http://www.sharetechnote.com/html/Handbook_LTE_DRX.html Even while there is no traffic between the network and UE, UE has to keep listening to Network. At least it should be ready to decode PDCCH. It means UE has to be "ON" all the time even when there is no traffic. But being ON all the time would drain the battery.You may ask "Then why don't UE shut down (getting into a sleep mode) when there ..