Which protocol to use?

[Pavel K]

Hi everyone,

We are trying to choose which protocol use for connecting devices based on Nordic SoCs. We use devices in following way:

1. about 300 - 500 devices (wearable - smart watches)
2. industrial site, walls, concrete, metal etc.
3. site area up to 1 km2
4. each devices send data to gateway - 6 kbytes every 10-20 minutes and 190 kbytes 3 times a day
5. protocol should support identification of sent data (from which device it arrived)

I know it is a lot to ask, but what would you suggest?

Regards Pavel

[endnode]

You cannot cover the area without heaving easy access to (ideally) multiple "boarder" exit points at the time. Yes, it can work as demo or in theory with large network of moving devices and just few exit nodes but our research (~2 years ago) showed that even the best in class (at that moment) commercial mash networks based on 2.4GHz radio cannot achieve any reasonable throughput in anything like real time (like dozens of seconds or minutes between event on the device and information reaching backend/boarder). And that was just ten devices in few rooms. I cannot imagine how that could reliably work with hundreds of devices on area of square kilometer. But maybe BT SIG mash or some other proprietary/open source project can deliver better performance today then what I've seen some time ago. And yes, battery operation definitely don't help, you can end up with battery life in weeks.

[endnode]

I could imagine that with having hundreds of moving battery powered devices and roughly the same number of grid powered stationary observers connected to some high-speed network like WiFi or Ethernet. Taht will work pretty well even with BLE on such large area even if it is construction hall in car factory or similar thing (after some fine-tuning of course to cover all special shielded corners). But installation, maintenance and purchasing cost of such system will be significant (basically 5-10$ per moving beacon + 10-100$ per boarder observer, 10-100 of units replaced per year, 2-6 weeks of full time installation job of 2-10 people - basically engineers who understand deeply the radio and whole system - also replacing of batteries basically once a month to all moving units + probably 12 full-time guys to maintain the system and device fleet). Still it can be great but...

[endnode]

...you need to be damn sure what to do with the data to justify such investment (big industrial manufacturer investing in IoT should go there, others probably not).