Context aware communication systems are the communication systems that allow automatic adaptation of devices, systems, and applications to the changing user's context. The context is the information characterizing the situation of an entity and providing information about the present status of people, places, things and devices in the environment. An entity is a person, device, place, or object relevant to the interaction between a user and an application, such as location, time, activities, and services. Context awareness allows for customization or creation of the application to match the preferences of the individual user, based on current context such as enterprise environment or home network.
Context awarenes is the general additional understanding required by gadgets in a communication system to convert data into meaningful information. When two gadgets are communicating with each other, sending each other data, the sending device’s context and the recieving device’s context hence the need for each one to reinterprete or modify the message as it goes up or down the chain.
Even your mobile gadget is designed in way that it should be aware of it's context in order to save resources like battery.
More can be found on these articles
http://www.springer.com/gp/book/9783319590349
Conference Paper A comprehensive framework for context-aware communication services