Spectrum efficient cellular mobile communications

The problem of spectrally efficient communication in a cellular mobile radio system is discussed. Information-theoretical bounds are derived for the spectral efficiency of cellular systems using the channel-reuse method, where each user has a distinct channel that is also reused elsewhere in the system; and for the code-division multiple-access system, where all users use the same spectrum simultaneously and signature sequences are used to distinguish them. It is shown that the CDMA (spread spectrum) bounds are uniformly higher than the channel reuse bounds. Results for practical signalling techniques are compared with the bounds, showing that a real potential for improvement exists using either scheme, but that the potential improvement using spread spectrum is much greater.