A communication device reads and stores in memory a state value which was utilized for operating a communication subsystem during a wake-up period of the communication subsystem. The device then causes the communication subsystem to enter into a sleep mode. Subsequently, the device causes the communication subsystem to exit from the sleep mode and enter into a current wake-up period. The stored state value is provided to the communication subsystem for use in operating the communication subsystem during a warm-up period of the current wake-up period. After the warm-up period of the current wake up period, a current state value is provided from a state controller to the communication subsystem for use in operating the communication subsystem during the wake up period. The current state value is determined based on a detected signal level of a current signal received in the communication subsystem.