The acquisition price of $18 million in cash by MEMSIC is not bad. For Crossbow is at least a success story when compared to some wireless motes companies, particularly those university spawned ones, that hoped to catch the WSN frenzy but folded along the way. Whether this is the exit strategy Crossbow had initially hoped for is hard to say. At least they found a buyer. But this deal also includes business lines which accounted for approximately $10 million in sales annually by Crossbow. Looks like the growth in demand for wireless sensor motes has not been quite as projected years ago. Anyway it is probably best for the Crossbow that the manufacturing, sales and marketing side of the business be in the hands of MEMSIC, who is better at it, while they concentrate on where they initially did best, higher up in the value chain. Make no bones about it, wireless motes will ultimately become low cost commodities. It is going to be tough to keep two conflicting business ambitions running at the same time for any small company. So it is a good move for Crossbow afterall.

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As far as I am aware, off-the-shelf batteries are not designed for long lifetime use, in the order of years. Yet they are being used for long term deployment in WSN. I’ve seen theoretical projections of how long low power wireless motes can last. But there still seems to be an unknown quantity on the profiles of batteries, when used for a long time by wireless motes, drawing µA current…

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Having not been keeping in touch with news about WSN for 3 weeks while I was on holiday, I’m notified by my colleague today that SunSPOTs are now finally available in the EU area. But checking on their website myself, it seems that it costs much more to get a Sun SPOT development kit in Europe than in the US after currency conversion (€627 compared to $550 excluding tax), which is probably not news anymore given the fact that it’s almost always more expensive to buy goods in Europe than in the US. However Europeans can probably take heart from the news that they are soon going to change the pricing in the US from $550 to $750 (apparently as of 27th Feb 2008) Well, perhaps not, €627 is still a lot of money. Just shows that wireless sensor motes are still very much in the prototype stage.

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ZigBee modules are readily available nowadays. Assuming that they can all live up to their expectations, providing the network stack that allows wirelss sensor motes to be easily organised into a network fit for deployment, we will be seeing a host of software applications to be developed for wireless sensor networks this year. My concerns with ZigBee are, forget about large-scale or maybe even medium-scale sensors deployment, the ease of deployment of a ZigBee wireless sensor network and the lifetime of the network. Remember, there were a lot of hypes around multiple hops wireless ad hoc networks not that long ago when the concept was first put into trial. Don’t get me wrong, the potential of such networks is still there. But, under the constraints of current underlying technologies, the deployment of these networks for the applications initially expected of them is not as simple as the name of these networks would have you believed. Work is currently still on-going in this area, so I won’t be surprised if the ZigBee stack is still someway away from being ready for some serious applications. What I’m more interested in is better tools to diagnose a wireless sensor network as at the moment troubleshooting a network of these little motes when something goes wrong is still painfully difficult.

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There was a short article in the October IET magazine about using a small ZigBee sensor the size of a hearing aid to collect and transmit data from the human body. I suspect that hearing-aid-size sensor, which is “inspired by the semicircular canals of the inner ear responsible for controlling motion and balance”, is probably only made up of a simple accelerometer sensor, which can be easily found in most prototype wireless sensor motes on offer in the market nowadays. Nothing earth-shattering really, in my opinion, merely decoupling a simple sensor from wires. If the “whole package” is just about monitoring raw data collected from the sensor then that is even more disappointing. The power of modern sensor network lies in its ability to gather information from multiple cheap wireless sensors, with the resultant information giving more accurate insight into the sensed object or enviroment than a single sensor can achieve. I’d expect more from the “pioneer” in body sensor networks!

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