This paper discusses issues related to the delivery of MPEG-4 video over the Internet and wireless channels. MPEG-4's built-in error resilience capabilities such as flexible re-synchronization markers, data partitioning, header protection, reversible VLCs, and forced intra-frame refresh are described. Methods for using these techniques to build a “smart” network decoder are discussed, and the decoder's video quality is measured for various channel error conditions. The effectiveness and overheads of the various error resilience techniques are compared using both peak signal-to-noise ratio measurements and expert viewing. The use of forward error correcting strategies and the effects of packet sizes and boundaries on video quality are also examined.

This paper describes the design of an OC-12c crossconnect switch developed for the VISTAnet research testbed and installed in GTE's Parkwood central office. The crossconnect switch has been designed as SONET-compliant line terminating equipment and provides switching for up to 16 OC-12c signals. The system consists of up to eight trunk interface cards with two bidirectional OC-12 ports, a synchronous switch card, and a control module with craft interface to provide service monitoring, provisioning, and maintenance functions. Several novel concepts, such as distributed power systems and integrated electro-optical backplane connectors, were incorporated in the design of the crossconnect. The system was implemented using a judicious mix of GaAs, ECL, and CMOS technology. Particular attention was given to equipping the crossconnect with extensive diagnostic capability to facilitate network performance monitoring. Graphic user interface technology provides an easy interface for either operator or maintenance personnel.

VISTAnet is a three-year research effort that involves the deployment of prototype broadband switching systems interconnecting specialized supercomputers. The project partners include BellSouth, GTE, MCNC, North Carolina State University (NCSU), and the University of North Carolina at Chapel Hill (UNC-CH). In addition to the deployment and evaluation of experimental network facilities, the project supports research activities in several areas: gigabit communications, metacomputing, advanced visualization techniques, and medical treatment planning techniques, specifically dynamic radiation therapy planning. VISTAnet is organized as a testbed. It is an environment that has been established to experiment with and evaluate techniques associated with gigabit networking. These experiments include methods for moving data into and out of host computers from the application to the network at gigabit rates, demonstrations and evaluations of an application that requires gigabit networking, and interactive three-dimensional graphics techniques. The overall goal of the testbed is to advance the state-of-the-art in gigabit networking and its application. VISTAnet is one of five gigabit test beds coordinated by the Corporation for National Research Initiatives in cooperation with DARPA and NSF.>