计算机与通信网络实验报告

1、计算机与通信网络实验报告041220111 戴妍实验一隐终端和暴露终端问题分析一、实验设定：基本参数配置：仿真时长100s；随机数种子1；仿真区域2000x2000；节点数4。节点位置配置：本实验用1、2、3、4共两对节点验证隐终端问题。节点1、2距离为200m，节点3、4距离为200m，节点2、3距离为370m。业务流配置：业务类型为恒定比特流CBR。1给2发，发包间隔为0.01s，发包大小为512bytes；3给4发，发包间隔为0.01s，发包大小为512bytes。二、实验结果：Node: 1, Layer: AppCbrClient, (0) Server address: 2Node

2、: 1, Layer: AppCbrClient, (0) First packet sent at s: 0.000000000Node: 1, Layer: AppCbrClient, (0) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (0) Session status: Not closedNode: 1, Layer: AppCbrClient, (0) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (0) Tot

3、al number of packets sent: 10000Node: 1, Layer: AppCbrClient, (0) Throughput (bits per second): 409600Node: 2, Layer: AppCbrServer, (0) Client address: 1Node: 2, Layer: AppCbrServer, (0) First packet received at s: 0.007438001Node: 2, Layer: AppCbrServer, (0) Last packet received at s: 99.999922073N

4、ode: 2, Layer: AppCbrServer, (0) Average end-to-end delay s: 0.739902205Node: 2, Layer: AppCbrServer, (0) Session status: Not closedNode: 2, Layer: AppCbrServer, (0) Total number of bytes received: 4975616Node: 2, Layer: AppCbrServer, (0) Total number of packets received: 9718Node: 2, Layer: AppCbrS

5、erver, (0) Throughput (bits per second): 398078Node: 3, Layer: AppCbrClient, (0) Server address: 4Node: 3, Layer: AppCbrClient, (0) First packet sent at s: 0.000000000Node: 3, Layer: AppCbrClient, (0) Last packet sent at s: 99.990000000Node: 3, Layer: AppCbrClient, (0) Session status: Not closedNode

6、: 3, Layer: AppCbrClient, (0) Total number of bytes sent: 5120000Node: 3, Layer: AppCbrClient, (0) Total number of packets sent: 10000Node: 3, Layer: AppCbrClient, (0) Throughput (bits per second): 409600Node: 4, Layer: AppCbrServer, (0) Client address: 3Node: 4, Layer: AppCbrServer, (0) First packe

7、t received at s: 0.003058001Node: 4, Layer: AppCbrServer, (0) Last packet received at s: 99.993058001Node: 4, Layer: AppCbrServer, (0) Average end-to-end delay s: 0.003119031Node: 4, Layer: AppCbrServer, (0) Session status: Not closedNode: 4, Layer: AppCbrServer, (0) Total number of bytes received:

8、5120000Node: 4, Layer: AppCbrServer, (0) Total number of packets received: 10000Node: 4, Layer: AppCbrServer, (0) Throughput (bits per second): 409612 通过仿真结果可以看出，节点2无法收到数据。由于节点3是节点1的一个隐终端，节点1无法通过物理载波检测侦听到节点3的发送，且节点3在节点2的传输范围外，节点3无法通过虚拟载波检测延迟发送，所以在节点1传输数据的过程中，节点3完成退避发送时将引起冲突。三、课后思考1、RTS/CTS能完全解决隐终端问题

9、吗？如果不能，请说明理由。答：能。对于隐发送终端问题，2和3使用控制报文进行握手（RTS-CTS），听到回应握手信号的3知道自己是隐终端，便能延迟发送；对于隐接受终端问题，在多信道的情况下，3给4回送CTS告诉4它是隐终端，现在不能发送报文，以避免4收不到3的应答而超时重发浪费带宽。2、如何设计仿真场景来验证暴露终端问题？答：只需更改业务流配置：业务类型为恒定比特流CBR。2给1发，发包间隔为0.01s，发包大小为512bytes；3给4发，发包间隔为0.01s，发包大小为512bytes。观察在2给1发送数据的同时，3给4发送数据会不会被影响。3、如何设计协议使暴露终端场景下的流实现并发？答

10、：至少要使用两个信道资源，在数据信道上进行RTS-CTS握手，在数据信道上发送数据报文。在2给1发送数据报文时，3也想向4发送数据报文，通过控制信道向4发送RTS，4也从控制信道向3回送CTS，这样3就不会因为2的数据信号和4的回应信号产生碰撞而听不到4的回应了。这样就可以实现并发了。实验二 无线局域网DCF协议饱和吞吐量验证1、 实验设定基本参数配置：仿真时长100S随机数种子1仿真区域150x150节点数100。业务流配置：业务类型为CBR，发包大小为512bytes，发包间隔为0.01S，分别测出5、 10、 15 、 20 、 25 、 30 、 35 、 40 、 45 、 50 条

11、流的吞吐量。二、实验结果：5条：Node: 1, Layer: AppCbrClient, (4) Server address: 55Node: 1, Layer: AppCbrClient, (4) First packet sent at s: 0.000000000Node: 1, Layer: AppCbrClient, (4) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (4) Session status: Not closedNode: 1, Layer: AppCbrClient, (4)

12、Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (4) Total number of packets sent: 10000Node: 1, Layer: AppCbrClient, (4) Throughput (bits per second): 409600Node: 1, Layer: AppCbrClient, (3) Server address: 54Node: 1, Layer: AppCbrClient, (3) First packet sent at s: 0.000000000Node:

13、 1, Layer: AppCbrClient, (3) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (3) Session status: Not closedNode: 1, Layer: AppCbrClient, (3) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (3) Total number of packets sent: 10000Node: 1, Layer: AppCbrClient, (3) Thro

14、ughput (bits per second): 409600Node: 1, Layer: AppCbrClient, (2) Server address: 53Node: 1, Layer: AppCbrClient, (2) First packet sent at s: 0.000000000Node: 1, Layer: AppCbrClient, (2) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (2) Session status: Not closedNode: 1, Layer: Ap

15、pCbrClient, (2) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (2) Total number of packets sent: 10000Node: 1, Layer: AppCbrClient, (2) Throughput (bits per second): 409600Node: 1, Layer: AppCbrClient, (1) Server address: 52Node: 1, Layer: AppCbrClient, (1) First packet sent at s:

16、0.000000000Node: 1, Layer: AppCbrClient, (1) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (1) Session status: Not closedNode: 1, Layer: AppCbrClient, (1) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (1) Total number of packets sent: 10000Node: 1, Layer: AppCbr

17、Client, (1) Throughput (bits per second): 409600Node: 1, Layer: AppCbrClient, (0) Server address: 51Node: 1, Layer: AppCbrClient, (0) First packet sent at s: 0.000000000Node: 1, Layer: AppCbrClient, (0) Last packet sent at s: 99.990000000Node: 1, Layer: AppCbrClient, (0) Session status: Not closedNo

18、de: 1, Layer: AppCbrClient, (0) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClient, (0) Total number of packets sent: 10000Node: 1, Layer: AppCbrClient, (0) Throughput (bits per second): 409600Node: 51, Layer: AppCbrServer, (0) Client address: 1Node: 51, Layer: AppCbrServer, (0) First p

19、acket received at s: 0.003056858Node: 51, Layer: AppCbrServer, (0) Last packet received at s: 99.995493030Node: 51, Layer: AppCbrServer, (0) Average end-to-end delay s: 0.351972641Node: 51, Layer: AppCbrServer, (0) Session status: Not closedNode: 51, Layer: AppCbrServer, (0) Total number of bytes re

20、ceived: 5102592Node: 51, Layer: AppCbrServer, (0) Total number of packets received: 9966Node: 51, Layer: AppCbrServer, (0) Throughput (bits per second): 408219Node: 52, Layer: AppCbrServer, (1) Client address: 1Node: 52, Layer: AppCbrServer, (1) First packet received at s: 0.006449537Node: 52, Layer

21、: AppCbrServer, (1) Last packet received at s: 99.998965709Node: 52, Layer: AppCbrServer, (1) Average end-to-end delay s: 0.355584451Node: 52, Layer: AppCbrServer, (1) Session status: Not closedNode: 52, Layer: AppCbrServer, (1) Total number of bytes received: 5102592Node: 52, Layer: AppCbrServer, (

22、1) Total number of packets received: 9966Node: 52, Layer: AppCbrServer, (1) Throughput (bits per second): 408233Node: 53, Layer: AppCbrServer, (2) Client address: 1Node: 53, Layer: AppCbrServer, (2) First packet received at s: 0.010001809Node: 53, Layer: AppCbrServer, (2) Last packet received at s:

23、99.992000125Node: 53, Layer: AppCbrServer, (2) Average end-to-end delay s: 0.358534977Node: 53, Layer: AppCbrServer, (2) Session status: Not closedNode: 53, Layer: AppCbrServer, (2) Total number of bytes received: 3926016Node: 53, Layer: AppCbrServer, (2) Total number of packets received: 7668Node:

24、53, Layer: AppCbrServer, (2) Throughput (bits per second): 314112Node: 54, Layer: AppCbrServer, (3) Client address: 1Node: 54, Layer: AppCbrServer, (3) First packet received at s: 0.013774900Node: 54, Layer: AppCbrServer, (3) Last packet received at s: 0.773715844Node: 54, Layer: AppCbrServer, (3) A

25、verage end-to-end delay s: 0.184107930Node: 54, Layer: AppCbrServer, (3) Session status: Not closedNode: 54, Layer: AppCbrServer, (3) Total number of bytes received: 22016Node: 54, Layer: AppCbrServer, (3) Total number of packets received: 43Node: 54, Layer: AppCbrServer, (3) Throughput (bits per se

26、cond): 1761Node: 55, Layer: AppCbrServer, (4) Client address: 1Node: 55, Layer: AppCbrServer, (4) First packet received at s: 0.017127686Node: 55, Layer: AppCbrServer, (4) Last packet received at s: 0.777148630Node: 55, Layer: AppCbrServer, (4) Average end-to-end delay s: 0.187729553Node: 55, Layer:

27、 AppCbrServer, (4) Session status: Not closedNode: 55, Layer: AppCbrServer, (4) Total number of bytes received: 22016Node: 55, Layer: AppCbrServer, (4) Total number of packets received: 43Node: 55, Layer: AppCbrServer, (4) Throughput (bits per second): 176110、15、20、25、30、35、40、45、50条省略各发送节点发包间隔较大，当网

28、络中发送节点较少时，网络还未饱和。逐渐往网络中增加负载，网络总吞吐量逐渐增大，之后，网络吞吐量逐渐趋向于平稳，此时，网络即达到了饱和状态。三、课后思考1 、总结IEEE 802.11DCF协议饱和吞吐量和哪些因素有关。 任选一个时隙，网络中有节点在发送数据的概率当有节点在发送数据包时，数据包发送成功的概率数据包发送成功和发送失败所需的时间2 、为什么在数据包长度较长时，采用 RTS/CTS 模式更合理？ 隐藏终端多发生在大型单元中（一般在室外环境），这将带来效率损失，并且需要错误恢复机制。当需要传送大容量文件时，尤其需要杜绝隐藏终端现象的发生。3 、本实验中提出的马尔科夫链模型只适用于单跳模型

29、，若应用到多跳网络中时，需如何改进？于定长时隙的多跳ad hoc网络DCF协议马尔可夫链模型实验三动态源路由协议路由选择验证一、实验设定基本参数配置：仿真时长100S；随机数种子1；仿真区域2000x2000；节点数5。节点位置配置：用节点1-5来验证DSR路由协议的路由发现过程。1和2、2和3、3和4、3和5、4和6、5和6之间距离为200m。设置业务流：1给2发，发包间隔0.01s，发包大小512Bytes。设置节点移动性：节点1为移动节点，仿真过程中绕网格拓扑转一圈。二、实验结果：Time(s): 1.000001000, Node: 1, Route path: 2Time(s): 2

30、.000001000, Node: 1, Route path: 2Time(s): 3.000001000, Node: 1, Route path: 2Time(s): 4.000001000, Node: 1, Route path: 2Time(s): 5.000001000, Node: 1, Route path: 2Time(s): 6.000001000, Node: 1, Route path: 2Time(s): 7.000001000, Node: 1, Route path: 2Time(s): 8.000001000, Node: 1, Route path: 4-2

31、Time(s): 9.000001000, Node: 1, Route path: 4-2Time(s): 10.000001000, Node: 1, Route path: 4-2Time(s): 11.000001000, Node: 1, Route path: 4-2Time(s): 12.000001000, Node: 1, Route path: 4-2Time(s): 13.000001000, Node: 1, Route path: 4-2Time(s): 14.000001000, Node: 1, Route path: 4-2Time(s): 15.0000010

32、00, Node: 1, Route path: 4-2Time(s): 16.000001000, Node: 1, Route path: 4-2Time(s): 17.000001000, Node: 1, Route path: 4-2Time(s): 18.000001000, Node: 1, Route path: 4-2Time(s): 19.000001000, Node: 1, Route path: 4-2Time(s): 20.000001000, Node: 1, Route path: 4-2Time(s): 21.000001000, Node: 1, Route

33、 path: 4-2Time(s): 22.000001000, Node: 1, Route path: 4-2Time(s): 23.000001000, Node: 1, Route path: 4-2Time(s): 24.000001000, Node: 1, Route path: 4-2Time(s): 25.000001000, Node: 1, Route path: 4-2Time(s): 26.000001000, Node: 1, Route path: 4-2Time(s): 27.000001000, Node: 1, Route path: 4-2Time(s):

34、 28.000001000, Node: 1, Route path: 4-2Time(s): 29.000001000, Node: 1, Route path: 4-2Time(s): 30.000001000, Node: 1, Route path: 4-2Time(s): 31.000001000, Node: 1, Route path: 4-2Time(s): 32.000001000, Node: 1, Route path: 4-2Time(s): 33.000001000, Node: 1, Route path: 4-2Time(s): 34.000001000, Nod

35、e: 1, Route path: 4-2Time(s): 35.000001000, Node: 1, Route path: 4-2Time(s): 36.000001000, Node: 1, Route path: 4-2Time(s): 37.000001000, Node: 1, Route path: 4-2Time(s): 38.000001000, Node: 1, Route path: 5-4-2Time(s): 39.000001000, Node: 1, Route path: 5-4-2Time(s): 40.000001000, Node: 1, Route pa

36、th: 5-4-2Time(s): 41.000001000, Node: 1, Route path: 5-4-2Time(s): 42.000001000, Node: 1, Route path: 5-4-2Time(s): 43.000001000, Node: 1, Route path: 5-4-2Time(s): 44.000001000, Node: 1, Route path: 5-4-2Time(s): 45.000001000, Node: 1, Route path: 5-4-2Time(s): 46.000001000, Node: 1, Route path: 5-

37、4-2Time(s): 47.000001000, Node: 1, Route path: 5-4-2Time(s): 48.000001000, Node: 1, Route path: 5-4-2Time(s): 49.000001000, Node: 1, Route path: 5-4-2Time(s): 50.000001000, Node: 1, Route path: 5-4-2Time(s): 51.000001000, Node: 1, Route path: 5-4-2Time(s): 52.000001000, Node: 1, Route path: 5-4-2Tim

38、e(s): 53.000001000, Node: 1, Route path: 5-4-2Time(s): 54.000001000, Node: 1, Route path: 5-4-2Time(s): 55.000001000, Node: 1, Route path: 5-4-2Time(s): 56.000001000, Node: 1, Route path: 5-4-2Time(s): 57.000001000, Node: 1, Route path: 5-4-2Time(s): 58.000001000, Node: 1, Route path: 5-4-2Time(s):

39、59.000001000, Node: 1, Route path: 5-4-2Time(s): 60.000001000, Node: 1, Route path: 5-4-2Time(s): 61.000001000, Node: 1, Route path: 5-4-2Time(s): 62.000001000, Node: 1, Route path: 5-4-2Time(s): 63.000001000, Node: 1, Route path: 5-4-2Time(s): 64.000001000, Node: 1, Route path: 5-4-2Time(s): 65.000

40、001000, Node: 1, Route path: 5-4-2Time(s): 66.000001000, Node: 1, Route path: 5-4-2Time(s): 67.000001000, Node: 1, Route path: 5-4-2Time(s): 68.000001000, Node: 1, Route path: 3-2Time(s): 69.000001000, Node: 1, Route path: 3-2Time(s): 70.000001000, Node: 1, Route path: 3-2Time(s): 71.000001000, Node

41、: 1, Route path: 3-2Time(s): 72.000001000, Node: 1, Route path: 3-2Time(s): 73.000001000, Node: 1, Route path: 3-2Time(s): 74.000001000, Node: 1, Route path: 3-2Time(s): 75.000001000, Node: 1, Route path: 3-2Time(s): 76.000001000, Node: 1, Route path: 3-2Time(s): 77.000001000, Node: 1, Route path: 3

42、-2Time(s): 78.000001000, Node: 1, Route path: 3-2Time(s): 79.000001000, Node: 1, Route path: 3-2Time(s): 80.000001000, Node: 1, Route path: 3-2Time(s): 81.000001000, Node: 1, Route path: 3-2Time(s): 82.000001000, Node: 1, Route path: 3-2Time(s): 83.000001000, Node: 1, Route path: 3-2Time(s): 84.0000

43、01000, Node: 1, Route path: 3-2Time(s): 85.000001000, Node: 1, Route path: 3-2Time(s): 86.000001000, Node: 1, Route path: 3-2Time(s): 87.000001000, Node: 1, Route path: 3-2Time(s): 88.000001000, Node: 1, Route path: 3-2Time(s): 89.000001000, Node: 1, Route path: 3-2Time(s): 90.000001000, Node: 1, Route path: 3-2Time(s): 91.000001000, Node: 1, Route path: 3-2Time(s): 92.000001000, Node: 1, Route path: 3-2Time(s): 93.00