Using a standard protocol can sometimes be challenging in terms on integration and especially when an application has hard real time or power requirements. For those situations a custom RF protocol can be more appropriate.
Simple Mesh is a small library that creates a mesh network with a thin layer on top of the Nordic Shockburst direct messaging protocol which is itself the first layer controlling the Radio peripheral registers
Currently a Zephyr port is ongoing to cover a large support nRF51, nRF52, …
This framework has achieved ultra low power with minimal wakeup time radio communication
This framework is well adapted to be a backend for nRF5x devices acting as host of UWB transceivers, it provides an addition communication channel independent from UWB that can be used for commands and configuration