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Contents Background Satellite Data Services Services Technology Summary Illustrations ISP Uplink, Satellite Downlink Satellite Uplink, Satellite Downlink Printer friendly version Future of Satellite-based Broadband (PDF file; 5 KB) Get Acrobat Reader To view Adobe PDF files, you need Adobe Acrobat Reader, which can be downloaded from the Adobe website.

Future of Satellite-based Broadband

Background

Traditional network access has been through physical circuits, from dial-up modems using phone lines to dedicated circuits such as 56K and T-1s. While early Internet access was primarily text-based and worked well over low-speed circuits, today's Internet services are multimedia-rich, with graphics, color, sound, and video. These media-rich services require high-speed access that is much faster than dial-up modems, creating a need for broadband services (i.e., any connection faster than 1 Mbps) to be widely deployed.

With many technologies, cost decreases in a vicious circle: cost drives need, need drives consumption, and consumption drives cost. As the need for a service increases, consumption increases, which drives costs down. When costs go down, availability can increase to meet need. The cycle drives itself. In many industries, this model works very well, but the telecommunications sector presents some unique challenges.

Among the challenges that telecommunications faces is that economies of scale are more difficult to achieve. Unlike retail sales, where the customer comes to the store and the cost to sell an item is the same regardless of where the customer lives, the telecommunications service must be delivered. Customers are scattered all over the country, from rural settings to dense urban areas. In urban areas, the customer density is high, so the amount of equipment and circuits that need to be built or upgraded to service a large group of customers is fairly small. In rural areas, however, there is more equipment for a much smaller number of customers, resulting in a much higher cost per customer.

Even in urban areas, access to high-speed services such as cable modems and DSL is not uniform. Many areas have cable and DSL, while just a few blocks away, other areas have neither. Combined with the high costs of deploying services to rural users, availability problems with broadband access add up to a reasonably large segment of the population with no ready, cheap access to broadband services.

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Satellite Data Services

To solve this access problem, several providers have begun offering satellite-based data services. By delivering the services via satellite, the issue of customer density per square mile is not important; a single satellite can handle the entire country. While there are pros and cons to this solution, it appears that for residential users, this method may provide an economical means to acquire broadband services. For business users, satellite-based services may be an answer in areas where no other services are available; however, business use is generally more demanding than residential use, and some of the limitations and issues may be unacceptable.

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Services

Currently, there are numerous companies offering satellite-based Internet services, although most of them are reselling the same services, sometimes with value-added features.

DirectTV's DirectWay (http://www.satcast.com/directway/) is primarily targeted at consumers. Equipment cost is between $600 and $900, including professional installation. Monthly costs range from $60 to $90, based on the options selected.

SkyCasters (http://www.skycasters.com/) is targeted at business users. SkyCaster uses the DirectWay system, but has an arrangement with Hughes Satellite to manage the QoS to guarantee performance. Equipment costs were not listed, but monthly fees ranged from $100 to $250.

StarBand (http://www.starband.com), part of the Dish Network, is targeted at residential and business users. Equipment costs start at $500, and professional installation is required (at an additional cost). Monthly fees range between $70 for residential users and $130 for businesses.

	Uplink	Downlink	Monthly	Install
Skycasters	128 Kbps burst (32-64 Kbps normal)	384 Kbps (750 Kbps and 1 Mbps available)	$100-250/month	Varies
DirectWay	Not listed	Not listed	$99/month	$99
StarBand	Not listed	500 Kbps	$70-130/month	$500

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Technology

There are two types of satellite-based Internet systems: downlink-only and two-way. Downlink only systems require that the user dial into his or her ISP for the uplink connection, while the return path, or downloaded data, arrives over the satellite (at much higher speeds than the dial-up connection).

Figure 1: Request sent via regular telephone connection

With a two-way system, both the uplink and the downlink are through the satellite, giving the user an always-on connection without tying up a phone line, which is more like regular land-based broadband.

Figure 2: Two-way satellite system

With either system, there are a number of issues that a user must be aware of:

1. Satellite systems have inherent delays due to distance. The satellite is in geosynchronous orbit, approximately 22,000 miles from the Earth's surface. Therefore, any signal has to travel up and back, for a total round trip of 44,000 miles, which causes a noticeable delay, or latency. This delay is about 250 milliseconds, or a quarter of a second, one way. To send a request and receive a response, the user will experience about one half second of latency. While the delay is not noticeable when receiving a data download (such as a file transfer) or watching a video stream, any interactive service (such as videoconferencing or voice over IP) will be adversely affected. With the round-trip time taking at least one half of a second, the video or audio interactivity is severely degraded as compared to wireline circuits (such as a T-1).
2. Satellite systems are "shared" networks. Like unswitched Ethernet, every use of the system consumes bandwidth; the more users there are, the less bandwidth there is for any single user. Unlike cable systems, though, where the competition is generally limited to a single "drop" area or neighborhood, the competition for satellite bandwidth is nationwide. So, as more users begin using the satellite service and more high-bandwidth streams for audio and video are transmitted, overall per user capacity will drop.
3. Satellite systems are very insecure. Since a user's data is beamed back to him or her, the data is susceptible to eavesdropping. While only the downloaded data is at risk, this is the data stream that will include account numbers, IDs, and other personal information. SSL and other encryption methods need to be implemented to protect data from being compromised. While eavesdropping is also a risk in wireline systems, eavesdroppers have to be in the data path to listen in. With satellite systems, eavesdroppers only have to be on the same continent.
4. Satellite systems cannot provide quality of service or bandwidth controls. In wireline systems, QoS can be controlled since each user has a separate entry point into the network. With a satellite system, all users beam their data to the satellite, which relays the data to the ground to be routed. Since there is no control on the amount of traffic a user can send, several high-bandwidth users can consume the satellite and effectively block other users. There are some rudimentary controls in place to provide some limits, and some vendors have proprietary solutions (e.g., SkyCasters) to provide some QoS, but these solutions are not as good as what today's wireline systems can offer.
5. Satellite systems require a clear line of sight to the satellite. Although it seems unlikely, there are areas where a clear view of the sky and the satellite is not available. Urban areas with tall buildings are a problem, as are rural areas close to mountains, bluffs, in valleys, and near other natural formations that may block the sky. In any location, other buildings, trees and a myriad of other obstacles may block enough of the sky to prevent the system from functioning.
6. Satellite systems require professional installation. Due to FCC regulations, a certified professional installer must install any two-way satellite system. This requirement increases the cost to subscribers who might be able to install the system themselves, and in many areas, there may not be an installer, so travel charges may apply.

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Summary

For users without access to cable modems or DSL service, especially in rural areas, satellite systems offer the only broadband solution today. However, the limitations will prevent satellite broadband from becoming the preferred connectivity method, and as DSL and EtherLoop services are pushed out to more customers, the long-term viability of satellite systems will continue to decline. Special services, such as business VPNs for a large number of sites, may see benefits from using satellite systems even after satellite's viability has substantially decreased.

For most MOREnet customers, satellite-based delivery systems would not be a good choice, as customers are moving more and more into multimedia applications and videoconferencing. Some customers who do not use real-time applications like VoIP and H.323-based video could be well-served by a high-quality satellite system, as long as the applications are known and the issues and limitations are understood. Individual districts may want to consider the service for outlying buildings where wireline services are either unavailable or unaffordable.

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