Abstract: A mobile terminal device for communication with other terminal devices via one of a plurality of base stations, at least one of the base stations using a radio access technology different from that of at least one other base station, the mobile terminal device includes: a capturing unit for capturing a radio communication signal transmitted from another mobile terminal device in proximity to the mobile terminal device to determine the radio access technology; a processor for controlling to communicate with one of the other terminal devices in accordance with a process including: determining priority of which of the radio access technologies; seeking one of the radio access technologies currently available in the order of the priority; setting up a radio communication condition using one of the radio access technologies; and initiating communication with one of the other terminal devices via said one of the base stations.

Abstract: A communication system includes a first base station for communicating complying with a first communication protocol, a second base station for communicating by using radio frames complying with a second communication protocol and transmitting synchronization signals complying with the first communication protocol, the synchronization signals synchronizing the transmitted radio frames, and a mobile terminal for communicating according to the process includes: receiving the synchronization signals from the second base station while communicating with the first base station, estimating transmitting timing of the radio frames including symbols on the basis of the received synchronization signals, measuring a receiving signal strength of the symbol on the basis of the estimated timing, and controlling a handover from the first base station to the second base station on the basis of the measurement result by the measurement of the receiving signal strength of the symbol.

Abstract: A communication system includes a first base station for communicating complying with a first communication protocol, a second base station for communicating by using radio frames complying with a second communication protocol and transmitting synchronization signals complying with the first communication protocol, the synchronization signals synchronizing the transmitted radio frames, and a mobile terminal for communicating according to the process includes: receiving the synchronization signals from the second base station while communicating with the first base station, estimating transmitting timing of the radio frames including symbols on the basis of the received synchronization signals, measuring a receiving signal strength of the symbol on the basis of the estimated timing, and controlling a handover from the first base station to the second base station on the basis of the measurement result by the measurement of the receiving signal strength of the symbol.

Abstract: A mobile terminal device for communication with other terminal devices via one of a plurality of base stations, at least one of the base stations using a radio access technology different from that of at least one other base station, the mobile terminal device includes: a capturing unit for capturing a radio communication signal transmitted from another mobile terminal device in proximity to the mobile terminal device to determine the radio access technology; a processor for controlling to communicate with one of the other terminal devices in accordance with a process including: determining priority of which of the radio access technologies; seeking one of the radio access technologies currently available in the order of the priority; setting up a radio communication condition using one of the radio access technologies; and initiating communication with one of the other terminal devices via said one of the base stations.

Abstract: A mobile communication system including a plurality of base stations includes a radio communicator for communicating with mobile terminal devices with a plurality of carriers, and a communication controller for changing radio field intensity of the radio communicator; and a management device including: a storage for storing information of each of the base stations, the information including time slots and a number of registration requests from the mobile terminal devices in each communication area of the base station in accordance with the time slots, and an instructor for instructing to change radio field intensity of the plurality of carriers to the radio communicator in the base stations on the bases of the stored information in the storage when the number of the registration requests in the time slot exceed a specified predetermined threshold value.