The Role of Internet of Things (IoT) in Smart Cities: Technology Roadmap-oriented Approaches

: Since the concept of a smart city was introduced, IoT (Internet of Things) has beenconsidered the key infrastructure in a smart city. However, there are currently no detailed explanations of the technical contributions of IoT in terms of the management, development, and improvements of smart cities. Therefore, the current study describes the importance of IoT technologies on the technology roadmap (TRM) of a smart city. Moreover, the survey with about 200 experts was conducted to investigate both the importance and essentiality of detail components of IoT technologies for a smart city. Based on the survey results, the focal points and essential elements for the successful developments of a smart city are presented.


Introduction
The term "smart city" refers to new industries utilizing information and communication technologies (ICT) along with the functions and environments of urban areas [1].In a narrow sense, the term refers to the combination and integration between ICT and urban functions.However, the term smart city can also be described in a wide sense as the convergence of ICT, the ecological environment, energy technologies, and support facilities within urban and residential environments [2,3].
The concept of the smart city has emerged for good reason.First, because the majority of new jobs are being created in urban areas, the expansion of such areas is accelerating [4].Second, to enrich the educational opportunities for their children, a large number of families in rural regions are moving to urban areas.For example, the population growth rate in urban regions in South Korea has been contributed to by a population outflow from rural areas [5].With this trend, several significant problems have been occurring.To adopt such an influx of population, the infrastructure and facilities in urban areas should be expanded [6].Moreover, solutions to respond to various problems such as environmental and transportation issues occurring in urban areas should be prepared [7].Therefore, the concept of the smart city has been introduced to eliminate these problems.To prepare the basic infrastructure of a smart city, various sensors, support technologies, and background environments are essential and are being employed in urban areas.Among them, the Internet of Things (IoT) is considered one of the most important aspects for the successful implementation of a smart city [8].
IoT is referred to as "a set of technologies for accessing the data collected by various devices through wireless and wired Internet networks" [9].Although there are notable differences in the definitions of IoT, a common explanation is the ability to provide valuable and beneficial information by various user devices through wireless and wired Internet networks.
In 2017, about 1.6 billion IoT components and devices were used in smart cities, an increase of 39% compared to 2015.Moreover, the numbers of IoT components and devices in 2017 and 2018 are expected to show an increase of 42% and 43%, respectively.By 2018, about 3.3 billion IoT components and devices are expected to be utilized in smart cities [10].The basic concept of a smart city is summarized in Table 1.

Components Descriptions
Policy and purpose • Environmental sustainability: energy efficiency, environment pollution, and resources • Economic needs: public security, education, medical care and healthcare, and social stability As presented in Table 1, IoT is considered key infrastructure in a smart city [11].However, there are currently no detailed explanations of the technical contributions of IoT in terms of the management, development, and improvements of smart cities.Therefore, the current study describes the importance of IoT technologies on the technology roadmap (TRM) of a smart city.The remainder of the paper is organized as follows: Section 2 provides an overview of different IoT technologies.Section 3 presents the applied study method and results.Finally, Section 4 summarizes the findings and implications of the current study.

IoT in Smart Cities
Since the emergence of various types of networks, IoT has become one of the most important types of infrastructure in smart cities.For instance, to provide user-customized services, the data collected by electronic home appliances, including refrigerators, are shared and stored in a smart home environment [11,12].
Similar to the concept of a smart home environment, the smart city is an emerging market and an important part of future infrastructure.Because a smart city aims to utilize energy and electricity in an efficient manner, thereby providing a convenient and economically sound infrastructure for the well-being of society, the importance of IoT technologies is magnified.Therefore, after establishing the general infrastructure of a smart city, various services that need to employ and utilize diverse types of data collected in daily life can be provided.This means that various services utilizing IoT technologies in a smart city can bring about a sustainable and pleasant living environment for its citizens.
Therefore, to establish a sustainable urban environment, some notable industries are in collaboration and are considering the technological and social issues inherent to the future concepts implemented in a smart city.Table 2 summarizes the principal issues and agents for IoT technologies in a smart city.Moreover, prior studies summarized the key technical aspects of smart city technologies, and based on this summary, IoT technologies can be considered a necessary requirement [13].

Data
This study employed technology roadmaps for a smart city environment, which were investigated and proposed by a consortium of the South Korean government, two research firms for patent analysis, and government-funded research institutes with a number of professors working in smart city-related fields.Tables 3-5 show a summary of the technology roadmaps for a smart city.• Technology for converging more than two sensor functions • Various analytical and visualization technologies for the performance, prediction, modeling, and improvement of smart building based on big data

Procedure
A total of 198 professors and experts who responded that they have outstanding knowledge and insight into IoT technologies took part in the survey.Based on the extracted core technologies presented in Table 3, they were required to answer the following questions.

Results
Table 6 and Figures 1 and 2 show a summary of the main survey results.

Future Directions of IoT Technologies in Smart Cities
As shown in Table 4, IoT technologies contribute significantly to the majority of the detailed aspects of smart city technologies and infrastructure.Because the fundamental concepts and ideas of IoT technologies are shared with those of smart city technologies and infrastructure, a large number of business opportunities and extensive growth potential exist.Moreover, for the efficient and successful development of future IoT technologies in smart cities, the following points require focus.

•
Importance and essentiality: Sensor-oriented technologies for wireless networking are considered the top priority of IoT technologies for a smart city infrastructure (D.In addition to these points, there are some challenging aspects that should also be resolved.First, because IoT technologies should provide various operating systems, which includes low-to high-capacity processors, providing appropriately distributed resources is one of the most important tasks required in devices employing IoT technologies.Moreover, because the inclusion of more devices with IoT technologies in a smart city infrastructure leads to a significant number of additional computations and data transmissions, the technologies for intelligently optimizing, scheduling, and controlling such devices are essential.
Second, data management solutions are required for the massive amounts of data collected by various IoT technology devices because the majority of such data is unstructured or atypical.This means that technologies for data categorization and intelligent analysis should be developed and introduced.
Third, the current IoT technology services are provided through independent specialized solutions, which are oriented and operated within a specific environment.Therefore, compatible integrated applications for providing various IoT technology services should be developed and prepared by using appropriate network technologies.
Fourth, both appropriate solutions and plans for data security and privacy should be established.When users connect to an IoT technology service, reliable data processing and storage should be applied with confidentiality, integrity, and privacy.This means that reliable and safe communications and connections from each IoT technology device to the smart city infrastructure should be provided.

Conclusions
To realize the concept of a smart city, IoT technologies are one of the most essential elements in carrying forward detailed plans of a smart city.Regarding the various aspects of IoT technologies, the following points should be addressed.
Comprehensive demonstration sites for the testing of IoT technologies within a smart city infrastructure should be established.It is necessary to carry out government-led demonstrations of complex sites for promoting the smart city industry and markets.This will allow the participants within a smart city infrastructure to evaluate and verify the efficiency, economic feasibility, and influencing effects of developing IoT technologies and suggested services.Moreover, related technologies in the ICT industry for promoting IoT technologies should be investigated and developed in parallel.
In addition, to retain the sustainability of an urban environment with an ecosystem, a data-oriented smart city infrastructure should be developed and established.For example, globally advanced cities including Barcelona and London have opened to the public various types of data on their urban environments through verified online services.Such open data are employed to create new business models for startup companies utilizing IoT technologies in smart cities and to allow citizens to solve the current urban problems.
Based on the results of the current study, it is meaningful to present both necessary and priority issues regarding the aspects of IoT technologies for the successful establishment of a smart city infrastructure and its related services.
Although the current study evaluated the importance of IoT technologies with regard to the concept of a smart city, in-depth discussions and debates among experts and engineers in fields related to smart cities and IoT technologies should be continuously conducted for the provisioning of specific plans of action.Moreover, extensive professional panels of experts in diverse research fields including urban development, information and communication technologies, transportation, and environmental policies should be organized.

Figure 1 .
Figure 1.Summary of the survey results (items).

Figure 2 .
Figure 2. Summary of the survey results (category).

Table 2 .
Sectors, principal issues, and agents for IoT technologies in a smart city.

Sectors and Industries Key Services Principal Agents and Operators Core Issues for IoT Technologies
• Rapidly increased demand of autonomous or remote control services: utilizing wireless IoT sensing technologies or devices• Necessity in tracking medical teams and facilities located in hospitals• Requiring healthcare-IT convergence services based on electronic medical records and order communication systems

Table 3 .
Summary of technology roadmaps (TRMs) for smart city (Classifications A and B).

Table 4 .
Summary of TRMs for smart city (Classifications C and D).
[44]chnology for determining life patterns of user based on the investigation and collection of various types of sensing information C.2.3.Emotion recognition technology [42] • Technology for recognizing user emotions based on biometric data such as voice, facial expressions, EEG, EMG, skin electrical resistance, or behavior C.3.Home sensor-network technology C.3.1.Wireless sensing technology for home environment [17,43]• Sensing technology and measurement device for monitoring home environment using wireless networks (WiFi, cellular, or Bluetooth) C.3.2.Technology for providing services based on the collaboration of devices[44]

Table 5 .
Summary of technology roadmaps for smart city (Classification E and F).

Table 6 .
Summary of evaluations of importance and essentiality of IoT technologies.
Compared to other technologies, energy-related technologies are considered the most essential IoT technologies for the smart city infrastructure (A.1.1.Energy load management technology, F.2.3.BIM-based smart building energy management and analytical technology).Because the technologies applied in a smart home environment are fundamental aspects of a smart city, the technologies and infrastructure for a smart home network should be swiftly developed and prepared (A.1.2.Smart home cloud server technology).