Performance Design and Analysis of Handoff in Hierarchical Wireless Networks

The sustained increase in users and the request for advanced services are some of the key motivations for considering the designing of Hierarchical Cellular Networks (HCN). HCN can provide high system capacity, efficient channel utilisation, and an inherent load-balancing capability. In this type of system, calls blocked in a microcell flow over to an overlay macrocell. In this paper, a two layer macrocell/microcell HCN system model is considered. Performance models for microcells and macrocell are developed through the use of 1-D and 2-D markov process, respectively. In the proposed CAC, the HCN system supports both fast and slow mobility users. The macrocells handle the fast-mobility users while the microcells serve the slow-mobility users. In the microcells, a combination of sub-rating, call bounding and handoff queueing schemes have been used, while in the macrocell the call bounding scheme has been used. The results show that the proposed scheme reduces both the dropping probability of handoff calls and the blocking probability of new calls. The effect of sub-rating in the microcell on the voice quality is also studied, and the results show that the voice quality will degrade when the number of channels sub-rated is increased, and voice quality can be improved by increasing the number of microcells.