Hysteresis Model for Velocity Based Handoff in Hierarchical Cellular System

Increased system capacity, improved coverage and services to different mobility users assumed importance with the tremendous increase in the number of mobile communication users. Adoption of hierarchical cellular system (HCS) is a way to address these issues. Though HCS has the efficiency to provide cells of different radius and treating the subscribers of higher and lower mobility separately, the disadvantage is that it increases the number of handoffs which in turn increases the processing overhead. In order to reduce the number of handoffs, the hysteresis concept based on the velocity of the mobile user is taken into account by us in this paper. The inclusion of hysteresis concept, allows the mobile user to roam in the same cell if its velocity changes back within a set threshold values. From the simulation results, it is observed that the number of handoffs is reduced considerably in the hysteresis introduced handoff scheme compared with that of conventional scheme. The percentage of microcell overlay in macro cell region is also examined.