Dennis Bijwaard

Mobility management for sip sessions in a heterogeneous network environment

The next generation of communication networks is expected to create a heterogeneous network environment encompassing an ever-increasing number of different access networks and end-user terminals that will enable the introduction of and provide access to numerous feature-rich end-user services. It is essential that end users be able to roam from one access network to another if they are to enjoy a seamless roaming experience, which is especially important for multimedia applications such as voice, audio, and video. This paper describes how to make such a roaming experience possible in multimedia applications based on Session Initiation Protocol (SIP). It also describes several mobility management solutions and compares the suitability of SIP sessions for roaming across General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), and wireless local area network (WLAN) networks. The comparison is based on the implementation of a prototype. The advantages and disadvantages of each mobility management solution are discussed, as are the issues encountered during the implementation of the prototype.

Supporting QoS in broadband wireless and wired access

Wireless local area network (WLAN), cable, and digital subscriber line (xDSL) are among the most popular broadband access technologies in use today. In all such technologies, the transport capacity provided at the level of the physical medium is non-deterministically shared by different traffic streams generated by a multitude of applications. These traffic streams may have different or even incompatible characteristics (e.g., one may contain bursty best-effort traffic generated by file transfer, another streaming quality of service [QoS] traffic generated by video-on-demand), and they may interfere with one another. To accommodate admitted QoS traffic in a fluctuating available bandwidth and to protect it from high-load statistical traffic patterns, traffic must be regulated. This paper describes a ∗∗∗bandwidth-distribution mechanism for broadband access technologies that uses real-time characteristics of both the active-medium-sensing and the feed-forward control mechanisms. To validate this mechanism, two prototypes are developed, one based on wireless, the other on wired shared media. These prototypes employ legacy network elements without intrinsic QoS capabilities. Finally, we present the results of tests run on these prototypes and draw conclusions from our work.