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Recent Advances in TCP Congestion Control
Seungwan Ryu,Sung Hee Kim 에스케이텔레콤 (주) 2003 Telecommunications Review Vol.13 No.5
In this article, we first review the concept of congestion control with a focus on the Transmission Control Protocol/Internet Protocol (TCP/IP). We describe many recently proposed algorithms to combat congestion and improve performance, particularly active queue management (AQM) algorithms such as random early detection (RED) and its variants. We then survey control-theoretic analysis and design of TCP congestion control with an AQM scheme. In addition, we discuss three problems associated with AQM proposals: 1) parameter setting, 2) the insensitivity to the input traffic load variation, and 3) the mismatch between macroscopic and microscopic behavior of queue length dynamics. Then, we suggest requirements for an AQM algorithm to be adaptive to the various network situations. As alternatives to AQM algorithms, we also survey architectural approaches such as modification of source or network algorithms, and economic approaches including pricing or optimization of allocated resources. Finally, we list many open issues that persist in the design, operation and control of the Internet.
Ryu, Seungwan,Rump, Christopher M. The Korea Institute of Information and Commucation 2004 Journal of communications and networks Vol.6 No.2
Recently, many active queue management (AQM) algorithms have been proposed to address the performance degradation. of end-to-end congestion control under tail-drop (TD) queue management at Internet routers. However, these AQM algorithms show performance improvement only for limited network environments, and are insensitive to dynamically changing network situations. In this paper, we propose an adaptive queue management algorithm, called PID-controller, that uses proportional-integral-derivative (PID) feedback control to remedy these weak-Dalles of existing AQM proposals. The PID-controller is able to detect and control congestion adaptively and proactively to dynamically changing network environments using incipient as well as current congestion indications. A simulation study over a wide range of IP traffic conditions shows that PID-controller outperforms other AQM algorithms such as Random Early Detection (RED) [3] and Proportional-Integral (PI) controller [9] in terms of queue length dynamics, packet loss rates, and link utilization.
Seungwan Ryu,Sungsoon Yim,Seokmin Wi,Seungyun Jung,Sanghoon Kim,Byeonghee Kim 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
Among numerous process conditions, e.g. pressure, temperature, and RF, the pressure is one of the essential control parameters to influence on semiconductor manufacturing because its change affects the etch rate, selectivity, aspect ratio, and so on. Therefore, it is important to delicately and consistently control several reference pressures in process recipe. In this paper, we model a system of a process chamber as a transfer function using a time-domain system identification method. After then, a scheduled proportional-integral-differential (PID) controller is designed to regulate a series of reference pressure. To this end, we employ gain sets optimized by Genetic Algorithm (GA) considering control performance indices, i.e. overshoot, rise time, and settling time. Through our experimental results, we confirm that our control scheme shows appreciable improvement compared with a current pressure controller applied in mass production line.