(A) cost model for handoff analysis in a microcell/macrocell system

Abstract

In Microcell/Macrocell cellular system, handoff policy between different layer is critical for the performance of the system. This thesis proposes new handoff policy to be applied between different layers, which is based on the number of handoff duirng a call. The proposed handoff policy directs all calls to macrocells whenever the number of all handoffs within the associated microcells gets over a given threshold. In order to determine the threshold properly, a cost model is developed in one-dimensional Microcell/Macrocell system. The cost includes macrocell blocking cost and microcell handoff cost which are incoporated in a trade-off relation. No research in the literature has considered these two cost aspects to determine the threshold. In the proposed system, the macrocell blocking probability is assumed to Erlang B formula. By approximating the associated cost function, the threshold value is obtained. This effectiveness of the approximation cost function was numerically tested. In experimental result, the approximation method is well fitted for most test cases. The sensitivity of solution is also analyzed.