| 摘要 |
PROBLEM TO BE SOLVED: To provide a voice quality as high as possible in a CDMA digital cellular system. SOLUTION: When a vehicle telephone exchange 15 determines through an entire system traffic monitor means 27 of a traffic statistical program 18 of the exchange 15 (step S1) that a high traffic state occurs with few remaining radio capacity of an entire CDMA system a subscriber having a high personal base traffic is selected from a subscriber database, and also when the subscriber is using a 13K voice CODEC, the exchange 15 in this system forcedly sends to a radio base station controller 14 and corresponding cellular subscriber terminals 1 and 7 an instruction to switch to a 8K voice CODEC or an enhanced 8K voice CODEC only during a high traffic time, and increases the system radio capacity by the above switching operation. When the situation returns to a normal traffic level, the 13K voice CODEC that has a high voice quality is returned. |
