Optimal hop number of adaptive hybrid DS/FFH CDMA in Rayleigh fading

An adaptive hybrid direct-sequence/fast frequency hopping code-division multiple-access (DS/FFH-CDMA) system operating in Rayleigh fading is described and its spectral efficiency is estimated in terms of the theoretically achievable average channel capacity (in the Shannon sense) per user. The operation of the considered adaptive hybrid DS/FFH-CDMA system over a broadcast single-cell time-varying channel is examined and leads to a closed-form expression for the optimal number of hops with respect to the achieved spectral efficiency.