Requirement for a mesh network using Zigbee or similar technology

Question

I have a requirement to design a proprietary monitoring system. (There's some intellectual property involved so I'll describe the system with a slightly altered purpose.) Imagine a large factory floor with dozens of devices scattered about (devices stay in one fixed location) and we want to be signaled when a device loses power. Every device has a free USB outlet. The concept is to design a dongle that plugs into each USB outlet, and simply draws the 5V, ignoring the data lines. The 5V powers a wireless chip like perhaps an XBEE device. Every device has an ID. The devices form an ad hoc network. A base station device then periodically interrogates the network (using e.g. a python api) to see if all the devices are there. If not, the missing devices are noted and an alert is generated.

The benefits I see are:

• No receivers have to be scattered around the facility since this is a mesh network.
• Low cost
• Propagation likely better than WiFi and this uses a simpler connect/disconnect protocol

My questions are:

• Is this possible with XBee or another widely available, inexpensive device?
• Are my assumptions correct?

I'd prefer to only get feedback from people that have real-world experience with mesh networks. I've already done a lot of research and know what is promised by various approaches, I'm now looking for real experience from people.

Thanks!

Answer 1

https://www.instructables.com/id/XBee-Mesh-Network-Construction/

XBee seems to support mesh networks almost out of the box.

https://circuitdigest.com/microcontroller-projects/raspberry-pi-xbee-module-interfacing#:~:text=So%2C%20before%20using%20the%20XBee,the%20laptop%20using%20USB%20cable.

Interfacing with a Raspberry Pi or similar computer system may be useful for your purpose.

https://xbplib.readthedocs.io/en/latest/#:~:text=The%20XBee%20Python%20Library%20is,an%20easy%20and%20smooth%20process.

You may also want to use Python to script your particular application. This sounds similar to a sensor network.

Answer 2

The only problem with a mesh network is that unless you have a dense enough network that there are multiple paths to every node, then if you loose the wrong node you can end up getting an alert suggesting that power has failed to half the monitored devices.

A work around would be to have a small battery on the USB device so that it can be charged by the host device and it can then send a message when the power is cut, rather than polling the network to see which devices are missing.