Internet of Things

Internet of Things
by Paul McLellan on 11-01-2012 at 8:10 pm

 Another announcement from the Warren East’s ARM keynote this morning was the creation of a SIG within Weightless, which is an organization responsible for delivering royalty-free open standards to enable the Internet of Things (IoT). The SIG is focused on accelerating the adoption of Weightless as a wireless wide area global standard for machine to machine short to medium range communication. The founder companies are ARM, Cable and Wireless Worldwide, CSR (formerly Cambridge Silicon Radio) and Neul.

As Warren pointed out in his keynote, if you are very local there are a number of good standards such as WiFi and Bluetooth that you can use for wireless connectivity. If you are outside and want to go over 100m, say, then pretty much you have to use cellular technology such as GSM, CDMA or LTE. The trouble with that is that it is optimized for human communication such as voice or surfing the net and as a result it is very time and power intensive and the batteries don’t last long (think months).

Weightless operates in the whitespace being freed up as analog terrestial television gives back its spectrum. This turns out to be ideal for low power medium distance transmission for all the same reasons that back when TV was invented it was picked as the band: it transmits long distances at low power well, can go through wall, into basements and so on. Plus this spectrum is standard worldwide: although there are (mostly were) several different analog TV standards (NTSC, PAL, SECAM) the spectrum used for analog TV was internationally standard. This gives it a 4-10X gain in efficiency over the bands where cellular operates. The spectrum, as it frees up, is unlicensed and does not require complex antenna engineering.

For machine to machine communication, where latency is not a problem, the SoCs can sleep most of the time. Unlike cellular where you can’t wait 15 minutes for your phone call to connect (but you can wait a few seconds, I bet you didn’t know you already are doing), in applications like monitoring irrigation or power metering, this is not an issue. And the protocols can be optimized for this.

As an example of the mismatch between cellular standards, Gary Atkinson of ARM pointed out that for a smart power meter using GPRS (the data standard part of GSM) to transmit a single little bit of data (such as the current meter reading) takes 2000 packets. It is not a fair comparison, of course, but that is the point. GPRS is set up to assume you are going to want to send a lot of data in a timely manner and has a heavyweight protocol to make that happen.

The target is chipset cost under $2, range up to 10kM and a battery life of 10 years. A little different from the spec Apple is working on for the iPhone6.

The Weightless website.
Weightless wikipedia page.

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