Dear Colleagues, It is our pleasure to invite you to submit your latest research results to the 18th Int. Conf. on Wireless Networks and Mobile Systems (WINSYS 2021), that will be held Online from July 07 to July 09, 2021, until the 29th of April. Please notice this is a hard deadline and will not be extended. WINSYS 2021 is an annual conference whose goal is to bring together researchers, engineers and practitioners interested on information systems and applications in the context of wireless networks and mobile technologies. Information systems and information technology are pervasive in the whole communications field, which is quite vast, encompassing a large number of research topics and applications: from practical issues to the more abstract theoretical aspects of communication; from low level protocols to high-level networking and applications; from wireless networking technologies to mobile information systems; many other topics are included in the scope of WINSYS. The conference will include in its technical program remarkable distinguished speakers, such as: Shahid Mumtaz, Instituto de Telecomunicações, Portugal Sandra Sendra, Univ. Politécnica de Valencia, Spain Muhammad Sajjad, NTNU, Norway The conference proceedings will be submitted for indexation by: SCOPUS, Google Scholar, The DBLP Computer Science Bibliography, Semantic Scholar, Microsoft Academic, Engineering Index (EI), Web of Science / Conference Proceedings Citation Index and a short list of presented papers will be selected so that revised and extended versions of these papers will be published by Springer in a CCIS Series book. Also, a short list of best papers will be invited for a post-conference special issue in the <https://www.mdpi.com/journal/electronics> Electronics Journal (Impact factor: 2.412 CITESCORE 1.9 SCOPUS) and another short list of best papers will be invited for a post-conference special issue in Springer Nature Computer Science journal. All papers presented at the conference venue will also be available at the SCITEPRESS Digital Library. Kind regards, Mónica Saramago On behalf of Conference Chair Jaime Lloret Mauri, Universidad Politecnica de Valencia, Spain Program Chair Joel Rodrigues, Federal University of Piauí (UFPI), Teresina - Pi, Brazil; Instituto de Telecomunicações, Portugal Web: http://www.winsys.org e-mail: winsys.secretariat@insticc.org <mailto:winsys.secretariat@insticc.org>