A tremendous proliferation of mobile computing devices is made for mobile users demanding a network environment with continuous connectivity as wireless network matures. However, with current wireless technologies, when mobile users traverse into adjacent networks, connectivity is compromised due to handoff latency. Moreover, there is no connectivity provided while mobile users remain in areas not covered by wireless network infrastructure. In this paper, we present an architecture that uses mobile location management as the basic platform to improve connectivity for mobile users in both connected and disconnected areas. Seamless connectivity is provided when mobile user is traveling between adjacent networks and virtual connectivity is provided while mobile user is located in areas without any wireless network coverage.

As the number of Mobile IP (MIP) [C. Perkins, (1996)] users grow, so will the demand for delay sensitive real-time applications, such as audio streaming, that require seamless handoff, namely, a packet lossless Quality-of-Service guarantee during a handoff. Two well-known approaches in reducing the MIP handoff latency have been proposed in the literature. One aims to reduce the (home) network registration time through a hierarchical management structure, while the other tries to minimize the lengthy address resolution delay by address pre-configuration through what is known as the fast-handoff mechanism. We present a novel seamless handoff architecture, S-MIP, that builds on top of the hierarchical approach [H. Soliman et al. (2002)] and the fast-handoff mechanism [G. Dommety et al. (2002)], in conjunction with a newly developed handoff algorithm based on pure software-based movement tracking techniques [Z.-G. Zhou et al. (2002)]. Using a combination of simulation and mathematical analysis, we argue that our architecture is capable of providing packet lossless handoff with latency similar to that of L2 handoff delay when using the 802.11 access technology. More importantly, S-MIP has a signaling overhead equal to that of the well-known 'integrated' hierarchical MIP with fast-handoff scheme [H. Soliman et al. (2002)], within the portion of the network that uses wireless links. In relation to our S-MIP architecture, we discuss issues regarding the construction of network architecture, movement tracking, registration, address resolution, handoff algorithm and data handling.