Handover-verkehr und sein einfluß auf die blockierungswahrscheinlichkeit zellularer mobilfunksysteme

In contrast to fixed networks there is a new type of traffic when mobile cellular networks are considered, namely the handover traffic. To determine the performance parameters of the system like the blocking probabilities, a precise analysis of the arrival process of the handover events in a cell is required. The application of a Poisson process is important for an analytical determination of the blocking probability employing the Erlang-B formula. But the arrival process of the handover events is highly dependent on the dwell time distribution of the subscribers within the cell and therefore on the distribution of the channel holding time. In this paper the impact of the dwell time distribution and thus the distribution of the channel holding time on the distribution of the interarrival times of the handover events is investigated by considering both an isolated cell as well as a general cellular system. By help of these results one may decide on the applicability of the Erlang-B formula in different mobility scenarios. Moreover, the required conditions of the applicability of the Erlang-B formula are mathematically proved and the consequences by neglecting them are demonstrated.