Energy requirements of secure vertical handover operations in the 802.21a framework

IEEE 802.21 is a widely accepted standard providing a media-independent framework and services for enabling seamless handovers among heterogeneous wireless environments. The IEEE 802.21a standard complemented the original specification in an important direction, namely the provision of security mechanisms for handover-related signaling messages and services. However, although the new standard gives a detailed description of the incorporated security mechanisms and of the relevant changes to the structure of the signaling messages, it does not discuss the pros and cons of each security method, with respect to their energy efficiency. This work attempts to fill this gap, by providing simple yet descriptive analytical expressions for calculating the additional energy expended in mobile devices under handover due to the 802.21a security enhancements. These expressions are validated through measurements on a prototype heterogeneous network testbed. The results provide useful hints when choosing the appropriate protection method in devices with tight energy constraints.