Our current requirement (ideally I should add) is to use beacons as in this example.
We have a device which we build the beacons into, for example an order for a coffee. The customer takes this unit and finds somewhere to sit down. This maybe anywhere within the building or maybe outside.
When the customer find somebody, the beacon is then stationary and we and identify where they are for a quick delivery of their item when ready, This data would then be fed back to a system which would identify, maybe on a screen where that customer would be.
My misguided idealism is that with the long battery life available within the beacons, we could use one set of beacons which as normal indoor tracking would be stationary and fixed around the location and an additional beacon built within the device to be passed to the customer.
Though yes, we have looked at and successfully built systems with both Raspberry Pi 3 as the collector (the fixed beacon locations) and as Raspberry Pi 3 as the item being tracked, they give us two issues that are not suitable for using in a scale able business product.
1). They need power. Yes they can be run from battery packs, but even with the Pi Zeros, the power consumption is too high. Building in a rechargeable system into the units and the back end for that makes the product cost prohibitive.
2). They are fragile. There are too many things that can “just go wrong” and with hundreds if not thousands of these being deployed, the ongoing maintenance is not something that I would want to manage. Again the cost of providing that would make the end result cost prohibitive.
There are plenty of similar systems already on the market, using both RF and WiFi connectivity, but BLE with it’s stability, portability and long individual battery life makes it a very compelling product to use.
There are new devices coming onto the market all the time, with the new generation of BLE beacons being able to run code directly on them, allowing for the ability to create mesh networks and conversations between devices which would create this very outcome. The market for BLE is not just for those who have a phone in their pocket.
Look through your own forums and you will see there are plenty of posts from others looking for the reverse scenario of what you’re creating and something that some of the other early adopters of BLE have already seen and are bring products to the market this year.