## 3 5G and TSN Integrated Networks for VPP
### QoS Mapping between TSN and 5G of VPP Traffic  
The primary problem of VPP traffic transmissions in the 5G and TSN integrated network is performing the mapping of VPP traffic between the TSN and the 5G networks. Since different QoS frameworks are used in 5G and TSN networks separately, a reasonable QoS mapping rule needs to be designed in the coordinated scheduling process. The QoS mapping rule is utilized to map VPP traffic to TSN traffic classes and 5G QoS identifiers (5 QI). To guarantee the delay and reliability of VPP traffic, correct and appropriate mapping is indispensable.  
In the 5G and TSN integrated network, the 5G network communicates with the TSN centralized network configuration (CNC) in the control plane through the TSN application function (AF) module. TSN AF completes the mapping and interworking of the network configuration and management information. AF not only has a bridging capability, but it also converts the scheduling provided by the CNC to the 5G system. AF identifies the MAC address of the device-side TSN translator (DS-TT) of the corresponding protocol data unit (PDU) session, and it obtains the relevant TSN characteristic parameters of VPP traffic. After AF receives the TSN characteristic parameter information, it sends the information to the 5G policy control function (PCF). The PCF is responsible for mapping these TSN characteristic parameters to the 5G QoS parameters, generating a 5 QI mapping table and sending it to the session management function (SMF). Then, the SMF configures the QoS parameters. On the user plane, VPP traffic is converted into the corresponding 5G QoS flow through the TSN translator. It configures the forwarding mechanism according to the mapping rules provided by the PCF.  
In 5G networks, the SMF is responsible for controlling the QoS. When establishing a PDU session, the SMF configures the corresponding QoS parameters for the radio access network (RAN), including QoS configuration information such as 5 QI and ARP (assign and retain priority). The 5 QI value is standardized, including QoS characteristics such as packet delay budget, resource type, and priority. Priority indicates the criticality of the scheduling of the QoS flow. In 5G networks, different flows are identified through their SQIs.  
This paper adopts a static mapping strategy based on the traffic characteristics (priority, delay, reliability, etc.) of VPP traffic. Various types of VPP traffic are mapped to corresponding TSN traffic classes and 5 QIs. In the 5G network, the 3 GPP standardized 5 QI to QoS feature mapping table [39] is referred to for the mapping procedure. In the 5 QI standardized QoS feature mapping table, resource types are divided into delay-critical guaranteed bit rate (GBR), GBR, and non-GBR types. The GBR type is applicable to the traffic with high real-time requirements, and it can guarantee the bandwidth of the PDU session. Fast frequency regulation traffic, regular frequency regulation traffic, emergency demand response traffic, and normal demand response traffic have low delay (millisecond level) and bandwidth requirements, so they need to be mapped to the GBR type. Among them, fast frequency regulation traffic, regular frequency regulation traffic, and emergency demand response traffic have the lowest delay and the highest reliability requirements, which are mapped to the delay-critical GBR. The delay in the peak regulation traffic and power trade market traffic is of seconds, and they have low bandwidth and reliability requirements. They use the non-GBR resource type for transmissions. The non-GBR resource type is used for services with low real-time requirements. It needs to bear the requirement of reducing the rate in case of network congestion. A static mapping table based on traffic characteristics is shown in Table 2.