Patent ID: 6661810
Filing Date: 2003-12-09
Classification: H04J,H04L

Abstract:
A method of estimating the skew between a sender clock and a receiver clock on a network, comprising:for a set of packets sent over a network, obtaining a set of measurements consisting of the time duration between a first packet's departure and each subsequent packet's departure consistent with the time measured by a sender clock; obtaining a calculated set of delay measurements consisting of the amounts determined by subtracting the time duration between the first packet's departure and each subsequent packet's departure as measured by the sender clock from the time duration between the first packet's arrival and each subsequent packet's arrival as measured by the receiver clock; defining a feasible region of solution for an estimate {circumflex over (&agr;)} of the ratio between the speed of the sender clock and the speed of the receiver clock and for an estimate {circumflex over (&bgr;)} of the end-to-end delay of the first packet consistent with the receiver clock, wherein the feasible region is defined by the following condition: Ndi-(Î±^-1)&it;â€ƒ&it;Ntis+Î²^&GreaterEqual;0,1&leq;i&leq;Nand minimizing the vertical distance between the line and all delay measurements according to the formula min&it;{&Sum;i=1N&it;â€ƒ&it;(di~-(Î±^-1)&it;Ntis+Î²^)}