Very Tight Coupling of Wireless LANs and UMTS Networks: A Technical Challenge and an Opportunity for Mobile Operators

Abstract

Coupling of Wireless LANs like IEEE 802.l1a1b or HIPERLANI2 systems with Public Land Mobile Networks (PLMNs) like GSM or UMTS offers benefits for both operators and users. Coverage and capacity of an operator's network can be extended with equipment expected to be considerably cheaper than for PLMN coverage. Thus, the operator can participate in the expected WLAN boom. Its customer experiences homogenous access to services with high data rate. PLMNs and WLANs should be considered as complementary systems: PLMNs provide universal coverage and high mobility support, while pico-cellular WLANs will be applied in hot spot areas, offering high data rates (up to about 45 Mbitls/cell in HIPERLANI2). Several levels of interworking are currently being defined by the relevant standardisation bodies. Tight and Very Tight Coupling integrate the WLAN into a unified Radio Access Network. But PLMNs and WLANs are based on different design philosophies. Chances, problems, and possible solutions are discussed in this paper.

A Framework for Integration of Different WLAN Technologies at UMTS Radio Access Level

“…In particular, we concentrate on the WLAN integration at UMTS radio access level that was studied within the Beyond 3G [1] project, a Dutch project on the integration of heterogeneous mobile networks. This approach was introduced in [2] and also discussed in [3]. The interworking architecture presented in [4] is applicable to any WLAN technology, although, due its prevalence in the market, IEEE 802.11b was considered.…”