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Increasing Wireless Network Speed By 1000% By Replacing Packets With Algebra
MrSeb writes "A team of researchers from MIT, Caltech, Harvard, and other universities in Europe, have devised a way of boosting the performance of wireless networks by up to 10 times — without increasing transmission power, adding more base stations, or using more wireless spectrum. The researchers' creation, coded TCP, is a novel way of transmitting data so that lost packets don't result in higher latency or re-sent data. With coded TCP, blocks of packets are clumped together and then transformed into algebraic equations (PDF) that describe the packets. If part of the message is lost, the receiver can solve the equation to derive the missing data. The process of solving the equations is simple and linear, meaning it doesn't require much processing on behalf of the router/smartphone/laptop. In testing, the coded TCP resulted in some dramatic improvements. MIT found that campus WiFi (2% packet loss) jumped from 1Mbps to 16Mbps. On a fast-moving train (5% packet loss), the connection speed jumped from 0.5Mbps to 13.5Mbps. Moving forward, coded TCP is expected to have huge repercussions on the performance of LTE and WiFi networks — and the technology has already been commercially licensed to several hardware makers."
...I don't see how it will solve "spectrum crunch" when every nibble of your LTE bandwidth is oversubscribed by 5 to 1. Whether you have 32 users doing 10 Mbps streams, or 320 user doing 1 Mbps streams, it's all accounted for. I'd certainly like to be one of the 10, but 20 Mhz worth of spectrum at 16 symbols/Hertz is not a limitation you can change with fast/excellent forward error correction.
If you've ever used Usenet, and you've used parity files to recover missing segments of data, then you know exactly how this technique works.
Frankly, I'm surprised it took so long for someone to apply it to lossy network environments. It seems obvious in hindsight.
Cyde Weys Musings - Scrutinizing the inscrutable
I agree that it's not a magic bullet. The point is, however, that the overall throughput of the network was increased by better usage of the available resources! If the *effective* available bandwidth is increased, then the performance of everyone "nibbling" on that network will *also* presumably increase. Also, think how much more money carriers may be able to squeeze out of users without needing to invest more in infrastructure! [/sarcasm]
Article is very light in details (except "Libraries of Congress" things), but it looks like those guys implemented a kind of error correction code (ECC) to recover lost data through extra data found in other packets. This has been in use for various types of networks (optical, DSL, GSM) for years.
Of course it is all down to how good the actual algorithm ("algebra") is in terms of overhead vs extent/capability of error correction vs introduced coding delay. There is always a trade-off, but a particular algorithm can take into account technology specifics (WiFi) and optimize it very well for a given task (whole packet lost, but not so often).
Journalists like to put BIG BUZZWORDS to well known things.
It's an error-correction method that happens to have compression built-in.
Also, I really wish people would stop shitting on new technologies like they're some sort of oracle. This is awesome. Accept it.
It's better to vote for what you want and not get it than to vote for what you don't want and get it.
- E. Debs
Shannon Limit shows that there is only so much information that can fit in a channel.
Plenty of forward error correction codes exist (algebraic encodings) to enable a channel to approach the shannon limit. Most of you have heard of Reed-Solomon or Hamming Code before.
NASA has used these since the 1970s to provide a more robust link with the effect of utilizing more bandwidth of that link.
This is a little fancier than what I mentioned, but conceptually similar I imagine. The advantage of just using some existing forward error correction, perhaps combined with one of the popular compression algorithms, is that techniques that have been in use for the past 4 decades probably can't have enforceable patents placed on it.
“Common sense is not so common.” — Voltaire
Also, think how much more money carriers may be able to squeeze out of users without needing to invest more in infrastructure!
This might actually hurt them then because they charge by what was transmitted, not by what was received.
Don't know something? Look it up. Still don't know? Then ask.
Actually they came up with yet another method of Forward Error Correction (FEC). I haven't had time to read the article and look forward to see how they compare to Reed-Solomon or other Reed-Muller codes (Walsh-Hadamard code is used in CDMA).
This isn't exactly new but I'm glad to see someone take the initiative to apply it to today's WiFi networks. The mentality as of late is that the speed is more than fast enough to deliver the data and the occasional resend. FEC currently used where data rates are quite limited or the latencies are such that retransmissions are prohibitive long.
These comments are my own and do not necessarily reflect the views or opinions of my employer or colleagues...
Think of it as bitmap vs vector graphic.
I drank what? -- Socrates
It doesn't necessarily need support from the server hosting the content. Any router along the path could take the old-style packets and wrap them in new-style packets. Since the servers are likely to be using wired connections anyway, this technique might not help them a lot anyway; the real win is using this to beef up the connection from the radio tower (be it cell or wifi) to the client (be it cellphone or wireless card), and that's a much smaller set of hardware/firmware to update.
Car analogy: Somebody ships you a car. It arrives with a bent bumper. Instead of having the source shipping you a new car, you just unbend the bumper.
Sadly, most people who are plumbers are probably better qualified then most people who call themselves programmers. I think that all degrees/diplomas should require some kind of apprenticeship/co-operative education/internship program to get you real on the job experience. There's only so much that can be learned in the classroom. Being on the job, doing actual work allows you to learn a lot of stuff that just would not come up in a classroom.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.