To improve line utilization efficiency in short-cycle data collection, it is provided a method of managing communication in a communication system, the communication system including: an aggregation unit configured to receive information through a communication path from a plurality of terminals, which are sources of information transmission; and a reservation unit configured to determine, for each of the plurality of terminals, timing at which the terminal transmits a signal, the method comprising steps of: receiving, by the reservation unit, a relative time specified by a user as a time at which the terminal transmits the information; and determining, by the reservation unit, as scheduling information, an absolute time unique throughout the communication system so that interference with another communication session is avoided when the terminal holds communication at the relative time.