Transfers of large amounts of data across the Internet to wireless devices suffer from a key problem: The Transmission Control Protocol (TCP) used to send and receive that data can be unnecessarily slow.
A company called Aspera has now announced an alternative protocol designed to accelerate wireless transfer speeds. Called fasp-AIR, it includes new proprietary approaches to addressing problems of data transfer that are unique to wireless communications. The original fasp protocol is already used to boost regular Internet transfers. It was used, for instance, to speed up the transfer of files from New Zealand to the U.S. during production of the movie Avatar.
The main problem with the TCP protocol, which was designed before wireless connections to the Internet were commonplace, is that it doesn’t know the difference between packets of data that are lost because of network congestion and those that are lost because of a weak wireless signal. TCP automatically throttles the speed of data transfer when it sees dropped packets, so that congestion doesn’t overwhelm the network. That’s fine when packets are lost because of congestion, but when the problem is a weak signal, it causes an unnecessary drop in transfer speeds that can bring downloads and uploads to a crawl.
For some applications, like streaming video and Internet telephony, it’s possible to use an alternative like the User Datagram Protocol (UDP), which doesn’t bother to confirm that all data has arrived intact. The price of UDP’s speed is dropped packets of data–a result familiar to anyone who has endured the degraded quality of a video stream or telephone conversation when at the limits of a wireless network’s range.
Fasp-AIR achieves faster speeds than TCP but doesn’t result in any dropped packets, making it suitable for transferring data that must arrive complete and intact. “The drop-off in performance we see with fasp-AIR is almost linear,” says Aspera CEO Michelle Munson. “So a 10 percent loss in the available bandwidth means we’re still getting transfer rates that are 90 percent of what’s specified.”
At first, fasp-AIR will be available as an iPhone app that can be used to access enabled servers. Fasp-AIR requires that both the client and the server are running software developed by Aspera. In the future, Aspera hopes that developers will incorporate fasp-AIR into their applications directly. Aspera licensees currently include Amazon and several other large Internet companies.
Fasp-AIR certainly isn’t the only novel approach being used to speed up transfers of wireless data. Jon Crowcroft, Marconi Professor of Communications Systems at the University of Cambridge, says that some wireless carriers use a proxy server between the wireless and the wired networks to intelligently adapt to changing network conditions. This gets around the problem of whether or not a TCP alternative like FaspAIR is hogging bandwidth on a congested network.