Complexity Constrained Noise-Free CDMA: Optimal Power Distribution and Spectral Efficiency

constrained noise-free CDMA channel is addressed. Multiuser cooperation is imperative if conventional demodulation is expected to be error free for non-orthogonal spreading sequences. It is found that for such a constraint the power distribution ensuring the most fruitful cooperation is that which assigns equal power to all users. As a result the asymptotic capacity and spectral efficiency are highest when all users transmit with the same amplitude. It is also shown that for such a complexity constrained channel the asymptotic spectral efficiency is a boundless monotonically increasing function of the channel load.