WO2020094212A1

WO2020094212A1 - Cell splitting for non-terrestrial networks

Info

Publication number: WO2020094212A1
Application number: PCT/EP2018/080267
Authority: WO
Inventors: Jeroen Wigard; Istvan Zsolt Kovacs
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2018-11-06
Filing date: 2018-11-06
Publication date: 2020-05-14
Anticipated expiration: 2021-05-06

Abstract

According to the present disclosure, a method includes directing a radio beam of a plurality of radio beams toward a coverage area of a non-terrestrial base station; detecting a potential increase in a capacity demand in the coverage area; directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams; detecting a decrease in the capacity demand in the coverage area; and reducing the number of radio beams of the plurality of radio beams directed toward the coverage area. Apparatuses for performing the method, and a computer program product including a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, where computer program code includes code for performing the method are also disclosed.

Description

CELL SPLITTING FOR NON-TERRESTRIAL NETWORKS

TECHNICAL FIELD

This disclosure relates to non-terrestrial networks. More particularly, this disclosure relates to telecommunications networks having base stations deployed in satellites and high-altitude platforms.

BACKGROUND

In the 3^rd Generation Partnership Project (3GPP), a study item, entitled“Study on New Radio (NR) to support non-terrestrial networks, is ongoing. (See 3GPP TR 38.811). The objectives of the study are:

Definition of the“Non-Terrestrial Networks” deployment scenarios and related system parameters, such as architecture, altitude, orbit, and so forth.

Adaptation of the 3GPP channel models for non-terrestrial networks (propagation conditions, mobility,...).

For the deployment scenarios described in 3GPP TR 38.811 , it is important to identify any key impact areas on the New Radio interface that may need further evaluations.

The present disclosure considers geostationary satellites, non-geostationary satellites, and airborne platforms, and covers both the bent-pipe scenario and the case where the base station (gNB) is on board such a satellite or platform. Bent-pipe deployment refers to the process of sending back to Earth what comes in with only amplification and a shift from uplink frequency to downlink frequency. In the present disclosure, these will be collectively referred to as non-terrestrial base stations.

In some of these scenarios, cells for cellular coverage on earth are moving. The speed and changes of the movements of cells depend on the capability of the airborne platform to adjust the antenna beams being used to form a cell, and on the speed and height of the airborne platform, whether geostationary, high-altitude, or low-altitude.

The sizes of cells originating from non-terrestrial base stations depend on the beam footprint size, typical values of which, taken from 3GPP TR 38.811 , are shown in Table 1 below. It is clear that the cell sizes depend on the height of the non-terrestrial base station, including the ability of a base station on an airborne platform to form narrow beams. A beam footprint may also be changed dynamically within certain limits. It is also possible that one satellite or high-altitude platform (HAP) may produce more than one beam. A high- altitude platform station (HAPS) is a moving/flying base station over the intended coverage area at an elevated altitude of approximately twenty kilometers. Geostationary satellites usually orbit at an altitude of 36,000 kilometers above the equator.

Table 1 : Typical beam foot print size

The available satellite frequency bands and spectra for International Telecommunications Union (ITU) Region 1 , which includes Europe, Africa, the former Soviet Union, Mongolia, and the Middle East west of the Persian Gulf, including Iraq, are summarized in Table 2 below. (See R1-1800781). Most of the satellite bands specify frequency-division-duplex (FDD) operation for geostationary (GEO), non-GEO (medium orbit (MEO), low orbit (LEO)), and high-altitude platform system (HAPS). The largest available bandwidths are approximately 2 to 2.5 GHz (Ka, Q, Ku bands), while only 30 MHz to 1.3 GHz are available in the lower-frequency bands (S, L and C bands). For 5G NR communications, it is likely that the S band (~2.lGHz) is the most promising frequency band to be used by both GEO, non-GEO and HAPS, due to its favorable propagation properties; likewise, the C-band (~3.5GHz) is a likely candidate for GEO and non-GEO 5G NR solutions. Typically, frequency reuse is supported, and, therefore, the maximum channel bandwidth per cell (beam) is 1/3 or 1/4 of the spectrum listed in Table 2, where“2x” is meant to indicate that an FDD (DL/UL frequency division multiplexing) band is used. The number of MHz or GHz indicates the available bandwidth. (See 3GPP TR 38.811). Table 2: Typical frequency bands and available satellite bandwidths

(Examples for ITU Region 1)

The use cases for non-terrestrial networks address plane and train connectivity among others. (See 3GPP TR 38.811).

The capacity of a cell typically depends on the amount of spectrum available and the signal-to-interference-and-noise (SINR) conditions. As shown in Table 1 , cell sizes are considerably larger than those of conventional cellular cells. In addition, it is quite likely that non-terrestrial systems are noise-limited due to the large radio paths. In order to have a feasible system, the spectrum should be significantly larger, which is feasible looking at the numbers in Table 2, or the provided capacity per given area should be decreased compared to that of conventional cellular networks. The lower capacity may work quite well in many of the use cases, which can be imagined, such as 5G coverage on the oceans. At the same time, large cells may be beneficial to keep control-plane load, due to handover and the associated delays and gaps, low.

If sufficient spectrum is available, it may be used to create a frequency reuse, such that interference between the different cells or beams is limited, as the different beams will typically have an overlap. However, additional complexity is generated due to the movements of some of the satellites and HAPS, which movements lead to moving cells.

The problem being presently addressed is best expressed as how to deliver the right cell size as a combination of beam footprint and beam spectrum. The right cell size is one which is able to deliver the right amount of capacity, and which keeps the number of mobility events (handovers) as low as possible, while keeping the amount of interference manageable.

In summary, the following principles are well known:

Larger cells lead to fewer mobility events, such as handovers; Frequency reuse leads to less interference; and

Cell splitting can be used to get more capacity; this has heretofore been targeted in a more static manner, that is, through network planning, such as vertical or horizontal high-order sectorization.

It should be understood, both above and in the discussion to follow, that the term“gNB” should be understood to mean“network node”. The term“gNB” is used to denote a network node in 5G. However, it should be understood that the present invention, as described below, is not limited to 5G, but may be applicable to other generations yet to be developed. As a consequence,“gNB” should be understood more broadly as a network node.

SUMMARY

In a first aspect of the present invention, a method comprises: directing a radio beam of a plurality of radio beams toward a coverage area of a non-terrestrial base station; detecting a potential increase in a capacity demand in the coverage area; directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams; detecting a decrease in the capacity demand in the coverage area; and reducing the number of radio beams of the plurality of radio beams directed toward the coverage area.

In a second aspect of the present invention, an apparatus comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following: direct a radio beam of a plurality of radio beams toward a coverage area of a non-terrestrial base station; detect a potential increase in a capacity demand in the coverage area; direct one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams; detect a decrease in the capacity demand in the coverage area; and reduce the number of radio beams of the plurality of radio beams directed toward the coverage area.

In a third aspect of the present invention, an apparatus comprises means for directing a radio beam of a plurality of radio beams toward a coverage area of a non- terrestrial base station; means for detecting a potential increase in a capacity demand in the coverage area; means for directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams; means for detecting a decrease in the capacity demand in the coverage area; and means for reducing the number of radio beams of the plurality of radio beams directed toward the coverage area.

In a fourth aspect of the present invention, a computer program product comprises a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: directing a radio beam of a plurality of radio beams toward a coverage area of a non-terrestrial base station; detecting a potential increase in a capacity demand in the coverage area; directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams; detecting a decrease in the capacity demand in the coverage area; and reducing the number of radio beams of the plurality of radio beams directed toward the coverage area.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of these teachings are made more evident in the following detailed description, when read in conjunction with the attached drawing figures.

Figure 1 illustrates a first scenario where a temporary high-capacity demand, such as a high-speed train, enters the coverage area of three satellites.

Figure 2 illustrates a second scenario where a temporary high-capacity demand enters the coverage area of three satellites.

Figure 3 shows an embodiment of the present invention in which a combined wide beam and a high-capacity beam may be configured by a satellite.

Figure 4 shows a possible implementation of signaling between satellites to coordinate frequency reuse.

Figure 5 shows a simplified block diagram of certain apparatus according to various exemplary embodiments of the present invention. Figure 6 shows an exemplary radio network in which the present invention may find use.

Figure 7 is a flow chart illustrating a method performed by a non-terrestrial base station in accordance with the present disclosure.

DETAILED DESCRIPTION

In summary, as a 5G NR-capable satellite or HAP is assumed to be able to change its number of beams dynamically, the following two triggers are proposed to be used to optimize a system dynamically.

Firstly, when the capacity in a cell is too small, or is anticipated to be too small, through the movement of satellites or HAPs and/or user equipments, the number of beams from the satellites or HAPs, covering the same area, is increased. The cells may start frequency reuse and use narrower beams with higher signal gain. Similarly, when it is detected that the capacity is sufficient, cell splitting is undone and a bigger cell is generated to replace many smaller cells.

Secondly, when interference is found to be a problem in a cell, or when it is anticipated to be a problem through the movement of satellites or HAPs and/or user equipments, cell splitting and frequency reuse is applied across the interfering cells to lower inter-satellite interference and even cellular-satellite system interference.

By frequency reuse is meant the process of using the same radio frequencies on radio transmitter sites within a geographic area that are separated by sufficient distance to cause minimal interference with one another.

Figures 1 and 2 illustrate scenarios where a temporary high-capacity demand, such as a high-speed train, enters the coverage area of three satellites. It is assumed that the satellites are able to form beams and to configure a frequency reuse pattern among their own beams; furthermore, with the availability of inter-satellite communications, the three satellites can also coordinate their frequency reuse pattern to further minimize interference at the borders of their coverage areas.

Referring first to Figure 1 , a high-speed train 110 is shown entering a region covered by the footprints of three satellites or HAPS: SAT 1 footprint 1 12, SAT 2 footprint 114, and SAT 3 footprint 116. Each of the satellites generates radio beams having frequencies fi, f₂, f₃, and f₄. Before high-speed train 1 10 enters the region covered by the three footprints 1 12, 114, 1 16, each satellite generates only one beam covering the entire area of its respective footprint 112, 1 14, 116 using all available bands (fi + f₂ + f₃ + f₄). In other words, the footprints 112, 114, 1 16 reuse the same available spectrum (fi + f₂ + f₃ + f₄). The high-speed train 1 10, travelling along path or track 1 18, first enters the coverage area (footprint) of SAT 3, footprint 1 16, where it will require high radio capacity. Later, the high speed train 110 will require the same, when it passes into the SAT 2 footprint 1 14.

Turning now to Figure 2, once the high-speed train 210 has entered SAT 3 footprint 216, up to four beams per satellite can be formed to cover separate regions of SAT footprint 216. This is referred to as cell splitting. The different carrier frequencies fi, f₂, f₃, f₄ can be allocated to individual beams to achieve the separate coverage. The high-speed train 210 requires high radio capacity. The high-capacity demand is estimated to be possibly served with a narrower beam and by using a lower bandwidth on the fi carrier. Frequency reuse is dynamically generated to offer maximum capacity along the path of the high-speed train 210 across SAT footprint 216 and SAT 2 footprint 214.

Figure 2 shows the resulting reuse pattern. Because the movement of the satellites along their orbits can be determined, and because the satellite system may know the trajectory of the high-speed train 210, SAT 2 and SAT 3 may coordinate with one another and, when required, dynamically form beams using a reuse scheme of the type shown in Figure 2. The narrower beams shown provide a better signal-to -noise ratio (SNR) in their coverage area, and, thus, higher capacity. The drawback of this configuration is that the number of potential handovers between different beams is increased.

Figure 3 shows another embodiment of the present invention in which embodiment a combined wide beam and a high-capacity beam may be configured by a satellite. The high-speed train 310 enters the coverage area of SAT 3, that is, SAT 3 footprint 316, and requires high radio capacity. The narrow beam using fi is dynamically generated to offer maximum capacity along the train path or track 318 across SAT 3 footprint 316, while a combined wide beam uses the remaining available spectrum (f₂ + f₃ + f₄). In other words, the satellite may configure a narrow beam within the coverage area of a larger beam, as shown in Figure 3. SAT 3 could then dynamically steer the beam (fi) to follow the movement of the high-speed train 310. In yet another embodiment, the cell-splitting trigger may be used to provide separate beams for DL (satellite -to-UE) and UL (UE-to-satellite), depending on the traffic load and interference conditions. For example, the reuse pattern example in Figure 2 could be applied for DL, while in FTL the wide -beam of Figure 1 is used.

Triggers, as mentioned above, may be based on interference or capacity. The latter can be easily detected by a non-terrestrial base station by monitoring the resource usage of its own and neighboring cells, whereas interference can be detected by monitoring the performance of connections with user equipments and checking FTE measurements.

In the case of cell splitting, the frequency reuse in the footprint of one satellite must be coordinated with that of neighboring footprints to avoid interference between neighboring cells belonging to different satellites. An example of this is provided in Figure 2. One possible procedure for doing so can be seen in Figure 4, which shows a possible implementation of signaling between satellites to coordinate frequency reuse. It should be noted that the signaling between the satellites can be direct through existing, prior-art inter satellite communications, or routed through one or several terrestrial base stations (gNBs) through the use of a bent-pipe deployment (see 3GPP TR 38.81 1). A potential different implementation would be accomplished by having the satellites implement gNB functionalities (see 3GPP TR 38.811), and then the inter-gNB coordination would be implemented either directly via the inter-satellite links or relayed via the ground gateway(s) on the feeder link to each satellite.

With more particular reference to Figure 4, when cell splitting is triggered for capacity or interference reasons in a cell under the control of a source satellite 402 (or non terrestrial base station), the source satellite 402 (non-terrestrial base station) signals a proposal to a target (neighboring) satellite 404 (non-terrestrial base station) handling a cell bordering that under the control of source satellite 402 on how to split frequency space at the cell border area and overlapping areas of their respective footprints (signal 406). The target satellite 404 sends either an acknowledgment (ACK) or a counterproposal to the source satellite 402 in signal 408. The source satellite 402 then sends either an acknowledgement (ACK) or a negative acknowledgment (NACK) to the target satellite 404 in response to the counterproposal, if one has been made, in signal 410. In either case, once there has been an acknowledgment, the source satellite 402 and the target satellite 404 start the cell splitting procedure.

When the coordination signaling directly between the satellites cannot be achieved, then the mechanism in Figure 4 has to account for the potentially large delays in the transmission/reception of each message because of the feeder link to the ground stations or terrestrial gNBs. One way to achieve this is to use time window validity/applicability information of the actual messages, as disclosed in International Application No. PCT/FI2018/050153, the teachings of which are incorporated herein by reference.

Reference is now made to Figure 5 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing an exemplary embodiment of the present invention. In Figure 5, a wireless network 501 is adapted for communication over a wireless link 51 1 with an apparatus, such as a mobile communication device, which is referred to as a UE 510, via a wireless network access node, such as a base station or relay station or remote radio head, and more specifically shown as a gNodeB (gNB) 512. The network 501 may include a network element 514, which serves as a gateway to a broader network, such as a public switched telephone/data network and/or the Internet.

The UE 510 includes a controller, such as a computer or a data processor (DP) 510A, a computer-readable memory medium embodied as a memory (MEM) 510B, which stores a program of computer instructions (PROG) 510C, and a suitable radio frequency (RF) transmitter and receiver 510D for bi-directional wireless communications with the gNodeB (gNB) 512 via one or more antennas. The gNodeB 512 also includes a controller, such as a computer or a data processor (DP) 512 A, a computer-readable memory medium embodied as a memory (MEM) 512B that stores a program of computer instructions (PROG) 512C, and a suitable RF transmitter and receiver 512D for communication with the UE 510 via one or more antennas. The network element 514 also includes a controller, such as a computer or a data processor (DP) 514A, and a computer-readable memory medium embodied as a memory (MEM) 514B that stores a program of computer instructions (PROG) 514C. The gNodeB 512 is coupled via a data/control path 513 to the network element 514. The path 513 may be implemented as an S l interface when the network 501 is an LTE network. The gNodeB 512 may also be coupled to another gNodeB or to an eNodeB via data/control path 515, which may be implemented as an X2 interface when the network 501 is an LTE network.

At least one of the PROGs 510C, 512C, and 514C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 510A of the UE 510, and/or by the DP 512A of the gNodeB 512, and/or by the DP 514A of the NE 514, or by hardware, or by a combination of software and hardware (and firmware).

In general, the various embodiments of the EGE 510 can include, but are not limited to, cellular telephones; personal digital assistants (PDAs) having wireless communication capabilities; portable computers having wireless communication capabilities; image capture devices, such as digital cameras, having wireless communication capabilities; gaming devices having wireless communication capabilities; music storage and playback appliances having wireless communication capabilities; and Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The computer-readable MEMs 510B, 512B, and 514B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic- memory devices and systems, optical-memory devices and systems, fixed memory and removable memory. The DPs 510A, 512A, and 514A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples.

It should be noted that the various DPs 510A, 512A, 514A may be implemented as one or more processors/chips, either or both of the EGE 510 and the gNodeB 512 may include more than one transmitter and/or receiver 510D, 512D, and particularly the gNodeB 512 may have its antennas mounted remotely from the other components of the gNodeB 512, such as for example tower-mounted antennas.

Figure 6 shows an exemplary radio network in which the present invention may be practiced. In Figure 6, the 5GS architecture with regenerative satellite enabled NR-RAN, with Inter-Satellite Link (ISL) available between satellites (see 3GPP TR 23.737), is shown. This architecture is valid for constellations of both GEO and LEO satellites. In the example of Figure 6, the ISLs provide the Fl interface 602 between the different satellites 604 each implementing gNB-DU (distributed unit) functionalities. Further, at least one satellite is assumed to have an Fl interface to a Remote Radio Unit 606 on the ground. The Remote radio Unit 606 implements the gNB-CU (centralized unit) functionalities. The illustrated architecture allows for coordination by the gNB-CU of the spectrum frequency bands (fi, f₂, f₃, f₄) and coverage beams used on each of the satellites.

Figure 7 is a flow chart illustrating a method performed by a non-terrestrial base station in accordance with the present disclosure. In block 702, the non-terrestrial base station directs a radio beam of a plurality of radio beams toward a coverage area of the non terrestrial base station. In block 704, the non-terrestrial base station detects a potential increase in a capacity demand in the coverage area. In block 706, the non-terrestrial base station directs one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams. In block 708, the non-terrestrial base station detects a decrease in the capacity demand in the coverage area. And, in block 710, the non-terrestrial base station reduces the number of radio beams of the plurality of radio beams directed toward the coverage area.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto.

While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components, such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry, as well as possibly firmware, for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. For example, while the exemplary embodiments have been described above in the context of advancements to the 5G NR system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system. The exemplary embodiments of the invention presented herein are explanatory and not exhaustive or otherwise limiting of the scope of the invention.

The following abbreviations have been used in the preceding discussion:

ACK Acknowledgment (positive)

DL Downlink

FDD Frequency-Division-Duplex

GEO Geo -stationary orbit satellite (35786 km altitude orbit)

GHz Gigahertz

gNB gNodeB (5G eNB)

ISL Inter-Satellite Link

HAP High Altitude Platform

HAPS High Altitude Platform System (or Station) (8km to 50km altitude orbit)

ITU International Telecommunications Union

LEO Low orbit satellite (600km to 1500km altitude orbit)

MEO Medium orbit satellite (7000km to 20000km altitude orbit)

MHz Megahertz

NACK Negative Acknowledgment Non-GEO LEO/MEO/HAPS orbit satellites/platforms

NR New Radio

NW Network

RF Radio Frequency

SAT GEO/Non-GEO satellite or HAPS Satellite

SC Serving Cell

SINR Signal-to-Interference-and-Noise Ratio

SNR Signal-to-Noise Ratio

TC Target Cell

TDD T ime-Division-Duplex

UE User Equipment

UL Uplink

3 GPP 3^rd Generation Partnership Project

5G 5^th Generation

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms“a”,“an”, and“the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or“comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. Various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications of the teachings of this disclosure will still fall within the scope of the non-limiting embodiments of this invention.

Although described in the context of particular embodiments, it will be apparent to those skilled in the art that a number of modifications and various changes to these teachings may occur. Thus, while the invention has been particularly shown and described with respect to one or more embodiments thereof, it will be understood by those skilled in the art that certain modifications or changes may be made therein without departing from the scope of the invention as set forth above, or from the scope of the claims to follow.

Claims

WHAT IS CLAIMED IS:

1. A method comprising:

directing a radio beam of a plurality of radio beams toward a coverage area of a non terrestrial base station;

detecting a potential increase in a capacity demand in the coverage area;

directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams;

detecting a decrease in the capacity demand in the coverage area; and

reducing the number of radio beams of the plurality of radio beams directed toward the coverage area.

2. The method as claimed in claim 1 , wherein the individual radio beams have frequencies differing from one another.

3. The method as claimed in claim 1 or in claim 2, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an increase in a number of user equipments in the coverage area.

4. The method as claimed in any one of claims 1 to 3, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an entrance of one or more high-capacity users into the coverage area.

5. The method as claimed in any one of claims 1 to 4, wherein an increase in the number of radio beams directed toward the coverage area is triggered by interference caused by more than one user equipment using a given radio beam in the coverage area.

6. The method as claimed in any one of claims 1 to 5, wherein one radio beam of the plurality of radio beams is directed to follow a user equipment moving across the coverage area.

7. The method as claimed in any one of claims 1 to 6, wherein radio beams of the plurality of radio beams are directed toward separate regions of the coverage area.

8. The method as claimed in claim 7, further comprising:

communicating with a second non-terrestrial base station having a second coverage area neighboring said coverage area of said non-terrestrial base station to coordinate frequency reuse at a border between said coverage area and said second coverage area.

9. An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following:

direct a radio beam of a plurality of radio beams toward a coverage area of a non terrestrial base station;

detect a potential increase in a capacity demand in the coverage area;

direct one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams;

detect a decrease in the capacity demand in the coverage area; and

reduce the number of radio beams of the plurality of radio beams directed toward the coverage area.

10. The apparatus as claimed in claim 9, wherein the individual radio beams have frequencies differing from one another.

1 1. The apparatus as claimed in claim 9 or in claim 10, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an increase in a number of user equipments in the coverage area.

12. The apparatus as claimed in any one of claims 9 to 11 , wherein an increase in the number of radio beams directed toward the coverage area is triggered by an entrance of one or more high-capacity users into the coverage area.

13. The apparatus as claimed in any one of claims 9 to 12, wherein an increase in the number of radio beams directed toward the coverage area is triggered by interference caused by more than one user equipment using a given radio beam in the coverage area.

14. The apparatus as claimed in any one of claims 9 to 13, wherein one radio beam of the plurality of radio beams is directed to follow a user equipment moving across the coverage area.

15. The apparatus as claimed in any one of claims 9 to 14, wherein radio beams of the plurality of radio beams are directed toward separate regions of the coverage area.

16. The apparatus as claimed in claim 15, wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus to:

communicate with a second non-terrestrial base station having a second coverage area neighboring said coverage area of said non-terrestrial base station to coordinate frequency reuse at a border between said coverage area and said second coverage area.

17. An apparatus comprising:

means for directing a radio beam of a plurality of radio beams toward a coverage area of a non-terrestrial base station;

means for detecting a potential increase in a capacity demand in the coverage area; means for directing one or more additional radio beams of the plurality of radio beams toward the coverage area, wherein frequency reuse and narrow beams are employed to divide the coverage area into regions served by individual radio beams;

means for detecting a decrease in the capacity demand in the coverage area; and means for reducing the number of radio beams of the plurality of radio beams directed toward the coverage area.

18. The apparatus as claimed in claim 17, wherein the individual radio beams have frequencies differing from one another.

19. The apparatus as claimed in claim 17 or in claim 18, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an increase in a number of user equipments in the coverage area.

20. The apparatus as claimed in any one of claims 17 to 19, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an entrance of one or more high-capacity users into the coverage area.

21. The apparatus as claimed in any one of claims 17 to 20, wherein an increase in the number of radio beams directed toward the coverage area is triggered by interference caused by more than one user equipment using a given radio beam in the coverage area.

22. The apparatus as claimed in any one of claims 17 to 21 , wherein one radio beam of the plurality of radio beams is directed to follow a user equipment moving across the coverage area.

23. The apparatus as claimed in any one of claims 17 to 22, wherein radio beams of the plurality of radio beams are directed toward separate regions of the coverage area.

24. The apparatus as claimed in claim 23, further comprising:

means for communicating with a second non-terrestrial base station having a second coverage area neighboring said coverage area of said non-terrestrial base station to coordinate frequency reuse at a border between said coverage area and said second coverage area.

25. A computer program product comprising a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing:

directing a radio beam of a plurality of radio beams toward a coverage area of a non- terrestrial base station;

detecting a potential increase in a capacity demand in the coverage area;

detecting a decrease in the capacity demand in the coverage area; and

26. The computer program product as claimed in claim 25, wherein the individual radio beams have frequencies differing from one another.

27. The computer program product as claimed in claim 25 or in claim 26, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an increase in a number of user equipments in the coverage area.

28. The computer program product as claimed in any one of claims 25 to 27, wherein an increase in the number of radio beams directed toward the coverage area is triggered by an entrance of one or more high-capacity users into the coverage area.

29. The computer program product as claimed in any one of claims 25 to 28, wherein an increase in the number of radio beams directed toward the coverage area is triggered by interference caused by more than one user equipment using a given radio beam in the coverage area.

30. The computer program product as claimed in any one of claims 25 to 29, wherein one radio beam of the plurality of radio beams is directed to follow a user equipment moving across the coverage area.

31. The computer program product as claimed in any one of claims 25 to 30, wherein radio beams of the plurality of radio beams are directed toward separate regions of the coverage area.

32. The computer program product as claimed in claim 31 , wherein the computer program code further comprises code for performing: