Sending Data In Bursts of SMS Messages

An anonymous reader writes "Canadian carrier Rogers has been experiencing some extreme loads of late, as researchers at the University of Waterloo investigate the potential for sending data spread across bursts of hundreds of text messages. They sent around 80,000 messages in the course of a project testing a new protocol able to cram 32KB into 250 messages sent from a BlackBerry, reaching a rate of 20 bytes per second. The group thinks its protocol could be useful in rural areas of the developing world where text messaging is the only affordable, reliable link."

Comments

Oops

[ekgringo]

Make sure you get the "unlimited" text messaging plan before trying this...

Re:Oops

[TheRaven64]

It's completely idiotic. There are two ways in which SMS is implemented:

On older GSM networks, it's part of the control channel. There is some unused space in one of the control packets. It was a scarce resource and flooding it could actually prevent anyone making calls (there was a fairly simple DoS attack possible). This was the original reason for SMS being expensive - the network couldn't handle much SMS traffic.

On newer networks (GPRS and newer), it's just treated as data. It's wrapped in a packet header indicating that it's SMS and then sent in the same way as IP data.

In any area where you just have GSM, there isn't enough bandwidth available for SMS for this to be useful. In an area where you have GPRS or anything newer then SMS is just a way of adding a huge packet header to your IP packets. It's transmitted the same way as IP data, you're just using the available bandwidth less efficiently.

Re:Oops

[newcastlejon]

...In any area where you just have GSM, there isn't enough bandwidth available for SMS for this to be useful.

In these circumstances CSD is probably available too at a heady (in comparison) 9.6kbps.

My 300 baud modem shivered...

[Overzeetop]

...and got to feel the thrill of competition again.

Re:My 300 baud modem shivered...

[Anonymous Coward]

So the clear answer is voice-over-ip-over-sms

Re:My 300 baud modem shivered...

[bill_mcgonigle]

I remember using acoustical modems back in 1974 and they weren't that new back then

I've actually considered seeing if I could get a v.32 in-software stack to communicate over the bluetooth headset/microphone protocol so I could do very basic data networking over a cell phone without a data plan. Like ssh.

I came to my senses, but I kinda still want to try it anyway.

Re:My 300 baud modem shivered...

[tepples]

The lossy compression used in digital cellular telephony has a smearing effect that screws with the rapid phase transitions used by quadrature amplitude modulation. You aren't going to get a lot of bits per second out of digital voice.

Big money, no wammies

[Itninja]

In a completely unrelated story, the University of Waterloo has an unexpected ~$16,000 shortfall this quarter.

How truely AWFUL...

[nweaver]

Text messages are one of the most awful forms of data on the cell network. On a 3G type network, they are just data, so hey, if you can do TXT on 3G, just do data. So what?

But on older networks, such as the proposed usage, they take up CONTROL channel space, and too much SMS is a DOS attack!

See Exploiting Open Functionality in SMS-Capable Cellular Networks:

ABSTRACT: Cellular networks are a critical component of the economic and social infrastructures in which we live. In addition to voice services, these networks deliver alphanumeric text messages to the vast majority of wireless subscribers. To encourage the expansion of this new service, telecommunications companies offer connections between their networks and the Internet. The ramifications of such connections, however, have not been fully recognized. In this paper, we evaluate the security impact of the SMS interface on the availability of the cellular phone network. Specifically, we demonstrate the ability to deny voice service to cities the size of Washington D.C. and Manhattan with little more than a cable modem. Moreover, attacks targeting the entire United States are feasible with resources available to medium-sized zombie networks. This analysis begins with an exploration of the structure of cellular networks. We then characterize network behavior and explore a number of reconnaissance techniques aimed at effectively targeting attacks on these systems. We conclude by discussing countermeasures that mitigate or eliminate the threats introduced by these attacks.

Calling smart people

[Applekid]

Anyone care to describe why they couldn't just use airtime minutes and an acoustically coupled modem? Looking it up on Wiki, in general they were able to transfer 300 bps instead of 160.

Re:Unusable and expensive

[schon]

You pay: Monthly for a cellular package with unlimited texting
You get: 20 baud

Actually, (ignoring the fact that "baud" is the incorrect term) that would be either 160 or 200 baud, depending on whether you include error correction bits in the calculation. :)

Wrong solution

[maxrate]

Not trying to troll, but this is the wrong 'solution' for so many reasons. If SMS's can make the connection, so can other forms of packet radio.

Re:Why bother?

[EricJ2190]

If it's anything else, drive to Starbucks for free wifi.

Because Starbucks is so commonplace in the "rural areas of the developing world."

This is Tailor-Made for...

[srmalloy]

... next year's April 1 RFC -- "IP over SMS Carrier".

Re:Why??.....

[GNUALMAFUERTE]

I think this is more a case of "Look mama, IP over SMS! With No hands!" than a solution for any real world problem.

Re:so now will they bill $1 per txt each way?

[geekpowa]

In emerging economies SMS is dirt cheap. In Philippines: $0.50, 24 hour all you can eat (on-net only) deals are common.

This is a bad idea for a large number of technical reasons : very inefficient use of the GSM channel because of all of the excessive handshaking and control just to transmit a 140 byte data packet for one (sms is 7bit per character. 160 chars = 140bytes) and rubbish throughput & latency. But economically it makes sense. Also accessibility of 2G mobile phones is very high in such environments, 3G wireless or twisted pair copper not so much. Depends where you deploy it, for what eventual purpose and actual real bandwidth requirements.

Neato!

[zmollusc]

This is good news (everyone), by the time you have torrented your bluray rip, it will be out of copyright.
Or not.

Yak Protocol

[Ukab the Great]

Maximum carrying load of a Yak: 70kg
Weight of a 32GB micro sd card. 0.5g
Having your own 3rd world petabit network: priceless.

What do you mean?

[colinnwn]

I have to pay $10 when I text "HAITI" to 90999! I thought Microsoft was paying.

Re:so now will they bill $1 per txt each way?

[fuzzyfuzzyfungus]

It's an especially terrible plan, if widely adopted, because SMS comes out of the control channel. If you have enough SMS traffic flying around, the carrier will either have to start dropping it, or have plenty of available voice/data channel lying idle because they don't have enough control channel capacity to set up and tear down calls.

Obviously the poor people in the sticks might not have fancy 3G stuff; but why would you attempt to shove data over SMS(aside from short message snippets from embedded devices, and suchlike applications), when GPRS already exists? All sorts of dirt cheap phones support being used as modems, without any special software, and, while it might well be more expensive now, for economically perverse reasons, SMS won't be cheaper for long if it becomes standard practice to do general-purpose data transfer over SMS on a large scale...

Re:so now will they bill $1 per txt each way?

[Peach Rings]

Maybe they should just make normal data transfer reasonably priced instead of jacking up SMS pricing...