Impact of transmission delay on ISDN videotelephony

In this paper, the design and results of an experimental study are presented which was conducted in order to assess subjectively the impact of transmission delay on ISDN videotelephony. This study was undertaken using two 64-kbit/s videotelephones which were connected over links incorporating simulated one-way circuit propagation delays of 0 ms, 250 ms, and 500 ms. From the results obtained it was concluded that ISDN videotelephony is weakly impacted by propagation delay. In general, no significant performance degradation was observed between terrestrial and single-hop satellite connections.<>