low power establishment

[jowei]

Hi Nordic

I am using mesh sdk4.1 LPN example to develop a LPN product, we seems found that LPN's RF range will degrade large compared to common mesh node.

We want to try tuning some mesh stack parameters to improve RF range.

We focus on Friend establish procedure first, 

So In spec 3.6.6.4.1, "After 100 milliseconds have passed from the Friend Request the node should listen for up to 1 second for the Friend Offer messages sent by potential Friend nodes......."

For mesh sdk4.1, how to modify the 1 second of "listen for up to 1 second"?

Thank you

[Mttrinh]

Hi,

Friend offer scanning time(1 second) is set via public API(look at "mesh_lpn_friend_request" descripstion). 100 milliseconds are hardcoded in definition "MESH_LPN_FRIEND_REQUEST_TIMEOUT_MIN_MS". It is possible to change both of these values. However, it might break this:

If no acceptable Friend Offer message is received, the node may send a new Friend Request
message. The time interval between two consecutive Friend Request messages shall be
greater than 1.1 seconds.

That might not be acceptable for some Friend implementations.

Just be aware that the 1 second is possible to change and we provide the ability to do this. The 100ms is also possible but you need to understand what and how.

[Mttrinh]

Hi,

The MESH_FRIENDSHIP_RSSI_FACTOR is the weight factor applied to the received RSSI by the Friend node. Available factors are 1.0, 1.5, 2.0, and 2.5. The lower the factor, the less a low received RSSI increases the delay of the Friend Offer. MESH_FRIENDSHIP_RSSI_FACTOR_2_0 just means that the weight factor is 2.