The third-generation (3G) mobile communication systems
provide great coverage, complete subscriber management
and nearly universal roaming. Nevertheless, 3G systems
are subject to the low data rates (2Mbps highest for
WCDMA). WLAN (Wireless Local Area Network) provides hot spot coverage with high data rates (reaches
54Mbps while 802.11 a/g), but is subject to short range
(reaches 100m the furthest) and lacking a roaming and
mobility support. From the users’ point of view, the Integration of WLAN and 3G systems will provide a convenient and attractive way for the user to access network. The users are able to access 3G mobile network
while at high speed travel or access WLAN while moving
slowly or entering a specific area. However, while integrating WLAN and 3G, there are still some problems that
should be considered in terms of authentication and security (such as billing, service continuity and authentication
delay). In this article, we focus on the UMTS (Universal
Mobile Telecommunications System). First, we review
the interworking scenarios and architecture of 3G and
WLAN. Then, we review the standardized authentication
protocol for 3G/UMTS and WLAN interworking; moreover, we will review some papers related to the security
issues and solutions on interworking between 3G/UMTS
and WLAN. We also further make some comparisons to
these schemes on their features and performance. Finally,
we conclude some future works for the interworking between 3G/UMTS and WLAN.