利用所学数据链路层原理，自己设计一个滑动窗口协议，在仿真环境下编程实现有噪音信道环境下两站点之间无差错双工通信。信道模型为8000bps全双工卫星信道，信道传播时延270毫秒，信道误码率为10-5，信道提供字节流传输服务，网络层分组长度固定为256字节。

通过该实验，进一步巩固和深刻理解数据链路层误码检测的CRC校验技术，以及滑动窗口的工作机理。滑动窗口机制的两个主要目标：(1) 实现有噪音信道环境下的无差错传输 (2)充分利用传输信道的带宽。在程序能够稳定运行并成功实现第一个目标之后，运行程序并检查在信道没有误码和存在误码两种情况下的信道利用率。为实现第二个目标，提高滑动窗口协议信道利用率，需要根据信道实际情况合理地为协议配置工作参数，包括滑动窗口的大小和重传定时器时限以及ACK搭载定时器的时限。这些参数的设计，需要充分理解滑动窗口协议的工作原理并利用所学的理论知识，经过认真的推算，计算出最优取值，并通过程序的运行进行验证。-To use the data link layer principle of their own design of a sliding window protocol programming error-free duplex communication between two sites of the noise channel environment in the simulation environment. 8000bps full-duplex channel model satellite channel, the channel propagation delay of 270 milliseconds, the channel bit error rate of 10-5, the channel byte streaming services, network layer packet length is fixed at 256 bytes.

Further consolidated through the experiment, and a deep understanding of the CRC checksum of the data link layer error detection technology, as well as the working mechanism of the sliding window. Sliding window mechanism two main objectives: (1) to achieve error-free transmission of the noise channel environment　(2) make full use of the bandwidth of the transmission channel. Running the program in the program can be stably and successfully achieve the first objective, and checks the utilization of a channel in the case of no code error and the error e