# Internet of Things: A Scientometric Review
## 4 Research Topics
### Communication Protocols According to Open Systems Interconnection Model (OSI Model)  
Regarding telecommunications systems, the Open Systems Interconnection model (OSI model) describes the communications process in seven layers which are divided into media layers (Physical, Data, and Network) and host layers (Transport, Session, Presentation, and Application) [152]. In this review on IoT, the most used communication protocols are divided into these two layers (see Table 6). Figure 6 shows the yearly trend of the different communications protocols for media layers in Figure 5(a) and host layers in Figure 5(a). RFID is the top used author's keyword in the analyzed data set and the most used media layer communication protocol in the authors' research. On IoT 923 publications are related to RFID, where security authentication [153; 154; 155], wireless sensors networks [156; 157], privacy [158; 159], and electronic product code (ECP) [160; 161] were major applications. Next, 6 LoWPAN appears in 230 publications, with documents related to upper layer protocols such as Constrained Application Protocol (CoAP) [162; 163], Routing Protocol for Low power and Lossy Networks (RPL) [164; 165], and operating systems like Contiki [166; 167], and Android [168; 169]. With similar growth, ZigBee follows with 222 documents, and research integrates this protocol with solutions such as RFID [170; 171; 172], or applications like smart home [95; 173; 174], and health care [175; 176; 177]. Bluetooth Low Energy (BLE) has experienced a rapid growth in the last three years, near 100% from 2015 to 2016. A total of 98 documents on IoT are related to BLE, with one of the most cited articles by [PERSON] et al. at 176 citations. In this article, the authors describe the main features and potential applications for BLE technology [178]. This data set shows BLE related applications such as home automation [179; 180; 181] and indoor location [182; 183; 184] and health care [185; 186; 187]. WiFi is the other network protocol used for IoT research, with a total of 85 publications, and applications related to: home automation [188; 189], indoor localization [190]. Nevertheless, with this wireless technology, some authors have focused on how the 2.4 GHz spectrum could be efficiently used with other IoT network protocols [191; 192; 193; 194; 195; 196; 197]. Similarly, 5 th generation mobile n \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Layer** & **IoT Communication Protocols** \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} **Host** \\ **layers** \\ \end{tabular} } & 7. Application & \\  & 6. Presentation & CoAP, MQTT, JSON, iBeacon \\  & 5. Session & \\ \cline{2-3}  & 4. Transport & TCP, UDP, DTLS \\ \hline \multirow{2}{*}{
\begin{tabular}{c} **Media** \\ **layers** \\ \end{tabular} } & 3. Network & IPv6, 6 LowPAN, ZigBee, BLE, RPL \\ \cline{2-3}  & 2. Data link & RFID, 802.15.4, WiFi, BLE, 5G \\ \hline \hline \end{tabular} Abbreviations definition: Constrained Application Protocol (CoAP), Message Queue Telemetry Transport (MQTT), JavaScript Object Notation (SON), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Datagram Transport Layer Security (DTLS), Internet Protocol version 6 (IPv6), IPv6 over Low-Power Wireless Personal Area Networks (6 LoWPAN), Bluetooth Low Energy (BLE), Routing Protocol for Low power and Lossy Networks (RPL), Radio-frequency identification (RFID).  
\end{table} 
Table 6: Internet of Things Open Systems Interconnection model (OSI model) communication protocols. Figure 6: Internet of Things media and host layers communication protocols based on authors’ keywords in documents per year, for the 2006 to 2016 period. (**a**) media layers’ communications protocols; (**b**) host layers’ communication protocols. with 82 publications, much more than 4G and LTE, with 54 documents both combined. The most cited paper is a suvery on 5G architecture and emerging technologies written by [PERSON] et al. [198] with 109 citations.