mass deployment of sensors

[Luke_123]

Hi,

Just wondering how to configure the BLE for an example use case given below:

A factory where there are 500 temperature sensors installed. What is the right approach/configuration/way to get the data from all these temperature sensors ? How to design a system for this use case, can this be achieved using BLE ?

[Edvin]

I was about to write something, but then I saw Torje already replied something, and I agree with what he says. The answer to your questions depends on a lot of factors, besides the number of temperature sensors. I will add another cent to Torje's reply:

What distances are we looking at? Are all 500 nodes within radio range of a single gateway node? If so, it would be possible to do some sort of beacon sensors, that would just advertise it's temperature data, and the gateway can just scan for advertisements, and forward the data. If they are not within range, you have a few options:

You can use several gateway/scanner nodes, to cover the entire area. Another option is to use Bluetooth Mesh, which is a short range network, where all the nodes will act as relay nodes, extending the range of the network. Whether or not this is possible with 500 nodes depends on the sample rate. Ideally, Bluetooth Mesh is not ideal for a lot of throughput, and since Bluetooth Mesh is a flooding mesh network, every node will repeat all messages it can hear (a very simplified explanation). So this works great for one node reporting to many nodes (e.g. light switch telling all the light bulbs to turn on the light), but it doesn't work as well if all nodes report their own sensor data, like in your case. It heavily depends on the report rate. Also, Mesh nodes draw quite a lot of data, since they have to have the radio turned on in RX mode at all times. 

The same applies for BLE beacons and scanners. How often the devices advertise will set the limit (not a hard limit, but the performance decreases) for how many nodes one scanner can pick up. You can use this tool (online power profiler) to see how much time one advertisement uses on air. Then you have a bit of processing time on the scanner as well. Depending on the advertising interval you can caluclate how many advertising nodes it takes to fill 100% of the time. Then, since they are not synced, you should subtract some, in order to give it some slack. 

Another option is to do this in a BLE connection, but that limits the number of nodes every gateway can handle quite a lot. 

At least, this is something for you to consider as a starting point. Perhaps you can share some more details on your needs, and we can discuss further if you like. Please note that we are closing in on the holiday season, so please expect longer respond times. We will be back to normal capacity in January.

Best regards,

Edvin

[Luke_123]

Thank you Edvin  and Torje  for your replies.