## 2 Related Works  
### Research on DSRC and C-V2X  
In recent years, many scholars have performed much research to improve DSRC and C-V2X. Particularly, in 2019, the IEEE research group proposed IEEE 802.11 bd to update IEEE802.11p. IEEE802.bd will realize vehicular communication with a relative speed of 500 km/h, while the communication distance will be extended to 2000 m [23]. With the development of 5G, 3 GPP proposes NR-V2X on the basis of LTE-V2X so that it can use the advanced technology and spectrum resources of 5G [24].  
In [25], [PERSON] et al. proposed a routing mechanism based on DSRC to improve the network response time and bandwidth utilization. In this method, a machine learning method is used to predict the future state of the vehicles to optimize the communication link to reduce the delay. Many other scholars have integrated DSRC and C-V2X, and designed a mechanism to use these two communication methods simultaneously. In [14], [PERSON] et al. proposed a QoS-aware relay algorithm in a scenario where some vehicles used DSRC and some vehicles used C-V2X, which allowed vehicles using two different communication technologies to successfully network and complete information transmission. In [15], [PERSON] et al. proposed a DSRC and C-V2X hybrid vehicle network architecture and protocol stack and designed a distributed radio resource management entity that could effectively manage and coordinate radio resources in both RTAs. In [16], [PERSON] et al. proposed an adaptive semi-persistent C-V2X and DSRC hybrid vehicle networking model called H-V2X. In this model, when C-V2X meets the performance index, C-V2X is used for data transmission, otherwise, DSRC is used for data transmission. [PERSON] et al. proposed a routing mechanism called TDCR in [13], which realizes the hybrid application of DSRC and C-V2X under consideration of the balance between the QoS requirements of different traffic and communication costs of users. In [17], [PERSON] et al. realized a hybrid framework with C-V2X as the main communication means and DSRC as a blind-compensation communication measure. In this work, V2V communication is also used to enhance cellular network base station signals. Since the two communication standards, DSRC and C-V2X, have conflicts in the 5.9 GHz frequency band, how to make two different new technologies work together in the same frequency band has also become an important research topic. [PERSON] solved the problem of DSRC and C-V2X sharing in the 5.9 GHz band in [26], which enables DSRC and C-V2X to transmit data concurrently under the same framework.  
In addition to making vehicular communication more efficient and reliable, how to allocate the resources of the communication system also has a crucial role in the performance of vehicular communication. In [27], [PERSON] et al. proposed an auction mechanism combined with blockchain technology, which maximizes social welfare and optimizes the allocation of communication resources on the Internet of Vehicles. In [28], [PERSON] et al.  
proposed a multi-type and multi-resource auction mechanism, which greatly improves resource use efficiency. The mechanism has significance in promoting the progress of communication resource allocation in vehicular communication systems.  
Research in the field of vehicle communication has made great progress. However, there are few considerations concerning the user level in the existing results, and the high throughput and low latency requirements for CAVs are still not fully met.