## 7 CPS Architecture in GBG-RPL  
The CPS architecture in the proposed methodology comprises several interconnected layers that facilitate communication and coordination between physical and cyber components, as shown in Figure 5. A high-level representation of the architecture is given below:  
1. Sensing Layer: The sensing layer serves as the core of the CPS architecture. It is made up of a number of sensors and actuators that are placed throughout the physical environment (e.g., smartwatches and fitness bands) to gather information from the patients [90]. The sensors record critical data from the patients related to location/motion, blood pressure, heartbeat, and sugar levels for central monitoring. The actuators interact with the physical world by carrying out operations according to commands from the cyber system (e.g., implantable devices like pacemakers and insulin pumps function as adjusted by the practitioners).
2. Communication Layer: Data transmission between the sensing layer (devices on the patients) and the cyber layer (servers and central control/monitoring at hospitals) is carried out by the communication layer [91]. It consists of networks, gateways, and communication protocols that make it easier for data to be sent from sensors and actuators to cyber components for analysis and decision making.
3. Cyber Layer: The cyber layer applies control algorithms, data analytics, and decision-making procedures to the data it receives from the sensing layer. This layer consists of computer hardware such as edge servers, cloud servers, and control systems that process the incoming data to produce useful insights and coordinate the operations of the physical layer [92].
4. Data Analytics and Control Layer: Data analysis and thoughtful decision making are the main functions of this layer [93]. This layer processes the raw data gathered from the sensing layer to discover useful patterns and make informed decisions.
5. User Interface and Interaction Layer: Users can interact with the CPS system through the user interface layer [94]. Applications, dashboards, and visualizations are included that let users control parameters, monitor system performance, and input data to adjust the function of the CPS device.
6. Security and Privacy Layer: The safety and privacy of the CPS must be guaranteed at all costs. This layer protects the CPS against online threats and unauthorized access through a variety of security methods, encryption protocols, access-control systems, and authentication procedures [24].
7. Integration and Interoperability Layer: CPSs frequently require the integration of several parts and systems from diverse vendors. Smooth coordination inside the CPS system is made possible by the integration and interoperability layer, which enables seamless communication and cooperation between these many components [95]. In the proposed methodology, the device ID along with the trust parameters are stored in the device acquirer and blockchain-based revised global trust list (BRGTL).
8. Feedback and Adaptation Layer: This layer contains feedback loops and adaptive control systems that let the CPS devices react quickly to commands given by the central control/monitoring systems [96].