Computer modelling of waiting time jitter in digital transport networks

A computer modelling technique is described for the prediction and evaluation of waiting time jitter generation characteristics. The traditional analysis approach has been to apply existing theoretical models which assume ideal circuit implementations and are limited to simple multiplex formats. Time domain simulation techniques based on bit-by-bit sampling have been employed more recently to successfully include the effects of practical realization and complicated formats. An important distinction in this method is that sampling is performed at the frame rate instead of the typically much higher line rate. Nearly identical jitter predictions are obtained using both sampling methods, however significant computational complexity is avoided by calculating phase samples on a frame basis. Time domain methods for the calculation of peak-to-peak and RMS jitter, and frequency domain methods for the calculation of waiting time jitter power spectral densities are also discussed.