earticle

영어

In this paper we present the comprehensive survey on the clock synchronization algo-rithms, which should be considered for the measurements of the network delay. We catego-rize the clock synchronization algorithms into two basic types according to how they acquire synchronization between clocks, which are external source based schemes and end-to-end measurement based schemes. While external source based schemes are the synchronization methods using centralized time source such as NTP, GPS and IEEE 1588 to have global synchronization for all end hosts, end-to-end schemes obtain synchronization information through network measurements between end hosts. We briey introduces some algorithms in both categories. However, we have focused more on the end-to-end schemes which can be classied again into online and oine shemes according to whether they can be applied for real time operation. We survey the recent progresses on these end-to-end algorithms and special concerns are on the estimation of true the one-way delay without the eect of clock skew. The problems in depolying each end-to-end scheme are also described. The potential further research issues in online one-way delay estimation are discussed.