## 2 IoTMADLab and Methodology
### IoT Network Reference Architecture
#### 2.3.1 Data Model  
The data model defines the logical structure of the information associated with an asset monitoring, management, and control application such as a city's public lighting system. It can also define the protocols for accessing and communicating this information. To ensure the interoperability of the systems that make up the application and to avoid dependence on a single vendor lock-in, the data model must be based on open specifications standardized by independent entities not affected by commercial interests.  
After analysing different approaches, the IoTMADLab has decided to align with the uCIFI data model [31]. The uCIFI alliance is an open, not-for-profit organization whose goal is to develop open standards for enabling device interoperability of devices in Smart City applications. The uCIFI data model defines the use of four protocols: LwM2M, IPSO, CoAP, and CBOR.  
* LwM2M (Lightweight M2M), promoted by the Open Mobile Alliance (OMA), is a protocol designed for efficient management of IoT devices, providing standardized communication and data exchange. It enables remote device management, firmware updates, and monitoring, optimizing IoT deployments. LwM2M's lightweight nature  
Figure 1: IoTMADLab IoT network reference architecture: the focus is put at the network and data model layers (green-colored box). For the data model layer, we use the uCIFI model, while for the network layer, initially Wi-SUN mesh technology is proposed.  
ensures compatibility with resource-constrained devices, enhancing scalability and interoperability in IoT ecosystems. This protocol streamlines device management processes, facilitating seamless integration and operation of IoT networks [32].
* The IPSO (Internet Protocol for Smart Objects) Alliance provides a framework for interoperability among IoT devices, defining common data models and communication protocols. By standardizing data representation and exchange, IPSO simplifies device integration and application development in IoT ecosystems. It facilitates seamless interoperability between heterogeneous devices, fostering scalability and innovation. IPSO's approach enhances efficiency and reliability in IoT deployments, promoting the widespread adoption of smart technologies [33].
* CoAP (Constrained Application Protocol) is a specialized web transfer protocol designed for constrained IoT devices, offering lightweight communication with low overhead and high efficiency. It enables devices to exchange data over the internet in a constrained environment, optimizing resource usage. CoAP's simplicity and flexibility make it ideal for IoT applications, supporting reliable, asynchronous communication and resource discovery [34].
* CBOR (Concise Binary Object Representation) is a compact data serialization format derived from JSON, designed for resource-constrained devices in IoT applications. It efficiently encodes complex data structures into binary form, reducing payload size and transmission overhead. CBOR's simplicity and efficiency make it suitable for constrained environments, facilitating seamless data exchange between devices and applications [35].