A control device determines whether communications that a base station accommodates are congested, based on obtained information, and identifies a terminal that is accommodated in the base station in which it is determined that the communications are congested, as a terminal of which communications a proxy device is to control. The proxy device controls communications between the base station and a server, by using a protocol that acknowledges that the data has reached a reception side, calculates a loss rate in communications by the identified terminal are to be discarded, by utilizing acknowledgement packets which are used by the protocol, and relays a communication of the identified terminal, by a transmission band which has been reduced by the calculated loss rate portion.