Περίληψη:
Spectral efficiency is of primary concern in the design of future
wireless communications systems. The spectral efficiency achieved by a
multicarrier direct-sequence code-division multiple-access (MC/DS-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, MC/DS-CDMA spectral efficiency, on downlink, is
higher than that of single-carrier DS-CDMA (SC/DS-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 frequency-division multiplexing on a set of
orthogonal carriers.
