EP3794747A1

EP3794747A1 - Method for managing the telecommunication data traffic of a very high throughput satellite communication system

Info

Publication number: EP3794747A1
Application number: EP19712181.7A
Authority: EP
Inventors: Cédric Baudoin; Sandra VIME; Bertrand ONILLON
Original assignee: Thales SA
Current assignee: Thales SA
Priority date: 2018-05-17
Filing date: 2019-03-19
Publication date: 2021-03-24
Also published as: US11336365B2; WO2019219275A1; US20210194574A1; CA3100097A1

Abstract

A method for managing the telecommunication data traffic of a very high throughput satellite communication system in which, for each satellite, management of a diversity of sites referred to as n+p sites and/or load diversity is implemented in a digital transparent processor in the satellite, in order to ensure the availability of the very high throughput communication system.

Description

Method for managing the telecommunication data traffic of a very high speed satellite communication system

The invention relates to a method for managing the telecommunication data traffic of a very high speed satellite communication system.

The very high-speed satellite systems, or VHTS for "Very High Throughput Satellites" in English, are characterized by very high capacities. In order to limit the number of gateways in English, the use of the Q / V band or a higher frequency band such as the W or Ka band is a major element. If they significantly increase the band by GW, these very high bands imply the implementation of mechanisms of spatial diversity in order to fight against the very important attenuations in these bands.

Diversity techniques should limit the impact on the system as much as possible (whether it is the duration of interruption or the decrease in capacity) while having the least cost.

It is notably known a strategy managing the spatial or geographical diversity, and a strategy managing the load diversity. The strategy of spatial or geographical diversity is based on the assumption that the spatial correlation of rainfall events decreases very strongly if we consider a distance between two sites of a few kilometers (typically 15 to 50 km). In other words, it is very unlikely to have heavy rain at the same time at two sites spaced by such a distance. For a light rain, it is between 200 and 1000 km, and for a storm 10 km. It is then possible to use one or more redundancy sites so that they support the feeder link between a ground station and a satellite when a station on the ground and in the rain. This spatial diversity strategy can take different forms depending on the type of redundancy chosen and its mode of realization. The diversity or load-sharing strategy is based on the principle that a user spot (geographical area on the surface of the earth) is served simultaneously by several baseband gateways or hubs in the English language. When one of the hubs suffers too much attenuation, all the terminals managed by the hub is switched to the other hubs serving these spots. This load sharing can be achieved by time or frequency multiplexing of the spectral resource. Finally, this technique can be performed either by assuming a loss of capacity of the system during the rain event or by allowing to maintain the system capacity (at the price of a greater number of hubs).

The diversity of charge sharing (called "smart diversity" in English) is for example illustrated in the documents:

- "Concept of technology for a Terabit / s satellite supporting future broadband services via satellite", by Paul Thompson, Barry Evans, Laurent Castanet, Michel Bousquet, Takis Mathiopoulos, SPACOMM 2011: The Third International Conference on Advances in Satellite and Space Communications;

- "Smart gateways for satellite satellites" by Nicolas Jeannin, Laurent Castanet, José Radzik, Michel Bousquet, Barry Evans, Paul Thompson, International Journal of Satellite Communications and Networking, vol. 32 (No. 2). pp. 93-106. ISSN 1542-0973; and

- "Smart Gateways Concepts for High-Capacity Multi-Beam Networks", by Riccardo De Gaudenzi, Emiliano Re, Piero Angeletti, 30th AIAA International Communications System Conference (ICSSC), September 24-27, 2012 Ottawa Canada.

Concerning the spatial diversity strategy, two techniques are mainly known, the RF station redundancy and the diversity of n + p sites.

The diversity of sites n + p is for example described in the documents: - "Gateway Diversity Scheme for a Future Broadband Satellite System", by Argyrios Kyrgiazos, Barry Evans, Paul Thompson, and Jean Jeannin, 2012 6th Advanced Satellite Multimedia Systems Conference (ASMS) and 12th Signal Processing for Space Communications Workshop (SPSC); and

- "Smart gateways for satellite satellites" by Nicolas Jeannin, Laurent Castanet, José Radzik, Michel Bousquet, Barry Evans, Paul Thompson, International Journal of Satellite Communications and Networking, vol. 32 (No. 2) p 93-106. ISSN 1542-0973.

RF redundancy, as illustrated in the example of Figure 1, consists of having for each hub 1 two RF ground stations 2, 3 sufficiently distant to decorrelate the rain events (at least 15 km, and typically 50 km). The corresponding RF gateway 4 or gateway in English language is also represented. This technique also meets the requirement of system availability. It is also relatively simple to implement since it has no impact on the high layers and does not require specific switching on board. It nevertheless requires a strong synchronization of the two RF paths, obtained by pre-compensation techniques. However, it appears relatively expensive in terms of connection cost in order to interconnect the two sites (n times), and of number of RF stations which are doubled, which significantly increases the operating expenses or OPEX and the expenses of investment or CAPEX of the ground segment.

The diversity of n + p sites, as illustrated in the example of Figure 2, can be presented as the reference redundancy scheme for very high speed systems called THD systems. The principle consists of having redundancy sites redundant to p sites simultaneously among the n nominal sites. This technique is extremely efficient in terms of availability, making it possible to reach availability significantly higher than the requirement (typically 99.9%) with a very small number of hubs (1 to 3 for systems with a few dozen hubs). This solution involves a hand-over of the hub (the redundant hub 5 can be considered as a clone of the nominal hub 6) and a rerouting of the traffic to the hub. redundant 5 (network failover). In this sense, this diversity scheme is similar to hot redundancy techniques, with the difference that the decision takes into account the level of attenuation. At the payload level, the switching from one hub 6 to another 5 is generally performed by electromechanical switches or switches, which leads to interruptions of service of several seconds.

This solution has a higher cost but without loss of capacity in case of rain.

The diversity of n + p sites is for example described in the documents "Gateway diversity scheme for a future broadband satellite system" (Nicolas Jeannin, Argyrios Kyrgiazos, Barry Evans, Paul Thompson, 2012 6th Advanced Satellite Multimedia Systems Conference (ASMS) and 12th Signal Processing for Space Communications), and "Smart gateways for satellite satellites" (Nicolas Jeannin, Laurent Castanet, José Radzik, Michel Bousquet, Paul Evans, Paul Thompson, International Journal of Satellite, Communications and Networking, Vol 32 (no. 2), pp. 93-106, ISSN 1542-0973).

With respect to load-sharing diversity, a conventional solution, as illustrated in FIG. 3, is to manage a spot by means of several hubs simultaneously, each of them supporting a frequency sub-band. the frequency band of the spot. The objective is to be able to have the capacity provided by the hubs that are not in the rain, to ensure the service of the users of a hub that has an attenuation exceeding its power margin. This solution is also called "smart diversity" in English or diversity n + 0, since no additional hub is needed. This technique has the main advantage of not requiring an additional hub (and the associated interconnection) to achieve system availability. This scheme, however, involves a more complex payload to separate and recombine the different subbands per spot. In addition, it implies a capacity loss of 1 / n if a hub experiences an attenuation greater than its power margin, 2 / n if two hubs are unavailable simultaneously. (with a lower probability), etc .... Finally, this mechanism requires to perform a transfer ("hand-over" in English) users that the hub can no longer serve due to too much attenuation. These must then be supported (without sewing, ie without interruption of traffic) by the different hubs in charge of the spots concerned which are not in this situation.

This solution has a reduced cost, but with a loss of capacity in case of rain.

An object of the invention is to overcome the problems mentioned above, especially in case of rain, at reduced cost, to limit the loss of capacity. According to one aspect of the invention, there is provided a method for managing the telecommunication data traffic of a very high-speed satellite communication system in which, for each satellite, it is implemented in a digital processor. transparent (DTP) in the satellite, managing a variety of so-called n + p sites and / or load diversity to guarantee the availability of the very high speed communication system.

Such a method avoids impacts on the payload, and does not add RF strings to handle additional RF gateways for diversity. It also avoids the need for additional footbridges on the ground. This method is also generic and benefits from the functions offered by the transparent digital processor DTP (flexible RF connectivity in the satellite). Finally, this method allows a fast reconfiguration in case of hub transfer and with very low losses at the satellite level (compared to solutions based on embedded switches). In one implementation mode, it implements in the transparent digital processor the management of transitions between the so-called n + p site diversity and / or the load diversity.

By transition between the two diversities is meant a transition from one to the other regardless of the meaning.

Thus, it is possible to adapt the implemented diversity solution according to the required availability, the number of available sites, or the constraints of the payload (for example number of RF channels processing the RF gateways).

According to one embodiment, a so-called n + p site diversity is implemented by the transparent digital processor, by switching from a nominal site to a diversity site, by rerouting the input ports of the nominal site. switched to said diversity site, whose output ports are those of the nominal site switched.

Thus, it is possible to offer a very high availability while being transparent for the end users.

In a mode of an implementation mode, a load-sharing diversity for serving a user spot by several sites is implemented by the transparent digital processor by cutting the frequency bandwidth into frequency sub-bands. and allocating these subbands to any set of output ports to multiplex them frequently on the one hand to the same site for the forward channel and on the other hand to different sites for the return channel.

Thus, it avoids the additional RF gateways necessary for N + p diversity, as well as the payload impacts (no addition of RF channels to handle additional RF gateways for diversity, no switching edge). According to one implementation mode, transitions of diversity are implemented in the transparent digital processor of the satellite so that:

during a first period of implementation of the system, a variety of so-called n + p sites or a load sharing diversity is implemented, a site corresponding to a gateway / hub / antenna assembly, p representing the number of sites; of diversity that can simultaneously redundant the n nominal sites in diversity of sites;

during a second period of scaling up of the system, a diversity of sites is implemented when the first period implements a load sharing diversity or maintained when the first period already implements a diversity of sites, and Nominal sites are added and n increases; and

during a third full load period of the system, a load sharing diversity is implemented, and the p diversity sites are used as nominal sites.

Such a method allows in case of rain, at reduced cost, to have no loss of capacity.

In one embodiment, p is initially 1 or 2.

According to one embodiment, a transition is made from the first period to the second period when the bandwidth managed by the initial nominal sites deployed during the first period is less than the total bandwidth required to serve all the terminals. using the communication system.

The total bandwidth is a functional feature of the system: if at the beginning we have deployed two GW gateways each managing 12 GHz bandwidth, if the need for the terminals becomes greater than 24 GHz bandwidth, then we must deploy a gateway GW extra, and this is done before system saturation. In one mode of implementation, a transition is made from the second period to the third period when the number of nominal sites is equal to the number of on-board reception channels on board the satellites of the very high speed communication system.

Thus, it is not necessary to deploy new sites or gateways to manage diversity, while ensuring the availability of gateway-satellite links.

It is also proposed, according to another aspect of the invention, a very high speed satellite communication system comprising means for managing the operation of the telecommunication data traffic comprising a transparent digital satellite processor for implementing the method. as previously described.

The invention will be better understood by studying a few embodiments described by way of non-limiting examples and illustrated by the appended drawings in which:

FIG. 1 diagrammatically represents a method for managing telecommunication data traffic of a very high-speed satellite communication system with RF redundancy, according to the state of the art;

FIG. 2 diagrammatically illustrates a method of managing the telecommunication data traffic of a very high-speed satellite communication system with so-called n + p site diversity, according to the state of the art;

FIG. 3 schematically illustrates a method of managing the telecommunication data traffic of a very high-speed satellite communication system with load sharing, according to the state of the art;

FIG. 4 schematically illustrates a transparent digital processor (DTP)

FIG. 5 diagrammatically represents a method for managing the telecommunication data traffic of a data communication system. very high speed satellite communication according to one aspect of the invention; and

FIGS. 6 and 7 represent a system for managing the telecommunication data traffic of a very high-speed satellite communication system, respectively for the forward payload and the return payload, according to one aspect of the invention. invention.

In all the figures, the elements having identical references are similar.

The present invention relates to a method for managing the telecommunication data traffic of a very high-speed satellite communication system in which, for each satellite, a DTP transparent digital processor is implemented in the satellite. managing a variety of so-called n + p sites and / or a load diversity to guarantee the availability of the very high speed communication system.

The transparent digital processor DTP is used to manage transitions between the so-called n + p site diversity and the load diversity.

A so-called n + p site diversity is implemented by the transparent digital processor DTP, by switching from a nominal site to a diversity site, by rerouting the input ports of the nominal site switched to said site. diversity site, whose output ports are those of the nominal site switched.

A load-sharing diversity for serving a multi-site user spot is implemented by the DTP transparent digital processor by splitting the rising frequency bandwidth into frequency sub-bands, and allocating them. sub-bands to any set of output ports to multiplex them frequently on the one hand to the same site for the forward channel and on the other hand to different sites for the return channel. Figure 4 shows a transparent digital processor or DTP present in each satellite.

The signals of the RFinput input ports (from the antennas) are respectively scanned and filtered by the ADC acronym digitizing function for the English-language "Analogie Digital Converter" of the RX receiver module.

The digitized samples thus obtained are then amplified by the gain function of the reception module RX.

The digitized and amplified signals are then demultiplexed by the Demux demultiplexing function of the reception module RX, to be transmitted to the port of the connectivity switching matrix of the DTP, for example if the frequency band coming from an RFinput input port is greater than the input frequency band of the connectivity switching matrix of the DTP then it needs to be separated into several sub-frequency bands.

The connectivity switching matrix then makes it possible to connect any sub-frequency band of an RFinput input port to any frequency sub-band of the same size as a RFoutput output port.

The switching matrix Connectivity thus provides the function of switching and transposing frequencies.

The digital signals at the output of the connectivity switching matrix are then multiplexed by the multiplexing function Mux of the TX transmission module to be adapted to the frequency bands of the output RFoutput ports.

Digital samples are then amplified by the function

Gain Tx. The amplified digital samples are then converted into analog signals by the digital-to-analog conversion function DAC for the acronym "Digital to Analogie Converter" in English and transmitted to the RFoutput (amplification and antenna) output ports.

The Clock function is in charge of the fine synchronization of the DTP which is required on the one hand for the dating of the configuration commands and on the other hand for the reconstruction of the analog signals from the scanned samples that have passed through the connectivity matrix. .

The Command & Control command and control function is in charge of the application of remotes from the ground and the sending of telemetries.

The configuration of the DTP is realized through the definition of the logical channels which are characterized by:

• an RFinput input port;

• an input frequency band;

• a RFoutput output port;

• an output frequency band (of the same size as the input frequency band but which can be transposed into frequencies).

For a given gateway, the configuration of the channels will consist of defining for each carrier or group of carriers from the GW gateway a logical channel to an output user spot for the forward channel, and vice versa in the return channel.

For the diversity of sites, the configuration of the DTP consists for the nominal sites to connect the different groups of carriers sent by a gateway GW with the different user spots for the forward channel and vice versa for the return channel.

Performing a nominal site switch n to a redundancy site p is performed by modifying the configuration of the logical channels of the gateway n to replace the input ports n by the input ports p (the frequency bands and transposition remaining identical).

For site diversity, configuration consists of defining logical channels to a given user spot from multiple gateways. For load-sharing diversity, for example three gateways for a spot, three channels are defined for a given user spot on the one-way, each of them coming from a different gateway (and therefore from a port of RFinput input of different DTP). The definition of the channels via the transposition in frequency band then makes it possible to multiplex the different carriers to the same user spot.

If, during the first period P1, a diversity of sites is implemented, the configuration P2 is modified during the second period P2 to add additional gateways, and thus add additional channels that can be switched to the different user spots.

If during the first period P1 a load sharing diversity is implemented, when changing to the second period P2, the configuration of the DTP is changed from a load sharing configuration to a site diversity configuration. taking into account the newly introduced gateways. Similarly, the configuration is changed during the transition from the second period P2 to the third period P3 to move from a site diversity configuration to a load sharing configuration. FIG. 5 schematically represents a method for managing telecommunication data traffic of a very high-speed satellite communication system, according to one aspect of the invention.

For each satellite, it implements, in the transparent digital processor (DTP): during a first system implementation period P1, a diversity of so-called n + p sites or a load-sharing diversity is implemented, a site corresponding to a gateway / concentrator / antenna set, p representing the number of sites; diversity sites that can simultaneously redundant the n nominal sites in diversity of sites;

during a second ramp up period P2 of the system, a diversity of sites is implemented when the first period P1 implements a load sharing diversity or maintained when the first period P1 already implements a diversity of sites. , and nominal sites are added and n increases; and

during a third period P3 of full load of the system, a load-sharing diversity is implemented, and the p diversity sites are used as nominal sites.

The present invention makes it possible to use two diversity techniques (n + p site diversity and load sharing), each in a moment when it is respectively the most suitable, and without adding equipment on board satellites or on the ground.

The advantages of the present invention are numerous:

- there is no payload impact in the English language (no addition of transponders or dedicated switching matrix),

- there is no impact on cost or payload performance,

- this is a generic solution that reuses the flexibility mechanisms offered by the DTP transparent digital processors, there is no loss of capacity during the rain events during the period P2 and possibly the period P1 when the diversity of sites is implemented during this period, until the last one or two GW gateways are deployed, and

- site redundancy is managed by a reconfiguration of the transparent digital processors DTP, which is very fast (compared to an electromechanical switching solution) or "switch guide" in English) and has a very short interruption time.

Thus, the present invention has the advantages of n + p site diversity and charge sharing techniques while limiting their respective disadvantages.

We switch from the first period P1 to the second period P2 when the sites (or gateways) initially deployed are no longer able to send and receive the bandwidth needed to manage the traffic. New sites (or gateways) are then deployed to support the ramping up of traffic.

We switch from the second period P2 to the third period P3 when the number of nominal sites (or nominal gateways) deployed is equal to the number of sites (or gateways) supported by the system determined by satellite design.

The principle of the invention is to manage the diversity for the high frequency bands (typically Q / V) by the transparent digital DTP processors of the satellites, and to combine the n + p site diversity and the load sharing diversity according to the system load so as not to introduce additional sites (on the ground) or antenna sources and associated RF chains (onboard satellites).

The n + p diversity is managed by modifying the channels of a DTP transparent digital processor on a specific date and synchronized with the ground segment (or Hub). Load-sharing diversity is managed through the flexibility and routing mechanisms offered by the transparent digital processors DTP (the carriers of two gateways are routed to the same spot).

FIGS. 6 and 7 show a system for managing the telecommunication data traffic of a very high-level communication system. satellite throughput, respectively for the forward payload and the return payload, according to one aspect of the invention.

Figure 6 shows the forward or "forward" channel in English on board the satellite. It has N + p sources antennas, which are then filtered, amplified and converted into frequency before being routed in the DTP.

During the first period P1, a variety of sites or load sharing is implemented in this case with 5 nominal gateways (n = 5) GW1, GW2, ..GW5.

The N-6 + 1 gateways GW6, GW7, ... GWN are not used during this first period P1 of implementation of the system.

During the second P2 period, the N-6 + 1 gateways GW6, GW7, ... GWN become one after the other of the nominal gateways, depending on the deployment of new GW gateways to ensure the scalability of the system ( new users are using this system and therefore require more tape).

The diversity gateways during the third period P3 the p gateways of diversities during the first and second periods P1 and P2 instantly become nominal gateways (n goes from N to N + p).

Figure 7 shows the return channel or "return" in English on board the satellite. It has N sources antennas, which are then filtered, amplified, re-filtered and converted into frequency before being routed in the DTP.

During the first period P1, a variety of sites or load sharing is implemented in this case with 5 nominal gateways (n = 5) GW1, GW2, ..GW5. The N-6 + 1 gateways GW6, GW7, ... GWN are not used during this first period P1 of implementation of the system.

During the second P2 period, the N-6 + 1 gateways GW6, GW7, ... GWN become one after the other of the nominal gateways, depending on the deployment of new GW gateways to ensure the scalability of the system ( new users are using this system and therefore require more tape). The diversity gateways during the third period P3 the p gateways of diversities during the first and second periods P1 and P2 instantly become nominal gateways (n goes from N to N + p).

If an operator wants the gateways during the third full system load period P3 to be different from those of the diversity sites, this only impacts the number of antenna sources and some switches or switches near the sources (with a very low impact ).

Claims

A method for managing the telecommunication data traffic of a very high-speed satellite communication system in which, for each satellite, a digital transparent processor (DTP) is implemented in the satellite. a diversity of so-called n + p sites and / or a load diversity to guarantee the availability of the very high speed communication system.

2. The method as claimed in claim 1, in which the management of transitions between the so-called n + p site diversity and the charge diversity is implemented in the transparent digital processor (DTP).

3. Method according to one of the preceding claims, wherein a variety of so-called n + p sites is implemented by the transparent digital processor (DTP), by switching from a nominal site to a diversity site, by rerouting input ports of the nominal site switched to said diversity site, whose output ports are those of the switched nominal site.

4. Method according to one of the preceding claims, wherein a charge sharing diversity for serving a user spot by several sites is implemented by the transparent digital processor (DTP) by cutting the rising frequency bandwidth into frequency sub-bands, and by allocating these subbands to any set of output ports to multiplex them frequently on the one hand to the same site for the forward channel and on the other hand to different sites for the return way.

5. Method according to one of the preceding claims, wherein is implemented in the transparent digital processor (DTP) of the satellite transitions of diversity so that:

during a first period (P1) of implementation of the system, a variety of so-called n + p sites or a load sharing diversity is implemented, a site corresponding to a set gateway / concentrator / antenna, p representing the number of diversity sites that can simultaneously redundant the n nominal sites in diversity of sites;

during a second period (P2) of scaling up the system, a diversity of sites is implemented when the first period (P1) implements a load sharing diversity or maintained when the first period (P1) already sets implement a diversity of sites, and nominal sites are added and n increases; and

during a third period (P3) of full load of the system, a load sharing diversity is implemented, and the p diversity sites are used as nominal sites.

The method of claim 5, wherein p is initially 1 or 2.

The method of claim 5 or 6, wherein a transition from the first period (P1) to the second period (P2) is performed when the bandwidth managed by the initial nominal sites deployed during the first period (P1) is less than the total bandwidth required to serve all terminals using the communication system.

8. Method according to one of claims 5 to 7, wherein a transition is made from the second period (P2) to the third period (P3) when the number of nominal sites is equal to the number of embedded site reception channels. onboard the satellites of the very high speed communication system.

9. Very high speed satellite communication system comprising means for managing the operation of the telecommunication data traffic comprising a transparent digital processor (DTP) by satellite for implementing the method according to one of the preceding claims.