Supporting QoS in Broadband Wireless and Wired Access

摘要

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.