Handoff considerations in microcellular systems planning

An objective of microcellular networks is to increase frequency reuse by decreasing the size of cell coverage areas. Sufficient overlap in coverage area between adjacent microcells along with appropriate selection of values for the handoff threshold and bias are required to ensure quality reception in handoff regions. These parameters affect the system such that they should not be evaluated in isolation. Assuming handoff algorithms based on received signal strength levels and further assuming the microcell propagation environment to exhibit log-normal shadow fading statistics, an analytical model for studying the effects of varying certain system parameters, (i) radius of the cell, (ii) overlap in coverage area between adjacent microcells, (iii) mobile station velocity, (iv) handoff threshold and (v) bias, is presented. The performance criteria of interest are the probabilities for (i) a late handoff (ii) not being able to find a candidate microcell to handoff to, and (iii) handing back to the original BS after a forward handoff has already occurred.