p-持续CSMA协议下，一个用户在发送之前，先侦听信道，若是空闲，就以概率p发送出去，而以q =1-p的概率推迟到下一帧时。如果下一帧时仍是空闲，便再次以概率p发送而以q推迟到再下一帧时。直到发送成功或另外一用户开始发送时为止。若一开始就侦听到信道忙，它就等到下一帧时，然后再开始上述过程。若发生冲突，这等待一随机时间后重新开始。本实验中取q值为0.5。求的是0.5-持续CSMA。 -p-persistent CSMA agreement, a user before sending the first interception channel, if idle, with probability p sent, and to q = 1-p probability postponed to the next frames. If the next frame was still idle, they again sent with probability p and q to further postponed to the next frames. Until this a success or other users at the beginning of this date. If an interception at the start of the busy channel, it will wait till the next frames, and then begin the process. If conflict breaks out, waiting for a random period of time after the re-start. The experiments take q value of 0.5. For the 0.5-sustained CSMA.