PROBLEM TO BE SOLVED: To provide an orthogonal complex spreading method and its system for a multiplex channel by which a problem of unbalanced power between in-phase channels and orthogonal phase channels is solved and which has an advantage over complex spreading systems proposed by CDMA-ONE in the U.S. and by W-CDMA in Japan and Europe from the standpoint of power efficiency.

SOLUTION: Orthogonal complex spread miodulation is called an OCQPSK (orthogonal complex QPSK). Data for a multiplex channel and subject to gain and orthogonal Hadamard sequence for each channel two channel data multiplied with the gain and the orthogonal Hadamard sequence are summed in a complex form a complex multiplier applies complex multiplication to the value summed in the complex form and the outer orthogonal Hadamard sequence in a complex form and provides outputs of in-phase information and orthogonal phase information. The in- phase information outputted from lots of blocks is summed to the in-phase information and the orthogonal phase information is summed to the orthogonal phase information and the result is spread by using a spread code in the orthogonal complex spread method for the multiplex channel.

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