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Doc. ID: TSTI2/HH/TN/18.23 Issue: 1 Date: 27/06/2018

Fuel

TAO (Towards the All Optical satellite communications system)

ESA Contract Nr. 4000117594/16/NL/GLC

Executive Summary

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This document may only be reproduced in whole or in part, or stored in a retrieval system, or transmitted in any form, or by any means electronic, mechanical, photocopying or otherwise, either with the prior permission of Airbus Defence & Space SAS or in accordance with the terms of ESA Contract No. 4000117594/16/NL/GLC.” Page 1

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Table of contents

Abstract ...... 7

1. Introduction ...... 9

2. State of the art ...... 11

3. Market analysis ...... 14

3.1 Space based communication systems ...... 14

3.2 Terrestrial communication systems ...... 15

4. Identification of scenarios ...... 19

4.1 Considered scenarios ...... 19

4.2 Selection of scenario ...... 19

4.3 Scenario A: provide connectivity in case of lack of terrestrial network ...... 20

4.4 Scenario B: provide redundancy in case of failure of terrestrial network ...... 21

5. Architecture & roadmap of an all optical satellite system ...... 23

5.1 On-board architecture ...... 23

5.2 On-ground architecture ...... 25

5.3 Roadmap for an all optical satellite system ...... 26

6. Conclusion ...... 28

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List of Figures

Figure 1 : TAO study logic ...... 9 Figure 2 : system configurations considered in the TAO study ...... 11 Figure 3 : Satellite technology evolution ...... 14 Figure 4 : Evolution of connected home devices ...... 16 Figure 5: Illustration of Scenario 2 - All optical backhauling of white areas ...... 21 Figure 6: Illustration of Scenario 1 - Redundancy of terrestrial network ...... 22 Figure 7: Difference between an optical amplifier and an optical repeater...... 23 Figure 8: architecture of an all optical satellite system with on-board processing (repeater option) and associated TRL level for a 100 Gbps optical link ...... 24 Figure 9: architecture of an all optical satellite system without on-board processing (amplifier option) ...... 25 Figure 10: Functional architecture of a ground station and corresponding TRL levels ...... 25

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List of Tables

Table 1 : synthesis on space based optical systems ...... 12 Table 2 : main mission characteristics ...... 13 Table 3 : Non-GEO Communications Constellations Projets, 2017-2021 ...... 15

Acronyms and abbreviations

Acronym Definition

Airbus DS Airbus Defence and Space AIT Assembly, Integration and Tests EDRS European Data Relay System GEO Geostationary Orbit HAPS High Altitude Platform System HTS High Throughput System LEO Low Earth Orbit LTE Long-Term Evolution MAIT Manufacturing, Integration and Tests MEO Medium Earth Orbit OGS On Ground Station OTN Optical transport Network POP Point Of Presence

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ABSTRACT

Although the first laser communication systems were demonstrated in space in the 1990s, it is only recently that the technology, reliability and economics of space based optical systems have combined with the need for more bandwidth to push them into operation. Developments supported by space agencies pave the way for a commercial use of optical technologies, which are planned to revolutionize communication network architectures by introducing a hybrid terrestrial/space options.

In this context, the goal of the TAO study is to identify a relevant business case based on an all optical satellite system, to detail the corresponding system architecture and to assess the associated roadmap. Two missions have been selected among an initial pool of seven scenarios:

- the white areas backhauling: 10 Gbps of aggregated capacity are sufficient to provide high speed connection to a local access network. This would be a temporary measure, to allow a terrestrial solution to come forward. - the redundancy of terrestrial network for isolated islands, landlocked countries or for any region with a lack of optical fibre redundancy: 100 Gbps class links are required to provide a useful redundancy of the terrestrial network. As in the previous case, the optical link will only operate during the time required to restore the connection.

The two scenarios have technical, operational and commercial similarities. Indeed, they both:

- Operate two bi-directional optical links: since data are carried in the optical digital format, no conversion is required to pass from the terrestrial to the space domains. Compared with a DVB system, this drastically reduces the complexity and the cost of the ground segment. - Manage end to end proprietary links: dedicated optical FEC can be implemented in each OGS, which avoids implanting FEC on-board. In this case the satellite has the same role than an optical repeater, which considerably simplifies the on-board chain - Operate an all optical link with limited capacity (< 100 Gbps), which relaxes implementation constraints and make possible considering a hosted payload option. - Use state of the art photonic components, 10 and 100 Gbps being terrestrial standards. - Operate during a limited amount of time, the corresponding business case being a capacity leasing. This capacity leasing can be proposed by a terrestrial operator as a way to reduce the risk associated to its solution. - Address the same customers, mainly network operators or internet providers - Propose a time limited service, implying that the operational implementation has to be performed within a few days. This requires a transportable ground station.

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Those features have been used to define a system architecture, depicted in the figure hereafter (no on-board processing option)

Architecture of an all optical satellite communication system

Both scenarios consider a lack of the terrestrial network. This means that the need of such a solution will probably gradually decreases with the development of the terrestrial infrastructures. Therefore, the implementation roadmap shall optimize the development time in order to propose a relevant satellite based solution as soon as possible. The critical parts are:

- the 100 W class laser required to deliver 100 Gbps: the linewidth of the booster have to be lower than typically 1 MHz, which means that the ASE has to be mastered. This is not the case today, even in laboratory environment. An alternative solution would be to amplify each of the 25 Gbps channels independently and using a high power multiplexer. - The processing unit (if required) has to generate up to 25 Gbps signals and to perform coding/decoding of the signal. Such equipment is not currently available, the higher HSSL links being around 3 Gbps even if higher performances are expected in the short term.

No critical points have been identified for the transportable OGS. The ground station must have a high degree of automation in order to be operable within a few days with a limited number of operators.

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1. INTRODUCTION

With the increasing usage of high speed internet, video-conferencing, live streaming etc., the bandwidth and capacity requirements are increasing drastically. This trend is expecting to increase in the following years with the emergence of IoT services. This ever growing demand of increase in data and multimedia services has led to congestion in conventionally used radio frequency (RF) spectrum and arises a need to shift from RF carrier to optical carrier. Unlike RF carrier where spectrum usage is restricted, optical carrier does not require any spectrum licensing and therefore, is an attractive prospect for high bandwidth and capacity applications. This is why significant efforts have been made to increase the TRL level of optical communication systems, which will soon become a commercially- viable alternative to the current RF solution.

In this context, the goal of the TAO project is to define a business case and of an all optical communication satellite system and to detail the associated architecture. The logic of the TAO study is illustrated in Figure 1.

Figure 1 : TAO study logic

Latest developments of space based optical communications systems are addressed in the first part of the TAO project. From this starting point, a market analysis have been performed for the space and the ground segments in order to identify the most relevant business case related to the use of an all

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optical communication satellite. This scenario has been analysed from a technical and a business perspective in order to define an implementation roadmap for the selected mission.

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2. STATE OF THE ART

Space based optical communication systems are envisaged for inter-satellite and for space to ground bi-directional links. Each type of orbits may be concerned by the application of optical technologies.

Figure 2 : system configurations considered in the TAO study

Currently, EDRS is the only existing system on the market that uses space based optical technologies. The programme is developed under a public private partnership between the ESA and Airbus Defence & Space. The optical links are used between a LEO and a GEO satellite to reduce the latency due to the visibility of the LEO satellite wrt the ground segment. Since the GEO to ground link is performed by using radio frequency technologies, it is not strictly speaking an all optical satellite system.

LEO Sat constellation is another example of an hybrid optical/RF system: the inter-satellite links are performed by using optical technologies whereas the bi-directional space to ground link is performed in Ka band.

LaserLight is one of the most advanced projects that consider an all optical solution. The MEO based satellite will provide The service capacity of the planned constellation of 12 MEO satellites is in excess of 33 Tbps, comprised of 48 inter-satellite links 200 Gbps optical crosslinks and 72 satellite to ground 100Gbps optical bidirectional links, without reliance on regulated radio frequency spectrum.

Other systems are considering the use of optical technologies, they are summarized in Table 1.

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Mission Optical system Data rate Name Application Use case ISL Feeder Current Planned EDRS GEO relay Relay Optical RF 1.8 Gbps 7.2 Gbps LaserLight MEO constellation Trunking Optical Optical / 100 Gbps LeoSat LEO constellation Trunking Optical RF / 1,2 Gbps BridgeSat LEO constellation internet access Optical TBD / multi-Gbps BATS GEO feeder internet access / Optical / 1 Tbps Terabit GEO feeder internet access / Optical / 1 Tbps O3B MEO constellation User access network Optical RF / TBD OneWeb LEO constellation User access network Optical TBD / TBD Internet.org Multilayer User access network Optical TBD / TBD

Table 1 : synthesis on space based optical systems

Their main characteristics have been summarized in Table 2 for each type of mission.

Feeder GEO LEO / GEO MEO Constellations LEO Constellations

Baseline Goal Baseline Goal Baseline Goal Baseline Goal

Data rate > 40 Gbps 100 Gbps > 40 Gbps 100 Gbps 10 Gbps 100 Gbps 10 Gbps 40 Gbps Range > 2500 km 80000 km 40000 km 80000 km 21000 km 14000 km 1300 km 1000 km

Neighbours 2 2 / / 2 4 4 8 Modulation TBD Analogic TBD Analogic TBD Analogic TBD Analogic ISL BER before FEC 10-3 10-4 10-3 10-4 10-3 10-4 10-3 10-4 Consumption / 200 W 200 W 100 W 100 W 150 W 150 W 50 W 50 W ISL Onboard 2 Tb 10 Tb 2 Tb 10 Tb 1 Tb 5 Tb 500 Gb 2 Tb memory Range 36000 km 36000 km / / 25000 km 30000 km 2000 km 1500 km 100 Data rate 100 Gbps 1 Tbps / / 200 Gbps 1 Tbps 40 Gbps Terrestrial Gbps downlink Modulation Analogic Analogic / / Analogic Analogic TBD Analogic BER before FEC 10-3 10-4 / / 10-3 10-4 10-3 10-4

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Consumption 200 W 400 W / / 500 W 500 W 100 W 100 W

Table 2 : main mission characteristics

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3. MARKET ANALYSIS

The market analysis addressed the space and the ground segments.

3.1 Space based communication systems

The GEO telecommunications market is a highly competitive business for satellite manufacturers and there is a growing challenge to provide new innovations. The main issues concern the reduction of the cost/Gbps and the flexibility increase of the whole system. Finally they also ask for a shorter schedule in term of manufacturing.

In the longer term, the market will be driven by: . The inclusion of satellite in 5G infrastructures, offering to everyone the opportunity to benefit from reliable services, whether at home, on the move or in the air, . The opportunity offered by space solutions to guarantee resilience and worldwide coverage, . A new ecosystem pushed by new investors and Internet players (e.g. GAFA), opening opportunities for new forms of infrastructures, mixing GEO highly capable satellites, non GEO constellation and hybridization of future 5G terrestrial networks, . Technological and industrial breakthroughs opening new avenues for use of space for commercial data exploitation and social benefits.

Figure 3 : Satellite technology evolution

LEO communications satellites are advantageous for operators as they enable the use of terminals with less power and smaller antennas, and also make it possible to obtain low latency. However, these benefits are offset by the need to deploy many more satellites for complete continuous Earth

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coverage, and most often by the need to track the satellite passing above. There was a first wave of interest in LEO constellations in the mid to late 90s, with notable investors and/or sponsors such as Motorola with the Iridium 1st generation, Celestri, Globalstar 1st generation, etc. Most of these initiatives did not get off the ground, due to budget overruns and difficulties tying up the business plans. In the end, only Iridium, Globalstar and Orbcomm were deployed and are still in operation (with a second generation for Iridium and Globalstar) and are used for low-rate services and applications. In every case, the initial investors suffered huge losses.

Satellite constellations again found favour since 2007, in MEO, with the O3B satellite initiative and then with the forthcoming LEO constellations (OneWeb, LEOSat, TeleSat, etc.) A Non-exhaustive list of non-GEO constellation initiatives is summarized in Table 3.

Class of satellite Non-exhaustive list of non-GEO constellation initiatives

0-10kg 4skies, Aprize, Astrocast, Fleet.Space, Outernet, Prometheus, Kepler

10-100kg BitSat, Blink Astro, Exact Earth, Sky & Space Global, Spire

100-500kg Astrome, BridgeSat, KasKilo, OneWeb, SpaceX, Strela, Xinwei

500-1500kg Iridium Prime, LaserLight, LeoSat, O3BNG, SpaceBelt, Theia, Yaliny

Undetermined 3ECOM-1, ASK-1, Boeing, Telesat, MCSat, Sirion Global, SSMI, Viasat

Table 3 : Non-GEO Communications Constellations Projets, 2017-2021

3.2 Terrestrial communication systems

Capable of cost-per-bit figures lower than any other alternative and throughput-times-distance products in the order of 1018 bit/s∙km, fibre-optic communications are end-to-end essential in today’s data communication. From few-meter transmission and up to thousands of kilometres, optics is currently employed everywhere; subtly evincing how profoundly linked its technical evolution is to the global trends in data traffic and services. Concretizing, the key requisites and facts driving the future of network design and development and summarized into three distinct groups of abstract network trends (pressure points); that is: more data, more dynamism and more complexity.

More data

As technology develops and penetrates into our life in a plethora of different formats; capturing, processing and transferring information becomes progressively inexpensive. In other words, the cost

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of data is diminishing. This observation combines with the growing population with internet access (from 80% in 2015 to 90% expected in 2020) plus the increasing amount of connected devices to cause the gigantic increase in data traffic volume forecasted in the upcoming years. In numbers, it translates to traffic growths through 2017 of 440% in cloud and datacentre, 560% in metropolitan area networks and around 320% in core; overwhelming factors calling for network adaptation.

Figure 4 : Evolution of connected home devices

The consequence is that 100-Gbps (100G) line rates are not only an option but a necessity in great fraction of the network; a patent fact in the market evolution.

Another aspect concerning 100G expansion is that this technology is now reaching a broader set of service providers and application areas. This brings up a remark which is very much related to the diversity of traffic profiles at different layers: while it is true that as of 2017 all service providers and application areas seem to converge to 100G as the most desirable line rate to sustain the throughput growth, all of them present different techno-economic constraints. Furthermore, the need for faster interfaces ramps up differently depending on the segment, suggesting that >100G solutions’ design, as well as the general research effort and technology development, will progressively shift to better satisfy the needs of the leading market.

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More dynamism

Basically, as we push components and transport equipment to their reliable limits of operation, dynamic resource allocation as a means of increasing the bit-transport efficiency becomes absolutely crucial. As a logic extrapolation of the latter, we are experiencing the raise of a disruptive network design paradigm in some network segments in which optimum system operation is compromised in favour of on-demand resource allocation for guaranteeing the just-right quality of service in a way that remains transparent to the end user. Class-of-service differentiation, flexgrid WDM, elastic-optical networks, flexible transponders and meshponders, hardware/network virtualization, FlexEthernet, OTUCn, and a plethora of other relatively new concepts and technological ensembles manifest the above-mentioned trend. Moreover, in addition to the seemingly infinite capacity and fast resource adaptability, emerging services such as IoT, augmented reality, or connected vehicles, set specially demanding targets in terms of reliability and foremost latency.

More complexity

Exactly in the same way that self-driven cars are much more complex to design than conventional cars in order to simplify our lives, the future data network must get ironically complex in order to enable the simplicity and convenience promised by automation, software-based programmability, on- demand resource allocation, or the broad set of new services envisioned after 5G. And this complexity touches upon a wide range of factors, from technological to regulatory or economical nature; for instance: the assurance of compatibility across transport standards or multi-vendor equipment, the assurance of data security in the midst of the information-sharing era, the conception of new business models fed on this technological revolution, or the adaptation of the network- exploitation regulations for operators and service providers.

While all the above transitional matters are important and necessary, some require more immediate attention as they sustain the conceptual feasibility of the one unified future network fabric. One clear pillar is data protection and cyber security, because we cannot simply delete layers, foster transport transparency, and implement data-processing disaggregation without enabling equally seamless privacy and protection systems. This is, however, extraordinarily complex. Not only our data is to be stored and processed on multiple distributed datacentres, thus increasing the number of phishing- susceptible edges nodes our data goes through, but also the volume of data per capita that we consume continues to grow at an unprecedented rate.

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4. IDENTIFICATION OF SCENARIOS

4.1 Considered scenarios

Several scenarios have been identified regarding the all-optical constraint. All of them are part of the 5G problematic and closely intricate with terrestrial considerations. These scenarios all benefit from the generic satellite characteristics and the full-optical capability provides both high speed and high throughput capabilities, participates to cost reduction and does not require RF spectrum allocation. They are listed hereafter.

1 – Traffic off-loading from fibre-based networks with strong structural degradation or power-budget limitations. Full-optical satellite can support 5G growth and of particular bandwidth demands for social events.

2 – Isolated areas and islands with down to 1 fibre link or no fibre connection (white area) to access the core network. Full-optical satellite can provide backhauling solutions or temporary connectivity in case of link breaks or failures.

3 – Provide connectivity in disaster-recovery (man-made or natural) and war areas. Full-optical satellite is a temporary solution to restore networks with limited ground infrastructures or limited access to specific areas (backhauling).

4 – Redundancy is often required by the client to increase the robustness of data transport. The fibre- based redundancy is unused almost 100% of the time, thus raising the cost/bit to unacceptably high values. Full optical satellite can provide redundancy for an acceptable cost.

5 – By-pass certain geographical areas for security or sovereignty reasons (landlocked countries). Full-optical satellite is the only solution to offer a backhauling solution to connect specific areas to the core network avoiding specific geographical areas.

4.2 Selection of scenario

Several business and technical criteria have to be considered to identify the most relevant scenario. Nevertheless, common-sense considerations allow making a first selection:

- The capacity of the terrestrial network is several times larger than optical satellites. In addition, this capacity can easily be increased by switching on an additional fibre. Therefore, the offload risk of the terrestrial network is very limited in normal conditions and using optical satellite in that case is not relevant. - In disaster areas, in war time or after a natural disaster, emergency communication kits allow an autonomous connection within 5 minutes. In such conditions, the emergency need mainly

concerns low data rate capabilities (internet, chat, email, file sharing). Setting up a telescope in (at least) few hours in order to have high data rate in good weather conditions is not a relevant solution compared to the commercial communication kit, which is set up in a few minutes and can operate in any weather conditions.

Scenario 1 & 3 are therefore discarded. In addition, scenario 2 considers two situations:

- link failure in case of white areas connected with one single fibre link: this case is similar to the scenario 4 relative to the redundancy of the communication link. - Provide connectivity in case of lack of terrestrial network, which is the same application case than scenario 5.

Scenarios 2, 4 & 5 can therefore be classed in two groups:

- Scenario A: provide connectivity in case of lack of terrestrial network - Scenario B: provide redundancy in case of failure of terrestrial network

4.3 Scenario A: provide connectivity in case of lack of terrestrial network

Features:  Typically 10 Gbps optical links for rural areas, up to 50 Gbps for more densely populated areas  Shared service with spatial flexibility  Transportable OGS (service within days/weeks)  Potential customers : white areas

Figure 5: Illustration of Scenario 2 - All optical backhauling of white areas

4.4 Scenario B: provide redundancy in case of failure of terrestrial network

The main features of this scenario are:  100 Gbps optical links  Shared service with spatial flexibility  Transportable OGS (service within days)  Connection through POP  Potential customers : isolated islands, landlocked countries

Figure 6: Illustration of Scenario 1 - Redundancy of terrestrial network

For both scenarios, the potential customers of an all optical solution are cable operators, cable internet providers and mobile network operators. They may be interested by a short term installation with a high capacity service, mainly located into countries with precarious internet connections. This includes:

- isolated islands, - countries with low internet diversity at the international frontier (less than 2 companies) - landlocked countries, which aim to guarantee their national sovereignty and to avoid high connection costs.

5. ARCHITECTURE & ROADMAP OF AN ALL OPTICAL SATELLITE SYSTEM

The architecture of an all optical satellite system is detailed there for the dimensioning case, ie the scenario B that considers 100 Gbps bi-directional links. However, prior to that, a trade-off has to be addressed about the on-board architecture

5.1 On-board architecture

As for long haul terrestrial technologies, repeaters or amplifiers can be envisaged for the space segment. As its name suggests, the amplifier magnifies the distorted signal whereas the repeater receives the optical signal, converts it in electrical form, and performs reshaping & amplification operations on the signal before re-transmission.

Figure 7: Difference between an optical amplifier and an optical repeater

The repeater option implies carrying a processing unit on board, with the corresponding technical challenges related to the spatialization of a 10 or 25 Gbps class ASIC or FPGA, currently limited around 3 Gbps.

The amplifier option may be considered if an efficient FEC can be implemented in the two OGS. This FEC has to correct atmospheric effects due to the up- and downlink and the noise related to the optical amplification chain on board. Such a code is currently difficult to assess since up- and down- links has not been experimentally measured yet. Nevertheless, we can state that a FEC should allow correcting the whole optical channel at the cost of its efficiency and latency, which has to be evaluated and/or optimized in a further study.

The corresponding architectures are illustrated in figures hereafter

Figure 8: architecture of an all optical satellite system with on-board processing (repeater option) and associated TRL level for a 100 Gbps optical link

Figure 9: architecture of an all optical satellite system without on-board processing (amplifier option)

If on board processing is required, the system architecture shall be aligned with the availability of the processing unit in order to reduce the development time. Optical and/or digital multiplexing techniques may be considered for the 100 Gbps scenario, even if there is a SWaP penalty. Naturally, the development of a 100 Gbps ASIC will strongly reduce the power consumption of the processing function.

5.2 On-ground architecture

The on-ground architecture is the symmetrical of the space segment, illustrated on Figure 10 with the associated TRL levels.

Figure 10: Functional architecture of a ground station and corresponding TRL levels

One of the main features of the TAO OGS is the ability to be shortly deployable and to have an autonomous operation. An example is the TOGS developed by DLR/Mynaric, but an effort have to be made to operate the station automatically and/or remotely.

For the scenario 2 (all optical backhauling) the presence of facilities would be preferable in order to avoid the development of an “extreme robotic OGS”, even if it can be considered from a technical

point of view (parachute drops, automatic deployment, alignment, calibration, pointing and tracking thanks to dedicated solar panels, etc).

5.3 Roadmap for an all optical satellite system

Since the need of an all optical satellite will decreases with the development of the terrestrial infrastructures, the implementation roadmap shall optimize the development time in order to propose a relevant satellite based solution as soon as possible.

The development steps are:

 Defining the detailed architecture of the terminal and the optical chain, the finalized architecture being dependant of the DPU trade-off.  The qualification of the optical components can start immediately after the decision of making an all optical satellite system (T0), one year and a half being required to qualify the Rx & T& chains, whether for a 10 or a 25 Gbps optical chain (up to 25 Gbps, the bandwidth has minor impacts on the availability of photonic components).  The development of the optical booster can also start at T0, the booster being probably on the critical path. Two years can be allocated to the development and qualification, since the booster has to be qualified at the last stage of the optical chain MAIT (Manufacturing, Integration and Tests)  The DPU being another critical component, the development of the relevant processor may start at T0. Currently available FPGA based processing can be envisaged (vs. ASIC) by digitally multiplexing 10 or 25 Gbps channels. ASIC technology lowers the power consumption of the processing unit by about 30 %, but it requires a specific development that can be considered for mid-term applications (> 2023 if the T0 is in 2019).  The MAIT of the aerial part (telescope, tracking, fibre injection) can start 18 Months after T0 and requires one year to finalize the qualification of all the components.  18 Months are also required to perform the AIT of the terminal and the satellite.

The optical booster is on the critical path of the ground segment, the corresponding developments shall begin at least at T0. The adaptive optics subsystem also requires subsequent developments: increasing the bandwidth of the correction loop and increasing the operational robustness of the subsystem (auto-alignment, automatic calibration, etc.) The corresponding developments shall start 6 Months after T0, one the system requirements are fixed.

The MAIT schedule of the optical elements are aligned with the MAIT of the optical terminal, and the integration of the station on a transportable platform (van, container, etc.) is aligned with the AIT phase of the terminal and the satellite.

The launch of the optical satellite and the validation phase can therefore be planned 4 years after T0.

6. CONCLUSION

The TAO project identified two potential business case of an all optical satellite solution: a 100 Gbps link to ensure the redundancy of the terrestrial network and a 10 Gbps link to perform an all optical backhauling. Both solutions are point to point links and directly use the terrestrial modulation formats. An end to end FEC is therefore considered, allowing locating the processing function on the ground (the feasibility of this point should be validated by a comprehensive study).

Both scenarios consider a lack of the terrestrial network. The need of such a solution will probably gradually decreases with the development of the terrestrial infrastructures. Therefore, the implementation roadmap shall optimize the development time in order to propose a relevant satellite based solution as soon as possible.

The frequency bandwidth of the optical booster (MHz class) is a critical element of the optical system and corresponding development shall begin rapidly. High power multiplexing shall be considered to overpass the availability of high power boosters, with also a slight SWaP penalty due to the multiplication of the optical channels. Typically, four 20 W boosters will be required for a 100 Gbps optical terminal. Such components may be available after 18 Months of development time.

No other critical points have been identified, and the development of a 100 Gbps all optical satellite system can be envisaged within 4 years.