Title :
Bounds on spectral efficiency of CDMA and FDMA/TDMA in a cellular system
Author_Institution :
York Univ., Heslington, UK
Abstract :
The paper uses Shannon´s (1949) bound on the capacity of an AWGN channel to calculate bounds on the spectral efficiency of CDMA and FDMA/TDMA with arbitrarily complex coding in a cellular system. In both cases co-channel interference is modelled as Gaussian noise, and it is pointed out that the use of coding justifies this assumption. Both uplink and downlink are considered, with and without voice activation, and in the case of FDMA on the downlink, power redistribution from inactive channels. It is shown that CDMA is more efficient on the uplink even without voice activation, while FDMA/TDMA is more efficient on the downlink, although with voice activation CDMA regains a marginal advantage. It is also pointed out that coding of arbitrary complexity implies sufficient diversity to overcome fast fading.<>
Keywords :
cellular radio; channel capacity; code division multiple access; frequency division multiple access; radiofrequency interference; time division multiple access; white noise; AWGN channel; CDMA; FDMA; Gaussian noise; Shannon´s bounds; TDMA; cellular system; channel capacity; cochannel interference; coding; diversity; fast fading; power redistribution; spectral efficiency; voice activation; Code division multiaccess; Electromagnetic radiative interference; Frequency division multiaccess; Information rates; Land mobile radio cellular systems; Time division multiaccess; White noise;
Conference_Titel :
Spread Spectrum Techniques for Radio Communication Systems, IEE Colloquium on
Conference_Location :
London, UK
