To compensate a changeover delay when a gateway station of a duplicated configuration is changed over.

A buffer time of a circulation buffer of a gateway station A10a which is an operation gateway station is defined as a time exceeding a changeover delay time required for changing the gateway stations, a buffer time of a circulation buffer of a gateway station B10b which is a gateway station for backup is defined as a time by subtracting the changeover delay time from the buffer time of the circulation buffer of the gateway A10a, and the gateway station B10b transmits data transmitted at fixed intervals from a service base 20 to a terminal 40 by maintaining the same transmission intervals as before changing the data even after changing the data.

COPYRIGHT: (C)2007,JPO&INPIT