Comparison of attractive modulation schemes for the uplink in DS-CDMA systems

Several modulation schemes combined with convolutional coding which are attractive for the uplink in DS-CDMA systems are compared based on the criterion of maximum power efficiency. It is shown for typical system assumptions that 2PSK either with pilot channel or with pilot symbols time-multiplexed with data symbols, and 64-ary orthogonal modulation combined with coherent demodulation lead to the highest power efficiency. If the receiver complexity is taken into account, the conclusion is that 2PSK is the most suitable modulation scheme for the uplink in typical DS-CDMA systems.