# A Systematic Literature Review on Military Software Defined Networks
## 3 Research Method  
For the execution of this study we utilized the method described by [PERSON] and [PERSON] [14], for conducting systematic literature reviews of information systems research, adopting additional useful components from the studies presented in Section 2, and particularly articles [4; 5]. This method is comprised of the following distinct steps:  
1. _\"Purpose of the literature review:\"_ For our study, the \"Purpose of the literature review\" has been defined as: to analyze the current state of the art within the topic of military SDN, in terms of research tracks, publications, methods, trends, and to make recommendations for future research. Accordingly the executed tasks seek to satisfy the following explicit goals: 1. To identify and classify the research papers published on the topic of military SDN; 2. To analyze and evaluate the research papers published on the topic of military SDN and summarize the related research results; 3. To identify the most active and influential researchers, groups, conferences, and journals, on military SDN; 4. To identify the current main focus areas within the topic of military SDN; 5. To make recommendations for future research. 2. _\"Searching for the literature:\"_ The identification and extraction of related literature was finalized on 15 August 2018, in the following academic research databases: IEEE Xplore, ACM Digital Library, ResearchGate, Microsoft Academic Search, ScienceDirect, CiteSeerX, Scopus, ProQuest, BIBSYS, and Semantic Scholar. Furthermore, this process has been executed by explicit combination of two groups of key-words, where the first group of terms was related to the technology (i.e., SDN, Software Defined Networks) and the second on the application domain (i.e., Military, Strategic, Tactical), providing a total of six combinations for each database. Seeking to maximize comprehensiveness and extract the whole of related articles, we transferred the weight of inclusion on the next step (practical screening), by selecting to utilize the majority of academic research databases (accepting the risk of multiple duplicate outputs), and selecting wide terms as key-words (accepting the risk of outputs with limited relevance to the purpose of this literature review). 3. _\"Practical screening:\"_ For the selection of articles and mitigation of the aforementioned risks, we defined several exclusion criteria and rounds, as follows: 1. Articles published in languages other than English have been excluded. 2. Duplicate articles occurring across the examined scientific databases have been excluded. 3. Reports, presentations, editorials, and posters have been excluded, while we selected only scientific articles published in conferences, workshops, and journals. Furthermore, we have included PhD, and MSc thesis of significant relevance to the examined topic. * The article must be directly related to SDN or in combination with relevant fields, such as NFV (Network Function Virtualization) or SDR (Software Defined Radio), but not only on related fields without mentioning SDN. * No exclusion criteria have been defined in accordance with the year of publication, publisher, and author affiliation. * _\"Quality appraisal:\"_ The initial database screening, with the search method and exclusion criteria described in the two previous paragraphs, resulted in 927 entries. At this stage, the authors defined and individually applied an application domain related filter, seeking to identify scientific contributions with relevance to the purpose of this literature review. This filter was defined as: _\"The article must be directed to military networks or clearly mention military networks as a potential application domain for the presented contribution.\"_ Consolidating the three individual recommendations resulted in the final list of entries that are presented in this literature review. Consequently, these articles have been independently evaluated in terms of relevance, significance, and impact.