How to lower the latency in my RM126x P2P network in Europe?

Answer

The RM126x P2P mode implements LoRaWAN standards to broadcast packet between peers over long distance. This approach allows regulatory certification achieved for the LoRaWAN modes of operation of the RM126x to be applied to the P2P mode. It means that customers can develop their P2P application without fearing to be be outside of any regulatory enforcements. 

In Europe the limiting factor for latency will be duty cycle enforcement of 1%. The minimum latency time to broadcast messages within a P2P network will be mainly a function of the Window Length, which is the time between two consecutives beacon generated by Device 0. As Window Length increases, it increases the latency to send messages. In other words : The longer the Window Length and the longer your devices will be waiting for sending a message.

The Window Length will be impacted by following parameters :

1) Network Size

2) Packet Size

3) Data rate (Message and Beacon)

The right configuration for a given application will always be a trade-off but in order to transfer packets more often, you'll need to :

1) Limit the number of device within a P2P network (up to 64 max).

2) Reduce the Time On Air (TOA) by sending shorter message packets. 

3) Make sure that Beacon and Message Data Rates match and both use the lower possible value.

More information can be found into Application Note - P2P User Guide - RM126x Series.