To provide a mobile communication system for assigning related parameters of a parallel combination spread spectrum system to base stations so as to be adapted to respective margins of the number of spread codes and transmission powers by confirming a system resource (the number of spread codes) and a wireless resource (the transmission powers) which the base stations have.

A parameter decision section 202 adopting the assignment checks a parameter rate ROM 204 to extract parameter combination objects whereby a communication speed being a user warrant communication speed or over can be warranted. Then the parameter decision section 202 checks a parameter transmission power ratio ROM 205 to confirm the number k of spread codes and the transmission power ratio assigned to each object, then calculates the margin of the number of spread codes and the margin of the transmission power which the base stations have, then selects an adapted object on the basis of the number k of spread codes and the transmission power ratio assigned to each object by referencing the margins and transmits decided parameters to the base stations.