System , comprising - a communication station for communicating with a number of radio tags (7 - 14) using a time slot communication procedure, in which a number of time slots (Z1 - ZN) per time slot cycle in a repeating sequence are available for communication and each time slot (Z1 - ZN) is characterized by a unique time slot symbol (ZS1 - ZSN), wherein the communication station is designed to emit a synchronization data signal (SD) at the beginning of the respective time slot (Z1 - ZN), comprising the time slot symbol (ZS1 - ZSN) for the time slot (Z1 - ZN) currently present, and wherein - a radio tag (7 - 14) is designed: + to switch from a standby state (S) into an active state (E) at a wakeup time (TA1), and + to receive the synchronization data signal (SD) in the active state (E), and, + if the received time slot symbol (ZS1 - ZSN) indicates a time slot (Z1 - ZN) destined for it, to define a new wakeup time (TA2) corresponding to the next occurrence of the time slot (Z1 - ZN) destined for it in a time slot cycle that follows the currently present time slot cycle, and wherein - the communication station is designed to embed address data (AD) in the synchronization data signal (SD), by means of which a number of radio tags (7 - 14) per time slot (Z1 - ZN), which is destined for said radio tags (7 - 14), can be individually addressed, and - the radio tag (7 - 14) is designed, if the received time slot symbol (ZS1 - ZSN) indicates a time slot (Z1 - ZN) destined for it, to evaluate the synchronization data signal (SD) with regard to the address data (AD) contained and to check whether it is individually addressed. - a communication station for communicating with a number of radio tags (7 - 14) using a time slot communication procedure, in which a number of time slots (Z1 - ZN) per time slot cycle in a repeating sequence are available for communication and each time slot (Z1 - ZN) is characterized by a unique time slot symbol (ZS1 - ZSN), wherein the communication station is designed to emit a synchronization data signal (SD) at the beginning of the respective time slot (Z1 - ZN), comprising the time slot symbol (ZS1 - ZSN) for the time slot (Z1 - ZN) currently present, and wherein - a radio tag (7 - 14) is designed: + to switch from a standby state (S) into an active state (E) at a wakeup time (TA1), and + to receive the synchronization data signal (SD) in the active state (E), and, + if the received time slot symbol (ZS1 - ZSN) indicates a time slot (Z1 - ZN) destined for it, to define a new wakeup time (TA2) corresponding to the next occurrence of the time slot (Z1 - ZN) destined for it in a time slot cycle that follows the currently present time slot cycle, and wherein + to switch from a standby state (S) into an active state (E) at a wakeup time (TA1), and + to receive the synchronization data signal (SD) in the active state (E), and, + if the received time slot symbol (ZS1 - ZSN) indicates a time slot (Z1 - ZN) destined for it, to define a new wakeup time (TA2) corresponding to the next occurrence of the time slot (Z1 - ZN) destined for it in a time slot cycle that follows the currently present time slot cycle, and wherein - the communication station is designed to embed address data (AD) in the synchronization data signal (SD), by means of which a number of radio tags (7 - 14) per time slot (Z1 - ZN), which is destined for said radio tags (7 - 14), can be individually addressed, and - the radio tag (7 - 14) is designed, if the received time slot symbol (ZS1 - ZSN) indicates a time slot (Z1 - ZN) destined for it, to evaluate the synchronization data signal (SD) with regard to the address data (AD) contained and to check whether it is individually addressed. <EOS>