A low-complexity multitone-CDMA communication technique

Digital implementation of multitone (MT-) CDMA systems often involves considerable complexity. Assuming the spreading-sequence length, N, is a multiple of the number of subcarriers, M, this paper proposes a new digital technique that achieves low-implementation complexity. In particular, for the case of a rectangular chip waveform, it is shown that the MT-CDMA technique proposed earlier and the technique proposed in this paper require /spl alpha/+/spl alpha/log/sub 2//spl alpha/N and 1+(M/N)log/sub 2/M multiplications per chip, respectively, where /spl alpha//spl ges/1 is the number of samples per chip. The reduction in complexity is particularly considerable when N is large.