Orthogonal Variable Spreading Factor Codes Suppressing Signal-Envelope Fluctuation

摘要

Recently, complex orthogonal variable spreading factor(OVSF) codes based on polyphase orthogonal codes have been proposedto support multi-user/multi-rate data transmission services in synchronousdirect-sequence code-division multiple access (DS-CDMA) systems. Thisstudy investigates the low signal-envelope fluctuation property of the complexOVSF codes in terms of transmission signal trajectories. In addition, anew method is proposed to suppress the envelope fluctuation more stronglyat the expense of reducing the number of spreading sequences of the codes.