## 2 Methodology
### Problem Statement  
The creation and evolution of smart city applications have encountered significant hurdles attributed to the extensive set of devices involved. Several design challenges face the evolution and development of smart cities; Figure 3 presents the main categories of these challenges. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Category** & **Area** & **Keywords/Strings** \\ \hline \multirow{4}{*}{A} & \multirow{4}{*}{Smart city} & A1—Smart city \\  & & A2—Smart city applications \\  & & A3—Smart city challenges \\  & & A4—5G use cases \\  & & A5—Sustainable development \\ \hline \multirow{4}{*}{B} & \multirow{4}{*}{Key technologies} & B1—Key technologies of future smart cities \\  & & B2—SDN for smart city networks \\  & & B3—Benefits of deploying SDN for smart city networks \\  & & B4—Challenges with SDN-based smart cities \\  & & B5—NFV for smart cities \\  & & B6—Challenges with NFV \\  & & B7—Mobile edge computing for smart city applications \\  & & B8—Challenges with MEC \\  & & B9—Internet of things-based smart cities \\  & & B10—Internet of things connectivity \\  & & B11—Challenges with IoT-based smart cities \\  & & B12—Fog computing for smart cities \\  & & B13—Challenges with fog-based smart cities \\  & & B14—Blockchain for smart city applications \\  & & B15—AI-based smart cities \\  & & B16—Benefits of deploying AI for different smart cities \\  & & B17—Challenges of implementing AI for smart cities \\  & & B18—Smart city datasets \\ \hline \multirow{4}{*}{C} & \multirow{4}{*}{Applied research} & C1—Smart healthcare \\  & & C2—Smart parking \\  & & C3—Smart city networking \\  & & C4—MEC-enabled smart city \\  & & C5—Fog-enabled smart city \\  & & C6—Smart grid \\  & & C7—Smart homes \\  & & C8—Smart city networking \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main categories of keywords and index terms. These groups of challenges are summarized as follows [13; 14; 15; 16]:  
1. Cost of operation: All organizations depend on innovations for managing data, such as cloud storage and virtualization, but these innovations provide higher costs because of the rapidly rising amount of data. New technologies and high-level software and hardware tools are needed to develop efficient solutions; therefore, smart city operators strive to create effective solutions through cost-effective strategies. 2. Numerous devices: Smart cities require numerous sensors to collect data from various aspects of urban life. These sensors play a crucial role in transforming cities into intelligent, data-driven ecosystems. The proliferation of numerous devices in smart city development poses significant issues that should be handled to ensure smart cities' effective and sustainable implementation. Communication networks of smart cities are anticipated to support dense deployment, which introduces many constraints on the design and development of such networks. These constraints include data management, ensuring coverage requirements, achieving network availability, and managing the communication overhead. Ensuring seamless communication and integration among numerous and heterogeneous smart city devices requires standardized interfaces and protocols. 3. Scalability: Network scalability refers less to the quality of the network than to its efficiency and capacity to accommodate growth with little impact on performance. The scalability of a network is measured by its ability to accommodate the growing number of users, devices, or services without degrading overall performance. For a network to expand effectively, it must maintain its efficiency, even as its capacity or resources increase. As the network grows to meet rising demand, it is important that its performance stays steady or even improves. Large businesses, data centers, cloud infrastructure, and telecommunications networks are just a few examples of settings where expansion is expected, making scalability a crucial factor in network design. 4.