The Study of Cut-off Priority Handoff Strategy in Multitier Cellular Systems

Abstract

In this paper, we study the handoff overflow scheme in a multitier cellular system where microcells are used to address the high-teletraffic but primarily slow mobility areas, and macrocells are overlaid over the microcells to cater primarily to low-teletraffic but high mobility areas. The proposed handoff scheme is a flexible bi-directional cut-off priority scheme where handoffs are allowed in both directions, from low to high tier or from high to low tier. To investigate the loss probability, the threshold of the channels occupied and the channels lent out in each tier are studied and are obtained by simulation. The performance measures of the system using the BCOPH scheme are compared with those using the uni-directional handoff scheme. The results show that the sets of threshold values can effectively reduce the average loss probability which results in an increase in the total system capacity.