemlnformationBlockTypel-BR depending on whether the UE is a BL UE or the UE in CE) as well as SystemlnformationBlockType2 through SystemlnformationBlockType8 and SystemInformationBlockType24 (depending on support of the concerned RATs), SystemlnformationBlockTypel? (depending on support of RAN-assisted WLAN interworking when the UE is connected to EPC), SystemInformationBlockType25 (depending on support of E-UTRA / 5GC), SystemInformationBlockType29 (only for BL UE or the UE in CE depending on support of resource reservation), SystemInformationBlockType21, SystemInformationBlockType26 (if UE is capable of V2X sidelink communication and is configured by upper layers to receive or transmit V2X sidelink communication), and SystemInformationBlockType28 (if UE is capable of NR sidelink communication and is configured by upper layers to receive or transmit NR sidelink communication), SystemInformationBlockType30 (if UE is configured by upper layers to report disaster roaming related information), and SystemlnformcrtiorLBlockT^^ (if UE is capable of performing 3> if initiating a RRC connection establishment / resume procedure; and 3> the UE is NTN capable: 4> SystemlnformationBlockTypeS 1 (SystemlnformationBlockTypeS 1 -NB inNB-IoT), if scheduled; 4> SystemlnformationBlockTypeXX (if UE is supports performing measurements using NTN ... spec text omitted ... 5.2.2.4 System information acquisition by the UE The UE shall: ... spec text omitted ... 1> if the UE is NTN capable: 2> if schedulinglnfoList indicates that SystemlnformationBlockTypeS 1 (SystemlnformationBlockTypeS 1 -NB in NB-IoT) is present: 3> immediately before establishing, resuming or re-establishing an RRC connection; or 3 >if in RRC CONNECTED and T317 is not running: 4> acquire SystemInformationBlockType31 (SystemInformationBlockType31-NB inNB-IoT); 2> if the UE supports discontinuous coverage; and 2> if schedulinglnfoList indicates that SystemInformationBlockType32 (SystemInformationBlockType32-NB in NB-IoT) is present and the UE does not have a valid version of this system information block: 3> acquire SystemInformationBlockType32 (SystemInformationBlockType32-NB inNB-IoT); ... spec text omitted ... 5.3.18 T317 expiry The UE shall: 1> if in RRC_CONNECTED: 2> inform lower layers that the UL synchronisation is lost; 2> start timer T318; 2> acquire SystemInformationBlockType31 (SystemInformationBlockType31-NB inNB-IoT) as specified in 5.2.2; and, 2> upon successful acquisition of SystemInformationBlockType31 (SystemInformationBlockType31-NB inNB-IoT); and 3> stop timer T318; 3> inform lower layers that the UL synchronisation is restored; NOTE: SystemInformationBlockType31 (SystemInformationBlockType31 -NB inNB-IoT) may be broadcast on a different narrowband or different NB-IoT carrier than the one configured to the UE. ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- Example 4 In this example, the T318 timer is extended for the UEs that are attempting to acquire the new SIB containing neighbour cell ephemeris. ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- - RadioResourceConfigCommon The IE RadioResourceConfigCommonSIB and IE RadioResourceConfigCommon are used to specify common radio resource configurations in the system information and in the mobility control information, respectively, e.g., the random access parameters and the static physical layer parameters. A0H1START RadioResourceConfigCommon information element RadigRe EDT OR aaaaaaaaaaaaaaaassa AbRAAsAbffiHdBsssssssss -Cunfig prauh-Cunfig pdalh-CinfigCimmin AdRAAAAObAigQgAmdAgggggggggg: puguh-CunfigCummin a : undiiigRS-UL-C: nf i pi: mum n uplinhPi' ArOint rd Ccmmon SEQUEHCE ( R A.c H-Cu n f i gCummu n, EACH-Ccnfig, POCH-Cmf ig, PRA.CH-Cinf igSIE , PDSCH~CmfigCcmmon, E'USCH-Cinf igCimmin, PUCCH-cinfigCimmin, Su-undingRS-UL-Cu-nf igCumm ?????? Ala ABOOSggigggagoSa UL-CyclisPrsfizLsngth, [ [ ] 1 [ [ ] ] [ [ ] ] [ [ AAA [ [ , [ [ ] ], [ [ AAR [ [ KgSOgfigoggHSS: gggggf prauh puuch OgigOmOBgaigOiti Uhf igObbOggOBge AAiAOgAHAARRAAAA? nfi gi^ mm:n-”ls11 sAAbRAAsRAAAssssssj nggggagggggggggggg iagsggOOOOgga a u -C nt i j-i 1 r highSpmddC>anfig upl i nl: Pears rCiritrul Cummin jAf AgSsAASR T rus~Cinf ig~Hl 11'4 hi ghSpsidC'in f i g-- '1 >: 1 E' crs-ChEs tMPDCCH-Cunf ig< ssOBRlOSAlsAs -- Meed OR oooooooo OPTIOHAL -- Meed OR OPTIOHAL -- MPkd OR BCCH-Confiq-vl31G OPTIOHAL, -- Meed OR PCCH-Config-vlolu OPTIOHAL, -- Meed OR FrqqHoppirigParaiiiqt qrs-rlB OPTIOHAL, -- Meed OR F DS C H - C o n f i g C o i tu! io n - v 1313 OPTIOHAL, -- Meed OR E'USCH-Corif igCC'niitiori-TlSlu OPTIOHAL, -- Need o pRACH-CgnfigSIE-visio OPTIOHAL, -- NPed OR PUCCH-ConfigCommon-vlElu RAiA|AARAAi -- Meed OR HighSpeedConfig-rl4 OPTIOHAL, -- Meed OR PRACH-Conf iq-’A14 30 OPTIOHAL, -- Heed OR OPTIOHAL -- Heed OR PRACH-ConfigSIE-vl5 SO OPTIOHAL, SMSMAS^dHdS RSS^cpnfiq^rlO OPTIOHAL, -- Need OR HU S-C o n f i g-r15 OPTIOHAL, -- Heed o HighSi:AedC'jnfig-’+lSSO OPTIOHAL -- NPed OR Up 1 i ri k pq r1? q n t r q 10 q 11 m iq n - v 1 3 3 0 iggiOlRII -- Heed OR WU 3 -' ? q ri f i g - ’ a1 5 6 0 OPTIOHAL -- Heed OR V TiJ 3 ~ C q n f i q ~ v 1 q 1 o OPTIOHAL, OR Hued dConf ig-vlul1: OPTIONAL, — He CRS-ChEstI IPDCCH-Ccnf igCummin-rlu OPT I ORAL AOAFlAAiA: punct urcdSubcarri ersDL-rl6 hl Th A dlnf~LRAT-HR-1 1 > OggOgaOgOggOOg p-upih-ToPui atim-rli pm ah-T DinAim-il" OPTIORAL Tend 1TT1T RadicRmui'ccCcnf igCimmin gsgogogf$0080® guggoqgf igOiObA: phiuh-Cunfig gwu a - Cu n f i g -1' 16 uplinl E '~i'’ nil 1' mm u- 1> I11 GHU S - C q ri f i g - r 16 OPTIOHAL, -- Heed OR OPTIOHAL, -- Heed OR EMUMERATED {enabled} OPTIOHAL, -- Heed o ENUMERATED {enabled} OPTIOHAL, OR PIT STRING {SEE (2)) -- Heed OR BOOLEAN OPTIOHAL -- Heed OR AAAOAAAiiRROAAASSSSS SEQUEHCE ( EIIUMERATED !unablld} ENUMERATED ( ms5uu, msluuu, m: P RAC H - T:: Du r a t i c n - r 1 ” PUCCH-T;:Duratiin-rl~ OgOsOOEgSgOsSgai SEQUENCE ( PDSCH-CcnfigCcmmin E'USCH-Conf igCommon PHICH-Cmfig OBAMAS ms 4 u u g}r OPTIORAL OPTIORAL sjgoioai soioAs SgTASRAA opgaaso Oga Oga OR OR OR OR AA OR OH OR TDD TDD3 TDD® TDD®: puceh-ConfigCommon A6dndiA|OdMl|C3Afl|C3fO u||in||dO|dOdf |131O^ ^ntenn.Wif-Common ||||||||||: || PUCCR-Cunf igCummuri 3 m u rid i n g R 3 - U L - C tn f i g C t mint’ n Up' 1 i n): P ome r C o n t r o 1' ? o mmc< n Antt n n a I n f c Cato up. n iDBssBiiiiiiiiiiiiiiiiiiiii CITI Cl IAL, OPTIOIIIL, CITI QI I AL, OPTIONAL, OE'TIOI IAL, OPTIOhAL, -- Hood Meed Meed Meed Heed OH OH OH OH Oi III CyclicPi'e f i::Lengt h UL-Cytlit Praf i::Length, ^111 >:::: upl i rd: Pc1 renCont no 1 Common-’'1 u Ju Up'liriliPt’i rtrCmtit t"lC"iTOii"ti-''lCC’? OPT I CI IAL -- Heed OH Biss ciO||||||||O EEBOBAOBBBiiBBEEEEEs lllllllllll -- Cond ii^B sjss pucch-ConfigCommon-vlJ"u PUCCH-Cunf igCAiimun-vlCCD lllllllllll -- Heed OR BB® BBst prech-Config-”! Siu :t::B:B®B:B:A:S:U®DS®i®iBt:t:t:t:t:t:t:t:t — Heed Oil B:fO|ldppin||dOO^ FregHoppingE'ar anietern-rl i APT I CI IAL, -- Heed Oi pd.: Ch^Conf igComhion~v / l 51U PD3CH~Cgnf igC-immAi-vl : ID CPTIC11AL, — OH punch-'A iif i g(^_ mm: n-”15111 PUCCH-Conf igCommon-vl nit CPTICI IAL, — Heed OH pucch^CohfigCohimon^ul Blu PUSCR-Canf igC'diiiTOin-viiiij OPTIOIIAL, -- Heed OH Bf p|||||pB|Sf Ipllf iiipo :: w:mp U 8g FUHO O OPT I CI IAL -- Heed OH BBC euI hi ghSpe e dCc n f i g - r 14 HighSp'ttidCorif ig-tll -- Heed OR pnech-Config-vl4 3 u PRA.CH-Cunf ig-vl 4 3D CPTICI IAL, -- Heed OR punch—Conf igCcmmon-vl 4 30 EIDCH - C-a n f 1 gC-amint ri - v 14 3 D OPT 101 IAL, — Heed OR tdd-Config-”l45u : UBIBBBBBBIBB IBB:::::::::: ||||i||A||| -- llOl: BBC Epi tdd-Conf ig-’rl 4 50 siB B B1®h Bigss® A BB?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:: -- Cond BBC BBst iiplmii] E 1 -11 ntr 1' mm n- 1r ” Up' 1 i ri 1: Ptn rt rCg tit r g 1C11toiit ti -' '1 5 ? C CPTICI IAL, — Heed OH highSpeedConfig^vl530 HighSppe-dCAnf ig-vl 533 OPTIOIIAL -- Heed OR BBC Elii h i g 1’13 pe e dCo n fig- v 1610 H i g h 3 p e e d C c< n f i g - v 1611J CPTICI IAL, -- Heed OR uplinlAowerCcritrol Common -vl 61 C> UpdinkPA rgrCgnt rt’lCATOiit’ri-vliElC APT I AI IAL, — Heed OR highOpeedlnt srUT-HR-rl 6 BBdOOOBBBBBBBBBBBBBBBBBBBB OPTIOIIAL -- Heed OH BBC ntn-ConfigCommon-rlT BdCPOhdhBBBBBBBBBBBBBBBBBB^ : :: : |d|R||d|||f 11:: : :::::::::::: JBBiBBB® 0 CPTICI IAL, — Heed llllill^lllillllllll ma Ei, insRij, msl<Jt>, ma 1A J, , msfuO, Illa ID DC, liiaiDDD, Illa 4 D D D, 136000}, prach-T::Durcticn-rl7 E' ARC H - T:: Du r a 11 o n - r 1 ~ CPTICI IAL, — Heed puc c h - T: :Du n j t i o n- r 1" PUCCH-Tv.Duvat ivn-rl” CPTICI IAL, — Heed OR puech-TuDurat ion-rl7 liiiiiiiiiiiiiiiiiiiiiiii PU 3 C H - T:: Du r a 11 -:> n - r 1" OPT I Cl LOL -- Heed OR B|| CToTAt||e|0^ :::: 0 :> :EE p:;.: i.-gp: n <<<0 gO g: g; g: Spec tent t'mittr-d . . . A3H13TI >P ; RadioResourceConfigCommon field descriptions ... Spec text omitted ... «78 ; The value of timer T318. Value msO corresponds with 0 ms, ms50 corresponds with 50 ms and so on. I ; ... Spec text omitted ... ----------------------Example based on 3GPP TS 36.331 V17.2.0---------------------- Figure 8 is a block diagram of an exemplary network entity that may be used in examples of the present disclosure. For example, a UE and / or gNB in the examples of Figures 1-7 may comprise an entity of Figure 8. 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 800 comprises a processor (or controller) 801, a transmitter 803 and a receiver 805. The receiver 805 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 803 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 801 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 examples 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. Certain examples of the present disclosure provide a method, for a first cell (e.g. a serving cell), for providing cell information (e.g. ephemeris information) of a second cell (e.g. a neighbouring cell), wherein the second cell is a Non Terrestrial Network (NTN) cell, the method comprising: transmitting, to a UE in the first cell, the cell information of the second cell, wherein the cell information of the second cell is transmitted: (i) using fewer bits, (ii) less frequently, and / or (iii) in more parts, than transmission, to the UE, of cell information of the first cell. In certain examples, transmitting the cell information of the second cell using fewer bits may comprise: transmitting at least a first portion of the cell information of the second cell (e.g. Common TA) using fewer bits than a corresponding portion of the cell information of the first cell. In certain examples, transmitting the cell information of the second cell using fewer bits may comprise: transmitting a second portion of the cell information of the second cell using the same number or more bits than a corresponding portion of the cell information of the first cell. In certain examples, transmitting the cell information of the second cell using fewer bits may comprise: transmitting at least a portion of the cell information of the second cell with lower accuracy (e.g. lower precision, lower granularity, higher coarseness) than the cell information of the first cell. In certain examples transmitting the cell information of the second cell using fewer bits may comprise: transmitting only a portion of the cell information of the second cell. In certain examples, transmitting the cell information of the second cell using fewer bits may comprise: transmitting at least a portion of the cell information of the second cell using a format (e.g. PVT format) and / or encoding different from the format and / or encoding used to transmit the cell information of the first cell. In certain examples, respective portions of the cell information of the second cell may be transmitted in respective Information Elements (lEs). In certain examples, the cell information of the second cell may be transmitted based on a network configuration (e.g. defining the total number of bits used to transmit the information and / or the number of bits used to define each parameter of the information). In certain examples, transmitting the cell information of the second cell less frequently may comprise: transmitting at least a portion of the cell information of the second cell in only some scheduled transmissions (e.g. SIB transmissions / SIB occasions). In certain examples, transmitting the cell information of the second cell using more parts may comprise: transmitting a first portion of the cell information of the second cell in a first System Information Block (SIB) (e.g. SIB 31); and transmitting a second portion of the cell information of the second cell in a second SIB (e.g. SIB other than SIB31). In certain examples, the method may further comprise obtaining (e.g. through system information, broadcast, dedicated signalling and / or in response to a request), by the UE, information defining one or more of: the identity of the SIBs including the first and second portions of the cell information of the second cell, the availability of the first and second SIBs, and the scheduling of the first and second SIBs. In certain examples, the cell information of the second cell may be transmitted according to one or more of: periodically, in response to a request (e.g. from the UE), through system information, through a broadcast transmission, through dedicated signalling. In certain examples, the method may further comprise: receiving, from the UE, an indication of a cell (e.g. the second cell); and in response to the indication, transmitting cell information of the indicated cell. In certain examples, the method may further comprise determining, by the UE, based on one or more certain criteria, a cell for which cell information is required. In certain examples, the one or more criteria may be based on one or more of: an amount of data in a buffer of the UE (e.g. whether an amount of data in the buffer exceeds a certain threshold), first cell signal strength (e.g. whether the signal strength of the first cell measured by the UE is below a certain threshold), which satellite serves the second cell (e.g. whether the second cell is served by a different satellite to the first cell). In certain examples, the first cell may be an NTN cell or a Terrestrial Network (TN) cell. Certain examples of the present disclosure provide a base station configured to perform a method according to any example, aspect, claim or embodiment disclosed herein. Certain examples of the present disclosure provide a network (or wireless communication system) comprising a base station and a UE according to any example, aspect, claim or embodiment disclosed herein. Certain examples of the present disclosure provide a computer program comprising 5 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, aspect, claim or embodiment disclosed herein. Certain examples of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to any example, aspect, claim or 10 embodiment disclosed herein. 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 acronyms / definitions are used. 3GPP 5G 3rd Generation Partnership Project 5th Generation 5 AMF Access and Mobility management Function AS Access Stratum CFRA Contention Free Random Access eMTC enhanced Machine Type Communication eNB Base Station 10 EPC Evolved Packet Core E-UTRAN Evolved Universal Terrestrial Radio Access Network GEO Geosynchronous Equatorial Orbit gNB 5G Base Station HAPS High Altitude Platform Station 15 ID Identity / ldentifi cation IE Information Element IMEISV International Mobile station Equipment Identity and Software Version loT Internet of Things LEO Lower Earth Orbit 20 LTE Long Term Evolution LTE-M LTE Machine Type Communication MAC Medium Access Control MDT Minimisation of Drive Test MME Mobility Management Entity 25 NB Narrow Band NG Next Generation NR New Radio NTN Non-Terrestrial Network PCI Physical Cell ID 30 PLMN Public Land Mobile Network ProSe Proximity-based Services RAN Radio Access Network RAT Radio Access Technology RLF Radio Link Failure 35 c-RNTI Cell Radio Network Temporary Identifier RRC Radio Resource Control RRM Radio Resource Management S-GW Serving Gateway SMF Session Management Function 40 SRVCC Single Radio Voice Call Continuity TS Technical Specification UE User Equipment UPF User Plane Function V2X Vehicle to Everything 45 X2 / Xn Interface between RAN nodes

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