Asynchronous Source Clock Frequency Recovery through Aperiodic Packet Streams

TL;DR

This paper introduces two novel schemes for asynchronous source clock frequency recovery in packet networks, capable of handling aperiodic streams without a common reference clock, outperforming traditional PLL-based methods in convergence speed.

Contribution

It formulates asynchronous SCFR as a regression problem and proposes RLS and heuristic schemes that improve estimation accuracy and convergence speed.

Findings

RLS-based scheme achieves faster convergence than PLL.

Heuristic method provides comparable estimates with simpler implementation.

Both methods outperform conventional PLL-based schemes.

Abstract

We consider the most general case of source clock frequency recovery (SCFR) in packet networks, i.e., asynchronous SCFR through aperiodic packet streams, where there is neither a common reference clock nor any relation between packet generation intervals and a source clock frequency. We formulate the problem of asynchronous SCFR with timestamps as a linear case of regression through the origin (RTO) and propose two schemes, one based on recursive least squares (RLS) method and the other based on simple heuristics of cumulative ratio of interarrival and interdeparture times, which provide better estimates of the source clock frequency with faster convergence than conventional phase-locked loop (PLL)-based schemes.