Handover Optimisation for Co-Channel WCDMA Heterogeneous Networks

This paper investigates a handover problem occurring with current power control mechanisms in co-channel WCDMA heterogeneous networks. The problem is associated to the mismatch between the required uplink transmit power when a user is communicating to a small cell and an underlying microcellular base-station. As a result, there is a need for significant increases of users' transmit power when handing off from small cell to the macrocell tier. This sudden increase of the transmit power results in increased uplink interference and major SINR drops for existing small cell users. This paper introduces a realistic and efficient solution to adapt the transmit power of the small cell users during the handover regime to prevent such SINR drops. Simulation results confirm significant performance improvement when using the proposed scheme. Keywords - Femtocells, Small Cells, Handover Optimisation, Uplink Power Control, WCDMA, Co-Channel Operation, Heterogeneous Networks.