66th International Astronautical Congress, Jerusalem, Israel. Copyright ©2015 by Yaliny. All rights reserved. IAC-12-B2.1.4 MOBILE SATELLITE COMMUNICATION SYSTEM BASED ON NEW DIGITAL PHASED ARRAY BEAMFORMING TECHNOLOGY Mr. Alexander Kharlan Yaliny, Russian Federation, [email protected] Mr. Vasily Ruchenkov Yaliny, Russian Federation, [email protected] Mr. Vadim Teplyakov Yaliny, Russian Federation, [email protected] Yaliny is a young and innovative company whose aim is to create a satellite communication system with a whole new level of performance. It is planned that the system will, having been fully deployed, provide communication services and fast Internet connection to any customer all over the globe. First and main segment will be a satellite constellation, consisting of 135 satellites in low earth orbits, each equipped with a hybrid phased array antennae combining digital and analogue beamforming. The highlight of the phased array itself is the beamformer fully developed by Yaliny engineers. It is essentially a PCB – a dielectric base with metallic layers, providing transmission and receiving linearly polarized signal types. The main advantage here is that for deviating the antennae's directional pattern only half as much controlling elements are needed comparing to traditional phased array structure. This is achieved due to multimode structure of the beamformer. Its construction also provides an opportunity to combine two PCBs into a special crossed construction, thus with different profiles of independent powering of the PCBs any kind of polarization can be attained. The second segment of the communication system will be its ground infrastructure. The satellites communicating with each other using a specially developed intersatellite optical communication hardware will also use a separate dish antenna for broadband connection with ground stations, via which they will be able to connect to the Internet. It is planned to strategically locate ground stations in different regions of the world to provide fast and convenient communication services. The third segment is the customer terminal – a device size of a regular smartphone capable of communicating with customers' smartphones or computers using Wi-Fi or Bluetooth, and the satellites. The link is designed so that its margin will allow to have up to several million users all over the world utilizing the network simultaneously. Today the company already possesses all the technologies needed for the cause as well as the communication system prototype already manufactured. I. INTRODUCTION In the 21st century mobile satellite communication can represent a paradigm shift to how a global communication network can be established. Satellites rapidly become significantly cheaper every day, with new technologies appearing every now and then which can drastically boost their performance, be it a communication satellite or not. At the same time, mobile communications develop not so fast nowadays, one of the major issues with them being the roaming – a cost prohibitive feature leading to a fact that the vast majority of people have next to no communication at all while abroad, except for the WiFi. Yaliny is an innovative company whose aim is to create a satellite communication system with a whole new level of performance. It is planned that the system will, having been fully deployed by the year 2018, provide communication services and fast Internet connection to any customer all over the globe. IAC-15-B2.1.4 Being the one artificial object to fly over the state borders without any formalities involved, a satellite is a primary means of connecting people in the future. Satellite communications are by no means a new solution: a number of such networks is already present. But having been deployed a long time ago some of them have become obsolete, due to their initial price charging ridiculous fees for below average quality or just poor services. To replace them the use of all the cutting edge technologies available is needed for the solution to be cost-effective and flexible. That is why Yaliny’s primary goal is to merge the newest satellite technologies into an efficient solution to provide communication services all over the globe. Today when new satellite communication systems are planned, requirements lodged on their antennae systems become more and more stringent and contradictory: high efficiency and power are often demanded as well as multibeam directional pattern forming and adaptive control, organized in severe space conditions. Thus for the purpose of providing mobile Page 1 of 4 66th International Astronautical Congress, Jerusalem, Israel. Copyright ©2015 by Yaliny. All rights reserved. satellite communication services only phased array antennae system can efficiently solve all the problems posed. This paper presents an overview of the Yaliny’s future LEO satellite communication system, its concept, major features of the satellite being designed, and gives a description of its payload and engineering solutions involved in its design. II. CONSTELLATION CONCEPT This section provides a description of the constellation concept, as well as describes how the global coverage demands are being met. It also gives an overview of launch possibilities and of how they affect the whole mission plan. II.I Operating constellation To effectively operate the communication system has to provide communication services all over the world. The coverage must be global – any subscriber must have a complete access to all the services of the system regardless of his location on the globe. Thus, having in mind that GEO satellites as well as the others operating on congruent altitudes cannot provide the required performance of the communication system due to the excessive path loss, a network of at least several dozen LEO satellites is needed to provide a global coverage. Yaliny constellation will consist of 135 operating satellites and also a number of additional satellites for redundancy purposes, some of them in orbit and other ones on Earth. Orbital planes The satellites will be deployed in nine different orbital planes, each orbit Sun-synchronous (SSO), with RAAN difference 22.5 Fig. I: Orbital planes positioning. IAC-15-B2.1.4 Orbital planes and how they are positioned can be seen on fig. I. Though the satellites are not built for Earth observation, and the choice of the SSO as an operational orbit may seem questionable, it is in fact justified. As the satellites are very energy-effective with up to 10 kW of power being consumed by the payload and the subsystems combined, it is highly advisable to have a comparatively simple way of gimballing the solar panels in order to harvest a maximum possible amount of energy. One of the ways to reduce the overall complexity of the solar array mechanical hardware is to place a satellite into an orbit where the solar beta-angle remains the same or approximately the same during the mission lifetime. SSO is such an orbit. It allows us to assign a certain beta-angle to each orbit, and this same angle will determine the position of one of the axis of the solar panel. This also simplifies the thermal protection system – the solar radiation flow vector always rotates the same way, which does not vary, as the beta-angle does not change, depending almost only on the orbit local time of ascending node (LTAN). In-orbit positioning Each of the nine orbital planes has 15 operating satellites in it. The difference in the arguments of latitude of any two neighbour satellites in one orbital plane will be u 24 [2] Besides, positions of two corresponding satellites in two neighbour planes so differ that, if looking from the satellite along its velocity vector, the satellite to the right is 16 degrees ahead, and the satellite to the left is 8 degrees ahead (Table I): Plane#1 [1] Plane#2 Plane#3 Plane#4 u = 32° Sat#3.2 u = 24° Sat#1.2 Sat#4.2 u = 16° Sat#2.1 u = 8° Sat#3.1 u = 0° Sat#1.1 Sat#4.1 u = 352° Sat#2.15 u = 344° Sat#3.15 Table I: Initial satellite positioning net. Such positioning allows any satellite to be in the centre of a regular hexagon, each apex of the hexagon being another satellite. All satellites are connected with each other with an intersatellite optical link. Each satellite can connect with the satellite flying ahead of it and the one flying behind in the same orbit, and with two satellites in each of the neighbour planes. For example, satellite #3.1 (see Table Page 2 of 4 66th International Astronautical Congress, Jerusalem, Israel. Copyright ©2015 by Yaliny. All rights reserved. I) connects to satellites 3.2, 3.15 (in the same orbital plane), 2.1, 2.15, 4.1, and 4.2 (in neighbour planes). Thus, the described positioning of the satellites makes it possible to maintain full coverage at any moment of the time. Coverage zones intersect each other, with interpenetration between coverage zones being less significant in equatorial areas and more significant in polar areas. Having in mind the fact that the majority of the consumers dwell at latitudes of 25..30 or more degrees, the intersection zones may be used in order to distribute the subscribers in them between two satellites, thus significantly decreasing their peak loads. II.II Redundancy It couldn’t be very well expected that such a vast amount of satellites will work for years without any failures. In a system with more than a hundred operating spacecraft there must be a number of additional satellites strategically allocated between the orbits for redundancy. The approach to the problem may vary, but the key principle of it remains the same: every single element at any level of the system must be designed so that the system meets the reliability demands without enormous amounts of expensive redundant elements. II.III Launch and deployment Bla with an equation. m m F12 G 1 22 û12 r2 r1 II.V Graph Lines, Drawings and Tables Use black ink on white manuscript and position to fit within one of the columns on the page, and ensure that they remain still readable. Tables with a moderate amount of information should be positioned within one column. Tables, graphs or pictures with large amounts of information may extend across two columns. Venus Earth Mars Jupiter M/ME 0.82 1 0.11 317.89 e 0.007 0.017 0.093 0.048 R (AU) 0.7233 1 1.524 5.203 i (deg) 3.40 0 1.85 1.30 T (years) 0.62 1 1.88 11.86 Table X: Title of table, left justified, subsequent text indented. Heading centred. Do not use vertical lines within the table; use horizontal lines only to separate headings from table entries II.VI Captions, Graph Axes, Legends Captions, graph axes, legends, etc. should be large enough to remain readable. II.VII Footnotes, Symbols and Abbreviations Footnotes should be cited using symbols in this order: *, t, :t, §, <J[, **, tt, :t:t. Use only standard symbols and abbreviations in text and illustrations. II.VIII Page Numbers Indicate page numbering at the bottom of each page. [1] II.VI Illustrations and Captions It is important to remember that all artwork, captions, figures, graphs and tables will be reproduced exactly as you submitted them. (Company logos and identification numbers are not permitted on your illustrations). III. MISSION ANALYSIS This section provides an overview of the mission plan of every satellite operating within the Yaliny constellation. It describes the satellite’s deployment, the process of its delivering itself to the operating point, as well as how the stationkeeping maneuvers are performed to provide the required mission lifetime. III.I. First hours of flight Bla bla III.II. Maneuvering Bla bla III.III. Stationkeeping Bla bla Fig. X: Title of the figure, left justified, subsequent text indented. Place figures at the top or bottom of a column wherever possible, as close as possible to the first references to them in the manuscript. Restrict them to single-column width unless this would make them illegible. IV. SATELLITE CONCEPT The ways of meeting the mission requirements and engineering solutions implemented in the satellite are discussed in this section. It gives a detailed overview of the satellite’s subsystems, describes the power supply scheme and system reliability. IV.I. Subsystems IAC-15-B2.1.4 Page 3 of 4 66th International Astronautical Congress, Jerusalem, Israel. Copyright ©2015 by Yaliny. All rights reserved. Bla bla V.II. Вася 2 Bla bla Bla with a reference1. IV.II. Power efficiency Bla bla IV.III. Reliability Bla bla V.III. Вася 3 Bla bla V. ВАСЯ VI. CONCLUSIONS V.I. Вася 1 Bla bla 1 Blaa IAF Secretariat, 2012, Instructions to the Authors for the 63 rd International Astronautical Congress – Naples IAC-15-B2.1.4 Page 4 of 4
