The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost bandw

viewfly · Sep 30, 2013

From MIT Technology Reviews today.

http://www.technologyreview.com/new...ily-all&utm_medium=email&utm_content=20130930

How Apple Could Boost Speeds 20 Times on the Next iPhone

The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri. Further tweaks could boost bandwidth 20-fold in some cases.

By David Talbot on September 30, 2013

WHY IT MATTERS

By one estimate, global mobile data traffic will increase 13-fold between 2012 and 2017, requiring new solutions for adding capacity.

A wireless networking technology found in Apple’s new operating system could—if tweaked—provide a 10- to 20-fold bandwidth increase in some situations, like on a moving train or in a busy urban environment, new research suggests.

The technology is called multipath TCP. It allows you to use multiple wireless networks—such as 4G and Wi-Fi—at the same time. But Apple isn’t using it fully, nor is it using an advanced version—one that also encodes the data being transmitted in new ways— recently shown to provide those dramatic potential gains.

The advance, based on work done by a multi-university group led by Muriel Medard, an electrical engineering professor at MIT, is “very compelling” and “shows dramatic improvement in terms of increased data rates, reduced latency, and reduced packet loss,” says Andrea Goldsmith, professor of electrical engineering at Stanford and a leading network researcher and entrepreneur not involved in the work.

Right now, as any smartphone owner knows, a phone or tablet will either use Wi-Fi or 4G or 3G—and never at the same time. So your streaming video may cut out because the network you were using dropped, even though there’s another signal available.

Multipath TCP could change this by divvying up those video bits across two or more networks. “Multipath” refers to using more than one wireless route, and TCP refers to the protocols used by most Internet traffic. Then, to use a simplified explanation—all “odd” packets (units of data that make up an Internet transmission) get sent over Wi-Fi and “even” ones over 4G. Then these “odd” and “even” packets get woven back, zipper-like, on the phone.

But in practice, it’s not that simple. The problems start with the fact that data-transmission takes longer from a cell tower than it does from a Wi-Fi router. Throw satellite streams in and the transmission delays are even longer.

Multipath TCP makes up for this by tweaking transmission speeds. But matters get more complicated if you are moving around, meaning those timings are always changing—and worse still, if some packets drop out. When those things happen, the computation required for multipath processing can get so complex that it actually slows down the overall speeds, says Medard.

And that may be why Apple—in using multipath TCP only for its voice-query engine, Siri—apparently isn’t even using both cellular and Wi-Fi networks at the same time. Rather, it may be using the technology to simply enable Siri to switch back and forth between them without user intervention, so it can avoid having to retransmit your spoken request, a source of delays.

“The rumors I’ve heard is that Apple is using it for Siri just to decrease latency by using whatever network connection is available,” says Jason Cloud, a grad student in Medard’s lab.

Trudy Miller, an Apple spokeswoman, declined to comment on how the technology has been deployed. (Apple has been characteristically secretive about the technology; so one of the first hints that it was using multipath at all came when a Belgian researcher, Olivier Bonaventure, blogged about it earlier this month.) Several groups around the world are working on the technology.

At any rate, there is a technology that helps solve the remaining problems with multipath TCP. It is called “network coding”—an extra tweak atop multipath TCP. Network coding algorithmically combines packets in elegant ways. Then multiple packets can be turned into a single number that’s a function of the ones making it up. “You code within flows for redundancy,” Medard says. “Then you don’t have to be managing between them like crazy.”

It was this version that, when tested by Cloud and colleagues at the Hamilton Institute, part of the National University of Ireland in Maynooth, Ireland, provided up to 10 times better performance on a single network path, by repairing dropped packets on a single connection. This expanded on work Medard did last year (see “A Bandwidth Breakthrough”).

Measurements done at the University of California, Los Angeles, suggested how network coding could turbocharge multipath TCP. In findings presented in June, Medard and several university collaborators measured actual packet losses and other conditions around a Westwood, California, campus from three wireless sources: Wi-Fi transmitters, cellular towers, and Iridium satellites. They concluded the technology could provide a similar benefit when used on multiple paths, with a potential tenfold increase per path.

Demonstrations are planned over the next year. But commercialization of the underlying network coding technology is already possible. Medard says several organizations have licensed the technology from an MIT-Caltech startup called Code-On Technologies. She says she can’t name the companies.

Goldsmith says that while she didn’t know the details of what Apple has done, “it’s great to see Apple move in this direction, as it will inspire more developments in theory and practice.”

While “it is a no-brainer” to move forward with industry adoption of network coding with multipath TCP, implementation will likely have to start with applications where the data can easily be coded and decoded at either end—like, say, on a video application. “It’s very difficult to fundamentally change the network. There are a lot of entrenched players and entrenched technology,” Goldsmith says.
Click to expand...

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Steve B · Oct 10, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

Am I reading this right? Apple only uses it for SIRI? Has this been proven? I was hoping this would solve the problem with iPhone on the fringes of a WiFi hotspot where it constantly hangs on to a unusable WiFi signal and doesn't revert to a cellular connection.

viewfly · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

According to the article no one knows for certain. And the article is about the 5S.

It is also about simultaneous use, not switch off as in the example you give.

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RadioRaiders · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

Interesting. Seems to be coming out of the Linux camp?

In July 2013, the MPTCP working group reported four independent implementations of Multipath TCP, including the reference implementation in the Linux kernel.

The currently available implementations are:

Linux Kernel (reference implementation) from Université Catholique de Louvain. [4]
FreeBSD (IPv4 only) from Swinburne University of Technology. [8]
Citrix Netscaler. [9]
Apple iOS7, released on September 18, 2013 is the first large scale commercial deployment of Multipath TCP. [10]
Multipath Networks is implementing a crowd-sourced router through indiegogo. [11]
Click to expand...

Some implementations on the Samsung S4 and 2:
MultiPath TCP - Linux Kernel implementation : Users - Android browse

I imagine it will be included stock on upcoming Android versions. Everyone loves to keep their spec-sheets in-line almost as much as they luvs teh benchmark testing

Steve B · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

viewfly said: ↑

According to the article no one knows for certain. And the article is about the 5S.

It is also about simultaneous use, not switch off as in the example you give.

Sent from my iPhone 5 using Tapatalk Pro
Click to expand...

I need to update my profile. LOL. I do have the 5S. The reason why this thread caught my eye was because the iPhones do love to hang on to unusable WiFi. I saw this multipath TCP as the answer. In fact, where I originally saw these "feature" at, they talked about my specific issue. So I'm hoping Apple isn't just limiting this to SIRI.

viewfly · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

RadioRaiders said: ↑

Interesting. Seems to be coming out of the Linux camp?

Some implementations on the Samsung S4 and 2:
MultiPath TCP - Linux Kernel implementation : Users - Android browse

I imagine it will be included stock on upcoming Android versions. Everyone loves to keep their spec-sheets in-line almost as much as they luvs teh benchmark testing
Click to expand...

It doesn't seem to be coming from the Linux camp. Rather suggested TCP extensions from the IETF, a voluntary group promoting internet standards, without any real power.

I'm guessing that Apple is doing their own proprietary experimentation with MCTCP, as are the others mentioned.

Apple's iOS 7 is the first large-scale use of a newly-minted Internet protocol, called multipath TCP. It lets computers send and receive data across different network paths and interfaces at the same time, such as Ethernet, Wi-Fi and 3G.

The new protocol has been in the works for several years, and became an “experimental standard” of the IETF in January, as RFC 6824. Six months later, three implementations had been developed, including one for the Linux kernel. The Linux implementation is a project of the IP Networking Lab, part of the department of computing science and engineering at the Université Catholique de Louvain in Louvain-la-Neuve, Belgium.

This week, completely unheralded, Apple’s iOS 7 became the first big commercial release of MPTCP. HERE
Click to expand...

Original Blog that discovered the feature in iOS

On September 18th, 2013, Apple releases iOS7 which includes the first large scale commercial deployment of Multipath TCP. Given the marketing buzz around new iOS7 releases, when can expect tens of millions of users who will use a Multipath TCP enabled device.

Packet traces collected on an iPad running iOS7 reveal that it uses Multipath TCP to reach some destinations that seem to be directly controlled by Apple. You won’t see Multipath TCP for regular TCP connections from applications like Safari, but if you use SIRI, you might see that the connection with one of the apple servers uses Multipath TCP.
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And the IETF (internet engineering task force) memo on MCTCP extensions.

Given the experimental nature of it, and the lack of control that Google has with Android with each cell manufacturer, it will probably get screwed up in Android.

RadioRaiders · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

viewfly said: ↑

It doesn't seem to be coming from the Linux camp. Rather suggested TCP extensions from the IETF, a voluntary group promoting internet standards, without any real power.
Click to expand...

The reference model is built on Linux, so it's coming from that direction.
Multipath TCP

viewfly said: ↑

it will probably get screwed up in Android.
Click to expand...

I'm sure Apple is the only one who can get anything right

dmapr · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

RadioRaiders said: ↑

I'm sure Apple is the only one who can get anything right
Click to expand...

Even Apple can't get everything right. However, when something doesn't get done right in iOS, everybody knows who's to blame: Apple. When something gets screwed up in Android, nobody knows who's to blame. Kernel guys? Google? Manufacturers that tweak Android? Carriers that tweak the tweaked Android?

viewfly · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

It's interesting that this feature gets little press. Being that Apple is the first mobile platform to give it a try, on a scale of 200 million or so, it's seems more innovative and useful implementation then say going from a 4 to 4.3 inch screen.

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dmapr · Oct 11, 2013

Re: The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boost b

viewfly said: ↑

It's interesting that this feature gets little press. Being that Apple is the first mobile platform to give it a try, on a scale of 200 million or so, it's seems more innovative and useful implementation then say going from a 4 to 4.3 inch screen.
Click to expand...

I think that's because this feature is actually aiming at being invisible to the user. Unless you're actually watching closely you may not even notice minute transitions. For example, in the building where I work I often go Wi-Fi-mobile-Wi-Fi as I move between floors. Unless my eyes are glued to the screen I won't notice the Wi-Fi was dropped for 5-6 seconds it took to switch between base stations. 4" vs. 4.3" screen is something everything can see immediately and most people can relate to in one way or another.

viewfly · Oct 12, 2013

The new iPhone breaks ground by seamlessly sharing Wi-Fi and 4G for Siri; boo...

dmapr said: ↑

I think that's because this feature is actually aiming at being invisible to the user. Unless you're actually watching closely you may not even notice minute transitions. For example, in the building where I work I often go Wi-Fi-mobile-Wi-Fi as I move between floors. Unless my eyes are glued to the screen I won't notice the Wi-Fi was dropped for 5-6 seconds it took to switch between base stations. 4" vs. 4.3" screen is something everything can see immediately and most people can relate to in one way or another.
Click to expand...

Yes I agree and appreciate that point. It's these unseen engineering changes that make the overall experience better. As is the faster response touchscreen.

And most of that is missed by even expert members of forums like these. Not much one can do with a slab of glass and metal- but changes inside can be huge.

Another example. The 15% pixel area increase is huge for camera performance, even though the number of pixels hasn't changed. Most just count pixels. Same with the dual, 2 temperature LEDS. That's a real first for any camera. Back on the screen: 15%. That's like going from a 4 to 4,6 inch screen to place it in perspective.

It's these under the surface changes that intrigue me on any platform.

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