SIGNAL-TO-INTERFERENCE CALCULATIONS FOR MODERN TDMA CELLULAR COMMUNICATION-SYSTEMS

Signal-to-interference ratios (SIRs) for time division multiple access (TDMA) systems using frequency hopping, power control, and discontinuous transmissions are calculated for tessellated hexagonal cellular clusters where the transmissions are subjected to an inverse fourth power path loss law and log-normal fading. Graphs of SIR against the number of cells per cluster for different voice activity factors are presented. Sectorisation is considered, and particular attention is given to sectorisation in cells residing in cluster sizes of one, two and three cells per cluster. The calculations are made for both up-link and down-link transmissions. The effect of sectorisation on teletraffic is also considered where it is shown that gains in capacity are accompanied by a decrease in the reuse factor. The investigations focus on a GSM look-alike and it is shown that a three-cell cluster with omnidirectional sites gives the highest capacity, while sectorisation decreases the carried teletraffic but improves link quality.