# Intelligent Computation Offloading Based on Digital Twin-Enabled 6G Industrial IoT
## 3 System Model  
### DT-Enabled Network Model  
The proposed digital twin-enabled network architecture is shown in Figure 1, which is composed of three main elements:  
1. The bottom physical device network includes client devices in the IIoT, such as smart machines, sensors, vehicles, and IIoT devices. It also contains devices such as switches, access points, and databases that assist communication between devices. Sensors collect data from the industrial field environment and connect to the nearest AP according to the network topology. Cells led by AP are scattered throughout the whole work region, operated for monitoring and control among the machines and the robots.
2. The edge server element acts as a bridge between the network of physical devices and the digital twin. Digital twin networks are built and maintained with the help of edge servers. They are also the key to achieving virtual-physical interactions. The edge server element connects the network service application and the physical devicenetwork through standardized interfaces, completes the real-time information collection and control of the physical network, and provides timely diagnosis and analysis. We can complete the digital modeling of the factory communication environment before the transmission of data, and then simulate the transmission in the virtual digital space to evaluate the frequency allocation and channel tolerance. We can also import additional traffic data to evaluate whether the transmission scheme can meet the requirements of the service.
3. The digital twin network can predict the optimal transmission channel through continuous acquisition and intelligent analysis of field data. A digital twin system can be roughly divided into three modules according to the functions it can achieve.  
The modeling function module should precisely digitize physical space and realize the virtual-real interaction between the physical entity and the digital model through the edge gateway. At this stage, the transmission of data does not necessarily need to be completely real-time. Data can be collected locally and transmitted periodically in a short period. The core technology of this module is replication modeling and IoT device sensing technology. Through sensing, mapping, and process modeling, the system can recognize the physical objects, complete the digitization of physical objects, and build the corresponding mechanism model.  
In the simulation functional module, the system can create a virtual replica of the physical entity according to the actual application requirements. The DT analyzes and understands the data involved, and tests, alerts, and adjusts problems that have occurred or are about to occur. This function can realize the status tracking, analysis, and problem diagnosis of the physical space. This module focuses on building a global operational model based on data from the digital twin without transferring the raw local data.  
The optimizing function module combines the results of the model operation with the dynamic system operation for self-learning and updating. This module predicts, simulates,  
Figure 1: Digital twin-enabled network architecture.  
and debugs potentially undiscovered and future new modes of physical space in digital space based on known modes of physical space operation. After establishing the prediction of future development, the digital twin will present the prediction content in the digital space in a way that can be understood and perceived. This module has the function of active learning. Based on the learned existing knowledge, the system deduces unknown knowledge. The core technologies involved are concentrated in the fields of machine learning, image recognition, big data analysis, etc.  
The digital twin-enabled network architecture brings obvious efficiency gains and cost reductions to industrial manufacturing. With the support of 6G technology, closer connections can be established between edge servers and physical terminals. This also means that more data will be collected and aggregated.