Apple's use of multipath TCP is only the beginning

Multipath TCP, currently being used by Apple (NASDAQ:AAPL) in iOS 7 to combine cellular and Wi-Fi for use by its voice-query Siri technology, could be tweaked to provide a 10- to 20-fold bandwidth increase, according to researchers in a multi-university group.

Apple is reportedly using the multipath TCP (MPTCP) protocol only to enable Siri to switch back and forth between cellular and Wi-Fi as needed, rather than combining the channels for greater bandwidth. That could be tacit acknowledgement that MPTCP can be a real pain to implement.

In certain use cases, the computations required for multipath processing can get so complex that overall speeds slow. But by adding network coding to MPTCP to algorithmically combine multiple data packets together for transmission, actual packet losses can be dramatically decreased, according to MIT Technology Review.

A version of this approach was built upon work done by Muriel Medard, an electrical engineering professor at the Massachusetts Institute of Technology (MIT), and tested at the Hamilton Institute, part of the National University of Ireland. "It provided up to 10 times better performance on a single network path, by repairing dropped packets on a single connection," said the Technology Review.

Medard and collaborators also conducted tests of encoded MPTCP at the University of California, Los Angeles (UCLA). In a presentation this past June, they reported that the technology could deliver similar benefits on multiple paths to create a potential 10-fold increase per path.

Several organizations have already licensed the encoding technology from an MIT-Caltech startup called Code On Technologies, according to Medard, who declined to name the licensees.

Meanwhile, an Irish startup called Multipath Networks is working to commercialize MPTCP. The company claims it can combine up to four connections--including wireless, DSL and cable--at once to create one fat pipe that can deliver data speeds up to 100 Mbps. Its channel-bonding service relies upon an off-the-shelf Linux router and cloud-based service.

The company launched an Indiegogo crowdfunding campaign last week, aiming to raise $30,000. The company has promised that if more than 50 people from any locality sign for any pledge level, it will install an aggregating server for its service as close as it can to that location.

Despite MPTCP's promise, some are casting a wary eye regarding the likelihood of the technology's widespread commercialization.

The Register spoke with Geoff Huston, Asia Pacific Network Information Centre (APNIC) chief scientist, and came up with three significant hurdles that will hold back ubiquitous MPTCP. For one thing, the use of MPTCP could confuse a lot of handshake-sensitive middleware, breaking the various layers of middleware that exist between a servers and the outside world. Further, if carelessly implemented MPTCP could result in handsets consuming expensive cellular data rather than Wi-Fi data. Finally, if MPTCP begins to pose a serious threat to carrier business models, they will find a way to put an end to it.

For more:
- see this MIT Technology Review article  
- see this Multipath Networks release and Indiegogo web page
- see this Ars Technica article
- see this Register article

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