To provide a transmission apparatus and a communication system that transmit a plurality of transmission signals riding on different interfering transmission beams, separate and receive the transmission signal at the receiving side, and estimate the original transmission signal by maximum likelihood estimation based on the correlation among the received signals. A transmission apparatus which encodes the transmission signal by an encoding means to generate at least two transmission signals S1 and S2, modulates the signals to the carrier frequencies, weights them and supplies them to the antenna elements, and controls the weights to transmit the modulated output signals by beams partially overlapping each other in space. A reception apparatus which separates and receives the transmission signals by a channel adaptive antenna to receive at least two received signals RS1 and RS2 and estimates the original transmission signal using maximum likelihood estimation, for example, a Viterbi decoding algorithm, based on the correlation between the received signals so as to reduce the error rate of the received signal and realize an improvement of the quality of communication.