Seamless handover among heterogeneous wireless networks

The present thesis introduces decision criteria for the handover among heterogeneous wireless networks also known as vertical handover. The goal is to select the best network that can support the required service(s) and avoid excessive switching among di erent networks in order to minimize service interruptions and power consumption. Firstly we address the vertical handover between speci c broadcast technologies using a single aggregate function (SAF), then we generalized the approach in order to consider heterogeneous technologies and their possible optimization at link layer. To avoid unnecessary handover in the SAF approach we introduced a probabilistic approach that has minimal computational complexity while maintaining a trade-o between received bits and number of vertical handovers. In the last part of the present thesis we propose an approach based on a multi-criteria decision technique that permits to consider the out-of-service parameter and includes parameters that are a ected by a degree of uncertainty.