HOME

TheInfoList



OR:

Satellite Internet access is
Internet access Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Interne ...
provided through communication satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using to achieve downstream data speeds up to 506 
Mbit/s In telecommunications, data-transfer rate is the average number of bits ( bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mu ...
. In addition, new
satellite internet constellation A satellite internet constellation is a constellation of artificial satellites providing satellite internet service. In particular, the term has come to refer to a new generation of very large constellations (sometimes referred to as a megaco ...
s are being developed in
low-earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
to enable
low-latency Latency, from a general point of view, is a time delay between the cause and the effect of some physical change in the system being observed. Lag, as it is known in gaming circles, refers to the latency between the input to a simulation and ...
internet access from space.


History

Following the launch of the first satellite,
Sputnik 1 Sputnik 1 (; see § Etymology) was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the Soviet space program. It sent a radio signal back to Earth for ...
, by the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
in October 1957, the US successfully launched the
Explorer 1 Explorer 1 was the first satellite launched by the United States in 1958 and was part of the U.S. participation in the International Geophysical Year (IGY). The mission followed the first two satellites the previous year; the Soviet Union's S ...
satellite in 1958. The first commercial communications satellite was Telstar 1, built by
Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mul ...
and launched in July 1962. The idea of a
geosynchronous satellite A geosynchronous satellite is a satellite in geosynchronous orbit, with an orbital period the same as the Earth's rotation period. Such a satellite returns to the same position in the sky after each sidereal day, and over the course of a day tra ...
—one that could orbit the Earth above the equator and remain fixed by following the Earth's rotation—was first proposed by
Herman Potočnik Herman Potočnik (pseudonym Hermann Noordung; 22 December 1892 – 27 August 1929) was an ethnically Slovenian Austro-Hungarian Army officer, electrical engineer and astronautics theorist. He is regarded as a pioneer and visionary of modern space f ...
in 1928 and popularised by the
science fiction author This is a list of noted science-fiction authors (in alphabetical order): A *Dafydd ab Hugh (born 1960) * Alexander Abasheli (1884–1954) *Edwin Abbott Abbott (1838–1926) *Kōbō Abe (1924–1993) * Robert Abernathy (1924–1990) *Dan Ab ...
Arthur C. Clarke Sir Arthur Charles Clarke (16 December 191719 March 2008) was an English science-fiction writer, science writer, futurist, inventor, undersea explorer, and television series host. He co-wrote the screenplay for the 1968 film '' 2001: A Spac ...
in a paper in ''
Wireless World ''Electronics World'' (''Wireless World'', founded in 1913, and in September 1984 renamed ''Electronics & Wireless World'') is a technical magazine in electronics and RF engineering aimed at professional design engineers. It is produced monthly in ...
'' in 1945. The first satellite to successfully reach geostationary orbit was
Syncom3 Syncom (for "synchronous communication satellite") started as a 1961 NASA program for active geosynchronous communication satellites, all of which were developed and manufactured by the Space and Communications division of Hughes Aircraft Compa ...
, built by
Hughes Aircraft The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other pro ...
for
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
and launched on August 19, 1963. Succeeding generations of communications satellites featuring larger capacities and improved performance characteristics were adopted for use in television delivery, military applications and telecommunications purposes. Following the invention of the
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, p ...
and the World Wide Web, geostationary satellites attracted interest as a potential means of providing Internet access. A significant enabler of satellite-delivered Internet has been the opening up of the for satellites. In December 1993, Hughes Aircraft Co. filed with the
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...
for a license to launch the first Ka-band satellite,
Spaceway The Spaceway system was originally envisioned as a global Ka-band communications system by Hughes Electronics. When the project to build the system was taken over by Hughes Network Systems, a subsidiary of Hughes Electronics, it was transformed ...
. In 1995, the FCC issued a call for more Ka-band satellite applications, attracting applications from 15 companies. Among those were
EchoStar EchoStar Corporation is an American company, a worldwide provider of satellite communication and Internet services through its Hughes Network Systems and EchoStar Satellite Services business segments. EchoStar is based out of unincorporated Ar ...
,
Lockheed Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
, GE-Americom,
Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...
and KaStar Satellite, which later became
WildBlue Viasat Inc. is an American communications company based in Carlsbad, California, with additional operations across the United States and worldwide. Viasat is a provider of high-speed satellite broadband services and secure networking systems co ...
. Among prominent aspirants in the early-stage satellite Internet sector was
Teledesic Teledesic was a company founded in the 1990s to build a commercial broadband satellite internet constellation. Using low-Earth-orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/s and downlinks of up to 720 ...
, an ambitious and ultimately failed project funded in part by
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washi ...
that ended up costing more than $9 billion. Teledesic's idea was to create a
broadband In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one s ...
of hundreds of low-orbiting satellites in the Ka-band frequency, providing inexpensive Internet access with download speeds of up to 720 Mbit/s. The project was abandoned in 2003. Teledesic's failure, coupled with the bankruptcy filings of the satellite communications providers Iridium Communications Inc. and
Globalstar Globalstar, Inc. is an American satellite communications company that operates a low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications. The Globalstar second-generation constellation consists of 24 lo ...
, dampened marketplace enthusiasm for satellite Internet development. The first Internet-ready satellite for consumers was launched in September 2003. In 2004, with the launch of Anik F2, the first high throughput satellite, a class of next-generation satellites providing improved capacity and bandwidth became operational. More recently, high throughput satellites such as ViaSat's ViaSat-1 satellite in 2011 and HughesNet's Jupiter in 2012 have achieved further improvements, elevating downstream data rates from 1–3 Mbit/s up to 12–15Mbit/s and beyond. Internet access services tied to these satellites are targeted largely to rural residents as an alternative to Internet service via dial-up, ADSL or classic FSSes. In 2013 the first four satellites of the
O3b O3b is a satellite constellation in Medium Earth orbit (MEO) owned and operated by SES, and designed to provide low-latency broadband connectivity to remote locations for mobile network operators and internet service providers, maritime, aviat ...
constellation were launched into medium Earth orbit (MEO) to provide internet access to the "other three billion" people without stable internet access at that time. Over the next six years, 16 further satellites joined the constellation, now owned and operated by SES. Since 2014, a rising number of companies announced working on internet access using
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one s ...
s in
low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
.
SpaceX Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal o ...
,
OneWeb OneWeb (legally Network Access Associates Ltd) is a communications company that aims to build broadband satellite Internet services. The company is headquartered in London, and has offices in Virginia, US and a satellite manufacturing facility ...
and
Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...
all plan to launch more than 1000 satellites each. OneWeb alone raised $1.7 billion by February 2017 for the project, and SpaceX raised over one billion in the first half of 2019 alone for their service called
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
and expected more than $30 billion in revenue by 2025 from its satellite constellation. Many planned constellations employ
laser communication Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. "Free space" means air, outer space, vacuum, or ...
for inter-satellite links to effectively create a space-based
internet backbone The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer networks and core routers of the Internet. These data routes are hosted by commercial, government, academic and other high- ...
. In September 2017, SES announced the next generation of O3b satellites and service, named O3b mPOWER. The constellation of 11 MEO satellites will deliver 10 terabits of capacity globally through 30,000 spot beams for broadband internet services. The O3b mPOWER satellites are scheduled to launch 2022-2024 and the initial service start in Q3 2023. As of 2017, airlines such as Delta and
American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...
have been introducing satellite internet as a means of combating limited bandwidth on airplanes and offering passengers usable internet speeds.


Companies and market


United States

Companies providing home internet service in the United States of America include
ViaSat Viasat may refer to: *Viasat (American company) (founded 1986) *Viasat (Nordic television service) (founded 1991) * Danish 1st Division, officially Viasat Divisionen, second-highest football league in Denmark * Viasat Cup, 2006 Danish football tour ...
, through its
Exede Viasat may refer to: *Viasat (American company) (founded 1986) *Viasat (Nordic television service) (founded 1991) * Danish 1st Division, officially Viasat Divisionen, second-highest football league in Denmark * Viasat Cup, 2006 Danish football tour ...
brand,
EchoStar EchoStar Corporation is an American company, a worldwide provider of satellite communication and Internet services through its Hughes Network Systems and EchoStar Satellite Services business segments. EchoStar is based out of unincorporated Ar ...
, through subsidiary HughesNet, and
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
.


United Kingdom

In the United Kingdom, companies providing satellite Internet access include Konnect, Broadband Everywhere and Freedomsat.


Function

Satellite Internet generally relies on three primary components: a satellite historically in
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
(or GEO) but now increasingly in
Low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
(LEO) or
Medium Earth orbit A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
MEO) a number of ground stations known as gateways that relay Internet data to and from the satellite via radio waves (
microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...
), and further ground stations to serve each subscriber, with a small antenna and
transceiver In radio communication, a transceiver is an electronic device which is a combination of a radio ''trans''mitter and a re''ceiver'', hence the name. It can both transmit and receive radio waves using an antenna, for communication purposes. Thes ...
. Other components of a satellite Internet system include a
modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...
at the user end which links the user's network with the transceiver, and a centralized network operations centre (NOC) for monitoring the entire system. Working in concert with a broadband gateway, the satellite operates a Star network topology where all network communication passes through the network's hub processor, which is at the centre of the star. With this configuration, the number of ground stations that can be connected to the hub is virtually limitless.


Satellite

Marketed as the centre of the new broadband satellite networks are a new generation of high-powered GEO satellites positioned above the equator, operating in Ka-band (18.3–30 GHz) mode. These new purpose-built satellites are designed and optimized for broadband applications, employing many narrow spot beams, which target a much smaller area than the broad beams used by earlier communication satellites. This spot beam technology allows satellites to reuse assigned bandwidth multiple times which can enable them to achieve much higher overall capacity than conventional broad beam satellites. The spot beams can also increase performance and consequential capacity by focusing more power and increased receiver sensitivity into defined concentrated areas. Spot beams are designated as one of two types: subscriber spot beams, which transmit to and from the subscriber-side terminal, and gateway spot beams, which transmit to/from a service provider ground station. Note that moving off the tight footprint of a spotbeam can degrade performance significantly. Also, spotbeams can make the use of other significant new technologies impossible, including 'Carrier in
Carrier Carrier may refer to: Entertainment * ''Carrier'' (album), a 2013 album by The Dodos * ''Carrier'' (board game), a South Pacific World War II board game * ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...
' modulation. In conjunction with the satellite's spot-beam technology, a bent-pipe architecture has traditionally been employed in the network in which the satellite functions as a bridge in space, connecting two communication points on the ground. The term "bent-pipe" is used to describe the shape of the data path between sending and receiving antennas, with the satellite positioned at the point of the bend. Simply put, the satellite's role in this network arrangement is to relay signals from the end user's terminal to the ISP's gateways, and back again without processing the signal at the satellite. The satellite receives, amplifies, and redirects a carrier on a specific radio frequency through a signal path called a transponder. Some
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one s ...
s in LEO such as
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
and the proposed
Telesat Telesat, formerly Telesat Canada, is a Canadian satellite communications company founded on May 2, 1969. The company is headquartered in Ottawa. History Telesat began as Telesat Canada, a Canadian Crown corporation created by an Act of Pa ...
constellation will employ
laser communication Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. "Free space" means air, outer space, vacuum, or ...
equipment for high-throughput optical inter-satellite links. The interconnected satellites allow for direct routing of user data from satellite to satellite and effectively create a space-based
optical mesh network An optical mesh network is a type of optical telecommunications network employing wired fiber-optic communication or wireless free-space optical communication in a mesh network architecture. Most optical mesh networks use fiber-optic communicatio ...
that will enable seamless network management and continuity of service. The satellite has its own set of antennas to receive communication signals from Earth and to transmit signals to their target location. These antennas and transponders are part of the satellite's "payload", which is designed to receive and transmit signals to and from various places on Earth. What enables this transmission and reception in the payload transponders is a repeater subsystem (RF (radio frequency) equipment) used to change frequencies, filter, separate, amplify and group signals before routing them to their destination address on Earth. The satellite's high-gain receiving antenna passes the transmitted data to the transponder which filters, translates and amplifies them, then redirects them to the transmitting antenna on board. The signal is then routed to a specific ground location through a channel known as a carrier. Beside the payload, the other main component of a communications satellite is called the bus, which comprises all equipment required to move the satellite into position, supply power, regulate equipment temperatures, provide health and tracking information, and perform numerous other operational tasks.


Gateways

Along with dramatic advances in satellite technology over the past decade, ground equipment has similarly evolved, benefiting from higher levels of integration and increasing processing power, expanding both capacity and performance boundaries. The Gateway—or Gateway Earth Station (its full name)—is also referred to as a ground station, teleport or hub. The term is sometimes used to describe just the antenna dish portion, or it can refer to the complete system with all associated components. In short, the gateway receives radio wave signals from the satellite on the last leg of the return or upstream payload, carrying the request originating from the end-user's site. The satellite modem at the gateway location demodulates the incoming signal from the outdoor antenna into IP packets and sends the packets to the local network. Access server/gateways manage traffic transported to/from the Internet. Once the initial request has been processed by the gateway's servers, sent to and returned from the Internet, the requested information is sent back as a forward or downstream payload to the end-user via the satellite, which directs the signal to the subscriber terminal. Each Gateway provides the connection to the Internet backbone for the gateway beam(s) it serves. The system of gateways comprising the satellite ground system provides all network services for satellite and corresponding terrestrial connectivity. Each gateway provides a multiservice access network for subscriber terminal connections to the Internet. In the continental United States, because it is north of the equator, all gateway and subscriber dish antenna must have an unobstructed view of the southern sky. Because of the satellite's geostationary orbit, the gateway antenna can stay pointed at a fixed position.


Antenna dish and modem

For the customer-provided equipment (i.e. PC and router) to access the broadband satellite network, the customer must have additional physical components installed:


Outdoor unit (ODU)

At the far end of the outdoor unit is typically a small (2–3-foot, 60–90 cm diameter), reflective dish-type radio antenna. The VSAT antenna must also have an unobstructed view of the sky to allow for proper line-of-sight (L-O-S) to the satellite. There are four physical characteristic settings used to ensure that the antenna is configured correctly at the satellite, which are:
azimuth An azimuth (; from ar, اَلسُّمُوت, as-sumūt, the directions) is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north. Mathematical ...
, elevation, polarization, and skew. The combination of these settings gives the outdoor unit a L-O-S to the chosen satellite and makes data transmission possible. These parameters are generally set at the time the equipment is installed, along with a beam assignment (Ka-band only); these steps must all be taken prior to the actual activation of service. Transmit and receive components are typically mounted at the focal point of the antenna which receives/sends data from/to the satellite. The main parts are: * Feed – This assembly is part of the VSAT receive and transmit chain, which consists of several components with different functions, including the feed horn at the front of the unit, which resembles a funnel and has the task of focusing the satellite microwave signals across the surface of the dish reflector. The feed horn both receives signals reflected off the dish's surface and transmits outbound signals back to the satellite. *
Block upconverter {{Antennas, components A block upconverter (BUC) is used in the transmission (uplink) of satellite signals. It converts a band of frequencies from a lower frequency to a higher frequency. Modern BUCs convert from the L band to Ku band, C band ...
(BUC) – This unit sits behind the feed horn and may be part of the same unit, but a larger (higher wattage) BUC could be a separate piece attached to the base of the antenna. Its job is to convert the signal from the modem to a higher frequency and amplify it before it is reflected off the dish and towards the satellite. *
Low-noise block downconverter A low-noise block downconverter (LNB) is the receiving device mounted on satellite dishes used for satellite TV reception, which collects the radio waves from the dish and converts them to a signal which is sent through a cable to the receiver ...
(LNB) – This is the receiving element of the terminal. The LNB's job is to amplify the received satellite radio signal bouncing off the dish and filter out the noise, which is any signal not carrying valid information. The LNB passes the amplified, filtered signal to the satellite modem at the user's location.


Indoor unit (IDU)

The satellite
modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...
serves as an interface between the outdoor unit and customer-provided equipment (i.e. PC, router) and controls satellite transmission and reception. From the sending device (computer, router, etc.) it receives an input
bitstream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...
and converts or modulates it into radio waves, reversing that order for incoming transmissions, which is called
demodulation Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulate ...
. It provides two types of connectivity: * Coaxial cable (COAX) connectivity to the satellite antenna. The cable carrying electromagnetic satellite signals between the modem and the antenna generally is limited to be no more than 150 feet in length. *
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
connectivity to the computer, carrying the customer's data packets to and from the Internet content servers. Consumer grade satellite modems typically employ either the
DOCSIS Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable televisio ...
or
WiMAX Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options. The WiMAX ...
telecommunication standard to communicate with the assigned gateway.


Challenges and limitations


Signal latency

Latency (commonly referred to as "ping time") is the delay between requesting data and the receipt of a response, or in the case of one-way communication, between the actual moment of a signal's broadcast and the time it is received at its destination. A radio signal takes about 120 milliseconds to reach a geostationary satellite and then 120 milliseconds to reach the ground station, so nearly 1/4 of a second overall. Typically, during perfect conditions, the physics involved in satellite communications account for approximately 550 milliseconds of latency round-trip time. The longer latency is the primary difference between a standard terrestrial-based network and a geostationary satellite-based network. The round-trip latency of a geostationary satellite communications network can be more than 12 times that of a terrestrial based network. Satellite latency can be detrimental to especially time-sensitive applications such as on-line gaming (although it only seriously affects the likes of
first-person shooter First-person shooter (FPS) is a sub-genre of shooter video games centered on gun and other weapon-based combat in a first-person perspective, with the player experiencing the action through the eyes of the protagonist and controlling the p ...
s while many MMOGs can operate well over satellite Internet), but IPTV is typically a
simplex In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions. The simplex is so-named because it represents the simplest possible polytope in any given dimension. ...
operation (one-way transmission) and latency is not a critical factor for video transmission. The effects of this delay may be mitigated using data compression, TCP-acceleration, and HTTP pre-fetching.


Geostationary orbits

A
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
(or geostationary Earth orbit/GEO) is a geosynchronous orbit directly above the Earth's equator (0° latitude), with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero (i.e. a "circular orbit"). An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers. Launchers often place communications satellites and weather satellites in geostationary orbits, so that the satellite antennas that communicate with them do not have to move to track them, but can point permanently at the position in the sky where the satellites stay. Due to the constant 0° latitude and circularity of geostationary orbits, satellites in GEO differ in location by longitude only. Compared to ground-based communication, all geostationary satellite communications experience higher latency due to the signal having to travel to a satellite in geostationary orbit and back to Earth again. Even at the
speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit fo ...
(about 300,000 km/s or 186,000 miles per second), this delay can appear significant. If all other signaling delays could be eliminated, it still takes a radio signal about 250 milliseconds (ms), or about a quarter of a second, to travel to the satellite and back to the ground. The absolute minimum total amount of delay varies, due to the satellite staying in one place in the sky, while ground-based users can be directly below (with a roundtrip latency of 239.6 ms), or far to the side of the planet near the horizon (with a roundtrip latency of 279.0 ms). For an Internet packet, that delay is doubled before a reply is received. That is the theoretical minimum. Factoring in other normal delays from network sources gives a typical one-way connection latency of 500–700 ms from the user to the ISP, or about 1,000–1,400 ms latency for the total round-trip time (RTT) back to the user. This is more than most dial-up users experience at typically 150–200 ms total latency, and much higher than the typical 15–40 ms latency experienced by users of other high-speed Internet services, such as cable or
VDSL Very high-speed digital subscriber line (VDSL) and very high-speed digital subscriber line 2 (VDSL2) are digital subscriber line (DSL) technologies providing data transmission faster than the earlier standards of asymmetric digital subscriber line ...
. For geostationary satellites, there is no way to eliminate latency, but the problem can be somewhat mitigated in Internet communications with
TCP acceleration The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonl ...
features that shorten the apparent round trip time (RTT) per packet by splitting ("spoofing") the feedback loop between the sender and the receiver. Certain acceleration features are often present in recent technology developments embedded in satellite Internet equipment. Latency also impacts the initiation of secure Internet connections such as
SSL SSL may refer to: Entertainment * RoboCup Small Size League, robotics football competition * ''Sesame Street Live'', a touring version of the children's television show * StarCraft II StarLeague, a Korean league in the video game Natural language ...
which require the exchange of numerous pieces of data between web server and web client. Although these pieces of data are small, the multiple round-trips involved in the handshake produce long delays compared to other forms of Internet connectivity, as documented by Stephen T. Cobb in a 2011 report published by the Rural Mobile and Broadband Alliance. This annoyance extends to entering and editing data using some Software as a Service or
SaaS Software as a service (SaaS ) is a software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted. SaaS is also known as "on-demand software" and Web-based/Web-hosted software. SaaS is co ...
applications as well as in other forms of online work. Functions like live interactive access to a distant computer—such as
virtual private network A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The b ...
s can be affected by the high latency. Many TCP protocols were not designed to work in high-latency environments.


Medium and Low Earth Orbits

Medium Earth orbit (MEO) and low Earth orbit (LEO) satellite constellations do not have such long delays, as the satellites are closer to the ground. For example: * The current LEO constellations of
Globalstar Globalstar, Inc. is an American satellite communications company that operates a low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications. The Globalstar second-generation constellation consists of 24 lo ...
and
Iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density o ...
satellites have delays of less than 40 ms round trip, but their throughput is less than broadband at 64 kbit/s per channel. The Globalstar constellation orbits 1,420 km above the Earth and Iridium orbits at 670 km altitude. * The
O3b O3b is a satellite constellation in Medium Earth orbit (MEO) owned and operated by SES, and designed to provide low-latency broadband connectivity to remote locations for mobile network operators and internet service providers, maritime, aviat ...
constellation orbits at 8,062 km, with RTT latency of approximately 125 ms. The network is also designed for much higher throughput with links well in excess of 1 Gbit/s (Gigabits per second). The forthcoming O3b mPOWER constellation shares the same orbit and will deliver from 50Mbps to multiple gigabits per second to a single user. * The
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
satellites orbit at 550 km altitude, with an average RTT latency of 45 ms in 2021. Unlike geostationary satellites, LEO and MEO satellites do not stay in a fixed position in the sky and from a lower altitude they can "see" a smaller area of the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
, and so continuous widespread access requires a
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...
of many satellites (low-Earth orbits needing more satellites than medium-Earth orbits) with complex constellation management to switch data transfer between satellites and keep the connection to a customer, and tracking by the ground stations.''Large LEO satellite constellations: Will it be different this time?''
McKinsey & Company, 4 May 2020, Accessed 25 April 2021
MEO satellites require higher power transmissions than LEO to achieve the same signal strength at the ground station but their higher altitude also provides less orbital overcrowding, and their slower orbit speed reduces both
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who ...
and the size and complexity of the constellation required. Tracking of the moving satellites is usually undertaken in one of three ways, using: * more diffuse or completely omnidirectional ground antennas capable of communicating with one or more satellites visible in the sky at the same time, but at significantly higher transmit power than fixed geostationary dish antennas (due to the lower gain), and with much poorer signal-to-noise ratios for receiving the signal * motorized antenna mounts with high-gain, narrow beam antennas tracking individual satellites *
phased array In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving th ...
antennas that can steer the beam electronically, together with software that can predict the path of each satellite in the constellation. In May 2022, Kazakhstani mobile network operator,
Kcell Kcell (KASE: KCEL) is the Cellular Communication Operator in Kazakhstan, part of Kazakhtelecom. The company was founded in 1998 and provides cellular services under the Kcell brand, which is mainly focused on the corporate segment, and Activ, ...
, and satellite owner and operator, SES used SES's
O3b O3b is a satellite constellation in Medium Earth orbit (MEO) owned and operated by SES, and designed to provide low-latency broadband connectivity to remote locations for mobile network operators and internet service providers, maritime, aviat ...
MEO
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one s ...
to demonstrate that MEO satellites could be used to provide high-speed mobile internet to remote regions of Kazakhstan for reliable video calling, conferencing and streaming, and web browsing, with a latency five times lower than on the existing platform based on
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
satellites.


Ultralight atmospheric aircraft as satellites

A proposed alternative to relay satellites is a special-purpose
solar-powered Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an electric current using the photovoltaic ef ...
ultralight Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...
aircraft, which would fly along a circular path above a fixed ground location, operating under autonomous computer control at a height of approximately 20,000 meters. For example, the United States
Defense Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...
Vulture A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...
project envisaged an ultralight aircraft capable of station-keeping over a fixed area for a period of up to five years, and able to provide both continuous surveillance to ground assets as well as to service extremely low-latency communications networks. This project was cancelled in 2012 before it became operational. Onboard batteries would charge during daylight hours through solar panels covering the wings, and would provide power to the plane during night. Ground-based satellite internet dishes would relay signals to and from the aircraft, resulting in a greatly reduced round-trip signal latency of only 0.25 milliseconds. The planes could potentially run for long periods without refueling. Several such schemes involving various types of aircraft have been proposed in the past.


Interference

Satellite communications are affected by moisture and various forms of precipitation (such as rain or snow) in the signal path between end users or ground stations and the satellite being utilized. This interference with the signal is known as ''rain fade''. The effects are less pronounced on the lower frequency 'L' and 'C' bands, but can become quite severe on the higher frequency 'Ku' and 'Ka' band. For satellite Internet services in tropical areas with heavy rain, use of the C band (4/6 GHz) with a circular polarisation satellite is popular. Satellite communications on the Ka band (19/29 GHz) can use special techniques such as large ''rain margins'', ''adaptive uplink power control'' and ''reduced bit rates'' during precipitation. ''Rain margins'' are the extra communication link requirements needed to account for signal degradations due to moisture and precipitation, and are of acute importance on all systems operating at frequencies over 10 GHz. The amount of time during which service is lost can be reduced by increasing the size of the satellite communication dish so as to gather more of the satellite signal on the downlink and also to provide a stronger signal on the uplink. In other words, increasing antenna gain through the use of a larger parabolic reflector is one way of increasing the overall channel gain and, consequently, the signal-to-noise (S/N) ratio, which allows for greater signal loss due to rain fade without the S/N ratio dropping below its minimum threshold for successful communication. Modern consumer-grade dish antennas tend to be fairly small, which reduces the rain margin or increases the required satellite downlink power and cost. However, it is often more economical to build a more expensive satellite and smaller, less expensive consumer antennas than to increase the consumer antenna size to reduce the satellite cost. Large commercial dishes of 3.7 m to 13 m diameter can be used to achieve increased rain margins and also to reduce the cost per bit by allowing for more efficient modulation codes. Alternately, larger aperture antennae can require less power from the satellite to achieve acceptable performance. Satellites typically use
photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...
solar power, so there is no expense for the energy itself, but a more powerful satellite will require larger, more powerful solar panels and electronics, often including a larger transmitting antenna. The larger satellite components not only increase materials costs but also increase the weight of the satellite, and in general, the cost to launch a satellite into an orbit is directly proportional to its weight. (In addition, since satellite launch vehicles .e. rocketshave specific payload size limits, making parts of the satellite larger may require either more complex folding mechanisms for parts of the satellite like solar panels and high-gain antennas, or upgrading to a more expensive launch vehicle that can handle a larger payload.) Modulated carriers can be dynamically altered in response to rain problems or other link impairments using a process called adaptive coding and modulation, or "ACM". ACM allows the bit rates to be increased substantially during normal clear sky conditions, increasing the number of bits per Hz transmitted, and thus reducing overall cost per bit. Adaptive coding requires some sort of a return or feedback channel which can be via any available means, satellite or terrestrial.


Line of sight

Two objects are said to be within line of sight if a straight line between the objects can be connected without any interference, such as a mountain. An object beyond the horizon is below the line of sight and, therefore, can be difficult to communicate with. Typically a completely clear line of sight between the dish and the satellite is required for the system to work optimally. In addition to the signal being susceptible to absorption and scattering by moisture, the signal is similarly impacted by the presence of trees and other vegetation in the path of the signal. As the radio frequency decreases, to below 900 MHz, penetration through vegetation increases, but most satellite communications operate above 2 GHz making them sensitive to even minor obstructions such as tree foliage. A dish installation in the winter must factor in plant foliage growth that will appear in the spring and summer.


Fresnel zone

Even if there is a direct line of sight between the transmitting and receiving antenna, reflections from objects near the path of the signal can decrease apparent signal power through phase cancellations. Whether and how much signal is lost from a reflection is determined by the location of the object in the Fresnel zone of the antennas.


Two-way satellite-only communication

Home or consumer grade two-way satellite Internet service involves both sending and receiving data from a remote
very-small-aperture terminal A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 1 ...
(VSAT) via satellite to a hub
telecommunications port A ground station, Earth station, or Earth terminal is a terrestrial radio station designed for extraplanetary telecommunication with spacecraft (constituting part of the ground segment of the spacecraft system), or reception of radio waves fro ...
(teleport), which then relays data via the terrestrial Internet. The satellite dish at each location must be precisely pointed to avoid interference with other satellites. At each VSAT site the uplink frequency, bit rate and power must be accurately set, under control of the service provider hub. There are several types of two way satellite Internet services, including
time-division multiple access Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession ...
(TDMA) and single channel per carrier (SCPC). Two-way systems can be simple
VSAT A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 1 ...
terminals with a 60–100 cm dish and output power of only a few watts intended for consumers and small business or larger systems which provide more bandwidth. Such systems are frequently marketed as "satellite broadband" and can cost two to three times as much per month as land-based systems such as
ADSL Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ...
. The
modems A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carr ...
required for this service are often proprietary, but some are compatible with several different providers. They are also expensive, costing in the range of US$600 to $2000. The two-way "iLNB" used on the
SES Broadband SES Broadband (previously ASTRA2Connect) is a two-way satellite broadband Internet service available across Europe, which launched in March 2007, and uses the Astra series of geostationary satellites. SES Broadband is owned and operated by SE ...
terminal dish has a transmitter and single-polarity receive LNB, both operating in the . Pricing for SES Broadband modems range from €299 to €350. These types of system are generally unsuitable for use on moving vehicles, although some dishes may be fitted to an automatic pan and tilt mechanism to continuously re-align the dish—but these are more expensive. The technology for SES Broadband was delivered by a Belgian company called Newtec.


Bandwidth

Consumer satellite Internet customers range from individual home users with one PC to large remote business sites with several hundred PCs. Home users tend to use shared satellite capacity to reduce the cost, while still allowing high peak bit rates when congestion is absent. There are usually restrictive time-based bandwidth allowances so that each user gets their fair share, according to their payment. When a user exceeds their allowance, the company may slow down their access, deprioritise their traffic or charge for the excess bandwidth used. For consumer satellite Internet, the allowance can typically range from 200  MB per day to 25  GB per month.HughesNet Fair Access Policy FAQ
/ref> A shared download carrier may have a bit rate of 1 to 40 Mbit/s and be shared by up to 100 to 4,000 end users. The uplink direction for shared user customers is normally
time-division multiple access Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession ...
(TDMA), which involves transmitting occasional short packet bursts in between other users (similar to how a cellular phone shares a cell tower). Each remote location may also be equipped with a telephone modem; the connections for this are as with a conventional dial-up ISP. Two-way satellite systems may sometimes use the modem channel in both directions for data where latency is more important than bandwidth, reserving the satellite channel for download data where bandwidth is more important than latency, such as for
file transfer File transfer is the transmission of a computer file through a communication channel from one computer system to another. Typically, file transfer is mediated by a communications protocol. In the history of computing, numerous file transfer protoco ...
s. In 2006, the
European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...
sponsored the
UNIC Project Unic was a French manufacturer founded in 1905, and active as an automobile producer until July 1938. After this the company continued to produce commercial vehicles, retaining its independence for a further fourteen years before being purcha ...
which aimed to develop an end-to-end scientific test bed for the distribution of new broadband interactive TV-centric services delivered over low-cost two-way satellite to actual end-users in the home. The UNIC architecture employs
DVB-S2 Digital Video Broadcasting - Satellite - Second Generation (DVB-S2) is a digital television broadcast standard that has been designed as a successor for the popular DVB-S system. It was developed in 2003 by the Digital Video Broadcasting Projec ...
standard for downlink and
DVB-RCS DVB-RCS is an acronym for Digital Video Broadcasting - Return Channel via Satellite or (''Return channel over system''). It is a specification for an interactive on-demand multimedia satellite communication system formulated in 1999 by the DVB cons ...
standard for uplink. Normal VSAT dishes (1.2–2.4 m diameter) are widely used for VoIP phone services. A voice call is sent by means of packets via the satellite and Internet. Using coding and compression techniques the bit rate needed per call is only 10.8 kbit/s each way.


Portable satellite Internet


Portable satellite modem

These usually come in the shape of a self-contained flat rectangular box that needs to be pointed in the general direction of the satellite—unlike VSAT the alignment need not be very precise and the modems have built in signal strength meters to help the user align the device properly. The modems have commonly used connectors such as
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
or
Universal Serial Bus Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
(USB). Some also have an integrated
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
transceiver and double as a satellite phone. The modems also tend to have their own batteries so they can be connected to a
laptop A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
without draining its battery. The most common such system is INMARSAT's BGAN—these terminals are about the size of a
briefcase A briefcase is a narrow hard-sided box-shaped bag or case used mainly for carrying papers and equipped with a handle. Lawyers commonly use briefcases to carry briefs to present to a court, hence the name. Businesspeople and other white collar pr ...
and have near-symmetric connection speeds of around 350–500 kbit/s. Smaller modems exist like those offered by
Thuraya Thuraya ( ar, الثريا, Gulf Arabic pron.: ; from the Arabic name for the constellation of the Pleiades, ''Thurayya'') is a United Arab Emirates-based regional mobile-satellite service (MSS) provider. The company operates two geosynchronous ...
but only connect at 444 kbit/s in a limited coverage area. INMARSAT now offer the IsatHub, a paperback book sized satellite modem working in conjunction with the users mobile phone and other devices. The cost has been reduced to $3 per MB and the device itself is on sale for about $1300. Using such a modem is extremely expensive—data transfer costs between $5 and $7 per
megabyte The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes o ...
. The modems themselves are also expensive, usually costing between $1,000 and $5,000.


Internet via satellite phone

For many years
satellite phone A satellite telephone, satellite phone or satphone is a type of mobile phone that connects to other phones or the telephone network by radio through orbiting satellites instead of terrestrial cell sites, as cellphones do. The advantage of a sa ...
s have been able to connect to the Internet. Bandwidth varies from about 2400
bit/s In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...
for Iridium network satellites and
ACeS ACeS (PT Asia Cellular Satellite) was a regional satellite telecommunications company based in Jakarta, Indonesia. It offered GSM-like satellite telephony services to Asian market. The coverage area included Indonesia, Malaysia, Thailand, Philip ...
based phones to 15 kbit/s
upstream Upstream may refer to: * Upstream (bioprocess) * ''Upstream'' (film), a 1927 film by John Ford * Upstream (networking) * ''Upstream'' (newspaper), a newspaper covering the oil and gas industry * Upstream (petroleum industry) * Upstream (software ...
and 60 kbit/s
downstream Downstream may refer to: * Downstream (bioprocess) * Downstream (manufacturing) * Downstream (networking) * Downstream (software development) * Downstream (petroleum industry) * Upstream and downstream (DNA), determining relative positions on DNA ...
for
Thuraya Thuraya ( ar, الثريا, Gulf Arabic pron.: ; from the Arabic name for the constellation of the Pleiades, ''Thurayya'') is a United Arab Emirates-based regional mobile-satellite service (MSS) provider. The company operates two geosynchronous ...
handsets. Globalstar also provides Internet access at 9600 bit/s—like Iridium and ACeS a
dial-up Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telepho ...
connection is required and is billed per minute, however both
Globalstar Globalstar, Inc. is an American satellite communications company that operates a low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications. The Globalstar second-generation constellation consists of 24 lo ...
and Iridium are planning to launch new satellites offering always-on data services at higher rates. With Thuraya phones the 9,600 bit/s dial-up connection is also possible, the 60 kbit/s service is always-on and the user is billed for data transferred (about $5 per
megabyte The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes o ...
). The phones can be connected to a laptop or other computer using a USB or
RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' ('' data terminal equipment'') suc ...
interface. Due to the low bandwidths involved it is extremely slow to browse the web with such a connection, but useful for sending email,
Secure Shell The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution. SSH applications are based ...
data and using other low-bandwidth protocols. Since satellite phones tend to have
omnidirectional antenna In radio communication, an omnidirectional antenna is a class of antenna which radiates equal radio power in all directions perpendicular to an axis (azimuthal directions), with power varying with angle to the axis ( elevation angle), declining ...
s no alignment is required as long as there is a line of sight between the phone and the satellite.


One-way receive, with terrestrial transmit

One-way terrestrial return satellite Internet systems are used with conventional
dial-up Internet access Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telepho ...
, with outbound (
upstream Upstream may refer to: * Upstream (bioprocess) * ''Upstream'' (film), a 1927 film by John Ford * Upstream (networking) * ''Upstream'' (newspaper), a newspaper covering the oil and gas industry * Upstream (petroleum industry) * Upstream (software ...
) data traveling through a telephone
modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...
, but
downstream Downstream may refer to: * Downstream (bioprocess) * Downstream (manufacturing) * Downstream (networking) * Downstream (software development) * Downstream (petroleum industry) * Upstream and downstream (DNA), determining relative positions on DNA ...
data sent via satellite at a higher rate. In the U.S., an FCC license is required for the uplink station only; no license is required for the users. Another type of 1-way satellite Internet system uses
General Packet Radio Service General Packet Radio Service (GPRS) is a packet oriented mobile data standard on the 2G and 3G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Ins ...
(GPRS) for the back-channel. Using standard GPRS or Enhanced Data Rates for GSM Evolution (EDGE), costs are reduced for higher effective rates if the upload volume is very low, and also because this service is not per-time charged, but charged by volume uploaded. GPRS as return improves mobility when the service is provided by a satellite that transmits in the field of 100-200 kW. Using a 33 cm wide satellite dish, a notebook and a normal GPRS equipped GSM phone, users can get mobile satellite broadband.


System components

The transmitting station has two components, consisting of a high speed Internet connection to serve many customers at once, and the satellite uplink to broadcast requested data to the customers. The ISP's routers connect to proxy servers which can enforce quality of service (QoS) bandwidth limits and guarantees for each customer's traffic. Often, nonstandard IP stacks are used to address the latency and asymmetry problems of the satellite connection. As with one-way receive systems, data sent over the satellite link is generally also encrypted, as otherwise it would be accessible to anyone with a satellite receiver. Many IP-over-satellite implementations use paired proxy servers at both endpoints so that certain communications between clients and servers need not to accept the latency inherent in a satellite connection. For similar reasons, there exist special
Virtual private network A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The b ...
(VPN) implementations designed for use over satellite links because standard VPN software cannot handle the long packet travel times. Upload speeds are limited by the user's dial-up modem, while download speeds can be very fast compared to dial-up, using the modem only as the control channel for packet acknowledgement. Latency is still high, although lower than full two-way geostationary satellite Internet, since only half of the data path is via satellite, the other half being via the terrestrial channel.


One-way broadcast, receive only

One-way broadcast satellite Internet systems are used for
Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. ...
(IP)
broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...
-based data, audio and video distribution. In the U.S., a
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...
(FCC) license is required only for the uplink station and no license is required for users. Note that most Internet protocols will not work correctly over one-way access, since they require a return channel. However, Internet content such as web pages can still be distributed over a one-way system by "pushing" them out to local storage at end user sites, though full interactivity is not possible. This is much like TV or radio content which offers little user interface. The broadcast mechanism may include compression and error correction to help ensure the one-way broadcast is properly received. The data may also be rebroadcast periodically, so that receivers that did not previously succeed will have additional chances to try downloading again. The data may also be encrypted, so that while anyone can receive the data, only certain destinations are able to actually decode and use the broadcast data. Authorized users only need to have possession of either a short
decryption key In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can deci ...
or an automatic rolling code device that uses its own highly accurate independent timing mechanism to decrypt the data.


System hardware components

Similar to one-way terrestrial return, satellite Internet access may include interfaces to the
public switched telephone network The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...
for squawk box applications. An Internet connection is not required, but many applications include a
File Transfer Protocol The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and da ...
(FTP) server to queue data for broadcast.


System software components

Most one-way broadcast applications require custom programming at the remote sites. The software at the remote site must filter, store, present a selection interface to and display the data. The software at the transmitting station must provide access control, priority queuing, sending, and encapsulating of the data.


Services

Emerging commercial services in this area include: * Outernet
Satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one s ...
technology


Efficiency increases


2013 FCC report cites big jump in satellite performance

In its report released in February, 2013, the Federal Communications Commission noted significant advances in satellite Internet performance. The FCC's Measuring Broadband America report also ranked the major ISPs by how close they came to delivering on advertised speeds. In this category, satellite Internet topped the list, with 90% of subscribers seeing speeds at 140% or better than what was advertised.


Reducing satellite latency

Much of the slowdown associated with satellite Internet is that for each request, many roundtrips must be completed before any useful data can be received by the requester. Special IP stacks and proxies can also reduce latency through lessening the number of roundtrips, or simplifying and reducing the length of protocol headers. Optimization technologies include
TCP acceleration The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonl ...
,
HTTP The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide We ...
pre-fetching and DNS caching among many others. See the
Space Communications Protocol Specifications The Space Communications Protocol Specifications (SCPS) are a set of extensions to existing protocols and new protocols developed by the Consultative Committee for Space Data Systems (CCSDS) to improve performance of Internet protocols in space env ...
standard (SCPS), developed by NASA and adopted widely by commercial and military equipment and software providers in the market space.


Satellites launched

The
WINDS Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...
satellite was launched on February 23, 2008. The WINDS satellite is used to provide broadband Internet services to Japan and locations across the Asia-Pacific region. The satellite to provides a maximum speed of 155 Mbit/s down and 6 Mbit/s up to residences with a 45 cm aperture antenna and a 1.2 Gbit/s connection to businesses with a 5-meter antenna. It has reached the end of its design life expectancy. SkyTerra-1 was launched in mid-November 2010, providing North America, while
Hylas-1 HYLAS (or HYLAS-1) is a British satellite in geostationary orbit. HYLAS, which is an acronym for ''Highly Adaptable Satellite'', is a communications satellite and was launched by the European Ariane 5 launch vehicle from the Guyana Space Centre a ...
was launched in November 2010, targeting Europe. On December 26, 2010, Eutelsat's KA-SAT was launched. It covers the European continent with 80 spot beams—focused signals that cover an area a few hundred kilometers across Europe and the Mediterranean. Spot beams allow for frequencies to be effectively reused in multiple regions without interference. The result is increased capacity. Each of the spot beams has an overall capacity of 900 Mbit/s and the entire satellite will has a capacity of 70 Gbit/s. ViaSat-1 was launched Oct. 19, 2011 from Baikonur, Kazakhstan, offering 140 Gbit/s of total throughput capacity, through the Exede Internet service. Passengers aboard JetBlue Airways can use this service since 2015. The service has also been expanded to
United Airlines United Airlines, Inc. (commonly referred to as United), is a major American airline headquartered at the Willis Tower in Chicago, Illinois.
,
American Airlines American Airlines is a major US-based airline headquartered in Fort Worth, Texas, within the Dallas–Fort Worth metroplex. It is the largest airline in the world when measured by fleet size, scheduled passengers carried, and revenue passeng ...
,
Scandinavian Airlines Scandinavian Airlines, more commonly known and styled as SAS, is the flag carrier of Denmark, Norway, and Sweden. ''SAS'' is an abbreviation of the company's full name, Scandinavian Airlines System or legally Scandinavian Airlines System Denmar ...
,
Virgin America Virgin America Inc. was a low-cost U.S. airline that operated from 2007 until 2018, when it was acquired by Alaska Airlines. The airline primarily focused on operating low-fare service between cities on the West Coast and other major metropol ...
and
Qantas Qantas Airways Limited ( ) is the flag carrier of Australia and the country's largest airline by fleet size, international flights, and international destinations. It is the world's third-oldest airline still in operation, having been founde ...
. The
EchoStar XVII EchoStar XVII or EchoStar 17, also known as Jupiter 1, is an American geostationary high throughput communications satellite which is operated by Hughes Network Systems, a subsidiary of EchoStar. It is positioned in geostationary orbit at a lon ...
satellite was launched July 5, 2012 by Arianespace and was placed in its permanent geosynchronous orbital slot of 107.1° West longitude, servicing HughesNet. This Ka-band satellite has over 100 Gbit/s of throughput capacity. Since 2013, the
O3b satellite constellation O3b is a satellite constellation in Medium Earth orbit (MEO) owned and operated by SES S.A., SES, and designed to provide low-latency broadband connectivity to remote locations for mobile network operators and internet service providers, marit ...
claims an end-to-end round-trip latency of 238 ms for data services. In 2015 and 2016, the Australian Government launched two
satellites A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotop ...
to provide internet to regional Australians and residents of External Territories, such as
Norfolk Island Norfolk Island (, ; Norfuk: ''Norf'k Ailen'') is an external territory of Australia located in the Pacific Ocean between New Zealand and New Caledonia, directly east of Australia's Evans Head and about from Lord Howe Island. Together wit ...
and
Christmas Island Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the ...
.


Low Earth orbit

, around 2300 satellites have been launched for
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
and 400 for the
OneWeb satellite constellation OneWeb (legally Network Access Associates Ltd) is a communications company that aims to build broadband satellite Internet services. The company is headquartered in London, and has offices in Virginia, US and a satellite manufacturing facility ...
. SpaceX reported 250,000 users of its Starlink system.


In oceanography and in seismology

Satellite communications are used for data transmission, remote instrument diagnostics, for physical satellite and
oceanographic Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...
measurements from the sea surface (e.g.
sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mas ...
and
sea surface height Ocean surface topography or sea surface topography, also called ocean dynamic topography, are highs and lows on the ocean surface, similar to the hills and valleys of Earth's land surface depicted on a topographic map. These variations are ex ...
) to the
ocean floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
, and for seismological analyses.


See also

* Back-channel and return channel * DishNET (satellite Internet access in the United States) * HughesNet (formerly DIRECWAY) *
IP over DVB IP over DVB implies that Internet Protocol datagrams are distributed using some digital television system, for example DVB-H, DVB-T, DVB-S, DVB-C or their successors like DVB-S2. This may take the form of IP over MPEG, where the datagrams are tran ...
*
Lamit Company Lamit Company is an independent satellite operator company in Europe, operating worldwide. The company provides satellite internet and telephony to primary schools and high schools, universities, government institutions etc. Areas of the world ...
* NetHope#NetReliefKit *
SES Broadband SES Broadband (previously ASTRA2Connect) is a two-way satellite broadband Internet service available across Europe, which launched in March 2007, and uses the Astra series of geostationary satellites. SES Broadband is owned and operated by SE ...
(satellite Internet access in Europe) * StarBand *
Teledesic Teledesic was a company founded in the 1990s to build a commercial broadband satellite internet constellation. Using low-Earth-orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/s and downlinks of up to 720 ...
* Tooway * TS 2 *
Very small aperture terminal A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 16 ...
* Viasat Inc. (Excede Internet) *
Wireless Internet Service Provider A wireless Internet service provider (WISP) is an Internet service provider with a network based on wireless networking. Technology may include commonplace Wi-Fi wireless mesh networking, or proprietary equipment designed to operate over open ...


References


External links


ViaSat/TIA Satellite Equipment Systems Standardization Efforts
{{DEFAULTSORT:Satellite Internet Access Broadband