Pre-scheduled handoff for service-aware and seamless internet access

Existing handoff techniques connect a user to a nearby access point whenever it is available along the user's moving path. If the path is not fully Wi-Fi covered, the user may suffer from frequent disconnections. In this work, we propose a pre-scheduled handoff scheme, which determines a quality-aware path so a mobile user can move across an Urban Wi-Fi Mesh network with uninterrupted Internet access at a required data rate. This scheme has several novel techniques. Firstly, by concurrently considering the received signal strength at mobile users and the load of mesh routers (MRs), we design two path finding metrics, contact weight and handoff count, according to the coverage information. Secondly, to measure the path metric in a practical mesh network with irregular and dynamic MR coverage, we propose a light-weight Bloom-filter-based polling algorithm to discover the mobile stations (called STAs) covered in MR, and a Bloom-filter-based probabilistic algorithm to estimate the degree of coverage overlapping among MRs. Thirdly, based on the path metrics, our proposed scheme supports flexible rate requirements from mobile users through a fully distributed multi-service-class path finding algorithm. Our pre-scheduled scheme considers both mobility and connection requirement, so that the mobile user can continuously access the Internet with the expected data rate. To our best knowledge, this is the first work to ensure seamless Internet access with rate consideration by finding a Wi-Fi covered geographic path in a practical wireless mesh network. We have carried out extensive simulations, and the simulation results show that the pre-scheduled handoff scheme can provide appealing high data rate to mobile user with minimum handoff delay.