ABSTRACT
Since all three of these eects change with time or position, they cannot be known at the time that the system is designed. us, if no form of adaptation is performed while the system is operating, the system must be designed to in some sense deal with the worst case, which can be very expensive in terms of system resources. For example, if all users in a cellular system have to assume worst-case path loss and shadowing (e.g., behind a large building at the very edge of the cell) regardless of their location, they will transmit at maximum power, thus maximizing battery usage and the interference to other users. erefore, wireless system adaptation has been a topic of critical interest in recent years.
