Analysis of the dynamic time error in a chain of cascading telecom boundary clocks

Time quantization error is the major component of dynamic time error which is caused by the time stamping. Both the constant and dynamic time error components contribute to the time error in a network, which limits the number of clocks, cascaded in a chain. Due to complex network topologies and different network technologies, the limit on the number of intermediate supporting clocks may not meet all the requirements for future systems. In order to ensure a minimum time error, it is important also to keep the dynamic time error low. One of the effective ways is to employ higher timestamp resolutions. In this paper, we analyze the dynamic time error in cascaded homogenous Telecom boundary clocks. The upper bound of the dynamic time error accumulation at the output of the Telecom-time slave clock (T-TSC) node is derived for homogenous time clocks. The effect of timestamp resolution is theoretically discussed. The measurement results in a mobile backhaul network indicate that a high timestamp resolution (e.g., 500 MHz) outperforms the conventional timestamp resolution based on the timestamp frequency of 125 MHz.