Satellites in orbit have already become an integral part of our lives. They help us find our way in an unfamiliar city, track a parcel on the other side of the world, and even access the Internet without terrestrial networks. There are various global navigation satellite systems (GNSS) – the American GPS, the European Galileo, the Chinese BeiDou, and regional ones, such as Japan’s QZSS and India’s NavIC. In addition to navigation, large satellite communications systems, such as Starlink (USA) and OneWeb (UK), are also being deployed, providing broadband Internet from space. In this article, we will look at how the main satellite navigation and communication systems work and how they differ, from the number of satellites and types of orbits to coverage and purpose.
Navigation systems work on a similar principle: each navigation satellite continuously transmits a radio signal with very precise time and coordinates. The receiver (for example, in your smartphone or car) receives signals from several satellites at the same time and calculates the distances to them based on the difference in their arrival times. Based on this data, the receiver determines its location on Earth. To get an accurate three-dimensional position, signals from at least four satellites are needed. Communication systems work differently: they create an orbital infrastructure to transmit data (Internet traffic, telephone messages, etc.) between remote points on Earth. For this purpose, dozens or even thousands of telecommunication satellites form a constellation that provides signal coverage of large areas of the Earth. Below, we will take a closer look at each of the leading systems.
GPS (USA)
GPS (Global Positioning System) is the oldest and most widely used global navigation system deployed by the United States. Created for military use, today, GPS is available to civilian users around the world free of charge. The GPS satellite constellation consists of about 31 active satellites placed in medium Earth orbit (approximately 20,200 km above the Earth). The orbits are distributed in such a way that at any given moment, the user can see at least 4-6 satellites in different parts of the sky. Each satellite is equipped with high-precision atomic clocks and transmits time signals and navigation messages. GPS receivers determine the coordinates by measuring the signal transit time from several satellites and calculating the distances to them.
GPS provides global coverage with a typical horizontal accuracy of several meters for civilian users. For example, an ordinary smartphone determines the location with an error of about 5 meters under favorable conditions (open horizon, good signal reception). For professional purposes, the accuracy can be increased to centimeters using special dual-frequency receivers and differential correction systems. The GPS orbital constellation is constantly being modernized: new satellites with improved signals and higher accuracy are launched to maintain the reliability of the system. GPS is used everywhere – from car navigation and aviation to smartphones, geodesy, and banking time synchronization.
Galileo (EU)
Galileo is a global navigation system developed by the European Union in cooperation with the European Space Agency (ESA). Unlike GPS, Galileo is under civilian control, and Europe created it to be independent of the US and other systems. Currently, the Galileo constellation, after the launch of GSAT-29 and -30 (April 2024), consists of 30 satellites in medium Earth orbit at an altitude of about 23,222 km. The satellites are deployed in three orbital planes with an inclination of ~56° to the equator, providing global coverage from the equator to the polar latitudes. The first Galileo signals began to be used in 2016.
Galileo is known for its high positioning accuracy. Thanks to the transmission of signals on two frequencies for civilian users (which helps to compensate for the influence of the ionosphere), the system provides location determination with an error of about 1 m in standard mode. In terms of open signal accuracy, Galileo surpasses GPS (where the error is ~3 m). In addition, in 2023, a special High Accuracy Service was launched, providing even more precise corrections, up to 20 cm in the horizontal plane for professional applications. Galileo is also integrating a search and rescue (SAR) service: The satellites relay distress signals from beacons and inform the victim that the signal has been received. Today, most modern smartphones and navigators support Galileo along with GPS, increasing the overall reliability and accuracy of positioning.
BeiDou (China)
BeiDou is a Chinese global navigation satellite system. The name comes from the Chinese word “Northern Ladle”, which means the constellation of the Big Dipper. The system was developed in stages: the early version of BeiDou-1 was regional, BeiDou-2 (Compass) provided coverage of the Asia-Pacific region, and in 2020, BeiDou-3, a full-fledged global system, was deployed. Currently, its orbital constellation consists of 35 satellites. Unlike other GNSS, BeiDou has a mixed orbital configuration: some satellites move in medium Earth orbit (~21,500 km), and some are located in geostationary (about 35,786 km) and inclined geosynchronous orbits. In particular, the final configuration includes 3 satellites in geostationary orbit, 3 in inclined geosynchronous orbits, and 24 in medium orbit. Geostationary satellites “hover” over specific points above the equator and are particularly useful for providing regional services in the China area (e.g., short text messages and differential corrections).
Source: ESA
In terms of accuracy, the Chinese system is close to its competitors. According to official data, the standard error in determining coordinates is ~10 meters for the open BDS service. In real-world conditions in China, the accuracy through the use of local ground stations can reach several meters, and closed signals with higher accuracy are available for military and special users. The BeiDou system is fully managed by the Chinese government. Today, more and more chips in smartphones and navigation devices support BeiDou along with GPS and Galileo, which increases the reliability of location determination (multi-system receivers can use more satellites in the sky). The launch of the last, 35th BeiDou-3 satellite in June 2020 was a landmark event – China officially announced the full deployment of its global navigation system.
QZSS (Japan)
QZSS (Quasi-Zenith Satellite System), or “Michibiki”, is a regional navigation system in Japan. Unlike the global GNSS, QZSS is designed primarily to supplement and improve the accuracy of GPS in East Asia and Oceania, especially in cities between skyscrapers and in the mountains, where the GPS signal can be obscured by obstacles. The system is owned by the Japanese government and operated by QZSSS. QZSSS officially began providing services in 2018, when it had 4 satellites in orbit. Japanese engineers chose the so-called “quasi-zenith” orbits for them, which are highly elliptical geosynchronous orbits that allow the satellite to stay high above a certain point (near Japan) for most of the day. The QZSS orbit is synchronized with the Earth’s rotation (period of ~24 hours) and inclined at an angle of ~43°, which allows the satellites to hover almost at the zenith over the territory of Japan for a long time. QZS-6 is already providing a new generation of precision services and defense monitoring, and QZS-5 is preparing to complete the deployment of a full-fledged, fault-tolerant Japanese navigation grid by the end of 2025.
QZSS plays the role of a supplementary system: it broadcasts additional GPS-compatible signals, as well as differential corrections that improve positioning accuracy in the region. In particular, QZSS provides the Sub-meter Level Augmentation Service (SLAS), a sub-meter correction service, and even the Centimeter Level Augmentation Service (CLAS), a centimeter-level accuracy service for special receivers. Tests show that CLAS can achieve an accuracy of about 10 cm in real time in Japan. Thus, QZSS significantly improves the quality of navigation on the Japanese islands: even in densely built-up areas, the signal from quasi-zenithal orbits comes at a more direct angle than from GPS satellites located above the horizon. In the future, Japan will have its own independent regional navigation system compatible with other GNSS.
NavIC (India)
NavIC (Navigation with Indian Constellation) is an Indian regional navigation system. Formerly known as IRNSS (Indian Regional Navigation Satellite System), the name NavIC (which is consonant with the word “navik”, i.e., ‘sailor’ or “helmsman”) was adopted in 2016. The system belongs to the Indian Space Research Organization (ISRO) and is designed to provide independent navigation services in India and within ~1500 km around it. The NavIC orbital constellation consists of 7 satellites: three of them are placed in geostationary orbits (above the equator and constantly “hover” over fixed points at longitudes 32.5°E, 83°E and 131.5°E), and four more are in inclined geosynchronous orbits (inclination ~29°, longitude of the ascending node 55°E and 111.75°E). All the satellites are located at an altitude of approximately 36,000 km, making one rotation per day.
NavIC provides regional coverage of India with positioning accuracy for civilian users up to 20 meters. This is slightly inferior to global systems, but sufficient for a wide range of navigation tasks. The system provides two main modes: Standard Positioning Service for everyone and Restricted Service for the military and intelligence agencies. In recent years, India has been actively promoting NavIC support in smartphones and car navigators to increase its popularity. For example, some new phone models are already compatible with NavIC signals. The motive for creating its system was the desire for strategic autonomy, so that in the event of a conflict or disruption, Indian military and civilian services would not be dependent on GPS or GLONASS. In 2023, ISRO began to upgrade the NavIC constellation: a new generation of satellites was launched with support for an additional L1 frequency for better compatibility with receivers and improved accuracy. Despite its regional scope, NavIC is integrated into the international search and rescue system Cospas-Sarsat and is recognized by the International Maritime Organization as part of the global radio navigation system.
Starlink (USA)
Starlink is a global satellite communications system created by the private American company SpaceX. Its goal is to provide broadband Internet access anywhere on the planet using an orbital constellation of thousands of small satellites. Unlike navigation systems, Starlink uses a low Earth orbit (LEO) with an altitude of about 550 km. Satellites at this altitude rotate rapidly (full rotation ~95 minutes) and cover a relatively small area of the Earth’s surface, so a large number of them are needed for global coverage. SpaceX is gradually deploying one of the largest constellations in history: as of May 30, 2025, there are 7,578 satellites in orbit, of which 7,556 are operational, forming a grid of dozens of orbital planes. The final first-generation configuration includes ~12,000 satellites, and the company has authorization to deploy up to 42,000 in the future.
Source: SpaceX
Each Starlink satellite weighs ~260 kg and is equipped with flat phased array antennas for communication with user terminals, as well as laser links for data exchange between satellites. Starlink users have a special small satellite dish (“dish”) that automatically monitors the movement of the vehicles in the sky. The signal from the terminal goes to the nearest satellite, is transmitted between satellites (or to the nearest earth station), and then goes to the Internet. Since the satellites fly low, the signal delay is short – ~20-40 ms, similar to the terrestrial Internet. However, each satellite stays above the horizon of a particular terminal for only a few minutes, so the network is designed so that one antenna has time to automatically switch from one satellite to another without losing connection.
Starlink already provides high-speed Internet to millions of users in dozens of countries. The system is especially useful in regions where there is no developed terrestrial infrastructure, such as rural areas, mountainous regions, and ocean shipping routes. Starlink is also used to provide communication during emergencies and in areas of military conflict where traditional networks are destroyed or inaccessible. SpaceX continues to launch new batches of satellites regularly (dozens of Falcon 9 rockets are launched every month), replacing retired satellites and expanding coverage. In addition, second-generation satellites (V2 Mini) with higher bandwidth are being deployed. In the coming years, Starlink plans to launch a Direct-to-Cell service, which will allow ordinary smartphones to connect directly to its satellites to send SMS and make calls, as well as provide global Internet for aviation, ships, and even polar regions.
OneWeb (Great Britain)
OneWeb is another mega-grouping of satellites for Internet communications. Unlike Starlink, the OneWeb project is focused more on corporate and government customers, providing Internet coverage for telecom operators, maritime and air carriers, and remote communities. OneWeb’s satellites are also placed in low Earth orbit, but much higher than Starlink’s – about 1,200 km above the Earth. They move in polar orbits (drawing meridians), so a relatively smaller number of satellites is sufficient for global coverage. The first phase of the system will consist of 648 satellites in 12 orbits with an inclination of ~86.4°. This will be enough to provide Internet coverage of almost 100% of the world’s populated areas (at least 600 active satellites are required for global service). As of mid-2023, OneWeb has already launched most of the planned satellites – more than 630 satellites in orbit – and announced the completion of its first generation of constellation.
Each OneWeb satellite weighs ~150 kg and is equipped with Ku-band transponders for Internet communications. The system uses the principle of a “reverse gateway”: user terminals (on the ground, in airplanes or ships) communicate with the satellite, and the latter transmits traffic to the nearest ground station connected to the Internet. Due to the higher orbit, the signal delay is somewhat longer (~50-100 ms), but one satellite covers a larger area, so fewer satellites are needed for global coverage. OneWeb plans to provide Internet speeds of up to ~50-100 Mbps per user. The company is focusing on cooperation with telecom operators: the business model implies that local partners will distribute the Internet from OneWeb to end users (unlike Starlink, which works directly with customers through its terminals).
OneWeb survived a bankruptcy relaunch in 2020, when a consortium of investors led by the UK government and Indian company Bharti Global rescued the project. Subsequently, the European satellite operator Eutelsat joined the co-owners, and in 2022-2023, OneWeb completed the deployment of the first stage of its satellites using partner rockets. Currently, Eutelsat OneWeb is planning the next generation of satellites that will further increase the network capacity. Competition in the satellite Internet market is growing – in addition to Starlink and OneWeb, Amazon (Project Kuiper system) and Chinese companies are developing similar projects. However, OneWeb has already carved out a niche by signing agreements to provide Internet access to Arctic regions, airliners, cruise ships, etc., where traditional communications are not available.
Comparison of systems
Here are the main parameters of the satellite systems under consideration: the number of active satellites, orbit type, geographic coverage, typical positioning accuracy (for navigation systems), and the main purpose of the system:
| System (country) | Number of satellites* | Orbit type (average height) | Coverage | Accuracy (civilian) | Purpose |
| GPS (USA) | 31 | MEO (~20, 200 km) | Global | ≈ 5 m | Navigation |
| Galileo (EU) | 24–28 | MEO (~23,200 km) | Global | ≈ 1 m | Navigation |
| BeiDou (China) | 35 | MEO + GEO / IGSO | Global | ≈ 10 m | Navigation |
| QZSS (Japan) | 4 (7 planned) | Elliptic GEO (~36,000 km) | Japan + APAC | up to centimeters | Navigation (add-on) |
| NavIC (India) | 7 | GEO / IGSO (~36,000 km) | India (+1500 km) | < 20 m | Navigation |
| Starlink (USA) | ~6750 | LEO (~550 km) | Global | — | Communication (Internet) |
| OneWeb (Great Britain) | 648 | LEO (~1200 km) | Global | — | Communication (Internet) |
As can be seen from the table, satellite navigation and communication systems are designed for different tasks, which determines their design and parameters.
Global navigation systems (GPS, Galileo, BeiDou) have average orbits of ~20 thousand kilometers and a relatively small number of satellites (about 24-35) to cover the entire globe. At this altitude, one satellite “sees” most of the Earth’s surface, so ~30 satellites are enough to have several of them above the horizon at the same time at any point on the planet. This is the optimal balance between the number of satellites and their coverage. The accuracy of these systems for a mass user is about 3-5 m, but the European Galileo already provides meter and even sub-meter accuracy thanks to the latest technologies. China’s BeiDou is distinguished by the presence of geostationary satellites, which allow it to provide additional services over China (for example, short messages) and improve coverage reliability. It is important that modern receivers can use signals from several GNSS, so the end user benefits from synergy: for example, a phone simultaneously picks up GPS, Galileo, and BeiDou, getting more visible satellites and better position accuracy.
Regional navigation systems (NavIC, QZSS) cover limited areas, so they can get by with even fewer satellites or special orbits. India’s NavIC, consisting of 7 satellites, focuses on its region using geostationary platforms, which ensures that the satellites are constantly over India. Its accuracy (~10-20 m) is worse than GPS, but it is sufficient for regional needs, and most importantly, it is controlled by India, which is important for national security. Japan’s QZSS also has only 4-7 satellites, but due to special elliptical orbits, there is always at least one “overhead” in Japan, which significantly improves signal reception in cities and mountains. QZSS does not replace GPS, but works in conjunction with it: Japanese users receive GPS signals supplemented by local QZSS corrections, which allows them to achieve centimeter accuracy in geodesy and precision applications. Thus, regional systems complement global systems, sometimes providing redundancy and insurance against failure of the latter.
Satellite communication systems (Starlink, OneWeb) are fundamentally different from navigation systems. They do not determine coordinates but transmit large amounts of data. To minimize signal delays, these systems are located in low orbits (hundreds of kilometers). However, at such an altitude, one satellite covers a small area, so tens of thousands of satellites are needed for global coverage. SpaceX chose the lowest possible orbit of ~550 km and mass production of satellites – Starlink already has thousands of satellites and is constantly growing. Instead, OneWeb chose an orbit of ~1200 km – fewer satellites are needed (hundreds), but the signal delay time is slightly longer. Both systems provide high-speed Internet in areas where terrestrial communication is absent or unreliable, and complement the terrestrial telecom infrastructure from space. Unlike previously used geostationary communication satellites located at 36 thousand kilometers (e.g., TV broadcasting satellites or old VSAT systems), the new LEO constellations provide significantly lower latency and can provide higher bandwidth by distributing the load among thousands of devices. This opens up possibilities for the Internet of Things, connecting airplanes and ships, and providing Internet in crises (when terrestrial networks are damaged).
Both Starlink and OneWeb plan to further expand and upgrade their systems. Competition is driving rapid progress: the size and cost of user antennas are decreasing, and new generations of satellites with greater capabilities are being launched (for example, Starlink V2 is equipped with laser inter-satellite links for direct relay between vehicles). States are also closely monitoring such projects, as global satellite Internet networks raise issues of regulation, safety, and responsibility in space (in particular, avoiding space debris and preventing collisions in orbit).
Satellite navigation and communication systems are a prime example of how space technology serves the everyday needs of humanity. GPS, Galileo, BeiDou, and other navigation networks allow anyone with a receiver in their pocket to determine their location in seconds with an accuracy of several meters, whether on a busy city street or in the middle of the ocean. They provide accurate time measurement, which is the basis for the operation of financial systems and power grids. At the same time, satellite communications systems such as Starlink and OneWeb are rapidly developing, striving to provide access to high-speed Internet to every corner of the planet, overcoming digital inequality.
In the future, we can expect even greater integration of these systems into our lives. Multi-system navigators will use all available GNSS for maximum accuracy and reliability. Satellite Internet will become part of the global telecommunications infrastructure, complementing terrestrial 5G/6G networks and providing connectivity for autonomous vehicles, smart devices, and even entire cities. The diversity of systems also means greater resilience: if one network fails or is unavailable, another will take over. Thus, the constellation of satellites above us is not just shiny dots in the night sky, but also a guarantee that our modern world will remain interconnected, accurate, and informative in all circumstances.
