An Novel User-Classified Method for Modeling and Analysis of Hierarchical Cellular Networks

As continuing growth in traffic volume from users with varying degrees of mobility in wireless networks, a hierarchical cellular structures (HCS) has been suggested. In this paper, we study the performance of a two-tier microcell/macrocell cellular system with bidirectional call-overflow scheme, where calls are allowed to overflow between the macrocells and microcells, and cell selection in hierarchical architecture based on the velocity of the mobile making the calls. Different from the general layer-classified (macrocell and microcell) analysis, we develop a novel user-classified (fast and slow) modeling method for evaluating the performance of such systems. The user-classified models consist of a fast user model and a slow user model both of which are one-dimension Poisson process transition diagrams instead of complicated overflow traffic model. Theoretical analysis and numerical evaluation show that our analytical model is reliable. Furthermore, strategies of applying handoff queue using our models are examined.