Analytical evaluation of blocking probability in a mobile radio system with directed retry

The blocking probability in a cellular network implementing directed retry (DR) is analyzed as a function of the main characteristics of the scenario (the density of base stations), the propagation model (path loss and shadowing), and the speed of mobiles. The analytical approach allows the evaluation of the blocking probability as a function of the maximum number of cells that can be considered at call setup by the DR algorithm. It is shown that the effectiveness of the DR strategy depends on the values of the variance of shadowing and the path loss model. Moreover, the blocking probability is found to be approximately independent from the mobile speed. The analytical results are compared to those obtained by means of simulation: a good agreement has been found, and the analytical model has been shown to be able to reflect the main effects of propagation and mobility on the advantages of DR in a real cellular network.