Fast Client-Based Connection Recovery for Soft WLAN-to-Cellular Vertical Handoff

• Published in: IEEE transactions on vehicular technology 2008-03, Vol.57 (2), p.1089-1102
• Main Authors: Azhari, V.S., Smadi, M., Todd, T.D.
• Format: Article
• Language: English
• Subjects: Access network integration; Applied sciences; Attachment; Base stations; Business and industry local networks; Cellular; Cellular networks; Electrical engineering. Electrical power engineering; Electrical power engineering; Equipments and installations; Ethernet networks; Exact sciences and technology; IP networks; Joints; Land mobile radio cellular systems; Leg; Local area networks; Mobile radio mobility management; Mobile radiocommunication systems; mobility management; Networks and services in france and abroad; Performance enhancement; Power networks and lines; Private branch exchanges; Radiocommunications; soft handoff; Stations; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Transmission and modulation (techniques and equipments); Transport protocols; Users connections and in door installation; vertical handoff (VHO); Wireless communication; Wireless LAN; wireless local area network (WLAN); Wireless networks
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2007.905329

Wireless local area network (WLAN)-to-cellular vertical handoff (VHO) involves time-consuming procedures that may significantly disrupt real-time communication. When a soft handoff is anchored by an enterprise private branch exchange (PBX)/gateway, handoff execution can take several seconds due to the time required to establish the cellular-to-PBX call leg. This situation is compounded by the fact that WLAN coverage may sometimes be lost far sooner than a VHO can be triggered and executed. In this paper, we propose and investigate the use of a VHO support node (VHSN) which is attached locally to the wired LAN hotspot infrastructure. When WLAN coverage is lost, the VHSN improves soft-handoff performance by quickly intercepting and redirecting the media flow through the local cellular base station using its cellular end-station attachment. This action can quickly recover the connection before the new cellular call leg is established. Unlike proxy forwarding, wireless multihop, and other infrastructure-modification schemes, the VHSN does not extend wireless coverage or perform infrastructure-based packet forwarding. Instead, the VHSN functions as both an (Ethernet) LAN and a cellular end station. Results will be presented which show the performance improvements that are possible using the proposed mechanism.