*1.3. Paper Organization*

The remainder of the paper is organized into the following sections. Table 1 presents the notation used in the entire paper. Section 2 provides the related works. Comparative analyses of these review papers are given in Table 2. Section 3 presents a detailed systematic literature survey (SLR). Research questions presented in Table 3 are addressed in Section 4. Section 5 presents the challenges and issues. Future directions are elaborated in Section 6. Finally, the conclusion is presented in Section 7.


**Table 1.** List of Abbreviations.


### **2. Related Studies**

In this section, we analyze the state-of-the-art research studies on IoT and WSN. With the fourth industrial revolution, it is observed that communication, computation, and storage costs have remarkably decreased, which make integration of IoT and WSN possible and cost-effective globally. We studied many review articles and original research. Existing review articles lack, in many aspects, research challenges, issues, limitations, and future directions of IoT and WSN, but the systematic literature review (SLR) given in this work is precise enough to deal with the aspects of IoT and WSN area. Related work of review papers is provided next. Moreover, Table 2 is presented which shows the comparison between the proposed research work and the existing state-of-the-art analysis.

**Table 2.** Comparative analysis of the existing review papers. Key: deployment category—DC, literature review—LR, security overview—SO, bibliometric literature review—BLR, systematic literature review—SLR.



The authors in [1] discussed the very novel technology "WiFi". They discussed how this technology helps IoT devices–used in various applications, such as smart cities, healthcare systems, and smart houses—communicate effectively. Landaluce et al. [4] discussed RFID and WSN technology in detail. They discussed how RFIDs are used to trace devices while WSN gathers information about them from interconnected devices. The authors also discussed the obstacles and challenges, such as energy consumption, faulttolerant, communication interference, and cost feasibility, along with detailed surveys. They provided the advantages and limitations of wearable sensor devices. Energy consumption is increasing each day. Therefore, Dailipi [4] explored how IoT evolution has managed the electricity consumption process and provided many benefits to grid stations, consumers, and suppliers. They also discussed the security issues and challenges after introducing IoT devices in smart grids.

In [6], the authors discussed how WSN advancement had played a significant role in UASN. They traced the location of sensor nodes deployed underwater in the ocean using localization algorithms. They reviewed many applications of UASN, their advantages and their disadvantages. They also discussed the challenges they faced during deployment and presented future directions in the acoustic area. In [10], researchers discussed the

applications and advantages of WSN being deployed everywhere due to their flexible and dynamic nature. They discussed each application of WSN in urban areas and their solutions. They analyzed how WSN deployment in urban areas demanded much more care and attention due to harsh weather and perverse channel conditions.

WSN is applicable in many domains, such as industrial automation, and the requirement elicitation of the industrial process is different from general WSN requirement gatherings. In [17], the authors presented some standard protocols that were used to measure the requirements of industrial applications. They also provide solutions to WSN protocols by discussing MAC, routing, and transport in detail. They also discussed the security issues in detail and identified the unsolved challenges encountered during designing standard protocols. In [19], the authors conducted SLR, which is mainly focused on scope definition, concept, literature review, analysis, synthesis, and future research directions. Their selected study has contributed to eight thematic perspectives: intelligence factories, CPS, data handling, IT infrastructure, digital transformation, HCI, IoT, and cloud [18].

Due to the rapid evolution in IoT and WSN, technology is becoming more vulnerable to security threats [42–44]. Therefore authors in [27] presented threat models for the security of WSN and IoT devices communication. In [28], the authors discussed IoT applications, advantages, challenges, and security issues from both technological and social perspectives. Researchers have provided detailed architectures of IoT and WSN and discussions of IDS system protocols. They also discussed the security challenges and attacks on IoT and WSN communication devices. Moreover, in [29], the authors conducted extensive research related to smart homes, applications, and IoT. They collected 229 articles, analyzed them thoroughly, and divided them into four categories. They discussed smart home IoT applications in the first category. The second category concerned with IoT applications in smart home technology. In the third category, they developed a framework to operate further. In the fourth category, they developed smart IoT home applications.

IoT has dramatically changed human life, especially regarding communication devices integrating technologies. Traditional industry is changing in the digital industry, and WSN and wireless sensor and actuator networks (WSANs) are the core parts of Industry 4.0. In the article [30], the authors discussed the industrial wireless sensor network (IWSN) and industrial wireless sensor and actuator network (IWSAN) in detail. They discussed IWSAN requirements, applications, challenges, solutions, and future directions in detail. IWSN/IWSAN are compelling technologies due to their promising benefits, such as lowcost deployment, less complexity, and mobility support.

In [31], the authors discussed how IoT plays a vital role in bringing the physical world close to the digital world. They discussed technologies, various challenges, future directions, and various Internet of Things (IoT) applications.

In [32], Sharma et al. have described the sensor nodes according to coverage point of view. They analyzed the full coverage issues by considering node type, deployment type, communication and sensing range, and positioning-based independent algorithms. They also discussed the research challenges of WSN.

Andrey et al. [33] described a detailed survey on IDS systems and presented the methods proposed for IoT. Using a cross-platform distributed approach, they analyzed the IDS system, their platform differences, and current research trends in IDS. In [34], the authors analyzed and discussed the solutions to identify and detect sinkhole attacks in the WSN domain. They discussed the advantages and limitations of the proposed solution as well. In [35], the authors presented a detailed review on security attacks of WSN and IoT along with their preventive measures, mitigations, and detection mechanisms. They stated that the integration of IoT and WSN has raised new challenges and open security issues. Although technology has increased, it has become prone to external attacks.

In [36], the authors presented a review on the security of mobile networks. They discussed the integration of WSN with IoT via the Internet and how the inter-connected devices have guarded networks against external attacks, keeping the router in a secure and protected environment. They discussed the attacks and their detection mechanisms over the

Internet. Similarly, the authors in [37] have discussed the wormhole attack and its solution in IoT and WSN domains. They stated that the detection algorithm performed much better for IoT (70%) than WSN (20%). In [45], the authors discussed side-channel attacks in smartphones. Similarly, the authors in [38] discussed the security threats, challenges, and solutions in the IoT domain. While in [39], the authors analyzed existing protocols for secure communication between IoT devices. They also discussed open issues and challenges raised during the communication of IoT devices and future directions in IoT. The authors in [40] presented a detailed review regarding deployment schemes, classification, working, and comparative analyses of sensor nodes. This growing technology trend has converged the "world sense" from traditional systems to CPS—this transition is called Industry 4.0. The authors in [41] conducted a bibliometric review of 12 different approaches of critical aspects of Industry 4.0.

From the above-detailed literature review, we noticed that authors and researchers have worked on IoT and WSN, but the integration of both IoT & WSN with Industry 4.0 is benign. They discussed their applications, security attacks, advantages, and limitations at each level.

The proposed paper is more oriented towards the applications and contributions of IoT and WSN in Industry 4.0, along with the security attacks, their challenges, and open issues in each domain. This paper also provides the limitations and future directions for IoT and WSN in Industry 4.0.
