WANS in the sky

Communications satellites can do a lot more than broadcast live television or handle global phone calls. These days, satellite companies are marketing services to corporations to facilitate WAN links and business broadcasts.

“Satellite communications can handle essentially any application that exists today, whether it be Internet-based or a legacy-type application like voice and data, connecting computers and LANs,” said Michael Martin, director of business development for Telesat, Canada’s national satellite communications company, in Gloucester, Ont.

Martin explained the capacity of a satellite is determined by its transponders, which can handle a specific amount of information. But because of compression technology and other advancements, Martin said the amount of data a transponder can manage is always increasing.

“Anything you can do on terrestrial networks can also be done on satellite. [Also], satellites have the advantage of being able to provide service anywhere within the footprint of the satellite,” he said.

A satellite’s footprint is the area of earth it covers. Telesat’s Anik E satellites currently cover all of Canada and parts of the United States, but upcoming launches of Nimiq and Anik F1 will eventually give coverage over all of North and South America, Martin said.

Telesat’s satellites are geostationary, meaning they sit in a fixed orbit about 36,000 kilometres above the equator. That equatorial band has become “prime real estate,” Martin said.

“It is getting very crowded, and it’s up to satellite operators to make sure they coordinate their plans, their footprints, their use of frequencies,” Martin said.

So when a new satellite is launched, old satellites have to be shuffled around. Martin said, for example, when Anik F1 is launched it will replace Anik E2, which will then be used as back-up capacity. But eventually, satellites run out of fuel and have to be junked, Martin said. Enough fuel is saved to jettison the satellite into a higher orbit where it drifts farther and farther from earth, eventually drifting off into space.

worldwide distribution

The limitation of a geostationary satellite, according to Bob Egan, research director with Gartner Group Inc. in Stamford, Conn., is the lag time of just more than a second it takes to transmit data that far up and wait for it to come back down.

“So for interactive Internet access, even if you applied a lot of bandwidth, the physical constraints due to the positioning of the satellite will make this latency-bound,” Egan said. He said geostationary satellites are very good for broadcasting large amounts of data.

“That’s why car dealerships use it or financial institutions, so they can very quickly, very fairly distribute large amounts of data on a worldwide basis. Movie distributors and software suppliers are beginning to look at this technology using multicast IP to distribute large software updates or deliver the movie itself,” Egan said.

Geostationary satellites are not sensitive to weather, Egan added, and they have 99.9-per-cent reliability. However, he said the future could be very different due to emerging medium earth-orbiting (MEO) and low earth-orbiting (LEO) satellites. As satellites move closer to earth, the lag time disappears, but they become more sensitive to weather patterns.

Companies such as SkyBridge, headquartered in Washington, D.C., are planning to put broadband applications and Internet access on LEOs in the next few years. SkyBridge’s network will be a constellation of 80 LEOs orbiting at 1,469 kilometres.

Herve Sorre, vice-president of business development for SkyBridge in Canada, said the company is still in discussions with potential partners, and none of the satellites are yet built.

“The delivery of the first satellites will be in 2001, which means we will have worldwide operation in 2002,” Sorre said.

But Egan said an operational date of 2002 might be too optimistic.

“Realistically, we won’t see an Internet-in-the-sky type of service at least until 2004,” Egan said, adding there are many factors companies such as SkyBridge haven’t considered.

“How many satellites have they built? What are their scheduled launch dates? What licence do they have in place? Who are the service providers who have signed up to deliver and support this service? What about help desks and call centres and billing? You start asking those questions and they’re still thinking about the antenna size,” Egan said of broadband LEO network vendors in general.

Sorre said SkyBridge’s target retail costs for the user dishes range from US$700 for a small residential terminal to around US$2,000 for a larger business terminal. The small terminal will have a downlink of up to 20Mbps and an uplink up to 2Mbps; the larger terminals’ speeds have not yet been determined, Sorre said. He said there will likely be a monthly charge for usage, but that will be left up to the service providers.

Once the system is up, Sorre said, he expects LEO broadband providers to be able to capture the approximate 20 per cent of residential and business markets that are estimated to not have sufficient terrestrial services available.

“Canada is an interesting market because of the geography of the country…The beauty of satellites is with a network in the sky you get global coverage, so you can reach any user anywhere,” Sorre said.

“Satellites are not going to replace traditional networks. We’re positioning ourselves as another technology in addition to the telephone technologies which are starting to be deployed today.”

Telesat’s Martin said his company’s services are well suited to Canada’s remote regions as well, and services are available now.

“If you’re a mining or logging operation, or for some reason you have facilities in off-net locations, then satellite is your best network facility because you can provide ubiquitous service everywhere within the footprint of the satellite,” Martin said. Global access is also possible, he said, although Telesat would have to work with other telecommunications providers to achieve that additional linkage today.

“But if you ever drive by a car dealership…you’ll see a dish on the roof. That’s how they do their networking, and that’s how if you go in to buy a car and you say you want a purple one, they’ll look on their network, all connected by satellite,” Martin said.

Jim Cecile, manager of strategic technologies for Chrysler Canada in Windsor, Ont., said his company’s 600-dealer-site network relies on Telesat for communications to and from the factory and other dealers for vehicle orders, warranty claims, credit card authorizations and other needs.

“It’s reliable. When the satellite is out, it automatically dials into a land line, but for the most part our network has been up 99.9 per cent of the time,” said Cecile, adding he is very pleased with the service.

“It’s easy to add bandwidth. We’ve increased the amount of data that we send back and forth to the dealers in the past few years four-, five-, sixfold.”

Cecile said the old land-line network made large broadcasts slow and cumbersome. He said broadcasts range in time from 10 minutes to two hours, and dealers used to activate the download and just wait. But the system could only handle 50 to 60 dealers at a time, so the others would have to wait to even start the download.

“Now we go in the middle of the night and broadcast a two-hour download to 600 dealers simultaneously,” Cecile said.

broad coverage

Gartner’s Egan said there are several good reasons for corporations to consider using satellite technology for their WANs.

“IT managers should consider broadband satellite technologies to deliver services into what I call bandwidth-challenged areas, where there’s a lack of mature high-band terrestrial alternatives. Consider satellites when you have a centralized organization with lots of international points of presence where you have to deliver content and you need fair and reasonable access on an international basis.

“And consider satellites for contingency purposes against terrestrial failures, which I consider to be a major problem,” Egan said. He said terrestrial back-ups are good as well, but satellites should be considered as an alternative.

When choosing a possible satellite provider, Egan said, technical specifications such as the frequency band are not the important facts.

“What they (customers) should be defining is what their bandwidth requirements are, what their latency requirements are and what their distribution requirements are, and let the satellite provider come back and put together a network topology with those requirements at a given cost,” Egan suggested.

“Generally, a good guideline is if you have a remote site and your requirements are not for broadcast but for interaction, once you get up to about 10 or 12 users in a typical client/server-type scenario, then you start to need to get creative,” Egan said.

“That means that maybe you put a server between your end users and the satellite so that your end users are really interacting with the server over high-speed Ethernet, and the server is doing continuous synchronization between its database over the satellite link back to the centralized database. So it gives the people the feel of real time, even though they’re not (interacting in real time),” Egan said.

Because of the flexibility of satellite offerings, Egan said, a company can invest as much or as little as it needs to depending on its requirements for information currency, bandwidth and latency.

As for security, the fact remains that anyone who can point a receiver towards the sky can intercept transmissions, Egan said. For that reason, enterprises should control their own end-to-end encryption and not rely on outsourcing.

Given that both Canadian and U.S. defence forces use satellites, however, Telesat’s brochures state the technology is capable of high levels of security beyond simple signal encryption.