Analysis of handoff in a location-aware vertical multi-access network

Integration of WLAN hotspots into next generation cellular networks requires considerations on location management, resource allocation, handoff algorithms and their sensitivity to mobility related features such as velocity of the mobile and the handoff delay. This article presents architecture for seamless location-aware integration of WLAN hotspots into cellular networks and provides an analysis for an optimal handoff decision in moving in and out of a hotspot. For a mobile station, it may be beneficial to know the whereabouts of the hotspots in order to facilitate optimal handoff between the two access networks. In an integrated cellular-WLAN environment, one has to consider location management as part of mobility management due to differences in the cell sizes of the two overlapping technologies. Location information acquired through GPS may be helpful in some cases for advanced location management. In this paper we propose a location-aware architecture to support vertical roaming among heterogeneous wireless access networks. The article includes a description of a preliminary system architecture and the procedures and algorithms needed to implement mobility and location management. In conclusion, a comparison is given of two handoff algorithms (power and dwell-timer based) for moving-in and moving-out transitions, and their sensitivity to mobile velocity and handoff delay.