A method for mobile communication and a system thereof are provided. The system for mobile communication includes a main base station and a plurality of sub-communication devices. The sub-communication device is one of a sub-base station and a user equipment. The sub-base stations and the user equipments are located in the macrocell of the main base station. The method includes the following steps. First, locations of the sub-communication devices are obtained. Then, the sub-communication devices are grouped based on the locations of the sub-communication devices. And, an allocation of resource blocks is obtained according to the grouping results. The sub-communication devices receive the allocation of resource blocks for control signaling and data transmission. And, the usage of same resource blocks are enabled by the sub-base station allocated in the same resource blocks in response to receipt of the allocation.