Timely Updating: Principles and
National Science Foundation Project
NSF Award 1717041
October 14, 2019
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
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
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:
- State Dependent Updating optimized updating for sources subject
to energy and power constraints in sending updates through a
time-varying service facility.
- Status Update Multiple Access protocols for wireless sensors
sending updates through a shared random access channel.
- Real-time Universal Data Compression: the AoI performance of
universal streaming source coding systems for discrete random sources
- Remote Video Updating: AoI-based optimization of the delivery of
surveillance video frames
- PI Roy Yates continues to grind away.
- PhD student Amir Behrouzi-Far (supervised by Emina Soljanin) just
started working on AoI
- PhD student Jing Zhong just graduated.
- M.S. student Feeby Salib just graduated.
- PhD student Mehrnaz Tavan graduated in October 2017.
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
 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.
 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.
 R.D. Yates, J. Zhong, and W. Zhang. Updates with multiple service
classes. In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), July 2019.
 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.
 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.
 A. Garnaev, J. Zhong, W. Zhang, and R.D. Yates. Maintaining
information freshness under jamming. In Infocom Workshop on Age of
Information, April 2019.
 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.
 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.
 R. D. Yates. Status updates through networks of parallel servers.
In Proc. IEEE Int’l. Symp. Info. Theory (ISIT), pages 2281–2285, June
 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
 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.
 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.
 Roy D Yates. The age of information in networks: Moments,
distributions, and sampling. arXiv preprint arXiv:1806.03487,
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