Cellular mobile telephone communication systems refer to large and medium capacity mobile telephone communication systems that consist of several adjacent cellular (hexagonal) cell coverage areas to form a service area. The public land cellular mobile telephone communication system consists of a mobile service switching center, a base station (also known as a base station), a mobile station (also known as a mobile terminal, including handheld devices, portable stations, car mounted stations, etc.), and a transmission circuit, as shown in Figure 1. A mobile station consists of a set of devices and control devices with receiving and transmitting functions, which can automatically select channels for conversion and connection. The base station consists of receiving and transmitting equipment and control equipment. The receiving and sending equipment is used to establish communication connections between the base station and its mobile stations in the coverage area. The control equipment has various wireless management functions such as call keeping and channel conversion. The receiving and transmitting equipment and control equipment can be installed together in the same location or separately, with the base station located in the center of the honeycomb hexagonal community or at the top corner of the hexagon. The radius of the base station area is generally 1.5-15km. The core equipment of the mobile service switching center is a mobile phone switch, which functions to handle calls, roaming, wireless channel control, and achieve the connection between the wireless system and the local and long-distance networks. Each base station is connected to the switch of the mobile service switching center through wired or wireless relay circuits, and between the mobile service switching centers and between the mobile service switching center and the local and long-distance bureaus are also connected through relay circuits. In cellular mobile phone communication systems, repeaters can be established to receive and forward signals from base stations and mobile stations, in order to solve blind spots or dead spots in calls. Repeaters can also be used as an outward extension of the system coverage area
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