This document summarizes research on vertical handover between UMTS and WLAN networks. It describes the architectures, algorithms and procedures involved in vertical handover. The key points are:
1. Vertical handover allows seamless switching between cellular (UMTS) and wireless local area (WLAN) networks. This provides benefits like reduced power consumption and lower costs when using WLAN connections.
2. The Universal Seamless Handover Architecture (USHA) is proposed to support both horizontal and vertical handovers with small infrastructure changes. It uses IP tunneling techniques.
3. The Smart Decision Model is used for reliable network selection. It gathers information to choose the best network interface based on factors