Abstract: Active Queue Management（AQM） is very significant for network congestion control. This paper presents a new PID controller for AQM with ECN marks to overcome the shortcomings of PID AQM——high loss rate. In this algorithm, the mechanism of dropping packet is replaced with ECN marks. It uses the PID controller as feed-backward compensation to ensure the stability of the system. The results of simulation show that the PID controller for AQM with ECN marks can adapt to the changing network environment and has lower loss rate, lower delay and higher throughput than the conventional PID AQM algorithm.

Key words: congestion control, Active Queue Management（AQM）, Explicit Congestion Notification（ECN）, Proportion Integration Differentiation with Explicit Congestion Notification（ECNPID）

摘要： 主动队列管理对于解决网路拥塞具有重要意义。针对PID主动队列管理算法在调节队列长度时有较大的丢包率这一缺点，提出一种显示拥塞指示标记即ECN标记的PID主动队列管理算法。该算法用显示拥塞指示标记取代丢包机制，用于通知源端网络即将发生拥塞，采用PID控制器实现反馈控制，保证系统的稳定性。仿真结果表明，显示拥塞指示标记的主动队列管理算法适用于多变的网络环境，比PID算法具有低丢包率、低延时和高吞吐量的特点。

关键词: 拥塞控制, 主动队列管理, 显示拥塞指示（ECN）, 基于比例积分微分的显示拥塞指示记（ECNPID）