Time division multiple access divides time into periodic frames, and each frame is divided into several time slots to send signals to the base station. In the case of timing and synchronization, the base station can receive the signals of each mobile terminal in each time slot without mutual interference. At the same time, the signals sent by the base station to a plurality of mobile terminals are sent in sequence within a predetermined time slot. As long as each mobile terminal receives them in the designated time slot, it can distinguish the signals addressed to it from the combined signals and receive them. Compared with FDMA, TDMA has the advantages of high communication slogan quality, good confidentiality, large system capacity, etc. However, accurate timing and synchronization are necessary to ensure the normal communication between mobile terminals and base stations, which is technically complicated.