Estimation of spectral efficiency for MC/DS-CDMA in cellular systems (original) (raw)

Spectral efficiency is of primary concem in the design of future wireless communications systems. The spectral efficiency achieved by a multicarrier direct-sequence code-division multiple-access (MCDS-CDMA) cellular system operating in a mobile radio environment with Rayleigh fading, is investigated. Spectral efficiency is evaluated in terms of channel capacity (in the Shannon sense) available to each user, estimated in an average sense. It is analytically shown that, under normalized conditions, MCDS-CDMA spectral efficiency, on downlink, is higher than that of single-carrier DS-CDMA (SCDS-CDMA). This result is justified by the combination of path-diversity reception, achieved by conventional coherent RAKE receiver, and frequency diversity provided, in a fading environment, by frequencydivision multiplexing on a set of orthogonal carriers.