The simplicity of these is that its a transparent UART channel so you can add as many transceivers as you like and all the nodes will get the data. You need to create some kind of simple model based on JSON, where you embed an ID, the NODE you are interested in a multi tenant environment, and the command or data. JSON is easy to read, compressed well when theres loads of its better than XML, or any other custom models.
{nodeid: ABC123, temp: 12, humid: 15, wind_speed: 0, wind_direction: 25, etc ...
These are fairly cheap and have built in stacks to modulate demodulate the data. With all
2.4Gigahertz
For quite a while these were pretty expensive to produce but recently it looks like the market got flooded with an IC that can be made cheap and easy. This 2.4Ghz module can receive and send, on selected channels, which do not interfere with WiFi because of isolation.
These can be found for about £1.40 on eBay. The only drawback is that it is not easy to tune the signal strength but it is much more stable than sub giga when in range.
SUB Gigahertz
Cheap and loads of them out there. Some countries allow you to amplify signal to cover miles and miles of directional wireless connections.
You can get 433mhz serial links found under 433mhz Arduino Radio or similar. Make sure to get TRANSCEIVERS, as some are just receivers or transmitters.
This is a more directional transceiver - Better range in a straight line but works omnidirectional too. The obvious drawback it needs some more space for the antenna
There are also ones with an embedded coil. They work well too. I can't comment on min or max ranges but we are talking about 10-30metres, maybe more.
You can use even cheaper transmitter if bought in bulk on devices like sensors, where they just send data every 12 hours, or on a trigger, etc. And use only 1 receiver, because all the data is on a single 433mhz channel. Beware that other devices, not yours might be transmitting on these channels too, car remotes, garage doors, heat meters, etc..
The drawback is security is virtually non existent and to secure secret data, you should not use any of these modules on this page.
In my opinion, these are the simplest and cheapest way to do it.
