Abstract
Due to terminal mobility and change of service area, efficient IP mobility support is an
important aspect in UMTS networks in order to provide mobile users negligible packet
loss rate and low handover latency, and thus some level of guaranteed quality-ofservice
(QoS) to support real-time applications. 3G/UMTS has been specified and
implemented as an end-to-end mobile communications system. The underlying
WCDMA access systems manage radio access handover (layer 1) and provide linklayer
mobility (layer 2) in terms of connection setup and resource management. For
the UMTS nodes to have seamless connectivity with the Internet, the UMTS core
networks need to be able to support continuous and no network service session
handover (layer 3 and above). A long IP handover latency results in high packet loss
rate and severely degrades its end-to-end transport level performance. Network-layer
handover latency has therefore been regarded as one of the fundamental limitations in
IP-based UMTS networks. Therefore, it is crucial to provide efficient network-layer
mobility management in UMTS/WCDMA networks for seamless end-to-end TCP
connection with the global Internet.
Mobility of UMTS nodes necessitates extra functionalities such as user location
tracking, address registration and handover related mechanisms. The challenge to
provide seamless mobility in UMTS requires localised location management and
efficient IP handover management. Mobile IPv6 protocol offers a better mobility
support as the extended IPv6 features with mobility mechanism are integrated to the
mobile nodes. To mitigate the effect of lengthy IP handover latency, two well-known
handover reducing mechanisms based on Mobile IPv6 support have been proposed in
the literature. They are designed with hierarchical network management and address
pre-configuration mechanism. Hierarchical management aims to reduce the network
registration time, and fast-handover attempts to minimise the address resolution delay.
S-MIP (Seamless Mobile IP) integrates the key benefits of the above IP mobility
mechanisms coupled with local retransmission scheme to achieve packet lossless and
extremely low handover latency, operating in WLAN environments.
In this thesis, we explore the possible Mobile IP solutions and various IP handover
optimisation schemes in IPv6 to provide seamless mobility in UMTS with the global
Internet. It aims at developing an optimised handover scheme that encompasses the
packet lossless and extremely low handover latency scheme in S-MIP, and applying it
into the UMTS/WCDMA packet data domain. Therefore, the hybrid UMTS-SMIP
architecture is able to meet the requirements of delay sensitive real-time applications
requiring strict delay bound, packet lossless and low handover latency performance for
end-to-end TCP connection during a UMTS IP-based handover. The overall seamless
handover architecture in UMTS facilitates integrated, scalable and flexible global IP
handover solution enabling new services, assuring service quality and meeting the
user s expectations in future all-IP UMTS deployment.
The viability of the seamless mobility scheme in UMTS is reflected through and
validated in our design model, network protocol implementation, and service
architecture. We illustrate the performance gained in QoS parameters, as a result of
converged UMTS-SMIP framework compared to other Mobile IPv6 variants. The
simulation results show such a viable and promising seamless handover scheme in
UMTS on IP handover latency reduction on its end-to-end TCP connection.