Ajay,
Enabling ADR on both sides should be all you need to do.
See the ADR section on the page below:
http://www.multitech.net/developer/software/lora/introduction-to-lora/
The gateway must RX enough packets to get a good sample before it will request the end device make any changes to TX datarate or power.
You can find more info about ADR in the LoRaWan specification.
Cheers,
Mike