# Privacy Framework for the Development of IoT-Based Systems
## 5 Proposed Methodological Approach: Planning, Requirements, and Design (PRD)
### Phase 2: Gathering of Requirements  
Once the Business Report is approved, Phase 2 begins. With a comprehensive understanding of the business context, both functional and non-functional requirements are defined. FRs specify the core tasks and services that the system must perform, detailing the essential operations and features needed to meet user needs. In contrast, NFRs outline the system's quality attributes, technical standards, and design constraints that do not directly relate to functionality but are crucial for overall system performance. These include factors such as security protocols, scalability, system update methods, and regulatory compliance.  
This phase follows a top-down approach, structured according to the IoT-OSRM reference model, beginning at the business level and systematically moving downward toward the \"things\" layer. To collect and document critical information, developers utilize various techniques, such as interviews, case studies, and stakeholder consultations. The gathered requirements are then categorized into the six levels outlined in Figure 2, ensuring a structured approach to system design and implementation:  
* **Level 1--Sensor/Actuator Node:** Focuses on the selection of hardware components, including sensors, actuators, microcontrollers, memory, and processing units. Additional key considerations include the integration of edge/fog computing and local data processing to enhance system responsiveness and reduce network load.
* **Level 2--Connectivity:** Specifies the type of connection between the \"things\" and the border element, whether wired, wireless, or hybrid. Developers evaluate variables such as cost, scalability, environmental conditions, bandwidth, and reliability to determine the most effective communication method.
* **Level 3--Border:** Defines the \"border element\" that connects the system to the Internet and facilitates communication between IoT devices. This level may incorporate technologies such as network virtualization, middleware, and software-defined networks to optimize data flow and improve network efficiency.
* **Level 4--Storage:** Determines the most appropriate data storage method, considering options such as cloud-based, on-premises, or hybrid solutions. Key factors include data security, redundancy, scalability, and accessibility to ensure efficient data management and compliance with privacy regulations.  
* **Level 5--Abstraction:** Identifies the processes through which raw data is transformed into meaningful information. This level leverages expert knowledge and advanced AI analytical techniques, such as ML and data mining, to interpret and contextualize complex data streams.
* **Level 6--Display:** Defines how information is presented to end users, focusing on intuitive and accessible formats, such as tables, graphs, and notifications. Effective data visualization at this level enhances user engagement and decision-making.  
Given the complexity of IoT ecosystems, no single tool can fully ensure security and privacy. Therefore, a comprehensive, multi-layered approach is required, integrating diverse techniques and defining privacy guidelines at each level to address specific security challenges and compliance requirements.  
At the conclusion of this phase, a detailed Requirements Report is compiled, documenting all functional and non-functional requirements. This report undergoes thorough review and validation by project stakeholders, including managers and developers. If approved, the project proceeds to Phase 3. If not, a revision cycle is initiated to address any outstanding issues or gaps before moving forward.