Perpustakaan Digital ITB

A recent second generation highcapacity mobile radio telephone system in Japan employs selection diversity with two branches on the mobile receiver to counteract co-channel interference from distant base stations operating with identical frequencies. From an actual point of view it seems more reasonable to assume that the fluctuations of signal carrier envelopes on the mobile receiver are approximated by the m-distribution proposed by Nakagami when we try to investigate fading statistics for land mobile radio not only in urban areas but in suburban or open areas. The m-distribution is a generalisation of the Rayleigh distribution and it can take account of the influence of a superimposed specular component other than scattered and reflected waves. The probability density function of the wanted signal envelope and its characteristic function for selection diversity in the m-fading channel are derived in conveniently closed form, and the probability of co-channel interference that the wanted signalcarrier to interference power ratio (CIR) is less than a specified protection ratio is calculated. The results obtained will serve to decide the modulation system employed and to estimate the frequency re-use distance, the number of channel groups, and the efficiency of spectrum use in cellular mobile radio.