This document discusses handoff schemes for high-speed mobile internet services. It describes the issues with mobility and different types of handoffs between networks. It proposes two approaches - a prediction-based approach that performs authentication of neighboring access points in advance, and creating a heterogeneous mobile switching and management network (HMSMN) to support seamless vertical handoffs across different wireless technologies. The HMSMN would detect available networks, make handoff decisions, initiate handoffs using mobility protocols like MIP, and support tight integration with mobility protocols for seamless connectivity during vertical handoffs.