| 摘要 |
A mobile communication system including a base station, a first user terminal and a second user terminal that establish a connection with the base station, and a core network that accommodates the base station, supports cellular communication in which a data path set between the first user terminal and the second user terminal passes through the core network and D2D communication in which the data path does not pass through the core network. The D2D communication includes a first D2D communication mode in which the data path does not pass through the base station and a second D2D communication mode in which the data path passes through the base station. When a communication state of the D2D communication in the first D2D communication mode has been deteriorated, the first user terminal and the second user terminal make a transition to the second D2D communication mode to transmit non-transmitted data and then switch the D2D communication to the cellular communication. |
