{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T06:02:08Z","timestamp":1783749728562,"version":"3.55.0"},"reference-count":51,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2021,5,12]],"date-time":"2021-05-12T00:00:00Z","timestamp":1620777600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Cisco Unversity Research","award":["2019-199458(3696)"],"award-info":[{"award-number":["2019-199458(3696)"]}]},{"name":"ANID Basal Project","award":["FB0008"],"award-info":[{"award-number":["FB0008"]}]},{"name":"CONICYT Chile-PFCHA\/Mag\u00edster Nacional","award":["2020-2220024"],"award-info":[{"award-number":["2020-2220024"]}]},{"name":"CONICYT Chile-PFCHA\/Doctorado 524 Nacional","award":["2020-21201428"],"award-info":[{"award-number":["2020-21201428"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the face of cooperative intelligent transportation systems (C-ITS) advancements, the inclusion of vulnerable road users (VRU), i.e., pedestrians, cyclists, and motorcyclists, has just recently become a part of the discussion. Including VRU in C-ITS presents new challenges, most notably the trade-off between the increase in VRU safety and the aggravation in channel congestion resulting from VRU-generated messages. However, previous studies mainly focus on network-related metrics without giving much consideration to VRU safety-related metrics. In this context, we evaluated such a trade-off with a study of motion-based message generation rules for VRU transmissions. The rules were analyzed using theoretical and simulation-based evaluations. In addition to studying the message generation rules using channel load metrics, such as channel busy ratio (CBR) and packet delivery ratio (PDR), we introduced a new metric: the VRU Awareness Probability (VAP). VAP uses the exchange of messages from active VRU to measure the probability of VRU detection by nearby vehicles. Results show that fixed message-filtering mechanisms reduce the overall channel load, but they could negatively impact VRU detection. We established the importance of quantifying the VRU awareness and its inclusion in C-ITS analysis because of its direct impact on VRU safety. We also discussed approaches that include VRU context and dynamism to improve the definition of message generation rules.<\/jats:p>","DOI":"10.3390\/s21103375","type":"journal-article","created":{"date-parts":[[2021,5,12]],"date-time":"2021-05-12T22:46:14Z","timestamp":1620859574000},"page":"3375","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Impact of Safety Message Generation Rules on the Awareness of Vulnerable Road Users"],"prefix":"10.3390","volume":"21","author":[{"given":"Tom\u00e1s","family":"Lara","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, Universidad de Chile, Santiago 8370451, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6987-8856","authenticated-orcid":false,"given":"Alexis","family":"Y\u00e1\u00f1ez","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Universidad de Chile, Santiago 8370451, Chile"},{"name":"School of Industrial Engineer, Universidad Santo Tom\u00e1s, Santiago 8370003, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1686-2644","authenticated-orcid":false,"given":"Sandra","family":"C\u00e9spedes","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Universidad de Chile, Santiago 8370451, Chile"},{"name":"NIC Chile Research Labs, Universidad de Chile, Santiago 8370456, Chile"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8597-7344","authenticated-orcid":false,"given":"Abdelhakim Senhaji","family":"Hafid","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Operational Research, University of Montreal, Montreal, QC H3T IJ4, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"584","DOI":"10.1109\/SURV.2011.061411.00019","article-title":"Vehicular networking: A survey and tutorial on requirements, architectures, challenges, standards and solutions","volume":"13","author":"Karagiannis","year":"2011","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1109\/MVT.2009.935536","article-title":"Car-2-x and pedestrian safety","volume":"5","author":"David","year":"2010","journal-title":"IEEE VEhicular Technol. Mag."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Anaya, J.J., Merdrignac, P., Shagdar, O., Nashashibi, F., and Naranjo, J.E. (2014, January 8\u201311). Vehicle to pedestrian communications for protection of vulnerable road users. Proceedings of the 2014 IEEE Intelligent Vehicles Symposium Proceedings, Dearborn, MI, USA.","DOI":"10.1109\/IVS.2014.6856553"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Rostami, A., Cheng, B., Lu, H., Kenney, J.B., and Gruteser, M. (2016, January 3\u20137). Performance and channel load evaluation for contextual pedestrian-to-vehicle transmissions. Proceedings of the First ACM International Workshop on Smart, Autonomous, and Connected Vehicular Systems and Services, New York, NY, USA.","DOI":"10.1145\/2980100.2980103"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Sewalkar, P., Krug, S., and Seitz, J. (2017, January 6\u20138). Towards 802.11 p-based vehicle-to-pedestrian communication for crash prevention systems. Proceedings of the 2017 9th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), Munich, Germany.","DOI":"10.1109\/ICUMT.2017.8255154"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s12544-017-0230-3","article-title":"Integration of vulnerable road users in cooperative ITS systems","volume":"9","author":"Scholliers","year":"2017","journal-title":"Eur. Transp. Res. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Casademont, J., Calveras, A., Qui\u00f1ones, D., Navarro, M., Arribas, J., and Catalan-Cid, M. (2019, January 26\u201328). Cooperative-Intelligent Transport Systems for Vulnerable Road Users Safety. Proceedings of the 2019 7th International Conference on Future Internet of Things and Cloud (FiCloud), Istanbul, Turkey.","DOI":"10.1109\/FiCloud.2019.00027"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Rufino, J., Silva, L., Fernandes, B., Almeida, J., and Ferreira, J. (2018, January 9\u201313). Empowering Vulnerable Road Users in C-ITS. Proceedings of the 2018 IEEE Globecom Workshops (GC Wkshps), Abu Dhabi, United Arab Emirates.","DOI":"10.1109\/GLOCOMW.2018.8644266"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1049\/iet-its.2016.0024","article-title":"Quantifying the effectiveness of ITS in improving safety of VRUs","volume":"11","author":"Silla","year":"2017","journal-title":"IET Intell. Transp. Syst."},{"key":"ref_10","unstructured":"ETSI (2019). Intelligent Transport Systems (ITS); Vulnerable Road Users (VRU) awareness; Part 1: Use Cases Definition; Release 2, European Telecommunications Standards Institute (ETSI). Version 2.1.1."},{"key":"ref_11","unstructured":"World Health Organization (2018). Global Status Report on Road Safety 2018, World Health Organization."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4564","DOI":"10.1109\/TVT.2016.2598786","article-title":"Wisafe: Wi-fi pedestrian collision avoidance system","volume":"66","author":"Ho","year":"2016","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2086","DOI":"10.1109\/TITS.2017.2743709","article-title":"Three-phases smartphone-based warning system to protect vulnerable road users under fuzzy conditions","volume":"19","author":"Zadeh","year":"2017","journal-title":"IEEE Trans. Intell. Transp. Syst."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Anaya, J.J., Talavera, E., Gim\u00e9nez, D., G\u00f3mez, N., Felipe, J., and Naranjo, J.E. (2015, January 15\u201318). Vulnerable road users detection using V2X communications. Proceedings of the 2015 IEEE 18th International Conference on Intelligent Transportation Systems, Gran Canaria, Spain.","DOI":"10.1109\/ITSC.2015.26"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Al-Lawati, A., Al-Jahdhami, S., Al-Belushi, A., Al-Adawi, D., Awadalla, M., and Al-Abri, D. (2015, January 1\u20134). RFID-based system for school children transportation safety enhancement. Proceedings of the 2015 IEEE 8th GCC Conference & Exhibition, Muscat, Oman.","DOI":"10.1109\/IEEEGCC.2015.7060047"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Sewalkar, P., and Seitz, J. (2019). Vehicle-to-pedestrian communication for vulnerable road users: Survey, design considerations, and challenges. Sensors, 19.","DOI":"10.3390\/s19020358"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Thandavarayan, G., Sepulcre, M., and Gozalvez, J. (2019, January 9\u201312). Analysis of Message Generation Rules for Collective Perception in Connected and Automated Driving. Proceedings of the 2019 IEEE Intelligent Vehicles Symposium (IV), Paris, France.","DOI":"10.1109\/IVS.2019.8813806"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Garlichs, K., G\u00fcnther, H.J., and Wolf, L.C. (2019, January 4\u20136). Generation Rules for the Collective Perception Service. Proceedings of the IEEE Vehicular Networking Conference (VNC), Los Angeles, CA, USA.","DOI":"10.1109\/VNC48660.2019.9062827"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wu, X., Miucic, R., Yang, S., Al-Stouhi, S., Misener, J., Bai, S., and Chan, W.h. (2014, January 14\u201317). Cars talk to phones: A DSRC based vehicle-pedestrian safety system. Proceedings of the 2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall), Vancouver, BC, Canada.","DOI":"10.1109\/VTCFall.2014.6965898"},{"key":"ref_20","unstructured":"(2020, February 28). FCC Modernizes 5.9 GHz Band to Improve Wi-Fi and Automotive Safety, Available online: https:\/\/www.fcc.gov\/document\/fcc-modernizes-59-ghz-band-improve-wi-fi-and-automotive-safety."},{"key":"ref_21","unstructured":"European Telecommunications Standards Institute Intelligent Tranportation Systems (ETSI ITS) (2019). Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of Applications; Part 2: Specification of Cooperative Awareness Basic Service, European Telecommunications Standards Institute (ETSI)."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1845","DOI":"10.1007\/s11277-015-3160-1","article-title":"An energy efficient vehicle to pedestrian communication method for safety applications","volume":"86","author":"Lee","year":"2016","journal-title":"Wirel. Pers. Commun."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1109\/MITS.2016.2573338","article-title":"Cloud-based pedestrian road-safety with situation-adaptive energy-efficient communication","volume":"8","author":"Bagheri","year":"2016","journal-title":"IEEE Intell. Transp. Syst. Mag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1162","DOI":"10.1109\/JPROC.2011.2132790","article-title":"Dedicated Short-Range Communications (DSRC) Standards in the United States","volume":"99","author":"Kenney","year":"2011","journal-title":"Proc. IEEE"},{"key":"ref_25","unstructured":"3rd Generation Partnership Project (3GPP) (2021, May 10). Technical Specification Group Services and System Aspects; Release 14 Description; Summary of Rel-14 Work Items (Release 14). Available online: https:\/\/portal.3gpp.org\/desktopmodules\/Specifications\/SpecificationDetails.aspx?specificationId=2934."},{"key":"ref_26","unstructured":"3rd Generation Partnership Project (3GPP) (2021, May 10). Technical Specification Group Services and System Aspects; Release 15 Description; Summary of Rel-15 Work Items (Release 15). Available online: https:\/\/portal.3gpp.org\/desktopmodules\/Specifications\/SpecificationDetails.aspx?specificationId=3389."},{"key":"ref_27","unstructured":"3rd Generation Partnership Project (3GPP) (2021, May 10). Technical Specification Group Services and System Aspects; Enhancement of 3GPP support for V2X scenarios; Stage 1 (Release 15). Available online: https:\/\/portal.3gpp.org\/desktopmodules\/Specifications\/SpecificationDetails.aspx?specificationId=3180."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Zheng, K., Zhang, L., Xiang, W., and Wang, W. (2016). Heterogeneous Vehicular Networks, Springer.","DOI":"10.1007\/978-3-319-25622-1"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"858","DOI":"10.1109\/TVT.2020.3046413","article-title":"Automated Decision System to Exploit Network Diversity for Connected Vehicles","volume":"70","author":"Valle","year":"2020","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3882","DOI":"10.1109\/TVT.2011.2162755","article-title":"Performance analysis of the IEEE 802.11 MAC protocol for DSRC safety applications","volume":"60","author":"Hassan","year":"2011","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3904","DOI":"10.1109\/TVT.2016.2544935","article-title":"Exploring the practical limits of cooperative awareness in vehicular communications","volume":"65","author":"Boban","year":"2016","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Y\u00e1\u00f1ez, A., and C\u00e9spedes, S. (2020, January 16\u201318). Pedestrians also Have Something to Say: Integration of Connected VRU in Bidirectional Simulations. Proceedings of the 2020 IEEE Vehicular Networking Conference (VNC), New York, NY, USA.","DOI":"10.1109\/VNC51378.2020.9318367"},{"key":"ref_33","first-page":"60","article-title":"Towards a Bidirectional Coupling of Pedestrian Dynamics and Mobile Communication Simulation","volume":"Volume 66","author":"Wischhof","year":"2019","journal-title":"Proceedings of the 6th International OMNeT++ Community Summit 2019"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"43","DOI":"10.29007\/1zt5","article-title":"Monaco SUMO Traffic (MoST) Scenario: A 3D Mobility Scenario for Cooperative ITS","volume":"2","author":"Codeca","year":"2018","journal-title":"EPiC Ser. Eng."},{"key":"ref_35","unstructured":"Behrisch, M., Bieker, L., Erdmann, J., Knocke, M., Krajzewicz, D., and Wagner, P. (2014). Evolution of SUMO\u2019s Simulation Model, Transportation Research Board."},{"key":"ref_36","unstructured":"IEEE Computer Society LAN\/MAN Standards Committee (2016). IEEE Standard for Information technology\u2013Telecommunications and information exchange between systems Local and metropolitan area networks\u2013Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE Std 802.11-2016 (Revision of IEEE Std 802.11-2012), 1\u20133534."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Tian, B., Hou, K.M., and Zhou, H. (2016). The traffic adaptive data dissemination (TrAD) protocol for both urban and highway scenarios. Sensors, 16.","DOI":"10.3390\/s16060920"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1109\/TMC.2010.133","article-title":"Bidirectionally coupled network and road traffic simulation for improved IVC analysis","volume":"10","author":"Sommer","year":"2011","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Meinil\u00e4, J., Ky\u00f6sti, P., J\u00e4ms\u00e4, T., and Hentil\u00e4, L. (2009). WINNER II channel models. Radio Technol. Concepts IMT-Adv., 39\u201392.","DOI":"10.1002\/9780470748077.ch3"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1049\/itr2.12015","article-title":"Joint use of DSRC and C-V2X for V2X communications in the 5.9 GHz ITS band","volume":"15","author":"Ansari","year":"2021","journal-title":"IET Intell. Transp. Syst."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Zhao, L., Fang, J., Hu, J., Li, Y., Lin, L., Shi, Y., and Li, C. (2018, January 3\u20136). The performance comparison of LTE-V2X and IEEE 802.11 p. Proceedings of the 2018 IEEE 87th Vehicular Technology Conference (VTC Spring), Porto, Portugal.","DOI":"10.1109\/VTCSpring.2018.8417813"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Ahmed, S., Huda, M.N., Rajbhandari, S., Saha, C., Elshaw, M., and Kanarachos, S. (2019). Pedestrian and cyclist detection and intent estimation for autonomous vehicles: A survey. Appl. Sci., 9.","DOI":"10.3390\/app9112335"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1109\/MITS.2017.2743201","article-title":"Implementation and evaluation of a cooperative vehicle-to-pedestrian safety application","volume":"9","author":"Mahjoub","year":"2017","journal-title":"IEEE Intell. Transp. Syst. Mag."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"4773","DOI":"10.1109\/TITS.2019.2946642","article-title":"Intention recognition of pedestrians and cyclists by 2d pose estimation","volume":"21","author":"Fang","year":"2019","journal-title":"IEEE Trans. Intell. Transp. Syst."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Torres, S., C\u00e9spedes, S., Bustos-Jim\u00e9nez, J., and Serrano, M. (2019, January 15\u201318). IoT solutions for Sustainable Cities: An Online Adaptation for the Driver Intent Inference Algorithm. Proceedings of the 2019 IEEE 5th World Forum on Internet of Things (WF-IoT), Limerick, Ireland.","DOI":"10.1109\/WF-IoT.2019.8767264"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Schulz, A.T., and Stiefelhagen, R. (July, January 28). Pedestrian intention recognition using latent-dynamic conditional random fields. Proceedings of the 2015 IEEE Intelligent Vehicles Symposium (IV), Seoul, Korea.","DOI":"10.1109\/IVS.2015.7225754"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Quintero, R., Parra, I., Lorenzo, J., Fern\u00e1ndez-Llorca, D., and Sotelo, M. (2017, January 16\u201319). Pedestrian intention recognition by means of a hidden markov model and body language. Proceedings of the 2017 IEEE 20th international conference on intelligent transportation systems (ITSC), Yokohama, Japan.","DOI":"10.1109\/ITSC.2017.8317766"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"70169","DOI":"10.1109\/ACCESS.2019.2919489","article-title":"IEEE 802.11 bd & 5G NR V2X: Evolution of radio access technologies for V2X communications","volume":"7","author":"Naik","year":"2019","journal-title":"IEEE Access"},{"key":"ref_49","unstructured":"(2021, April 23). IEEE P802.11-Task Group bd (NGV) Meeting Update. Available online: https:\/\/www.ieee802.org\/11\/Reports\/tgbd_update.htm."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Chen, X., Leng, S., and Wu, F. (2018, January 18\u201320). Reinforcement Learning Based Safety Message Broadcasting in Vehicular Networks. Proceedings of the 2018 10th International Conference on Wireless Communications and Signal Processing (WCSP), Hangzhou, China.","DOI":"10.1109\/WCSP.2018.8555733"},{"key":"ref_51","unstructured":"ETSI (2020). ETSI TS 103 300-2 Intelligent Transport System (ITS); Vulnerable Road Users (VRU) awareness ; Part 2: Functional Architecture and Requirements definition; Release 2, European Telecommunications Standards Institute (ETSI). Version 2.1.1."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/10\/3375\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:59:55Z","timestamp":1760162395000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/10\/3375"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,5,12]]},"references-count":51,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2021,5]]}},"alternative-id":["s21103375"],"URL":"https:\/\/doi.org\/10.3390\/s21103375","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,5,12]]}}}