From Arpanet to Satellite Internet - An Online Timeline
By Harvey Markus
Today, the Internet is everywhere. Literally. With the help of Wi-Fi and satellite Internet, there isn't a remote corner of the world where you can't connect. Many of us take Internet access for granted, never leaving home without our iPhone or Blackberry. Indeed, dial-up AOL seems a thing of the distant past, not to mention what preceded it. But, though it may be hard to remember a time without the web, things were not always this way. Here's a timeline marking some important milestones in the history of the Internet.
1969: Arpanet, the network that was to become the basis for the Internet, came to fruition on October 29, connecting for university computers and Stanford and UCLA. Unix was developed the same year by a group of AT&T employees and later influenced the design of the Linus and FreeBSD operating systems popularly used in today's servers.
1970: An Arpanet network was established between Harvard, MIT, and BBN.
1971: Email was created by Ray Tomlinson, who also initiated the use of the @ symbol. Project Gutenberg also began in 1971, putting computer storage capacity to use in the birth of eBooks.
1973: Arpanet made the first trans-Atlantic connection with University College London. The same year also saw the popularity of email rise to 75% of all Arpanet network activity.
1974: It was proposed that all Arpa-like networks be linked together in one "inter-network." This idea gave birth to what eventually became TCP/IP.
1975: John Vittal developed the first modern email program, which included "reply" and "forward" functions.
1977: The PC modem was developed by Dennis Hayes and Dale Heatherington and used by computer hobbyists.
1978: The first unsolicited commercial email message, or spam, was sent.
1979: Grandfather to World of Warcraft and Second Life, text-based MUD (short for MultiUser Dungeon), became the first multi-player game, mixing role-playing, interactive, fictional, and online chat components.
1982: The first emoticon: - ) was brought into use after jokes.
1983: Arpanet computers switched over to TCP/IP.
1984: The domain name system (DNS) was created to make online addresses more user-friendly, replacing a series of numbers with easy-to-remember words.
1987: The number of hosts on the Internet grew to 30,000.
1988: Internet Relay Chat (IRC) was first used, laying the foundation for real-time chat and the instant-messaging programs used today.
1988: "The Morris Worm," one of the first major Internet worms was released, resulting in significant interruptions for many users.
1989: AOL was launched.
1989: The concept behind the World Wide Web was proposed.
1990: Arpanet was retired and the first commercial dial-up ISP, The World, was introduced, and the World Wide Web code was written, including standards for HTML, HTTP, and URLs.
1991: The first web page created as a World Wide Web tutorial. The same year brought into existence the first content-based search protocol, called Gopher, as well as MP3 standardization and the first webcam.
1993: Mosaic became the first web browser that was easy for the general public to use. Governments also began to go online, introducing.org and.gov domain names.
1994: Netscape Navigator became Mosaic's first big competitor.
1995: This year is credited for the commercialization of the Internet, the launch of Geocities and Java, and Internet use by the Vatican.
1996: Hotmail, the first webmail service, was launched. Also, the first consumer Satellite Internet service became available.
1997: The term "weblog" was coined.
1998: The Bill Clinton/Monica Lewinsky scandal became the first news story to be broken online rather than through traditional media. Google was born in the same year, and Internet-based file-sharing became popular with Napster.
2000: The dotcom bubble burst, causing devastating losses for many investors.
2001: Wikipedia was launched.
2003: VoIP (Voice Over IP) calling was released to the public in the form of Skype, MySpace became the most popular social network, and the CAN-SPAM Act helped control the problem of unsolicited pornographic emails.
2004: "Web 2.0" and "social media" became mainstream concepts, in the same year that Facebook (later to overtake MySpace in popularity) was first opened to college students.
2005: YouTube made free online video sharing and hosting available to the masses.
2006: Twitter was launched.
2007: TV shows became legally available online with the launch of Hulu in the same year that the revolutionary iPhone was introduced, drawing attention to mobile web applications and design.
2008: The United States presidential campaigns took advantage of the Internet through online campaign videos and fundraising through Facebook.
As our world becomes increasingly dependent on the Internet, new innovations are constantly being introduced to make our lives easier and faster. Just as dial-up was once considered groundbreaking and speedy, in the rapidly changing world of technology, it's hard to say exactly what the future has in store for what are currently considered high-speed connections, like cable, DSL, and satellite broadband. But when you look at how far we've come since the humble beginnings of Arpanet, the progress is remarkable.
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Article Source: [http://EzineArticles.com/?From-Arpanet-to-Satellite-Internet---An-Online-Timeline&id=3764947] From Arpanet to Satellite Internet - An Online Timeline
Saturday, January 8, 2011
Satellite Internet Reviews
Satellite Internet Reviews - The Wonderful and the Not So Wonderful World of Internet Via Satellite
By Carl Langlois
There is no question that for the many people who live in areas where there is no DSL or cable internet, getting high speed internet is a problem. Many have turned to internet via satellite to get away from dial-up. If you are considering the same thing, it may be a good idea to check out a few satellite internet reviews before you decide.
A satellite internet service can be wonderful, but it can also be not so wonderful.
The wonderful comes with being able to do the things that those who have true high speed internet can do. Things like finally being able to download a few pictures from your email or check out a shopping site without waiting for minutes for an image to load. If you have been living with dial up you know how great this is.
With a high speed satellite internet service you can surf the internet and even run an online business. You will be able to upload files to your website quickly and set up payment portals, etc. It allows you to do office work from home while connecting with colleagues in the office in the city. You can send and receive big files including graphics as well as doing online chat. Although download speeds are not as fast as with DSL or cable, you can still watch videos and download podcasts. You can quickly post in forums and keep up with friends on social Web2.0 sites, like Facebook or Twitter.
But realistic satellite internet reviews must include the not so wonderful as well. The two biggest drawbacks to internet using a satellite are the weather factors and the cost. Internet using a satellite can be affected by the weather. If you use satellite TV you know that the signal can be interrupted by severe weather. Well, satellite internet is affected in a similar way. When there is a heavy rainstorm your service may slow down or even be interrupted for a period of time. There is really no way around this. The satellite is in the sky and weather affects it. Snow can be worse. If the dish gets covered with snow the signal stops transmitting. You'll have to manually brush off the dish or wait for the snow to melt before service will resume.
The other drawback to satellite internet is the cost. With regular high speed internet you can get a basic plan for a very reasonable amount and you can download an almost unlimited amount of data. Internet using satellite is much more expensive. And you are limited as to the number of megabytes you can use in a day. You can certainly buy a bigger package but the cost is much greater.
Be sure to check out a number of satellite internet reviews if you are sick of dial up, to see if it really is for you.
For more satellite internet reviews and to find out where to get the best satellite internet visit http://www.satelliteinternet-now.com/
Article Source: [http://EzineArticles.com/?Satellite-Internet-Reviews---The-Wonderful-and-the-Not-So-Wonderful-World-of-Internet-Via-Satellite&id=3755515] Satellite Internet Reviews - The Wonderful and the Not So Wonderful World of Internet Via Satellite
By Carl Langlois
There is no question that for the many people who live in areas where there is no DSL or cable internet, getting high speed internet is a problem. Many have turned to internet via satellite to get away from dial-up. If you are considering the same thing, it may be a good idea to check out a few satellite internet reviews before you decide.
A satellite internet service can be wonderful, but it can also be not so wonderful.
The wonderful comes with being able to do the things that those who have true high speed internet can do. Things like finally being able to download a few pictures from your email or check out a shopping site without waiting for minutes for an image to load. If you have been living with dial up you know how great this is.
With a high speed satellite internet service you can surf the internet and even run an online business. You will be able to upload files to your website quickly and set up payment portals, etc. It allows you to do office work from home while connecting with colleagues in the office in the city. You can send and receive big files including graphics as well as doing online chat. Although download speeds are not as fast as with DSL or cable, you can still watch videos and download podcasts. You can quickly post in forums and keep up with friends on social Web2.0 sites, like Facebook or Twitter.
But realistic satellite internet reviews must include the not so wonderful as well. The two biggest drawbacks to internet using a satellite are the weather factors and the cost. Internet using a satellite can be affected by the weather. If you use satellite TV you know that the signal can be interrupted by severe weather. Well, satellite internet is affected in a similar way. When there is a heavy rainstorm your service may slow down or even be interrupted for a period of time. There is really no way around this. The satellite is in the sky and weather affects it. Snow can be worse. If the dish gets covered with snow the signal stops transmitting. You'll have to manually brush off the dish or wait for the snow to melt before service will resume.
The other drawback to satellite internet is the cost. With regular high speed internet you can get a basic plan for a very reasonable amount and you can download an almost unlimited amount of data. Internet using satellite is much more expensive. And you are limited as to the number of megabytes you can use in a day. You can certainly buy a bigger package but the cost is much greater.
Be sure to check out a number of satellite internet reviews if you are sick of dial up, to see if it really is for you.
For more satellite internet reviews and to find out where to get the best satellite internet visit http://www.satelliteinternet-now.com/
Article Source: [http://EzineArticles.com/?Satellite-Internet-Reviews---The-Wonderful-and-the-Not-So-Wonderful-World-of-Internet-Via-Satellite&id=3755515] Satellite Internet Reviews - The Wonderful and the Not So Wonderful World of Internet Via Satellite
How Dish Internet Works
Satellite Internet access is Internet access provided through satellites. The service can be provided to users world-wide through Low Earth Orbit (LEO) satellites. Geostationary satellites can offer higher data speeds, but their signals can not reach some polar regions of the world. Different types of satellite systems have a wide range of different features and technical limitations, which can greatly affect their usefulness and performance in specific applications.
Signal latency
Satellite Internet access via VSAT in Ghana
Latency 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 received at its destination. Compared to ground-based communication, all geostationary satellite communications experience high latency due to the signal having to travel 35,786 km (22,236 mi) to a satellite in geostationary orbit and back to Earth again. Even at the speed of light (about 300,000 km/s or 186,000 miles per second), this delay can be significant. If all other signaling delays could be eliminated it still takes a radio signal about 250 milliseconds, or about a quarter of a second, to travel to the satellite and back to the ground. 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 milliseconds latency for the total Round Trip Time (RTT) back to the user. This is much more than most dial-up users experience at typically 150–200 ms total latency.
This inherent latency makes Satellite Internet service essentially unusable for applications requiring real-time user input, such as online games or remote surgery. This delay can also be irritating and debilitating with interactive applications, such as VoIP, videoconferencing, or other person to person communication. It will cause most general market applications (such as Skype) to behave unpredictably and fail, as these are not designed for the difficult compensation for the high latency connections. As research has repeatedly demonstrated that perceived delays in answering questions subconsciously suggests doubt to the listener and can generate mistrust even when both sides are aware of the lag[citation needed] , geostationary connections are best avoided for important voice calls. Other research[citation needed] into interactive systems has repeatedly demonstrated that latency lag is the most debilitating and irritating of all interactive system flaws and often gives an extremely negative impression of the system or its usefulness. Some researchers have gone so far as to recommend simply refusing connections to those with latency likely to result in poor interactive user experience.
The functionality of live interactive access to a distant computer can also be subject to the problems caused by high latency. However these problems are more than tolerable for basic email access and web browsing, and in most cases are barely noticeable. This is not true, however, for character-by-character command shell or virtual private networks (which typically involve several round trips using layered protocols) which are almost universally unusable through geostationary connections. Typical VPN connections made over satellite will be at least double (and often, with poor protocols and misguided security measures) quadruple or worse the underlying basic latency.. Unless the VPN is literally re-engineered to accommodate high-latency users, it will be useless for anything but email, download and a static web.
For geostationary satellites there is no way to eliminate latency, but the problem can be somewhat mitigated in Internet communications with TCP acceleration features that shorten the round trip time (RTT) per packet by splitting the feedback loop between the sender and the receiver. Such acceleration features are usually present in recent technology developments embedded in new satellite Internet services.
Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellites do not have such great delays. The current LEO constellations of Globalstar and Iridium 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 proposed O3b Networks MEO constellation scheduled for deployment in 2010 would orbit at 8,062 km, with RTT latency of approximately 125 ms. The proposed new network is also designed for much higher throughput with links well in excess of 1 Gbps (Gigabits per second).
A proposed alternative to geostationary relay satellites is a special-purpose solar-powered ultralight 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. Onboard batteries would be charged during daylight hours by solar panels covering the wings, and would provide power to the plane during night. Ground-based satellite 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 then run forever without refueling. Several such schemes involving various types of aircraft have been proposed in the past.
A foldable Bigpond Satellite Internet dish
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. 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 produce a more intense transmission on the uplink.
Modern consumer-grade dish antennas tend to be fairly small, which reduces the rain margin or increases the required satellite downlink power and cost.
Large commercial dishes of 3.7m to 13m diameter are used to achieve large rain margins and also to reduce the cost per bit by requiring far less power from the satellite.
Modern download DVB-S2 carriers, with RCS feedback, are intended to allow the modulation method to be dynamically altered, in response to rain problems at a receive site. This allows the bit rates to be increased substantially during normal clear sky conditions, thus reducing overall costs per bit.
Fresnel zone. d is the distance between the transmitter and the receiver, b is the radius of the Fresnel zone.
Typically a completely clear line of sight between the dish and the satellite is required for the system to work. 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.
The radio signal width between two ground satellite dish receivers is not perfectly straight and uniform, as if it were a beam of light. Instead as the signal propagates away from the transmitting dish, it widens towards the centerpoint between the two dishes and then narrows again as it approaches the receiving dish. This is known as the fresnel zone, and limits the usefulness of satellite dishes in locations where there is extremely limited open sky for signal reception. The signal path through space must be clear not only for direct line of sight, but must also be clear for the expanding fresnel zone, which may be several meters larger in diameter than the ground-based satellite dish.
The back panel of a satellite modem, with coaxial connections for both incoming and outgoing signals, and an Ethernet port for connection to the internal network.
Two-way satellite Internet service involves both sending and receiving data from the remote VSAT site via satellite to a hub 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. Some providers oblige the customer to pay for a member of the provider's staff to install the system and correctly align the dish—although the European ASTRA2Connect system encourages user-installation and provides detailed instructions for this. Many customers in the Middle East and Africa are also encouraged to do self installs. 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 (TDMA) and single channel per carrier (SCPC). Two-way systems can be simple VSAT 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. The modems 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 ASTRA2Connect.
The two-way "iLNB" used on the ASTRA2Connect terminal dish has a 500 mW transmitter and single-polarity receive LNB, both operating in the Ku band. Pricing for Astra2Connect 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 cumbersome and very expensive. The technology for ASTRA2Connect was delivered by a Belgian company called Newtec.
The Tooway satellite modem
Satellite internet customers range from individual home users with one PC to large remote business sites with several hundred PCs.
Home users tend to make use of 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 Mbytes allowances, 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 17,000 MB per month. A shared download carrier may have a bit rate of 1 to 40 Mbit/s and be shared by up to 100 to 4000 end users. Note that the average bit rate per end user PC is only about 10 - 20kbit/s.
The uplink direction for shared user customers is normally TDMA, which involves transmitting occasional short packet bursts in between other users (similar to how a cellphone shares a cell tower)
Business users tend to opt for dedicated bandwidth services where any congestion is under their local control.
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 transfers.
In 2006 the European Commission sponsored the UNIC project which aims at developing 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 standard for downlink and DVB-RCS standard for uplink.
Normal VSAT dishes (1.2 - 2.4m dia) 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.
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 or Universal serial bus. Some also have an integrated Bluetooth transceiver and double as a satellite phone. The modems also tend to have their own batteries so they can be connected to a laptop without draining its battery. The most common such system is INMARSAT's BGAN—these terminals are about the size of a briefcase and have near-symmetric connection speeds of around 350–500 kbit/s. Smaller modems exist like those offered by Thuraya but only connect at 144 kbit/s in a limited coverage area.
Using such a modem is extremely expensive—bandwidth costs between $5 and $7 per megabyte. The modems themselves are also expensive, usually costing between $1000 and $5000.
For many years now satellite phones have been able to connect to the internet. Bandwidth varies from about 2400 bit/s for Iridium network satellites and ACeS based phones to 15 kbit/s upstream and 60 kbit/s downstream for Thuraya handsets. Globalstar also provides internet access at 9600 bit/s—like Iridium and ACeS a dial-up connection is required and is billed per minute, however both Globalstar and Iridium are planning to launch new satellites offering always-on data services at higher speeds. With Thuraya phones the 9600 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 phones can be connected to a laptop or other computer using a USB or RS-232 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 data and using other low-bandwidth protocols. Since satellite phones tend to have omnidirectional antennas no alignment is required as long as there is a line of sight between the phone and the satellite.
One-way terrestrial return satellite Internet systems are used with traditional dial-up access to the Internet, with outbound data traveling through a telephone modem, but downloads sent via satellite at a speed near that of broadband Internet access. 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 involves the use of General Packet Radio Service (GPRS) for the back-channel.By utilizing a connection that is offered in standard GPRS or EDGE, the upload volume is very low and since this service is not per-time charged, but charged by volume uploaded, users are able to surf and download in broadband speeds. Another view of using GPRS as return would be the mobility when the service is provided by a satellite that transmits in the field of 50 to 53 dBW. Using a 33 cm wide satellite dish, a notebook and a normal GPRS equipped GSM phone, users can get mobile satellite broadband.
The transmitting station (also called "teleport", "head end", "uplink facility", or "hub") has two components:
* Internet connection: The ISP's routers connect to proxy servers which can enforce quality of service (QoS) bandwidth limits and guarantees for user traffic. These are then connected to a DVB encapsulator which is then connected to a DVB-S modulator. The radio frequency (RF) signal from the DVB-S modulator is connected to an up converter which is connected via feed line to the outdoor unit.
* Satellite uplink: The block upconverter (BUC) and optional low-noise block converter (LNB), which may use a waveguide to connect to the optional orthomode transducer (OMT) which is bolted to the feed horn which is connected by metal supports to the satellite dish and mount.
At the remote location (Earth station) the setup consists of:
* Outdoor unit
o Satellite dish with mount
o Feedhorn
o Universal LNB, for Ku-band.
o Feed line
* Indoor unit
o DVB-S Peripheral Component Interconnect (PCI) card internal to a computer
o or, DVB external modem where an 8P8C (RJ-45) Ethernet port or a Universal Serial Bus (USB) port connects the modem to the computer
Remote sites require a minimum of programming to provide authentication and set proxy server settings. Filtering is usually provided by the DVB card driver.
Often, non-standard IP stacks are used to address the latency and asymmetry problems of the satellite connection. 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 do not need to accept the latency inherent in a satellite connection. For similar reasons, there exist special Virtual private network (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, and latency is high, as it is for any satellite based Internet (minimum of 240 ms one-way, resulting in a minimum round-trip time of almost 500ms). Download speeds can be very fast compared to dial-up.
Remote sites use proxy server or(and) Virtual private network servers at the earth station (teleport), which is configured to route all outbound traffic to the QoS server, which makes sure no user exceeds their allotted bandwidth or monthly traffic limits. Traffic is then sent to the encapsulator, which puts the IP packets inside of DVB packets. The DVB packets are then sent to the DVB modem and then to the transmitter (BUC)
One-way multicast satellite Internet systems are used for Internet Protocol (IP) multicast-based data, audio and video distribution. In the U.S., a Federal Communications Commission (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.
Similar to one-way terrestrial return, satellite Internet access may include interfaces to the public switched telephone network for squawk box applications. An Internet connection is not required, but many applications include a File Transfer Protocol.
Most one-way multicast 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.
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. These types of technologies are generally referred to as TCP acceleration, HTTP pre-fetching and DNS caching.
While also effective for terrestrial communications, the use of ad-blocking software such as Adblock for Firefox is exceptionally beneficial for satellite Internet, as most Internet advertising websites use cache busting in order to render the browser and ISP's cache useless, by displaying advertisements (for the purpose of maximizing the number of ad views seen by the affiliate marketing company's server).
SkyTerra-1 was launched in mid-November and will provide service across North America while Hylas-1 was launched at the end of November and will target Europe. And at December 26, 2010, Eutelsat's Ka-Sat was successfully launched by an ILS Proton Breeze M vehicle at the Baïkonour Cosmodrome Kazakhstan. The last satellite is due in service in 2011 and is the third broadband Internet satellite to be launched in the last six weeks. It will cover the 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 will have an overall capacity of 900Mbps and the entire satellite will have a capacity of 70Gbps.
Hughes Network Systems
A wholly owned subsidiary, Hughes Network Systems is a provider of broadband satellite network products for businesses and consumers. Headquartered outside Washington, D.C., in Germantown, Maryland, USA, it maintains sales and support offices worldwide and employs approximately 1,500 people in engineering, operations, marketing, sales and support. It also operates manufacturing facilities in Gaithersburg, Maryland. It first opened its doors in 1971 as Hughes Electronics, which expanded in 1987 with the purchase of M/A-COM Telecommunications. In January 2003, the company was sold to SkyTerra Communications. Hughes pioneered the development of high-speed satellite Internet services, which it markets globally under the “Hughes Net brand. Hughes Net has delivered satellite products and services around the world, with more than 1.5 million systems ordered or shipped to customers in over 100 countries. Hughes Net services are sold directly throughout North America, Brazil, Europe, and India.
HughesNet is the brand under which Hughes Network Systems provides its one-way and two-way satellite broadband Internet technology and service in United States and Europe. Originally branded as DirecPC, it originally catered to business. In October 1996, it expanded into the consumer market, primarily targeting "work-at-home consumers who might otherwise use ISDN".It officially changed its name on March 27, 2006. In other regions of the world, Hughes products and services are available from a growing family of authorized service providers and resellers.
HughesNet satellite services are limited in function and usability. Latency is usually in the 750-1500ms range, which makes using many applications difficult or impossible. HughesNet implements a Fair Access Policy (FAP), which restricts the amount of bandwidth the user is allowed to use in any 24-hour period. This bandwidth limit is defined by the usage plan selected. 200-400 MB is the common limits in the residential packages. If this limit is exceeded, the connection is throttled to speeds slower than dial-up for 24 hours. The service is oftentimes rendered completely unusable by this throttling.
Signal latency
Satellite Internet access via VSAT in Ghana
Latency 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 received at its destination. Compared to ground-based communication, all geostationary satellite communications experience high latency due to the signal having to travel 35,786 km (22,236 mi) to a satellite in geostationary orbit and back to Earth again. Even at the speed of light (about 300,000 km/s or 186,000 miles per second), this delay can be significant. If all other signaling delays could be eliminated it still takes a radio signal about 250 milliseconds, or about a quarter of a second, to travel to the satellite and back to the ground. 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 milliseconds latency for the total Round Trip Time (RTT) back to the user. This is much more than most dial-up users experience at typically 150–200 ms total latency.
This inherent latency makes Satellite Internet service essentially unusable for applications requiring real-time user input, such as online games or remote surgery. This delay can also be irritating and debilitating with interactive applications, such as VoIP, videoconferencing, or other person to person communication. It will cause most general market applications (such as Skype) to behave unpredictably and fail, as these are not designed for the difficult compensation for the high latency connections. As research has repeatedly demonstrated that perceived delays in answering questions subconsciously suggests doubt to the listener and can generate mistrust even when both sides are aware of the lag[citation needed] , geostationary connections are best avoided for important voice calls. Other research[citation needed] into interactive systems has repeatedly demonstrated that latency lag is the most debilitating and irritating of all interactive system flaws and often gives an extremely negative impression of the system or its usefulness. Some researchers have gone so far as to recommend simply refusing connections to those with latency likely to result in poor interactive user experience.
The functionality of live interactive access to a distant computer can also be subject to the problems caused by high latency. However these problems are more than tolerable for basic email access and web browsing, and in most cases are barely noticeable. This is not true, however, for character-by-character command shell or virtual private networks (which typically involve several round trips using layered protocols) which are almost universally unusable through geostationary connections. Typical VPN connections made over satellite will be at least double (and often, with poor protocols and misguided security measures) quadruple or worse the underlying basic latency.. Unless the VPN is literally re-engineered to accommodate high-latency users, it will be useless for anything but email, download and a static web.
For geostationary satellites there is no way to eliminate latency, but the problem can be somewhat mitigated in Internet communications with TCP acceleration features that shorten the round trip time (RTT) per packet by splitting the feedback loop between the sender and the receiver. Such acceleration features are usually present in recent technology developments embedded in new satellite Internet services.
Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellites do not have such great delays. The current LEO constellations of Globalstar and Iridium 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 proposed O3b Networks MEO constellation scheduled for deployment in 2010 would orbit at 8,062 km, with RTT latency of approximately 125 ms. The proposed new network is also designed for much higher throughput with links well in excess of 1 Gbps (Gigabits per second).
A proposed alternative to geostationary relay satellites is a special-purpose solar-powered ultralight 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. Onboard batteries would be charged during daylight hours by solar panels covering the wings, and would provide power to the plane during night. Ground-based satellite 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 then run forever without refueling. Several such schemes involving various types of aircraft have been proposed in the past.
A foldable Bigpond Satellite Internet dish
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. 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 produce a more intense transmission on the uplink.
Modern consumer-grade dish antennas tend to be fairly small, which reduces the rain margin or increases the required satellite downlink power and cost.
Large commercial dishes of 3.7m to 13m diameter are used to achieve large rain margins and also to reduce the cost per bit by requiring far less power from the satellite.
Modern download DVB-S2 carriers, with RCS feedback, are intended to allow the modulation method to be dynamically altered, in response to rain problems at a receive site. This allows the bit rates to be increased substantially during normal clear sky conditions, thus reducing overall costs per bit.
Fresnel zone. d is the distance between the transmitter and the receiver, b is the radius of the Fresnel zone.
Typically a completely clear line of sight between the dish and the satellite is required for the system to work. 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.
The radio signal width between two ground satellite dish receivers is not perfectly straight and uniform, as if it were a beam of light. Instead as the signal propagates away from the transmitting dish, it widens towards the centerpoint between the two dishes and then narrows again as it approaches the receiving dish. This is known as the fresnel zone, and limits the usefulness of satellite dishes in locations where there is extremely limited open sky for signal reception. The signal path through space must be clear not only for direct line of sight, but must also be clear for the expanding fresnel zone, which may be several meters larger in diameter than the ground-based satellite dish.
The back panel of a satellite modem, with coaxial connections for both incoming and outgoing signals, and an Ethernet port for connection to the internal network.
Two-way satellite Internet service involves both sending and receiving data from the remote VSAT site via satellite to a hub 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. Some providers oblige the customer to pay for a member of the provider's staff to install the system and correctly align the dish—although the European ASTRA2Connect system encourages user-installation and provides detailed instructions for this. Many customers in the Middle East and Africa are also encouraged to do self installs. 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 (TDMA) and single channel per carrier (SCPC). Two-way systems can be simple VSAT 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. The modems 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 ASTRA2Connect.
The two-way "iLNB" used on the ASTRA2Connect terminal dish has a 500 mW transmitter and single-polarity receive LNB, both operating in the Ku band. Pricing for Astra2Connect 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 cumbersome and very expensive. The technology for ASTRA2Connect was delivered by a Belgian company called Newtec.
The Tooway satellite modem
Satellite internet customers range from individual home users with one PC to large remote business sites with several hundred PCs.
Home users tend to make use of 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 Mbytes allowances, 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 17,000 MB per month. A shared download carrier may have a bit rate of 1 to 40 Mbit/s and be shared by up to 100 to 4000 end users. Note that the average bit rate per end user PC is only about 10 - 20kbit/s.
The uplink direction for shared user customers is normally TDMA, which involves transmitting occasional short packet bursts in between other users (similar to how a cellphone shares a cell tower)
Business users tend to opt for dedicated bandwidth services where any congestion is under their local control.
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 transfers.
In 2006 the European Commission sponsored the UNIC project which aims at developing 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 standard for downlink and DVB-RCS standard for uplink.
Normal VSAT dishes (1.2 - 2.4m dia) 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.
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 or Universal serial bus. Some also have an integrated Bluetooth transceiver and double as a satellite phone. The modems also tend to have their own batteries so they can be connected to a laptop without draining its battery. The most common such system is INMARSAT's BGAN—these terminals are about the size of a briefcase and have near-symmetric connection speeds of around 350–500 kbit/s. Smaller modems exist like those offered by Thuraya but only connect at 144 kbit/s in a limited coverage area.
Using such a modem is extremely expensive—bandwidth costs between $5 and $7 per megabyte. The modems themselves are also expensive, usually costing between $1000 and $5000.
For many years now satellite phones have been able to connect to the internet. Bandwidth varies from about 2400 bit/s for Iridium network satellites and ACeS based phones to 15 kbit/s upstream and 60 kbit/s downstream for Thuraya handsets. Globalstar also provides internet access at 9600 bit/s—like Iridium and ACeS a dial-up connection is required and is billed per minute, however both Globalstar and Iridium are planning to launch new satellites offering always-on data services at higher speeds. With Thuraya phones the 9600 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 phones can be connected to a laptop or other computer using a USB or RS-232 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 data and using other low-bandwidth protocols. Since satellite phones tend to have omnidirectional antennas no alignment is required as long as there is a line of sight between the phone and the satellite.
One-way terrestrial return satellite Internet systems are used with traditional dial-up access to the Internet, with outbound data traveling through a telephone modem, but downloads sent via satellite at a speed near that of broadband Internet access. 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 involves the use of General Packet Radio Service (GPRS) for the back-channel.By utilizing a connection that is offered in standard GPRS or EDGE, the upload volume is very low and since this service is not per-time charged, but charged by volume uploaded, users are able to surf and download in broadband speeds. Another view of using GPRS as return would be the mobility when the service is provided by a satellite that transmits in the field of 50 to 53 dBW. Using a 33 cm wide satellite dish, a notebook and a normal GPRS equipped GSM phone, users can get mobile satellite broadband.
The transmitting station (also called "teleport", "head end", "uplink facility", or "hub") has two components:
* Internet connection: The ISP's routers connect to proxy servers which can enforce quality of service (QoS) bandwidth limits and guarantees for user traffic. These are then connected to a DVB encapsulator which is then connected to a DVB-S modulator. The radio frequency (RF) signal from the DVB-S modulator is connected to an up converter which is connected via feed line to the outdoor unit.
* Satellite uplink: The block upconverter (BUC) and optional low-noise block converter (LNB), which may use a waveguide to connect to the optional orthomode transducer (OMT) which is bolted to the feed horn which is connected by metal supports to the satellite dish and mount.
At the remote location (Earth station) the setup consists of:
* Outdoor unit
o Satellite dish with mount
o Feedhorn
o Universal LNB, for Ku-band.
o Feed line
* Indoor unit
o DVB-S Peripheral Component Interconnect (PCI) card internal to a computer
o or, DVB external modem where an 8P8C (RJ-45) Ethernet port or a Universal Serial Bus (USB) port connects the modem to the computer
Remote sites require a minimum of programming to provide authentication and set proxy server settings. Filtering is usually provided by the DVB card driver.
Often, non-standard IP stacks are used to address the latency and asymmetry problems of the satellite connection. 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 do not need to accept the latency inherent in a satellite connection. For similar reasons, there exist special Virtual private network (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, and latency is high, as it is for any satellite based Internet (minimum of 240 ms one-way, resulting in a minimum round-trip time of almost 500ms). Download speeds can be very fast compared to dial-up.
Remote sites use proxy server or(and) Virtual private network servers at the earth station (teleport), which is configured to route all outbound traffic to the QoS server, which makes sure no user exceeds their allotted bandwidth or monthly traffic limits. Traffic is then sent to the encapsulator, which puts the IP packets inside of DVB packets. The DVB packets are then sent to the DVB modem and then to the transmitter (BUC)
One-way multicast satellite Internet systems are used for Internet Protocol (IP) multicast-based data, audio and video distribution. In the U.S., a Federal Communications Commission (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.
Similar to one-way terrestrial return, satellite Internet access may include interfaces to the public switched telephone network for squawk box applications. An Internet connection is not required, but many applications include a File Transfer Protocol.
Most one-way multicast 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.
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. These types of technologies are generally referred to as TCP acceleration, HTTP pre-fetching and DNS caching.
While also effective for terrestrial communications, the use of ad-blocking software such as Adblock for Firefox is exceptionally beneficial for satellite Internet, as most Internet advertising websites use cache busting in order to render the browser and ISP's cache useless, by displaying advertisements (for the purpose of maximizing the number of ad views seen by the affiliate marketing company's server).
SkyTerra-1 was launched in mid-November and will provide service across North America while Hylas-1 was launched at the end of November and will target Europe. And at December 26, 2010, Eutelsat's Ka-Sat was successfully launched by an ILS Proton Breeze M vehicle at the Baïkonour Cosmodrome Kazakhstan. The last satellite is due in service in 2011 and is the third broadband Internet satellite to be launched in the last six weeks. It will cover the 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 will have an overall capacity of 900Mbps and the entire satellite will have a capacity of 70Gbps.
Hughes Network Systems
A wholly owned subsidiary, Hughes Network Systems is a provider of broadband satellite network products for businesses and consumers. Headquartered outside Washington, D.C., in Germantown, Maryland, USA, it maintains sales and support offices worldwide and employs approximately 1,500 people in engineering, operations, marketing, sales and support. It also operates manufacturing facilities in Gaithersburg, Maryland. It first opened its doors in 1971 as Hughes Electronics, which expanded in 1987 with the purchase of M/A-COM Telecommunications. In January 2003, the company was sold to SkyTerra Communications. Hughes pioneered the development of high-speed satellite Internet services, which it markets globally under the “Hughes Net brand. Hughes Net has delivered satellite products and services around the world, with more than 1.5 million systems ordered or shipped to customers in over 100 countries. Hughes Net services are sold directly throughout North America, Brazil, Europe, and India.
HughesNet is the brand under which Hughes Network Systems provides its one-way and two-way satellite broadband Internet technology and service in United States and Europe. Originally branded as DirecPC, it originally catered to business. In October 1996, it expanded into the consumer market, primarily targeting "work-at-home consumers who might otherwise use ISDN".It officially changed its name on March 27, 2006. In other regions of the world, Hughes products and services are available from a growing family of authorized service providers and resellers.
HughesNet satellite services are limited in function and usability. Latency is usually in the 750-1500ms range, which makes using many applications difficult or impossible. HughesNet implements a Fair Access Policy (FAP), which restricts the amount of bandwidth the user is allowed to use in any 24-hour period. This bandwidth limit is defined by the usage plan selected. 200-400 MB is the common limits in the residential packages. If this limit is exceeded, the connection is throttled to speeds slower than dial-up for 24 hours. The service is oftentimes rendered completely unusable by this throttling.
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