Satellite Internet Access is the Internet access provided through satellite communications. Modern-class satellite consumer Internet services are usually reserved for individual users via geostationary satellites that can offer relatively high data rates, with newer satellites using K a bands to achieve upstream data rates up to 50 Mbps.
Video Satellite Internet access
Sejarah Internet satelit
After the launch of the first satellite, Sputnik 1, by the Soviet Union in October 1957, the US successfully launched the Explorer 1 satellite in 1958. The first commercial communications satellite was Telstar 1, built by Bell Labs and launched in July 1962.
The idea of ​​geosynchronous satellites - which can orbit the Earth above the equator and keep it fixed by following the Earth's rotation - was first proposed by Herman Poto? Nik in 1928 and popularized by science fiction writer Arthur C. Clarke in a paper at Wireless World in 1945. The first satellite to reach geostationary orbit was Syncom3, built by Hughes Aircraft for NASA and launched on 19 August 1963. Continuing next generation communication satellites featuring greater capacity and better performance characteristics adopted for use in television shipments, military applications and telecommunications purposes. After the invention of the Internet and the World Wide Web, geostationary satellites have attracted interest as a potential means of providing Internet access.
A significant enabler of satellite-delivered Internet has become the opening of the K a band for satellites. In December 1993, Hughes Aircraft Co. appealed to the Federal Communications Commission to obtain a license to launch the first satellite a -band, Spaceway. In 1995, the FCC issued a call for more satellite apps K a , drew apps from 15 companies. Among them are EchoStar, Lockheed Martin, GE-Americom, Motorola and KaStar Satellite, which later became WildBlue.
Among the leading candidates in the early satellite Internet sector were Teledesic, an ambitious project and ultimately failed to be funded in part by Microsoft which ultimately cost more than $ 9 billion. The Teledesic idea is to create a constellation of satellite broadband from hundreds of low-orbiting satellites in the K a -band frequency, providing cheap Internet access with download speeds of up to 720 Mbit/s. The project was abandoned in 2003. Teledesic failure, coupled with bankruptcy filing from satellite communications provider Iridium Communications Inc. and Globalstar, reducing market enthusiasm for the development of satellite Internet. It was not until September 2003 when the first consumer ready-to-use satellite was launched by Eutelsat.
In 2004, with the launch of Anik F2, the first high throughput satellite, the next generation satellite class provides increased capacity and bandwidth into operational. Recently, high throughput satellites such as ViaSat satellite ViaSat in 2011 and Jupiter HughesNet in 2012 have achieved further improvements, increasing downstream data rates from 1-3 Mbit/s to 12-15Mbit/s and beyond. This satellite-related internet access service is targeted mostly for rural residents as an alternative to Internet services through dial-up, ADSL or FSSes classics.
Since 2014, more and more companies have announced working on Internet access using satellite constellations in low Earth orbit. SpaceX, OneWeb and Boeing all plan to launch over 1000 satellites each. OneWeb alone raised $ 1.7 billion in February 2017 for the project and SpaceX estimates more than $ 30 billion in revenue by 2025 from its satellite constellation. Many constellations are planned to use laser communications for inter-satellite links to effectively create a space-based Internet backbone.
By 2017, airlines like Delta and America have introduced satellite internet as a means to combat limited bandwidth in aircraft and offer internet speeds that passengers can use.
Maps Satellite Internet access
Enterprise and market
Companies that provide home internet services include ViaSat, through the Exede brand, and EchoStar, through its HughesNet subsidiary.
Function
Internet satellites generally rely on three main components: satellites, usually in geostationary orbit (sometimes referred to as geosynchronous Earth orbit, or GEO), a number of earth stations known as gateways that forward Internet data to and from satellites via microwave (microwave) , and a small antenna at the customer's location, often a VSAT antenna antenna (very small antenna antenna) with a transceiver. Other components of the satellite Internet system include a modem at the end of a user connecting a user's network with a transceiver, and a centralized network operations center (NOC) to monitor the entire system. Working in concert with a broadband gateway, Satellite operates a Star network topology where all network communications pass through a network hub processor, which is at the center of the star. With this configuration, the number of remote VSATs that can be connected to a hub is virtually unlimited.
Satellite
Marketed as a new broadband satellite network center is a new generation of high-powered GEO satellites positioned 35,786 kilometers (22,236 mi) above the equator, operating in K a -band (18.3-30 GHz). ) mode. The new satellites are designed and optimized for broadband applications, using many narrow point beams, targeting areas much smaller than the wide beams used by previous communications satellites. This spot beam technology allows satellites to reuse the specified bandwidth multiple times which enables them to achieve a much higher overall capacity than conventional broad beam satellites. Spot beams can also improve performance and consequential capacity by focusing more power and increasing the receiver's sensitivity to a defined concentration area. The spot beam is designated as one of two types: the beam where the customer, which sends to and from the customer-side terminal, and the gateway beam, sends to/from the service provider's carrier station. Note that moving a tight footprint from spotbeam can degrade performance significantly. Also, spotbeams can make it impossible to use other significant new technologies including modulation of 'Carrier in Carrier'.
In conjunction with satellite spot-beam technology, bent-pipe architecture has traditionally been used in networks where satellites serve as a bridge in space, connecting two communication points on the ground. The term "bending-pipe" is used to describe the shape of data paths between sending and receiving antennas, with satellites positioned at the turning point. Simply put, the role of the satellite in this network setting is to pass signals from the end user terminal to the ISP gateway, and back again without processing the signal on the satellite. The satellite receives, amplifies, and directs the introduction to a certain radio frequency through a signal path called a transponder.
Several proposed satellite constellations in LEO such as StarX SpaceX, Telesat and LeoSat constellations will use laser communications equipment for high-speed optical intercellular connections. Interconnected satellites make it possible to direct user data directly from satellite to satellite and effectively create a space-based optical mesh network that will enable seamless network management and service continuity.
The satellite has its own antenna device to receive communications signals from the Earth and send signals to their target locations. These antennas and transponders are part of the "payload" of satellites, designed to receive and transmit signals to and from different places on Earth. What enables this transmission and reception in a payload transponder is a repeater subsystem (RF equipment (radio frequency)) used to alter the frequency, filter, separate, amplify and signal groups before directing them to their destination address on Earth. High-gain satellite receiver antennas transmit data transmitted to transponders that filter, translate and amplify them, then direct them to the transmitting antenna on the board. The signal is then directed to a particular ground location through a channel known as the carrier. In addition to the payload, another major component of the communication satellite is called the bus, which consists of all the equipment necessary to move the satellite into position, power supply, regulate the temperature of the equipment, provide health information and tracking, and perform many other operational tasks.
Gateways
Along with dramatic advances in satellite technology over the last decade, ground equipment has also evolved, benefiting from higher levels of integration and improved processing power, expanded capacity and performance limits. Gateway - or Gateway Earth Station (full name) - also referred to as earth station, teleport or hub. This term is sometimes used to describe only the antenna portion of an antenna, or it can refer to a complete system with all the associated components. In a nutshell, the gateway receives the radio wave signal from the satellites on the last leg of the payback or the upstream payload, bringing the request that comes from the end user's site. The satellite modem at the gateway location demodulates the incoming signal from the outside antenna into the IP packet and sends packets to the local network. The server/gateway access controls the traffic that is transported to/from the Internet. After the initial request has been processed by the gateway server, sent to and returned from the Internet, the requested information is sent back as a forward or downward payload to the end user via satellite, which directs the signal to the customer terminal. Each Gateway provides connection to the Internet backbone for the beam gateway served. The gateway system comprising ground satellite systems provides all network services for satellites and appropriate terrestrial connectivity. Each gateway provides a multiservice access network for a customer terminal connection to the Internet. In the continent of the United States, since in the north of the equator, all dish antennas and customer dishes must have an unobstructed view of the southern sky. Due to the geostationary orbit of satellites, the gate antenna may remain fixed in a fixed position.
Antenna dish and modem
For customer-provided equipment (eg PCs and routers) to access broadband satellite networks, customers must have additional physical components installed:
Outdoor unit (ODU)
At the outer end of the outer unit is usually a small antenna dish antenna dish (2-3 feet in diameter). The VSAT antenna must also have an unobstructed view of the sky to allow precise line-of-sight (L-O-S) to the satellite. There are three physical characteristic settings that are used to ensure that the antenna is correctly configured in satellites, namely: azimuth, elevation, polarization, and tilt. This combination of arrangements provides L-O-S outdoor units to selected satellites and enables data transmission. This parameter is generally specified when the equipment is installed, together with file assignment (K a -band only); these steps should be taken before actual service activation. Sending and receiving components are usually installed at the focal point of the antenna receiving/transmitting data from/to the satellite. The main parts are:
- Feed - This assembly is part of a VSAT receiving and sending chain, consisting of several components with different functions, including a feed horn on the front of the unit, which resembles a funnel and has a microwave satellite signal focus on the reflector surface plate. The feed horns both receive the reflected signal from the disk surface and send the outgoing signal back to the satellite.
- Block upconverter (BUC) - This unit is behind the feed horn and may be part of the same unit, but larger (higher) BUC can be a separate part attached to the antenna base. The task is to change the signal from the modem to a higher frequency and amplify it before it is reflected off the disk and into the satellite.
- Block low-noise converter (LNB) - This is the terminal receiver element. The LNB task is to amplify received satellite radio signals that bounce off the disk and filter out noise, which is a signal that does not carry valid information. The LNB forwards the amplified signal and is filtered to the satellite modem at the user's location.
Indoor unit (IDU)
Satellite modems serve as interfaces between outdoor units and customer supplied equipment (eg PCs, routers) and satellite transmission and reception controls. From the sending device (computer, router, etc.) It accepts bitstream input and converts or modifies it into radio waves, reversing the sequence for incoming transmissions, called demodulations. It provides two types of connectivity:
- Coaxial cable (COAX) connectivity to a satellite antenna. Cables carrying electromagnetic satellite signals between modems and antennas are generally limited to no more than 150 meters in length.
- Ethernet connectivity to a computer, bringing customer data packets to and from an Internet content server.
Consumer-grade satellite modems typically use DOCSIS (Data Over Cable Service Interface Specification) or WiMAX (World Interoperability for Microwave Access) telecommunications standards to communicate with a defined gateway.
Challenges and limitations
signal latency
The latency (or 'ping time' as it is called) is a delay between requesting data and response reception, or in the case of one-way communication, between the actual time of the signal broadcast and the time it is received at the destination.
The radio signal takes about 120 milliseconds to reach the geostationary satellite and then 120 milliseconds to reach the earth station, so almost 1/4 of a second. Usually, during perfect conditions, the physics involved in satellite communications counts about 550 milliseconds of latent journey time.
The longer the latency is the main difference between standard terrestrial-based networks and geostationary-based satellite networks. The round trip latency of a geostationary satellite communications network can be more than 12 times that of terrestrial-based networks.
Geostationary orbit
A geostationary orbit (or geostationary Earth orbit/GEO) is a geosynchronous orbit directly above the equator of the Earth (0 Â ° latitude), with the same period as the Earth's rotation period and the zero-orbital eccentricity (ie "circular orbit"). An object in a geostationary orbit does not seem to move, in a fixed position in the sky, to a ground observer. Satellite communications and weather satellites are often given geostationary orbits, so satellite antennas that communicate with them do not have to move to trace them, but can be directed permanently to the position in the sky where they live. Since geostationary or geostationary orbital latitudes and circles are constant 0 °, the satellites in GEO differ in locations by merely longitude.
Compared to ground-based communications, all geostationary satellite communications experience higher latency because signals must travel 35,786 km (22,236 mi) to satellites in geostationary orbit and back to Earth again. Even at the speed of light (about 300,000 km/second or 186,000 miles per second), this delay can be significant. If all other delay signaling can be eliminated, it still needs radio signals around 250 milliseconds (ms), or about a quarter of a second, to travel to the satellite and back to the ground. The absolute minimum total delay is variable, since the satellites live in one place in the sky, while the land-based user can be directly below with an alternating latency of 239.6 ms, or far to the side of the planet near the horizon with an alternating latency of 279.0 ms.
For Internet packages, the delay is doubled before a reply is received. That is the theoretical minimum. Factoring in other normal delays from network sources provides a typical one-way connection latency of 500-700 ms from user to ISP, or about 1,000-1,400 ms latency for total round-trip (RTT) time back to the user. This is more than most dial-up users who experience a total latency of 150-200 ms, and is much higher than the 15-40 ms latency experienced by other high-speed Internet service users, such as cable or VDSL.
For geostationary satellites, there is no way to remove latency, but the problem can be somewhat diminished in Internet communications with the TCP acceleration feature that shortens the round-trip time (RTT) per packet by spoofing the feedback loop between the sender and receiver. Certain acceleration features are often present in the latest technological developments that are embedded in satellite Internet equipment.
Latency also impacts on the initiation of secure Internet connections such as SSL which requires exchanging a lot of data between web servers and web clients. Although these pieces of data are small, some of the travel rounds involved in handshakes result in long delays compared to other forms of Internet connectivity, as documented by Stephen T. Cobb in the 2011 report published by Rural Mobile and Broadband Alliances. This disruption extends into and edits data using some Software as a Service or SaaS application as well as other forms of online work.
Direct interactive access functionality to remote computers - such as virtual private networks should be thoroughly tested. Many TCP protocols are not designed to work in high latency environments.
Medium and Low Earth Orbit
Earth Earth Orbit (MEO) and low orbit satellite constellation (LEO) do not have very large delays because the satellites are closer to the ground. As an example:
- The current LEO constellation from Globalstar and Iridium satellites have a delay of less than 40 md of alternating trips, but the output is less than broadband at 64 kbit/dt per channel. The Globalstar constellation orbits 1.420 km above Earth orbit and Iridium at an altitude of 670 km.
- The O3b Networks MEO constellation orbits at 8.062 km, with RTT latency of around 125 ms. The proposed new network is also designed for higher throughput with links that exceed 1 Gbit/s (Gigabits per second).
Unlike geostationary satellites, low or middle Earth orbit satellites do not stay in a fixed position in the sky. As a result, ground-based antennas can not be easily locked in communications with one particular satellite. Like GPS, for satellite receivers can only be seen for parts of their orbits, therefore some satellites are required to make permanent internet connections, with low Earth orbit requiring more satellites than a moderate Earth orbit. The network must transfer data transfer between satellites to maintain connections to customers.
Communications with MEO or LEO satellites moving in the sky can be done in three ways:
- A more diffuse or omnidirectional ground antenna capable of communicating with one or more satellites visible in the sky at the same time, but at a significantly higher transmit power than a fixed geostationary antenna antenna (due to the advantage which is lower), and with a worse signal to noise ratio for receiving signals.
- Motorized antenna antennas with narrow and narrow beam antennas that track individual satellites
- Staged array antennas that can direct files electronically, along with software that can predict the path of every satellite in a constellation.
ultralight aircraft as satellite
A proposed alternative to satellite relays is a special-purpose ultralight solar-powered aircraft, which will fly along circular paths over fixed ground locations, operating under autonomous computer control at an altitude of about 20,000 meters.
One example of this project is the Vulture Project The United States Advanced Defense Research Project, an ultralight aircraft that aims to maintain stations over fixed areas for a period of up to five years, able to provide continuous monitoring of land assets and provide a latency communication network that very low. The project was canceled in 2012 before it became operational.
Onboard batteries will be worn during the day by solar panels covering the wings, and will provide power to the plane during the night. The ground-based satellite dish will send signals to and from the plane, thereby reducing the latency of the signal back and forth by only 0.25 milliseconds. The planes could potentially run for long periods without refueling. Several schemes involving different 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 the end user or the earth station and the satellites used. Interference with this signal is known as fading rain . The effect is less clear at low frequencies 'L' and 'C' bands, but can become very severe at higher frequencies 'Ku' and 'Ka' bands. For satellite Internet services in the tropics with heavy rain, the use of C bands (4/6Ã, GHz) with satellite circular polarization is very popular. The satellite communications on the ribbon K a (19/29 GHz) can use special techniques such as large rain margin < adaptive uplink power control and reducing bit rate during precipitation.
Rain margin is an extra communications requirement required to account for signal degradation due to moisture and precipitation, and is critical for all systems operating at frequencies above 10 GHz.
The amount of time that a lost service can be reduced by increasing the size of the satellite communications antenna so that it can collect more satellite signals in the downlink and also to provide a stronger signal on the uplink. In other words, increasing the antenna gain through the use of larger parabolic reflectors is one way to improve overall channel gain and, consequently, the signal-to-noise ratio (S/N), which allows for greater signal loss due to rain faded without the S/N ratio falling below the minimum threshold for successful communication.
Modern consumer-grade dish antennas tend to be small enough, which reduces the rain margin or increases the power and downlink costs of the satellites required. However, it is often more economical to build more expensive and smaller satellites, consumer antennas that are cheaper than increasing the size of consumer antennas to reduce satellite costs.
Large commercial dishes with a diameter of 3.7 m to 13 m can be used to achieve increased rain margins and also to reduce cost per bit by allowing more efficient modulation codes. Alternately, larger aperture antennas may require less power than satellites to achieve acceptable performance. Satellites typically use photovoltaic solar power, so there is no cost for the energy itself, but more powerful satellites will require bigger, stronger solar and electronic panels, often including larger transmitting antennas. Larger satellite components not only increase material costs but also increase satellite weights, and in general, the cost of launching satellites into orbit is directly proportional to its weight. (Also, since satellite launch vehicles [ie rockets] have specific charge-size limits, making parts of larger satellites may require more complicated folding mechanisms for satellite parts such as solar panels and high-income antennas, or upgrading to more expensive launch vehicles that can handle larger payloads.)
Modulated operators can be dynamically changed in response to rain problems or other linkages using a process called encoding and adaptive modulation, or "ACM". ACM allows bit rates to increase substantially during normal sunny sky conditions, increasing the number of bits per transmitted Hz, and thus reducing overall cost per bit. The adaptive coding requires some kind of return channel or feedback through any available means, satellite or terrestrial.
View line
The object is in your line of sight if you can draw a straight line between yourself and the object without any disturbance, like a mountain or a bend in the road. An object outside the horizon is below the line of sight and, therefore, can be difficult to communicate.
Usually a perfectly clear line of sight between the dish and the satellite is required for the system to work optimally. In addition to signals that are susceptible to absorption and scattering by water vapor, the signal is also affected by the presence of trees and other vegetation in the signal path. When radio frequency decreases, to below 900 MHz, penetration through vegetation increases, but most satellite communications operating above 2 GHz make them sensitive to even small obstructions such as tree foliage. Installing dishes in the winter should consider the growth of plant leaves that will appear in the spring and summer.
Fresnel Zone
Even if there is a direct line of sight between transmitting and receiving antennas, the reflection of objects near the signal path can decrease the apparent signal power through phase cancellation. Whether and how many signals are lost from the reflection is determined by the location of the object in the Fresnel zone of the antenna.
Two-way satellite communication only
Two-way, home-class satellite Internet service involves sending and receiving data from a very small remote-aperture (VSAT) terminal via satellite to a teleport hub port (teleport), which then relays data over the terrestrial Internet. Satellite dishes at each location must be appropriately pointed to avoid interference with other satellites. At each VSAT site, the uplink, bit rate and power frequencies must be set accurately, under the control of the service provider's center.
There are several types of satellite two-way Internet services, including dual access time sharing (TDMA) and single channel per carrier (SCPC). A two-way system can be a simple VSAT terminal with a 60-100 cm dish and a power output of just a few watts intended for consumers and small businesses or larger systems that provide more bandwidth. Such systems are often marketed as "satellite broadband" and can cost two to three times more per month such as land-based systems such as ADSL. Modems required for this service are often patented, but some are compatible with several different providers. They are also expensive, costing in the range of USD $ 600 to $ 2000.
Two-way "iLNB" used on SES Broadband terminal disks has a single transmitter and polarity receiving LNB, both operating in the band K u . Prices for SES Broadband modems range from EUR299 to EUR350. This type of system is generally unsuitable for use on moving vehicles, although some dishes may be fitted to automatic pan and tilt mechanisms to align the dish continuously - but this is more expensive. The technology for SES Broadband was delivered by a Belgian company named Newtec.
Bandwidth
Satellite Internet subscribers subscribers range from individual home users to one PC to large business sites that are away with several hundred PCs.
Home users tend to use shared satellite capacity to reduce costs, while still allowing high peak bit rates when congestion does not exist. There is usually a limited time-limited bandwidth limit so that each user gets his fair share, according to their payment. When a user exceeds their allowance, companies can slow down their access, prioritize their traffic or charge for excess bandwidth used. For satellite Internet consumers, benefits usually can range from 200 MB per day up to 25 GB per month. Shared download operators can have 1 to 40 Mbit/s bit rate and are distributed up to 100 to 4,000 end users.
The uplink direction for shared users is usually a dual access time division (TDMA), which involves occasional short packet delivery among other users (similar to how cell phones share cell towers).
Each remote location may also be equipped with a telephone modem; the connection for this is the same as a conventional dial-up ISP. Two way satellite systems can sometimes use a modem channel in both directions for data where latency is more important than bandwidth, storing satellite channels to download data where bandwidth is more important than latency, such as for file transfers.
In 2006, the EC sponsored a UNIC project aimed at developing an end-to-end scientific testing venue for the distribution of new broadband broadcast TV-centric services delivered via low-cost two-way satellite to real end-users at home. UNIC Architecture uses DVB-S2 standard for downlink and DVB-RCS standards for uplink.
The normal VSAT plate (diameter 1.2-2.4 m) is widely used for VoIP phone service. Voice calls are sent via packets via satellite and Internet. Using encoding and compression techniques, the required bit rate per call is only 10.8 kbit/s.
Portable satellite Internet
Portable satellite modem
It usually comes in the form of a flat, self-contained rectangular box that needs to be directed towards a common satellite - unlike the VSAT, the juxtaposition does not need to be very precise and the modem has built in signal strength meters to aid the user. align the device correctly. Modems have commonly used connectors such as Ethernet or Universal Serial Bus (USB). Some also have integrated Bluetooth transceivers and doubles as satellite phones. Modems also tend to have their own batteries so they can connect to the laptop without draining the battery. The most common system is BGAN INMARSAT - this terminal is about the size of a suitcase and has close symmetric connection speeds of 350-500 kbit/s. Smaller modems exist such as those offered by Thuraya but are only connected at 444 kbit/dt in limited area coverage. INMARSAT now offers IsatHub, a booklet-sized satellite modem that works with mobile phone users and other devices. The cost has been reduced to $ 3 per MB and the device itself sells for about $ 1300.
Using such a modem is very expensive - bandwidth costs between $ 5 and $ 7 per megabyte. The modem itself is also expensive, usually costing between $ 1,000 and $ 5,000.
Internet via satellite phone
Over the years satellite phones have been able to connect to the Internet. Bandwidth varies from about 2400 bits/s to Iridium network satellites and ACeS-based phones up to 15'bit/s upstream and 60db/s for Thuraya handsets. Globalstar also provides Internet access at 9600 bit/s - such as Iridium and ACeS dial-up connections are required and billed per minute, but both Globalstar and Iridium plan to launch new satellites that offer data services that are always active at a higher level. With Thuraya phone, a 9,600 bit/s dial-up connection is also possible, 60 kbit/s service is always on and users are billed for data transferred (about $ 5 per megabyte). The phone can be connected to a laptop or other computer using a USB or RS-232 interface. Because of the low bandwidth involved it is very slow to surf the web with such connections, but is useful for sending emails, Secure Shell data and using other low-bandwidth protocols. Since satellite phones tend to have omnidirectional antennas, no alignment is needed as long as there is a line of sight between the phone and the satellite.
One-way reception, with terrestrial transmission
A one-way terrestrial satellite satellite Internet system is used with conventional dial-up Internet access, with outbound data (upstream) via telephone modem, but downstream data transmitted via satellite at a higher rate. In the US, FCC licenses are required only for uplink stations; no license required for user.
Another type of 1-way satellite Internet system uses General Packet Radio Service (GPRS) for the back channel. By using standard GPRS or Enhanced Data Rates for GSM Evolution (EDGE), the cost is reduced for a higher effective rate if the upload volume is very low, and also because the service is not charged per time, but is charged by the uploaded volume. GPRS as a return increases mobility when the service is provided by satellites transmitting in the 50-53 dBW field. Using a 33 cm wide satellite dish, a normal GSM notebook and GPRS phone, users can get satellite mobile broadband.
System components
The transmitter station has two components, consisting of a high-speed Internet connection to serve many customers at once, and a satellite uplink to broadcast the requested data to the customer. The ISP router connects to a proxy server that can implement the service quality bandwidth limit (QoS) and warranty for each customer's traffic.
Often, non-standard IP stacks are used to address latency issues and satellite connection asymmetry. As with one-way receiving systems, data sent via satellite links is generally also encrypted, because otherwise it will be accessible to anyone with a satellite receiver.
Many IP-over-satellite implementations use proxy servers in pairs at both endpoints so that certain communications between client and server need not receive latency attached to satellite connections. For the same reason, there is a dedicated virtual private network (VPN) implementation designed for use over satellite links because standard VPN software can not handle long packet travel times.
The upload speed is limited by the user's dial-up modem, while the download speed can be very fast compared to dial-up, using the modem only as a control channel for packet recognition.
Latency is still high, though lower than a full two-way geostationary satellite Internet, as it is only half of the data path through satellite, the other half through terrestrial channels.
One-way broadcast, receive only
One way satellite Internet system is used for Internet Protocol (IP) based data distribution, audio and video distribution. In the US, Federal Communications Commission (FCC) licenses are only required for uplink stations and no licenses are required for users. Note that most Internet protocols will not work correctly through one-way access, because they require a return channel. However, Internet content such as web pages can still be distributed through a one-way system by "pushing" them out to local storage on end user sites, although full interactivity is not possible. It's like TV or radio content that offers a bit of user interface.
Broadcast mechanisms may include compression and error correction to help ensure one-way broadcasts are received correctly. The data may also be re-broadcast periodically, so previously unsuccessful recipients will have an additional opportunity to try downloading again.
Data can also be encrypted, so that whilst anyone can receive data, only certain purposes can actually decode and use broadcast data. Legitimate users only need to have either a short decryption key or an automated code device tool that uses its highly independent independent time mechanism to decrypt data.
System hardware components
Similar to one-way terrestrial returns, satellite Internet access may include an interface to a public switched telephone network for plaid applications. Internet connection is not required, but many applications include File Transfer Protocol (FTP) server to queue for data to broadcast.
System software components
Most one-way broadcast applications require special programming on remote sites. The software on the remote site must filter, store, present the selection interface and display the data. The software at the transmitting station should provide access control, queuing priority, delivery, and data encapsulation.
Services
Emerging commercial services in this area include:
- Outernet - satellite constellation technology
Increased efficiency
The FCC 2013 report mentions a big jump in satellite performance
In its report released in February 2013, the Federal Communications Commission recorded significant advances in satellite Internet performance. Broadband America Measures Report FCC also ranks the major ISPs with how close they are to the advertised speed. In this category, satellite Internet ranks top, with 90% of subscribers seeing speeds at 140% or better than advertised.
Reduce satellite latency
Much of the slowdown associated with satellite Internet is that for every request, many round trips must be completed before useful data can be received by the applicant. Special IP stacks and proxies can also reduce latency through reducing the number of round trips, or simplifying and reducing the protocol header length. Optimization technologies include TCP acceleration, HTTP pre-fetching and DNS cache among many others. See Standard Space Communication Spek (SCPS), developed by NASA and widely adopted by commercial and military equipment and software providers in the market space.
Satellites launched
The WINDS 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 provides a maximum speed of 155 Mbit/s and 6 Mbit/s to residence with 45 ° C aperture antenna, and 1.2 Gbit/s connection for business 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 was launched in November 2010, targeting Europe.
On December 26th 2010, KA-SAT Eutelsat was launched. It covers the European continent with 80 signal point - focused signals covering several hundred kilometers of territory in Europe and the Mediterranean. Spot beams allow frequencies to be used effectively in different areas without interruption. The result is an increase in capacity. Each beam has an overall capacity of 900 Mbit/s and all satellites will have a capacity of 70 Gbit/s.
ViaSat-1, the highest capacity communications satellite in the world, launched on October 19, 2011 from Baikonur, Kazakhstan, offers 140 Gbit/s total capacity, through Exede Internet service.
Passengers on JetBlue Airways can use this service since 2015.
The EchoStar XVII satellite was launched July 5, 2012 by Arianespace and placed in a permanent geosynchronous orbital slot of 107.1 Â ° West Longitude, HughesNet's service. This K a satellite has a throughput capacity of more than 100 Gbit/s.
Since 2013, the O3b satellite constellation claims a round-to-end latency of 238 ms for data services.
See also
References
External links
- ViaSat/TIA Satellite Equipment System Standardization Effort
Source of the article : Wikipedia
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