Code division multiple access mobile communication system

A method of transmitting a first signal from a mobile station to a base station, comprising the steps of:

• demodulating a radio frequency band signal received from said base station by use of a second signal from an oscillator;
• modulating the first signal to be transmitted by use of the second signal from the oscillator;
• and
• transmitting said modulated first signal,
• wherein an oscillation frequency of the oscillator is controlled by use of a change of phase shift detected using the demodulated radio frequency band signal received from the base station.

A mobile station which receives signals from a base station, comprising:

• an antenna for receiving said signals from said base station;
• an oscillator;
• a demodulator for demodulating said received signals using a signal from said oscillator,
• wherein an oscillation frequency of said oscillator is controlled by use of a change of phase shift detected using the demodulated signal received from the base station.

A mobile station for communicating with a base station, comprising:

• an antenna for receiving signals transmitted from said base station based on phase shift keying, and for transmitting signals to said base station;
• an oscillator;
• a demodulator for demodulating the received signals using a signal from said oscillator;
• a frequency correction circuit for controlling an oscillation frequency of the oscillator to correct frequency error based on a detected phase of the demodulated signal;
• and
• a phase correction circuit for correcting a phase of at least a part of the demodulated signals based on said detected phase of the demodulated signal.