A cellular — WLAN vertical handover management system for public transport

This paper presents an ubiquitous connectivity solution for public transportation services and proposes a vertical handover (VHO) algorithm between cellular networks and WLANs, used to implement the ubiquitous connectivity in a heterogeneous wireless network. The system architecture, on which our solution relies, is also presented. The novelty of our approach is that the VHO algorithm takes the decision on the target network based on the background traffic and the link quality, besides the received signal level. Our algorithm exploits the fact that the communication device of the vehicle is equipped with several Wi-Fi interfaces which allow the measurement of the available WLAN´s parameters. The performance of our algorithm is significantly better than those of a classical VHO algorithm which selects the target network based only on the level of the received signal and is similar to that of an optimal VHO algorithm which has complete knowledge of the network parameters.