| 摘要 |
In the construction of a mobile communications system wherein coder-decoder units for high-efficiency coding which should originally be placed in base stations are arranged in a concentrated manner in a mobile exchange office, a circuit changing-over switch is provided as a part of the communications circuits extending from the base stations to the mobile exchange office and the coder-decoder units in the same office. Consequently, the total number of coder-decoder units is reduced to a number which is smaller than the total number of base stations and which corresponds to the volume of traffic of the entire system. Further, when a communication channel is prepared at the time of a call origination or hand-over, since the setting of a communication channel is completed after synchronization is established between a base station and a coder-decoder unit, interruptions of the service are prevented at an initial stage of setting of a communication channel.
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