“You could use the wireless M-Bus protocol which supports hundreds of nodes pr concentrator. How often do you need to transmit from each sensor?
I would advice on 433MHz which will give you better range with same output power. The 433MHz requires a longer antenna, but usually 433MHz is no problem to make a good antenna even with limited space. 169MHz is more difficult as you write.
Are the sensors battery operated?? Then a mesh protocol is limited value, unless you can use repeaters?
The wireless M-Bus protocol includes a repeater, which should extend the range for the sensors with the longest range.
Last Update: October 10, 2017