{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,22]],"date-time":"2025-10-22T05:16:55Z","timestamp":1761110215577,"version":"build-2065373602"},"reference-count":18,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2016,9,22]],"date-time":"2016-09-22T00:00:00Z","timestamp":1474502400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004663","name":"Ministry of Science and Technology, Taiwan","doi-asserted-by":"publisher","award":["104-2221-E-006-041-","104-3115-E-009-006-"],"award-info":[{"award-number":["104-2221-E-006-041-","104-3115-E-009-006-"]}],"id":[{"id":"10.13039\/501100004663","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Message Queuing Telemetry Transport for Sensor Networks (MQTT-SN) and Constrained Application Protocol (CoAP) are two protocols supporting publish\/subscribe models for IoT devices to publish messages to interested subscribers. Retransmission mechanisms are introduced to compensate for the lack of data reliability. If the device does not receive the acknowledgement (ACK) before retransmission timeout (RTO) expires, the device will retransmit data. Setting an appropriate RTO is important because the delay may be large or retransmission may be too frequent when the RTO is inappropriate. We propose a Gateway-assisted CoAP (GaCoAP) to dynamically compute RTO for devices. Simulation models are proposed to investigate the performance of GaCoAP compared with four other methods. The experiment results show that GaCoAP is more suitable for IoT devices.<\/jats:p>","DOI":"10.3390\/s16101560","type":"journal-article","created":{"date-parts":[[2016,9,22]],"date-time":"2016-09-22T09:59:55Z","timestamp":1474538395000},"page":"1560","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Gateway-Assisted Retransmission for Lightweight and Reliable IoT Communications"],"prefix":"10.3390","volume":"16","author":[{"given":"Hui-Ling","family":"Chang","sequence":"first","affiliation":[{"name":"Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cheng-Gang","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mong-Ting","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7549-5245","authenticated-orcid":false,"given":"Meng-Hsun","family":"Tsai","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chia-Ying","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan 701, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,9,22]]},"reference":[{"key":"ref_1","unstructured":"ETSI 3GPP TR22.988v12.2.0, Study on Alternatives to E.164 for Machine-Type Communications (MTC), 2012, 3GPP SA1. 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Available online: http:\/\/mqtt.org\/new\/wp-content\/uploads\/2009\/06\/MQTT-SN_spec_v1.2.pdf."},{"key":"ref_5","unstructured":"Shelby, Z., Hartke, K., and Bormann, C. The Constrained Application Protocol (CoAP) (RFC 7252). Available online: https:\/\/tools.ietf.org\/html\/rfc7252."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3846","DOI":"10.1109\/JSEN.2013.2263379","article-title":"Towards the Implementation of IoT for Environmental Condition Monitoring in Homes","volume":"13","author":"Kelly","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_7","unstructured":"MQTT. Available online: http:\/\/mqtt.org\/."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Paxson, M.A.V., Chu, J., and Sargent, M. Computing TCP\u2019s Retransmission Timer (RFC 6298), 2011. 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