Resilient estimation of synchronisation uncertainty through software clocks
by Andrea Bondavalli; Francesco Brancati; Andrea Ceccarelli; Lorenzo Falai; Michele Vadursi
International Journal of Critical Computer-Based Systems (IJCCBS), Vol. 4, No. 4, 2013

Abstract: Many pervasive and distributed systems require clocks synchronised to a unique and external reference time. Unfortunately, the actual difference between the time of a local clock and the reference time, called offset, is a variable factor that is very hard to compute: synchronisation mechanisms typically estimate the offset, without offering guarantees of closeness of the estimate to the true value. The paper gives a comprehensive description of the Reliable and Self-Aware Clock (R&SAClock), a new software clock that provides both the current time and the synchronisation uncertainty, that is a self-adaptive and conservative estimate of the offset, thus being capable of monitoring synchronisation quality and detecting clock failures. Two different solutions are presented for the evaluation of the synchronisation uncertainty which differ in terms of performance and coverage, and are evaluated in the context of distributed wearable mobile devices intended for railway trackside workers.

Online publication date: Sun, 02-Feb-2014

The full text of this article is only available to individual subscribers or to users at subscribing institutions.

Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.

Pay per view:
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.

Complimentary Subscribers, Editors or Members of the Editorial Board of the International Journal of Critical Computer-Based Systems (IJCCBS):
Login with your Inderscience username and password:

    Username:        Password:         

Forgotten your password?

Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.

If you still need assistance, please email