The challenges of seamless handover in future mobile multimedia networks

摘要

One of the major objectives of third-generation mobile communications systems (TGMS) is the seamless integration of advanced multimedia services over both fixed and mobile networks leading to fixed-mobile convergence. Such systems will support audio, video, multimedia, data, and speech services in a variety of environments with levels of service for mobile users comparable to service currently available for fixed users. To achieve this, TGMS systems must provide adequate performance (in terms of bits per second) for each user in each of the operating environments foreseen. Despite considerable support from many sources (academia, network equipment manufacturers) the homogeneous network architecture that universal adoption of ATM would have provided seems unlikely to become a reality. The very rapid development of ultra-high-speed members of the Ethernet "family" has pre-empted the unique scalability promise of ATM. At the same time, the explosive growth of Internet-based applications and services has ensured that IP will remain the network layer protocol of choice for the vast majority of next-generation systems. This article examines the challenges of handover across a single network domain, between network domains, and specifically between network domains of different levels of QoS. We report on various techniques for supporting mobile terminals, different approaches to handover, and specific issues associated with TCP/IP over wireless links. Finally, we identify some of the more advanced mobile systems R&D projects from the "seamless integration of advanced multimedia services" perspective before generating our conclusions.