Table 3 III. QUALITY ASSESMENT CRITERIA III. DISCUSSION AND RESULTS
Related Figures (8)
Fig. 1. Study Selection Process The study selection process of our systematic review is shown in Fig.2. This process consists of 3 parts, each part of the study selection was completed through proper concurrence and observed properly to remove biases from the extracted results. Hence, this ensures that our primary studies are not biased. Different digital libraries such as Wiley, Taylor & Francis, and Web of Science were not included during the systematic review. We selected the four digital libraries such as IEEE, ACM, Springer and Science Direct in our selection process because these libraries cover most of the research in a wide range. Further, we also take studies from an external database (Google scholar) to ensure the maximum studies cover, which is relevant to our field but most of these studies are rejected because of repetition. We select top 54 results from this external database at first and then filtered these studies by repetition, quality assessment, and _ inclusion- exclusion criteria. Fig. 2. Distribution of initial and final studies along with different databases The purpose of these criteria is to filter such articles that are not peer reviews or without validation. Through these criteria, the primary study will be mo domain on which we are conducting re related to the research our SLR. These criteria were applied upon the 2" and 3" part of our study selection process. As the 2" part is the inclusion of those results which have abstract related to our demand. So, these inclusion & exclusion criteria were applied to this part and 55 articles out of 190 were filtered on the base of these criteria. The 3“ part is the inclusion of articles that are total which had been decided on the base criteria that had been defined in assessment which is defined in Tab y relevant to our interest of inclusion & exclusion Table II and quality e III. These two criteria are applied parallel to the full text o application of both criteria, a total of f all 55 articles. After the 30 articles were selected for the final list of studies. Fig.2 shows the difference between an initial number of articles and the articles from the electronic database. final selected number of Fig. 3. Frequency of factors affecting the QoS of WLAN ABLE IV. MOST WIDELY USED FACTORS AFFECTING 802.11E A visual representation of the frequency of factors affecting the QoS of WLAN is shown in Fig. 3 Fig. 4. Chronological Distribution of studies from 2008-2019 Moreover, this research domain has received considerable attention from the research community from 2008 to 2019 as shown in Fig.4 which is the chronological distribution of studies. This graph signifies a decreasing trend towards QoS enhancement of the WLAN research area in the last decade. However, our SLR will provide a future direction for further research on this domain. Potential research directions and opportunities are available to work upon QoS enhancement of WLAN, especially on starvation issues. V3 MOST WIDELY USED TECHNIQUES TO RESOLVE ISSUES
