# Use of RFID or suitable alternative to remotely communicate change in system state

I have a physical system which is dispersed over about 20-30 metres cubed and at random points within this space there are electronic nodes which have single binary outputs.

I want to monitor every time any of these outputs goes high from a central location accepting occational losses. The essential criteria in the solution is that each node communicates wirelessly and utilises the minimum amount of power possible.

My question:

• 1) Is there a way to leverage (hack) RFID technology for this purpose, perhaps powering an active RFID tag for a transmission and reading this transmission from the central location?
• 2) If this is not possible, what would be the most common solution in such a scenario where power is highly constrained and fault tolerance (acknowledgement / confirmation) is important but not paramount? Would Bluetooth LE be my best bet or a different solution?

• How will the active tag know when to wake up? At the end of the day you can buy a transmit module for about $4 and a micro for about$1. You are then in control of the design rather than trying to hack something you are not in control of. – Andy aka May 7 '15 at 9:35