Analysis of vertical handover time in heterogeneous wireless networks

In a heterogeneous wireless network, connectivity is simultaneously available using different radio networks with overlapping coverage areas. A mobile user equipment with a multiple mode card that can work under various frequency bands and modulation schemes can switch from one technology to another in order to maintain communication. This procedure known as a vertical handover (VHO) provides the benefit of utilizing the higher bandwidth and lower cost of wide local area networks as well as better mobility support and larger coverage of cellular networks. The authors investigate details of the VHO procedure from WLAN (Wireless Local Area Network) to the 3GPP Long Term Evolution (LTE). The VHO procedure includes 40 signaling messages, which are responsible for authorization and resource allocation in the target LTE network. The authors analyze the VHO sojourn time and its 95 percent quantile using a multiphase queuing system with background traffic.