Highly recommend this to anyone starting out with lorawan/ttn - its gets deeper and deeper but certainly the first half should be at hand to those playing/working in this area 
Modeling the Energy Performance of LoRaWAN
I stumbled across this document whist looking at power consumption on boards (Lorawan and power performance go hand in hand I guess), also just had a bench power supply upgrade 
this allows me to do things I could neve do before.
Hope its not been shared before, if so sorry.