杭州电子科技大学通信工程计算机网络实验报告2.doc

计算机通信与网络实验报告姓 名：徐 一 得 学 号 班 级：通信五班 上课时间：周四3-5 实验名称：Simulation on Performance of Data Link Control Protocols实验目的Realizing the principles of Data Link Control Protocols.useing the software called matalab to simulate the Performance of Data Link Control Protocols.二．实验原理 流量控制实际上是对发送方数据流量的控制，使其发送率不致超过接收方所能承受的能力。这个过程需要通过某种反馈机制使发送方知道接收方是否能跟上发送方，也即需要有一些规则使得发送方知道在什么情况下可以接着发送下一帧，而在什么情况下必须暂停发送，以等待收到某种反馈信息后继续发送。实验内容与要求Using the same assumptions that are used for Figure 7.13 in Appendix 7A, plot line utilization as a function of P, the probability that a single frame is in error for the following error-control techniques: a. Stop-and-wait b. Go-back-N with w=7 c. Go-back-N with w=127 d. Selective reject with w=7 e. Selective reject with w=127 Do all of the preceding for the following values of a: 0.1, 1, 10, 100. Draw conclusions about which technique is appropriate for various ranges of a. 实验程序与结果Project(1)a=0:0.1:1000;U=utilization(a,1); //when length of window is 1semilogx(a,U,b); //using function to depict linehold onU=utilization(a,7); //when length of window is 7semilogx(a,U,k);hold onU=utilization(a,127); //when length of window is 127semilogx(a,U,m);title(figure 7.12 slind-wind utilization as a function of a)ylabel(utilization)xlabel(a)text(0.7,0.5,\leftarrow w=1); //noting arrow to show what the line istext(8,0.6,\leftarrow w=7);text(130,0.8,\leftarrow w=127);function U=utilization(a,w) U=1.*(w=2*a+1)+w./(2*a+1).*(w2*a+1);End //formula for utilization U=1/(1+2a)Project(2)a=0:0.1:1000;p=1/1000;U=stopandwait(a,p); //using the formula to calculate the Usemilogx(a,U,r); //using function to depict linehold onU=selective_reject(a,7,p); //using the formula to calculate the Usemilogx(a,U,g);hold onU=gobackn(a,7,p);semilogx(a,U,b);hold onU=selective_reject(a,127,p);semilogx(a,U,k);hold onU=gobackn(a,1277,p);semilogx(a,U,y);title(figure 7.13 ARQ utilization as a function of a (P=10-3))ylabel(utilization)xlabel(a