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Various digital modulation techniques have been extensively studied and have found numerous applications in wireless communication systems. One example of this success is the QPSK modulation used in the third generation Universal Mobile Telecommunication System (UMTS). This paper presents a new modulation method that produces less adjacent channel interference (ACI) and lower bit error rate (BER) than the QPSK modulation with linear amplification. We call this new modulation technique Soft Orthogonal Phase shift Keying (SOPK). This modulation is perfect for a new coding method OVSF-MAC that can at least duplicate the binary throughput in the UMTS down link channel.