{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T15:46:38Z","timestamp":1772120798544,"version":"3.50.1"},"reference-count":107,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2022,5,31]],"date-time":"2022-05-31T00:00:00Z","timestamp":1653955200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NSF Grants","award":["CCF 17-13977"],"award-info":[{"award-number":["CCF 17-13977"]}]},{"name":"NSF Grants","award":["ECCS 18-07348"],"award-info":[{"award-number":["ECCS 18-07348"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>We consider real-time timely tracking of infection status (e.g., COVID-19) of individuals in a population. In this work, a health care provider wants to detect both infected people and people who have recovered from the disease as quickly as possible. In order to measure the timeliness of the tracking process, we use the long-term average difference between the actual infection status of the people and their real-time estimate by the health care provider based on the most recent test results. We first find an analytical expression for this average difference for given test rates, infection rates and recovery rates of people. Next, we propose an alternating minimization-based algorithm to find the test rates that minimize the average difference. We observe that if the total test rate is limited, instead of testing all members of the population equally, only a portion of the population may be tested in unequal rates calculated based on their infection and recovery rates. Next, we characterize the average difference when the test measurements are erroneous (i.e., noisy). Further, we consider the case where the infection status of individuals may be dependent, which occurs when an infected person spreads the disease to another person if they are not detected and isolated by the health care provider. In addition, we consider an age of incorrect information-based error metric where the staleness metric increases linearly over time as long as the health care provider does not detect the changes in the infection status of the people. Through extensive numerical results, we observe that increasing the total test rate helps track the infection status better. In addition, an increased population size increases diversity of people with different infection and recovery rates, which may be exploited to spend testing capacity more efficiently, thereby improving the system performance. Depending on the health care provider\u2019s preferences, test rate allocation can be adjusted to detect either the infected people or the recovered people more quickly. In order to combat any errors in the test, it may be more advantageous for the health care provider to not test everyone, and instead, apply additional tests to a selected portion of the population. In the case of people with dependent infection status, as we increase the total test rate, the health care provider detects the infected people more quickly, and thus, the average time that a person stays infected decreases. Finally, the error metric needs to be chosen carefully to meet the priorities of the health care provider, as the error metric used greatly influences who will be tested and at what test rate.<\/jats:p>","DOI":"10.3390\/e24060779","type":"journal-article","created":{"date-parts":[[2022,6,1]],"date-time":"2022-06-01T03:33:18Z","timestamp":1654054398000},"page":"779","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Using Timeliness in Tracking Infections"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5122-0642","authenticated-orcid":false,"given":"Melih","family":"Bastopcu","sequence":"first","affiliation":[{"name":"Coordinated Science Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8219-8190","authenticated-orcid":false,"given":"Sennur","family":"Ulukus","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kaul, S.K., Yates, R.D., and Gruteser, M. (2012, January 25\u201330). Real-time status: How often should one update?. Proceedings of the 2012 Proceedings IEEE INFOCOM, Orlando, FL, USA.","DOI":"10.1109\/INFCOM.2012.6195689"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2637","DOI":"10.1109\/TNET.2018.2873606","article-title":"Scheduling policies for minimizing age of information in broadcast wireless networks","volume":"26","author":"Kadota","year":"2018","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Kam, C., Kompella, S., Nguyen, G.D., Wieselthier, J.E., and Ephremides, A. (2016, January 10\u201315). Age of information with a packet deadline. Proceedings of the 2016 IEEE International Symposium on Information Theory (ISIT), Barcelona, Spain.","DOI":"10.1109\/ISIT.2016.7541762"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"7492","DOI":"10.1109\/TIT.2017.2735804","article-title":"Update or wait: How to keep your data fresh","volume":"63","author":"Sun","year":"2017","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Najm, E., and Telatar, E. (2018, January 15\u201319). Status updates in a multi-stream M\/G\/1\/1 preemptive queue. Proceedings of the IEEE Infocom 2018-IEEE Conference On Computer Communications Workshops (Infocom Wkshps), Honolulu, HI, USA.","DOI":"10.1109\/INFCOMW.2018.8406928"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"7477","DOI":"10.1109\/TIT.2021.3095823","article-title":"Age of information in G\/G\/1\/1 systems: Age expressions, bounds, special cases, and optimization","volume":"67","author":"Soysal","year":"2021","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Buyukates, B., and Ulukus, S. (2020). Age of information with Gilbert-Elliot servers and samplers. arXiv.","DOI":"10.1109\/CISS48834.2020.1570627498"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"5712","DOI":"10.1109\/TIT.2020.2998100","article-title":"The age of information in networks: Moments, distributions, and sampling","volume":"66","author":"Yates","year":"2020","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Talak, R., Karaman, S., and Modiano, E. (2017, January 3\u20136). Minimizing age-of-information in multi-hop wireless networks. Proceedings of the 2017 55th Annual Allerton Conference on Communication, Control, and Computing (Allerton), Monticello, IL, USA.","DOI":"10.1109\/ALLERTON.2017.8262777"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Tripathi, V., and Moharir, S. (2017, January 4\u20138). Age of information in multi-source systems. Proceedings of the GLOBECOM 2017-2017 IEEE Global Communications Conference, Centre, Singapore.","DOI":"10.1109\/GLOCOM.2017.8254578"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1248","DOI":"10.1109\/TNET.2019.2915521","article-title":"The age of information in multihop networks","volume":"27","author":"Bedewy","year":"2019","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Zhong, J., Yates, R.D., and Soljanin, E. (2018, January 25\u201328). Multicast with prioritized delivery: How fresh is your data?. Proceedings of the 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Kalamata, Greece.","DOI":"10.1109\/SPAWC.2018.8446018"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Soysal, A., and Ulukus, S. (2018, January 28\u201331). Age of information in two-hop multicast networks. Proceedings of the 2018 52nd Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, USA.","DOI":"10.1109\/ACSSC.2018.8645440"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1109\/JCN.2019.000032","article-title":"Age of information in multihop multicast networks","volume":"21","author":"Buyukates","year":"2019","journal-title":"J. Commun. Netw."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Soysal, A., and Ulukus, S. (2019, January 3\u20136). Age of information in multicast networks with multiple update streams. Proceedings of the 2019 53rd Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, USA.","DOI":"10.1109\/IEEECONF44664.2019.9048909"},{"key":"ref_16","unstructured":"Krishnan, K.S.A., and Sharma, V. (2020, January 7\u201311). Minimizing age of information in a multihop wireless network. Proceedings of the ICC 2020-2020 IEEE International Conference on Communications, Dublin, Ireland."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1109\/JCN.2019.000038","article-title":"Fundamental bounds on the age of information in multi-hop global status update networks","volume":"21","author":"Farazi","year":"2019","journal-title":"J. Commun. Netw."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Ioannidis, S., Chaintreau, A., and Massoulie, L. (2009, January 24). Optimal and scalable distribution of content updates over a mobile social network. Proceedings of the IEEE Infocom, Rio De Janeiro, Brazil.","DOI":"10.1109\/INFCOM.2009.5062058"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wang, M., Chen, W., and Ephremides, A. (2019, January 20\u201324). Reconstruction of counting process in real-time: The freshness of information through queues. Proceedings of the ICC 2019-2019 IEEE International Conference on Communications (ICC), Shanghai, China.","DOI":"10.1109\/ICC.2019.8762021"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Sun, Y., Polyanskiy, Y., and Uysal-Biyikoglu, E. (2017, January 25\u201330). Remote estimation of the Wiener process over a channel with random delay. Proceedings of the 2017 IEEE International Symposium on Information Theory (ISIT), Aachen, Germany.","DOI":"10.1109\/ISIT.2017.8006542"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Sun, Y., and Cyr, B. (2018, January 25\u201328). Information aging through queues: A mutual information perspective. Proceedings of the 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Kalamata, Greece.","DOI":"10.1109\/SPAWC.2018.8445873"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2016","DOI":"10.1109\/TAC.2019.2926160","article-title":"Remote estimation over a packet-drop channel with Markovian state","volume":"65","author":"Chakravorty","year":"2020","journal-title":"IEEE Trans. Autom. Control"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Kam, C., Kompella, S., and Ephremides, A. (2020, January 6\u20139). Age of incorrect information for remote estimation of a binary Markov source. Proceedings of the IEEE INFOCOM 2020-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Toronto, ON, Canada.","DOI":"10.1109\/INFOCOMWKSHPS50562.2020.9162726"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"6485","DOI":"10.1109\/TCOMM.2021.3092413","article-title":"Sample, quantize and encode: Timely estimation over noisy channels","volume":"69","author":"Arafa","year":"2021","journal-title":"IEEE Trans. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2020, January 6\u20139). Who should Google Scholar update more often?. Proceedings of the IEEE INFOCOM 2020-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Toronto, ON, Canada.","DOI":"10.1109\/INFOCOMWKSHPS50562.2020.9162995"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Bacinoglu, B.T., Sun, Y., Uysal-Biyikoglu, E., and Mutlu, V. (2018, January 17\u201322). Achieving the age-energy trade-off with a finite-battery energy harvesting source. Proceedings of the 2018 IEEE International Symposium on Information Theory (ISIT), Vail, CO, USA.","DOI":"10.1109\/ISIT.2018.8437573"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Baknina, A., Ozel, O., Yang, J., Ulukus, S., and Yener, A. (2018, January 17\u201322). Sending information through status updates. Proceedings of the 2018 IEEE International Symposium on Information Theory (ISIT), Vail, CO, USA.","DOI":"10.1109\/ISIT.2018.8437496"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Baknina, A., and Ulukus, S. (2018, January 21\u201323). Coded status updates in an energy harvesting erasure channel. Proceedings of the 2018 52nd Annual Conference on Information Sciences and Systems (CISS), Princeton, NJ, USA.","DOI":"10.1109\/CISS.2018.8362277"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1109\/TGCN.2017.2778501","article-title":"Optimal status update for age of information minimization with an energy harvesting source","volume":"2","author":"Wu","year":"2018","journal-title":"IEEE Trans. Green Commun. Netw."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Feng, S., and Yang, J. (2018, January 15\u201319). Optimal status updating for an energy harvesting sensor with a noisy channel. Proceedings of the IEEE INFOCOM 2018-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Honolulu, HI, USA.","DOI":"10.1109\/INFCOMW.2018.8406974"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Feng, S., and Yang, J. (2018, January 17\u201322). Minimizing age of information for an energy harvesting source with updating failures. Proceedings of the 2018 IEEE International Symposium on Information Theory (ISIT), Vail, CO, USA.","DOI":"10.1109\/ISIT.2018.8437547"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Arafa, A., Yang, J., Ulukus, S., and Poor, H.V. (2018, January 11\u201316). Age-minimal online policies for energy harvesting sensors with incremental battery recharges. Proceedings of the 2018 Information Theory and Applications Workshop (ITA), San Diego, CA, USA.","DOI":"10.1109\/ITA.2018.8503180"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Arafa, A., Yang, J., and Ulukus, S. (2018, January 20\u201324). Age-minimal online policies for energy harvesting sensors with random battery recharges. Proceedings of the 2018 IEEE international conference on communications (ICC), Kansas City, MO, USA.","DOI":"10.1109\/ICC.2018.8422086"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"534","DOI":"10.1109\/TIT.2019.2938969","article-title":"Age-minimal transmission for energy harvesting sensors with finite batteries: Online policies","volume":"66","author":"Arafa","year":"2020","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Arafa, A., Yang, J., Ulukus, S., and Poor, H.V. (2018, January 2\u20135). Online timely status updates with erasures for energy harvesting sensors. Proceedings of the 2018 56th Annual Allerton Conference on Communication, Control, and Computing (Allerton), Monticello, IL, USA.","DOI":"10.1109\/ALLERTON.2018.8636088"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Arafa, A., Yang, J., Ulukus, S., and Poor, H.V. (2019, January 7\u201312). Using erasure feedback for online timely updating with an energy harvesting sensor. Proceedings of the 2019 IEEE International Symposium on Information Theory (ISIT), Paris, France.","DOI":"10.1109\/ISIT.2019.8849636"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1109\/TGCN.2021.3105881","article-title":"Timely status updating over erasure channels using an energy harvesting sensor: Single and multiple sources","volume":"6","author":"Arafa","year":"2022","journal-title":"IEEE Trans. Green Commun. Netw."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Farazi, S., Klein, A.G., and Brown, D.R. (2018, January 15\u201319). Average age of information for status update systems with an energy harvesting server. Proceedings of the IEEE INFOCOM 2018-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Honolulu, HI, USA.","DOI":"10.1109\/INFCOMW.2018.8406846"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1109\/TCCN.2019.2916097","article-title":"Age of information minimization for an energy harvesting cognitive radio","volume":"5","author":"Leng","year":"2019","journal-title":"IEEE Trans. Cogn. Commun. Netw."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Chen, Z., Pappas, N., Bjornson, E., and Larsson, E.G. (May, January 29). Age of information in a multiple access channel with heterogeneous traffic and an energy harvesting node. Proceedings of the IEEE INFOCOM 2019-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Paris, France.","DOI":"10.1109\/INFCOMW.2019.8845083"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1109\/TWC.2020.3025630","article-title":"Throughput maximization with an average age of information constraint in fading channels","volume":"20","author":"Bhat","year":"2021","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Ostman, J., Devassy, R., Durisi, G., and Uysal, E. (May, January 29). Peak-age violation guarantees for the transmission of short packets over fading channels. Proceedings of the IEEE INFOCOM 2019-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Paris, France.","DOI":"10.1109\/INFCOMW.2019.8845098"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2018, January 2\u20135). Age of information with soft updates. Proceedings of the 2018 56th Annual Allerton Conference on Communication, Control, and Computing (Allerton), Monticello, IL, USA.","DOI":"10.1109\/ALLERTON.2018.8635855"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1109\/JCN.2019.000034","article-title":"Minimizing age of information with soft updates","volume":"21","author":"Bastopcu","year":"2019","journal-title":"J. Commun. Netw."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Soysal, A., and Ulukus, S. (2019, January 9\u201313). Age of information scaling in large networks. Proceedings of the 2019 IEEE Global Communications Conference (GLOBECOM), Waikoloa, HI, USA.","DOI":"10.1109\/ICC.2019.8761386"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Soysal, A., and Ulukus, S. (2019, January 9\u201313). Age of information scaling in large networks with hierarchical cooperation. Proceedings of the 2019 IEEE Global Communications Conference (GLOBECOM), Waikoloa, HI, USA.","DOI":"10.1109\/GLOBECOM38437.2019.9014008"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"2413","DOI":"10.1109\/TWC.2020.3042169","article-title":"Scaling laws for age of information in wireless networks","volume":"20","author":"Buyukates","year":"2021","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Zhong, J., Yates, R.D., and Soljanin, E. (2018, January 15\u201319). Minimizing content staleness in dynamo-style replicated storage systems. Proceedings of the IEEE INFOCOM 2018-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Honolulu, HI, USA.","DOI":"10.1109\/INFCOMW.2018.8406971"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1325","DOI":"10.1109\/JSAC.2021.3065061","article-title":"Not just age but age and quality of information","volume":"39","author":"Rajaraman","year":"2021","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Liu, Z., and Ji, B. (2019, January 20\u201324). Towards the tradeoff between service performance and information freshness. Proceedings of the ICC 2019-2019 IEEE International Conference on Communications (ICC), Shanghai, China.","DOI":"10.1109\/ICC.2019.8761529"},{"key":"ref_51","unstructured":"Maatouk, A., Assaad, M., and Ephremides, A. (2020). The age of incorrect information: An enabler of semantics-empowered communication. arXiv."},{"key":"ref_52","unstructured":"Uysal, E., Kaya, O., Ephremides, A., Gross, J., Codreanu, M., Popovski, P., and Johansson, K.H. (2021). Semantic communications in networked systems. arXiv."},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Ayan, O., Vilgelm, M., Kl\u00fcgel, M., Hirche, S., and Kellerer, W. (2019, January 16\u201318). Age-of-information vs. value-of-information scheduling for cellular networked control systems. Proceedings of the 10th ACM\/IEEE International Conference on Cyber-Physical Systems, Montreal, QC, Canada.","DOI":"10.1145\/3302509.3311050"},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2021, January 24\u201326). Timely group updating. Proceedings of the 2021 55th Annual Conference on Information Sciences and Systems (CISS), Baltimore, MD, USA.","DOI":"10.1109\/CISS50987.2021.9400248"},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Banerjee, S., Bhattacharjee, R., and Sinha, A. (2020, January 21\u201326). Fundamental limits of age-of-information in stationary and non-stationary environments. Proceedings of the 2020 IEEE International Symposium on Information Theory (ISIT), Los Angeles, CA, USA.","DOI":"10.1109\/ISIT44484.2020.9174054"},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Zhong, J., and Yates, R.D. (April, January 29). Timeliness in lossless block coding. Proceedings of the 2016 Data Compression Conference (DCC), Snowbird, UT, USA.","DOI":"10.1109\/DCC.2016.113"},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Zhong, J., Yates, R.D., and Soljanin, E. (2018, January 25\u201329). Timely lossless source coding for randomly arriving symbols. Proceedings of the 2018 IEEE Information Theory Workshop (ITW), Guangzhou, China.","DOI":"10.1109\/ITW.2018.8613380"},{"key":"ref_58","doi-asserted-by":"crossref","unstructured":"Mayekar, P., Parag, P., and Tyagi, H. (2018, January 17\u201322). Optimal lossless source codes for timely updates. Proceedings of the 2018 IEEE International Symposium on Information Theory (ISIT), Vail, CO, USA.","DOI":"10.1109\/ISIT.2018.8437500"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"3714","DOI":"10.1109\/TIT.2020.2983151","article-title":"Optimal source codes for timely updates","volume":"66","author":"Mayekar","year":"2020","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_60","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., Buyukates, B., and Ulukus, S. (2020, January 18\u201320). Optimal selective encoding for timely updates. Proceedings of the 2020 54th Annual Conference on Information Sciences and Systems (CISS), Princeton, NJ, USA.","DOI":"10.1109\/CISS48834.2020.1570617397"},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Bastopcu, M., and Ulukus, S. (2020, January 21\u201326). Optimal selective encoding for timely updates with empty symbol. Proceedings of the 2020 IEEE International Symposium on Information Theory (ISIT), Los Angeles, CA, USA.","DOI":"10.1109\/ISIT44484.2020.9174312"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"5714","DOI":"10.1109\/TCOMM.2021.3059871","article-title":"Selective encoding policies for maximizing information freshness","volume":"69","author":"Bastopcu","year":"2021","journal-title":"IEEE Trans. Commun."},{"key":"ref_63","doi-asserted-by":"crossref","unstructured":"Ramirez, D., Erkip, E., and Poor, H.V. (2020, January 4\u20138). Age of information with finite horizon and partial updates. Proceedings of the ICASSP 2020-2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Barcelona, Spain.","DOI":"10.1109\/ICASSP40776.2020.9053487"},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Arafa, A., Banawan, K., Seddik, K.G., and Poor, H.V. (2019, January 9\u201313). On timely channel coding with hybrid ARQ. Proceedings of the 2019 IEEE Global Communications Conference (GLOBECOM), Big Island, HI, USA.","DOI":"10.1109\/GLOBECOM38437.2019.9013381"},{"key":"ref_65","doi-asserted-by":"crossref","unstructured":"Arafa, A., and Wesel, R.D. (2021, January 10\u201313). Timely transmissions using optimized variable length coding. Proceedings of the IEEE INFOCOM 2021-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Vancouver, BC, Canada.","DOI":"10.1109\/INFOCOMWKSHPS51825.2021.9484506"},{"key":"ref_66","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2020, January 21\u201326). Partial updates: Losing information for freshness. Proceedings of the 2020 IEEE International Symposium on Information Theory (ISIT), Los Angeles, CA, USA.","DOI":"10.1109\/ISIT44484.2020.9174078"},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"2003","DOI":"10.1109\/TVT.2018.2885871","article-title":"Average peak age-of-information minimization in UAV-assisted IoT networks","volume":"68","author":"Dhillon","year":"2019","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_68","doi-asserted-by":"crossref","unstructured":"Liu, J., Wang, X., and Dai, H. (2018, January 15\u201319). Age-optimal trajectory planning for UAV-assisted data collection. Proceedings of the IEEE INFOCOM 2018-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Honolulu, HI, USA.","DOI":"10.1109\/INFCOMW.2018.8406973"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1109\/MCOM.001.1900041","article-title":"On the role of age of information in the internet of things","volume":"57","author":"Pappas","year":"2019","journal-title":"IEEE Commun. Mag."},{"key":"ref_70","first-page":"1","article-title":"Joint information freshness and completion time optimization for vehicular networks","volume":"15","author":"Alabbasi","year":"2020","journal-title":"IEEE Trans. Serv. Comput."},{"key":"ref_71","doi-asserted-by":"crossref","unstructured":"Gao, W., Cao, G., Srivatsa, M., and Iyengar, A. (2012, January 18\u201321). Distributed maintenance of cache freshness in opportunistic mobile networks. Proceedings of the 2012 IEEE 32nd International Conference on Distributed Computing Systems, Macau, China.","DOI":"10.1109\/ICDCS.2012.63"},{"key":"ref_72","doi-asserted-by":"crossref","unstructured":"Yates, R.D., Ciblat, P., Yener, A., and Wigger, M. (2017, January 25\u201330). Age-optimal constrained cache updating. Proceedings of the 2017 IEEE International Symposium on Information Theory (ISIT), Aachen, Germany.","DOI":"10.1109\/ISIT.2017.8006506"},{"key":"ref_73","doi-asserted-by":"crossref","unstructured":"Kam, C., Kompella, S., Nguyen, G.D., Wieselthier, J.E., and Ephremides, A. (2017, January 25\u201330). Information freshness and popularity in mobile caching. Proceedings of the 2017 IEEE International Symposium on Information Theory (ISIT), Aachen, Germany.","DOI":"10.1109\/ISIT.2017.8006505"},{"key":"ref_74","doi-asserted-by":"crossref","unstructured":"Zhang, S., Li, J., Luo, H., Gao, J., Zhao, L., and Shen, X.S. (2018, January 18\u201320). Towards fresh and low-latency content delivery in vehicular networks: An edge caching aspect. Proceedings of the 2018 10th International Conference on Wireless Communications and Signal Processing (WCSP), Hangzhou, China.","DOI":"10.1109\/WCSP.2018.8555643"},{"key":"ref_75","unstructured":"Tang, H., Ciblat, P., Wang, J., Wigger, M., and Yates, R. (2020, January 15\u201319). Age of information aware cache updating with file- and age-dependent update durations. Proceedings of the 2020 18th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOPT), Volos, Greece."},{"key":"ref_76","doi-asserted-by":"crossref","unstructured":"Zhong, J., Yates, R.D., and Soljanin, E. (2018, January 17\u201322). Two freshness metrics for local cache refresh. Proceedings of the 2018 IEEE International Symposium on Information Theory (ISIT), Vail, CO, USA.","DOI":"10.1109\/ISIT.2018.8437927"},{"key":"ref_77","unstructured":"Yang, L., Zhong, Y., Zheng, F., and Jin, S. (2019). Edge caching with real-time guarantees. arXiv."},{"key":"ref_78","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2020, January 1\u20135). Maximizing information freshness in caching systems with limited cache storage capacity. Proceedings of the 2020 54th Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, USA.","DOI":"10.1109\/IEEECONF51394.2020.9443435"},{"key":"ref_79","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2021, January 24\u201326). Cache freshness in information updating systems. Proceedings of the 2021 55th Annual Conference on Information Sciences and Systems (CISS), Baltimore, MD, USA.","DOI":"10.1109\/CISS50987.2021.9400310"},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"1861","DOI":"10.1109\/TWC.2020.3037144","article-title":"Information freshness in cache updating systems","volume":"20","author":"Bastopcu","year":"2021","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_81","doi-asserted-by":"crossref","unstructured":"Kaswan, P., Bastopcu, M., and Ulukus, S. (2021, January 12\u201320). Freshness based cache updating in parallel relay networks. Proceedings of the 2021 IEEE International Symposium on Information Theory (ISIT), Melbourne, Australia.","DOI":"10.1109\/ISIT45174.2021.9518003"},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"1380","DOI":"10.1109\/JSAC.2021.3065060","article-title":"Optimizing information freshness in two-hop status update systems under a resource constraint","volume":"39","author":"Gu","year":"2021","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_83","doi-asserted-by":"crossref","unstructured":"Kuang, Q., Gong, J., Chen, X., and Ma, X. (2019). Age-of-information for computation-intensive messages in mobile edge computing. arXiv.","DOI":"10.1109\/WCSP.2019.8927944"},{"key":"ref_84","doi-asserted-by":"crossref","unstructured":"Gong, J., Kuang, Q., Chen, X., and Ma, X. (2019, January 23\u201325). Reducing age-of-information for computation-intensive messages via packet replacement. Proceedings of the 2019 11th International Conference on Wireless Communications and Signal Processing (WCSP), Xi\u2019an, China.","DOI":"10.1109\/WCSP.2019.8927943"},{"key":"ref_85","doi-asserted-by":"crossref","unstructured":"Zou, P., Ozel, O., and Subramaniam, S. (2019, January 8\u201311). Trading off computation with transmission in status update systems. Proceedings of the 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Istanbul, Turkey.","DOI":"10.1109\/PIMRC.2019.8904244"},{"key":"ref_86","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., and Ulukus, S. (2019, January 25\u201328). Age of information for updates with distortion. Proceedings of the 2019 IEEE Information Theory Workshop (ITW), Gotland, Sweden.","DOI":"10.1109\/ITW44776.2019.8988940"},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"2425","DOI":"10.1109\/TNET.2021.3091493","article-title":"Age of information for updates with distortion: Constant and age-dependent distortion constraints","volume":"29","author":"Bastopcu","year":"2021","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_88","doi-asserted-by":"crossref","unstructured":"Buyukates, B., and Ulukus, S. (2020, January 1\u20135). Timely updates in distributed computation systems with stragglers. Proceedings of the 2020 54th Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, USA.","DOI":"10.1109\/IEEECONF51394.2020.9443379"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"5273","DOI":"10.1109\/TCOMM.2020.3001873","article-title":"Timely distributed computation with stragglers","volume":"68","author":"Buyukates","year":"2020","journal-title":"IEEE Trans. Commun."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"949","DOI":"10.1109\/TNET.2021.3053937","article-title":"Optimizing information freshness through computation\u2013transmission tradeoff and queue management in edge computing","volume":"29","author":"Zou","year":"2021","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_91","doi-asserted-by":"crossref","unstructured":"Buyukates, B., and Ulukus, S. (2021, January 10\u201313). Timely communication in federated learning. Proceedings of the IEEE INFOCOM 2021-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Vancouver, BC, Canada.","DOI":"10.1109\/INFOCOMWKSHPS51825.2021.9484497"},{"key":"ref_92","doi-asserted-by":"crossref","unstructured":"Ozfatura, E., Buyukates, B., G\u00fcnd\u00fcz, D., and Ulukus, S. (2020, January 7\u201311). Age-based coded computation for bias reduction in distributed learning. Proceedings of the GLOBECOM 2020-2020 IEEE Global Communications Conference, Taipei, Taiwan.","DOI":"10.1109\/GLOBECOM42002.2020.9322412"},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"1412","DOI":"10.1109\/JSAC.2021.3065057","article-title":"A reinforcement learning approach to age of information in multi-user networks with HARQ","volume":"39","author":"Ceran","year":"2021","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_94","doi-asserted-by":"crossref","unstructured":"Yates, R.D. (2021, January 12\u201320). The age of gossip in networks. Proceedings of the 2021 IEEE International Symposium on Information Theory (ISIT), Melbourne, Australia.","DOI":"10.1109\/ISIT45174.2021.9517796"},{"key":"ref_95","doi-asserted-by":"crossref","unstructured":"Buyukates, B., Bastopcu, M., and Ulukus, S. (2021, January 27\u201330). Age of gossip in networks with community structure. Proceedings of the 2021 IEEE 22nd International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Lucca, Italy.","DOI":"10.1109\/SPAWC51858.2021.9593192"},{"key":"ref_96","doi-asserted-by":"crossref","unstructured":"Bastopcu, M., Buyukates, B., and Ulukus, S. (2021, January 7\u201311). Gossiping with binary freshness metric. Proceedings of the 2021 IEEE Globecom Workshops (GC Wkshps), Madrid, Spain.","DOI":"10.1109\/GCWkshps52748.2021.9682174"},{"key":"ref_97","doi-asserted-by":"crossref","unstructured":"Kaswan, P., and Ulukus, S. (2022). Timely gossiping with file slicing and network coding. arXiv.","DOI":"10.1109\/ISIT50566.2022.9834557"},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1561\/1300000060","article-title":"Age of information: A new concept, metric, and tool","volume":"12","author":"Kosta","year":"2017","journal-title":"Found. Trends Netw."},{"key":"ref_99","first-page":"1","article-title":"Age of information: A new metric for information freshness","volume":"12","author":"Sun","year":"2019","journal-title":"Synth. Lect. Commun. Netw."},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1109\/JSAC.2021.3065072","article-title":"Age of information: An introduction and survey","volume":"39","author":"Yates","year":"2021","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_101","doi-asserted-by":"crossref","unstructured":"Yun, J., Joo, C., and Eryilmaz, A. (2018, January 17\u201319). Optimal real-time monitoring of an information source under communication costs. Proceedings of the 2018 IEEE Conference on Decision and Control (CDC), Miami Beach, FL, USA.","DOI":"10.1109\/CDC.2018.8619768"},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"2215","DOI":"10.1109\/TNET.2020.3005549","article-title":"The age of incorrect information: A new performance metric for status updates","volume":"28","author":"Maatouk","year":"2020","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_103","unstructured":"Yates, R.D., and Goodman, D.J. (2014). Probability and Stochastic Processes, Wiley."},{"key":"ref_104","doi-asserted-by":"crossref","unstructured":"Boyd, S.P., and Vandenberghe, L. (2004). Convex Optimization, Cambridge University Press.","DOI":"10.1017\/CBO9780511804441"},{"key":"ref_105","unstructured":"Bertsekas, D.P., and Tsitsiklis, J.N. (2008). Introduction to Probability, Athena Scientific."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"3279","DOI":"10.1109\/TNSE.2020.3024723","article-title":"A time-dependent SIR model for COVID-19 with undetectable infected persons","volume":"7","author":"Chen","year":"2020","journal-title":"IEEE Trans. Netw. Sci. Eng."},{"key":"ref_107","doi-asserted-by":"crossref","unstructured":"Olmez, S.Y., Mori, J., Miehling, E., Ba\u015far, T., Smith, R.L., West, M., and Mehta, P.G. (2021, January 25\u201328). A data-informed approach for analysis, validation, and identification of COVID-19 models. Proceedings of the 2021 American Control Conference (ACC), New Orleans, LA, USA.","DOI":"10.23919\/ACC50511.2021.9483102"}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/6\/779\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:22:55Z","timestamp":1760138575000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/6\/779"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,31]]},"references-count":107,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2022,6]]}},"alternative-id":["e24060779"],"URL":"https:\/\/doi.org\/10.3390\/e24060779","relation":{},"ISSN":["1099-4300"],"issn-type":[{"value":"1099-4300","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,5,31]]}}}