PURPOSE: To make a guard time unnecessary to improve the efficiency of line use by constituting a TDMA communication system so that a carrier frequency is different between adjacent time slots.

CONSTITUTION: In this example, each time slot has not a guard time. If a receiver is placed near a transmitter, the receiver receives a superposed transmission radio waves of each transmitter in a time zone Tp. In this example, carrier frequencies f11 and f12 of transmitters 11 and 12 are made different from each other. If the receiver selects a time slot 1 and receivers radio waves having the carrier frequency f11 from the transmitter, a switch S1 selects a band-pass filter 33, and a switch S2 selects a local oscillator 37. A mixer 36 generates an intermediate frequency fif=g11-fL, and an intermediate frequency amplifier 39 amplifies this intermediate frequency fif.