I’m interested in doing diversity switching between two wifi dongles connected to my companion computer. I see that the RFD900 Radio Modem does diversity switching using two antennas. Is this based of noise? signal strenth? RSSI? Please help clarify so I could implement using wifi dongles connected to two usb ports on a RPi.
Your best bet is to send an email to the manufacturer - RFDesign and ask them the question.
Thanks, Grant.
You probably want to implement diversity on the radio side, not on the network adapter side. Because each wifi dongle will have a different MAC address, you’d need to dynamically change routing along with switching the wifi adapters, which would probably be excessively complex, needing either a mesh networking protocol or another handshaking protocol between nodes.
I’ve used the Alfa networks adapters on projects similar to yours with success. Here’s an 802.11n adapter with diversity.
https://www.alfa.com.tw/products_show.php?pc=67&ps=230
If you did want to use two adapters, I’d do away with monitoring signal quality at all and just use a mesh network (I’ve used batman). Then the traffic would automatically choose the best adapter arrangement based on which was successfully receiving each network packet (#1, #2, or both).
The method used is like this:
- when receiving the preamble signal strength on both antennas is measured
- the antenna with the higher signal strength in the preamble is then used to receive the packet
- on send, the antenna that was used for the last receive is used to send the packet