{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T20:08:21Z","timestamp":1788293301066,"version":"build-2803163510"},"reference-count":31,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T00:00:00Z","timestamp":1784851200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Key Research and Development plan of Shaanxi Province","award":["No. 2024GX-ZDCYL-01-33\uff0cNo. 2024PT-ZCK-25, No. 2024CY2-GJHX-63"],"award-info":[{"award-number":["No. 2024GX-ZDCYL-01-33\uff0cNo. 2024PT-ZCK-25, No. 2024CY2-GJHX-63"]}]},{"name":"the Key Industry Innovation Chain Project of Shaanxi Province","award":["No. 2021ZDLGY07-10, No.2021ZDLNY03-08"],"award-info":[{"award-number":["No. 2021ZDLGY07-10, No.2021ZDLNY03-08"]}]},{"name":"the Science and Technology Plan Project of Shaanxi Province","award":["No.2022GY-045"],"award-info":[{"award-number":["No.2022GY-045"]}]},{"name":"the Key Industrial Chain Collaborative Innovation Project of Shaanxi Provincial Education Department","award":["No. 25JU048"],"award-info":[{"award-number":["No. 25JU048"]}]},{"name":"the Science and Technology Plan Project of Xi'an","award":["No. 22GXFW0124"],"award-info":[{"award-number":["No. 22GXFW0124"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To address the severe coverage blind spots and concurrent collision bottlenecks faced by LoRa networks in dense deployments and complex three-dimensional (3D) occlusion environments, this paper proposes a distributed cross-layer protocol framework for LoRa ad hoc networks supporting heterogeneous traffic. To break through the limitations of a single star architecture, this framework constructs a 3D penetration loss model at the physical layer and designs a distributed relay deployment algorithm based on hybrid simulated annealing, achieving blind-spot-free connectivity in complex spaces. At the MAC layer, a non-preemptive priority access mechanism based on symbol energy detection is introduced. Through differentiated backoff windows with time-domain isolation, it precisely guarantees the quality of service (QoS) requirements of heterogeneous traffic and significantly suppresses concurrent collisions. At the network layer, the CAM-AODV routing algorithm is proposed, which integrates hop count, link quality, MAC queue congestion, and nodal residual energy to achieve dynamic traffic diversion and network-wide energy balancing under bursty high loads. Simulation results demonstrate that this cross-layer framework effectively breaks the traditional network capacity bottlenecks. In a large-scale, high-density scenario with 300 nodes, CAM-AODV reduces the average end-to-end delay by 19.46% compared to the traditional AODV. Under high-concurrent loads, the packet delivery ratio (PDR) of the proposed framework improves by 16.32% over the traditional protocol, while the system delay is reduced by 13.66%. Furthermore, under the two aforementioned evaluation scenarios, the Energy Balancing Index (EBI) is significantly improved by 11.13% and 10.57%, respectively, compared to the traditional protocol. This study provides an efficient joint optimization scheme for building high-capacity, wide-coverage, and long-lifespan complex Internet of Things (IoT) networks.<\/jats:p>","DOI":"10.3390\/s26154718","type":"journal-article","created":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T08:15:56Z","timestamp":1785140156000},"page":"4718","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Cross-Layer Protocol Design and Performance Evaluation of LoRa Ad Hoc Networks for Heterogeneous Traffic"],"prefix":"10.3390","volume":"26","author":[{"given":"Shengli","family":"Pang","sequence":"first","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-8131-4543","authenticated-orcid":false,"given":"Yuanyuan","family":"Ma","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianjin","family":"Cheng","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fan","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zimiao","family":"Zou","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1494-8922","authenticated-orcid":false,"given":"Ruoyu","family":"Pan","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Honggang","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Communication and Information Engineering, Xi\u2019an University of Posts and Telecommunications, Xi\u2019an 710121, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1109\/MCOM.2017.1600613","article-title":"Understanding the limits of LoRaWAN","volume":"55","author":"Adelantado","year":"2017","journal-title":"IEEE Commun. Mag."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Pham, C., and Ehsan, M. (2021). Dense deployment of LoRa networks: Expectations and limits of channel activity detection and capture effect for radio channel access. Sensors, 21.","DOI":"10.3390\/s21030825"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Cotrim, J.R., and Kleinschmidt, J.H. (2020). LoRaWAN mesh networks: A review and classification of multihop communication. Sensors, 20.","DOI":"10.3390\/s20154273"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Garc\u00eda, L., Cancimance, C., Asorey-Cacheda, R., Z\u00fa\u00f1iga-Ca\u00f1\u00f3n, C.L., Garcia-Sanchez, A.J., and Garcia-Haro, J. (2025). Compliant and seamless hybrid (star and mesh) network topology coexistence for LoRaWAN: A proof of concept. Appl. Sci., 15.","DOI":"10.3390\/app15073487"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"22183","DOI":"10.1109\/JIOT.2024.3379568","article-title":"A decentralized dynamic relaying-based framework for enhancing LoRa networks performance","volume":"11","author":"Haif","year":"2024","journal-title":"IEEE Internet Things J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2177","DOI":"10.1109\/TIM.2018.2814082","article-title":"Monitoring of large-area IoT sensors using a LoRa wireless mesh network system: Design and evaluation","volume":"67","author":"Lee","year":"2018","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Leonardi, L., Lo Bello, L., Battaglia, F., and Patti, G. (2020). Comparative assessment of the LoRaWAN medium access control protocols for IoT: Does listen before talk perform better than ALOHA?. Electronics, 9.","DOI":"10.3390\/electronics9040553"},{"key":"ref_8","unstructured":"Mehling, N., Loh, F., and Ho\u00dffeld, T. (2024). Applicability of Listen Before Talk for LoRaWAN Deployments with Multiple Gateways. Proceedings of the 2024 15th IFIP Wireless and Mobile Networking Conference (WMNC), IEEE."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2917","DOI":"10.1109\/LWC.2024.3453788","article-title":"Hidden node probability in LoRa with listen-before-talk","volume":"13","author":"Cao","year":"2024","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Jain, A., Haque, M.A., Saifullah, A., and Zhang, H. (2024). Burst-mac: A mac protocol for handling burst traffic in LoRa network. Proceedings of the 2024 IEEE Real-Time Systems Symposium (RTSS), IEEE.","DOI":"10.1109\/RTSS62706.2024.00022"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Lundell, D., Hedberg, A., Nyberg, C., and Fitzgerald, E. (2018). A routing protocol for LoRa mesh networks. Proceedings of the 2018 IEEE 19th International Symposium on \u201cA World of Wireless, Mobile and Multimedia Networks\u201d (WoWMoM), IEEE.","DOI":"10.1109\/WoWMoM.2018.8449743"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Galzarano, S., Savaglio, C., Liotta, A., and Fortino, G. (2013, January 13\u201316). Gossiping-Based AODV for Wireless Sensor Networks. Proceedings of the 2013 IEEE International Conference on Systems, Man, and Cybernetics, Manchester, UK.","DOI":"10.1109\/SMC.2013.12"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Macaraeg, K.C.V.G., Hilario, C.A.G., and Ambatali, C.D.C. (2020). LoRa-based mesh network for off-grid emergency communications. Proceedings of the 2020 IEEE Global Humanitarian Technology Conference (GHTC), IEEE.","DOI":"10.1109\/GHTC46280.2020.9342944"},{"key":"ref_14","first-page":"907","article-title":"Cross-Layer Multi-Metric Routing Protocol Based on AODV in MANET","volume":"18","author":"Chen","year":"2020","journal-title":"J. Terahertz Sci. Electron. Inf. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Udugampola, N., Ai, X., Li, B., Gong, H., and Seneviratne, A. (2025). A Position-and Energy-Aware Routing Strategy for Subterranean LoRa Mesh Networks. Proceedings of the 2025 IEEE 50th Conference on Local Computer Networks (LCN), IEEE.","DOI":"10.1109\/LCN65610.2025.11146387"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"6501","DOI":"10.15837\/ijccc.2025.3.6501","article-title":"A Multi-Hop Routing Solution for Low Latency and Energy Efficiency in Large-Scale LoRa IoT","volume":"20","author":"Misbahuddin","year":"2025","journal-title":"Int. J. Comput. Commun. Control"},{"key":"ref_17","unstructured":"Zhou, H. (2023). Research on Routing Protocol for Large-Scale WSN Supporting Mixed Services. [Master\u2019s Thesis, Xidian University]. (In Chinese)."},{"key":"ref_18","unstructured":"Chou, S.T., Chern, H.T., and Shiao, C.M. (2010). AODV protocol with scheduling priority flow in MAC layer (AODV-SPF). Proceedings of the 6th International Conference on Networked Computing and Advanced Information Management, IEEE."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Chong, M.J.Y., Lim, S.K., Tan, K.K., and Khor, J.H. (2025). AODV-inspired Routing with Next-Hop Caching and Path Selection for LoRa Mesh Networks. Proceedings of the 2025 IEEE Industrial Electronics and Applications Conference (IEACon), IEEE.","DOI":"10.1109\/IEACon64690.2025.11254006"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Thaenthong, J., Pimsen, T., and Chidchuea, K. (2023). R-AODV: Reverse Ad-Hoc On-Demand Distance Vector Routing Algorithm With LoRa Mesh Based for Emergency Alert System. Proceedings of the 2023 15th International Conference on Information Technology and Electrical Engineering (ICITEE), IEEE.","DOI":"10.1109\/ICITEE59582.2023.10317648"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Medeiros, D.d.F., Souza, C.P.d., Carvalho, F.B.S.d., and Lopes, W.T.A. (2022). Energy-saving routing protocols for smart cities. Energies, 15.","DOI":"10.3390\/en15197382"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Scarvaglieri, A., Panebianco, A., and Busacca, F. (2024). MAGELLAN: A distributed MAB-based algorithm for Energy-Fair and Reliable Routing in Multi-Hop LoRa networks. Proceedings of the GLOBECOM 2024\u20142024 IEEE Global Communications Conference, IEEE.","DOI":"10.1109\/GLOBECOM52923.2024.10901589"},{"key":"ref_23","first-page":"157","article-title":"Intelligent Cross-Layer Routing Using Trust-Integrated Multi-Agent Actor\u2013Critic Reinforcement Learning for Hybrid IoT Systems","volume":"8","author":"Karthi","year":"2026","journal-title":"Natl. J. Antennas Propag."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Murugan, S.E.V., Balaji, T.V., Gurubaran, R., Jayapalan, B., and Vivin, A.T. (2025). LoRa-Based Smart Energy Metering and Secure Billing System for Rural Areas. Proceedings of the 2025 International Research Conference on Smart Computing and Systems Engineering (SCSE), IEEE.","DOI":"10.1109\/SCSE65633.2025.11031068"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Ryan, S.Y.H., Xiang, L.J., Wee, E.T.S., Yiang, L.K., Yu, S.L.Q., and Abbas, M.F.B. (2024). A Study of Scalable Mesh Algorithms for Large-scale Aquaculture using LoRa. Proceedings of the 2024 IEEE VTS Asia Pacific Wireless Communications Symposium (APWCS), IEEE.","DOI":"10.1109\/APWCS61586.2024.10679328"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Do Huy, N., Thanh, T.P., Trong, T.H., Viet, H.D., and Huu, P.N. (2025). Design and Deployment of Mobile Air Quality Monitoring System Using Node-RED and MQTT. Proceedings of the 2025 IEEE Workshop on Signal Processing Systems (SiPS), IEEE.","DOI":"10.1109\/SiPS66314.2025.11261304"},{"key":"ref_27","first-page":"19","article-title":"Radio coverage in buildings","volume":"8","author":"Keenan","year":"1990","journal-title":"Br. Telecom Technol. J."},{"key":"ref_28","unstructured":"(2023). Recommendation ITU-R P.2109-2: Prediction of Building Entry Loss (Standard No. ITU-R P.2109-2)."},{"key":"ref_29","unstructured":"Semtech Corporation (2020). SX1276\/77\/78\/79: 137 MHz to 1020 MHz Low Power Long Range Transceiver Data Sheet, Semtech Corporation."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Miras, C., Austria, I., and Ong, D. (2022). Self-organizing multi-hop LoRa mesh network for wide area air quality monitoring. Proceedings of the TENCON 2022\u20142022 IEEE Region 10 Conference (TENCON), IEEE.","DOI":"10.1109\/TENCON55691.2022.9977930"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Ihsan, M., and Sharma, R. (2025). Scalable and Energy-Efficient AODV Routing Using Cross-Layer Design for Flying Ad Hoc Networks. Proceedings of the 2025 International Conference on Next Generation of Green Information and Emerging Technologies (GIET), IEEE.","DOI":"10.1109\/GIET65294.2025.11234862"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/15\/4718\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T04:25:59Z","timestamp":1785299159000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/15\/4718"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,24]]},"references-count":31,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["s26154718"],"URL":"https:\/\/doi.org\/10.3390\/s26154718","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,24]]}}}