When Cairncross (1997) wrote about the death of distance, he must surely have been referring to the capacity of satellite systems to render geography meaningless. There are two primary satellite system technologies, differentiated according to the height of their orbit. These are Geosynchronous Earth Orbit Satellites (GEOs) and Low Earth Orbit Satellites (LEOs). Apart from these two, a nascent third alternative is stratospheric telecommunications services.
As the name suggests, these satellites remain in the same position over the earth's surface. To do so, the satellite's orbit must be at a specific height within the Clarke belt, which is about 22,000 miles above the equator. A single geostationary satellite can "see" approximately 40 percent of the earth's surface. A geostationary satellite can be accessed using a dish antenna aimed at the spot in the sky where the satellite hovers.
Hughes Network Systems DirecPC is probably the best known satellite system covering North America. Users in remote areas can subscribe to the DirecPC service as long as they enjoy a clear line of sight to the southern sky. Setting up DirecPC Internet access would require an antenna, a satellite modem and DirecPC Satellite Access software (included with the satellite modem).
The cost of installation is $200 and the monthly service fee is $30. Downstream data rates are as high as 400 kilobits/second. Regular telephone lines carry upstream data. DirecPC provides an alternative in remote rural areas. The USDA/NTIA (April 2000) report states, "Because DirecPC provides customers in the most remote rural areas with the same quality of service provided to those in urban areas, it provides a preview of the potential for satellite broadband to eliminate geography and location as a cost factor" (page 17).
Two new Ka-band commercial geostationary satellite systems being designed to provide Internet access to small-business and residential users are iSky and NetSat28. NetSat28, however, will only target small businesses, home office and high-end residential users.
Besides all these new systems, a number of satellite service providers are upgrading their initial one-way Internet access offerings into two-way services. One such system is Hughes Network Systems' DirectPC, a spin-off from its digital direct-to-home TV service, DirecTV.
Low earth orbit satellites do not remain in a stationary position above the earth's surface. They constantly orbit between a height of 450 and 700 miles. LEOs essentially function as part of a fleet of "birds" constantly revolving in such a way that at any time at least one satellite is within line of sight from any point on the earth's surface. The ill-fated Iridium network, for example, consisted of 66 constantly moving satellites, each of which covered a particular area for only a few seconds. The Iridium network, through a contract with Motorola, provided wireless voice, data, fax and paging services with global roaming facilities. Although it was a technical marvel in its time, mismanagement and unrealistically high initial pricing forced Iridium into bankruptcy and led to the decommissioning of the satellite network. Another often cited reason for the failure of Iridium's narrowband mobile satellite services is the increasing demand for broadband data services.
SkyBridge and Teledesic are putting the newest generation of LEO broadband satellites into orbit. Teledesic plans to build a LEO system of 288 satellites, which will start service in late 2004. The cost of setting up these constellations will run into billions. Given the bankruptcy of Iridium, the future off these ventures is a little uncertain. When asked about the future of LEO satellite systems David Finkelstein, senior vice president of marketing and business development at SkyBridge is quoted as saying, "We still think there will be enough low-hanging fruit, especially in rural areas, since deployment of fiber is so heavily concentrated in cities." Headed by French telecommunications giant Alcatel, SkyBridge plans to begin offering Ku-band LEO satellite service in 2002. SkyBridge claims to be a solution for last mile connectivity - especially in rural America and other less developed parts of the world.
The VSAT consists of two modules - an outdoor unit and an indoor unit. The outdoor unit consists of an Antenna and Radio Frequency Transceiver (RFT). The antenna size is typically 1.8 meters or 2.4 meters in diameter, although smaller antennas are also in use. The transceiver receives or sends a signal to a satellite transponder in the sky. The indoor unit (IDU) is the size of a desktop computer and functions as a modem that also interfaces with end user equipment like stand alone PCs, LANs, telephones or an EPABX. VSAT is used both by home users who sign up with a large service such as DirecPC and by private companies that operate or lease their own VSAT systems.
The USDA and NTIA report titled "Bringing Broadband to Rural America" mentions Tachyon, a broadband data satellite system that uses VSAT technology. Tachyon connects end users to their ISPs using satellite links This promises to help ISPs reach customers in rural areas. Network traffic is carried via satellite between Tachyon Access Points (TAPs) at subscriber premises and a satellite. The TAP is a small outdoor unit comprised of a small satellite dish (less than one meter in diameter) that sends and receives satellite data. An indoor Tachyon network server consists of a PC enclosure with a custom satellite modem connected to subscriber LAN equipment via a 10/100BaseT Ethernet interface and standard Internet protocols.
Image Source: BhartiBT, "What is a VSAT"
A+Net Internet Services is one ISP that uses Tachyon's satellite links to connect to their end users. Their pricing chart is as follows:
|Service Level||Base (1)||Enhanced (2)||Premium(3)||Exceed Bandwidth Allotment|
A+Net Setup and Tachyon Access Point (TAP) installation is $995. A TAP could be set up in conjunction with a rooftop community network, in remote rural areas that cannot set up an Internet radio link to the nearest ISP.
In rural areas in the US, wireless is an alternative to making expensive long distance calls to connect to commercial ISPs. Based in Fremont, CA, Intellicom, provides high speed, two-way, satellite connections for ISPs and schools, like the University of Illinois at Urbana-Champaign, the Marshall Community Unit School District in Illinois, and Cibola Internet Systems. The entire system, once procured, can be set up within 24 hours at a cost of $33,000 for installation and service. Monthly fees are $1700 for the fastest service that has uplink speeds of 66Kbps and downlink speed of 2Mbps.
Marshall, IL, is a rural town located several hours from any major city. Due to the costs associated with long-distance leased lines, the district decided to explore other alternatives. They elected to use Intellicom's bi-directional satellite link to provide Internet access to the school and all residents of the district. The district has satellite dishes installed at two locations. The first dish is located at the high school, with a coaxial cable connecting the junior high to the high school. This allows both buildings to share access to the Internet. The second dish is located at the elementary school and provides Internet access for the building.
The district has also installed a dial-in modem pool with ten modems attached to it. In addition to offering after hours access to the district staff, they are reselling access to the community to offset the cost of the satellite network. The network configuration is as depicted below.
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