• Title, Summary, Keyword: Congestion Management

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Stochastic Traffic Congestion Evaluation of Korean Highway Traffic Information System with Structural Changes

  • Lee, Yongwoong;Jeon, Saebom;Park, Yousung
    • Asia pacific journal of information systems
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    • v.26 no.3
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    • pp.427-448
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    • 2016
  • The stochastic phenomena of traffic network condition, such as traffic speed and density, are affected not only by exogenous traffic control but also by endogenous changes in service time during congestion. In this paper, we propose a mixed M/G/1 queuing model by introducing a condition-varying parameter of traffic congestion to reflect structural changes in the traffic network. We also develop congestion indices to evaluate network efficiency in terms of traffic flow and economic cost in traffic operating system using structure-changing queuing model, and perform scenario analysis according to various traffic network improvement policies. Empirical analysis using Korean highway traffic operating system shows that our suggested model better captures structural changes in the traffic queue. The scenario analysis also shows that occasional reversible lane operation during peak times can be more efficient and feasible than regular lane extension in Korea.

Double Queue CBOKe Mechanism for Congestion Control (이중 큐 CHOKe 방식을 사용한 혼잡제어)

  • 최기현;신호진;신동렬
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.11A
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    • pp.867-875
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    • 2003
  • Current end-to-end congestion control depends only on the information of end points (using three duplicate ACK packets) and generally responds slowly to the network congestion. This mechanism can't avoid TCP global synchronization in which TCP congestion window size is fluctuated during congestion period. Furthermore, if RTT(Round Trip Time) is increased, three duplicate ACK packets are not correct congestion signals because congestion might already disappear and the host may send more packets until it receives three duplicate ACK packets. Recently there are increasing interests in solving end-to-end congestion control using AQM(Active Queue Management) to improve the performance of TCP protocols. AQM is a variation of RED-based congestion control. In this paper, we first evaluate the effectiveness of the current AQM schemes such as RED, CHOKe, ARED, FRED and SRED, over traffic with different rates and over traffic with mixed responsive and non-responsive flows, respectively. In particular, CHOKe mechanism shows greater unfairness, especially when more unresponsive flows exist in a shared link. We then propose a new AQM scheme using CHOKe mechanism, called DQC(Double Queue CHOKe), which uses two FIFO queues before applying CHOKe mechanism to adaptive congestion control. Simulation shows that it works well in protecting congestion-sensitive flows from congestion-causing flows and exhibits better performances than other AQM schemes. Also we use partial state information, proposed in LRURED, to improve our mechanism.

An Effective RED Algorithm for Congestion Control in the Internet (인터넷에서 혼잡제어를 위한 개선된 RED 알고리즘)

  • Jung, Kyu-Jung;Lee, Dong-Ho
    • The KIPS Transactions:PartC
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    • v.10C no.1
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    • pp.39-44
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    • 2003
  • The network performance gets down during congestion periods to solve the problem effectively. A RED(Random Earl Detection) algorithm of the queue management algorithm is proposed and IETF recommends it as a queue management. A RED algorithm controls a congestion aspect dynamically. In analyzing parameters when static value of parameter is set in the gateway cannot be handled the status of current network traffic properly We propose the Effective RED algorithm to solve with the weakness of RED In this algorithm the maximum drop probability decides to accept or drop the interning packets, is adjusted dynamically on the current queue state for controlling the congestion phase effectively in the gateway. This algorithm is confirmed by computer simulation using the NS(Network Simulator)-2.

Enhanced ERICA Switch Algorithm using Buffer Management Scheme (버퍼 관리 기법을 이용한 개선된 ERICA 스위치 알고리즘)

  • 양기원;오창석
    • The Journal of the Korea Contents Association
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    • v.2 no.2
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    • pp.73-84
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    • 2002
  • In this paper, we propose a enhanced ERICA switch algorithm using the buffer management scheme which can reduce the queue length, support the efficiency link utilization and the fair share. It has three different buffer thresholds which are low threshold, congestion notification threshold and high threshold. According to the each buffer threshold status, switch announced congestion notification to the source differently. So, sources could know the congestion more quickly and fast remover from network congestion. As a experimental results, it is proved that proposed algorithm is the more efficient than ERICA. Especially, proposed switch algorithm provides congestion control mechanism to make the best use of with keeping fairness and reduce queue length.

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Maximizing the Overall Satisfaction Degree of all Participants in the Market Using Real Code-based Genetic Algorithm by Optimally Locating and Sizing the Thyristor-Controlled Series Capacitor

  • Nabavi, Seyed M.H.;Hajforoosh, Somayeh;Hajforoosh, Sajad;Karimi, Ali;Khafafi, Kamran
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.493-504
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    • 2011
  • The present paper presents a genetic algorithm (GA) to maximize social welfare and perform congestion management by optimally placing and sizing one Thyristor-Controlled Series Capacitor (TCSC) device in a double-sided auction market. Simulation results, with line flow constraints before and after the compensation, are compared through the Sequential Quadratic Programming SQP method, and are used to analyze the effect of TCSC on the congestion levels of modified IEEE 14-bus and 30-bus test systems. Quadratic, smooth and nonsmooth (with sine components due to valve point loading effect) generator cost curves, and quadratic smooth consumer benefit functions are considered. The main aims of the present study are the inclusion of customer benefit in the social welfare maximization and congestion management objective function, the consideration of nonsmooth generator characteristics, and the optimal locating and sizing of the TCSC using real code-based GA to guarantee fast convergence to the best solution.

A study on congesting control scheme for LAN interworkding in connectionless data service (비연결형 데이터 서비스에서 LAN연동을 위한 폭주 제어에 관한 연구)

  • 박천관;전병천;김영선
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.3
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    • pp.29-38
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    • 1998
  • This ppaer suggests a congestion control scheme for CL(ConnectionLess) overlay network using the feedback loops getween CL werver, between CL servers, and the header translation table of CL server. The CL overlay network for CBDS(Connectionless Broadband Data Service) defined by ITU0T(International Telecommunication Union-Telecommunication) consists of CL servers which route frames and links which connect between CL user and CL server or between CL servers. In this CL overlay network, two kinds of congestions, link congestion and CL server congestion, may occur. We suggest a scheme that can solve the congestion using ABR(Available Bit Rate) feedback control loop, the traffic control mechanism. This scheme is the link-by-link method suing the ABR feedback control loops between CL user and CL server or between CL servers, and the header translation table of CL server. As CL servers are always endpoints of ABR connections, the congestion staturs of the CL server can be informed to the traffic sources using RM(Resource Management) cell of the ABR feedback loops. Also CL server knows the trafffic sources making congestion by inspecting the source address field of CLNAP-PDUs(ConnectionLess Network Access Protocol - Protocol Data Units). Therefore this scheme can be implemeted easily using only both ABR feedback control loop of ATM layer and the congestion state table using the header translation table of CL server because it does not require separate feedback links for congestion control of CL servers.

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Development of a Traffic Condition Index (TCI) on Expressways (고속도로 소통상태지수 개발에 관한 연구)

  • Bok, Gi-Chan;Lee, Seung-Jun;Choe, Yun-Hyeok;Gang, Jeong-Gyu;Lee, Seung-Hwan
    • Journal of Korean Society of Transportation
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    • v.27 no.5
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    • pp.85-95
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    • 2009
  • Congestion on expressways is increasing in spite of continuous road construction. In enlargement of expressway capacity to lessen congestion, a long period is needed and in the case of traffic congestion, it would be impossible to avoid long periods of traffic congestion. So, it is necessary to cope with traffic congestion through continuous traffic condition monitoring, analysis of the causes of congestion and the development of alternatives before traffic conditions worsen. A congestion index that can express traffic operating conditions measurably is needed to monitor those conditions. Thus, in this research, a new congestion index, the Traffic Condition Index (TCI), is developed. TCI is able to evaluate roads that have different grades (or design speeds) and to judge traffic condition as good, fair and poor (congested). In addition, TCI has merits in that it can strengthen the function of existing Freeway Traffic Management Systems (FTMS) and can be applied to congestion management easily: TCI calculates congestion intensity and severity using data obtained from existing FTMS. In order to validate TCI, it was applied to the Kyungbu Expressway and the Seohaean Expressway. As a result, TCI shows a good performance in the aspect of applicability and ability of presentation of traffic conditions compared with travel speed and Travel Time Index (TTI).

A Study on the Feasibility of the Improvement of Traffic Congestion : Focusing on Small and Medium-Sized Cities in Chuncheong Province (중소도시 교통혼잡도로 적용범위에 관한 연구 : 충청권 중심으로)

  • Kwon, Hyun Joong;Oh, Ju Taek
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.18 no.3
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    • pp.34-45
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    • 2019
  • Based on the analysis of congestion conditions in small cities with a population of less than 500,000 in Chungcheong Province, this study conducted a feasibility study on the scope of congestion improvement projects. Further, traffic congestion management standards were further established by analyzing LOS as well as the speed of traffic presented by congestion criteria in the existing Project. According to the analysis according to the congestion management standard LOS suggested in this study, Asan city has the most major number of highways where LOS E occurs for more than 3 hours, followed by Sejong City and Gongju City. In addition, when comparing the ratio of the busy main roads according to the frequency of LOS E by city size, it was analyzed that the ratio and extension of the busy highways relative to the overall extension of the large Chungcheong area are similar to the ratio in small cities in the Chungcheong region. Therefore, traffic congestion occurred in small cities and the feasibility of the improvement project was revealed.

A Study on Rate-Based Congestion Control Using EWMA for Multicast Services in IP Based Networks (IP 기반 통신망의 멀티캐스팅 서비스를 위한 지수이동 가중평판을 이용한 전송률기반 폭주제어에 관한 연구)

  • Choi, Jae-Ha;Lee, Seng-Hyup;Chu, Hyung-Suk;An, Chong-Koo;Shin, Soung-Wook
    • Journal of the Institute of Convergence Signal Processing
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    • v.8 no.1
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    • pp.39-43
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    • 2007
  • In high speed communication networks, the determination of a transmission rate is critical for the stability of a closed-loop network system with the congestion control scheme. In ATM networks, the available bit rate (ABR) service is based on a feedback mechanism, i.e., the network status is transferred to the ABR source by a resource management (RM) cell. RM cells contain the traffic information of the downstream nodes for the traffic rate control. However, the traffic status of the downstream nodes can not be directly transferred to the source node in the IP based networks. In this paper, a new rate-based congestion control scheme using an exponential weighted moving average algorithm is proposed to build an efficient feedback control law for congestion avoidance in high speed communication networks. The proposed congestion control scheme assures the stability of switch buffers and higher link utilization of the network. Moreover, we note that the proposed congestion scheme can flexibly work along with the increasing number of input sources in the network, which results in an improved scalability.

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A Packet Dropping Algorithm based on Queue Management for Congestion Avoidance (폭주회피를 위한 큐 관리 기반의 패킷 탈락 알고리즘)

  • 이팔진;양진영
    • Journal of Internet Computing and Services
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    • v.3 no.6
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    • pp.43-51
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    • 2002
  • In this paper, we study the new packet dropping scheme using an active queue management algorithm. Active queue management mechanisms differ from the traditional drop tail mechanism in that in a drop tail queue packets are dropped when the buffer overflows, while in active queue management mechanisms, packets may be dropped early before congestion occurs, However, it still incurs high packet loss ratio when the buffer size is not large enough, By detecting congestion and notifying only a randomly selected fraction of connection, RED causes to the global synchronization and fairness problem. And also, it is the biggest problem that the network traffic characteristics need to be known in order to find the optimum average queue length, We propose a new efficient packet dropping method based on the active queue management for congestion control. The proposed scheme uses the per-flow rate and fair share rate estimates. To this end, we present the estimation algorithm to compute the flow arrival rate and the link fair rate, We shows the proposed method improves the network performance because the traffic generated can not cause rapid fluctuations in queue lengths which result in packet loss

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