PURPOSE: To carry out a routing action in response to the traffic fluctuation by performing the dynamic switching of the selection patterns of bypass routes.

CONSTITUTION: When the final ground station is decided, this station is separated from other factors by an index 1. Then a TGX4 is selected as a counter station by an index 2 and branches as an index 3 by identification of the traffic distribution are adopted. If the in-traffic is increased from the counter station, a TRF1 is selected. Meanwhile a point P is decided again as a destination so that the routing is changed by an index 5 in a repeating traffic state. This procedure is repeated until the best route is selected. When a direct traffic state is set by the index 5, a route is decided to the final ground station TRX by an index 4. When a TRF0 is selected as an index 3, an out-circuit is started to the final route decided by the index 4.