July 23, 2008 – Alex Leonov, Director of Marketing Communications of Moscow-based MeshNetics, shares why wireless sensor networks solve challenges for building management.

MeshNetics has announced a new product in the 900 MHz range for ZigBee. Tell us why people should pay attention to that.

LEONOV: ZigBee is a great technology. It is the first standard for wireless sensor networks and has been doing great over the last few years. The majority of the ZigBee solutions to date were based on 2.4 GHz band, which is a worldwide band and has definite advantages; but ZigBee is also designed to have another frequency band, which is sub GHz.

Now, 2.4 GHz, there is a lot going on in that band, isn’t that correct? Does ZigBee have any issues with being the 2.4 band?

LEONOV: It is a license-free band and yes, it is used by other technologies, such as Wi-Fi and Bluetooth. So far, ZigBee has been doing remarkably well. The ZigBee software includes so-called “frequency agility” that allows it to switch channels if they become crowded. But, still, the challenge remains because the band is used by other technologists as well.

How does that change by moving to 900 MHz?

LEONOV: Well, 900 MHz is not a replacement for 2.4 GHz, it is a complementary band. It is important for use regionally and in certain applications. Unlike 2.4, it is not worldwide. It is 915 MHz in the U.S. and 868 MHz in Europe.

Would there ever be a time where a customer might use both 2.4 and 900 at the same time?

LEONOV: It is a possibility, although right now I can't name any examples of that. But that is probably because we just introduced the 900 MHz product. In the future, we may see some sort of combination of those bands in the market.

The new 900 MHz module is completely pin compatible to our 2.4 GHz module; that is important to know.

If someone buys your development kit for 900 MHz, what type of applications are they typically thinking about?

LEONOV: If you think modules are something that may work for you, you buy a kit. You have development boards, which have all kinds of connectors, have built-in sensors, and they are based on the module. You can test the module in different modes and in your particular environment.

Wait a minute. What do you attach the module to? You’re not using it in free space. What sort of thing would you be using it with?

LEONOV: Not only is the module used with sensors for the majority of applications, it is a kind of wireless sensor network. Right now major application areas include HVAC control, safety monitoring. There are other applications as well, which fall into the general information area.

Building automation is a great example; let's dig into that. Is it typically done in new building or retrofit?

LEONOV: Both. Running cable is real expensive. I read once that it is more than hundred dollars per foot, which is doable. And there are some areas of building where it is physically next to impossible to run the cable. So, wireless is a clear alternative.

The only challenge is that wireless normally needs to be battery operated. So the battery life would be the limiting factor. ZigBee, as a standard, was introduced to address this precise challenge. It is very low power application, which is more than sufficient for the majority of sensor products and allows a long battery life.

So, for an HVAC application, is the module attached to the switches dictating the control of the system, in terms of when it is on or off? That sort of thing?

LEONOV: That also. You can have sensors; you can have actuators; or you can have both on the same device. You can monitor sensor data for temperature, humidity; and then the command can be sent wirelessly to switch on or off the lights or air conditioning. Often it doesn’t require any human intervention.

Who is attaching, so to speak, the sensors to the network? Is that something you are providing your customers with or must they then take the development kit and do that?

LEONOV: Our customers are mostly OEMs and system integrators, so they design their own products. What we do, we help “ZigBee enable” them. We provide building blocks for ZigBee networks.

You can think of the modules as wireless networking cards, like the one you add to your computer and, boom, you get the wireless capability. Same thing with modules. It is almost as easy to do.

I know you also offer software. How does the software relate to the modules? Does it control the modules in some way, help manage the modules?

LEONOV: Yes. We call it ZigBee Stack software. It is embedded into a microprocessor inside the module. It allows you to control the module, or control other applications through the module.

You can also think of a module as a wireless modem, which you can send commands to an operator.

It sounds like, based on the kind of customers you have, they are able to modify the software they get from you.

LEONOV: Yes. We have two options. For those customers who don’t want to get into these complications, we offer so-called AT commands, which allow you to operate the module as a modem. But, we also provide the full API for the ZigBee Stack, which means a customer who has the expertise can customize their software.