WO2023186419A1

WO2023186419A1 - Wireless telecommunications apparatuses and methods

Info

Publication number: WO2023186419A1
Application number: PCT/EP2023/054743
Authority: WO
Inventors: Martin Warwick Beale; Samuel Asangbeng Atungsiri
Original assignee: Sony Europe BV United Kingdom Branch; Sony Group Corp
Current assignee: Sony Europe BV United Kingdom Branch; Sony Group Corp
Priority date: 2022-03-30
Filing date: 2023-02-24
Publication date: 2023-10-05
Anticipated expiration: 2024-09-30

Abstract

A wireless telecommunications apparatus for use with a non-terrestrial wireless telecommunications network, the wireless telecommunications apparatus comprising circuitry configured to receive ephemeris information of a satellite of the non-terrestrial wireless telecommunications network, a same version of the ephemeris information being repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information; wherein the plurality of SI windows is defined over an SI modification time period; and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

Description

WIRELESS TELECOMMUNICATIONS APPARATUSES AND METHODS

BACKGROUND

Field of the Disclosure

The present disclosure relates to wireless telecommunications apparatuses and methods.

Description of the Related Art

The “background” description provided is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in the background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

Recent generation mobile telecommunication systems, such as those based on the 3^rd Generation Partnership Project (3GPP (RTM)) defined Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE) and 5G New Radio (NR) architectures, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE and NR systems, a user can experience high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection.

In addition to supporting these kinds of more sophisticated services and devices, it is also proposed for newer generation mobile telecommunication systems such as NR to support less complex services and devices which make use of the reliable and wide ranging coverage of newer generation mobile telecommunication systems without necessarily needing to rely on the high data rates available in such systems. For example, a less complex device may be a tiny device equipped with sensors and a small battery capacity. Such a less complex device needs to transmit the sensor data at a typically infrequent and/or low data rate.

The demand to deploy such networks is therefore strong and there is a desire to improve the coverage area, performance and flexibility of these networks.

One example area of current interest includes so-called “non-terrestrial networks”, or NTNs for short. The 3GPP has proposed in, for example, Release 15 of the 3GPP specifications to develop technologies for providing coverage by means of one or more antennas mounted on an airborne or space-borne vehicle [1],

NTNs may provide service in areas that cannot be covered by terrestrial cellular networks (i.e. those where coverage is provided by means of land-based antennas), such as isolated or remote areas or on board aircraft or marine vessels, for example. NTNs may provide enhanced services in other areas. The expanded coverage that may be achieved using NTNs may provide, for example, improved service continuity for machine-to-machine (M2M) or ‘internet of things’ (loT) devices, or for passengers on board moving platforms (e.g. passenger vehicles such as aircraft, ships, high speed trains, buses or cars). Other benefits may arise from the use of NTNs for providing multicast I broadcast resources for data delivery.

The use of different types of network infrastructure equipment and requirements for coverage enhancement in NTN give rise to new challenges that need to be addressed.

SUMMARY

The present disclosure is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments and advantages of the present disclosure are explained with reference to the following detailed description taken in conjunction with the accompanying drawings, wherein:

Fig. 1 schematically represents some elements of an LTE-type wireless telecommunications system;

Fig. 2 schematically represents some elements of an NR-type wireless telecommunications system;

Fig. 3 schematically represents some components of the wireless telecommunications system shown in Fig. 2 in more detail;

Fig. 4 schematically illustrates a first example of an NTN architecture;

Fig. 5 schematically illustrates a second example of an NTN architecture;

Fig. 6 schematically shows a mapping of SIBs to SI messages, DL transport blocks and PDSCH;

Fig. 7 schematically shows an example of SIBs in SI messages in SI windows of a modification period according to an embodiment; and

Figs. 8A and 8B show flow charts showing methods according to embodiments.

Like reference numerals designate identical or corresponding parts throughout the drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution (LTE) Wireless Communications System

Fig. 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network I system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Fig. 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP body, and also described in many books on the subject, for example, Holma, H. and Toskala, A [2], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

The network 6 includes a plurality of base stations 1 connected to a core network 2. Each base station provides a coverage area 3 (i.e. a cell) within which data can be communicated to and from communications devices 4.

Although each base station 1 is shown in Fig. 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, interconnected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network.

Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. A communications device may also be referred to as a mobile station, user equipment (UE), user terminal, mobile radio, terminal device and so forth.

Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e. page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

A base station, which is an example of network infrastructure equipment, may also be referred to as a transceiver station, nodeB, e-nodeB (or eNodeB), eNB, g-nodeB (or gNodeB), gNB and so forth (note g-nodeB and gNB are related to 5G New Radio - see below). In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

In the present disclosure, any apparatus (e.g. communications device, infrastructure equipment and the like) which transmits and/or receives wireless telecommunications signals in any of the exemplified wireless telecommunication networks I systems may be referred to generally as a wireless telecommunications apparatus.

5G New Radio (NR) Wireless Communications System

An example configuration of a wireless communications network which uses some of the terminology proposed for NR is shown in Fig. 2. In Fig. 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41 , 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41 , 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to a core network 20 which may contain all other functions required for communicating data to and from the wireless communications devices and the core network 20. The core network 20 may be connected to other networks 300.

The elements of the wireless access network shown in Fig. 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Fig. 1 . It will be appreciated that operational aspects of the telecommunications network represented in Fig. 2 and of other networks discussed herein in accordance with embodiments of the disclosure which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

The TRPs 10 of Fig. 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated, therefore, that operational aspects of an NR network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of an NR network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

In terms of broad top-level functionality, the core network 20 connected to the NR telecommunications system represented in Fig. 2 may be broadly considered to correspond with the core network 2 represented in Fig. 1 , and the central unit 40 and associated DUs 41 , 42 / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Fig. 1 . The term network infrastructure equipment I access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the CU 40, DUs 41 , 42 and/or TRPs 10. Communications devices 14 are represented in Fig. 2 within the coverage area of respective communication cells 12. These communications devices 14 may thus exchange signalling with the CU 40 via the TRP 10 associated with their respective communication cells 12. A TRP 10 may be referred to as a gNodeB in NR.

It will further be appreciated that Fig. 2 represents merely one example of a proposed architecture for an NR-based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

Thus certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems I networks according to various different architectures, such as the example architectures shown in Figs. 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment I access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Fig. 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a CU 40, DU 41 , 42 and / or TRP 10 of the kind shown in Fig. 2 which is adapted to provide functionality in accordance with the principles described.

A more detailed diagram of some of the components of the network shown in Fig. 2 is provided by Fig. 3. In Fig. 3, a TRP 10 as shown in Fig. 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which is configured to control the transmitter 30 and the receiver 32 to transmit radio signals to and receive radio signals from one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Fig. 3, an example UE 14 is shown to include a corresponding wireless transmitter 49, wireless receiver 48 and a controller or controlling processor 44 which is configured to control the transmitter 49 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and the receiver 48 to receive downlink data as signals transmitted by the transmitter 30. The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance, for example, with the 5G/NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium.

As shown in Fig. 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

The interface 46 between the DU 42 and the CU 40 is known as the F1 interface which can be a physical or a logical interface. The F1 interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473 and, for example, may be formed from a fibre optic or other wired high bandwidth connection. In one example, the connection 16 from the TRP 10 to the DU 42 is fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP10 to the DU 42 and the F1 interface 46 from the DU 42 to the CU 40.

Non-Terrestrial Networks (NTNs)

An overview of NR-NTNs and their benefits can be found in [1], and some of the following description is based on this document to provide context for the present technique. Figs. 4 and 5 have also been reproduced from [1],

The benefits of NTNs (some of which are discussed above) may be applicable to NTNs operating alone or to NTNs integrated with terrestrial networks. They may impact at least coverage, user bandwidth, system capacity, service reliability or service availability, energy consumption and connection density. A role for NTN components in the 5G system is expected for at least the following verticals: transport, public safety, media and entertainment, eHealth, energy, agriculture, finance and automotive. It should also be noted that similar NTN benefits may apply when NTNs are used with 4G and/or LTE technologies and that, while NR is sometimes referred to in the present disclosure, the teachings and described techniques are equally applicable to 4G and/or LTE. In another example, [3] outlines a study carried out in 3GPP to adapt 3GPP Release 16 NB-loT (Narrowband Internet of Things) and eMTC (enhanced Machine Type Communication) for operation over NTN. Improved coverage enabled by NTNs is highly desirable for wide area loT services, for example. Fig. 4 illustrates a first example of an NTN architecture based on a satellite I aerial platform (which may be referred to as non-terrestrial infrastructure equipment) with a bent pipe payload, meaning that the same data is sent back down to Earth as is received by the satellite I aerial platform, with only frequency or amplification changing (i.e. acting like a pipe with a u-bend). In this example NTN, the satellite or the aerial platform will therefore relay a NR (or LTE) signal between the gNodeB (or eNodeB) and UEs in a transparent manner. In such examples, a UE may be considered to receive signals from the satellite, despite the fact that the signal originated from the gNodeB (or eNodeB) and that the satellite relays signals to the UE in a transparent manner.

Fig. 5 illustrates a second example of an NTN architecture based on a satellite I aerial platform (which, again, may also be referred to as non-terrestrial infrastructure equipment) comprising a gNodeB (or eNodeB). In this example NTN, the satellite or aerial platform carries a full or part of a gNodeB (or eNodeB) to transmit or receive an NR (or LTE) signal to or from the UE. For example, in addition to frequency conversion and amplification, the satellite I aerial platform may also decode a received signal. This requires the satellite or aerial platform to have sufficient onboard processing capabilities to be able to include gNodeB (or eNodeB) functionality, for example. Thus, for example, the satellite or aerial platform may comprise a transmitter 30, receiver 32 and controller 34 like those of TRP 10.

To ease uplink (UL) synchronization between a UE and an eNodeB/gNB in an NTN, the UE requires the following information:

• UE’s location on earth. This can be measured, for example, by global navigation satellite system (GNSS) circuitry (not shown) of the UE.

• The serving satellite’s position. This can be delivered to the UE via broadcast downlink (DL) information such as system information, for example. In another example, ephemeris information of the serving satellite that describes the orbital movement of the satellite is delivered to the UE. The UE can then use this to calculate the satellite location at a given time.

• For a situation like that exemplified in Fig. 4 (in which uplink signals from the UE are transmitted from the UE to the satellite and then from the satellite to the eNodeB/gNB), timing parameter(s) associated with the distance of the eNodeB/gNB from the satellite and frequency parameter(s) associated with Doppler shift due to the orbital movement of the satellite.

3GPP RAN 1 has agreed that the ephemeris information shall be broadcast to UEs via system information. The detailed orbit of a satellite is not, however, long-term predictable. This means that the ephemeris information of the satellite has a life-span and so must be updated at regular intervals. Once established for a given cell, transmission of system information (SI) is repeated at regular intervals and/or delivered to the UE on demand (e.g. in NR). The repetition of SI allows any UE to decode the SI from the DL signal whenever it needs it. When the SI changes, there are several existing mechanisms to notify the UE that the SI has changed. In this case, having received notification that the SI has changed, a UE therefore re-reads the SI when it needs to configure anything in accordance with an SI parameter. In order words, a UE having read the SI once, for example during initial access, is not expected to read the SI again unless it has received notification that the SI has changed. This helps the UE to save battery power.

In NTN, the ephemeris information is repeatedly broadcast on SI for any UE in need of the information to read. Since the ephemeris information becomes stale and needs to be updated, it is useful for a UE that reads the information to also know for how much longer that information will remain valid. This is especially useful, for example, to RRC-IDLE and RRC-INACTIVE mode UEs to avoid unnecessary re-reads of the SI to ensure the ephemeris information they store is still valid (for example, the RRC-IDLE or RRC-INACTIVE UE only needs to re-read the SI when it knows the ephemeris information has expired). For similar reasons, this is also useful for RRC-CONNECTED mode UEs implementing DRX (discontinuous reception) or a handover process, for example.

The UE needs to apply timing and frequency compensation to its UL transmissions.

The timing compensation allows the UE to compensate for the propagation distance between the UE and satellite. Timing compensation can take the form of the UE applying a timing advance to UL transmissions, for example.

The frequency compensation allows the UE to compensate for frequency errors, for example due to Doppler shift between the UE and the satellite because of the orbital speed of the satellite. The frequency compensation can take the form of applying an equal and opposite frequency offset to the frequency error caused by the Doppler shift, for example.

In order to apply timing and frequency compensation, the UE needs to know the propagation time and relative velocity between the UE and the satellite. The UE is able to calculate these parameters based on the following, for example:

• The UE knows its own location, e.g. through GNSS measurements.

• The location of the satellite is known by the satellite ground station. The satellite location will be known through a GNSS receiver on the satellite or through orbital calculations, for example.

The location of the satellite is signalled to the UE within ephemeris information. The ephemeris information can be signalled either as orbital information of the satellite, according to known orbital equations, or as position and velocity information of the satellite. The ephemeris information is signalled in system information transmitted by the network (e.g. by the satellite itself or by a terrestrial eNodeB or gNodeB of the network). The system information (SI) is carried in broadcast messages in system information blocks (SIBs) that are carried within SI messages and carried on a physical downlink shared channel (PDSCH). That is:

• System information blocks (SIBs) are radio resource control (RRC) messages

• One or more SIBs are multiplexed into a system information message (SI message)

• The SI message is transmitted as a transport block on PDSCH.

The ephemeris information changes with time. Although it might be natural to think that the orbit of a satellite can be predicted for a long period of time by using the equations of motion that are well known from physics, this is not really the case. The orbits of satellites cannot be accurately predicted over long intervals due to various issues, including, for example:

• Rocket burns

• Drag from residual atmosphere in space

• Perturbations in the orbit due to gravitational forces that are not modelled in the orbital equations (e.g. the orbital equations might not take into account the gravitational attraction due to mountain ranges on earth or due to other planets).

Hence, the ephemeris information will change. The ephemeris information can change reasonably quickly (e.g. every several seconds, such as over intervals of the order 1 or 10 seconds). The UE interpolates (e.g. via known equations) the position and velocity of the satellite between instances of the ephemeris information. The ephemeris information hence needs to indicate values of the orbital parameters (e.g. satellite position and velocity) at a certain time. This is referred to as the epoch time (and the UE therefore interpolates the satellite position and velocity between successive epoch times). The epoch time can be signalled either implicitly or explicitly. In explicit signalling, the epoch time is signalled via an information element (IE) within an RRC message transmitted either by SIB signalling or dedicated RRC signalling, for example. In implicit signalling, the epoch time is known implicitly. For example, the epoch time may be implicitly known as being the time of the end of an SI window within which the ephemeris information is initially signalled.

An example of the parameters comprised in the ephemeris information is given in Table 7.3.6.1- 1 of [4],

The coverage conditions of NTN can be poor due to the long propagation distances involved. The SNR (signal-to-noise ratio) observed at the UE can hence be low (e.g. of the order of - 15dB) [5], In order to operate at such low SNRs, the system information may need to be repeated many times. The UE can soft-combine the repeated SIB transmissions. The problem with repeating SIB transmissions, however, is that it uses up a lot of system resources. When the UE does soft-combining, it combines the LLRs (log likelihood ratios) of transmissions that contain the same transport bits. Combining can either be chase combining when the same physical bits are transmitted in all repetitions or incremental redundancy when different physical bits are transmitted in each repetition.

Fig. 6 shows the mapping of SIBs to SI messages, DL transport blocks and PDSCH. The figure shows that multiple SIBs can be mapped to a single SI message. It is also possible that a single SIB is mapped to a single SI message (and then to a DL transport block and PDSCH). This concept is also explained in [6] and [8], for example.

[6] also explains the transmission of SI messages within SI windows for LTE (other than LTE-M I eMTC or NB-loT). An SI window is a periodically-occurring time-domain window in which a particular SI message may be transmitted. Each SI message has its own respective SI window and the SI windows of all SI messages form a periodically-repeating cluster. Each SI window appears once in the cluster and the SI windows in the cluster are consecutive (that is, nonoverlapping and without gaps between them) and of a common, configurable length. As explained in [6], for LTE (other than LTE-M or NB-loT), physical layer control signalling (e.g. transmitted in the physical downlink control channel, PDCCH) schedules which specific subframe(s) within an SI window are actually used for transmission of its corresponding SI message.

The use of SI windows in LTE-M (LTE-MTC, that is, LTE Machine Type Communication) is different. In particular, the PDSCH conveying SI message(s) are not scheduled by PDCCH (or MPDCCH, that is, MTC PDCCH) in LTE-M. Rather, the PDSCH conveying SI message(s) are transmitted at known locations (in the time I frequency space) and with known characteristics (e.g. in terms of transport block size). A description of the transmission of SI messages in LTE- M is provided in [7], for example. Here, a particular SI message is still transmitted in a corresponding SI window. However, the subframe(s) within that SI window used to transmit that SI message are not scheduled by PDCCH (or MPDCCH). Rather, they are semi-statically scheduled via signalling in SIB1 , for example.

Transmission of SI messages (whether scheduled by PDCCH or semi-statically scheduled by SIB1) may be repeated within a single SI window. This is useful for coverage extension, for example. Coverage extension can be applied by reducing the periodicity of the SI messages (so the SI messages are transmitted with a shorter gap between them) within the SI window and increasing the number of repetitions of the SI message within the SI window.

In embodiments, the number of “repetitions” may be one or more. Thus, for example, there can be one repetition (meaning, for example, an SI message is transmitted a single time), two repetitions (meaning, for example, the same SI message is transmitted twice), three repetitions (meaning, for example, the same SI message is transmitted three times), and so on.

There are limitations to this coverage extension scheme, however. For example, for semi- statically scheduled SI messages, all SI messages have the same repetition pattern (that is, the nth SI message transmitted in the nth repeating SI window will have the same repeating pattern within that SI window as the n+7th SI message in the n+7th repeating SI window). However, some SI messages do not need more repetitions within the SI window. For example, it may be desirable for SI messages that change frequently (e.g. those indicating ephemeris information) to have many repetitions within a single SI window for coverage extension, since the information indicated by them may have changed by the time the SI window is repeated. On the other hand, for other SI messages that do not change frequently (or at all), it is sufficient to provide sufficient repetitions over any or all SI windows over a given time period (known as the modification period - see below) to provide coverage extension (since it can be guaranteed that the information indicated by the SI message will not have changed by the time the SI window is repeated). As previously discussed, coverage enhancement for SI messages can be achieved by soft-combining between receptions of those SI messages only when those SI messages consist of the same information

In other words, the information carried in SI messages often does not change during a period of time known as the modification period. There are multiple SI windows within the modification period. Hence, as indicated above, a UE can achieve coverage enhancement by soft-combining transport blocks carrying the SI message between any or all repetitions of the relevant SI window in the modification period (e.g. the UE can combine a reception of SIB_X in SI Window M with a reception of the same SIB_X in SI Window N, as long as Window M and Window N are in the same modification period).

However, this is only applicable for SI messages which carry information which does not change during the modification period. For SI messages carrying information which does change during the modification period (e.g. an SI message transmitting ephemeris information, which may change more frequently than the modification period for the reasons of inaccuracy of orbital prediction described above), the content of the SI message may change between repetitions of the relevant SI window, even when those repetitions are within the same modification period. Hence, the UE cannot rely on combining repetitions of such an SI message in any SI window of the modification period.

As discussed, one solution to the coverage enhancement issue is to instead combine repetitions of an SI message in the same SI window (assuming the information of the SI message stays the same during a single instance of the relevant SI window). However, in implementations such as LTE-M, all SI windows have the same repetition pattern, meaning that a high number of repetitions of one SI message in a single SI window requires all other SI messages to also have that high number of repetitions in their respective SI windows. This is not necessary for all SI messages (e.g. those carrying information which remains the same throughout the modification period), however, and thus results in an inefficient use of radio resources.

It is therefore desirable to improve the coverage of NTN ephemeris signalling in system information without leading to excessive use of resources for the signalling of other system information. The present technique helps address this by enabling the NTN ephemeris information to be signalled with a faster update rate than for other system information. In an example of the present technique, an SI message carrying a SIB carrying first ephemeris information (a SIB carrying ephemeris information may be referred to as a SIB-EPH) is repeated across more than one SI Window within the modification period. The first ephemeris information does not change between the SI windows concerned. The SI message is not, however, repeated across all SI windows of the modification period. Rather, during the modification period, the first ephemeris information is updated to second ephemeris information. At least one SI window of the modification period is therefore used for transmission of an SI message carrying a SIB carrying the second ephemeris information.

Thus, the number of SI windows over which the same SI message carrying SIB-EPH is repeated is greater than one but less than the total number of SI windows carrying SIB-EPH within the modification period (since the ephemeris information carried by SIB-EPH may change during the modification period). The UE can soft-combine the repeated SI messages between the SI Windows, hence improving coverage for receiving the ephemeris information and with less waste of radio resources (compared, for example, to repeating all SI messages with the same repetition pattern in all SI windows).

This is exemplified in Fig. 7. Here, a modification period 700 is shown comprising several clusters of SI windows. In particular, there is a first cluster 701 A comprising SI windows 702A, 703A and 704A, a second cluster 701 B comprising SI windows 702B, 703B and 704B and a third cluster 701 C comprising SI windows 702C, 703C and 704C. For simplicity, only three clusters are shown here. In reality, there may be more. The SI windows 702A, 702B and 702C are repeating instances of an SI window in which an SI message comprising SIB-EPH is transmitted to the UE. The SI windows 703A, 703B and 703C and the SI windows 704A, 704B and 704C are repeating instances of SI windows in which other SI messages 705 are transmitted to the UE. The information carried by the other SI messages 705 remains the same throughout the modification period 700. On the other hand, the ephemeris information changes during the modification period 700. In particular, it changes between transmission of SIB-EPH in cluster 701 B and the transmission of SIB-EPH in cluster 701 C. Thus, an SI message carrying a SIB carrying first ephemeris information (SIB-EPH 1) is transmitted in clusters 701 A and 701 B and an SI message carrying a SIB carrying second, updated, ephemeris information (SIB-EPH 2) is transmitted in cluster 701 C, even though clusters 701 A, 701 B and 701 C are all within the same modification period.

The UE needs to know which SI messages within the modification period comprise the same ephemeris information in order to successfully soft-combine SIB-EPH in those SI messages to achieve coverage extension.

The UE may explicitly know which SI windows in the modification period carry the same SIB- EPH.

In one example, SIB1 signals which SI windows contain the same SIB-EPH within a given modification period. For example, SIB1 could indicate that groups of 4 consecutive SI windows carrying SIB-EPH contain the same SIB-EPH. Alternatively, SIB1 may signal (e.g. in a cell specific manner) the number of consecutive SI windows carrying SIB-EPH from the beginning of the SI modification period over which SIB-EPH remains the same. Consecutive SI windows carrying SIB-EPH may be interleaved with other SI windows carrying other SI messages, as exemplified in Fig. 7. Thus, for example, in Fig. 7, SI windows 702A, 702B and 702C are consecutive SI windows carrying SIB-EPH (with SIB-EPH remaining the same for SI windows 702A and 702B but changing for SI window 702C) even though they are interleaved with other SI windows 703A, 704A, 703B, 704B, etc.

In another example, PDCCH signalling (e.g. via MPDDCH I NPDCCH (narrowband PDCCH)) can signal whether the PDSCH transmitting the current SI message carrying SIB-EPH can be combined with the previous PDSCH that transmitted the SI message carrying SIB-EPH. An example of such signalling is to use the toggling New Data Indicator (NDI) bit. For example, if NDI does not toggle (that is, remains the same as the previously received NDI bit), the UE determines it can combine the current PDSCH containing the SI message carrying SIB-EPH with the previous PDSCH containing the SI message carrying SIB-EPH. On the other, if the NDI does toggle (that is, it is different to the previously received NDI bit), the UE determines SIB- EPH has changed and therefore it cannot combine the current PDSCH containing the SI message carrying SIB-EPH with the previous PDSCH containing the SI message carrying SIB- EPH. While PDSCH carrying SIB is not allocated by MPDCCH I NPDCCH for eMTC I NB-loT in terrestrial networks, it may be allocated by MPDCCH I NPDCCH in NTNs in this example. The PDCCH may carry a compact DCI (downlink control information) which indicates (e.g. via the NDI bit described above) at least whether or not it is possible to combine the current PDSCH with the previous PDSCH for coverage enhancement (this depending on whether SIB-EPH has changed or not), for example.

In another example, a value tag within SIB1 indicates whether SIB-EPH has changed. For instance, in order to read SIB-EPH, the UE may first decode SIB1 in order to decide whether the current PDSCH carrying SIB-EPH could be soft-combined with the previous PDSCH carrying SIB-EPH. If SIB1 indicates SIB-EPH has changed, then such soft-combining is not possible (whereas if SIB1 indicates that SIB-EPH has not changed, then such soft-combining is possible). Alternatively, if SIB1 is not decoded first, the UE may instead soft-combine the current PDSCH carrying SIB-EPH with the previous PDSCH carrying SIB-EPH regardless of the status of SIB1 . SIB1 is then decoded and, if the value tag has changed, the soft-combining HARQ buffer for that PDSCH is then cleared. In either case, the UE thus reads the value tag within SIB1 within the modification period to determine whether SIB-EPH has changed.

The UE may implicitly assume how many SI windows in the modification period carry the same SIB-EPH.

In one example, the UE measures the quality (e.g. reference signal received quality, RSRQ) and/or strength (e.g. reference signal received power, RSRP) of received signals from the network (RSRP is mentioned in the following examples, however, where applicable, RSRQ may be used instead or additionally). For example, it calculates the RSRP of a downlink signal or the number of attempts required to decode the physical broadcast channel PBCH (with higher number of attempts being required when the signal quality and/or strength is lower). Based on the measured signal quality, the UE then estimates the number of repetitions (that is, the number of consecutive SI windows carrying the same SIB-EPH) required to decode SIB-EPH. The UE then attempts to decode SIB-EPH based on that number of repetitions. In this example, the network is aware of the worst case coverage conditions at the UE (knowing the worst case path loss between the satellite and any UE within the coverage area of the satellite) and sets an appropriate number of repetitions that will allow SIB-EPH to be decoded by the UE. There is therefore no need for the network to explicitly signal the number of consecutive SI Windows in the modification period carrying the same SIB-EPH.

In an example, the network determines the expected RSRP conditions at the UE (and therefore the appropriate number of SIB-EPH repetitions) based on, for instance, a-priori knowledge of the system parameters (such as path loss from satellite to ground, the transmit power of satellite, etc.) Such system parameters may be more reliably predictable for NTNs compared to terrestrial networks due to, for example, the space between the UE and the satellite being mostly open sky (and there thus being less chance of unpredictable RSRP variations due to obstacles between the UE and satellite).

In another example, the network requests RSRP measurements from UEs in the cell and, based on these RSRP measurements, determines an appropriate number of times that transmission of the same SIB-EPH should be repeated. In an example, since the network can only request RSRP measurements from UEs that have previously successfully connected to the cell, the RSRP measurements received from such UEs can be used to estimate the RSRP measurements of UEs that have not yet successfully connected. For example, the average of the RSRP measurements reported by all UEs connected to the cell may be taken as representative of the RSRP of UEs not yet successfully connected. This then indicates the number of repetitions of the same SIB-EPH likely to be required for those UEs to connect (with, in general, a higher RSRP meaning fewer SIB-EPH repetitions are required and a lower RSRP meaning more SIB-EPH repetitions are required).

In another example, the network may determine the UE path loss based on the measured reception power of SRS (sounding reference signal) or PRACH (physical random access channel) preamble transmissions from UE(s). The network may then use such measurements to determine the necessary number of SIB-EPH repetitions.

The number of times that the same SIB-EPH is repeated may be preconfigured in the specification(s) depending on, for example, the orbit of the satellite. For example, more repetitions of SIB-EPH may be specified for a GEO satellite than for a LEO satellite. GEO satellites are further away from earth than LEO satellites and, thus, this is based on the assumption that the path loss to the GEO satellite is greater than the path loss to a LEO satellite.

The UE may blind decode the SIB-EPH based on different hypotheses of the number of times the transmission of the same SIB-EPH is repeated. For example, the UE may make an initial assumption of the number of times that the same SIB-EPH is repeated based on measured RSRP (as previously discussed) and attempt to decode based on this number of repetitions. If the UE is unable to decode SIB-EPH, the UE then changes the assumption of the number of SIB-EPH repetitions.

For instance, if the UE fails to decode the SIB-EPH based on an initial assumption of the number of repetitions of the same SIB-EPH (e.g. 4 repetitions), it may attempt to decode based on a higher assumed number of repetitions (e.g. 8 repetitions) if, for example, the assumption is the SNR may have been too low and/or based on a lower assumed number of repetitions (e.g. 2 repetitions) if, for example, the assumption is the SIB-EPH changed during the decoding based on the initial assumed number of SIB-EPH repetitions. Either scenario (that is, decoding based on an insufficient number of repetitions due to a low SNR or decoding based on too high a number of repetitions such that the SIB-EPH is changed at some time during the repetitions) may lead to a failure in successfully decoding SIB-EPH and, thus, the UE attempting to decode based on a different number of repetitions may help overcome this problem. In an example, the network is compelled to choose from amongst a predetermined set of repetition factors for transmission of the same SIB-EPH, for example {1 ,2, 4, 6, 8}. This limits the number of possibilities that the UE has to blindly try to decode. In the example set {1 ,2, 4, 6, 8}, the UE may, for example, first attempt decoding based on 4 repetitions and, failing this, successively attempt decoding based on 6, 2, 8 and 1 repetitions.

In an example, once the UE has successfully decoded SIB-EPH (e.g. according to one of the above embodiments), the UE assumes the same number of SIB-EPH repetitions when it attempts to decode an updated SIB-EPH in the future (either during its current connection or in a future connection with the satellite or with another satellite of the same constellation). This works when, for example, the UE connects to the same satellite constellation and SIB-EPH is transmitted similarly (e.g. with a consistent number of repetitions of the same SIB-EPH in each satellite of the constellation).

In another example, a successfully decoded SIB-EPH (or another suitable NTN SIB) indicates the number of repetitions of a given SIB-EPH that can be accumulated for different satellites in a constellation. The UE initially estimates the number of repetitions according to, for example, one of the above embodiments in order to read SIB-EPH. After having read SIB-EPH, the UE then knows the characteristics (including the number of repetitions of the same SIB-EPH) by which SIB-EPH is transmitted by other satellites in the constellation (and can thus successfully decode updated SIB-EPHs when required from any of those satellites in the future). This is useful if, for example, different satellites in a constellation transmit at different transmit powers and thus may transmit different numbers of repetitions of SIB-EPH (with, for example, a lower power satellite transmitting more repetitions of a given SIB-EPH and a higher power satellite transmitting fewer repetitions of a given SIB-EPH). For example, some satellites may be older and hence lower powered or some satellites may have damaged solar panels and can hence only transmit at a lower power). Also, some NTNs may operate with satellites with different orbital heights, for example an NTN incorporating both GEO and NGSO satellites. Satellites in higher orbits may require more repetitions than satellites in lower orbits, for example. By the UE estimating which satellite it will connect to (e.g. based on some rough almanac information), the UE can then use the list of characteristics of that satellite (including the number of repetitions for a given SIB- EPH) indicated by the initially received SIB-EPH to determine the number of SIB-EPH repetitions associated with that satellite.

In the above examples (and as previously explained), the number of physical layer repetitions (e.g. PDSCH repetitions) carrying SIB in an SI window may be fixed for all SIBs (so all SI windows for all SIBs have the same number of repetitions of the SIB). For example, this is the case for eMTC. However, since not all SIBs change as often as SIB-EPH (but will still be repeated for the same number of times in their respective SI windows as SIB-EPH in its SI window), this leads to a waste of system resources. Thus, in another example, physical layer repetitions (e.g. PDSCH repetitions) of SIB-EPH in its SI window may be greater than the number of physical layer repetitions (e.g. PDSCH repetitions) of other SIBs in their respective SI windows, even in, for example, eMTC. This allows, for example, a first number (e.g. 4) of SIB- EPH repetitions in the SIB-EPH SI window (e.g. SI windows 702A, 702B and 702C) and a second, smaller number (e.g. 2) of repetitions of other SIBs in their respective SI windows (e.g. SI windows 703A, 704A, 703B, 704B, 703C, 704C). This allows a sufficient number of repetitions of the same SIB-EPH to be received by the UE (thereby allowing the UE to decode that SIB-EPH and obtain the latest ephemeris information) before SIB-EPH changes (SIB-EPH changing within the modification period) whilst freeing up resources that would otherwise have been unnecessarily used with repetitions of other SIBs (which do not change within the modification period).

Fig. 8A shows a method carried out by a wireless telecommunications apparatus (e.g. UE 14) according to an embodiment.

The method starts at step 800.

At step 801 , the wireless telecommunications apparatus is controlled (e.g. by controller 44) to receive (e.g. via receiver 48) ephemeris information of a satellite of the non-terrestrial wireless telecommunications network.

In one example, a same version of the ephemeris information is repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information. The plurality of SI windows is defined over an SI modification time period and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period. This is exemplified in Fig. 7, for example, SIB-EPH SI windows 702A, 702B and 702C are defined over SI modification time period 700 but only a subset of these SI windows (namely, SI windows 702A and 702B) contain the same version of the ephemeris information (that is, SIB-EPH 1). The other SI window 702C (namely, SI window 702C) contains a different version of the ephemeris information (that is, SIB-EPH 2) since, during the SI modification period, the ephemeris information has been updated. In another example, the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times. Other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times. The second number is less than the first number. This allows, for example, each of the SI windows 702A, 702B and 702C to transmit multiple repetitions of SIB-EPH (e.g. two repetitions of SIB-EPH 1 within each of SI windows 702A and 702B, two repetitions of SIB-EPH 2 within SI window 702C) while maintaining only a single repetition of other system information 705 within each of the other SI windows. This allows, for example, greater repetition of certain types of system information which require such repetition (ephemeris information, in this case) without the need for that repetition to be applied to all system information. Resource wastage is thus alleviated. This helps address the problem of inflexibility when, for example, all SI windows have the same repeating pattern of SI messages when SI messages are semi-statically scheduled (e.g. as in LTE-M).

The method ends at step 802.

Fig. 8B shows another method carried out by a wireless telecommunications apparatus (e.g. TRP 10, such as an eNB or gNB) according to an embodiment. The wireless telecommunications apparatus may be comprised in terrestrial infrastructure equipment (e.g. land-based eNB or gNB) or non-terrestrial infrastructure equipment (e.g. a satellite), for example. The method of Fig. 8B is the corresponding transmission side method to the reception side method of Fig. 8A.

The method starts at step 803.

At step 804, the wireless telecommunications apparatus is controlled (e.g. by controller 34) to transmit (e.g. via transmitter 30) ephemeris information of a satellite of the non-terrestrial wireless telecommunications network.

Again, in one example, a same version of the ephemeris information is repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information. The plurality of SI windows is defined over an SI modification time period and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

In another example, the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times. Other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times. The second number is less than the first number.

The method ends at step 805. Embodiment(s) of the present disclosure are defined by the following numbered clauses:

1 . A wireless telecommunications apparatus for use with a non-terrestrial wireless telecommunications network, the wireless telecommunications apparatus comprising circuitry configured to receive ephemeris information of a satellite of the non-terrestrial wireless telecommunications network, a same version of the ephemeris information being repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information; wherein the plurality of SI windows is defined over an SI modification time period; and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

2. A wireless telecommunications apparatus according to clause 1 , wherein the circuitry is configured to soft-combine the repeatedly received same version of the ephemeris information.

3. A wireless telecommunications apparatus according to clause 1 or 2, wherein the circuitry is configured to receive a signal indicating the subset of the plurality of SI windows.

4. A wireless telecommunications apparatus according to clause 3, wherein the signal is a system information block 1 , SIB1 , signal.

5. A wireless telecommunications apparatus according to clause 3, wherein the signal is a downlink control information, DCI, signal carried on a physical downlink control channel, PDCCH.

6. A wireless telecommunications apparatus according to clause 1 or 2, wherein the circuitry is configured to determine the subset of the plurality of SI windows based on a measured quality and/or strength of signals received from the network by the wireless telecommunications apparatus and/or another wireless telecommunications apparatus.

7. A wireless telecommunications apparatus according to clause 1 or 2, wherein the subset of the plurality of SI windows is preconfigured.

8. A wireless telecommunications apparatus according to clause 1 or 2, wherein the circuitry is configured to: soft-combine ephemeris information in a first number of consecutive SI windows of the plurality of SI windows; determine whether the soft-combining is successful; and if the soft-combining is successful, determine the first number of consecutive SI windows as the subset of the plurality of SI windows.

9. A wireless telecommunications apparatus according to clause 8, wherein: the first number is one of a plurality predetermined numbers; and the circuitry is configured to attempt to soft-combine ephemeris information in a number of consecutive SI windows of the plurality of SI windows corresponding to each of the plurality of predetermined numbers until the soft-combining is successful.

10. A wireless telecommunications apparatus according to any preceding clause, wherein the number of SI windows in the subset of the plurality of SI windows is the same for a plurality of different satellites.

11. A wireless telecommunications apparatus according to any preceding clause, wherein the number of SI windows in the subset of the plurality of SI windows is different for a plurality of different satellites and is indicated, for each of the satellites, in a system information block, SIB, carrying the ephemeris information.

12. A wireless telecommunications apparatus for use with a non-terrestrial wireless telecommunications network, the wireless telecommunications apparatus comprising circuitry configured to receive ephemeris information of a satellite of the non-terrestrial wireless telecommunications network, wherein: the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times; and other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times, the second number being less than the first number.

13. A wireless telecommunications apparatus for use with a non-terrestrial wireless telecommunications network, the wireless telecommunications apparatus comprising circuitry configured to transmit ephemeris information of a satellite of the non-terrestrial wireless telecommunications network, a same version of the ephemeris information being repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information; wherein the plurality of SI windows is defined over an SI modification time period; and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

14. A wireless telecommunications apparatus according to clause 13, wherein the circuitry is configured to transmit a signal indicating the subset of the plurality of SI windows.

15. A wireless telecommunications apparatus according to clause 14, wherein the signal is a system information block 1 , SIB1 , signal.

16. A wireless telecommunications apparatus according to clause 14, wherein the signal is a downlink control information, DCI, signal carried on a physical downlink control channel, PDCCH. 17. A wireless telecommunications apparatus according to clause 13, wherein the circuitry is configured to determine the subset of the plurality of SI windows based on a measured quality and/or strength of signals received from the network by another wireless telecommunications apparatus.

18. A wireless telecommunications apparatus according to clause 13, wherein the subset of the plurality of SI windows is preconfigured.

19. A wireless telecommunications apparatus according to any one of clauses 13 to 18, wherein the number of SI windows in the subset of the plurality of SI windows is the same for a plurality of different satellites.

20. A wireless telecommunications apparatus according to any one of clauses 13 to 19, wherein the number of SI windows in the subset of the plurality of SI windows is different for a plurality of different satellites and is indicated, for each of the satellites, in a system information block, SIB, carrying the ephemeris information.

21 . A wireless telecommunications apparatus for use with a non-terrestrial wireless telecommunications network, the wireless telecommunications apparatus comprising circuitry configured to transmit ephemeris information of a satellite of the non-terrestrial wireless telecommunications network, wherein: the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times; and other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times, the second number being less than the first number.

22. A method of controlling a wireless telecommunications apparatus for use with a nonterrestrial wireless telecommunications network, the method comprising controlling the wireless telecommunications apparatus to receive ephemeris information of a satellite of the nonterrestrial wireless telecommunications network, a same version of the ephemeris information being repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information; wherein the plurality of SI windows is defined over an SI modification time period; and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

23. A method of controlling a wireless telecommunications apparatus for use with a nonterrestrial wireless telecommunications network, the method comprising controlling the wireless telecommunications apparatus to receive ephemeris information of a satellite of the nonterrestrial wireless telecommunications network, wherein: the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times; and other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times, the second number being less than the first number.

24. A method of controlling a wireless telecommunications apparatus for use with a nonterrestrial wireless telecommunications network, the method comprising controlling the wireless telecommunications apparatus to transmit ephemeris information of a satellite of the nonterrestrial wireless telecommunications network, a same version of the ephemeris information being repeatedly transmitted in only a subset of a plurality of system information, SI, windows for transmitting the ephemeris information; wherein the plurality of SI windows is defined over an SI modification time period; and the subset of the plurality of SI windows is defined over a time period shorter than the SI modification time period.

25. A method of controlling a wireless telecommunications apparatus for use with a nonterrestrial wireless telecommunications network, the method comprising controlling the wireless telecommunications apparatus to transmit ephemeris information of a satellite of the nonterrestrial wireless telecommunications network, wherein: the ephemeris information is repeatedly transmitted as semi-statically scheduled first system information in a first system information, SI, window a first number of times; and other system information is repeatedly transmitted as semi-statically scheduled second system information in a second, different, SI window a second number of times, the second number being less than the first number.

26. A program for controlling a computer to perform a method according to any one of clauses 22 to 25.

27. A storage medium storing a program according to clause 26.

Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that, within the scope of the claims, the disclosure may be practiced otherwise than as specifically described herein.

In so far as embodiments of the disclosure have been described as being implemented, at least in part, by one or more software-controlled information processing apparatuses, it will be appreciated that a machine-readable medium (in particular, a non-transitory machine-readable medium) carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure. In particular, the present disclosure should be understood to include a non-transitory storage medium comprising code components which cause a computer to perform any of the disclosed method(s).

It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and/or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and/or processors may be used without detracting from the embodiments.

Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more computer processors (e.g. data processors and/or digital signal processors). The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and/or processors.

Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to these embodiments. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in any manner suitable to implement the present disclosure.

REFERENCES

[1] TR 38.811 , “Study on New Radio (NR) to support non terrestrial networks (Release 15)”, 3rd Generation Partnership Project, December 2017.

[2] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[3] TR 36.763, “Study on Narrow-Band Internet of Things (NB-loT) I enhanced Machine Type Communication (eMTC) support for Non-Terrestrial Networks (NTN) (Release 17)”, 3rd Generation Partnership Project, June 2021.

[4] TR 38.821 , “Solutions for NR to support non-terrestrial networks (NTN) (Release 16)”, 3rd Generation Partnership Project, May 2021.

[5] R1-2105182. “loT-NTN Link Budgets”. Sony. RAN1#105e. May 2021.

[6] “LTE: The UMTS long term evolution”. Section 3.2.2. Sesia, Toufik, Baker et al. pp59-62

[7] “Cellular Internet of Things. First Edition”. Section 5.1 .3.2. Liberg, Sunderberg, Bergman et al.

[8] https://howltestuffworks.bloQspot.com/2019/10/5Q-nr-system-information.html 1

Claims

2. A wireless telecommunications apparatus according to claim 1 , wherein the circuitry is configured to soft-combine the repeatedly received same version of the ephemeris information.

3. A wireless telecommunications apparatus according to claim 1 , wherein the circuitry is configured to receive a signal indicating the subset of the plurality of SI windows.

4. A wireless telecommunications apparatus according to claim 3, wherein the signal is a system information block 1 , SIB1 , signal.

5. A wireless telecommunications apparatus according to claim 3, wherein the signal is a downlink control information, DCI, signal carried on a physical downlink control channel, PDCCH.

6. A wireless telecommunications apparatus according to claim 1 , wherein the circuitry is configured to determine the subset of the plurality of SI windows based on a measured quality and/or strength of signals received from the network by the wireless telecommunications apparatus and/or another wireless telecommunications apparatus.

7. A wireless telecommunications apparatus according to claim 1 , wherein the subset of the plurality of SI windows is preconfigured.

8. A wireless telecommunications apparatus according to claim 1 , wherein the circuitry is configured to: soft-combine ephemeris information in a first number of consecutive SI windows of the plurality of SI windows; determine whether the soft-combining is successful; and if the soft-combining is successful, determine the first number of consecutive SI windows as the subset of the plurality of SI windows.

9. A wireless telecommunications apparatus according to claim 8, wherein: the first number is one of a plurality predetermined numbers; and the circuitry is configured to attempt to soft-combine ephemeris information in a number of consecutive SI windows of the plurality of SI windows corresponding to each of the plurality of predetermined numbers until the soft-combining is successful.

10. A wireless telecommunications apparatus according to claim 1 , wherein the number of SI windows in the subset of the plurality of SI windows is the same for a plurality of different satellites.

11. A wireless telecommunications apparatus according to claim 1 , wherein the number of SI windows in the subset of the plurality of SI windows is different for a plurality of different satellites and is indicated, for each of the satellites, in a system information block, SIB, carrying the ephemeris information.

14. A wireless telecommunications apparatus according to claim 13, wherein the circuitry is configured to transmit a signal indicating the subset of the plurality of SI windows.

15. A wireless telecommunications apparatus according to claim 14, wherein the signal is a system information block 1 , SIB1 , signal.

16. A wireless telecommunications apparatus according to claim 14, wherein the signal is a downlink control information, DCI, signal carried on a physical downlink control channel, PDCCH.

17. A wireless telecommunications apparatus according to claim 13, wherein the circuitry is configured to determine the subset of the plurality of SI windows based on a measured quality and/or strength of signals received from the network by another wireless telecommunications apparatus.

18. A wireless telecommunications apparatus according to claim 13, wherein the subset of the plurality of SI windows is preconfigured.

19. A wireless telecommunications apparatus according to claim 13, wherein the number of SI windows in the subset of the plurality of SI windows is the same for a plurality of different satellites.

20. A wireless telecommunications apparatus according to claim 13, wherein the number of SI windows in the subset of the plurality of SI windows is different for a plurality of different satellites and is indicated, for each of the satellites, in a system information block, SIB, carrying the ephemeris information.

26. A program for controlling a computer to perform a method according to any one of claims 22 to 25.

27. A storage medium storing a program according to claim 26.