Timely Updating: Principles and Applications
National Science Foundation Project
NSF Award 1717041

October 14, 2019

Project Synopsis

With the emergence of cyber-physical systems, real-time status updates have become an important and ubiquitous form of communication. Applications that employ vehicular status messages, security reports from computers, homes, and offices, and surveillance video from remote-controlled systems need status updates to be as timely as possible but this is typically constrained by limited network resources.

This tension has led to the introduction of new performance metrics based on the Age of Information (AoI) that capture how timely is one’s knowledge of a system or process. AoI-based optimization of both the network service facility and the senders’ updating policies has yielded new and even surprising results that ultimately will increase the reliability of vehicular safety warning systems, reduce the bandwidth needed for video monitoring, and increase the energy efficiency of sensor networks.

Project Objectives

Much of the recent work on AoI has been directed toward an analytic understanding of AoI using mathematical models. While the analysis of basic models and methods has continued, the merits of AoI also need to be studied in the context of specific applications:



Educational Outreach

In Fall 2018, this Timely Updating project was the basis for the ECE 559 Advanced Topics in Communication course on Age of Information. In this graduate course, which included three women students, the underlying material was traditional  stochastic processes (renewal processes, Markov chains, queueing theory, limits of time averages, etc.) but the driving applications were AoI-based.  The students seemed to enjoy seeing traditional topics through the lens of AoI. Course project topics included ”AoI in broadcast systems with energy harvesting sources”, ”Age analysis of CSMA”, ”Age in depth-based routing for underwater sensor networks.” As instructor, I received useful feedback on teaching the Stochastic Hybrid Systems (SHS) approach to AoI calculation.


[1]   Roy D. Yates and Sanjit K. Kaul. The age of information: Real-time status updating by multiple sources. IEEE Trans. Info. Theory, 65(3):1807–1827, March 2019.

[2]   J. Zhong, R.D. Yates, and E. Soljanin. Two freshness metrics for local cache refresh. In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), pages 1924–1928, June 2018.

[3]   R.D. Yates, J. Zhong, and W. Zhang. Updates with multiple service classes. In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), July 2019.

[4]   Tanya Shreedhar, Sanjit K. Kaul, and Roy D. Yates. An age control transport protocol for delivering fresh updates in the internet-of-things. In 20th IEEE International Symposium on A World of Wireless, Mobile and Multimedia Networks (WoWMoM), 2019.

[5]   J. Zhong, W. Zhang, R.D. Yates, A. Garnaev, and Y. Zhang. Age-aware scheduling for asynchronous arriving jobs in edge applications. In Infocom Workshop on Age of Information, April 2019.

[6]   A. Garnaev, J. Zhong, W. Zhang, and R.D. Yates. Maintaining information freshness under jamming. In Infocom Workshop on Age of Information, April 2019.

[7]   J. Zhong, R. D. Yates, and E. Soljanin. Timely lossless source coding for randomly arriving symbols. In 2018 IEEE Information Theory Workshop (ITW), pages 1–5, Nov 2018.

[8]   J. Zhong, R.D. Yates, and E. Soljanin. Multicast with prioritized delivery: How fresh is your data? In Signal Processing Advance for Wireless Communications (SPAWC), pages 476–480, June 2018.

[9]   R. D. Yates. Status updates through networks of parallel servers. In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), pages 2281–2285, June 2018.

[10]   S.K. Kaul and R.D. Yates. Age of information: Updates with priority. In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), pages 2644–2648, June 2018.

[11]   J. Zhong, R.D. Yates, and E. Soljanin. Minimizing content staleness in dynamo-style replicated storage systems. In Infocom Workshop on Age of Information, April 2018. arXiv preprint arXiv:1804.00742.

[12]   R. D. Yates. Age of information in a network of preemptive servers. In IEEE Conference on Computer Communications (INFOCOM) Workshops, April 2018. arXiv preprint arXiv:1803.07993.

[13]   Roy D Yates. The age of information in networks: Moments, distributions, and sampling. arXiv preprint arXiv:1806.03487, abs/1806.03487, 2018.

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