2.2.2. Urban Mobility
Urban mobility is regarded as the key to achieving sustainable development goals, and it drives both economic development and social development
[43]. Mobility is the core component of a smart city because transportation provides vast amounts of citizen and vehicle data. Authorities are proposing mobility plans with a shift towards sustainable transport models, and urban transport is embracing the sharing economy via public and private initiatives
[44]. The challenge is militating against sustainable urban mobility, which is a source of concern for urban planners and policymakers because it is multi-dimensional, covering environmental performance, energy efficiency, the monitoring of behaviour and mobility, and the influencing of economic development
[45][46][47]. Another challenge in implementing sustainable urban mobility is integrating urban mobility systems and smartphone-enabled mobility services and modernising public transit services. Other urban mobility challenges include growing traffic congestion, quality of air reduction, physical inactivity, and reachable, reliable, safe, and affordable public transportation, as well as new homes and job creation
[48].
2.2.3. Ubiquitous Cities
Ubiquitous cities (u-cities) are an advanced level of smart cities with intelligent convergence systems. A u-city is a solution to problems confronting urban communities, such as weak security, poor levels of sustainability, and pollution. To determine the requirement for the platform to establish a u-city, Rad et al. [49] propose an effective conceptual framework that explores and measures the major indicators for a smart city, i.e., environments, citizenry, and infrastructures that are critical. A Tehran, Iran and Seoul, South Korea ubiquitous coefficient was computed. The results verified the robustness and effectiveness of the proposed framework’s accuracy in determining the ubiquitous conditions of the cities.
2.2.4. Outliers Detection
Knowledge extraction is a crucial task in urban computing for smart cities and becomes more significant when there are outliers in the big data. Souza, Aquino et al. [50] proposed a method for outlier detection by using the multiway nature of the data. The proposed method detects the outlier in big data by reducing dimensionality, classifying latent factors, and combining both. The method was applied to four urban cities, and the outcome indicated that the proposed method produces a new clustering approach. The results are more accurate, and it takes data from different dimensions. The proposed method can also be integrated with other applications such as a cloud and further extended by adding more information such as climate, meteorological data, quality of water, etc.
2.3. Key Applications
Intelligent Transportation: Intelligent transport systems (ITSs) are among the major components of any urban computing smart city
[51]. Large-scale WSNs are used in intelligent transportation to monitor journey time online (including routing choices, wait times, air pollution, traffic jams, and noise emissions)
[52]. Different modes of transportation, cutting-edge infrastructure, and solutions for traffic and mobility management are all creatively offered by ITSs. ITSs have transformed the way and manner in which people commute in urban smart cities
[53]. IT is a novel transportation technique embedded with electronic equipment including wireless and communication systems for users to have easy access to smart, safe, and fast travelling channels. Some major features of an ITS include route information (it provides prior real-time information about travelling routes to users and enables them to decide the best route), safety and vehicle control (it enables drivers and also warns them about their driving proficiencies, road conditions, and vehicle performance), and electronic timetables (it provides travellers with detailed information concerning the arrival and departure times of vehicles, trains, etc.)
[54]. An ITS provides a suitable and comfortable living environment for people in smart cities by minimising the level of pollution and providing smart parking solutions
[55].
Smart Building: A smart building is embedded with ICTs and services by equipping appliances in the house through networks to improve living quality. Typically, an enterprise of intelligent devices is embedded in a smart building to offer unique services at home that are typically absent in conventional buildings for the benefit of the users
[56]. It uses technology to equip devices powered via energy efficiency, cost-effectiveness, and Wi-Fi. These devices are used for intelligent monitoring and remote control that automatically provide harmonic interaction between them without human intervention
[57]. A cyber-physical system (CPS) is a typical illustration of a smart building
[58][59] providing comfort, a secure environment and safety, low power consumption, and ubiquitous convenience. Smart building services can be further improved by adding health functionalities to the cloud services, such as the issues of blood pressure and heart rate, that are typically not feasible to have in systems embedded locally
[60].
Smart Vehicles: Because of the increasing rise in urban communities, smart cities have attracted a lot of interest. With the developing nature of smart city environments, different smart objects are integrated together and transformed into smart systems
[61]. To leverage the present challenges such as pollution and energy consumption imposed on a smart city, vehicular cloud computing is provided. Recently, the rapid evolution in terms of “automotive technology and on-demand transportation services” in smart cities has led to the development of smart vehicles
[62], which are equipped with wireless connectivity and autonomous capability to reduce the level of carbon production in smart cities. A smart vehicle is a major enabler for smart city environs because it is equipped with additional onboard gear to enable on-demand services for vehicle occupants
[63]. Smart vehicles are implemented using IEEE 802.11.p and IEEE 1609 standards
[64] that enable communication and the retrieval of information from the vehicle's environs. Given the importance of smart vehicles in a smart city environment, there has been an increase in the adaptation of vehicle-to-vehicle communication, allowing vehicles to exchange information. As such, vehicles can transmit certain information such as destination and speed wirelessly without human intervention. Messages and warnings alert a driver to the need to control vehicle movement to avoid an accident. Sending messages, such as that he is more than 300 m away, can inform a driver about different conditions such as traffic, weather, threats, and information that is of general use
[65].
Smart Mobility: Urbanisation introduces new challenges to a smart city project in the 21st century and has prompted problems such as traffic, pollution, and transportation systems
[66]. These problems have prompted stakeholders to explore data as a result of operations in urban areas, such as power consumption, congestion as a result of traffic, etc. Smart mobility is a system that makes decisions about traffic and pollution based on the data extracted on traffic and pollution. Subsequently, routes are recommended according to the preference of users or to ease traffic congestion. Smart mobility has the capacity to make a smart city look attractive and beautiful and promote business expansion by easing the flow of traffic in the smart city
[67][68]. An intelligent mobility approach is required to guide and support inhabitants living in smart cities
[69]. Different preferences differ among pedestrians, motorists, and cyclists in view of the fact that some prefer a route without crowds no matter the distance to the destination, while others prefer the shortest possible route regardless of crowds. On the other hand, some prefer the route with minimal pollution because of health complications or low-quality air
[70].
Smart Grid (SG): An SG is a power system with operational and energy measures that are integrated with a communication infrastructure to provide energy flow in a bi-directional manner and information
[71]). The tremendous energy demand in smart cities has ushered in the SG evolution
[72]. An SG is a smart electrical distribution system with various power functions, including smart meters, sustainability of energy, smart machines, and energy effectiveness. The energy properties are responsible for the energy distribution flow in a bi-directional manner between manufacturers and users
[73]. SGs are currently adopted across the world to achieve sustainability objectives and secure and economic power supplies with users that are active in participating in using advanced metering infrastructure as well as home energy management
[74]. The general packet radio service is an SG communication technology used for long-distance data transfer over a circuit switch
[75]. An SG that operates globally has to use microwave access technology that uses IEEE 802.16 that provides long-range data transfer services and monitors the network's status
[76]. Another communication technology of SGs is Bluetooth (IEEE 802.15), which has a low power consumption ability and operates with a frequency of 2.4 GHz to manage and monitor the power system. ZigBee (IEEE 802.15.4) is an application generally accepted in SGs because of its high level of energy efficiency, which makes it consume energy at a lower rate
[58].
Smart Communities: Smart communities are the basic components of a city
[77] that uses connected technologies to improve smart city infrastructure, regardless of the size of the city. A smart community involves city planners who monitor and collect traffic data to improve the city’s transportation system and the community’s competitiveness
[78]. The collected data lead to implementing the new transportation system within communities to reduce the rate of accidents and travel times. A study by Kulkarni and Farnham
[79] predicted that by 2020, the value of smart communities in the global market will be approximately $1.6 trillion. In addition, smart communities have the potential to significantly boost community life by enabling people to react to environmental changes and earn a living and empowering them to contribute to society
[80].
2.4. Implications
Security: The communication technologies used for effective communication in urban computing in smart cities are WSNs, RFID, Wi-Fi, 4G LTE, LTE-Advanced (LTE-A), and 5G [81][82]. Each of these technologies is exposed to different security issues due to the components used in developing them. For WSNs, sensors and actuators are the main elements that make WSNs flexible and incur high communication latency. These characteristics make WSNs prone to cyber-attacks [83]. However, in a smart city, the security related to the WSN can be based on the confidentiality of data, authentication, integrity, and freshness. The four security issues related to WSNs can be mitigated based on cryptographic algorithms, management, routing that is secured, and trust of the node [83]. For RFID, the possible security issues that arise from RFID are tracking, DoS, repudiation, spoofing, alteration, corruption and deletion, eavesdropping, and counterfeiting. For urban computing in smart cities, RFID technology is mainly used for the automated exchange of information without any manual involvement and can work in harsh environments [84].
Privacy: The vision of a smart city is to improve facilities in urban areas with the incorporation of technological tools into facilities such as the SG, transportation system, government institutions, schools, etc. [85], to enhance living standards wirelessly. With the mode of communication among connected devices in smart cities, data privacy poses a major challenge in the network because data intrusion from malicious devices can temporarily stop the services provided by the smart city [85].
Ethics: Ethical evaluation is the fundamental component required for the acceptance of smart city technologies. Urban computing and smart-city-enabled technologies have become essential components for urban city functionalities
[86]. Urban operational controls and city services are becoming highly responsive to data-driven modes. As a result, there is a need to design and deploy ethics for both users and smart city application developers. Some of the main ethical designs involve personal privacy, obtrusiveness, stigma and autonomy, and data sharing and autonomy
[86]. Personal privacy has complex phases
[87].
Data sharing and autonomy involve the right of users to make personal decisions with respect to freedom and independence, specifically in reference to assistive technologies such as smart homes, SGs, power plants, etc. It deals with the aspects of privacy that are not directly connected to the control of data, and it includes both physical and social aspects
[88]. However, privacy is the major prerequisite for autonomy
[86][88].