Analysis of Intersystem Handover: UMTS FDD & WLAN
Reshan Samarasinghe, Vasilis Friderikos, A.H. Aghvami
Centre for Telecommunications Research, King’s College London.
Abstract: In today’s world not only has mobile communication systems become more com-
petitive, it has also become heterogeneous and globally networked . Today’s mobile phone
users expect services which stretch beyond a simple audio conversation. Therefore it would
not only depend on a traditional single traffic type, but on multiple traffic types. From a
multi-service point of view, no radio system can effectively cover all services desired. Conse-
quently it is necessary that integrating different Radio Access Technologies (RAT) are given
prominence for future needs. This paper discusses the methods which have been proposed by
the Third Generation Partnership Project (3GPP) in interworking Universal Mobile Telecom-
munication System(UMTS), using Frequency Division Duplex (FDD) transmission mode and
Wireless Local Area Networks (WLAN); how and why interworking is possible, and finally a
brief insight to a comparative analysis between interworking and integrating.
One of the main features of the next generation systems, usually referred to as systems beyond 3G, is
represented by the inter-operation of different fixed and mobile networks. Contrary to horizontal handover
which is forwarding of an active connection from one cell to another of the same RAT, an inter-system
handover implies switching from a serving cell of a given RAT to another RAT, e.g. UMTS FDD to
WLAN. Depending on the level of integration that is necessary numerous approaches can be taken to
combine different RATs. When the integration between different technologies are close, the provisioning
of the service is more efficient and the choice of the mode in order to find the best radio access is faster.
This could, for example greatly affect real time flows. On the contrary, a higher level of integration
means providing a greater effort in the definition of interface