4. Roof inspections:

UAVs can inspect roofs for damage, such as missing shingles, cracks, or leaks. They can also capture images of the roof's overall condition and identify potential areas of weakness [157]. The problems resulting from roof damage are time sensitive and require quick decision making. For an effective decision, a big data-based AI algorithm may be utilized to provide these decisions.

## 2.9.4. Delivery Services

UAVs equipped with sensors can be used to deliver packages and goods in remote or hard-to-reach areas. This can provide faster and more efficient delivery services, especially in areas with limited transportation infrastructure [158]. Delivery services are increasingly turning to UAVs as methods of delivering goods quickly and efficiently. Overall, UAVs have the potential to revolutionize the delivery industry by providing a faster, more efficient, and cost-effective means of delivering goods. However, the technology is still relatively new and there are many regulatory and technical challenges that need to be addressed before UAVs can be widely used for delivery services [159]. Implementing UAV IoT applications requires a combination of technologies, such as sensors, communication systems, and data analytics. However, the potential benefits of UAV IoT applications, including improved efficiency, reduced costs, and increased safety, can have a significant impact on multiple industries.

#### 1. Last-mile delivery:

UAVs can be used to deliver packages to customers' doorsteps [160] or other inaccessible locations in the last mile of the delivery process, reducing the time and cost of delivery [161]. UAVs offer a number of advantages over traditional methods, such as ground-based delivery and car-based delivery, including speed, accuracy, and efficiency.

2. Medical supply delivery:

UAVs can be used to transport medical supplies such as drugs, blood, and vaccines to hospitals or other medical facilities in emergency situations or in hard-to-reach areas [160,162]. The benefits of using UAVs to deliver medical supplies include saving lives, reducing costs, and increasing efficiency.

#### 3. Retail delivery:

UAVs can be used to transport products from warehouses or distribution centers to retail stores, improving the efficiency of the supply chain [163]. The benefits of using UAVs for retail delivery may include increased customer satisfaction by delivering products faster, reducing delivery cost, and improving environmental impact [164].

4. Parcel delivery:

UAVs can be used to transport parcels of various sizes and weights, including small parcels for individual customers and larger parcels for businesses [161]. Overall, the use of UAVs for parcel delivery is still in its early stages. However, the potential benefits (e.g., speed, and accuracy) of this technology could make it a viable option for the future of parcel delivery.

### *2.10. Robotics*

Robotics can affect our daily routine by improving our quality of life, conserving the budget, and minimizing expenditure. Nowadays, robots are intelligent machines and capable of interacting with other robots as well as human beings. Robotics has the potential to revolutionize various aspects of smart cities [165] by enhancing efficiency, safety, and sustainability. Robotic systems are increasingly being integrated with IoT technologies to enhance their capabilities and create new applications [166,167].

#### 2.10.1. Automated Transportation

Autonomous vehicles and drones can be integrated into a city's transportation system, providing efficient and safe mobility solutions. Self-driving cars can reduce traffic congestion and emissions, while drones can be used for deliveries and surveillance [168].

#### 2.10.2. Infrastructure Maintenance

Robots can be deployed to inspect and maintain critical infrastructure such as bridges, roads, and utility lines. They can quickly identify and repair issues, reducing downtime and improving infrastructure permanence [169].

#### 2.10.3. Surveillance and Security

Robots equipped with cameras and sensors can monitor public spaces, enhancing security and surveillance in the city. They can patrol streets, parks, and other areas, detecting suspicious activities and helping law enforcement respond quickly to potential threats [170].

#### 2.10.4. Environmental Monitoring

Robots equipped with sensors can monitor air and water quality, noise levels, and other environmental factors to provide real-time data for pollution control [171]. Environmental monitoring robotics is a rapidly growing field. As technology continues to develop, robots will become increasingly capable of collecting data and monitoring the environment in ways that were not possible before. This data can be used to improve our understanding of the environment and to develop better ways to protect it.

#### 2.10.5. Agriculture and Urban Farming

In smart cities, rooftop gardens and vertical farms are becoming more popular. Robots can be used to automate planting, watering, and harvesting, ensuring sustainable and efficient food production. Robots can monitor crops and soil conditions. The sensors can measure factors such as temperature, humidity, soil moisture, and nutrient levels, which can be used to optimize crop growth and reduce water and fertilizer usage [172].

#### 2.10.6. Healthcare Assistance

Robotics can assist in healthcare applications, such as delivering medications and supplies in hospitals or supporting elderly and disabled citizens with daily tasks in smart homes. Robotics IoT applications in healthcare include robotic assistants for surgery, patient monitoring, and medication management. These robots can be equipped with sensors to monitor vital signs and provide real-time feedback to healthcare professionals [173].

#### 2.10.7. Disaster Response

In the event of natural disasters or emergencies, robots can be deployed for search and rescue operations, providing critical assistance to first responders, and minimizing human risk [174]. Despite the challenges, disaster response robotics is a promising field with the potential to save lives and improve the efficiency of disaster response. As technology continues to develop, robots are likely to play an increasingly important role in disaster response.

#### 2.10.8. Education and Entertainment

Robots can be used in educational settings, offering interactive learning experiences. Additionally, they can be utilized in public spaces for entertainment purposes, like interactive art installations or robot-guided tours [175]. Educational and entertainment robots are becoming increasingly popular. They offer a fun and interactive way to learn about STEM concepts and to experience the latest in robotics technology.

### 2.10.9. Tourism

In smart cities, robots can act as tour guides, providing information about landmarks, historical sites, and tourist attractions [176]. Robotics is still a relatively new technology in the tourism industry, but it has the potential to revolutionize the way that tourists interact with destinations. Robots can provide a more personalized and engaging experience for tourists, and they can also help to reduce costs for businesses.

#### 2.10.10. Smart Home Assistants

Domestic robots can help residents in their homes by performing household routines, managing appliances, and providing reminders and assistance to the elderly and disabled [177].The benefits of using smart home assistants and robotics in the home may comprise the following: convenience, security, and entertainment. However, there are also some potential drawbacks to using smart home assistants and robotics in the home: privacy, security, and cost.

#### **3. Smart City Communication Systems**

Due to the massive volume of sensors and their data, robust connectivity technology is a prerequisite for success coverage and reliability across the entire city is the key to launching any successful smart city [3,88]. Because cabling a massive number of sensors and smart IoT devices is cost prohibitive, wireless technology is the key and sole viable solution to the deployment of IoT networks across the city [88]. There is an emerging consensus that current fourth generation (4G) long term evolution (LTE) and current 5G are the key technological candidates that can provide the required global IoT connectivity to such a staggering number of "things" in a city [3,5,12]. Cellular-based machine-to-machine (M2M) communications is one of the key IoT-enabling technologies with huge market potential for cellular service providers deploying LTE networks [178].

4G and/or 5G cellular technologies can support a wide range of current and future smart city applications and services including video surveillance for public safety, intersection safety analytics (pedestrian safety), traffic management, traffic light controls, digital signage systems, EV charging, public Wi-Fi and much more [3,5,12,179]. Smart city IoT applications span a wide range-of-use cases ranging from mission-critical applications (e.g., traffic control, emergency response, video surveillance, and connected vehicles), which require ultra-reliability and ultra-low latency, to those that require support of a massive number of connected M2M devices with relaxed latency and reliability requirements (e.g., smart meters) [3,14].

There are numerous current competing solutions that can support network connectivity for such a wide range of IoT applications [3]. These solutions span a wide range-of-use cases ranging from relatively low cost and easily deployable solutions for basic services to the most expensive, high-performance systems suitable for the most demanding requirements [14].

Most massive scale deployment of IoT applications, however, requires low-cost devices that communicate infrequently, with a low data rate and low energy consumption so that they can deliver an extremely long ten-year battery life as well as good coverage [3]. This is where low-power wide area networks (LPWAN) technology is needed. LTE-M (LTE for machines) and narrowband IoT (NB-IoT) are the first cellular-based LPWAN technologies standard supporting massive IoT applications [180].

These simpler and lower cost cellular LPWA technologies support longer battery life (up to 10 years) and better coverage (for IoT devices underground and deep inside buildings) compared to traditional M2M-IoT cellular connectivity options. Though LP-WAN technologies have clear advantages over traditional IoT cellular connectivity options, they are only suited to meet very basic data requirements for IoT applications with limited/modest data needs and relaxed latency (in the order of few seconds) [3,181]. They are ideally suited for IoT applications, which require just extended coverage, but reliability, latency, and availability might be more or less important [181] as shown in Table 1.


**Table 1.** Summary of Communication technologies support in the Smart City.

#### *3.1. Low Power Wide Area Networks (LPWANs)*

LPWAN technologies are a group of wireless technologies that are designed to provide long-range, low-power connectivity for IoT devices. LPWAN technologies are ideal for applications where battery life [3] is critical, such as smart metering, asset tracking, and environmental monitoring. Here are some of the most popular LPWAN technologies:

#### 3.1.1. LORAWAN

LORAWAN (long range WAN) is a widely adopted LPWAN technology that enables long-range communication at low data rates [182]. It operates in unlicensed frequency bands, making it available for public use without the need for expensive licenses.
