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ZigBee, would this Ad Hoc network idea work?

Former Member

 

I’m trying to get a general understanding for how a mesh Ad Hoc network could be created. ZigBee seems as a cheap solution so that’s why I’m going for it. However if you guys have a better suggestion (i.e. Bluetooth) feel free to suggest it.

 

Ok, here goes. My basic idea is this. I have moving objects (large area indoors) and I want to construct a simple warning system. When one device detects another I basically just want to play a tune or make a light flash, nothing more. The approach will probably be using RSSI but that is not important right now. I want this to be cheap and I do not want any kind of fixed infrastructure (disqualifying wifi). The devices would randomly come into contact, do some kind of handshake, talk while they are close and finally move out of range.


Is it even possible to create such a thing with ZigBee? The standard requires a ZigBee Coordinator so I was thinking that one moving object could be this and the rest ZigBee routers. Would this approach even work? Perhaps one could equip a few Raspberry Pi’s with “XBee ZB ZigBee RF Modules” and then take it from there.

 

 

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  • 0

    How many nodes would be the maximum?

    t seems you could use any low-cost radio with a small associated CPU for this application as long as collisions can be detected. It probably wouldn't need a big complicated ad-hoc protocol like Zigbee.

    • all nodes periodically broadcast their own ID - if a collision is detected, they re-transmit at a random time later
    • all nodes evaluate RSSI of all received broadcasts to determine who is close and how close
    • the periodic transmission time and the random re-transmission range of times are dictated by how fast the nodes can approach each other and how many nodes are active
    • if you have a lot of nodes, some careful statistical calculations will be needed to determine how many nodes can be handled before the congestion becomes a problem
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  • 0

    How many nodes would be the maximum?

    t seems you could use any low-cost radio with a small associated CPU for this application as long as collisions can be detected. It probably wouldn't need a big complicated ad-hoc protocol like Zigbee.

    • all nodes periodically broadcast their own ID - if a collision is detected, they re-transmit at a random time later
    • all nodes evaluate RSSI of all received broadcasts to determine who is close and how close
    • the periodic transmission time and the random re-transmission range of times are dictated by how fast the nodes can approach each other and how many nodes are active
    • if you have a lot of nodes, some careful statistical calculations will be needed to determine how many nodes can be handled before the congestion becomes a problem
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