  The LoRaWAN based Low Power Wide Area networks aim to provide long-range
connectivity to a large number of devices by exploiting limited radio
resources. The Adaptive Data Rate (ADR) mechanism controls the assignment of
these resources to individual end-devices by a runtime adaptation of their
communication parameters when the quality of links inevitably changes over
time. This paper provides a detailed performance analysis of the ADR technique
presented in the recently released LoRaWAN Specifications (v1.1). We show that
the ADR technique lacks the agility to adapt to the changing link conditions,
requiring a number of hours to days to converge to a reliable and
energy-efficient communication state. As a vital step towards improving this
situation, we then change different control knobs or parameters in the ADR
technique to observe their effects on the convergence time.
