EP-4736345-A1 - METHOD FOR SELECTING AT LEAST ONE MODULATION AND CODING SCHEME, CORRESPONDING TRANSMISSION METHOD, SELECTION DEVICE AND USER TERMINAL

EP4736345A1EP 4736345 A1EP4736345 A1EP 4736345A1EP-4736345-A1

Abstract

The invention relates to a method for selecting at least one MCS scheme suitable for being used by a user terminal for transmitting data on at least one subcarrier frequency, implementing a calibration phase comprising, for the at least one subcarrier frequency: - for at least one collaborator satellite and for at least one candidate MCS scheme, obtaining a result of a comparison (E5) between a target value of at least one parameter representing a use of the at least one subcarrier frequency for the candidate MCS scheme expected by the collaborator satellite, and an actual value of the at least one parameter, which value is measured by the collaborator satellite, and selecting (E6-2) at least one MCS scheme suitable for being used by the user terminal for the transmission of data on the at least one subcarrier frequency, among the at least one candidate MCS scheme, taking into account the comparison result(s) obtained.

Inventors

STEPHAN, EMILE
KELIF, JEAN-MARC

Assignees

ORANGE

Dates

Publication Date: 20260506
Application Date: 20240625

Claims (16)

1. A method for selecting at least one modulation and coding scheme capable of being used by a user terminal for transmitting data on at least one subcarrier frequency, said user terminal being located in a cell of a radio communication network served by at least one first satellite, called the master satellite, said method being implemented by said master satellite, a geostationary satellite, a high-orbit satellite or a low-orbit satellite, and implementing a calibration phase comprising, for said at least one subcarrier frequency: for at least one collaborating satellite of a group of collaborating satellites capable of collaborating with said master satellite to collect data transmitted by said user terminal and for at least one candidate modulation and coding scheme: • obtaining a result of a comparison (E5) between a target value of at least one parameter representing a use of said at least one subcarrier frequency for said candidate modulation and coding scheme expected by said collaborating satellite, and an effective value of said at least one parameter measured by said collaborating satellite, a selection (E6-2) of at least one modulation and coding scheme capable of being used by said user terminal for the transmission of data on said at least one subcarrier frequency, from among said at least one candidate modulation and coding scheme, taking into account the comparison result(s) obtained.
2. Method according to claim 1, characterized in that said selection selects at least one modulation and coding scheme making it possible to achieve the target value of said at least one parameter for a given minimum number of collaborating satellites.
3. Method according to claim 1, characterized in that said selection selects at least one modulation and coding scheme making it possible to achieve the target value of said at least one parameter for all of said subcarrier frequencies intended to be used to transmit said data.
4. Method according to any one of claims 1 to 3, characterized in that it comprises sending a calibration message (MSG3) identifying said at least one selected modulation and coding scheme and/or at least one prohibited modulation and coding scheme.
5. Method according to any one of the preceding claims, characterized in that it implements the sending (E2) of at least one parameterization message (MSG1) comprising technical information belonging to the group comprising: at least one FSPi subcarrier frequency authorized to be used during said calibration phase, at least one subcarrier frequency prohibited during said calibration phase, said at least one candidate modulation and coding scheme capable of being used by said user terminal to transmit data on said at least one FSPi subcarrier frequency, at least one modulation and coding scheme prohibited during said calibration phase, at least one symbol of a modulation associated with said at least one candidate modulation and coding scheme authorized to be transmitted during said calibration phase, at least one symbol of a modulation prohibited during said calibration phase.
6. Method according to claim 5, characterized in that it implements the reception (E3) of at least one test message (MSG2) carrying data transmitted on at least one subcarrier frequency modulated according to one of said candidate modulation and coding schemes, taking into account said at least one authorized symbol, identified in said at least one parameterization message (MSG1).
7. Method according to any one of the preceding claims, characterized in that it comprises the determination (E4) of said effective value of said at least one parameter representing a use of said at least one subcarrier frequency for said candidate modulation and coding scheme, from said at least one test message (MSG2).
8. Method according to any one of the preceding claims, characterized in that it comprises the determination of a subgroup of collaborating satellites taking into account the results of said comparison of said calibration phase obtained for at least two collaborating satellites.
9. Method according to any one of the preceding claims, characterized in that it comprises a determination of at least one phase, frequency and/or amplitude correction profile for said at least one modulation and coding scheme selected for said at least one subcarrier frequency.
10. Method according to claim 9, characterized in that it comprises sending said at least one correction profile, in said calibration message (MSG3) or in a separate message.
11. Method according to any one of the preceding claims, characterized in that said at least one parameter representing a use of said at least one subcarrier frequency belongs to the group comprising: at least one parameter representative of the transmission quality of said at least one subcarrier frequency; and the value of the phase and/or the amplitude of the constellation points conveyed by said at least one subcarrier frequency.
12. Device for selecting at least one modulation and coding scheme capable of being used by a user terminal for transmitting data on at least one subcarrier frequency, said user terminal being located in a cell of a radio communication network served by at least one first satellite, called the master satellite, said device comprising at least one processor configured to implement a calibration phase comprising, for said at least one subcarrier frequency: for at least one collaborating satellite of a group of collaborating satellites capable of collaborating with said master satellite to collect data transmitted by said user terminal and for at least one candidate modulation and coding scheme: • obtaining a result of a comparison (E5) between a target value of at least one parameter representing a use of said at least one subcarrier frequency for said candidate modulation and coding scheme expected by said collaborating satellite, and an actual value of said at least one parameter measured by said collaborating satellite, selecting (E6-2) at least one modulation and coding scheme capable of being used by said user terminal for the transmission of data on said at least one subcarrier frequency, from said at least one candidate modulation and coding scheme, taking into account the comparison result(s) obtained; said selection device belonging to a group comprising: said master satellite, a geostationary satellite, a high-orbit satellite, a low-orbit satellite.
13. A method for transmitting data on at least one subcarrier frequency, implemented by a user terminal located in a cell of a radio communication network served by at least one first satellite, called the master satellite, characterized in that it comprises: receiving, at the end of a calibration phase, at least one modulation and coding scheme selected from at least one candidate modulation and coding scheme, taking into account at least one comparison result between a target value of at least one parameter representing a use of said at least one subcarrier frequency for said candidate modulation and coding scheme expected by a collaborating satellite, and an actual value of said at least one parameter measured by said collaborating satellite, said collaborating satellite belonging to a group of collaborating satellites capable of collaborating with said master satellite to collect data transmitted by said user terminal, transmitting data on said at least one subcarrier frequency, modulated according to one of said at least one selected modulation and coding scheme.
14. Method according to claim 13, characterized in that said method comprises beforehand: the reception of at least one parameterization message (MSG1) comprising technical information belonging to the group comprising: • at least one FSPi subcarrier frequency authorized to be used during said calibration phase, at least one subcarrier frequency prohibited during said calibration phase, • at least one candidate modulation and coding scheme capable of being used by said user terminal to transmit data on said at least one FSPi subcarrier frequency, • at least one modulation and coding scheme prohibited during said calibration phase, • at least one symbol of a modulation associated with said at least one candidate modulation and coding scheme authorized to be emitted during said calibration phase, • at least one symbol of a modulation prohibited during said calibration phase, and for at least one authorized subcarrier frequency and for at least one candidate modulation and coding scheme: • sending (E2) at least one test message (MSG2) carrying data transmitted on said at least one subcarrier frequency modulated according to said candidate modulation and coding scheme, taking into account said at least one authorized symbol, identified in said at least one parameterization message (MSG1).
15. Method according to any one of claims 13 and 14, characterized in that it comprises the reception of at least one phase, frequency and/or amplitude correction profile for said at least one modulation and coding scheme selected for said at least one subcarrier frequency, and in that it implements a correction of said at least one subcarrier frequency modulated according to said at least one selected modulation and coding scheme taking into account said correction profile.
16. User terminal capable of transmitting data on at least one subcarrier frequency, when it is located in a cell of a radio communication network served by at least one first satellite, called master satellite, said terminal comprising at least one processor configured to: receive, at the end of a calibration phase, at least one modulation and coding scheme selected from at least one candidate modulation and coding scheme, taking into account at least one comparison result between a target value of at least one parameter representing a usage of said at least one subcarrier frequency for said candidate modulation and coding scheme expected by a collaborating satellite, and an effective value of said at least one parameter measured by said collaborating satellite, said collaborating satellite belonging to a group of collaborating satellites capable of collaborating with said master satellite to collect data transmitted by said user terminal, transmit data on said at least one subcarrier frequency, modulated according to one of said at least one selected modulation and coding scheme.

Description

DESCRIPTION TITLE: Method for selecting at least one modulation and coding scheme, corresponding transmission method, selection device and user terminal. Field of invention The field of the invention is that of satellite communications. More specifically, the invention relates to a solution for improving the performance of a radio access network whose access nodes are embedded in telecommunications satellites. The invention finds a very particular application when several satellites belonging or not to the same constellation of satellites collaborate with each other in order to improve the quality and performance of data transmission with a user terminal located in a cell of a communication network served by one of these satellites. Prior art and its drawbacks In recent years, the deployment of satellites, particularly in the form of satellite constellations consisting of several hundred to several thousand satellites in low orbit around the Earth, has been accelerating. The objective of such deployment of satellite constellations is, among other things, to provide user terminals with high-speed access to a communications network when access to the latter via terrestrial radio access networks is not satisfactory. A satellite constellation consists of a group of artificial satellites working together to provide a service, such as access to a communications network, by ensuring the most complete possible ground coverage of the Earth's surface in order to ensure continuity in the provision of this service. To this end, a satellite carries at least one access node of a radio access network interconnected to a core network. Furthermore, each satellite belonging to the same constellation circulates on orbits and trajectories chosen so that all the ground coverages of each of the satellites in the constellation complement each other. The resources of a satellite are not used continuously over time. Indeed, a satellite may be required to fly over desert areas, aquatic surfaces, forests or agricultural areas, in which few, if any, user terminals are located. Thus, the radio communication resources of these satellites are free over many time slots. In order to be able to exploit these radio communication resources, cooperation between several satellites of the same constellation or belonging to different constellations can be envisaged. Thus, a satellite belonging to a first constellation flying over an area in which there is no communication terminal to be served can share its radio communication resources with another satellite belonging to a second constellation located in a position in its orbit that is not not allowing it to optimally serve a given radio cell because its distance and/or its degree of inclination relative to the ground surface of this radio cell, and to the air zone attached to this surface, does not offer sufficient transmission conditions to guarantee an acceptable quality of service to the communication terminals located within this radio cell. As the satellites move relative to each other and to the user terminals with which they exchange data, this impacts the transmission of radio signals exchanged between these different entities. The effects generated by the movement of the satellites may, for example, consist of a phase shift of the radio signals exchanged, a modification of the amplitude of one or more of these radio signals, or a frequency shift, for example due to the Doppler effect, of the radio signals. This results in a reduction in the performance of the radio access network. There is therefore a need for a technique to overcome all or part of the above-mentioned drawbacks. Disclosure of the invention The invention proposes a novel solution in the form of a method for selecting at least one modulation and coding scheme capable of being used by a user terminal for transmitting data on at least one subcarrier frequency, said user terminal being located in a cell of a radio communication network served by at least one first satellite, called the master satellite, said method implementing a calibration phase comprising, for said at least one subcarrier frequency: for at least one collaborating satellite of a group of collaborating satellites capable of collaborating with said master satellite to collect data transmitted by said user terminal and for at least one candidate modulation and coding scheme: - obtaining a result of a comparison between a target value of at least one parameter representing a use of said at least one subcarrier frequency for said candidate modulation and coding scheme expected by said collaborating satellite, and an effective value of said at least one parameter measured by said collaborating satellite, a selection of at least one modulation and coding scheme capable of being used by said user terminal for the transmission of data on said at least one subcarrier frequency, from among said at least one candidate modulation and coding scheme, taking into accoun