Wireless Sensor Networking Question

XBee & XBee Gateway XBee - Zigbee
1

Hi
I’ve just got a question regarding the wireless sensor networking of the drop in networking kit in this link:

http://www.digi.com/technology/drop-in-networking/wireless-sensor-networking.jsp

Where the mesh networking is used (as in the irrigation control, automated meter reading examples and onwards), why do the moisture and temperature sensors need to communicate with each other (mesh)? Why do we need a mesh network here instead of just using the star type network used for the ice skating rink example? For the mesh network, does this mean the Xbee module is also connected to a controller like a pc or something, so that it can send commands to nearby nodes in the mesh network?

I’m trying to create a drop in network using gas sensors and i’ve been given the drop in professional network kit, but i’m not too sure what type of network i should use. The project requires that it uses a mesh network but i dont know why or how. Why doesnt the irrigation control example (or the other examples using mesh network) use the star type network instead?

Hope someone can help me please. i’m sorry for the basic questions, i’m really new to this. thanks!

2

You are correct Meme, that the irrigation application could have used a start topology. This is of course, if all the sensors were in direct range of the collector. That however, is rarely the case in these kinds of applications. Because of obstacles, or if the sensors (and radios) are embedded into the ground, this can greaty affect the range of transmission of a wireless signal.

Meshing is simply used as a mitigating strategy to a possible problem in range. If necessary, the end devices may hop through other router devices to reach a single destination which is at an undetermined distance away.

While possibly not a necessity, meshing is often a strategy used to overcome range issues.