RE: BLE mesh LPN localization questions / suggestions

tesc — Mon, 11 Apr 2022 12:48:17 GMT

Hi,

Our recommendation for new projects is to use nRF Connect SDK (i.e. the new SDK which is based on Zephyr OS.) This is where new development and new features will happen, whereas the nRF5 SDK is now in maintenance mode and will only receive security patches and other bugfixes.

Regarding LPNs, they can only receive messages via the Friend, and they also send messages to the Friend in order to poll for new messages. However, when they send messages on the mesh network, they use the same approach as any other node on the network. This means any protocol relying on the node sending messages, will work exactly the same as for any non-LPN node. It is only messages being received by the LPN that are different (as they always come from the Friend.)

Please note that RSSI is not an accurate measurement of distance. The measure is simply an indication of the power level received around the given channel, and the accuracy may vary depending on the surroundings. There will be situations where the signal strength is weaker due to loss of line-of-sight (e.g. people in the way,) or because the signal received is reflected off a surface (e.g. wall, ceiling.) You can get multi-path issues with constructive and destructive interference (direct signal mixes with signal bouncing off one or several surfaces.) You can get interference from other RF sources, and you will experience other effects such as antennas not sending and receiving uniformly (all antennas have better gain in some directions than in others.)

Regards,
Terje