Self-stabilizing Byzantine Clock Synchronization with Optimal Precision

TL;DR

This paper improves Byzantine fault-tolerant clock synchronization by refining algorithms for better skew bounds, extending to clock rate synchronization, and making the system self-stabilizing with minimal communication overhead.

Contribution

It introduces a refined algorithm with improved bounds, extends synchronization to clock rates, and develops a self-stabilizing scheme preserving high precision.

Findings

Enhanced skew bounds and frequency offset limits.

Successful extension to synchronize clock rates.

Achieved self-stabilization with minimal communication.

Abstract

We revisit the approach to Byzantine fault-tolerant clock synchronization based on approximate agreement introduced by Lynch and Welch. Our contribution is threefold: (1) We provide a slightly refined variant of the algorithm yielding improved bounds on the skew that can be achieved and the sustainable frequency offsets. (2) We show how to extend the technique to also synchronize clock rates. This permits less frequent communication without significant loss of precision, provided that clock rates change sufficiently slowly. (3) We present a coupling scheme that allows to make these algorithms self-stabilizing while preserving their high precision. The scheme utilizes a low-precision, but self-stabilizing algorithm for the purpose of recovery.