MIT Researchers Turn Heads With WLAN Tech: Coded TCP
Lee H. Badman
October 29, 2012
In the late 1990s, WLAN data rates up to 11 Mbps were impressive. For that matter, simply accessing the network over the air back then at any usable speed was impressive. Since those days, researchers and vendors have employed a variety of technologies to enhance data rates and make wireless networks more reliable. Just a few years ago, the 802.11n standard turned the WLAN world on its ear. Topics like antenna diversity and single channels gave way to Multiple Input Multiple Output (MIMO) antennas, a slew of new modulation types and channel bonding. Now 802.11ac promises to push the wireless realm into the gigabit era.
But 11ac isn't the only news from the front lines of the war for faster wireless. Researchers at MIT caught the attention of the media and the wireless-minded thanks to a recently discovered scheme that uses mathamatic equations to reduce the number of inevitable retransmissions on the wireless network, called Coded TCP.
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If it lives up to its promise (a big if in these early days), this upstart technology is just as compelling for what it doesn't do as it is for its expected benefits. By not requiring any more spectrum or output power, Coded TCP immediately becomes interesting to a world of wireless admins who need to worry about both spectrum and signal strength. What's the lure of Coded TCP? By employing simple algebra-based changes to the way packets are sent, the receiving device can compute what data is missing when loss occurs, rather than asking for a retransmit. And the payoff evidently is quite large.
Test scenarios by the researchers developing Coded TCP, led by Muriel Medard, an MIT professor, have yielded startling increases in performance. A 500-Kbps connection before Coded TCP became 13.5-Mbps by using the new method. A 1-Mbps experience became 16-Mbps. Evidently the industry is taking note. An MIT/Caltech startup company called Code-On Technologies has reportedly licensed its magic to several companies, although the list isn't public information yet. The techniques used in Coded TCP can also potentially be applied to 3G and 4G networks.
The wireless industry has come a long way by harnessing the power of new techniques and technologies to make WLANs robust and effective, and the interest in 802.11ac is a prime example. If a development like Coded TCP bears fruit, we'll have some pretty exciting days ahead of us, as well.