Link layer support for quality of service on wireless Internet links

Publisher Website
Google Scholar
Abstract
Uring the past few years wireless communications have become very popular, with a multitude of competing technologies and service models available to the public. Cellular telephony (CT) systems are evolving worldwide to fully digital technologies, while wireless local area networks (WLANs) that transparently link wireless hosts to the Internet are becoming cheaper and more interoperable. These systems, despite their differences, share characteristics that set them apart from both traditional (geostationary) satellite and wired links: low propagation delays compared to satellites and high error rates compared to wired links. Their error behavior varies, sometimes rapidly, due to factors such as interference, multipath fading, atmospheric conditions, and possible user mobility, in a generally unpredictable manner. Due to eco- nomic and technological factors, typical wireless links are slower than wired ones, making them the most likely bottle- neck of end-to-end paths. The popularity of wireless systems has generated interest in their integration into the Internet. Although superficially easy, given the minimal requirements of Internet protocols, this task is complicated by hidden protocol dependencies on wired media. In addition, the unpredictable performance of wireless links hinders the evolution of the Internet to quality of service (QoS) provision. In the following section we dis- cuss the causes and extent of these performance problems by reviewing previous work and presenting our own measure- ments. We argue that it is preferable to handle wireless errors at the link layer. We then present a simulation study of various link layer enhancement mechanisms, showing that different solutions are preferable for each type of applica- tion. We thus describe a novel multiservice link layer architec- ture that provides multiple simultaneous services over a single link to support diverse application requirements. We show how our approach can be deployed on the existing Internet or integrated with future QoS-oriented protocols. Finally, we present simulation results showing that our archi- tecture can uniformly improve the performance of multiple applications. Abstract We have developed a novel link layer architecture that provides multiple quality of service points simultaneously over wireless Internet links. Our approach enhances the performance of diverse applications over error-prone links. We discuss the performance problems of Internet protocols over wireless links, presenting as a case study our measurements on a wireless LAN, and argue that it is preferable to handle wireless impairments at the link layer. We present a simulation study of various link layer enhancements, and their impact on TCP and UDP performance. Our results show that different approaches are preferable for each type of application. We thus propose a multiservice link layer approach that supports multiple link layer mechanisms over a single link. Our scheme is transport- protocol-independent and customizable for the underlying wireless link technology. While our approach can be directly deployed on the existing Internet, it also provides support for future QoS-aware protocols and applications. Our simulation results show that our approach uniformly improves the performance of both TCP and UDP applications.

This publication has 13 references indexed in Scilit: