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.

Related blog posts:

• ZigBee-compliant
• Wireless sensor that sits behind the ear
• Battery life for long term deployment

open-ZB is an open source implementation of the IEEE 802.15.4/ZigBee protocols. Apparently the website has been around for over a year, but not sure how long the implementation has been made available. It doesn’t seem like there’s a sizeable community using it, so if you are thinking of using the code, don’t expect to receive much support should you find out later on that the implementation does not work the way it should be. So far I’m yet to see any credible documents reporting on the use of this implementation, so it’s difficult to know how stable the protocol stack is. Perhaps it’s still early stage?

Related blog posts:

• ZigBee-compliant
• Wireless sensor that sits behind the ear
• How ready is ZigBee?

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!

Related blog posts:

• ZigBee-compliant
• How ready is ZigBee?
• Imagine

I remember doing a research on wireless sensor motes on offer in the market some months ago. It was incredibly difficult to find out exactly what does it mean when vendors claim that their motes are ZigBee-compliant. As usual from marketing materials, they do not tell you clearly the specs. Even datasheets mention nothing about ZigBee. It is one thing to be IEEE 802.15.4 compliant, but quite another if it is a ZigBee product. Anyway I have to look into the source code of the software that comes with these motes to figure out what exactly is implemented. To my surprise not only that there is not a ZigBee stack (well ZigBee is not supposed to be open source), the IEEE 802.15.4 MAC is not implemented. All there is is just the 802.15.4 PHY. No beacon mode for the supposedly more energy-efficient mode of operation in a star-topology, as is designed for in 802.15.4 standard. Very disappointing.

Anyway it’s good to see that some vendors stop using the term “ZigBee-compliant” to confuse people, when their products are not ZigBee, yet.

Related blog posts:

• Wireless sensor that sits behind the ear
• How ready is ZigBee?
• Open source ZigBee implementation