On the energy requirements of vertical handover operations: Measurement-based results for the IEEE 802.21 framework

The availability of multiple collocated wireless networks and the multi-radio capabilities of contemporary wireless terminals open the potential for optimized wireless connectivity over the heterogeneous wireless environment. Vertical Handover (VHO) operations play a central role in such a setting, enabling the dynamic association of wireless users with the most appropriate wireless networks among those available, towards improved effectiveness according to a host of relevant criteria. At the same time, the efficiency of executing the VHO operations themselves is also a factor affecting the overall system effectiveness. Although several aspects of VHO operations have been investigated in the literature, energy efficiency has not received so much attention yet. Towards closing this gap, the paper investigates the energy requirements associated with the execution of the VHO, by expressing the relevant operations as a sequence of elementary actions and determining the energy expenditure at the involved mobile node for each such action. The results address VHO operations compliant to the widely accepted IEEE 802.21 framework and were obtained through actual measurements taken on a prototype heterogeneous network testbed, employing Linux-powered mobile devices and making use of the Advanced Configuration and Power Interface (ACPI) subsystem for taking energy consumption measurements on them.