A Review on Evolution of 3GPP Systems Interworking with WLAN

Evolution of Radio Access Technologies (RATs) is succeeding on its fifth generation (5G). Over the past decade, interworking between heterogeneous RATs has undergone remarkable growth, as there is explosive growth in mobile devices such as smartphones supporting multiple RATs, especially Global System for Mobile communications (GSM), Code division multiple access (CDMA), Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA), Long Term Evolution (LTE), Wireless Local Area Network (WLAN). WLAN is complementary options available to mobile operators when they consider expanding the user data traffic capacity further from the unlicensed spectrum. Since 2004 (Release-6), the Third Generation Partnership Project (3GPP) [1] has initiated to develop a 3GPPWLAN interworking architecture to allow 3GPP service providers to offload data traffic from wide area wireless spectrum to WLANs in indoor locations, hotspots, and other areas with high user density. The initial work in 3GPP specified loose integration (at the core network) and progressively introduced potential enhancements for tighter integration (at the radio access network) based on market trends and demands. This paper provides an insight on the evolution of 3GPP systems interworking with WLAN from 3GPP Release-6 to Release-13. Journal of ICT, Vol. 3, 133–156. doi: 10.13052/jicts2245-800X.322 c © 2016 River Publishers. All rights reserved. 134 R. Rajavelsamy et al.