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Taking compression wireless

Dec 03, 20032 mins
Cellular NetworksNetwork SecurityUtilities

* Getting more out of your satellite link

Today, there are powerful compression tools for squeezing greater efficiency out of existing WAN links, rather than buying more bandwidth. Most are double-ended, meaning you need one at each end of a connection to work.

In the wired world, Expand Networks participates in this space alongside companies such as BoostWorks, ITWorx and Peribit Networks. But it has also taken its technology wireless. Most recently, Expand has struck some agreements for getting is Accelerator compression technology bundled into products that work with mobile satellite connections.

Compression over satellite and other mobile WAN links is probably more useful than anywhere. Satellite already has uplink/downlink delay to contend with, for example, so anything that can be done to otherwise improve the efficiency of satellite communications is desirable.

Expand OEM partner EMS Technologies has released a product called the Cabin Network Xcelerator that attaches to an airborne device, such as a business jet, and communicates via satellite with an Expand-based terrestrial product that EMS private labels as the Xstream 4800. The setup reportedly increases mobile satellite bandwidth capacity by 100% to 400%, the general throughput improvements that Expand claims with its entire Accelerator compression product line.

For “fixed” satellite connections, Expand Accelerators sit on the LAN side of an enterprise’s WAN access router. The router connects to a satellite modem, which connects to the very small aperture terminal that communicates to the satellite.

Accelerator compression devices used with satellite links have been outfitted with tricks to overcome high latency, says Ariel Shulman, Expand vice president of business development. He says the devices recreate lost packets, when necessary, rather than retransmitting them.

Retransmissions take 500 to 600 milliseconds, so it’s best to ignore a small amount of packet loss or recreate the packet rather than suffer the delay, he says.

In addition, when no data is being sent on the satellite link, users often would like to drop the link to save money. “On a terrestrial link, we send health-check packets. We adjusted that for satellite so that the checks are transmitted when the link is up but drop off when no data is being sent.”

The ExpandOS operating system runs on Expand’s three Accelerator platforms. “The satellite capabilities are in all the OS versions, but are different among platforms, optimized for different-speed connections,” Shulman explains. “Users simply choose to enable or disable them.”