Fuzzy layer selection method in hierarchical cellular systems

Hierarchical cellular systems are proposed to accommodate mobile users of different speeds. While the microlayer serves the slow users, the macrolayer serves the fast users. After a handoff request is initiated, we must make a decision determining whether it should go to the micro or macrocell. In this paper, this problem is tackled by making use of the past cell dwell times and occupancies in the target micro and macrocell. We want those mobile users with high velocity to join the macrolayer. It is also desirable to select the target cell which has lower occupancy in order to prevent call blocking. These heuristics are incorporated in a fuzzy layer selection (FLS) algorithm, which is devised in terms of fuzzy set and fuzzy logic. The performance is compared to the popular threshold method in the literature by simulation.