Abstract: A congestion control target call is selected so as to be capable of reducing inequality or the like between services or users in consideration of characteristics such as the urgency of the service or the user. A communication system includes a server device, a terminal device which transmits and receives a packet to and from the server device, and a communication device which relays communication of a packet with the terminal device and a control method thereof. The communication device selects a call which is a congestion control target on the basis of a value indicating a priority selected as a congestion control target and/or a bandwidth or a packet communication traffic volume occupied by a service or user when congestion occurs in consideration of characteristics such as the urgency of the service or the user when the congestion of the communication system is detected or foreseen.

Abstract: A mobile radio communication system having one or more relay stations and base stations, a gateway, an external device having a route selection function, and a policy control device which selects a main route and a sub route on the basis of residual resources in a radio communication device. The mobile station connected to one radio communication device can select another radio communication device having a large amount of residual resources as a new access point when the one radio communication device cannot be used, to prevent shortage of the radio resources. Also, it is possible to enable a process of selecting the radio communication device as a new access point to be omitted when switching one route to another by determining a sub route as the new access point when a main route is disconnected in advance, to shorten a service disconnection time.

Abstract: In a wireless communication system, when data communication is performed between a relay device and a terminal (in a second path), the same amount of data is required to be transferred between a base station and the relay device (in a third path). An amount of wireless communication resources required is obtained by adding an amount inversely proportional to a capacity of each of the second and third wireless transmission-paths. Therefore, the amount inversely proportional to the capacity of the third path is consumed in excess. Based on a channel quality of a first wireless channel between the base station and the terminal, a channel quality of a second wireless channel between the terminal and the relay station, and a channel quality of a third wireless channel between the base station and the relay station, it is determined whether data communication between the base station and the terminal is relayed.