High-performance telepointers

ABSTRACT

Although telepointers are valuable for supporting real-time collaboration, they are rarely seen in commercial groupware applications that run on the Internet. One reason for their absence is that current telepointer implementations perform poorly on real-world networks with varying traffic, congestion, and loss. In this paper, we report on a new implementation of telepointers (HPT) that is designed to provide smooth, timely, and accurate telepointers in real-world groupware: on busy networks, on cable and dialup connections, and on wireless channels. HPT maintains performance at usable levels with a combination of techniques from multimedia and distributed systems research, including UDP transport, message compression, motion prediction, adaptive rate control, and adaptive forward error correction. Although these techniques have been seen before, they have never been combined and tailored to the specific requirements of telepointers. Tests of the new implementation show that HPT provides good performance in a number of network situations where other implementations do not work at all - we can provide usable telepointers even over a lossy 28K modem connection. HPT sets a new standard for telepointers, and allows designers to greatly improve the support that groupware provides for real-time interaction over distance.

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INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.3 Group and Organization Interfaces
          Subjects: Computer-supported cooperative work

General Terms:
Human Factors, Performance

Keywords:
groupware performance, message compression, network delay, quality of service, telepointer prediction, telepointers