{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,13]],"date-time":"2026-04-13T15:58:13Z","timestamp":1776095893840,"version":"3.50.1"},"reference-count":32,"publisher":"Association for Computing Machinery (ACM)","issue":"3","funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62272237, and 62372249"],"award-info":[{"award-number":["62272237, and 62372249"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["dl.acm.org"],"crossmark-restriction":true},"short-container-title":["ACM Trans. Sen. Netw."],"published-print":{"date-parts":[[2026,5,30]]},"abstract":"<jats:p>Radio Frequency (RF) has been widely studied, but multiple rechargeable devices may block each other, causing the mutual interference and reducing the charging utility. In recent years, pendant charging has been proposed. In pendant charging, the charger is suspended vertically downward, and the rechargeable devices are placed on the ground, thus avoiding the mutual interference. However, the existing studies only consider the pendant charging with fixed heights, where the usability is limited. In this article, we study the height-adjustable directional pendant wireless charging system, where the directional wireless chargers are suspended vertically, and the charging ranges and received powers can be changed by adjusting the heights of chargers. We formulate the Utility Maximization Height-adjustable charging Scheduling (UMHS) problem to maximize the total utility of the wireless charging system. We first propose a height discretization method to reduce the search space significantly and obtain a discretized problem with approximation ratio to the UMHS problem. Then, we transform the discretized problem into an equivalent Multi-Dimensional Knapsack Problem (MDKP). Finally, an approximation algorithm for UMHS is proposed through the height discretization and the approximation algorithm for MDKP. The results show that our algorithm can increase up to 24.41% and 18.67% total utility compared with benchmark algorithms in extensive simulations and field experiments, respectively.<\/jats:p>","DOI":"10.1145\/3798102","type":"journal-article","created":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T21:01:07Z","timestamp":1773867667000},"page":"1-23","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Maximizing Charging Utility for Height-adjustable Directional Pendant Wireless Chargers"],"prefix":"10.1145","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9320-3672","authenticated-orcid":false,"given":"Sixu","family":"Wu","sequence":"first","affiliation":[{"name":"Nanjing University of Posts and Telecommunications","place":["Nanjing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7868-5471","authenticated-orcid":false,"given":"Yun","family":"Yang","sequence":"additional","affiliation":[{"name":"Swinburne University of Technology","place":["Melbourne, Australia"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0545-8187","authenticated-orcid":false,"given":"Haipeng","family":"Dai","sequence":"additional","affiliation":[{"name":"Nanjing University","place":["Nanjing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0824-6203","authenticated-orcid":false,"given":"Linfeng","family":"Liu","sequence":"additional","affiliation":[{"name":"Nanjing University of Posts and Telecommunications","place":["Nanjing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5796-5071","authenticated-orcid":false,"given":"Lijie","family":"Xu","sequence":"additional","affiliation":[{"name":"Nanjing University of Posts and Telecommunications","place":["Nanjing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0523-9673","authenticated-orcid":false,"given":"Jia","family":"Xu","sequence":"additional","affiliation":[{"name":"Nanjing University of Posts and Telecommunications","place":["Nanjing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"320","published-online":{"date-parts":[[2026,4,13]]},"reference":[{"key":"e_1_3_1_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-6377(02)00222-5"},{"key":"e_1_3_1_3_2","doi-asserted-by":"publisher","DOI":"10.1145\/3278721.3278757"},{"key":"e_1_3_1_4_2","doi-asserted-by":"publisher","DOI":"10.1109\/TNET.2017.2750323"},{"key":"e_1_3_1_5_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMC.2023.3338563"},{"key":"e_1_3_1_6_2","doi-asserted-by":"publisher","DOI":"10.2307\/3689476"},{"key":"e_1_3_1_7_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMC.2023.3255980"},{"key":"e_1_3_1_8_2","doi-asserted-by":"publisher","DOI":"10.1109\/INFOCOM48880.2022.9796770"},{"key":"e_1_3_1_9_2","doi-asserted-by":"publisher","DOI":"10.1109\/ITNEC56291.2023.10082297"},{"key":"e_1_3_1_10_2","doi-asserted-by":"publisher","DOI":"10.1109\/SAHCN.2019.8824816"},{"key":"e_1_3_1_11_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMC.2022.3216817"},{"key":"e_1_3_1_12_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMC.2021.3137308"},{"key":"e_1_3_1_13_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMC.2024.3398026"},{"key":"e_1_3_1_14_2","doi-asserted-by":"publisher","DOI":"10.1109\/TNET.2021.3095280"},{"key":"e_1_3_1_15_2","doi-asserted-by":"publisher","DOI":"10.1109\/COMST.2015.2499783"},{"key":"e_1_3_1_16_2","volume-title":"CoolTerm","author":"Meier Roger","year":"2025","unstructured":"Roger Meier. 2025. 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