One of challenges of the WATM is providing the negotiated QoS during handoff. It should be considered that the virtual connection cannot always meet guaranteed QoS in wireless environment during/after the handoff execution due to mobility management, limited radio resources and fluctuating network conditions. Micro cell size, which produces more handoff makes it more difficult. An adaptive QoS management scheme is required in order to minimize dropping the virtual connection. We design a handoff network model and cell structure for seamless handoff scheme in WATM networks. In order to realize adaptive QoS management we also adapt the dynamic state at which QoS re-negotiation is executed to meet the negotiated QoS during handoff. In order to localize the impacts of handoff and enable fast and reliable handoff we design the seamless handoff scheme which provides efficient inter-cluster handoff and propose location management with multi-tier addressing based on the network model for QoS-based multimedia services.