802.11-Based Wireless-LAN and UMTS interworking: requirements, proposed solutions and open issues Giuseppe Ruggeri * , Antonio Iera, Sergio Polito Department DIMET, Universita ` ‘‘Mediterranea’’ di Reggio Calabria, Via Graziella, Localita ` Feo di Vito, 89060 Reggio Calabria, Italy Available online 6 August 2004 Abstract A consequence of the fast spreading of WLAN implementations aiming at offering communications capability in public hot-spot locations, such as airports and stations, is the growing need of studying possible WLAN and UMTS cellular network integration solutions in a unique augmented infrastructure. In this paper the prospects of an efficient interactionbetweenUMTSand802.11-basednetworksareanalysedinviewoftheachievementofa‘‘GlobalIP’’idea. The authorsÕ intention is to give a picture of the current standardisation activities in this field, to enable the reader to better understand what has been done and what can still be done towards an efficient joint exploitation of both tech- nologies. Therefore, possible scenarios of WLAN–UMTS interconnection/integration are investigated to point out requirements,enablingtechnologies,proposedsolutionsandopenissues.Furthermore,forsomeofthescenarioshigh- lighted,preliminarystudiesoftheauthorsonAAA(Authentication,AuthorisationandAccounting)andQoSmanage- ment are presented. Ó 2004 Elsevier B.V. All rights reserved. Keywords: UMTS; Wireless LAN; WLAN–UMTS interworking; Authentication; Mobility; QoS 1. Introduction Signals of the massive presence and the wide- spread diffusion of the Wireless LAN (WLAN) as a complementary/alternative wireless and mo- bile access methodology to the 3G and beyond mobile radio systems are clearly emerging. The role of the WLAN as a mere alternative to the fixed LAN in the private office environment be- longs to the past. In the near future, such a tech- nology will be part of a common heterogeneous 4G infrastructure made up of segments exploiting different technologies, with the common ‘‘glue’’ represented by the Internet [1]. The current tele- communications scenario is, in fact, characterized by a global system fast converging towards the 1389-1286/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.comnet.2004.07.002 * Corresponding author. E-mail addresses: ruggeri@ing.unirc.it (G. Ruggeri), iera@ing.unirc.it (A. Iera), polito@ing.unirc.it (S. Polito). Computer Networks 47 (2005) 151–166 www.elsevier.com/locate/comnet