In CDMA cellular system, it is important to reduce intersymbol interference in order to increase channel capacity. CDMA using orthogonal spreading code has been applied in forward link, but it is difficult to be applied in reverse link because of the intersymbol interference when it is not in a synchronous state. In this paper, we propose an orthogonal CDMA without synchronization that does not cause intersymbol interference in the asynchronous state, and we evaluate the validity of proposed system by computer simulation. As a result, conventional CDMA and orthogonal CDMA with synchronization cause some degradation of the bit error rate characteristic in forward link, and cause degradation of the bit error rate characteristic remarkably in reverse link without transmitted power control. The proposed system in forward link and reverse link without transmitted power control, however, has the same bit error rate characteristic as that of one channel.
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