Method, implemented by an air or space device, for communicating with at least one terminal, and associated device, system and computer program

Abstract

The present invention relates to a method, implemented by a first air or space device (SAT_X), for transmitting data to at least one terminal (UE), the method comprising: - receiving (SX60), from a cooperation entity (GW, BROKER), information (COOP_DIM) relating to resources of at least one second air or space device (SAT_Y), said resources being able to be used to transmit data to said at least one terminal (UE); - if a cooperation criterion (COOP_CRIT) is satisfied, triggering cooperation with said at least one second device (SAT_Y) on the basis of said information (COOP_DIM) in order to transmit data to said at least one terminal (UE), said cooperation comprising: sending (SX120) second data (COOP_DATA), to be transmitted to said at least one terminal (UE), to said at least one second device (SAT_Y).

Description

Description Title of the invention: A method implemented by an aerial or space-based device to communicate with at least one associated terminal, device, system, and computer program technical field

[0001] The present invention relates to the general field of telecommunications, and more particularly to the field of communications via aerial or space-based devices such as satellites or aircraft (e.g., drones). Specifically, the present invention relates to a method implemented by an aerial or space-based device to communicate with at least one terminal and a method implemented by a cooperation entity to communicate with an aerial or space-based device, as well as an associated device, cooperation entity, system, computer program, and information medium. The present invention finds a particularly advantageous, though not limiting, application in the implementation of satellite mobile telephony networks. Prior art

[0002] The growing demand from users for wireless connectivity with global coverage has led to the emergence of satellite communication systems. Currently, various communication systems using satellites exist, allowing users to access a network (e.g., the Iridium or Viasat network) regardless of their location. However, operating satellite communication systems requires addressing latency and coverage issues.

[0003] Generally speaking, it is known to use satellites in geostationary orbit to deploy satellite communication systems. Geostationary satellites remain in a fixed position in the sky, allowing for large, fixed coverage areas. However, these advantages are offset by several drawbacks. Geostationary satellites are located at an altitude of approximately 36,000 km, so the ground-to-satellite distance results in high latency and requires significant transmission power. Furthermore, there is no way to reduce this latency, which is inherent to the round-trip propagation time of signals between Earth and geostationary satellites.

[0004] For these reasons, communication systems using satellites in medium or low Earth orbit have been developed. Compared to geostationary satellites, the distance between the ground and satellites in medium or low Earth orbit is much greater. Low Earth orbit (LEO) latency is significantly shorter. Consequently, communication systems based on satellites in medium or low Earth orbit do not suffer from the aforementioned drawbacks of latency and transmission power. However, it should be noted that such communication systems each require a constellation of a large number of satellites to provide users with continuous geographic coverage, resulting in significant implementation complexity.

[0005] There is therefore a need for a satellite communication system capable of covering a large geographical area and communicating with terminals efficiently, in terms of throughput, reliability, and latency. Description of the invention

[0006] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those previously described.

[0007] To this end, according to one aspect of the invention, a method is proposed implemented by a first airborne or space-based device to transmit data to at least one terminal, the method comprising: receiving, from a cooperation entity, information relating to resources of at least a second airborne or space-based device that can be used to transmit data to at least one terminal; if a criterion called cooperation is met, triggering cooperation with said at least a second device based on said information to transmit data to at least one terminal, said cooperation comprising sending, to at least a second device, data called second data to be transmitted to at least one terminal.

[0008] For the purposes of this invention, the term "aerial or space device" refers to any device capable of rising into the air, such as a drone or a high-altitude platform, or to any device placed in orbit around a planet (Earth, Mars, etc.), such as artificial satellites (e.g., telecommunications satellites). In one particular embodiment, the first and second devices are satellites.

[0009] Within the framework of the invention, the "cooperation entity" refers to an entity that determines and transmits said information relating to the resources of said at least one second device, enabling cooperation between airborne or spaceborne devices if relevant. This cooperation entity may be comprised of a ground station, an airborne or spaceborne device management entity, or an airborne or spaceborne device.

[0010] The term "resource" here refers to a communication resource, which can designate any type of resource that can be used to communicate data, such as a frequency channel, a time slot, a frequency-time slot combination, etc. The term "cooperation" is used hereafter to describe the fact that several airborne or space-based devices are involved in communication with at least one terminal, and more specifically, collaborate to transmit data to it. For example, cooperation between several satellites might involve the transmission of data from a first satellite to a terminal using a second satellite as a relay (i.e., a satellite repeater). Another example is inter-satellite cooperation, which might involve the simultaneous transmission of data from a first and a second satellite to a terminal.

[0011] The term "cell" is used here to designate a terrestrial geographic region covered by a beam emitted by an aerial or space-based communication device. A cell thus refers to a geographic area on Earth in which a beam (more commonly referred to by the English term "spot") emitted by an aerial or space-based device can carry (i.e., communicate) data. Each device is capable of emitting multiple beams and therefore covering multiple cells. More specifically, a cell can correspond to a coverage area, i.e., a geographic area in which the signal strength level received by a terminal exceeds a certain threshold. For example, the signal strength level received by the terminal is similar to that of a terrestrial 4G or 5G cell, allowing a direct connection from a standard mobile device.By extension, the term "cell" also refers to the lower part of the beam cone immediately above this terrestrial geographic area, capable of containing mobile, onboard flying terminals such as drones flying at a maximum altitude of a few hundred meters. In the context of the invention, the satellites can be in geostationary, medium, or low Earth orbits, such that the coverage areas of the different satellites can be fixed or mobile over time.

[0012] By "cooperation criterion", it is understood here as a criterion which conditions the implementation of cooperation between the first device and the second device for the transmission of data to the terminal.

[0013] The proposed process makes it possible to improve the performance of a satellite communication system (e.g. a satellite access network), particularly in terms of coverage, throughput and reliability.

[0014] Indeed, the proposed method enables cooperation between aerial or space-based devices to communicate with terminals. For example, several satellites can be used to transmit data to the same terminal. Hereafter, the resources of an air or space device that can be used for cooperation are also referred to as shareable or usable resources.

[0015] Such cooperation allows the first device to benefit from the resources of the second device to transmit data to a terminal. In particular, such cooperation can allow the first device to maintain and / or artificially increase its coverage area.

[0016] Indeed, the first device can benefit, through cooperation, from the coverage area of ​​the second device to communicate with terminals.

[0017] The proposed method makes it possible, for example, to increase the power of the signal received by a terminal and thus improve the signal-to-noise ratio (SINR) at the receiving terminal. For instance, a first satellite can increase the power of the signal received by a terminal by cooperating with a second relay satellite (i.e., a satellite repeater) located closer to the terminal. In other words, the first device transmits data to a terminal via the second device. Consequently, the proposed method can improve the reliability and / or throughput of communications. In the context of the invention, improved communication reliability specifically refers to a reduction in the probability of transmission errors.

[0018] Furthermore, the proposed method allows the first device to implement cooperation autonomously and dynamically, thus enabling it to respond to rapid variations in data rates transmitted to terminals. The invention requires only minimal, asynchronous signaling between a ground station and the airborne or space-based devices to implement cooperation, thereby allowing the deployment of an aircraft or satellite communication system with a limited number of ground stations.

[0019] Furthermore, the process enables cooperation between aircraft or satellites belonging to different constellations without the control entities (e.g., ground stations) of one constellation taking control of the aircraft or satellites of another constellation. A constellation is also understood to mean any set of aircraft or satellites operated by the same administrative entity (e.g., the same aircraft or satellite operator) to provide at least one given service (e.g., communications service) and managed by one or more control entities operated by or for that administrative entity.

[0020] Autonomy, meaning the ability of air or space-based systems to initiate cooperation, is enabled by sending the first system information about the second system's resources that can be used for cooperation. Indeed, upon receiving this information, the first system has the necessary resources. Information required to initiate cooperation, if necessary. Furthermore, it should be emphasized that the step of receiving this information regarding the usable resources of the second device can be carried out asynchronously, i.e., without time constraints, relative to the step of sending the second data to the second device. For example, the information received by the first device might indicate that the second device has shareable resources available for a given period of time (e.g., 1 minute, 1 hour, 1 day, etc.). Thus, at any point during this period, the first device can initiate cooperation with the second device. The sending of this information by the cooperating entity to the first device is therefore not time-constrained.The proposed method therefore makes it possible to implement a low-complexity communication system to achieve cooperation between aerial or space-based devices.

[0021] According to one embodiment, the first device sends at least a second device a request for cooperation to transmit data to at least one terminal, the request for cooperation including control data for the implementation of said cooperation.

[0022] The sending of the cooperation request by the first device to the second device can be carried out simultaneously with the sending of said second data to be transmitted to the terminal, or in a desynchronized manner.

[0023] In particular, according to this last embodiment, the first device initiates cooperation by issuing a so-called cooperation request to the second device, then sends the second device the data to be relayed to the terminals. Typically, the data to be communicated to the terminals is application data with constraints on the transmission time between the sender of this data and the terminal, e.g. data from a telephone or Internet communication, whether hosted or not (application functions such as edge computing, content delivery networks (CDNs), clock synchronization, key distribution for authentication functions, background service data broadcasting, etc.) by the first device.Thus, the prior submission of a cooperation request allows the second device to allocate resources for cooperation independently of time constraints on the application data. Furthermore, the cooperation request includes the control data (e.g., synchronization data, power and emission spectra, etc.) necessary for cooperation, and its transmission, according to this embodiment, is independent of time constraints on the application data to be transmitted to the terminals.

[0024] This method of implementation thus makes it possible to reduce the complexity of implementing cooperation between aerial or space-based devices.

[0025] According to one embodiment, the information relating to the resources of said at least one second device that can be used is updated, that is to say, refreshed, by said cooperation entity.

[0026] In one embodiment, the first device sends initial data to at least one terminal, using a time-frequency resource that is also used by at least one second device to transmit the second data to at least one terminal. It should be noted that the initial and second data sent by the first and second devices, respectively, may be identical or different.

[0027] Hereafter, we use the term "communication channel" to refer to the transmission medium used to communicate data between aerial or space-based devices and the terminal. More specifically, the term "communication channel" refers to a wireless communication channel.

[0028] In this embodiment, a plurality of point-to-point links are used to transmit data to terminals. This embodiment thus enables the use of coordinated multi-point (CoMP) techniques. By exploiting the spatial domain of the communication channel between the airborne or space-based devices and the terminal, this embodiment allows users to benefit from the respective advantages of spatial diversity and spatial multiplexing schemes. More specifically, spatial diversity techniques consist of sending or receiving redundant information streams in parallel over multiple spatial channels to increase the reliability and range of communications; and spatial multiplexing techniques consist of sending or receiving independent information streams in parallel over multiple spatial channels to increase data rate.Therefore, this embodiment makes it possible to improve communication performance in terms of coverage, throughput and reliability.

[0029] According to one embodiment, the first device sends first data to at least one terminal, using a time-frequency resource different from a time-frequency resource used by said at least a second device to transmit the second data to at least one terminal.

[0030] This embodiment allows for the implementation of frequency and / or time-division multiplexing techniques, thereby increasing the communication throughput. Indeed, in this embodiment, the first device benefits, through the cooperation of the second device, from additional frequency and / or time resources to transmit data to at least one terminal.

[0031] According to one embodiment, the first and second devices belong to the same constellation.

[0032] Thus, in this embodiment, the first and second devices are operated, for example, by the same aircraft or satellite operator. In this embodiment, the first and second devices can be configured to communicate with the same ground station. In particular, the first device receives the first and / or second data from this ground station. However, it is also possible within the scope of the invention for the first and second data to be generated by the first device, for example, by providing data from a cache embedded in the first device.

[0033] This embodiment enables simple and dynamic cooperation between airborne or spaceborne devices within the same constellation to improve the communication performance of an aircraft or satellite communication system (e.g., a satellite access network). Furthermore, as mentioned previously, the proposed method allows for cooperation with a low-complexity architecture, requiring only limited signaling between the ground station and the airborne or spaceborne devices.

[0034] According to one embodiment, the first and said at least a second device belong to different constellations.

[0035] In this embodiment, the first and second devices are typically operated by separate operators and configured to communicate with separate ground stations, with the first satellite able to receive first data and / or second data from the ground station with which it is configured to communicate.

[0036] This implementation method allows for simple and dynamic cooperation between satellites from different constellations with a low-complexity architecture.

[0037] In one embodiment, the first device receives information, for example, information relating to a power level received by at least one terminal, the cooperation criterion being determined by the first device based on this information. In particular, this information may be sent to the first device by a terminal (e.g., the at least one terminal in question), or by a ground station, or by the cooperation entity. When cooperation is initiated by the terminal sending the information, a cost incurred by the cooperation may be charged directly or indirectly to the terminal.

[0038] There are no limitations on the nature of the information relating to a received power level. It can take the form of a request to increase the received power, a received power level, or an indication that the received power level is below a given threshold.

[0039] This embodiment allows cooperation to be initiated based on the signal strength received by the terminals. For example, if the power received by the terminals is insufficient to implement communications with the required specifications, such as throughput and / or reliability, then the first device initiates cooperation with the second device to increase the power received by the terminals and / or to increase the time-frequency resources used to communicate with the terminals.

[0040] According to one embodiment, the first device sends, to a tracking entity, one or more proofs of use indicating resources used by the first device and / or said at least a second device to communicate with said at least a terminal.

[0041] This embodiment enables reliable and precise traceability of the resources used by a communication system implementing cooperation between airborne or space-based devices (e.g., aircraft or satellites) to communicate data to a terminal. Indeed, the proposed method allows an airborne or space-based device to dynamically inform a tracking entity of the resources used. It is thus possible to track the resources used by multiple airborne or space-based devices to communicate data to terminals.

[0042] According to another aspect of the invention, a method is proposed implemented by a cooperation entity to communicate with a first airborne or space device, the method comprising: determining information relating to resources of at least a second airborne or space device that can be used to transmit data to at least one terminal; sending said information to the first device.

[0043] The proposed process implemented by the cooperation entity has the advantages described above in relation to the proposed process implemented by an aerial or space-based device.

[0044] According to one embodiment, said information relating to the resources of said at least one second device that can be used is determined from at least one target data transmission rate and at least one probability of non-coverage defined for at least one communication service implemented by the second device.

[0045] By "target throughput," we refer here to a data transmission rate that is intended or must be achieved, for example, to implement a communication service (i.e., a function) with a certain quality of service. And, by "outage probability," we refer here, for a given target throughput, to a probability that a communication system may not be able to deliver that target throughput in a given geographical area, for example due to the variable capacity of the channel.

[0046] This embodiment avoids penalizing the implementation of a communication service provided by the second device with a certain quality of service. For example, if the second device only uses a portion of its resources to implement the service according to specifications (i.e., target data rate of user equipment covered by the second satellite and benefiting from this service, and probability of non-coverage of this user equipment), then the remaining resources of the second device are determined to be available for cooperation with other airborne or space-based devices.

[0047] According to one embodiment, the proposed method comprises one or more iterations of an update of said information relating to the resources of said at least one second device that can be used from at least one adjusted flow rate, said at least one adjusted flow rate being obtained from said at least one target flow rate and a coefficient.

[0048] This embodiment makes it possible to determine the resources of the second device that can be used for cooperation while maintaining a throughput close to the target throughput for a maximum number of simultaneous connections. Thus, this embodiment ensures the availability of a minimum of resources from the second device to implement cooperation with other aerial or space-based devices.

[0049] In one embodiment, the information relating to the resources of said at least one second device that can be used is determined from a plurality of target data rates and a plurality of non-coverage probabilities. For example, the target data rates and non-coverage probabilities relate to a plurality of communication services implemented by the communication system.

[0050] The advantage of this embodiment is to ensure that communication services are implemented by the communication system in accordance with the specifications (i.e., the defined quality of service).

[0051] According to one embodiment, said information relating to the resources of said at least one second device that can be used is determined from a statistic of the communication channel between said at least one second device and said at least one terminal for one or more beams emitted by said at least one second satellite.

[0052] The term "a statistic of a communication channel" here refers to a parameter of a statistical model of the communication channel. For example, the process proposed can exploit a standard deviation o, used as a parameter of a channel model to describe obstruction phenomena (or "shadowing" in English).

[0053] This embodiment allows for the statistical description of signal propagation phenomena between aerial or space-based devices and terminals. Among other things, multipath propagation, obstruction by obstacles, and meteorological conditions (e.g., precipitation) can lead to variable channel capacity. Consequently, this embodiment makes it possible to account for the variability of the power level received by the terminals to determine the available resources for cooperation.

[0054] In one embodiment, the process implemented by the cooperation entity comprises: - a transmission, to the first device (SAT_X), of data (DATA_T2) to be transmitted to said at least one terminal (UE), this data (DATA_T2) being transmitted to said at least one terminal (UE) via said at least a second device (SAT_Y); then - a sending, to a third air or space device (SAT_Z), of data (DATA_T3) to be transmitted to said at least one terminal (UE).

[0055] In this embodiment, inter-satellite cooperation allows the second air or space device to be used as a relay during a transfer of terminal control from the first air or space device to the third air or space device. This embodiment allows the first device to benefit from the resources of the second device to transmit data to the terminal until the terminal comes under the control of the third air or space device. This embodiment thus makes it possible, in particular, to artificially extend the coverage area of ​​the communication system and ensure continuity of service for the terminals. This transfer of control can enable the implementation of a data roaming mechanism and is referred to as "long handover" (or long intercellular handover) when this roaming involves another mobile service operator.According to another aspect of the invention, an air or space device, referred to as the first device, is proposed, adapted to transmit data to at least one terminal, said first device comprising: a receiving module configured to receive, from a cooperation entity, information relating to resources of at least a second air or space device that can be used to transmit data to said at least one terminal; a sending module configured to, if a cooperation criterion is met, trigger cooperation with said at least second device based on said information to transmit data to said at least one terminal, said cooperation comprising sending by the sending module to said at least a second. data device, called second data, to be transmitted to at least one terminal.

[0056] The proposed aerial or space device has the advantages described above in connection with the proposed process implemented by an aerial or space device.

[0057] According to one embodiment, said first device includes a determination module configured to determine a cooperation criterion.

[0058] According to one aspect of the invention, a cooperation entity adapted to communicate with a first airborne or space-based device is proposed, the cooperation entity comprising: a determination module configured to determine information relating to resources of at least a second airborne or space-based device that can be used to transmit data to at least one terminal; a sending module configured to send said information to the first device.

[0059] According to one embodiment, the cooperation entity is contained within a ground station.

[0060] According to one aspect of the invention, a communication system is proposed comprising: a first aerial or space device conforming to the invention; and at least a second aerial or space device comprising a receiving module configured to receive, from the first device, second data and a sending module configured to send, to at least one terminal, the second data.

[0061] The characteristics and advantages of the methods according to the present invention described above also apply to the proposed communication system and vice versa.

[0062] According to one embodiment, the communication system comprises: a cooperation entity according to the invention; and / or at least one terminal comprising a receiving module configured to receive data from said at least one second device.

[0063] According to one aspect of the invention, a computer program is proposed comprising instructions for carrying out the steps of a process according to the invention, when the computer program is executed by at least one processor or computer.

[0064] A computer program can consist of one or more sub-parts stored in the same memory or in separate memories. The program can use any programming language and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0065] According to one aspect of the invention, a computer-readable information carrier is proposed, comprising a computer program conforming to the invention.

[0066] The information carrier can be any entity or device capable of storing the program. For example, the carrier can include a storage means, such as non-volatile memory or ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard disk drive. Alternatively, the storage carrier can be a transmissible medium such as an electrical or optical signal, which can be transmitted via an electrical or optical cable, by radio, by a telecommunications network, by a computer network, or by other means. The program according to the invention can, in particular, be uploaded to a computer network. Alternatively, the information carrier can be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the process in question. Brief description of the drawings

[0067] Other features and advantages of the present invention will become apparent from the following description of embodiments of the invention. These embodiments are given by way of illustration and are not intended to be limiting. The following description is illustrated by the accompanying drawings:

[0068] [Fig. 1] Figure 1 schematically represents a communication system according to one embodiment of the invention;

[0069] [Fig. 2] Figure 2 schematically represents a communication system according to one embodiment of the invention;

[0070] [Fig. 3] Figure 3 schematically represents a communication system according to one embodiment of the invention;

[0071] [Fig. 4] Figure 4 schematically represents a communication system according to one embodiment of the invention;

[0072] [Fig. 5] Figure 5 represents, in the form of a flowchart, the steps of a communication process according to one embodiment of the invention;

[0073] [Fig. 6] Figure 6 schematically represents an example of information obtained and processed by a communication system according to one embodiment of the invention;

[0074] [Fig. 7] Figure 7 represents, in the form of a flowchart, the steps of a communication process according to one embodiment of the invention;

[0075] [Fig. 8] Figure 8 represents, in the form of a flowchart, the steps of a communication process according to one embodiment of the invention;

[0076] [Fig. 9] Figure 9 schematically represents an example of the software and hardware architecture of a communication system according to one embodiment of the invention;

[0077] [Fig. 10] Figure 10 schematically represents an example of the functional architecture of a communication system according to one embodiment of the invention. Description of the implementation methods

[0078] The present invention relates to a method implemented by an airborne or space-based device to communicate with at least one terminal and a method implemented by a cooperation entity to communicate with an airborne or space-based device, as well as an airborne or space-based device, a cooperation entity, a system, a computer program and an associated information medium.

[0079] Figure 1 schematically represents a communication system according to one embodiment of the invention.

[0080] As illustrated in Figure 1, the SYS satellite communication system comprises, in one embodiment: a ground station GW; a first satellite SAT_X; a second satellite SAT_Y; and at least one UE terminal. The communication system implements one or more satellite communication services. In particular, the SAT_X and SAT_Y satellites can implement the same communication service or different communication services. The communication system transmits data from a communication network NET to at least one UE terminal. To do this, the communication system implements inter-satellite cooperation; in other words, several SAT_X and SAT_Y satellites of the communication system collaborate to transmit data to at least one UE terminal.

[0081] According to this embodiment, inter-satellite cooperation is of the relay type, with the second satellite SAT_Y operating as a relay (i.e., repeater) between the first satellite SAT_X and at least one UE terminal. In other words, the first satellite SAT_X transmits data to at least one UE terminal via the second satellite SAT_Y. This embodiment allows the first satellite SAT_X to leverage the resources of the second satellite SAT_Y to transmit data to the UE terminal. This embodiment makes it possible, for example, to artificially extend the coverage area of ​​the communication system, as the first satellite SAT_X can utilize the coverage area of ​​the second satellite SAT_Y. to communicate with UE terminals. Furthermore, this embodiment allows for increasing the signal strength received by said at least one UE terminal, typically by selecting a SAT_Y relay satellite closer to said at least one UE terminal, thereby improving the reliability and / or throughput of communications. Said at least one UE terminal is thus located in the CELL cell of the second SAT_Y satellite.

[0082] According to this embodiment, the GW ground station is configured to communicate with the NET communication network. The GW ground station sends COOP_DIM information to the first satellite, SAT_X, regarding available resources on the second satellite, SAT_Y, that can be used to transmit data within the CELL cell, and thus be used in cooperation with the first satellite. In one example implementation, the COOP_DIM information corresponds to the number of available frequency channels on the second satellite, SAT_Y. The GW ground station also sends COOP_DATA data to the first satellite, SAT_X, to be communicated to at least one UE terminal.

[0083] According to this embodiment, the first satellite SAT_X receives, from the ground station GW, the COOP_DIM information and the COOP_DATA data to be communicated to the UE terminal, independently or simultaneously.

[0084] Based on the COOP_DIM available resource information, the first satellite, SAT_X, sends a COOP_QUERY cooperation request to the second satellite, SAT_Y, to transmit data to at least one UE terminal, followed by the COOP_DATA data to be transmitted to at least one UE terminal. Hereinafter, the COOP_QUERY cooperation request is also referred to as a data transmission request to at least one UE terminal. It should be noted that the sending of the COOP_QUERY cooperation request is not synchronous with the reception of the COOP_DIM available resource information. In fact, the first satellite, SAT_X, sends a COOP_QUERY cooperation request if it determines, in particular, that data transmission requires it, as detailed in Figure 5.

[0085] In one implementation example, the COOP_DIM information indicates that the second satellite, SAT_Y, has a plurality of free channels available for transmitting data within the CELL. In another embodiment, the COOP_DIM information indicates the number of available frequency channels for a given probability of no coverage. Based on this COOP_DIM information, the first satellite, SAT_X, requests the second satellite, SAT_Y, to communicate the COOP_DATA data to at least one UE terminal in order to adjust the reliability and / or throughput of communications. Specifically, this is to maintain an acceptable level of communication service.

[0086] According to this embodiment, the second satellite SAT_Y receives, from the first satellite SAT_X, the COOP_QUERY cooperation request and the COOP_DATA data to transmit to at least one UE terminal. Following this reception, the second satellite SAT_Y sends, to at least one UE terminal, the COOP_DATA data.

[0087] According to this embodiment, said at least one UE terminal receives, from the second satellite SAT_Y, the COOP_DATA data to be transmitted to the UE terminal.

[0088] The invention thus enables inter-satellite cooperation initiated autonomously by the satellites themselves. Consequently, the invention requires minimal communication between the ground station and the satellites to implement cooperation, thereby allowing the deployment of a satellite communication system with a limited number of ground stations.

[0089] For illustrative purposes, the present invention can be used to implement mobile telephone networks based on OFDMA (Orthogonal Frequency Division Multiple Access) type radio access technologies.

[0090] The satellites' autonomy in implementing cooperation is enabled by sending information about available COOP_DIM resources and updates to them. Indeed, upon receiving COOP_DIM information, the satellites have the necessary information to initiate cooperation if needed. Furthermore, it should be noted that the transmission of COOP_DIM resource information can be asynchronous, i.e., without time constraints, relative to the transmission of COOP_DATA to the UE terminal. This implementation reduces the time constraints on the communication system for implementing inter-satellite cooperation. This implementation allows for opportunistic and dynamic use of inter-satellite cooperation and enables rapid response to changes in data rates.

[0091] The following example illustrates this latter embodiment and is not exhaustive. The COOP_DIM information regarding available resources is sent to the first satellite, SAT_X, indicating that the second satellite, SAT_Y, has resources available for cooperation for a given period (e.g., one hour, one day, etc.). Thus, at any point during this period, the first satellite, SAT_X, can initiate cooperation with the second satellite, SAT_Y. Typically, the COOP_DATA to be communicated to a UE terminal is application data with constraints on the transmission time between the sender of this data and the terminal, e.g., data from a telephone call or a web browser session.

[0092] There are no limitations attached to the nature of the NET communication network, which can be a mobile phone network (2G, 3G, 4G, 5G, 6G, etc.), an Internet-type computer network, or any other network (proprietary, etc.) that may be considered. The interface of communication between the NET network and the GW ground station can be wired or wireless, and can implement any protocol known to a person skilled in the art.

[0093] No limitations are attached to the nature of the communication interfaces between the GW ground station and the first SAT_X satellite, nor between the first SAT_X satellite and the second SAT_Y satellite. In particular, according to one embodiment, one or more intermediate satellites are used to relay data from the GW ground station to the first SAT_X satellite and / or from the first SAT_X satellite to the second SAT_Y satellite.

[0094] According to the invention, the satellites of the SYS communication system can follow geostationary, medium, or low Earth orbits. Therefore, the coverage areas of the different satellites can be fixed or dynamic over time. Furthermore, it is important to note that the satellites of the communication system can be operated by the same satellite operator or by different satellite operators. In the latter case, the communication system allows for cooperation between several mobile and / or satellite operators.

[0095] UE terminals can be of the mobile phone type, for example a Smartphone, or a tablet, or a computer or any other type of communicating device such as IoT devices.

[0096] Figure 2 schematically represents a communication system according to one embodiment of the invention.

[0097] In one embodiment, the inter-satellite cooperation implemented by the communication system is of the CoMP type (Coordinated Multi-Point). According to this embodiment, the first satellite SAT_X and the second satellite SAT_Y are used to transmit data in a coordinated manner to at least one UE terminal, using the same time-frequency resources. This embodiment allows the spatial domain of the communication channel to be exploited to improve communication performance in terms of coverage, throughput, and / or reliability.

[0098] For example, according to the embodiment illustrated in Figure 2, the first satellite SAT_X and the second satellite SAT_Y send DATA_X and COOP_DATA data to at least one UE terminal using the same time-frequency block (CH1, T1). The notation (CH1, T1) is used here to denote a pair consisting of a frequency channel CH1 and a transmission time interval T1. According to this embodiment, the SAT_X and SAT_Y satellites coordinate their transmissions so that, at the at least one UE terminal, the reception of DATA_X data from the first satellite SAT_X is synchronized with the reception of COOP_DATA data from the second satellite SAT_Y. According to this embodiment, the COOP_QUERY cooperation request includes data from controls necessary for the coordination of the SAT_X and SAT_Y satellites, for example the emission offset times determined from the positions of the satellites and the cell.

[0099] A UE terminal may have one or more receiving antennas. In one embodiment, the UE terminal has a single antenna, resulting in a communication system described as a MISO (Multiple-Input Single-Output) system. In another embodiment, a UE terminal has multiple antennas, resulting in a communication system described as a MIMO (Multiple-Input Multiple-Output) system.

[0100] There are no limitations on the nature of the DATA_X and COOP_DATA data transmitted by the first satellite SAT_X and the second satellite SAT_Y, respectively; they may be identical or different. It should be noted that, in one embodiment, the COOP_DATA and DATA_X data are included within the DATA data.

[0101] According to a first example of implementation, the DATA_X and COOP_DATA data are identical, with CoMP-type inter-satellite cooperation being used to increase the power of the received signal.

[0102] In a second embodiment, the DATA_X and COOP_DATA data are different. In this example, CoMP-type inter-satellite cooperation is used to implement spatial multiplexing by sending independent DATA_X and COOP_DATA data in parallel over several spatial channels, thereby increasing the transmission rate.

[0103] According to a third example, the DATA_X and COOP_DATA data are different. In this example, CoMP-type inter-satellite cooperation exploits the spatial diversity of the channel by sending redundant DATA_X and COOP_DATA data in parallel over multiple spatial paths to increase the reliability and range of communications.

[0104] Figure 3 schematically represents a communication system according to one embodiment of the invention.

[0105] According to this embodiment, the inter-satellite cooperation implemented by the communication system is of the carrier aggregation type. In this mode, the first SAT_X and the second satellite SAT_Y are used to simultaneously send data to at least one UE terminal, using different frequency resources. This embodiment allows for frequency multiplexing, thereby improving the transmission rate.

[0106] For example, according to the embodiment illustrated in Figure 3, the first satellite SAT_X transmits DATA_X data to at least one UE terminal using a time-frequency block (CH1, T1); and the second satellite SAT_Y transmits at least one The UE terminal uses COOP_DATA data with a different time-frequency block (CH2, T1). Naturally, there are no limitations on the nature of the DATA_X and COOP_DATA data, which can be identical or different.

[0107] Figure 4 schematically represents a communication system according to one embodiment of the invention.

[0108] According to the embodiment illustrated in Figure 4, inter-satellite cooperation involves using the second satellite, SAT_Y, as a relay to transfer control of at least one terminal from the first satellite, SAT_X, to a third satellite, SAT_Z. In this embodiment, it is assumed that the SAT_X and SAT_Z satellites belong to the same constellation, and that the SAT_Y satellite belongs to a different constellation than the SAT_X and SAT_Z satellites. This embodiment allows the first satellite, SAT_X, to utilize the resources of the second satellite, SAT_Y, to transmit data to the UE terminal. This embodiment, for example, makes it possible to artificially extend the coverage area of ​​the communication system and ensure continuity of service for the terminals.In particular, the transfer of control is described as "long handover" (or long intercellular handover) in that it includes data roaming via another mobile network operator (MNO).

[0109] Figure 4 illustrates an embodiment in which a transfer of control includes the following steps: during a time interval T1, the first satellite SAT_X transmits DATA_T1 audit data to at least one UE terminal; during a time interval T2, the second satellite SAT_Y transmits DATA_T2 audit data to at least one UE terminal; during a time interval T3, the third satellite SAT_Z transmits DATA_T3 audit data to at least one UE terminal.

[0110] The example of a long intercell handover illustrated in Figure 4 is described here. During the time interval T1, the first satellite SAT_X transmits DATA_T1 data to a UE terminal. In this example, the SAT_X satellite moves away from the UE terminal, such that the UE terminal will soon be outside the CELL_X coverage area of ​​the SAT_X satellite. For this reason, an intercell handover must be initiated to switch the UE terminal to a third satellite SAT_Z. [YES] However, during the time interval T2, the UE terminal is not yet within the CELL_Z coverage area of ​​the third satellite, SAT_Z. Therefore, the first satellite, SAT_X, sends a COOP_QUERY request to the second satellite, SAT_Y, whose CELL_Y coverage area includes the UE terminal. The first satellite, SAT_X, sends Also, the second satellite, SAT_Y, receives the DATA_T2 data to be transmitted to the terminal. Following this, the second satellite, SAT_Y, sends the DATA_T2 data to the UE terminal.

[0112] During the T3 time interval, the CELL_Z coverage area of ​​the third satellite SAT_Z now includes the UE terminal, and the latter switches to the third satellite SAT_Z. Following this, the third satellite SAT_Z sends DATA_T3 data to at least one UE terminal.

[0113] In one embodiment, the switchover from the UE terminal to the third satellite SAT_Z is performed as follows: the ground station GW sends the DATA_T2 data to the first satellite SAT_X, to be transmitted to at least one UE terminal; this DATA_T2 data is transmitted to the UE terminal via the second satellite SAT_Y; then the ground station GW sends the DATA_T3 data to the third satellite SAT_Z, to be transmitted to the UE terminal. Thus, the ground station GW switches the data stream destined for the UE terminal from the first satellite SAT_X to the third satellite SAT_Z.

[0114] For example, the first SAT_X and the third SAT_Z satellites are assumed to be operated by the same operator, SNO_XZ, while the second SAT_Y satellite is operated by a different operator, SNO_Y. This implementation allows operator SNO_XZ to provide UE terminals with continuity of service, even though the coverage areas of its CELL_X and CELL_Z satellites are not continuous. This continuity of service is achieved through cooperation with the second SAT_Y satellite without using operator SNO_Y's terrestrial core network.

[0115] Figure 5 represents, in the form of a flowchart, the steps of a communication process according to one embodiment of the invention.

[0116] As illustrated by Figure 5, the communication system comprises, in one embodiment: a server SERVER; a network entity NE; a ground station GW; a first satellite SAT_X; a second satellite SAT_Y; and at least one terminal UE.

[0117] Figure 5 describes the steps implemented by the various elements of the communication system according to one embodiment and illustrates the temporal exchange of data between these elements. The following reference symbols allow, for each step of the process, the identification of the element implementing that step: References beginning with SS are used for steps implemented by the server SERVER; SN for the network entity NE; SG for the ground station GW; SX for the first satellite SAT_X; SY for the second satellite SAT_Y; SU for at least one terminal UE.

[0118] According to this embodiment, the SERVER is an application server that sends DATA to at least one UE terminal. For example, the SERVER could be a mobile phone server or a web server. According to this embodiment, The network entity NE is operated by a mobile network operator (MNO), while the ground station GW is operated by a satellite network operator (SNO). In another embodiment, for example in an edge application function context, the SERVER is an application server that sends DATA to at least one UE hosted in SAT_X.

[0119] During an SG10 step, the GW ground station receives AUTH resource delegation authorizations from the NE network entity (sent during an SN10 step). AUTH authorizations are sent, for example, by one or more mobile network operators (MNOs) and specify the spectrum and spots that can be used by satellites for cooperation.

[0120] During an SG20 step, the GW ground station sends COOP_AUTH cooperation authorizations (received during SX20 and SY20 steps) to the SAT_X and SAT_Y satellites. For example, a COOP_AUTH cooperation authorization allows the second satellite, SAT_Y, to cooperate with the first satellite, SAT_X.

[0121] During an SG30 step, the GW ground station receives CAP_SAT information from the SAT_X and SAT_Y satellites regarding the resources of the SAT_X and SAT_Y satellites (sent during SX30 and SY30 steps). For example, for a SAT_X satellite, the CAP_SAT information might indicate the frequency channels available for transmitting data in different cells.

[0122] During an SG40 step, the GW ground station receives REQ_FORE information from the NE entity relating to communication system specifications (sent during an SN40 step). For example, REQ_FORE information is issued by a mobile network operator (MNO) and corresponds to forecasts of the requirements for implementing a communication service, in terms of target throughput, probability of no coverage, and the number of connections required over a period of time.

[0123] During an SG50 step, the GW ground station determines COOP_DIM information regarding satellite resources that can be used for cooperation. In one embodiment, the COOP_DIM information corresponds to the number of free channels on the satellites, these free channels being available for cooperation. The determination of the COOP_DIM information by a CAP_COOP module of the GW ground station is detailed below with reference to Figure 6.

[0124] During an SG60 step, the GW ground station sends COOP_DIM information to the SAT_X and SAT_Y satellites regarding the number of channels, or more generally, available resources (received during SX60 and SY60 steps). For example, COOP_DIM information is sent to the SAT_X satellite indicating that the SAT_Y satellite has of a plurality of channels that can be used to transmit data within the CELL.

[0125] In one particular embodiment, the proposed process comprises several iterations of at least one of the steps SG40, SG50, and SG60. Thus, in this embodiment, the process includes updating the COOP_DIM information. This embodiment allows for regular updates of the COOP_DIM information, for example, based on new REQ_FORE requirements forecasts.

[0126] During an SX65 step, according to a particular embodiment, the first satellite SAT_X sends, audits at least one UE terminal, DATA_T1 data (received during an SU65 step).

[0127] During an SX70 step, according to a particular embodiment, the first satellite SAT_X receives, from at least one UE, BOOST information relating to a power level received by said UE (sent during an SU70 step). The BOOST information may, in particular, refer to a request to increase the power of the received signal, a power level of the received signal, or indicate that the power of the received signal is below a threshold, etc. For example, the BOOST information is a signal-to-interference-plus-noise ratio, more commonly referred to as SINR (Signal-to-Interference-plus-Noise Ratio), at the UE level for a signal received from the first satellite SAT_X.

[0128] During an SX80 step, the first satellite, SAT_X, determines a cooperation criterion, COOP_CRIT. This criterion determines whether the first satellite, SAT_X, initiates cooperation with the second satellite. Specifically, the first satellite, SAT_X, thus determines at the SX80 step whether cooperation is necessary.

[0129] A first example of the implementation of step SX80 is described here. Following the receipt of the BOOST information in step SX70, the first satellite SAT_X determines that cooperation is necessary and, based on the information relating to available resources COOP_DIM, sends a cooperation request COOP_QUERY to the second satellite SAT_Y.

[0130] In a second example, the first satellite, SAT_X, experiences a peak load over a given period. In this example, the first satellite, SAT_X, does not have sufficient frequency resources to transmit all the data to the terminals, and determines that cooperation is necessary.

[0131] More generally, the COOP_CRIT criterion can be determined by the first SAT_X satellite from at least one of the following pieces of information: a link budget between the first SAT_X satellite and the CELL cell; the trajectories of the SAT_X and SAT_Y satellites; the geographical coordinates defining the CELL cell.

[0132] During an SX90 step, based on the COOP_DIM information, the first satellite, SAT_X, sends a COOP_QUERY cooperation request (received during a SY90 step) to the second satellite, SAT_Y. The COOP_QUERY cooperation request is a request to transmit data to at least one UE terminal. In one embodiment, the COOP_QUERY cooperation request includes control data, for example, one or more of the following: channels to be used, cells, transmit power levels, transmit durations, and synchronization information. In particular, the synchronization information allows the SAT_X and SAT_Y satellites to coordinate their transmissions so that the signals transmitted by the satellites are received synchronously by a receiver.

[0133] During an SX100 step, according to a particular embodiment, the first satellite SAT_X receives a COOP_ACK response from the second satellite SAT_Y to the COOP_QUERY cooperation request (sent during a SY100 step). In one embodiment, the COOP_ACK response includes COOP_START information indicating that the SAT_Y satellite is available to cooperate, or COOP_STOP information indicating a period of unavailability.

[0134] During an SX110 step, the first satellite SAT_X receives DATA from the ground station GW (sent by the SERVER, the network entity NE, and the ground station GW respectively during SS110, SN110, and SG110 steps). The DATA is, for example, transmitted by the SERVER within the NET computer network.

[0135] During an SX120 step, the first satellite SAT_X sends COOP_DATA data to the second satellite SAT_Y to be transmitted to at least one UE terminal (received during a SY120 step).

[0136] During an SX130 step, according to one embodiment, the first satellite SAT_X sends DATA_X data (received during an SU130 step) to audit at least one UE terminal. The first satellite transmits the DATA_X data, for example, using a time-frequency block (CH1, T1). The DATA_X data may be different from or identical to the COOP_DATA data.

[0137] If the SX130 step is not implemented, then inter-satellite cooperation is of the relay type as previously described with reference to Figure 1. Otherwise, if the SX130 step is implemented, then inter-satellite cooperation is of the CoMP or carrier aggregation type as previously described with reference to Figures 2 and 3.

[0138] During a SY140 step, the second satellite SAT_Y sends, auditing at least one UE terminal, the COOP_DATA (received during a SU140 step). In one embodiment, the second satellite SAT_Y sends the COOP_DATA using a block time-frequency (CH1, Tl) identical to the time-frequency block used by the first satellite SAT_X to send the DATA_X data. According to another embodiment, the second satellite SAT_Y sends the COOP_DATA data using a different time-frequency block (CH2, Tl).

[0139] If, during the SY140 step, the second satellite SAT_Y uses a time-frequency block (CH1, Tl) identical to the time-frequency block used by the first satellite SAT_X, then the inter-satellite cooperation is of the CoMP type as previously described with reference to Figure 2. If, during the SY140 step, the second satellite SAT_Y uses a time-frequency block (CH2, Tl) different from the time-frequency block used by the first satellite SAT_X, then the inter-satellite cooperation is of the carrier aggregation type as previously described with reference to Figure 3.

[0140] In the embodiments described with reference to Figure 5, the cooperation entity according to the invention—determining the COOP_DIM information—is contained within the GW ground station. However, within the scope of the invention, other embodiments could be envisaged in which the cooperation entity is contained within any ground station, or a satellite management entity, or a geostationary satellite, etc. For example, one embodiment is described with reference to Figure 7 in which the cooperation entity is common to several MNOs and several SNOs.

[0141] Figure 6 schematically represents an example of information obtained and processed by a communication system according to an embodiment of the invention. In particular, Figure 6 illustrates the determination by the CAP_COOP module of the COOP_DIM information relating to available resources, which is then used by the SAT_X and SAT_Y satellites to implement inter-satellite cooperation.

[0142] According to one embodiment, the communication system processes the following information: CAP_SAT relating to satellite resources; REQ_FORE relating to the specifications of the communication system; and COOP_DIM relating to satellite resources that can be used for cooperation.

[0143] CAP_SAT information relates to the resources of one or more satellites for transmitting data within one or more cells. In one embodiment, for a given SAT satellite and CELL, CAP_SAT information includes one or more LIST_CH frequency bands that the satellite can use to transmit data within the cell. For example, as illustrated in Figure 6, the SAT_Y satellite can use channels CH_1 to CH_10 to transmit data, as part of one or more services provided by that satellite, to user equipment, such as terminals, located in CELL_A.

[0144] REQ_FORE information relates to the communication system specifications. According to an embodiment illustrated in Figure 6, for a given cell (CELL), the REQ_FORE information includes: a target communication rate (D) for its user equipment, a probability of non-coverage (P_OUT) for this equipment, and a number of connections (NB_USR). In addition, REQ_FORE information may include: signal strength levels received by this equipment; frequency bands; and geographic coordinates defining the cells. For example, REQ_FORE information is issued by one or more MNOs and describes specifications necessary to implement communication services. In this example, the REQ_FORE information corresponds to forecasts of the MNOs' needs.

[0145] COOP_DIM information relates to the resources of one or more satellites that can be used to transmit data in one or more cells. For a given SAT satellite and CELL, COOP_DIM information can indicate: a number of channels; a spectrum; and one or more frequency bands. These SAT satellite resources are free and can be used for cooperation. For example, as illustrated in Figure 6, the SAT_Y satellite has three free channels available for cooperation by transmitting data in the CELL_A cell.

[0146] According to an embodiment illustrated by Figure 6, the COOP_DIM information is determined by a CAP_COOP module of the GW ground station during an SG50 step from the CAP_SAT and REQ_FORE information.

[0147] A SAT satellite providing a communication service to equipment is considered here. In one embodiment, the COOP_DIM information for the SAT satellite is determined from a transmission rate D and a non-coverage probability P_OUT for the equipment related to the SAT satellite service. The COOP_DIM information can also be determined from a communication channel statistic between the satellite and a terminal. For example, the communication channel statistic between the satellite and equipment used to determine the COOP_DIM information is a standard deviation α, used as a parameter in a channel model to describe obstruction phenomena, as described below.

[0148] The determination of COOP_DIM information by the CAP_COOP module includes, according to one embodiment, at least one of the following steps.

[0149] During an SG51 step, the CAP_COOP module determines, for the given SAT satellite, the required usable bandwidth W_U to implement NB_USR connections with a data rate D and a probability of no coverage P_OUT between the satellite and the equipment. The data rate D, the probability P_OUT, and the number of NBR_USR connections can correspond to the specifications required by the SAT satellite service.

[0150] During an SG52 step, the CAP_COOP module determines, from the usable bandwidth W_U and a channel bandwidth W_CH, a number of usable channels NB_CH_U to implement the SAT satellite service.

[0151] During an SG53 step, the CAP_COOP module determines, from the number of usable channels NB_CH_U and the total number of channels NB_CH_TOT, a number of free channels NB_CH_COOP. These free channels are not, a priori, required for the implementation of the SAT satellite service. For this reason, the free channels can be used to implement inter-satellite cooperation.

[0152] More specifically, in the embodiment described here, the CAP_COOP module uses the following capacity formula during step SG51. For a satellite spot, the maximum capacity in number of simultaneous connections (i.e., NB_USR) is expressed as follows:

[0153] [Math. 1]

[0154] Or [Math. 2] c = au' • Q~ 1 (1 — Pout ) + am '

[0155] And [Math. 3]

[0156] And [Math. 4]

[0157] And [Math. 5] a 2 cr 2 = log((exp(a 2 o' 2 ) — 1)F + 1) + a 2 has 2

[0158] And [Math. 6]

[0159] For this expression of capacity, the following parameters are used: F, a form factor relative to the satellites of the communication system; n, the total number of satellites. or satellite beams (i.e., "spot"); P, a transmission power of the satellites; K, a propagation factor that is a function of the transmission frequency; W, a bandwidth; D, a transmission rate required for each connection; N B , a number of interfering spots; a, a standard deviation of the shadowing; N th , thermal noise; dj, a distance between the satellite j and the receiving equipment; P out , a probability of non-coverage; and has a constant, for example, equal to - 0.23. Thus, the CAP_COOP module determines the COOP_DIM information from all or part of the parameters mentioned above.

[0160] According to this embodiment, the capacity formula above is used by the CAP_COOP module to determine a useful bandwidth W_U (W in [Math. 1]) required to implement NB_USR connections (C in [Math. 1]) with a throughput D (£ in [Math. 1]) and a non-coverage probability P_OUT (P out in [Math. 1]).

[0161] The other parameters of the formula above are parameters defined by the CAP_COOP module.

[0162] In one embodiment, the CAP_COOP module performs multiple iterations of the steps described above. In a particular embodiment, at each iteration, the implementation module adjusts the throughput D by a coefficient a and updates the COOP_DIM information. The adjusted throughput aD, for example 95% of D, is referred to as degraded throughput. The consolidation loop thus implemented by the CAP_COOP module makes it possible to take into account and optimize the resources of the constellations and the demands of the MNOs.

[0163] Figure 7 shows, in flowchart form, the steps of a communication method according to an embodiment of the invention. In particular, this embodiment illustrates a communication system in which the SAT_X and SAT_Y satellites belong to different constellations. This embodiment can be combined with the embodiments described previously, in particular those described by reference in Figures 1 to 3. This embodiment thus makes it possible to implement inter-satellite cooperation of the relay, CoMP, or carrier aggregation type between satellites belonging to different constellations.

[0164] Compared to Figure 5, the communication system comprises, according to the embodiment illustrated by Figure 7: two network entities NE_X and NE_Y; one cooperation entity BROKER; two ground stations GW_X and GW_Y.

[0165] For example, this embodiment describes cooperation between several mobile network operators (MNOs) and several satellite network operators (SNOs). In this embodiment, the cooperation is implemented, in particular, by the BROKER entity, which may be common to several MNOs and several SNOs. The BROKER entity may be centralized or decentralized. In particular, the BROKER entity is configured to determine the TJ COOP_DIM information relating to satellite resources that can be used for cooperation.

[0166] During steps SB10 and SB11, the BROKER cooperation entity receives AUTH resource delegation authorizations (sent during steps SN10 and SN11) from the network entities NE_X and NE_Y. These AUTH authorizations are sent, for example, by one or more mobile network operators (MNOs) and specify the spectrum and spots that can be used by the satellites for cooperation.

[0167] During the SB20 and SB21 stages, the BROKER cooperation entity sends the COOP_AUTH cooperation authorizations (received by the GW_X and GW_Y ground stations during the SG20 and SG21 stages and then received by the SAT_X and SAT_Y satellites during the SX20 and SY21 stages) to the SAT_X and SAT_Y satellites via the GW_X and GW_Y ground stations.

[0168] During the SB30 and SB31 stages, the BROKER cooperation entity receives CAP_SAT information from the SAT_X and SAT_Y satellites via the GW_X and GW_Y ground stations (sent by the SAT_X and SAT_Y satellites during the SX30 and SY31 stages and then by the GW_X and GW_Y ground stations during the SG30 and SG31 stages).

[0169] During steps SB40 and SB41, the BROKER cooperation entity receives REQ_FORE information from network entities NE_X and NE_Y (sent during steps SN40 and SN41).

[0170] During an SB50 step, the BROKER cooperation entity determines the COOP_DIM information, this step being detailed below.

[0171] In the embodiment described here, during steps SB60 and SB61, the cooperation entity BROKER sends the COOP_DIM information to the SAT_X and SAT_Y satellites via the GW_X and GW_Y ground stations (received by the GW_X and GW_Y ground stations during steps SG60 and SG61 and then received by the SAT_X and SAT_Y satellites during steps SX60 and SY61).

[0172] Based on the COOP_DIM information and / or AUTH authorizations received, the SAT_X and SAT_Y satellites will be able to establish inter-satellite cooperation.

[0173] In this embodiment, the operators MNO_X and MNO_Y can implement different communication services with distinct specifications. Thus, according to one embodiment, the COOP_DIM information is determined from a plurality of transmission rates D_X and D_Y and a plurality of non-coverage probabilities POUT_X and POUT_Y relating to a plurality of communication services implemented by the communication system SYS.

[0174] As an example, two communication services with D speeds t and D2 and the probabilities of non-coverage P out | and P out2 are considered. Then, in this case, the CAP_COOP module uses an expression of the communication system capacity for a spot:

[0175] [Math. 7]

[0177] with a ± + a2 = 1 and c lr c2 respectively function of P out | , P out2in accordance with the expression [Math. 2].

[0178] Figure 8 represents, in the form of a flowchart, the steps of a communication process according to one embodiment of the invention.

[0179] According to an embodiment illustrated in Figure 8, the communication system implements a method for tracking resource usage to communicate with said at least one UE terminal. This embodiment notably enables reliable and precise traceability of the resources used during inter-satellite cooperation to communicate data to a terminal.

[0180] According to this embodiment, the SYS communication system includes at least one resource usage monitoring entity. For example, this monitoring entity is considered to be included in the network entity NE of the SYS system. However, it should be noted that this example is not limiting, and other embodiments could be considered in which this monitoring entity is included in each element of the SYS system. In particular, the SYS communication system may include a plurality of monitoring entities. In one embodiment, the SYS system includes: a first monitoring entity included in the network entity NE operated by a mobile network operator (MNO); and a second monitoring entity included in a ground station GW operated by a satellite network operator (SNO).

[0181] Compared to Figure 5, the process according to this embodiment further includes at least one of the steps described below.

[0182] During an SG10 step, the GW ground station receives, from a certified NE entity, one or more TDD resource delegation authorizations comprising respectively a public key associated with the certified NE network entity (sent during an SN10 step).

[0183] During an SG20 step, the GW ground station sends the TDD_X and TDD_Y authorizations to the SAT_X and SAT_Y satellites (received during SX20 and SY20 steps). For example, a TDD authorization can be issued by a mobile network operator (MNO) that owns a certain frequency spectrum. In this example, a mobile operator (MNO) authorizes a satellite operator (SNO) to use all or part of the spectrum held by the MNO to communicate data to UE terminals.

[0184] During an SG40 step, the GW ground station receives, from the NE certified entity, one or more TDU resource usage authorizations comprising respectively a signature determined from a private key associated with the NE certified entity (sent during an SN40 step).

[0185] During an SG60 step, the ground station GW sends the TDU_X and TDU_Y authorizations to the SAT_X and SAT_Y satellites (received during the SX60 and SY60 steps). For example, a TDU authorization can be issued by a mobile network operator (MNO) and specify the usable frequency spectrum. In this example, an MNO can authorize, via a TDU_X_W1 authorization, the first SAT_X satellite to use a frequency channel between 3.510 GHz and 3.529 GHz to communicate with terminals.

[0186] In one embodiment, a message signature is obtained by encrypting a hash of the message with the private key. Thus, upon receiving the message, the recipient simply decrypts the message signature with the sender's public key, and then compares the decrypted signature to a hash of the received message to verify its authenticity and integrity.

[0187] The SAT_X and SAT_Y satellites perform an SX61 and SY61 authentication step, respectively, for TDU spectrum usage authorizations based on received signatures and public keys. This implementation enables reliable and secure control of resource use, particularly during inter-satellite cooperation.

[0188] During an SX90 step, the first satellite SAT_X sends the following to the second satellite SAT_Y: a COOP_QUERY cooperation request; TUCP_X information; and TDU_X authorization (received during a SY90 step). The TUCP_X information indicates, for example, the number of time-frequency blocks used by the first satellite SAT_X to transmit the COOP_QUERY request; and the TDU_X authorization is used to indicate the spectrum being used.

[0189] During an SX100 step, according to a particular embodiment, the first satellite SAT_X receives from the second satellite SAT_Y: a COOP_ACK reply; TUCP_Y information; and TDU_Y authorization (sent during a SY100 step). For example, the TUCP_Y information indicates the number of time-frequency blocks used by the second satellite SAT_Y to transmit the COOP_ACK reply; and the TDU_Y authorization is used to indicate the spectrum being used.

[0190] During an SX120 step, the first satellite SAT_X sends the second satellite SAT_Y: COOP_DATA data; and TUDP_X information (received during a SY120 step). For example, the TUDP_X information indicates the number of time-frequency blocks used by the first satellite SAT_X to transmit the COOP_DATA data.

[0191] During an SX130 step, in one embodiment, the first satellite SAT_X sends the following to at least one UE terminal: DATA_X data; TDD_X and TDU_X authorizations; and TUDP_X information (received during a SU130 step). For example, the TUDP_X information indicates the number of time-frequency blocks used by the first satellite SAT_X to send the COOP_DATA and DATA_X data; and the TDD_X and TDU_X authorizations allow the receiver to authenticate the transmitted information and identify the resources used by the first satellite SAT_X.

[0192] During a SY140 step, the second satellite SAT_Y sends the following to at least one UE: COOP_DATA; TDD_Y and TDU_Y authorizations; and TUCP_Y and TUDP_Y information (received during a SU140 step). For example, TUCP_Y and TUDP_Y indicate the number of time-frequency blocks used by the second satellite SAT_Y to send the COOP_ACK response and COOP_DATA; and TDD_Y and TDU_Y authorizations allow the receiver to authenticate the transmitted information and identify the resources used by the second satellite SAT_Y.

[0193] During a SY150 step, the second satellite SAT_Y sends a COOP_TICKET message to the first satellite SAT_X, containing: the authorizations TDD_Y and TDU_Y; and TUCP_Y and TUDP_Y information. For example, the TUCP_Y and TUDP_Y information indicates all or part of the resources used by the second satellite SAT_Y during the cooperation.

[0194] During an SX150 step, according to a particular embodiment, the first satellite SAT_X sends a COOP_TICKET message to the second tracking entity within the ground station GW. This message includes: the authorizations TDD_X, TDD_Y, TDU_X, and TDU_Y; and TUCP_X, TUCP_Y, TUDP_X, and TUDP_Y information (received and transmitted by the ground station GW during an SG150 step). In this way, the tracking entity NE is able to accurately track and account for the resources used by the first SAT_X and the second SAT_Y satellites to communicate data to at least one UE terminal.

[0195] During a SU160 step, after receiving DATA_X and COOP_DATA, at least one UE terminal sends a COOP_TICKET message to the first tracking entity within the NE network entity (received during an SN160 step). The COOP_TICKET message includes: TDD_X, TDD_Y, TDU_X, and TDU_Y authorizations; and TUCP_X, TUCP_Y, TUDP_X, and TUDP_Y information received from the SAT_X and SAT_Y satellites. In this way, the NE tracking entity is able to track the resources. used by satellites to communicate data to the terminal and to prove that a communication has actually taken place.

[0196] In the embodiments described with reference to Figure 8, the SAT_X and SAT_Y satellites belong to the same constellation. However, the method described above also applies to embodiments in which the cooperation entity is common to several satellite operators (SNOs) and / or several mobile operators (MNOs).

[0197] Figure 9 schematically represents an example of the software and hardware architecture of a communication system according to one embodiment of the invention.

[0198] As illustrated in Figure 9, in one embodiment, the GW ground station comprises at least one of the following modules: a COM_NET_GW communication module configured to communicate with the NET communication network; and a COM_GW_SAT communication module configured to communicate with at least one of the SAT_X, SAT_Y and SAT_Z satellites.

[0199] As illustrated in Figure 9, according to one embodiment, the SAT_X and SAT_Y satellites respectively comprise at least one of the following modules: a COM_GW_SAT communication module configured to communicate with the GW ground station; a COM_SAT_SAT communication module configured to communicate with at least one other satellite; and a plurality of COM_SAT_UE communication modules (i.e., a satellite spot communication module) configured to communicate with said at least one UE terminal.

[0200] As illustrated in Figure 9, according to one embodiment, a said UE terminal comprises at least one of the following modules: a COM_SAT_UE communication module configured to communicate with at least SAT_X and SAT_Y satellites; and a COM_UE_NET communication module configured to communicate with the network.

[0201] In one embodiment, one or more elements of the SYS communication system have the hardware architecture of a computer. Consider an ELT element of the SYS communication system. In this embodiment, the ELT element comprises a PROC processor, RAM, MEM read-only memory, and non-volatile memory. The MEM memory constitutes a computer-readable information storage medium according to the invention, on which a computer program is stored. The computer program contains instructions for implementing the steps carried out by the ELT element of a process according to the invention when the computer program is executed by the PROC processor. The computer program defines the functional modules shown below in Figure 10, which rely on or control the hardware elements of the latter.

[0202] Figure 10 schematically represents an example of the functional architecture of a communication system according to one embodiment of the invention.

[0203] The following reference signs allow, for each of the communication system modules, the identification of the element comprising that module: References beginning with MG are used for the modules of the GW ground station; MX for the first satellite SAT_X; MY for the second satellite SAT_Y; MU for said at least one UE terminal.

[0204] As illustrated in Figure 10, in one embodiment, the GW ground station comprises at least one of the following modules: an MG_CAP_COOP determination module to determine the COOP_DIM information; an MG_SND_DIM sending module to send the COOP_DIM information; and an MG_SND_DATA sending module to send the DATA data.

[0205] As illustrated in Figure 10, according to one embodiment, the first satellite SAT_X comprises at least one of the following modules: an MX_RCV_DIM receiving module to receive the COOP_DIM information; an MX_DET_CRIT determining module to determine the COOP_CRIT criterion; an MX_SND_COOP sending module to send the COOP_DATA data; an MX_SND_QUERY sending module to send the COOP_QUERY request; an MX_RCV_ACK sending module to receive the COOP_ACK response; an MX_RCV_DATA receiving module to receive the DATA data; an MX_SND_DATA sending module to send the DATA_X data; an MX_RCV_BOOST receiving module to receive the BOOST information.

[0206] As illustrated in Figure 10, according to one embodiment, the second satellite SAT_Y comprises at least one of the following modules: a MY_RCV_QUERY receiving module to receive the COOP_QUERY request; a MY_SND_ACK sending module to send the COOP_ACK response; a MY_RCV_COOP receiving module to receive the COOP_DATA data; and a MY_SND_COOP sending module to send the COOP_DATA data.

[0207] As illustrated in Figure 10, according to one embodiment, a said terminal UE comprises at least one of the following modules: a receive module MU_RCV_DATA to receive DATA_X and / or COOP_DATA data; and a send module MU_SND_BOOST to send BOOST information.

[0208] The term module can refer to a software component, a hardware component, or a set of hardware and software components. corresponding itself to one or more computer programs or subprograms, or more generally to any element of a program capable of implementing a function or set of functions as described for the modules concerned. Similarly, a hardware component corresponds to any element of a hardware assembly capable of implementing a function or set of functions for the module concerned (integrated circuit, smart card, memory card, etc.).

[0209] It should be noted that the order in which the steps of a process as described above are carried out, particularly with reference to the accompanying drawings, is merely an example of an embodiment and is not intended to be limiting; variations are possible. Furthermore, the reference symbols are not intended to limit the scope of protection; their sole purpose is to facilitate understanding of the claims.

[0210] A person skilled in the art will understand that the embodiments and variations described above are merely non-limiting examples of how the invention can be implemented. In particular, a person skilled in the art may consider any adaptation or combination of the embodiments and variations described above to meet a specific need.

Claims

Claims

1. Method implemented by a first air or space device (SAT_X) for transmitting data to at least one terminal (UE), the method comprising: receiving (SX60), from a cooperation entity (GW, BROKER), information (COOP_DIM) relating to resources of at least one second air or space device (SAT_Y) that can be used to transmit data to said at least one terminal (UE); if a cooperation criterion (COOP_CRIT) is verified, triggering cooperation with said at least one second device (SAT_Y) as a function of said information (COOP_DIM) to transmit data to said at least one terminal (UE), said cooperation comprising: sending (SX120), to said at least one second device (SAT_Y), second data (COOP_DATA) to be transmitted to said at least one terminal (UE).

2. Method according to claim 1 comprising sending (SX90), to said at least one second device (SAT_Y), a cooperation request (COOP_QUERY) for transmitting data to said at least one terminal (UE), said cooperation request (COOP_QUERY) comprising control data for the implementation of said cooperation.

3. Method according to claim 1 or 2, wherein said information (COOP_DIM) relating to the resources of said at least one second device (SAT_Y) which can be used is updated by said cooperation entity (GW, BROKER).

4. Method according to one of claims 1 to 3 comprising sending (SX130), to said at least one terminal (UE), first data (DATA_X) using a time-frequency resource (CH1,T1) used by said at least one second device (SAT_X) to transmit the second data (COOP_DATA) to said at least one terminal (UE).

5. Method according to one of claims 1 to 4 comprising sending (SX130), to said at least one terminal (UE), first data (DATA_X) using a time-frequency resource (CH1,T1) different from a time-frequency resource used (CH2,T1) by said at least one second device (SAT_X) to transmit the second data (COOP_DATA) to said at least one terminal (UE).

6. Method according to one of claims 1 to 5 in which the first (SAT_X) and said at least one second device (SAT_Y) belong to the same constellation.

7. Method according to one of claims 1 to 5 in which the first (SAT_X) and said at least one second (SAT_Y) devices belong to different constellations.

8. Method according to one of claims 1 to 7 comprising a reception (SX70) of information (BOOST) by said at least one terminal (UE), said cooperation criterion (COOP_CRIT) being determined (SX80) from this information (BOOST).

9. Method implemented by a cooperation entity (GW, BROKER) for communicating with a first aerial or space device (SAT_X), the method comprising: a determination (SG50, SB50) of information (COOP_DIM) relating to resources of at least one second aerial or space device (SAT_Y) which can be used to transmit data to at least one terminal (UE); a sending (SG60, SB60), to the first device (SAT_X), of said information (COOP_DIM).

10. Method according to claim 9 wherein said information (COOP_DIM) relating to the resources of said at least one second device (SAT_Y) which can be used is determined from at least one target data transmission rate (D) and at least one probability of non-coverage (P_OUT) defined for at least one communication service implemented by the second device.

11. Method according to claim 10 comprising one or more iterations of an update of said information (COOP_DIM) relating to the resources of said at least one second device (SAT_Y) which can be used from at least one adjusted flow rate, said at least one adjusted flow rate being obtained from said at least one target flow rate and a coefficient.

12. Method according to one of claims 9 to 11, the method comprising: sending, to the first device (SAT_X), data (DATA_T2) to be transmitted to said at least one terminal (UE), these data (DATA_T2) being transmitted to said at least one terminal (UE) via said at least one second device (SAT_Y); then a sending, to a third air or space device (SAT_Z), of data (DATA_T3) to be transmitted to said at least one terminal (UE).

13. Air or space device, called first device (SAT_X), adapted to transmit data to at least one terminal (UE), said first device (SAT_X) comprising: a reception module (MX_RCV_DIM) configured to receive, from a cooperation entity (GW, BROKER), information (COOP_DIM) relating to resources of at least one second air or space device (SAT_Y) which can be used to transmit data to said at least one terminal (UE);a sending module (MX_SND_COOP) configured to, if a cooperation criterion (COOP_CRrr) is verified, trigger a cooperation with said at least one second device (SAT_Y) as a function of said information (COOP_DIM) to transmit data to said at least one terminal (UE), said cooperation comprising a sending (SX120) by the sending module (MX_SND_COOP) to said at least one second device (SAT_Y) of second data (COOP_DATA) to be transmitted to said at least one terminal (UE).;

14. Cooperation entity (GW, BROKER) adapted to communicate with a first aerial or space device (SAT_X), the cooperation entity (GW) comprising: a determination module (MG_CAP_COOP) configured to determine information (COOP_DIM) relating to resources of at least one second aerial or space device (SAT_Y) which can be used to transmit data to at least one terminal (UE); a sending module (MG_SND_DIM) configured to send said information (COOP_DIM) to the first device (SAT_X).

15. System (SYS) comprising: a first air or space device (SAT_X) according to claim 13; at least one second air or space device (SAT_Y) comprising a reception module (MY_RCV_COOP) configured to receive, from the first device (SAT_X), second data (COOP_DATA) and a sending module (MY_SND_COOP) configured to send, to at least one terminal (UE), the second data (COOP_DATA) a cooperation entity (GW, BROKER) according to claim 14; and at least one terminal (UE) comprising a reception module (MU_RCV_DATA) configured to receive, from said at least one second device (SAT_Y), second data (COOP_DATA).

Images