Channel Allocation Algorithm and Access Strategy in Two-tier Cellular System

A two-tier cellular system with a number of small micro-cells overlaid by one large macro-cell is studied. Two channel allocation strategies, Macro-cell-Centered Access Strategy and Micro-cell-Centered Access Strategy, are proposed for the low mobility calls. The system objective is to minimize handover rate with constraint of call blocking and dropping rates (total lost rate) below certain QoS criterion (such as 2%). Results obtained through analytical model and computer simulations are compared. Two strategies are also compared by a comprehensive cost function composed of call loss rate and handover rate, and their applicable conditions are given by parameters including call mobility, holding time and micro-cell radius.