Message querying telemetry transfer on IoT applications to enhance technology: a systematic review

More things are connected to the Internet, making the internet of things (IoT) develop significantly. But IoT also has weaknesses in communication, one of which can be overcome by utilizing message querying telemetry transfer (MQTT) because there are too many benefits of MQTT. Because there have been many published studies regarding MQTT, this study aims to conduct a review utilizing preferred reporting items for systematic reviews and meta-analyses (PRISMA) on the application of MQTT in IoT applications to enhance technology. The results of using PRISMA were 57 papers selected from this process, which starts from the identification stage, screening, eligibility, and included. The last author found components that can be discussed to enhance technology. In this discussion, several topics will be used to enhance technology, such as; smart technology, security, MQTT performance for IoT, monitoring systems, MQTT comparison, enhancement or optimization. This paper is expected to help academia and industry related to MQTT research that can help IoT to enhance technology quality.


INTRODUCTION
There have been enough uses for the internet of things (IoT) devices because they have lightweight capabilities and affordable prices. Many of their applications in IoT devices can connect and communicate with each other using the Internet because they have the services needed by most people. This technology develops through things related to the Internet, so its application is easy and fast. These technologies sometimes have additional reasons for being "smart", usually having relationships such as home automation, smart agriculture, smart cities, health systems, smart gardening, smart grids, smart vehicles, and smart culture. A British technology pioneer named Kevin Ashton 1999 gave terms by naming the ''internet of things'' [1]. The "things" principle is currently developing very significantly. The main goal is to make information by sensing without anyone's help. In the IoT, it is predictable that the integration of all "things" is realized by building intelligent interfaces between the functions of device utilization. IoT can utilize IoT gateways to connect points between applications and smart IoT devices for connection. Smart for sensing and collecting data from the environment is the task of the IoT. This evolution continues to grow, especially those that utilize; actuators, sensors, and other micro components [2].
People rapidly push towards IoT based on increasing the quality of life through connections for everything, starting from many personal devices to other devices out there, for example, medical devices (e.g. medical aids), burglar alarms, car fire alarms and massive sensor use. The many facilities that IoT can use

PRISMA method
At this stage in achieving the goals, this study will focus on PRISMA, a recommended framework to help carry out a systematic review and report [18]. As a new strategy, researchers conducted in January 2022 a focused search on MQTT utilizing a search focused on scientific articles. After that, in March 2022, a new search was carried out in the same place using the MQTT database to search for papers published in 2019-2022. Sorting this database must look at its relevance and scope so that it can affect the academic world because this database must focus on publishers such as IEEE, ACM, and MDPI. Besides being widely used in the systematic review.
In this study, search for the term "Search String" in several fields ("MQTT" OR "message queuing telemetry transport") AND ("internet of things" OR "IoT") AND ("internet of things applications" OR "IoT applications") AND ("enchance technology" OR "improve technology). The advanced stage (following the pattern of [25]) is that papers are validated so that they are considered valid if: i) the paper taken is not a study, review, or challenge in the future, case studies that are considered if appropriate to the topic; ii) are closely related to the topic and research objectives; iii) presents an improvement in technology by utilizing MQTT on IoT Applications; and iv) published papers must be in English. By utilizing the PRISMA model [18], using PRISMA, here find a meta-analysis of several existing studies.
This systematic review method does not use statistical models, only searches based on recent reviews. Figure 2 shows the results of the first PRISMA Flow identification, which got 2,488 papers carried out at the identification stage. The screening was carried out to get 1,247 papers, then the eligibility stage with 249 results, then the final stage, which got selected articles in this study in the form of 57 study papers that can be done as a study that will enhance technology in IoT applications. The flowchart of PRISMA [18], (pattern inspired by previous [25]) is presented in Figure 2.

PRISMA result
This section is the result of the selected paper (see Figure 2) and will be explained by classifying the obtained studies as shown in Table 1. Then, where did this study come from in Table 2 (focus on the first author). The last is the distribution of years presented in Table 3. Furthermore, Table 4 explains the distribution of articles by year (2019-2022) (in research results, there are still those paper that uses the constraint application protocol (CoAP), but the focus remains on the results of using MQTT on IoT).  Routing based protocol [82] As shown in Table 1, several topics have been discussed in 2019-2022, such as smart technology, security, MQTT performance for IoT, monitoring systems, MQTT comparison, enhancement or optimization. The author will further explain these topics in the discussion section. The results of this presentation are also useful in viewing articles about MQTT on IoT applications. Furthermore, Table 2 shows the distribution (focus on the first author) of research on MQTT on IoT applications to enhance technology from papers mostly from India, as many as 10 papers. These results show that a lot of research conducted in the area can be used for academics and industry in conducting research benchmarks there. Table 3 shows publishers' distribution because most came from the IEEE and then continued with MDPI, ACM, and ScienceDirect. So that many related articles can be published in IEEE publishers. This indicates that the articles prefer IEEE articles in publishing related articles.  presents the distribution by year, and for the 2019-2022 period, the most research was still in 2019, but it can also be seen that for 2022, which is currently ongoing, many studies have been published.   Suppose the author compares with similar research papers [5], which utilize PRISMA as a systematic review. In that case, this paper presents a summary of related research (IoT and MQTT). The results presented are more detailed and easier to use as references for related academics or industries. Results can also be used to enhance research or find related results supporting existing research.

Discussion
In this section, there will be a discussion on the most researched topics (see Table 1). The growing trend in the number of papers on IoT applications utilizing MQTT in technology improvement and those observed since 2019 will be outlined in several discussions regarding the findings. Obtained from PRISMA. The author gives some snapshots like glossaries for the IoT and MQTT. In this discussion, several papers that have been widely researched and received attention for technological developments (see Table 1) by study in 2019-2022 based on Figure 3. As shown in Figure 3, the author will describe the topic in more detail by dividing it into several sections described in the following sub-chapters.

Smart technology
The concept of IoT that can connect several objects, and other things and be integrated with the Internet is an attraction in itself. In many studies, MQTT helps IoT in "smart" concepts like smart agriculture and smart cities. Many studies have focused on smart technology because of its nature that can automate and facilitate other things. This concept has indeed become a material that researchers and industry often use. This is part of a technological improvement that has been successfully enhanced by utilizing the MQTT protocol. Apart from improving its quality, it also helps users implement the "smart" concept. Research on smart technology that utilizes MQTT is found in [27]- [32].

Security
MQTT is a protocol that is often used because it is lightweight and effortless to use if operated remotely. Because MQTT is widely used due to minimal bandwidth and low memory consumption, but also has some drawbacks stemming from several types of attacks [46]. Then there is a study on external attacks such as denial-of-service (DoS) [38], and intrusion is some examples of attacks on brokers [43]. Therefore a lot of research on security (DoS, intrusion detection) [33]- [46].

MQTT performance for IoT
Knowing performance is very important because IoT requires excellent performance compared to the lightweight nature of MQTT. Protocol research has been carried out by measuring the quality of service (QoS). Looking at the version of MQTT, it can also be seen that operations at different QoS levels can impact latency when sending data [48], because it feels MQTT is needed to measure its performance in helping IoT. Another performance measurement can also be made for smart cities [49]. MQTT performance is also considered in NB-IoT smart meter [50]. Then many other studies focus on analyzing the performance of MQTT [48]- [53].

Monitoring system
Monitoring is an important thing used in IoT because monitoring is real-time. It needs a supporting protocol to maximize IoT performance. In addition to utilizing sensors, IoT also uses MQTT. This protocol, for example, can be used for radon gas monitoring [58]. And also, can be used in soil humidity monitoring [59]. Furthermore, many more studies regarding monitoring systems [58]- [64].

MQTT comparison, enhancement or optimization
Performing comparison, enhancement, or optimization is made by several methods, protocols, and even technologies. Comparisons, optimizations, and enhancements are used to find out the improvements or changes to workability, especially MQTT, which should help IoT as a lightweight protocol. MQTT can perform message routing algorithms for optimizing communication between cloud microservices [68]. MQTT also enhances transparency among MQTT brokers [69]. Several other studies can compare, enhance or optimize MQTT [68]- [71].

CONCLUSION
This study seeks to review research on MQTT in IoT applications to enhance technology. This study conducted a systematic review using PRISMA, this method is very good and traceable in conducting a systematic review, but its use can be different. This paper focuses more on presenting results than is needed for academia and industry in conducting experiments and further systematic reviews. This method uses four stages: identification, screening, and feasibility, incl. At the identification stage to look for the latest papers (2019-2022), around 2,488 scientific papers were obtained, then the screening stage was 1,247, and the next stage was the feasibility of 249 papers. Finally, the authors get 57 papers that are eligible to be used in the

Ranny
got her master's degree in Computer Science from Universitas Indonesia in 2013. Now, she joins as a Faculty Member at the University of Bina Nusantara, also a candidate doctoral in Information Technology, Institut Teknologi Bandung. Her research lines are artificial intelligence for sound processing. She can be contacted at email: ranny@binus.ac.id.