Analytical models for call blocking and dropping in sectorized cellular networks with fractional frequency reuse

In this paper, we construct mathematical models to analyze the probabilities of new call blocking and handoff call HC dropping for a sectorized cellular network with fractional frequency reuse FFR. Because a sectorized FFR network SFN consists of two areas, the super group SG and the regular group or sectors, three different types of HCs may happen when a mobile station MS moves from the SG to a sector, from a sector to the SG, or from one sector to another sector. To characterize three types of HCs, we first derive the area transition probability, which is defined as the reciprocal of MS's average residence time in an area i.e., sector or SG. Moreover, we construct the model of Markov chains and derive the state transition rates. Then on the basis of the stationary probabilities of Markovian states, we derive the three types of blocking probabilities of new calls and two types of dropping probabilities of HCs. Finally, we conduct extensive numerical simulations. From the results of numerical simulations, we reveal two important rules for choosing the optimal radius of the SG, with which the system blocking and dropping probability can be effectively minimized. Copyright © 2014 John Wiley & Sons, Ltd.