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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): 398078 / Node: 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 closedN
6、ode: 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 pa
7、cket 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 receive
8、d: 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
9、端问题吗？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
10、发？答：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 、 5
11、0 条流的吞吐量。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, (
12、4) 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: 0.000000000No
13、de: 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) T
14、hroughput (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: AppCbrClient, (2) Total number of bytes sent: 5120000Node: 1, Layer: AppCbrClien
