Best pratice solution for designing a 50 nodes system cover 100 meter range.

[Hust]

Hello DevZone team, 

Currently, I want to design a wireless sensor system which can cover around 100 meter range.

It can be in any kind of topology: mesh, star, ... as long as it meets the requirements: retrieve data from 50 other sensor nodes with speed is around 1kByte per second.

As far as I know, nrf52840 long range still not available for mesh network design: https://devzone.nordicsemi.com/f/nordic-q-a/37952/mesh-networks-on-nrf52840-dongle and if we use normal connection, it can not meets the requirements: 50 nodes. 

Any suggestion on this?

Thank you very much.

[Joakim Jakobsen]

Hi.

Sounds like Mesh would be a good solution for you.

As far as I know, nrf52840 long range still not available for mesh network design

You are correct. The Mesh Specification is based on the Bluetooth 4.2 specification, so there is no BT5 features available. 

In order to solve challenge with the range, you can add relay nodes between the sensor node and it's destination.
That way you can cover larger distances in your network.

The relay nodes will scan for messages from your sensors, and relay them through the network.

Best regards.

[Hust]

the thing is I want it to be real-time, and the speed is strict to at least 1 kByte per second, Im just affraid that the mesh and relaying will cause the delay.. 

[Joakim Jakobsen]

I understand.
Adding relay nodes will of course add some delay, but in my opinion it might be the best way to solve this.
It is of course up to you how much delay is acceptable.

Even if you are using BLE and the Long Range feature, you aren't guaranteed 100 meters of range. This will heavily depend on the physical layout of the area, interference etc.
If you want to use BLE, you are also limited by the maximum of 20 concurrent connections.

You could look at a solution where your sensors is simply broadcasting their data.
This way you can make use of the BT5 features and you are not limited by the 20 concurrent connections.

Regards,
Joakim.

[Hust]

Thank you very much for your time, 

I get it now.

Best regards,

Dat.