To the orbit and back
Satellite communications find a niche in the military and emergency services
- By Paul Korzeniowski
- Jun 20, 2005
Editor's note: This is part 2 of a three-part series on networking. Part 1 focused on efforts to consolidate networks. It can be found on FCW.com Download’s
Data Call at www.fcw.com/download. Next week's article will focus on telecommunications strategies.
The Federal Emergency Management Agency has nine vans outfitted with satellite dishes and computers that it uses to help local and state agencies in disaster areas coordinate rescue and restoration operations.
For example, as hurricanes battered the Florida coast last summer, FEMA officials wanted to establish emergency response centers as quickly as possible.
"Because we need our communications lines up so fast, satellite communications are our best option," said Rex Whitacre, chief of information technology district operations at FEMA.
FEMA is just one example of government agencies that rely on satellite communications. "There have been a few times when vendors tried to position satellite as a head-to-head competitor with terrestrial lines, but they eventually backed off from such statements," said Christopher Baugh, president of market research firm Northern Sky Research.
Instead of being used in widespread deployments, satellite communications have proven popular in three situations: when rapid deployment is needed, when no other telecommunications options are available or when an agency wants to have a backup option if its terrestrial link goes down.
Whitacre said satellites are suited to quick installations. Unlike terrestrial lines where deployment can take days, weeks or months, satellite lines can be up and running in a few days. Also, there is no work required on the provider's end, so the process requires only that the user install the satellite dish and connect it to its enterprise network. Government research organizations, particularly those tracking environmental and military issues, also may need new communication lines set up quickly.
Satellites are often the only communications option for agencies in rural areas. Terrestrial carriers have to undertake a cost justification process whenever they want to expand their networks. Typically, they only string new lines in densely populated areas because it doesn't make economic sense to run miles of fiber when there are only a few dozen potential customers.
Satellite technology does not have the same constraint. Because of their point-to-multipoint configuration, satellites transmit signals that can be picked up worldwide.
Government agencies that test various defense systems, monitor wildlife and energy resources, track the weather or provide emergency services often work in areas where there are no terrestrial lines so they rely on satellites to transmit information.
The military is a major user of satellite communications, especially for personnel who are stationed in remote locations where traditional telecom tools are out of reach.
One of the Army's challenges in Iraq is making sure that troops have the spare parts needed to keep their artillery and munitions operational. Soldiers have traditionally entered product requests into laptop computers and then passed the information to others further down the supply chain to move data from the field to Army warehouses. This process can take a few hours to months, depending on where the soldiers are stationed.
The Army conducted a pilot program last spring that outfitted soldiers with satellite transmitters that let them send this data electronically.
"The replenishing forces now have a better idea of where the troops are located and can move themselves closer to make the retooling process smoother," said Maj. Michael Devine, an Army assistant product manager.
The Sept. 11, 2001, terrorist attacks spurred agency interest in satellite services. "Government agencies now need disaster recovery plans that take into account the possibility that a central office can be wiped out," said Jeff Carl, director of marketing at Spacenet. Consequently, using alternative carriers won't work, but satellite links will, he said.
Users understand that satellite links have evolved from carrying data only to a mix of data, voice and video traffic. Video is a natural enhancement, and many satellite networks' primary function is to carry video traffic for cable and satellite TV services.
Recently, there has been growing interest in running voice over IP over satellite links. "There are more users working with VOIP applications than we anticipated," said Karl Fuchs, senior systems engineer at iDirect Technologies. "In some cases, it represents 90 to 95 percent of the traffic running over our satellite links." These users don't seem to be deterred by satellite call quality, which can resemble cellular connections.
Yet vendors still face a number of hurdles in their quest to expand their customer bases, especially when it comes to price. Although FEMA officials understand the value of satellite services, the bulk of its data, video and voice communications run on terrestrial lines.
"I can get a terrestrial T1 line for about $1,500 to $1,800 a month, and a comparable satellite link costs about 10 times as much," Whitacre said.
Prices for satellite communication service have been going down, and new consumer services, such as Internet access, are becoming comparable to terrestrial services, but satellite equipment pricing is still higher than terrestrial line costs.
At most, a government agency will pay a few hundred dollars for terrestrial equipment, which is often bundled in with services such as DSL. Terrestrial equipment is also fairly easy even for end users to install. In comparison, prices for satellite systems range from $1,000 to $5,000 per site, and only skilled technicians are able to deploy them.
Volume is another reason for the difference in equipment pricing. Terrestrial lines are used by many individuals and businesses, so network equipment vendors have been able to drive volume up and pricing down. Wired telecom services generate hundreds of billions of dollars in revenue annually in the United States, while satellite suppliers make only a few billion dollars.
An allegiance to proprietary protocols has also increased pricing. Although satellite vendors have moved to standard protocols, such as IP, they have not embraced those standards broadly. Three options are vying to become the standard for carrying IP traffic over satellite links.
The higher equipment expenses also stem partly from the difficulties that arise with the extra engineering work required with satellites. The pairing of IP and satellite networks is an unnatural one. A satellite link travels from a user's desktop to a network switch to a very small-aperture terminal (VSAT) basically a satellite dish that exchanges information with a spacecraft orbiting the earth 22,300 miles away.
Each time a data packet is shipped, it travels up from the sending system to the orbiting satellite and then back down to a receiving dish. The time needed to make the trip translates into one-quarter of a second. The framing, queuing and switching that the TCP/IP system relies on to ensure that packets arrive at the proper destination can increase that time to as much as half a second.
TCP/IP was designed for networks where delays are measured in milliseconds rather than tenths of seconds, so satellite delays can disrupt the acknowledgments and handshakes that are at the core of the network protocol.
When a transmission becomes garbled, TCP/IP adapts by slowing down. In a satellite network, that can mean that transmissions slow to a crawl.
"We can't alter the laws of physics, but we have found ways to mitigate the impact of delays," said Michael Cook, senior vice president at Hughes Network Systems. For example, packet spoofing fools a sending system into thinking it has received acknowledgments for shipped packets so that it continues to transmit data steadily.
In addition, satellite vendors have to account for physical and weather interference. Users and vendors have to make sure that they have a clear line of sight for transmissions.
In some instances, a company makes changes such as adding onto its office building or planting trees that block sight lines, forcing customers to move their satellite dishes or convince their neighbors to change something.
Heavy rain or snow can also slow transmissions and increase the number of dropped packets.
"We didn't have more than a minute or two when weather knocked our systems off-line during the hurricanes last summer," said John Fleming, a senior manager at Florida's Division of Emergency Management, which relies on satellite services to connect 140 sites statewide.
Although vendors have developed various schemes to address latency and weather problems, such techniques often add overhead to data transmissions, which lowers throughput.
The overhead also exacerbates a lack of bandwidth with satellite networks. Terrestrial carriers are upgrading their fiber-optic backbones to OC-192 links, which transmit data at up to 10 gigabits/sec, while satellite lines typically top out at 45 megabits/sec.
The bandwidth constraints are most evident when companies try to upload information. Unlike most terrestrial services, satellite services support different transmission rates for uploads and downloads.
Satellite networks were optimized for video transmissions, where complex images are shipped to tens, sometimes hundreds, of endpoints with little, if any, data sent up from those end stations. As a result, download speeds can be up to 20 times faster than upload rates.
Because of the limitations, satellite technology is expected to remain a niche rather than a mainstream application.
"Satellite services will experience slow and steady growth about 4 percent to 5 percent per year rather than the sharp and dramatic uptick in usage that would be needed to make it more of a threat to terrestrial lines," Baugh said.
Korzeniowski is a freelance writer in Sudbury, Mass., who specializes in technology issues. He can be reached at firstname.lastname@example.org.