基于前向纠错的自适应网络传输机制

针对无线网络中的传输控制协议（TCP）因为丢包触发丢包重传机制而导致传输性能大幅下降的问题，提出了一种基于前向纠错的自适应传输机制（AdaptiveFEC）。该机制通过前向纠错来减少数据段的丢失，以避免触发TCP的丢包重传机制，从而达到提升TCP传输性能的目的。首先，根据当前的网络状况以及当前连接的数据传输特征确定当前时间段中的最优冗余段比例；然后，利用TCP数据段中的数据段序号信息实时进行网络状况的估计，从而根据网络波动来动态更新冗余段比例。大量实验结果说明，在20 ms的往返时延以及5%丢包率的传输环境中，相较于静态的前向纠错机制，AdaptiveFEC能够使得TCP连接的传输速率平均提升42%，当运用在文件下载的应用中时，所提机制能够使得下载速度提升至原来的两倍。

Adaptive network transmission mechanism based on forward error correction

Aiming at the performance degradation of transmission performance of Transmission Control Protocol (TCP) in wireless network caused by the loss packet retransmission mechanism triggered by packet loss, an Adaptive transmission mechanism based on Forward Error Correction (AdaptiveFEC) was proposed. In the mechanism, the transmission performance of TCP was improved by the avoidance of triggering TCP loss packet retransmission mechanism, which realized by reducing data segment loss with forward error correction. Firstly, the optimal redundant segment ratio in current time was selected according to the current network status and the data transmission characteristics of the current connection. Then, the network status was estimated by analyzing the data segment sequence number in the TCP data segment, so that the redundant segment ratio was dynamically updated according to the network. Large number of experiment results show that, in the transmission environment with a round-trip delay of 20 ms and a packet loss rate of 5%, AdaptiveFEC can increase the transmission rate of TCP connection by 42% averagely compared to static forward error correction mechanism, and the download speed can be twice as much as the original speed with the proposed mechanism applied to file download applications.