0 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，发包大小为512bytes；[3]给[4]发，发包间隔为，发包大小为512bytes。

二、实验结果：Node: 1, Layer: AppCbrClient, (0) Server address: 2Node: 1, Layer: AppCbrClient, (0) First packet sent at [s]:Node: 1, Layer: AppCbrClient, (0) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (0) Session status: Not closedNode: 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: 2, Layer: AppCbrServer, (0) Client address: 1Node: 2, Layer: AppCbrServer, (0) First packet received at [s]:Node: 2, Layer: AppCbrServer, (0) Last packet received at [s]:Node: 2, Layer: AppCbrServer, (0) Average end-to-end delay [s]:Node: 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: AppCbrServer, (0) Throughput (bits per second): 398078Node: 3, Layer: AppCbrClient, (0) Server address: 4Node: 3, Layer: AppCbrClient, (0) First packet sent at [s]:Node: 3, Layer: AppCbrClient, (0) Last packet sent at [s]:Node: 3, Layer: AppCbrClient, (0) Session status: Not closedNode: 3, Layer: AppCbrClient, (0) Total number of bytes sent: 5120000 Node: 3, Layer: AppCbrClient, (0) Total number of packets sent: 10000 Node: 3, Layer: AppCbrClient, (0) Throughput (bits per second): 409600 Node: 4, Layer: AppCbrServer, (0) Client address: 3Node: 4, Layer: AppCbrServer, (0) First packet received at [s]:Node: 4, Layer: AppCbrServer, (0) Last packet received at [s]:Node: 4, Layer: AppCbrServer, (0) Average end-to-end delay [s]:Node: 4, Layer: AppCbrServer, (0) Session status: Not closedNode: 4, Layer: AppCbrServer, (0) Total number of bytes received: 5120000 Node: 4, Layer: AppCbrServer, (0) Total number of packets received: 10000 Node: 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，发包大小为512bytes；[3]给[4]发，发包间隔为，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：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，分别测出5、 10、 15 、20 、 25 、 30 、 35 、 40 、 45 、 50 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]:Node: 1, Layer: AppCbrClient, (4) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (4) Session status: Not closedNode: 1, Layer: AppCbrClient, (4) Total number of bytes sent: 5120000 Node: 1, Layer: AppCbrClient, (4) Total number of packets sent: 10000 Node: 1, Layer: AppCbrClient, (4) Throughput (bits per second): 409600 Node: 1, Layer: AppCbrClient, (3) Server address: 54Node: 1, Layer: AppCbrClient, (3) First packet sent at [s]:Node: 1, Layer: AppCbrClient, (3) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (3) Session status: Not closedNode: 1, Layer: AppCbrClient, (3) Total number of bytes sent: 5120000 Node: 1, Layer: AppCbrClient, (3) Total number of packets sent: 10000Node: 1, Layer: AppCbrClient, (3) Throughput (bits per second): 409600 Node: 1, Layer: AppCbrClient, (2) Server address: 53Node: 1, Layer: AppCbrClient, (2) First packet sent at [s]:Node: 1, Layer: AppCbrClient, (2) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (2) Session status: Not closedNode: 1, Layer: AppCbrClient, (2) Total number of bytes sent: 5120000 Node: 1, Layer: AppCbrClient, (2) Total number of packets sent: 10000 Node: 1, Layer: AppCbrClient, (2) Throughput (bits per second): 409600 Node: 1, Layer: AppCbrClient, (1) Server address: 52Node: 1, Layer: AppCbrClient, (1) First packet sent at [s]:Node: 1, Layer: AppCbrClient, (1) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (1) Session status: Not closedNode: 1, Layer: AppCbrClient, (1) Total number of bytes sent: 5120000 Node: 1, Layer: AppCbrClient, (1) Total number of packets sent: 10000 Node: 1, Layer: AppCbrClient, (1) Throughput (bits per second): 409600 Node: 1, Layer: AppCbrClient, (0) Server address: 51Node: 1, Layer: AppCbrClient, (0) First packet sent at [s]:Node: 1, Layer: AppCbrClient, (0) Last packet sent at [s]:Node: 1, Layer: AppCbrClient, (0) Session status: Not closedNode: 1, Layer: AppCbrClient, (0) Total number of bytes sent: 5120000 Node: 1, Layer: AppCbrClient, (0) Total number of packets sent: 10000 Node: 1, Layer: AppCbrClient, (0) Throughput (bits per second): 409600 Node: 51, Layer: AppCbrServer, (0) Client address: 1Node: 51, Layer: AppCbrServer, (0) First packet received at [s]: Node: 51, Layer: AppCbrServer, (0) Last packet received at [s]:Node: 51, Layer: AppCbrServer, (0) Average end-to-end delay [s]: Node: 51, Layer: AppCbrServer, (0) Session status: Not closedNode: 51, Layer: AppCbrServer, (0) Total number of bytes received: 5102592 Node: 51, Layer: AppCbrServer, (0) Total number of packets received: 9966 Node: 51, Layer: AppCbrServer, (0) Throughput (bits per second): 408219 Node: 52, Layer: AppCbrServer, (1) Client address: 1Node: 52, Layer: AppCbrServer, (1) First packet received at [s]: Node: 52, Layer: AppCbrServer, (1) Last packet received at [s]:Node: 52, Layer: AppCbrServer, (1) Average end-to-end delay [s]: Node: 52, Layer: AppCbrServer, (1) Session status: Not closedNode: 52, Layer: AppCbrServer, (1) Total number of bytes received: 5102592 Node: 52, Layer: AppCbrServer, (1) Total number of packets received: 9966 Node: 52, Layer: AppCbrServer, (1) Throughput (bits per second): 408233 Node: 53, Layer: AppCbrServer, (2) Client address: 1Node: 53, Layer: AppCbrServer, (2) First packet received at [s]: Node: 53, Layer: AppCbrServer, (2) Last packet received at [s]:Node: 53, Layer: AppCbrServer, (2) Average end-to-end delay [s]: Node: 53, Layer: AppCbrServer, (2) Session status: Not closedNode: 53, Layer: AppCbrServer, (2) Total number of bytes received: 3926016 Node: 53, Layer: AppCbrServer, (2) Total number of packets received: 7668 Node: 53, Layer: AppCbrServer, (2) Throughput (bits per second): 314112 Node: 54, Layer: AppCbrServer, (3) Client address: 1Node: 54, Layer: AppCbrServer, (3) First packet received at [s]: Node: 54, Layer: AppCbrServer, (3) Last packet received at [s]:Node: 54, Layer: AppCbrServer, (3) Average end-to-end delay [s]:Node: 54, Layer: AppCbrServer, (3) Session status: Not closedNode: 54, Layer: AppCbrServer, (3) Total number of bytes received: 22016 Node: 54, Layer: AppCbrServer, (3) Total number of packets received: 43 Node: 54, Layer: AppCbrServer, (3) Throughput (bits per second): 1761 Node: 55, Layer: AppCbrServer, (4) Client address: 1Node: 55, Layer: AppCbrServer, (4) First packet received at [s]: Node: 55, Layer: AppCbrServer, (4) Last packet received at [s]:Node: 55, Layer: AppCbrServer, (4) Average end-to-end delay [s]: Node: 55, Layer: AppCbrServer, (4) Session status: Not closedNode: 55, Layer: AppCbrServer, (4) Total number of bytes received: 22016 Node: 55, Layer: AppCbrServer, (4) Total number of packets received: 43 Node: 55, Layer: AppCbrServer, (4) Throughput (bits per second): 1761 10、15、20、25、30、35、40、45、50条省略各发送节点发包间隔较大，当网络中发送节点较少时，网络还未饱和。