Handover rate control in hierarchically structured cellular CDMA systems

The interaction between layers in multilayer cellular systems can be in terms of directing the traffic overflow from the lower layer to the overlaying layer (overflow sensitive cell-layer selection strategy), and/or of classifying the users based on their speed (speed sensitive cell-layer selection strategy). In this paper, we study a hybrid speed/overflow sensitive micro/macro cell-layer selection strategy for two-layer CDMA cellular systems. It is shown that the speed threshold has a major impact on the capacity and the handover rate in such systems. Therefore, here we propose a handover rate control scheme where the speed threshold can be dynamically adjusted according to the handover and blocking rate feedbacks. Simulation results show that the proposed scheme can control the handover rate even when the speed distribution of mobile stations changes with time.