IMPROVED ASSESSMENT OF INTERFERENCE LIMITS IN CELLULAR RADIO PERFORMANCE

Reuse distance and cluster size are evaluated for cellular mobile radio systems. Rayleigh fading, log-normal shadowing, and area mean power inversely proportional to the fourth power of propagation distance are considered, using the technique of Schwartz and Yeh for determining the probability density function of the sum of several log-normal variables in order to obtain the cochannel interference probablities. These results are used for analyzing the radio spectrum efficiency, taking also traffic intensity into consideration. Different modulation methods, namely, analog FM with 30- and 12.5-kHz channel spacing, SSB with 5-kHz spacing, and digital modulation with 25-kHz channel spacing, with adequate protection ratios, are compared. An example of the calculation of system bandwidth and cluster size is presented using this procedure.