Conclusions and Future Directions

After introducing the 3G networks and standards, this chapter presented five
interconnections and seamless intertechnology handover dealing with interworking
aspects between IEEE 802.11 WLAN and UMTS. The concepts
discussed focused on the network layer and the link layer in order to minimizing
effects on existing networks and technologies, especially at the lower
layers such as MAC and PHY.
Based on the arguments presented for the given interworking
approaches, mobile IP-based interconnection architecture is selected as the
most suitable solution. IP layer mobility management provides an efficient
way to interconnect heterogeneous packet-oriented networks. Interworking
cannot be handled within a proprietary protocol of one network technology;
it has to be handled either in the existing layers above or a new layer has to be
added solely for the purpose of handling intertechnology roaming. In either
case, there is a need for modification of existing protocols, at least between
the MS and a network entity that handles the mobility.
Finally, intersystem handover is a topic that will become more and
more important in the evolutionary path towards UMTS and 4G wireless
infrastructures. Mobile IP-based intertechnology roaming is an evident step
on this path. The fast handover required for real-time services have to be
studied further within a platform.
Current telecommunication and computer networks are on the verge
of providing mobile multimedia connectivity, where nomadic users would
have ubiquitous access to remote information storages and computing services.
As an evolutionary step towards the 4G mobile communications, mobility
in heterogeneous IP networks with both UMTS and IEEE 802.11
WLAN systems is seen as one of the central issues in making the 4G of telecommunication
networks and systems.