Optimal radio capacity for an adaptive hybrid DS/FFH CDMA system in rayleigh fading

An adaptive hybrid direct-sequence/fast frequency hopping code-division multiple-access (DS/FFH-CDMA) system operating in a Rayleigh fading environment is considered and its spectral efficiency, expressed in (bits/sec/Hz), is estimated in terms of the theoretically achievable average channel capacity (in the sense of information theory) per user. The analysis covers the operation over a broadcast single-cell time-varying system and leads to a simple closed-form expression for the optimal number of simultaneously active users based on the maximization of the achieved spectral efficiency