A New Handover Decision Management Algorithm in Wireless Overlay Networks

Wireless Overlay Networks (WONs) are multi-layer networks in which mobile nodes (MNs) move freely within cells of the same overlay or between cells of different overlays. Such a structure provides global access to MNs regardless of time and location but poses many challenges. This paper covers the problem of building an efficient handover decision manager (HDM) on each MN so that the MN can decide horizontal and vertical handovers encountered in WONs. The paper studies the current handover decision schemes and proposes a hybrid scheme. The proposed HDM algorithm considers many factors such as the candidate networks' cost, coverage, data rate and traffic load. The algorithm gives accurate and timely decisions and considerably decreases MNs' power consumption at the expense of slightly increased complexity. The simulations, which compare the proposed HDM scheme with two-level thresholding and utility-based schemes, show that the number of unnecessary handovers and MNs' power consumption are decreased considerably while MNs' throughput is not significantly affected by the proposed HDM algorithm.