A Re-dial Model for Personal Communications Services Networks

This paper studies the effect of re-dial in a personal communications services (PCS) network. The re-dialing problem for PCS is different from the plain old telephone service (POTS). When using POTS, if a customer receives a busy signal in making a call, or the call does not connect in a timely manner, the customer may make a re-dial call in an attempt to get a connection. Likewise, it is anticipated personal communications services (PCS) network subscribers may also make re-dial attempts when the original call attempt is unsuccessful. However, unlike POTS, PCS has the added complexity of keeping a call connected while the originating caller and/or the terminating caller is moving. Because of this complexity, the effect of re-dial on nomadic communications is a challenging problem that has implications on the design and analysis of PCS networks. Accordingly, this paper presents a model for studying the effect of re-dial on PCS networks. Using this model, several analytical results are presented. These results are then used to validate a Time Warp based, distributed, simulation of the PCS re-dial model. Using the distributed simulation, we vary (i) the probability of re-dial, (ii) the re-dial rate, and (iii) portable mobility and examine each parameter’s effect on (a) the probability of forced termination, (b) the probability of a new call block, (c) the call incompletion probability, (d) expected number of re-dials before a new call attempt is accepted or rejected.