US 7,688,865 B2 · Method and system for clock skew and offset estimation

Abstract

Disclosed are a method and system for estimating the skew and offset between two clocks in a computer system. The method comprises the steps of obtaining a first set of data values representing a forward delay between the first and second clocks, and obtaining a second set of data values representing a negative backward delay between the first and second clocks. The method comprises the further steps of forming a lower convex hull for said first set of data values, and forming an upper convex hull, above the lower convex hull, for said second set of data values. The clock offset and the skew between said first and second clocks are estimated using those convex hulls. In a preferred embodiment, this estimation is made by identifying a best clock line between the first and second convex hulls.

Claims18

Dependent claims

A computer implemented method of estimating clock skew and offset between first and second clocks in a computer system, the method comprising the steps of:

obtaining at the computer system a first set of data values representing a forward delay between the first and second clocks;
obtaining at the computer system a second set of data values representing a negative backward delay between the first and second clocks;
generating lower convex hull values on the computer system comprising values of a lower convex hull for said first set of data values;
generating upper convex hull values on the computer system comprising values of an upper convex hull, below the lower convex hull, for said second set of data values;
and
using the lower and upper convex hull values at the computer system to identify a best position between said lower and upper convex hulls to estimate the clock offset and the skew between said first and second clocks.

3 more elements

An estimating system for estimating clock skew and offset between first and second clocks in a computer system, the estimating system comprising the computer system configured for:

generating lower convex hull values on the computer system comprising values of a lower convex hull for a first set of data values representing a forward delay between the first and second clocks, and generating upper convex hull values on the computer system comprising values of an upper convex hull, below the lower convex hull, for a second set of data values representing a negative backward delay between the first and second clocks;
and
using the lower and upper convex hull values on the computer system to identify a best position between said lower and upper convex hulls to estimate the clock offset and the skew between said first and second clocks.

A program storage device readable by a computer system, tangibly embodying a program of instructions executable by the computer system to perform method steps for estimating clock skew and offset between first and second clocks in a processing system, said method steps comprising:

obtaining at the computer system a first set of data values representing a forward delay between the first and second clocks;
obtaining at the computer system a second set of data values representing a negative backward delay between the first and second clocks;
generating lower convex hull values on the computer system comprising values of a lower convex hull for said first set of data values;
generating upper convex hull values on the computer system comprising values of an upper convex hull, below the lower convex hull, for said second set of data values;
and
using the lower and upper convex hull values on the computer system to identify a best position between said lower and upper convex hulls to estimate the clock offset and the skew between said first and second clocks.

3 more elements

Dependencies are inferred from the claim text.

Method and system for clock skew and offset estimation

Life of this patent

Method and system for clock skew and offset estimation

Life of this patent

Abstract

Claims18