Abstract — This paper presents the architecture and protocols of SMesh, a completely transparent wireless mesh system that offers seamless, fast handoff, supporting VoIP and other real-time application traffic for any unmodified 802.11 device. In SMesh, the entire mesh network is seen by the mobile clients as a single, omnipresent access point. Fast handoff is achieved by ensuring that each client is served by at least one access point at any time. Mobile clients are handled by a single access point during stable connectivity times. During handoff transitions, SMesh uses more than one access point to handle the moving client. Access points continuously monitor the connectivity quality of any client in their range and efficiently share this information with other access points in the vicinity of that client to coordinate which of them should serve the client. Experimental results on a fully deployed mesh network consisting of 14 access points demonstrate the effectiveness of the SMesh architecture and its handoff protocol. I.