motivation | topic1 | topic2 | topic3 | topic4 | topic5 | downloads

Topic1: Bandwidth Aggregation

Topic2: Public-area Wireless Networks

Topic3: Video Compression

Topic4: Routing, Scheduling and Power Control

Topic5: Content Shaping & energy consumption modeling

In recent years, explosive growth of the Internet has been a major driving force in the deployment of a variety of wireless technologies. Examples include GPRS, EDGE, CDMA2000, HDR, UMTS. While wireless technologies traditionally were designed to offer circuit-switched voice services, efforts are now underway to integrate mobile radio networks with the Internet to support a rich variety of data applications. Thus far, the focus has been on using only a single wireless interface at a time, and several research challenges related to such use have been explored. Given the scarcity of bandwidth in wireless domain, it’s often the case that no single interface can support data intensive applications like video telephony/conference, telemedicine, and large file transfers. Even though the 3G radio access technology UMTS is touted to provide up to 2Mbps, this is
under the best of conditions, where the channel is dedicated to a single user and the user has excellent radio conditions. In practice, the user is likely to get only a few hundred kbps. This is inadequate - even a low quality 64kbps rate controlled Variable Bit Rate (VBR) interactive video, due to a huge difference between peak to mean rates (about 15), needs at least 300kbps capacity to achieve adequate quality reception.

Restricting wireless technology use to support only a subset of applications that require low bandwidths less appealing and difficult for operators to gain returns on the huge investments made in acquiring license to spectrum. However, when coverage areas of the different wireless technologies overlap, there is no need to restrict oneself to a single interface. The simultaneous use of multiple interfaces permits bandwidth aggregation, thereby allowing support for demanding
applications that need high bandwidths. Further, this can have additional advantages for some applications in terms of increasing reliability, where some or all packets can be duplicated and sent on the multiple interfaces. Also, it can help in mobility management, where the delay associated with handoff can be significantly reduced when an alternate communication path exists.

  ©Copyright 2001-2003 Cal-(IT)2, Adaptive Systems Lab.