N. Vulic

Architectural options for the WLAN integration at the UMTS radio access level

Integration of UMTS and WLAN networks can be done at different levels. A promising interworking approach, expected to support seamless vertical handovers, is the one where the WLAN is embedded in the UMTS radio access network. It is suitable for 3G operators, which are provided with extra license-free bandwidth in hot spots. This paper addresses this type of integration, discussing two types of network architecture. These architectures differ in the UMTS interface at which the WLAN is integrated. The focus is put on the WLAN integration at the Iub interface. Several possible architectural options and necessary modifications are discussed. An Iub-based option, where user data is transferred via the WLAN, while the signalling is exchanged over the WCDMA interface is presented more in detail.

Vertical handovers among different wireless technologies in a UMTS radio access-based integrated architecture

The demands for accessing services at high data rates while on the move, anyplace and anytime, resulted in numerous research efforts to integrate heterogeneous wireless and mobile networks. The focus was mainly put on the integration of the Universal Mobile Telecommunications System (UMTS) and the wireless local area network (WLAN) IEEE 802.11, which is beneficial in terms of capacity, coverage and cost. With the advent of IEEE 802.16(e) the attention of the research community was shifted to its interworking, on one side, with complementary WLANs, and on the other, with UMTS for extra capacity. In addition, there has been also research on UMTS interworking with different broadcasting systems, including the Digital Video Broadcasting system for handheld devices (DVB-H). All these research activities resulted in various heterogeneous architectures where the interworking was performed at different levels in the network. In this article, we address the integration at the UMTS radio access level, known also as very tight coupling. This integration approach exhibits good vertical handover performance and may allow for seamless session continuity during the handover. However, it is a technology specific solution, where not all the mechanisms applied to the integration of one wireless technology can be straightforwardly reused for embedding another. This integration approach introduces various modifications to UMTS that have to be standardized, which makes it a long-term solution. We present here the general architecture for the integration at the UMTS radio access level and discuss the extension of the architectural framework for various types of access systems with as few as possible additional modifications. The focus of the work is put on the vertical handovers. We discuss various vertical handovers among WCDMA, IEEE 802.11, IEEE 802.16e and DVB-H in the considered heterogeneous architecture. We present new handover types, describe the vertical handover procedures and provide performance evaluation of the vertical handovers in different scenarios and for different combinations of the wireless access technologies.

DVB-H - UMTS Integration at Radio Access Level

The provision of one-to-many multimedia services to mobile users over scarce wireless resources has to be performed in a cost-efficient way. In addition to various systems optimized for this type of service, such as DVB-H, UMTS was recently enhanced for support of multimedia broadcast and multicast services (MBMS) over the existing infrastructure. Since MBMS provision will reduce the UMTS capacity for its essential point-to-point services, the integration of UMTS and DVB-H may be beneficial. In this paper, we address the integration of DVB-H at the UMTS radio access level. We present an interworking architecture and discuss necessary modifications to UMTS.

Quantitative Comparison of Resource Management Strategies in UMTS-WLAN Integration at the Radio Access Level

The WLAN integration at the UMTS radio access level is a promising interworking approach, which provides the mobile operator with additional license-free bandwidth, enhances vertical handover performance and facilitates common management of all the available radio resources. The benefits are achieved at cost of various modifications of the UMTS radio access network. The modifications may be designed in different ways and may result in different architectural options with different performance. In; this paper, we present quantitative comparison of three architectural options, putting the focus on the initial radio interface selection algorithm.

Integration of Broadband and Broadcasting Wireless Technologies at the UMTS Radio Access Level

The UMTS radio resources are insufficient to support services that demand high bandwidth. Integration of heterogeneous wireless access systems into UMTS may be a way to overcome this problem. In the market, there are different wireless technologies, ranging from those that provide high and cheap bandwidth to those specially tailored for mass multimedia services. In this paper, we address the integration of broadband and broadcasting technologies at the UMTS radio access level. More specifically, we discuss benefits of such integration for mobile operators and present necessary architectural and protocol modifications to the UMTS network.