Combining W-ISP and cellular interworking models for WLAN

It has become apparent that the models for WLAN interworking with cellular networks and W-ISP networks have started to diverge. This potentially results in a situation where WLAN hotspots are unable to simultaneously support both 3G and W-ISP subscribers. The paper discusses this issue in detail and suggests solutions to allow the co-existence of 3G and W-ISP subscribers within the same WLAN hotspot. The first section of this paper provides a brief overview of the functionality required to support the roaming of users between different service provider networks and highlights some of the current interworking techniques to support them. The next section outlines current state of the art interworking proposals that have been developed by various collaborative projects and technical bodies, and summarises the requirements each solution places on the hotspot. The areas where these solutions are incomplete or prevent co-existence are highlighted. The final section discusses how these approaches could be combined to produce a single generic interworking architecture that can be applied to both 3G and W-ISP roaming, and outlines continuing standardisation work in this area.