{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:02:11Z","timestamp":1760241731736,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2018,7,23]],"date-time":"2018-07-23T00:00:00Z","timestamp":1532304000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Wireless power transfer (WPT) is a promising technology to realize the vision of Internet-of-Things (IoT) by powering energy-hungry IoT nodes by electromagnetic waves, overcoming the difficulty in battery recharging for massive numbers of nodes. Specifically, wireless charging stations (WCS) are deployed to transfer energy wirelessly to IoT nodes in the charging coverage. However, the coverage is restricted due to the limited hardware capability and safety issue, making mobile nodes have different battery charging patterns depending on their moving speeds. For example, slow moving nodes outside the coverage resort to waiting for energy charging from WCSs for a long time while those inside the coverage consistently recharge their batteries. On the other hand, fast moving nodes are able to receive energy within a relatively short waiting time. This paper investigates the above impact of node speed on energy provision and the resultant throughput of energy-constrained opportunistic IoT networks when data exchange between nodes are constrained by their intermittent connections as well as the levels of remaining energy. To this end, we design a two-dimensional Markov chain of which the state dimensions represent remaining energy and distance to the nearest WCS normalized by node speed, respectively. Solving this enables providing the following three insights. First, faster node speed makes the inter-meeting time between a node and a WCS shorter, leading to more frequent energy supply and higher throughput. Second, the above effect of node speed becomes marginal as the battery capacity increases. Finally, as nodes are more densely deployed, the throughput becomes scaling with the density ratio between mobiles and WCSs but independent of node speed, meaning that the throughput improvement from node speed disappears in dense networks. The results provide useful guidelines for IoT network provisioning and planning to achieve the maximum throughput performance given mobile environments.<\/jats:p>","DOI":"10.3390\/s18072398","type":"journal-article","created":{"date-parts":[[2018,7,24]],"date-time":"2018-07-24T02:58:56Z","timestamp":1532401136000},"page":"2398","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Impact of Node Speed on Energy-Constrained Opportunistic Internet-of-Things with Wireless Power Transfer"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8592-7408","authenticated-orcid":false,"given":"Seung-Woo","family":"Ko","sequence":"first","affiliation":[{"name":"Department of Electrical and Electronic Engineering, The University of Hong Kong, Pok Fu Lam, Hong Kong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5228-9913","authenticated-orcid":false,"given":"Seong-Lyun","family":"Kim","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 03722, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,7,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1109\/JIOT.2014.2306328","article-title":"Internet of Things for Smart Cities","volume":"1","author":"Zanella","year":"2014","journal-title":"IEEE Inter. Things J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1109\/MAP.2013.6529362","article-title":"Wireless power transfer for mobile applications and health effect","volume":"55","author":"Lin","year":"2013","journal-title":"IEEE Antennas Propag. Mag."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1109\/MCOM.2015.7120022","article-title":"Cutting the last wires for mobile communications by microwave power transfer","volume":"53","author":"Huang","year":"2015","journal-title":"IEEE Commun. Mag."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1531","DOI":"10.1016\/j.jnca.2012.12.028","article-title":"Opportunistic IoT: Exploring the harmonious interaction between human and the internet of things","volume":"36","author":"Guo","year":"2013","journal-title":"J. Netw. Comput. Appl."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1109\/MCOM.2014.6710070","article-title":"From \u201csmart objects\u201d to \u201csocial objects\u201d: The next evolutionary step of the internet of things","volume":"52","author":"Atzori","year":"2014","journal-title":"IEEE Commun. Mag."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Tran, H.V., and Kaddoum, G. (2018, January 16\u201318). Green Cell-less Design for RF-Wireless Power Transfer Networks. Proceedings of the Wireless Communications and Networking Conference (WCNC), Barcelona, Spain.","DOI":"10.1109\/WCNC.2018.8377105"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1109\/MPOT.2017.2749118","article-title":"RF wireless power transfer: Regreening future networks","volume":"2","author":"Tran","year":"2018","journal-title":"IEEE Potential"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2264","DOI":"10.1109\/TCOMM.2017.2676103","article-title":"Communications and signal design for wireless power transmission","volume":"65","author":"Zeng","year":"2017","journal-title":"IEEE Trans. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1126\/science.1143254","article-title":"Wireless power transfer via strongly coupled magnetic resonances","volume":"317","author":"Kurs","year":"2007","journal-title":"Science"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"544","DOI":"10.1109\/TIE.2010.2046002","article-title":"Analysis, experimental results, and range adaption of magnetically coupled resonators for wireless power transfer","volume":"58","author":"Sample","year":"2011","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"582","DOI":"10.1109\/TMTT.2016.2618921","article-title":"Impedance Matching in Wireless Power Transfer","volume":"65","author":"Huang","year":"2017","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1175","DOI":"10.1109\/TCSI.2013.2246252","article-title":"Near Field Resonator Isolation System: Theory to Implementation","volume":"60","author":"Kim","year":"2013","journal-title":"IEEE Trans. Circuits Syst. I Reg. Pap."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"902","DOI":"10.1109\/TWC.2013.122313.130727","article-title":"Enabling Wireless Power Transfer in Cellular Networks: Architecture, Modeling and Deployment","volume":"13","author":"Huang","year":"2014","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3111","DOI":"10.1109\/TWC.2018.2806967","article-title":"Inference from randomized transmissions by many backscatter sensors","volume":"17","author":"Zhu","year":"2018","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1258","DOI":"10.3390\/s17061258","article-title":"Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks","volume":"17","author":"Lyu","year":"2017","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"5539","DOI":"10.1109\/TWC.2015.2439673","article-title":"Full-Duplex Wireless-Powered Communication Network With Energy Causality","volume":"14","author":"Kang","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_17","unstructured":"Tran, H.-V., Kaddoum, G., and Shin, O. (2018). Joint Channel Resources Allocation and Beamforming in Energy Harvesting Systems. IEEE Wirel. Commun. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Clerckx, B., Bayhuzina, E., Yates, D., and Mitcheson, P.D. (2015, January 25\u201328). Waveform Optimization for wireless power transfer with nonlinear energy harvester modeling. Proceedings of the 2015 International Symposium on Wireless Communication Systems (ISWCS), Brussels, Belgium.","DOI":"10.1109\/ISWCS.2015.7454345"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tran, H.-V., Kaddoum, G., and Truong, K.T. (arXiv, 2018). Resource allocation in SWIPT networks under a non-linear energy harvesting model: Power efficiency, user fairness, and channel non-reciprocity, arXiv.","DOI":"10.1109\/TVT.2018.2848963"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2207","DOI":"10.1109\/LAWP.2017.2706944","article-title":"A low-complexity adaptive multisine waveform design for wireless power transfer","volume":"16","author":"Clerckx","year":"2017","journal-title":"IEEE Antennas Wirel. Propag. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1748","DOI":"10.1109\/TNET.2012.2185831","article-title":"Making sensor networks immoral: An energy-renewal approach with wireless power transfer","volume":"20","author":"Xie","year":"2012","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1109\/TVT.2015.2391119","article-title":"Optimal charging in wireless rechargeable sensor networks","volume":"65","author":"Fu","year":"2016","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_23","first-page":"3531","article-title":"Safe charging for wireless power transfer","volume":"25","author":"Dai","year":"2017","journal-title":"Proc. IEEE"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"7400","DOI":"10.1109\/TVT.2017.2668990","article-title":"Mobile Charging in Wireless-Powered Sensor Networks: Optimal Scheduling and Experimental Implementation","volume":"66","author":"Sangare","year":"2017","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.comnet.2015.01.018","article-title":"Distributed wireless power transfer in sensor networks with multiple mobile chargers","volume":"80","author":"Madhja","year":"2015","journal-title":"Comput. Netw."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Li, K., Luan, H., and Shen, C.-C. (2012, January 14). Qi-Ferry: Energy-constrained wireless charging in wireless sensor networks. Proceedings of the 2012 IEEE Wireless Communications and Networking Conference (WCNC), Paris, France.","DOI":"10.1109\/WCNC.2012.6214221"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1931","DOI":"10.1109\/TMC.2012.161","article-title":"Energy provisioning in wireless rechargeable sensor networks","volume":"12","author":"He","year":"2013","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"7597","DOI":"10.1109\/TIT.2013.2276811","article-title":"Spatial throughput of mobile ad hoc network with energy harvesting","volume":"59","author":"Huang","year":"2013","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3740","DOI":"10.1109\/TVT.2014.2357833","article-title":"Cooperation in delay tolerant networks with wireless energy transfer: Performance analysis and optimization","volume":"64","author":"Niyato","year":"2015","journal-title":"IEEE Trans. Veh. Tecnnol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1870","DOI":"10.1109\/TVT.2013.2285922","article-title":"Delay-limited communications on mobile node with wireless energy harvesting: Performance analysis and optimization","volume":"63","author":"Niyato","year":"2014","journal-title":"IEEE Trans. Veh. Tecnnol."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Kim, J., Park, J., Ko, S.-W., and Kim, S.-L. (2016, January 9\u201313). User attraction via wireless charging in downlink cellular networks. Proceedings of the 2016 14th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), Tempe, AZ, USA.","DOI":"10.1109\/WIOPT.2016.7492901"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"527","DOI":"10.1109\/TPDS.2014.2310484","article-title":"Quality of energy provisioning for wireless power transfer","volume":"26","author":"Dai","year":"2015","journal-title":"IEEE Trans. Parallel Distrib. Syst."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1109\/LCOMM.2013.020413.122729","article-title":"The capacity of energy-constrained mobile networks with wireless power transfer","volume":"17","author":"Ko","year":"2013","journal-title":"IEEE Commun. Lett."},{"key":"ref_34","first-page":"2","article-title":"NB-IoT: A sustainable technology for connecting billions of devices","volume":"4","author":"Westerberg","year":"2016","journal-title":"Ericsson Technol. Rev."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1109\/TNET.2002.801403","article-title":"Mobility increases the capacity of ad hoc wireless networks","volume":"10","author":"Grossglauser","year":"2012","journal-title":"IEEE\/ACM Trans. Netw."},{"key":"ref_36","unstructured":"Kesler, M. (2013). Highly Resonant Wireless Power Transfer: Safe, Efficient, and Over Distance, Witricity."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1819","DOI":"10.1109\/TPEL.2009.2017195","article-title":"Magnetic resonant coupling as a potential means for wireless power transfer to multiple small receivers","volume":"27","author":"Cannon","year":"2009","journal-title":"IEEE Trans. Power Electron."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"801","DOI":"10.1109\/TMTT.2015.2398422","article-title":"Efficiency and optimal loads analysis for multiple-receiver wireless power transfer systems","volume":"63","author":"Fu","year":"2015","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Xie, L., Shi, Y., Hou, Y.T., Sherali, H.D., and Midkiff, S.F. (2012, January 18\u201321). On renewable sensor networks with wireless energy transfer: The multi-node case. Proceedings of the 2012 9th annual IEEE communications society conference on Sensor, mesh and ad hoc communications and networks (SECON), Seoul, Korea.","DOI":"10.1109\/SECON.2012.6275766"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"044102-1","DOI":"10.1063\/1.3284651","article-title":"Simultaneous mid-range power transfer to multiple devices","volume":"96","author":"Kurs","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1109\/MWC.2016.7422410","article-title":"Traffic convexity aware cellular networks: A vehicular heavy user perspective","volume":"23","author":"Shim","year":"2016","journal-title":"IEEE Wirel. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Meyer, C.D. (2000). Matrix Analysis and Applied Linear Algebra, Society for Industrial and Applied Mathematics.","DOI":"10.1137\/1.9780898719512"},{"key":"ref_43","unstructured":"Akar, N., and Sohraby, K. (1997, January 5\u20137). Finite and infinite QBD chains: A simple and unifying algorithm approach. Proceedings of the 1997 IEEE International Performance, Computing and Communications Conference, Scottsdale\/Phoenix, AZ, USA."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1007\/BF01721131","article-title":"A general class of Markov process with explicit matrix-geometric solutions","volume":"9","author":"Ramswami","year":"1986","journal-title":"Oper. Res. Spektrum"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/7\/2398\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:13:53Z","timestamp":1760195633000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/7\/2398"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,7,23]]},"references-count":44,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2018,7]]}},"alternative-id":["s18072398"],"URL":"https:\/\/doi.org\/10.3390\/s18072398","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2018,7,23]]}}}