Methods and apparatus, including computer program products, are provided for power optimization. In one aspect there is provided a method. The method may include receiving, at a user equipment, configuration information including an active time wherein the active time is less than an allowed clock drift of a clock at the user equipment; and receiving, at the user equipment, data sent in advance by an application server, wherein the advance comprises a time based on at least the allowed clock drift. Related apparatus, systems, methods, and articles are also described.