## 3 Cooperative Perception Information-Sharing
### The Effect of Network Performance on Cooperative Perception
#### 3.3.3 Congestion Control  
The decentralized congestion control (DCC) mainly focuses on solving the problem of channel congestion in cooperative perception information sharing and improving the timeliness and accuracy of cooperative perception information. Currently, DCC technology mainly reduces the congestion of the communication channel by adjusting the generation strategy of cooperative sensing information and controlling the transmission parameters. Among these, adjusting the generation strategy of cooperative perception information mainly reduces the redundancy of cooperative perception information by optimizing the message generation rules. The most common control parameters are transmission rate control, transmission power, and transmission data rate control [96]. The safety-critical application of autonomous driving has strict constraints on the delay, and the time interval delay between the generation and transmission of cooperative perception cannot exceed 100 ms [82]. The pros and cons of communication performance have a direct impact on the effectiveness of cooperative perception, which, in turn, interferes with the execution of decision-making and control modules [97; 98]. When the communication delay and data PLR in the communication process reach a certain level, it will have a great negative impact on the use of V2X information in autonomous driving, resulting in a poor cooperative perception effect, which, in turn, reduces the safety of autonomous driving. In order to analyze and reduce the negative impact of delay and PLR on network performance, and, thus, improve the effectiveness of cooperative perception, domestic and foreign scholars have carried out much research on this. [PERSON] et al. [99] constructed several typical IoV application scenarios in a closed test field environment for the needs of DSRC test evaluation. The experiment used PLR and delay as evaluation indicators and tests and analyzed the effects of speed, distance, shelter, and other factors on the performance of DSRC. The test results show that communication distance and obstacle occlusion are the main factors that cause the degradation of DSRC communication performance. Obstacle occlusion increases the PLR of communication, resulting in security information not being fully transmitted under NLoS conditions, reducing the effectiveness of cooperative perception. Similarly, [PERSON] et al. [100] designed and implemented a performance evaluation of DSRC communication in both Line-of-sight (LoS) and NLoS scenarios in real scenarios. When the transmission power is 5 dBm and the packet reception rate exceeds 90%, the communication distances in the LoS and NLoS test scenarios are 720 m and 175 m. When the transmission power is 11 dBm and the packet reception rate exceeds 90%, the communication distances in the LoS and NLoS test scenarios are 1035 m and 515 m. Through comparative analysis, communication distance and occlusion can have a certain impact on the packet reception rate, which, in turn, affects the effectiveness of perception. [PERSON] et al. [101] used performance indicators such as PLR, latency, and throughput to evaluate the performance of communication devices under high channel occupancy in dense traffic scenarios. They proposed that a high channel occupancy rate will obviously lead to a decline in vehicle communication capabilities and cannot fully guarantee the effective transmission of cooperative sensing data. [PERSON] et al. [102] comprehensively considered the impact of packet loss and delay on V2X data fusion, implemented automotive augmented reality by integrating V2X communication and information from the vehicle itself, and evaluated the impact of sensor fusion with packet loss and delay [103]. In the experiment, when the packet loss in the lossy network was set to 5% and the delay was 1 s, the accuracy of data fusion was nearly doubled compared to normal.