The CDMA reverse channel is fundamentally different from the forward channel. It employs OQPSK rather than QPSK used in the forward  channel. OQPSK is closer to a constant envelop modulation. This constant modulation technique provide for a more power efficient implementation of the transmitter at the MS. The QPSK modulation is easier for demodulation again at MS. The overall structure of the reverse channels in IS-95 is shown below:

Compared with the forward channel, there is no spreading of the data symbols using orthogonal codes. Instead, the orthogonal codes are used for waveform encoding. This means that the reverse link employs an orthogonal modulation scheme that consumes bandwidth but reduces the error rate performance of the system.