WO2024179584A1

WO2024179584A1 - Non-terrestrial network communication method, user equipment, and radio node

Info

Publication number: WO2024179584A1
Application number: PCT/CN2024/079676
Authority: WO
Inventors: Yi-Ting Lin
Original assignee: Purplevine Innovation Co Ltd
Current assignee: Purplevine Innovation Co Ltd
Priority date: 2023-03-02
Filing date: 2024-03-01
Publication date: 2024-09-06
Anticipated expiration: 2025-09-02
Also published as: CN120787442A

Abstract

A non-terrestrial network (NTN) communication method is disclosed. A network node broadcasts a first system information block (SIB), wherein the first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by a first satellite, and the reference location of the earth-moving cell is for location-based measurement initiation for terrestrial network (TN) neighbor cell measurement. The first SIB also includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is for location-based measurement initiation for TN neighbor cell measurement.

Description

NON-TERRESTRIAL NETWORK COMMUNICATION METHOD, USER EQUIPMENT, AND RADIO NODE

BACKGROUND OF DISCLOSURE

1. Field of Disclosure

The present disclosure relates to the field of communication systems, and more particularly, to a Non-Terrestrial Network (NTN) communication method, user equipment (UE) , and radio node.

2. Description of Related Art

A 3GPP Rel-17 study item has investigated how to enable New Radio (NR) and next generation radio access network (NG-RAN) for Non-Terrestrial Networks (NTN) . The study includes transparent payload based Geostationary Orbit (GSO) and Non-Geostationary Orbit (NGSO) network scenarios addressing 3GPP user equipment (UE) that can access Global Navigation Satellite System (GNSS) in both earth fixed and/or earth moving cell configurations. A 3GPP Rel-18 work item (WI) on NR NTN enhancements (NR_NTN_enh) has been approved to define enhancements for NG-RAN based NTN. The enhancements for NG-RAN based NTN includes mobility and service continuity enhancements by addressing challenges of NTN such as large propagation delay and satellite motion.

According to the outcome of Rel-17 NR NTN WI, UE can use time-based or location-based cell (re) selection procedure. As shown in FIG. 1, cell A and cell B are quasi-earth fixed cells. For a quasi-earth fixed cell, the cell coverage area covered by the satellite is fixed for a period of time, and all the UEs within the coverage area can be served by the satellite for the same period of time. As specified in Rel-17 NR NTN, the gNB transmits service stop time information. This information, denoted by t-Service, indicates the precise moment when a cell deployed through the NTN quasi-earth fixed system will cease providing service to the currently covered area. In a time-based cell (re) selection procedure, a UE shall perform neighbor cell measurements before the time denoted by t-Service.

Technical Problem

As shown in FIG. 2, cells A, B, and C are earth-moving cells. For an earth-moving cells, the cell coverage area covered by the satellite will dynamically change location as the satellite moves. The service stop time may be different for each UE within the cell coverage area. Due to the potential variability in service stop times for individual UEs within the cell coverage area, the traditional time-based cell (re) selection (i.e., unified t-Service) deemed unsuitable and necessitates enhancements for earth-moving cell.

A crucial challenge associated with the existing coverage information transmission technique lies in optimizing the data format for efficient transmission. The chosen format needs to minimize data volume and maximize spectrum efficiency.

An efficient format of the reference location and distance threshold for estimating the serving cell’s stop time needs to be standardized for estimating the service stop time of an earth-moving cell.

Another key obstacle is guaranteeing uninterrupted service as UE moves between satellite and terrestrial networks (TN) . According to current 3GPP standards and agreements, UE is not required to perform neighbor cell measurements for TN neighbor cells in an area where there is no TN coverage. Therefore, determining the presence of a TN cell in the neighboring area poses a significant challenge.

An optimized format of the virtual areas for estimating the neighbor TN cells needs to be standardized to avoid unnecessary neighbor cell measurements.

SUMMARY

An object of the present disclosure is to propose an NTN communication method.

In a first aspect, an embodiment of the invention provides non-terrestrial network (NTN) communication method for execution by a user equipment (UE) , comprising:

receiving a first system information block (SIB) , wherein the first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by a first satellite, and the reference location of the earth-moving cell is to be used by the UE in location-based measurement initiation for terrestrial network (TN) neighbor cell measurement; or

wherein the first SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is to be used by the UE in location-based measurement initiation for TN neighbor cell measurement.

In a second aspect, an embodiment of the invention provides a user equipment (UE) comprising a processor configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the disclosed method and any combination of embodiments of the disclosed method.

In a third aspect, an embodiment of the invention provides a non-terrestrial network (NTN) communication method for execution by satellite system, comprising:

broadcasting a first system information block (SIB) , wherein the first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by a first satellite, and the reference location of the earth-moving cell is for location-based measurement initiation for terrestrial network (TN) neighbor cell measurement; or

wherein the first SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is for location-based measurement initiation for TN neighbor cell measurement.

In a fourth aspect, an embodiment of the invention provides a base station comprising a processor configured to call and run a computer program stored in a memory, to cause a device in which the processor is installed to execute the disclosed method.

The disclosed method may be programmed as computer executable instructions stored in non-transitory computer readable medium. The non-transitory computer readable medium, when loaded to a computer, directs a processor of the computer to execute the disclosed method.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

The disclosed method may be programmed as a computer program product, that causes a computer to execute the disclosed method.

The disclosed method may be programmed as a computer program, that causes a computer to execute the disclosed method.

Advantageous Effects

Embodiments of the disclosure provide a circular format composed of fan-shaped regions.

The footprint of the satellite is formatted as a circular shape which is segmented into equally divided fan-shaped regions.

Embodiments of the disclosure provide an elliptical format composed of rectangles.

The footprint of the satellite is formatted as an elliptical shape which is segmented into equally divided rectangles.

Embodiments of the disclosure provide procedures of transmitting TN coverage information to a UE.

Embodiment of the disclosure illustrate transmission of TN coverage information to the UE through broadcasting or unicasting, and how the UE performs TN neighbor cell measurements based on the TN coverage information.

An efficient format assisting NTN-TN mobility can reduce transmission overhead from the satellite to the UE, thus enhancing the spectrum efficiency.

BRIEF DESCRIPTION OF DRAWINGS

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field may obtain other figures according to these figures without paying the premise.

FIG. 1 illustrates a schematic view of a quasi-earth fixed cell.

FIG. 2 illustrates a schematic view of a quasi-earth fixed cell.

FIG. 3 illustrates a schematic view of a telecommunication system.

FIG. 4 illustrates a schematic view showing an embodiment of the non-terrestrial network (NTN) communication method.

FIG. 5 illustrates a schematic view showing another embodiment of the non-terrestrial network (NTN) communication method.

FIG. 6 illustrates a schematic view showing another embodiment of the non-terrestrial network (NTN) communication method.

FIG. 7 illustrates a schematic view showing another embodiment of the non-terrestrial network (NTN) communication method.

FIG. 8 illustrates a schematic view showing a circular format for a satellite footprint.

FIG. 9 illustrates a schematic view showing an example of indexing the fan-shaped regions.

FIG. 10 illustrates a schematic view showing another example of indexing the fan-shaped regions.

FIG. 11 illustrates a schematic view showing an elliptical format for the satellite’s footprint.

FIG. 12 illustrates a schematic view showing an example of indexing rectangle regions in the elliptical format for the satellite’s footprint.

FIG. 13 illustrates a schematic view showing another example of indexing rectangle regions in the elliptical format for the satellite’s footprint.

FIG. 14 illustrates a schematic view showing an example of indexing rectangle regions in the elliptical format for the satellite’s footprint rotated by an angle θ.

FIG. 15 illustrates a schematic view showing another example of indexing rectangle regions in the elliptical format for the satellite’s footprint rotated by an angle θ.

FIG. 16 illustrates a schematic view showing a procedure of transmitting TN coverage information.

FIG. 17 illustrates a schematic view showing a UE estimates the time when the satellite’s coverage leaves the UE.

FIG. 18 illustrates a schematic view showing a user equipment (UE) .

FIG. 19 illustrates a schematic view showing a network node.

FIG. 20 illustrates a schematic view showing a chip or executing the disclosed method in a UE.

FIG. 21 illustrates a schematic view showing a chip or executing the disclosed method in a network node.

FIG. 22 illustrates a schematic view showing a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

With reference to FIG. 3, a telecommunication system including a user equipment (UE) 10a, a UE 10b, a base station (BS) 20a, and a network entity device 30 executes the disclosed method according to an embodiment of the present disclosure. FIG. 3 is shown for illustrative not limiting, and the system may comprise more UEs, satellites, BSs, and core network (CN) entities. Connections between devices and device components are shown as lines and arrows in the FIGs.

A satellite wireless system provides a multicast, broadcast and/or a unicast service to a plurality of wireless devices or UEs, such as UE 10a-10g, according to a method of the present disclosure. The UEs, such as UE 10a-10g, are connected to one or more satellite radio access nodes, such as a first on-board satellite radio access node 201 and a second on-board satellite radio access node 202, via first radio interface (Uu) . Each of the first on-board satellite radio access node 201 and a second on-board satellite radio access node 202 comprises a satellite. An on-board satellite radio access node may comprise a base station, such as gNB. Alternatively, a single satellite radio access node may comprise two interconnected nodes through a user plane internal network interface (F1-U) and a first control plane internal network interface (F1-C) . One of these nodes known as a distributed unit (DU) can be deployed on board a satellite, while the other known as a centralized unit (CU) is situated on the ground. A on-ground network 200 may comprise at least one of the CU, a base station 20a, and a base station 20b. At least one of network nodes of the on-ground network 200 (e.g., the satellite radio access nodes and the base stations 20a and 20b) is connected to a user plane function (UPF) 30b via NG-U interface and to an access and mobility management function (AMF) 30c via a second control plane internal network interface NG-C. A session management function (SMF) 30 is connected to AMF 30c through interface N11 and connected to UPF 30b through interface N4. The use plane function is connected to a data network (DN) 40 to provide the respective multicast, broadcast and/or a unicast service to the UEs.

CN 30 may include LTE CN or 5G core (5GC) which includes user plane function (UPF) , session management function (SMF) , mobility management function (AMF) , unified data management (UDM) , policy control function (PCF) , control plane (CP) /user plane (UP) separation (CUPS) , authentication server (AUSF) , network slice selection function (NSSF) , and the network exposure function (NEF) .

An example of the UE in the description may include one of the UEs 10a to 10g. An example of the base station in the description may include one of the base station 20a or 20b. Uplink (UL) transmission of a control signal or data may be a transmission operation from a UE to a base station. Downlink (DL) transmission of a control signal or data may be a transmission operation from a base station to a UE. A DL control signal may comprise a Medium Access Control (MAC) control element (CE) , downlink control information (DCI) or a radio resource control (RRC) signal, from a base station to a UE.

In the description, unless elsewhere specified, an earth-moving cell or a quasi-earth fixed cell means a cell provided by an NTN satellite for serving one or more UEs, such as UE 10a or UE 10b. The earth-moving cell or quasi-earth fixed cell can be referred to as a serving cell of the one or more UEs.

The network (e.g., network entity device 30 or base station 20a) may send TN coverage information to the UEs (e.g., UE 10a and UE 10b) . Options of the TN coverage information are illustrated in the following:

1. The TN coverage information may include cell center and cell radius of TN neighbor cell (s) , or in other words, the reference location and distance threshold of TN neighbor cell (s) .

2. The TN coverage information may include a boundary line between TN area and NTN area.

3. For quasi-earth fixed cells, TN coverage information is described by a distance range from the cell center and an angle range based on a reference direction.

4. System information may be used to include an indication to signify overlap between the coverage of NTN cells and terrestrial TN cells.

5. NTN cell can be divided to several virtual areas based on certain criteria. The virtual areas and the corresponding TN frequency information are broadcast as assistance information to help UE perform more accurate TN measurements.

6. The TN coverage information may include a parameter to describe the coverage area of a TN neighbor cell using the polygon shape captured in TS 23.032.

For options 1, 3, and 6, a TN coverage area is described as a shape within a range (e.g., a circle with a center and a radius or a polygon) . This provides the advantage that the UE can determine whether it is covered within the TN coverage based on its position. However, broadcasting all TN coverage information may be very difficult since one NTN cell may contain tens to hundreds of TN coverage areas. Moreover, broadcasting the information of these TN cells may expose the location of the TN cells and cause security concerns.

Option 2 is more suitable for the TN cells located in a specific terrain, such as TN cells distributed along the coastlines or mountain edges.

Option 4 relies on a simple overlap indicator, but it lacks specific location information. This means the UE might perform unnecessary neighbor cell measurements even when no TN cell is nearby. To address this, Option 5 proposes dividing the entire NTN cell into smaller virtual areas. This reduces the need for extensive measurements, saving power for the UEs, which is also the goal of Option 5.

In the present invention, the format of the reference location and distance threshold for estimating the serving cell’s stop time and the format of the virtual areas divided from the NTN cell are provided to optimize the transmitted bits from the satellite to the UE, thereby increasing the spectrum efficiency.

With reference to FIG. 4, an embodiment of the non-terrestrial network (NTN) communication method is detailed in the following. The first satellite 201 is the first on-board satellite radio access node.

Step S001: The first satellite broadcasts a first system information block (SIB) to one or more UEs, such the UE 10a-10g. For simplicity, only UE 10a is shown in the FIG. 4 to represent the one or more UEs. The first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by the first satellite, and the reference location of the earth-moving cell is for location-based measurement initiation for terrestrial network (TN) neighbor cell measurement. The UE 10 receives the SIB. The reference location of the earth-moving cell is to be used by the UE in location-based measurement initiation for terrestrial network (TN) neighbor cell measurement. The UE 10a may receive TN coverage information in another SIB or a unicast message. Alternatively, the UE 10a may receive TN coverage information in the same first SIB.

Step S002: The UE 10a performs TN neighbor cell measurement based on TN coverage information and information in the first SIB.

With reference to FIG. 5, another embodiment of the non-terrestrial network (NTN) communication method is detailed in the following. The second satellite 202 is the second on-board satellite radio access node.

Step S011: The second satellite 202 broadcasts a second SIB to one or more UEs, such the UE 10a-10g. For simplicity, only UE 10a is shown in the FIG. 5 to represent the one or more UEs. The second SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is for location-based measurement initiation for TN neighbor cell measurement. The UE 10a receives a second SIB. the reference location of the quasi-earth fixed cell is to be used by the UE in location-based measurement initiation for TN neighbor cell measurement. The UE 10a may receive TN coverage information in another SIB or a unicast message. Alternatively, the UE 10a may receive TN coverage information in the same second SIB.

Step S012: The UE 10a performs TN neighbor cell measurement based on TN coverage information and information in the second SIB.

With reference to FIG. 6, another embodiment of the non-terrestrial network (NTN) communication method is detailed in the following. A satellite system 200 comprises at least one or both of the first satellite 201 and the second satellite 202.

Step S021: The satellite system 200 broadcasts the first SIB and the second SIB to one or more UEs, such the UE 10a-10g. For simplicity, only UE 10a is shown in the FIG. 6 to represent the one or more UEs. The UE 10a may receive TN coverage information in another SIB or a unicast message. Alternatively, the UE 10a may receive TN coverage information in the first SIB or the second SIB.

Step S022: The UE 10a performs TN neighbor cell measurement based on TN coverage information and information in the first SIB and the second SIB.

With reference to FIG. 7, another embodiment of the non-terrestrial network (NTN) communication method is detailed in the following. A satellite system 200 comprises at least one or both of the first satellite 201 and the second satellite 202.

Step S021: The satellite system 200 broadcasts the first SIB to one or more UEs, such the UE 10a-10g. For simplicity, only UE 10a is shown in the FIG. 7 to represent the one or more UEs.

The first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by the first satellite, and the reference location of the earth-moving cell is for location-based measurement initiation for terrestrial network (TN) neighbor cell measurement. The UE 10 receives the first SIB. The reference location of the earth-moving cell is to be used by the UE in location-based measurement initiation for terrestrial network (TN) neighbor cell measurement.

The first SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is for location-based measurement initiation for TN neighbor cell measurement. The UE 10a receives the first SIB. the reference location of the quasi-earth fixed cell is to be used by the UE in location-based measurement initiation for TN neighbor cell measurement.

The UE 10a may receive TN coverage information in another SIB or a unicast message. Alternatively, the UE 10a may receive TN coverage information in the same first SIB.

Step S022: The UE 10a performs TN neighbor cell measurement based on TN coverage information and information in the first SIB.

In some embodiments of the disclosure, the reference location indicated by the first parameter is a geographical position of a center of a cell of the first satellite providing the earth-moving cell.

In some embodiments of the disclosure, the reference location indicated by the second parameter is a geographical position of a center of a cell of the second satellite providing the quasi-earth fixed cell.

In some embodiments of the disclosure, TN coverage information comprises a time parameter that indicates a time associated with the geographical position of the cell center of the first satellite.

In some embodiments of the disclosure, an NTN serving cell comprising the earth-moving cell or the quasi-earth fixed cell includes virtual areas. A second SIB conveys the virtual areas and the corresponding TN frequency information. The UE receives the second SIB that conveys the virtual areas and the corresponding TN frequency information.

In some embodiments of the disclosure, the second SIB comprise at least one frequency and/or at least one index of the virtual areas associated with at least one TN neighbor cell. The frequency and/or the index are transmitted along with TN coverage information. The UE receives the frequency and/or the index along with TN coverage information. The UE receives from the second SIB at least one frequency and/or at least one index of the virtual areas associated with at least one TN neighbor cell. The UE receives the frequency and/or the index along with TN coverage information.

In some embodiments of the disclosure, the satellite system further broadcasts TN coverage information, and the UE receives the TN coverage information. TN coverage information comprises a cell center and a cell radius of at least one TN neighbor cell of a user equipment (UE) .

In some embodiments of the disclosure, the satellite system further broadcasts TN coverage information, and the UE receives the TN coverage information. TN coverage information comprises a radius of a cell of a first satellite providing an earth-moving cell.

In some embodiments of the disclosure, the satellite system further broadcasts TN coverage information, and the UE receives the TN coverage information. TN coverage information comprises a radius of a cell of a second satellite providing a quasi-earth fixed cell.

In some embodiments of the disclosure, the satellite system comprises one or more NTN satellite.

1. A circular format composed of fan-shaped regions

As shown in FIG. 8, when a satellite's transmission beam is directed perpendicular to the Earth's surface, a footprint of the satellite on the ground becomes nearly circular. This is due to the uniform distribution of the signal across the beam at this specific angle. When the satellite’s coverage is a quasi-earth fixed cell, a center of the footprint can serve as the reference location, which is given by the parameter referenceLocation-r17 in the SIB19 system information. The radius of the footprint (denoted by R) depends on the height of the satellite (i.e., the distance of the satellite from the Earth’s surface) and an allowed elevation angle, given by the parameter distanceThresh-r17 in the SIB19 system information. When the satellite provides an earth-moving cell, the center of the footprint may be given by referenceLocation-r17 at a specific time. The specific time may be given by the parameter epochTime of the serving satellite. If the epochTime of the serving satellite is not available, an example of the specific time may be the end of a System Information (SI) window where the SIB19 is scheduled. In an alternative way, the center of the footprint may be derived from position and velocity (PV) information of ephemeris information in SIB19 system information.

The footprint can be segmented into equally divided fan-shaped regions. For example, as shown in FIG. 9, the footprint is segmented into 8 equally divided fan-shaped regions, each with an angle of 45 degrees. The fan-shaped regions are indexed by 0, 1, 2, 3, 4, 5, 6, and 7. All the fan-shaped regions can be indexed by a bitmap where the most significant bit (MSB) in the bitmap indicates the fan-shaped region with the first index and the least significant bit (LSB) in the bitmap indicates the fan-shaped region with the last index. For example, the pie regions in FIG. 9 can be indexed by an 8-bit bitmap. The fan-shaped regions may be indexed according to various rules. For example, in one of the indexing rules, the fan-shaped region with the first index (e.g., 0) spanning θ degrees (e.g., 45 degrees) is defined by indexing clockwise from a zero degree on the positive Y-axis. Subsequent fan-shaped regions follow, with their indexes increasing by θ degrees (e.g., 45 degrees) each. The indexing rule may be explicitly or implicitly shared by the gNB and the UE (e.g., UE 10a) so that the gNB (e.g., the first satellite 201, the second satellite 202, the base station 20a, and/or the base station 20b) can use the bitmap to indicate the fan-shaped regions. In the bitmap, each bit is used to index and represent one corresponding fan-shaped region and stores one binary digit, either 0 or 1, to indicate whether there is any TN cell in the fan-shaped region of the index. For example, if a bit is set to 1, it means at least one TN cell exists within that region. Otherwise, if the bit is 0, there are no TN cells available. For example, a bitmap of 11000001 indicates that there is at least one TN cell in the fan-shaped regions with indices 0, 1, and 7. Since the bitmap is fixed for a quasi-earth fixed cell, it may be transmitted from the gNB to all the UEs by a broadcast signal (e.g., system information) . For an earth-moving cell, the bitmap is changed with time, and the gNB (e.g., the first satellite 201, the second satellite 202, the base station 20a, and/or the base station 20b) may update the bitmap frequently to guarantee the latest bitmap of the satellite’s coverage can be signaled to the UE. While frequent updates ensure UEs receive the latest coverage information, excessive updates create bandwidth overhead and are therefore undesirable. To minimize the need for frequent updates or transmissions, the gNB may transmit the bitmap at longer intervals, and the UE derives the latest bitmap by extrapolation using the reference location and the epoch time. Alternatively, instead of waiting for regular broadcasts, the UE can also ask for the coverage information directly from the satellite. For example, the bitmap can also be transmitted to the UE through unicast signaling (e.g., dedicated RRC configuration) upon the UE’s request for the bitmap. Based on the information of reference location, epoch time, the UE’s position (e.g., by global positioning system, GPS) , and the indexing rule, the UE first determines a fan-shaped region in which the UE is located. Based on the bitmap received from the gNB, the UE can then determine whether there are any TN cells in the determined fan-shaped region (referred to as a located region, a current region, or simply its region) . If at least one TN cell is in its located region, the UE may initiate neighbor cell measurements before the moving-cell’s coverage leaves the UE. That is, UE can perform location-based measurement initiation for neighbor cell measurements when being served in a quasi-earth fixed cell and/or earth-moving cell. The location-based measurement initiation is included in and as a portion of a location-based cell (re) selection procedure. For example, the UE (e.g., UE 10a) may initiate neighbor cell measurements based on a reference location of a serving cell provided by an NTN satellite. The serving cell may comprise a quasi-earth fixed cell and/or earth-moving cell. The reference location of the serving cell may comprise a geographical position of a center of a footprint of a first satellite providing an earth-moving cell or a geographical position of a center of a footprint of a second satellite providing a quasi-earth fixed cell.

Since the radius of the footprint can be hundreds of kilometers, UEs within the same fan-shaped region but occupying different positions may experience disparate situations. For example, one UE (e.g., UE 10a) is located at the center of the footprint, and another UE is located at the edge of the footprint. Assuming that the TN cell (s) is located near the center of the footprint, the UE (e.g., UE 10d) at the edge of the footprint may expend unnecessary power attempting to measure the TN cell, but eventually cannot find the TN cell (s) . In order to improve the efficiency of neighbor cell measurements, the footprint can be further divided into more small regions.

With reference to FIG. 10, in an example, the footprint is divided into two parts, one is a circle with small radius (i.e., r<R) and the other is an annulus. The fan-shaped regions in the circle are indexed by 0, 1, 2, 3, 4, 5, 6, and 7. The annulus forms a ring around the circle. The fan-shaped regions of the annulus are indexed by 8, 9, 10, 11, 12, 13, 14, and 15. The example is not intended to limit the disclosure. Note that the indexing for the fan-shaped regions can commence either from the circle and progress towards the annulus or vice versa. Note that the footprint can be divided into more than one annulus if higher precision is required.

Therefore, for a circular format composed of fan-shaped regions, the necessary assistance information for a UE (e.g., UE 10a) to determine whether there is at least one TN cell nearby may include the reference location, the radius of the footprint, the angle used to segment the footprint (e.g., 5, 10, 15, …, 90 degrees, etc. ) , the bitmap with time information for indexing the fan-shaped regions at a specific time, the radius of the small circle, and the width of the annulus (es) .

Note that the radius of the small circle and the width of the annuluses may be represented by a value which is used to divide the radius of the footprint. For example, value 2 is used to divides the radius of the footprint into halves (i.e., the radius of the small circle is half of the radius of the footprint, and the width of the annulus is half of the radius of the footprint) and value 3 is used to divides the radius of the footprint into thirds (i.e., the radius of the small circle is one third of the radius of the footprint, the width of the first annulus is one third of the radius of the footprint, and the width of the second annulus is also one third of the radius of the footprint) . Given that the reference location, footprint radius, and time information are already included in existing messages pr message formats, the extra bits primarily encompass those required for the bitmap (e.g., 8, 16, 32 bits, etc. ) and the value used for dividing the radius of the footprint. This results in a significantly lower bit count compared to providing the positions of TN cells.

2. An elliptical format composed of rectangle regions

Earth’s rotation causes a specific region on the Earth’s surface to undergo changes in its position relative to the satellite’s orbital path. In order to continually provide coverage for a specific region, the satellite may have the capability of adjusting the direction of the transmission beam. As shown in FIG. 11, when the satellite’s transmission beam is not perpendicular to the Earth’s surface, the satellite’s footprint appears as an ellipse. The reference location is the center of the ellipse, and can be derived from the ephemeris information and the elevation angle at the reference location. The major and minor axes of the ellipse (denoted as a and b) depend on the height of the satellite (i.e., the distance of the satellite from the Earth’s surface) and the allowed elevation angle.

In this embodiment, the footprint is segmented into equally divided rectangle regions. For example, as shown in FIG. 12, the footprint is segmented into 4 equally divided rectangles that are indexed by 0 to 3. Each rectangle has a long side equivalent to the major axis and a short side equivalent to the minor axis of the ellipse. The rectangles can be indexed by a bitmap where MSB in the bitmap indicates the rectangle with the first index and LSB in the bitmap indicates the rectangle with the last index. For example, the rectangles in FIG. 12 can be indexed by a 4-bit bitmap. The indexing for the rectangles may be performed based on various rules. For example, in one of the rules, indexing commences from the upper-leftmost and moves to low-rightmost, where a rectangle with the first index (e.g., 0) is the top left region, the rectangle with the highest index is the bottom right region. The indexing rule may be explicitly or implicitly shared by the gNB and the UE (e.g., UE 10a) so that the gNB can use the bitmap to indicate the rectangles.

With reference to FIG. 13, the footprint is segmented into 16 equally divided rectangles that are indexed by 0 to 15. The indexing rule in FIG. 13 is the same as the rule in FIG. 12. The advantage of this method is that the gNB only needs to transmit a value (denoted as r) for equally dividing the rectangles. For example, when the value r=1, the UE (e.g., UE 10a) can determine the coordinates of the four vertices of the rectangle with index 0 as (X₀-b, Y₀+a) , (X₀, Y₀+a) , (X₀-b, Y₀) , and (X₀, Y₀) , and so on for other indexed rectangles.

In order to improve the efficiency of neighbor cell measurements, the ellipse can be further divided into more small rectangles. In FIG. 13, each rectangle in FIG. 12 may be further segmented into 4 equally divided rectangles such that the rectangles in FIG. 13 are indexed by a 16-bit bitmap. In this case, taking the value r=0.5, and the UE (e.g., UE 10a) can determine the coordinates of the four vertices of the rectangle with index 0 as (X₀-b, Y₀+a) , (X₀-0.5b, Y₀+a) , (X₀-b, Y₀+0.5a) , and (X₀-0.5b, Y₀+0.5a) , and so on for other indexed rectangles. Based on the coordinates of the four vertices and the position calculated by the positioning system (e.g., GPS) , the UE can determine a rectangle in which the UE is located.

Sometimes the satellite's orbit is not parallel to the longitude, and the coordinates of the vertices will be rotated by an angle=θ, where the angle is the angle between the orbit and the longitude. In FIG. 14 and FIG. 15, an example is provided taking the value r=1, and the coordinates of the four vertices of the rectangle with index 0 as (X₀-b·cosθ+a·sinθ, Y₀+b·sinθ+a·cosθ) , (X₀+a·sinθ, Y₀+a·cosθ) , (X₀-b·cosθ, Y₀+b·sinθ) , and (X₀, Y₀) . After performing inverse rotation for its position and the four vertices of the rectangle with angle=θ back to Cartesian coordinates, the UE (e.g., UE 10a) can determine in which rectangle the UE is located.

3. The procedures of transmitting TN coverage information to a UE

With reference to FIG. 16, a procedure of transmitting TN coverage information to the UE (e.g., UE 10a) is detailed in the following. The procedure comprises configuring TN coverage information by broadcasting (i.e., step 0) and unicasting (i.e., steps 2-4) . Note that the broadcasting and unicasting can operate independently or in conjunction with each other.

Step 0: The NTN gNB (e.g., the first satellite 201, the second satellite 202, the base station 20a, and/or the base station 20b) broadcasts its TN coverage information through the satellite. Table 1 shows an example of the format of the TN coverage information. TN coverage information for earth-moving cell or quasi-earth fixed cell is illustrated in the following.

For an earth-moving cell provided by a satellite, the parameter referenceLocation-r18 indicates the geographical position of the center of the footprint of the satellite and may reuse the format of Rel-17 reference location.

For a quasi-earth fixed cell provided by a satellite, the geographical position of the center of the footprint of the satellite may be conveyed in the parameter referenceLocation-r17 in the system information of SIB19.

For an earth-moving cell, the epochTime-r18 indicates the epoch time when the satellite transmits the beam to Earth’s surface with the geographical position of the center of the footprint indicated by the referenceLocation-r18. The sfn and subFrameNR refers to the system frame number (SFN) and sub-frame of the serving cell. For a quasi-earth fixed cell, the epochTime-r18 can be omitted because the center of the footprint will not change over time.

The radius-r18 indicates the radius of the footprint of the satellite when the satellite’s transmission beam is perpendicular to the Earth’s surface.

The semimajor-r18 and the semiMinor-r18 indicates the semi-major axis and semi-minor axis respectively of the footprint when the satellite’s transmission beam is not perpendicular to the Earth’s surface. Note that only one of radius-r18 and semimajor-r18/semiMinor-r18 will be presented.

The angleOfFanShaped-r18 indicates the angle of the fan-shaped regions that is segmented from the footprint, with each region spanning every degree indicated by the angleOfFanShaped-r18.

The widthOfAnnuals-r18 indicates the width of the annual. The width of the annual may be shown as a ratio of the radius. For example, when widthOfAnnuals-r18=1/2, the footprint is divided into a small circle with radius equal to half of the radius of the footprint and one annulus with width equal to half of the radius of the footprint. When widthOfAnnuals-r18=1/3, the footprint is divided into a small circle with radius equal to one third of the radius of the footprint, one annulus with width equal to one third of the radius of the footprint, and the other one annulus with width equal to one third of the radius of the footprint.

The dividingFactorForRectangle-r18 indicates the value for equally dividing the long and short sides of the rectangle where the long side is equal to the major axis of the footprint (i.e., 2*semiMajor) and the short side is equal to the minor axis of the footprint (i.e., 2*semiMinor) .

The rotatedAngleOfRectangle-r18 indicates the rotated angle between the satellite’s orbit and the longitude. For example, when rotatedAngleOfRectangle-r18=0°, the satellite moves toward the north. When rotatedAngleOfRectangle-r18=90°, the satellite moves toward the east, and so on.

The TNCoverageBitmap-r18 indicates whether there are any TN cells in each of the indexed region. For example, a bitmap of 11000001 indicates that there is at least one TN cell in the regions with indices 0, 1, and 7. The number of bits is equal to (360/angleOfFanShaped-r18 /widthOfAnnulus-r18) or (2*1 /dividingFactorForRectangle-r18) ².

Table 1 TN coverage information

Step 1: Based on the received TN coverage information, the UE (e.g., UE 10a) first determines a region in which the UE is located and an index of the region, and determines whether any TN cell is in its located region.

Step 2: In case the gNB (e.g., the first satellite 201, the second satellite 202, the base station 20a, and/or the base station 20b) does not broadcast (all necessary) TN coverage information, the UE may send a Registration/ATTACH Request message to the serving AMF (e.g., for an initial access, periodic registration or registration update) and includes a request for provision of TN coverage information. The request message serves as UE subscription to request TN coverage information. Additional parameters can be included in the Request message to indicate UE’s geographical position, time, and satellite ID, etc. The time may comprise time information (e.g., Coordinated Universal Time (UTC) received from the GNSS or timestamp of system frame and subframe number) when the UE is located at the geographical position.

Step 3: The serving AMF may verify the UE subscription to ensure the UE is eligible for TN coverage information and determine whether the geographical position can be supported (e.g., in a country supported by the AMF) .

Step 4: When the serving AMF determines the UE is eligible for TN coverage information, the AMF responds to the request by sending the TN coverage information in the Registration/ATTACH Accept message to the UE. The UE receives TN coverage information. The TN coverage information may include cell center and cell radius of TN neighbor cells of the UE which are not suitable for transmission in broadcast messages. The AMF may request the TN coverage information (e.g., cell center and cell radius of TN neighbor cells of the UE) from another TN’s server (e.g., AMF or Unified Data Management (UDM) of the TN) and send the TN coverage information to the UE at step 4. For example, the TN coverage information may be conveyed in an SIB or a unicast message to the UE.

Step 5: The UE performs neighbor cell measurements for the TN neighbor cells if the TN neighbor cells are located at the same regions where the UE is located. The UE may perform neighbor cell measurements before the satellite’s coverage leaves the UE. To facilitate rapid measurement of TN neighbor cell (s) by the UE, the frequency of the TN cell and the corresponding TN identifier (e.g., TN cell ID (s) or indices of the small regions, etc. ) can be transmitted to the UE along with the TN coverage information.

As shown in FIG. 17, the UE can estimate the time (i.e., T₂) that the satellite’s coverage leaves the UE based on velocity of the satellite and the reference location at epoch time T₀. The velocity of the satellite may be transmitted to the UE in the ephemeris information of SIB19 system information. If the velocity is not available in the ephemeris information, the UE can estimate the reference location (X₂, Y₂) by extrapolating from reference location (X₀, Y₀) and reference location (X₁, Y₁) .

With reference to FIG. 18, the UE 10 may include a processor 11a, a memory 12a, and a transceiver 13a. The processor 11a is configured to call and run a computer program stored in the memory 12a, to cause UE 10 in which the processor 11 is installed to execute the disclosed method, steps, and/or functions of a UE. The UE 10 is an example of the UE in the description (e.g., UE 10a to UE 10g) . The transceiver 13a may include baseband circuitry and radio frequency (RF) circuitry.

With reference to FIG. 19, the network node 20 is a network device and may include a processor 21a, a memory 22a, and a transceiver 23a. The processor 21a is configured to call and run a computer program stored in the memory 22a, to cause network node 20 in which the processor 11 is installed to execute the method, steps, and/or functions of a network node. The network node 20 is an example of a satellite, CN network entity, network node, radio node, the base station, or gNB in the description. The transceiver 23a may include baseband circuitry and radio frequency (RF) circuitry.

With reference to FIG. 20, the embodiment of the disclosure also provides a chip 70 that may correspond to a UE in the embodiments of the disclosure. The chip 70 may implement a corresponding process realized by the UE in various methods of the embodiments of the disclosure. The chip 70 includes a processor 71, and the processor 71 may call and run a computer program from memory to implement the methods in the embodiments of the present application.

Optionally, the chip 70 may also include a memory 72. In particular, the processor 71 may call and run the computer program from the memory 72 to implement the methods in the embodiments of the present application.

Moreover, the memory 72 may be a separate device from the processor 71 or may be integrated into the processor 71.

Optionally, the chip 70 may further include an input interface 73. Note that the processor 71 may control the input interface 73 to communicate with other devices or chips, specifically, to obtain messages or data sent by other devices or chips.

Optionally, the chip 70 may further include an output interface 74. Note that the processor 71 may control the output interface 74 to communicate with other devices or chips, specifically, to output messages or data to other devices or chips.

With reference to FIG. 21, the embodiment of the disclosure also provides another chip 80 that may correspond to a network device (e.g., CN network entity, network node, radio node, the base station, or gNB) in the description, and the chip 80 may implement the corresponding processes implemented by the network device in the various methods of the embodiments of the disclosure. The chip 80 includes a processor 81, and the processor 81 may call and run a computer program from the memory 82 to implement the methods in the embodiments of the present application.

Optionally, the chip 80 may further include a memory 82. In particular, the processor 81 may call and run the computer program from the memory 82 to implement the methods in the embodiments of the present application.

Wherein the memory 82 may be a separate device from the processor 81 or may be integrated into the processor 81.

Optionally, the chip 80 may also include an input interface 83. In particular, the processor 81 may control the input interface 83 to communicate with other devices or chips, specifically, to obtain messages or data sent by other devices or chips.

Optionally, the chip may further include an output interface 84. In particular, the processor 81 may control the output interface 84 to communicate with other devices or chips, specifically, to output messages or data to other devices or chips.

FIG. 22 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 22 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, a processing unit 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other as illustrated.

The processing unit 730 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

The baseband circuitry 720 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with 5G NR, LTE, an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the UE, eNB, or gNB (e.g., BS 20a) 20 may be embodied in whole or in part in one or more of the RF circuitries, the baseband circuitry, and/or the processing unit. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC) , an electronic circuit, a processor (shared, dedicated, or group) , and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the processing unit, and/or the memory/storage may be implemented together on a system on a chip (SOC) .

The memory/storage 740 may be used to load and store data and/or instructions, for example, for the system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) ) , and/or non-volatile memory, such as flash memory. In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, the system may have more or less components, and/or different architectures. Where appropriate, the methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

The embodiment of the present disclosure is a combination of techniques/processes that may be adopted in 3GPP specification to create an end product.

A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of the application and design requirement for a technical plan. A person having ordinary skill in the art may use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she may refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

It is understood that the disclosed system, device, and method in the embodiments of the present disclosure may be realized in other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated into another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operates through some ports, devices, or units, whether indirectly or communicative in ways of electrical, mechanical, or other kinds of forms.

The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments may be integrated into one processing unit, physically independent, or integrated into one processing unit with two or more than two units.

If the software function unit is realized and used and sold as a product, it may be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure may be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology may be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server 41, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A non-terrestrial network (NTN) communication method for execution by a user equipment (UE) , comprising:

receiving a first system information block (SIB) , wherein the first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by a first satellite, and the reference location of the earth-moving cell is to be used by the UE in location-based measurement initiation for terrestrial network (TN) neighbor cell measurement; or

wherein the first SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is to be used by the UE in location-based measurement initiation for TN neighbor cell measurement.
The NTN communication method of claim 1, wherein the reference location indicated by the first parameter is a geographical position of a cell center of the first satellite providing the earth-moving cell.
The NTN communication method of claim 1, wherein the reference location indicated by the second parameter is a geographical position of a cell center of the second satellite providing the quasi-earth fixed cell.
The NTN communication method of claim 1, wherein the first SIB comprises a time parameter that indicates a time associated with the geographical position of the cell center of the first satellite.
The NTN communication method of claim 1, wherein an NTN serving cell comprising the earth-moving cell or the quasi-earth fixed cell includes virtual areas;

the UE receives a second SIB that conveys the virtual areas and the corresponding TN frequency information.
The NTN communication method of claim 5, wherein the UE receives from the second SIB at least one frequency and/or at least index of the virtual areas associated with at least one TN neighbor cell, the UE receives the frequency and/or the index along with TN coverage information.
The NTN communication method of claim 1, the UE further receives TN coverage information, wherein the TN coverage information comprises a cell center and a cell radius of at least one TN neighbor cell of the UE.
The NTN communication method of claim 1, the UE further receives TN coverage information, wherein the TN coverage information comprises a radius of a cell a first satellite providing an earth-moving cell.
The NTN communication method of claim 1, the UE further receives TN coverage information, wherein TN coverage information comprises a radius of a cell of a second satellite providing a quasi-earth fixed cell.
A user equipment (UE) comprising:

a processor configured to call and run a computer program stored in a memory, to cause a device in which the processor is installed to execute the method of any of claims 1 to 9.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the method of any of claims 1 to 9.
A computer-readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method of any of claims 1 to 9.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute the method of any of claims 1 to 9.
A computer program, wherein the computer program causes a computer to execute the method of any of claims 1 to 9.
A non-terrestrial network (NTN) communication method for execution by satellite system, comprising:

broadcasting a first system information block (SIB) , wherein the first SIB includes a first parameter that indicates a reference location of an earth-moving cell provided by a first satellite, and the reference location of the earth-moving cell is for location-based measurement initiation for terrestrial network (TN) neighbor cell measurement; or

wherein the first SIB includes a second parameter that indicates a reference location of a quasi-earth fixed cell provided by a second satellite, and the reference location of the quasi-earth fixed cell is for location-based measurement initiation for TN neighbor cell measurement.
The NTN communication method of claim 15, wherein the reference location indicated by the first parameter is a geographical position of a cell center of the first satellite providing the earth-moving cell.
The NTN communication method of claim 15, wherein the reference location indicated by the second parameter is a geographical position of a cell center of the second satellite providing the quasi-earth fixed cell.
The NTN communication method of claim 15, wherein the first SIB comprises a time parameter that indicates a time associated with the geographical position of the cell center of the first satellite.
The NTN communication method of claim 15, wherein an NTN serving cell comprising the earth-moving cell or the quasi-earth fixed cell includes virtual areas;

the satellite further broadcasts a second SIB that conveys the virtual areas and the corresponding TN frequency information.
The NTN communication method of claim 19, wherein the second SIB comprise at least one frequency and/or at least one index of the virtual areas associated with at least one TN neighbor cell, and the frequency and/or the index are transmitted along with TN coverage information.
The NTN communication method of claim 15, the satellite system further broadcasts TN coverage information, wherein the TN coverage information comprises a cell center and a cell radius of at least one TN neighbor cell of a user equipment (UE) .
The NTN communication method of claim 15, the satellite system further broadcasts TN coverage information, wherein the TN coverage information comprises a radius of a cell of a first satellite providing an earth-moving cell.
The NTN communication method of claim 15, the satellite system further broadcasts TN coverage information, wherein the TN coverage information comprises a radius of a cell of a second satellite providing a quasi-earth fixed cell.
The NTN communication method of claim 15, wherein the satellite system comprises one or more NTN satellite.
A network node comprising:

a processor configured to call and run a computer program stored in a memory, to cause a device in which the processor is installed to execute the method of any of claims 15 to 24.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the method of any of claims 15 to 24.
A computer-readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method of any of claims 15 to 24.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute the method of any of claims 15 to 24.
A computer program, wherein the computer program causes a computer to execute the method of any of claims 15 to 24.