## 3 System Design  
### Overview  
Figure 1 shows the schematic of our proposal applied in a real environment. It has a general design that performs positioning using UWB in a local network environment consisting of a server, anchors, and tags, and this reflects the intention to minimize the cost of infrastructure modification due to the application of a new technology. To list the differ  
ences, firstly, our proposal utilizes an improved localization technique. When measuring location based on distance, multiple distance values and fixed coordinates of the anchor are used as the inputs. These inputs have default errors and can cause significant distortion in noisy environments. These changes in input values can be a factor that significantly reduces the quality of positioning. We solved this problem by improving the conventional positioning method. Second, our proposal designs a new positioning system using a DAG-based distributed ledger. In vehicle networks comprised of manned/unmanned aerial vehicles, excellent positioning techniques are essential for accurate position measurement, and it is very important to protect the system from malicious attacks such as forgery and falsification, which can significantly reduce the accuracy of position measurement. Typically, high levels of security incur significant overhead in networking and computation. On the other hand, positioning systems require high real-time performance. In short, positioning performance and system safety are a trade-off. In summary, the security technology applied to the positioning system must satisfy both low system overhead and excellent safety. For this reason, this paper applied a DAG-based distributed ledger with improved consensus to the positioning system. Based on the two new proposals mentioned above, we ultimately propose a complete localization framework. Our proposed localization framework provides a positioning system based on trust. All the positioning nodes operate as participants on the DAG-based distributed ledger. This means that transactions containing data necessary for positioning are created, verified, and confirmed according to a consensus, and transaction information is distributed throughout the network. Figure 2 shows the system architecture of the proposed localization framework. The description of the components can be listed as follows:  
* The **device layer** is a device abstraction layer that generalizes resources for the purpose of managing and controlling the resources available in the framework. This method reduces the development costs for heterogeneous devices and provides an intuitive interface to the users. * The **P2P network layer** manages P2P connections between nodes and defines security-related tasks. * The **service layer** verifies the transaction information collected through the network and records it in the ledger. The recorded transaction includes not only the UWB sensor data, but also the details of the devices participating in the network, such as the device ID and status information, and based on this, the main services such as generating the location information of the target devices and generating device metadata are operated. * The **application layer** includes the implementation of various functions through the API, such as the framework's positioning service, device control, and distributed ledger  
Figure 1: This is a system schematic of the proposed localization framework with a distributed ledger. query. Based on this, it provides various positioning services to the users and useful functions necessary for positioning developers to develop their own technologies. At the device layer, the data for positioning are generated in real-time by positioning devices such as UWB sensors. Not only that, the data necessary to operate various services along with the location information, such as the device status information and actuator information, are generated. The proposed framework manages all these data as transactions and transmits them to the P2P network.