Provided are a mobile communication system, method and device, which relate to the technical field of communications. The system comprises: an anchor node, a master node, a relay network and a terminal, wherein the anchor node is connected to the master node by means of a fixed connection, and the anchor node is an anchor point of a user plane and/or a control plane; the master node is connected to the relay network by means of a first wireless connection, and the relay network is connected to the terminal by means of a second wireless connection; and the relay network comprises at least one relay node, and in the at least one relay node, there is a first relay node directly connected to the master node, and there is a second relay node directly connected to the terminal. Provided is relay technology suitable for a 5G system, which implements route transmission and multi-hop transmission from a relay node to a master node.