Reliable Clock Skew Estimation Algorithm for one-way measurements

Owing to the asymmetry of Internet paths, more and more studies have turned to the measurement for one-way metrics. However, since the clocks at end systems often behave diversely, the synchronization between the end hosts is what we care about all along. In this paper, we firstly propose a general model for clock skew estimation in one-way measurements, which turns the problem of clock skew estimation to the solution of n-dimension equation group, and give the equation group what it needs based on different presumptions. We then present a Piece-wise Reliable Clock Skew Estimation Algorithm (PRCSEA), which introduces the reliability test of estimation results and eliminates the extra presumptions needed by other algorithms, such as only one clock adjustment in the measurements. PRCSEA solves the skew estimation problem in a heuristic way, and it can handle many special cases affecting the estimation of clock skew, such as routing change, clock hiccup and network congestion. PRCSEA is the only algorithm that can handle non-constant clock skew to the best of our knowledge. The time complexity of PRCSEA is O(n*logn), which is the same as that of Paxson´s algorithm.