# Metaverse Architectures: A Comprehensive Systematic Review of Definitions and Frameworks
## 2 Methodology
### Thematic Analysis
#### 2.2.4 Architectural Model Categorisation  
A thematic classification was applied to analyse the 25 metaverse architecture studies identified through the systematic literature review. These architectural models were organised into three high-level categories based on their design focus and conceptual framework:  
* Technology-Based Architecture: These models are built upon the convergence of key technologies that facilitate metaverse capabilities, including blockchain, artificial intelligence, digital twins, 5G/6G networks, and edge computing. The classification is based on the pivotal role of enabling technologies in shaping architectural layers or components. Research in this area investigates how technological frameworks underpin interoperability, scalability, or decentralisation within metaverse environments.
* Domain-Based Architecture: These models are specifically designed for particular sectors, such as healthcare, education, or manufacturing. The classification criterion is the use of metaverse architecture to address domain-specific functional requirements. These architectures often feature customised components, such as the doctor/physician environment [57], smart manufacturing layer [65], or industrial application layer [66], and include considerations for ethical, regulatory, or contextual factors. They do not always follow a uniform structure but are tailored to meet the needs of their target domain.  
\begin{table}
\begin{tabular}{p{85.4 pt} p{85.4 pt} p{85.4 pt} p{85.4 pt}} \hline \hline
**Category** & **Primary Focus** & \begin{tabular}{c} **Representative** \\ **Concepts** \\ \end{tabular} & **Linked Themes** \\ \hline Technological Orientation & \begin{tabular}{c} Foundational systems and infrastructure \\ \end{tabular} & \begin{tabular}{c} AI, VR/AR, \\ blockchain \\ \end{tabular} & \begin{tabular}{c} Technological \\ Enablers, \\ Interconnectivity \\ \end{tabular} \\ \hline Spatial-Environmental Design & \begin{tabular}{c} Virtual environments and spatial design \\ \end{tabular} & \begin{tabular}{c} Immersion, digital \\ twins, persistence \\ \end{tabular} & \begin{tabular}{c} Immersion, \\ Persistence, \\ Representation \\ of Reality \\ \end{tabular} \\ \hline Social and Human Interaction & \begin{tabular}{c} User presence and \\ community \\ engagement \\ \end{tabular} & \begin{tabular}{c} Avatars, collaboration, \\ presence \\ \end{tabular} & \begin{tabular}{c} Social Engagement, \\ Multidimensional Activities \\ \end{tabular} \\ \hline Economic and Ownership Systems & \begin{tabular}{c} Digital economies \\ and virtual value \\ systems \\ \end{tabular} & \begin{tabular}{c} NFTs, monetisation, \\ ownership \\ \end{tabular} & \begin{tabular}{c} Economic Systems, \\ Multidimensional Activities \\ \end{tabular} \\ \hline Conceptual and Linguistic Constructs & \
\begin{tabular}{c} Etymology, abstract \\ definitions, theory \\ \end{tabular} & \"Meta+verse\", conceptual synthesis &
\begin{tabular}{c} Representation of \\ Reality, \\ Interconnectivity \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 3: Categorisation of metaverse definitions by conceptual focus and linked themes.  
* Layered-Based Architecture: These models utilise a structured, frequently multi-layered paradigm to articulate the essential components of the metaverse. Designed to encapsulate the extensive scope of metaverse systems within a universally applicable structure, they facilitate broad utility across disparate domains. They feature stack-based or modular designs that show how technologies, services, and user interfaces relate.  
This categorisation was developed through inductive pattern recognition, examining recurring structural motifs, design intentions, and terminologies across studies. Thematic groupings were then created based on observable design logic. In contrast to the conceptual definitions, the architectural models were not evaluated against the eight previously established thematic themes. Instead, they were classified solely based on their structural and domain-specific focus.