APID:一种自适应调节参数的拥塞控制器

摘要

Considering the network dynamics, the congestion controllers designed according to the linear control theory may aggravate the oscillation of buffer occupancy and cause the degradation of bandwidth utilization, to solve the problem, the transfer function of TCP/AQM control process was studied, the relationship between buffer occupancy and packet drop probability was analyzed, and then the proper parameters of PID were calculated using the buffer occupancy and packet drop probability measured in the router. A congestion controller called APID which can tuning parameters adaptively according to the network dynamic was proposed. The simulation results show that the APID can tune the parameters of PID controller adaptively, and consequently achieves strong stability in buffer occupancy and high link utilization. It outperforms the PI, REM, IMC-PID, LRED and AOPC in terms of buffer stability and link utilization in different end-to-end delay scenarios.%在网络状态发生变化的情况下,现有的根据传统线性控制理论设计的拥塞控制器导致路由器缓冲队列抖动加剧、网络带宽利用率下降,针对此问题,分析TCP/AQM拥塞控制机制中受控过程的传递函数,得到受控过程队列长度和丢包概率之间的关系,利用此关系式并结合路由器上实际测量到的队列长度和丢包概率,计算出符合当前网络状态的PID控制器参数,提出一种自适应调节参数的PID拥塞控制器APID.仿真实验结果表明:APID算法能够动态地调节PID控制器的参数,比PI,REM,IMC-PID,LRED和AOPC等算法具有更好的队列稳定性和更高的带宽利用率.