Mobile communication system, transmission power control method therefore, and base station used therefore

A sum of transmission powers for all channels for transmissions from a base station (1 to 3) to mobile stations (8a to 8e) is controlled to constant. Specifically, the transmission power for a high speed and high capacity shared channel is controlled such that a sum of transmission powers for individual channels for individual mobile stations, and the shared channel is always constant. With this constitution, an interference wave power from neighboring cells becomes constant, an average data transfer rate of the shared channel becomes constant, a prediction precision for a wait time for sending/receiving data increases, a lower limit for an actual data transfer rate becomes high, and the number of users in a service quality assurance type service increases. Additionally, when the number of individual channels in use is low, the transmission power for shared channel can increase, and the transmission rate increases and the time decreases when a best effort type service is provided.