根据第二章的叙述我们知道，工作在SCH信道上的车辆如果有非交通安全消息

According to the narrative in Chapter 2, we know that if a vehicle working on the SCH channel has a non-traffic safety message sending request, it first obtains the right to use the channel according to the binary exponential backoff mechanism. Once the channel usage rights are obtained, the estimated transmission time of the first data frame of the current MAC layer queue can be estimated according to the current physical layer rate

According to the narrative of Chapter II, we know that when a vehicle working on a SCH channel has a request for a non-traffic safety message, it first obtains the right to use the channel according to the binary index retreat mechanism. Once channel usage is granted, the estimated send time for the first data frame of the current MAC layer queue can be estimated based on the current physical layer rate

According to the second chapter, we know that if the vehicle working on the SCH channel has a non traffic safety message to send a request, it first obtains the right to use the channel according to the binary exponential backoff mechanism. Once the channel usage right is obtained, the estimated transmission time of the first data frame in the current MAC layer queue can be estimated according to the current physical layer rate<br>