A system is provided for generating a time reference in duty-cycled wireless communications. The system includes at least one master module including a master transceiver adapted to transmit data packets. The system further includes at least one slave module including a slave transceiver adapted to receive the data packets. The slave module further includes a signal generator adapted to generate a clock signal with a period equal to the time interval of two data packets transmitted by the master module. Moreover, the slave module further includes a slave timer adapted to utilize the clock signal as a time reference in order to perform the sleep/wakeup control for the slave module.