• Title/Summary/Keyword: Queueing Delay

Search Result 169, Processing Time 0.025 seconds

A Study on the Optimal Order of Queueing System with three Stations (세개의 창구로 구성된 큐잉시스템의 최적순서에 관한 연구)

  • 조한벽;김재련
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.14 no.24
    • /
    • pp.149-154
    • /
    • 1991
  • The one of the important problems in the design of queueing systems is the decision of the order of service stations. The object of this problem is the decision of the order that minimizes the expected sojourn time per customer in the given arrival process and service time distributions. In this paper, the tandem queueing system in series is studied with the emphasis on the optimal order of the tandem queueing system which has three stations with single servers. In one system, customers arrive at the first station with Poisson process. This system is composed of service stations with a constant, a general distribution and a Exponential distribution is studied. To select the optimal order after the orders of each pair of two stations is decided, it is compared the two orders of system. With this results, total expected delay of the systems which has three stations is compared. The result is the best that service station with constant time is on the first place, then the service station with general distribution and the service station with Exponential distribution is followed. And the other system is consist of service stations with a constant and two probabilistic distributions. In this case, two probabilistic distributions has a non-overlapping feature. It is the optimal order that the service station with constant time is on the first place then the service station with longer service time and the service station with shorter service time is followed.

  • PDF

Multiaccess Scheme with Implicit Reservation for VSAT Data commmunication (VSAT 데이터 통신을 위한 묵시적 예약 방식의 다중접속 기법)

  • 이창건;최양희;정선종;김종상
    • Journal of the Korean Institute of Telematics and Electronics A
    • /
    • v.31A no.7
    • /
    • pp.1-16
    • /
    • 1994
  • In this paper, we propose a new multiple access scheme for VSAT(Very Small Aperture Terminal) data communications. The proposed scheme has better performance in terms of delay throughput than Controlled Multiaccess Scheme which has excellent performance. The proposed scheme use the spare reservation method, adaptation method to offered load, and fixed bandwidth reservation method. In this paper, we analyze the performance using simple queueing model and present the simulation results. When network traffic is very low, the new scheme and the controlled multiaccess scheme have almost the same access delay characteristic. As the network load becomes higher, the new scheme's access delay gain becomes larger. Futhermore, even when the network traffic is very high it is possible to access satellite link within the delay similar to one round-trip delay. In addition to access delay performance enhancement, the new scheme has facility that supports fixed bandwidth reservation. So it shows more enhanced performance in the environment that stream traffic is dominant such as in VSAT communication environment.

  • PDF

A Study of Optimal Group Number to Minimize Average Paging Delay (최소 평균 페이징 지연을 위한 최적의 페이징 그룹 수에 관한 연구)

  • Lee, Goo-Yeon
    • Journal of Industrial Technology
    • /
    • v.25 no.B
    • /
    • pp.221-229
    • /
    • 2005
  • We present a numerical analysis of the optimal group number for minimizing the average paging delay. In the analysis, we consider uniform distributions for location probability conditions and apply M/D/1 queueing model to paging message queues of cells. We also get the lower bounds of group numbers and investigate the minimum transmission capacity under average paging delay constraints. Minimizing the average paging delay is important because it means minimizing the amount of bandwidth used for locating mobile terminals. Therefore, the numerical results of this paper will be very useful in PCS system when designing its signalling capacity due to its simplicity and effectiveness.

  • PDF

An Analysis of Ship Turnaround Time in the Port of Inchon (선박재항시간에 대한 분석연구 -인천항의 경우-)

  • Baik, In-Hum
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.10 no.1
    • /
    • pp.1-14
    • /
    • 1998
  • Transportation provides an infrastructure vital to economic growth, and it is also an integral part of production. As a port is regarded as the interface between the maritime transport and domestic transport sectors, it certainly play a key role in any economic development. Ship's delay caused by port congestion has recently has recently attracted attended with the analysis of overall operation in port. In order to analyse complicated port operation which contains large number of variable factors, queueing theory is needed to be adopted, which is applicable to a large scale transportation system in chiding ship's delay in Inchon port in relation to ship's delay problem. The overall findings are as follows ; 1. The stucture of queueing model in this port can be represented as a complex of multi-channel single-phase 2. Ship's arrival and service pattern were Poisson Input Erlangian Service. 3. The suitable formula to calculate the mean delay in this port, namely, $W_q={\frac{{\rho}}{{\lambda}(1-{\rho})}}{\frac{e{\small{N}}({\rho}{\cdot}N)}{D_{N-1}({\rho}{\cdot}N)}}$ Where, ${\lambda}$ : mean arrival rate ${\mu}$ : mean servicing rate N : number of servicing channel ${\rho}$ : utilization rate (l/Nm) $e{\small{N}}$ : the Poisson function $D_{(n-1)}$ : a function of the cumulative Poisson function 4. The utility rate is 95.0 percents in general piers, 75.39 percents in container piers, and watiting time 28.43 hours in general piers, 13.67 hours in container piers, and the length of queue is 6.17 ships in general piers, 0.93 ships in container piers, and the ship turnaround time is 107.03 hours in general piers, 51.93 hours in container piers.

  • PDF

Self-Healing Algorithm for The Restoration of Synchronous Optical Networks (동기식 광전송망 복구를 위한 자체 치유 알고리즘)

  • 장윤선;지윤규;김홍주
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.19 no.6
    • /
    • pp.1158-1168
    • /
    • 1994
  • The paper proposes a distributed control self-healing algorithm for a line failure to improve the restoration time. This proposed self-healing algorithm acquired the fast restoration time by reducing the number of control messages and the queueing delay. And the reduction of queueing delay was attained by the ASC_NULL(Available Spare Channel_NULL) message which informs neighbor nodes that a source node has no available spare channel to reduce the waste of time during the rerouting. It is difficult for this proposed self-healing algorithm to be compared with other self-healing algorithms, because each self-healing algorithm has different simulation conditions. So, the performance of the proposed self-healing algorithm was compared with only NETRATS(NETwork Restoration Algorithm for Telecommunication Systems). The results of the simulation showed that the proposed self-healing algorithm was better than NETRATS in the restoration time.

  • PDF

Packet scheduling algorithm for guaranteed bound and firewall property of delay performance (지연의 상한 보장과 안정성을 고려한 패킷 스케쥴링 알고리즘)

  • 정대인
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.27 no.5C
    • /
    • pp.435-444
    • /
    • 2002
  • In this paper, a novel packet scheduling algorithm, so-called the CSL algorithm is discussed, whereby the firewall property as well as the deterministic delay bound guarantee are supported in session level. Lots of simulation studies validate those properties of the CSL algorithm. The CSL algorithm is distingushable from the well- known EDD scheme in terms of the firewall property. Regarding the implementation complexity, the CSL algorithm turns out to be of 0(1) besides the sorting overhead. Owing to the maintained generic fair queueing structure in the CSL algorithm, a various fair queueing schemes can be applied with minor modification. For the TCP/IP network which is vulnerable to the misbehaving traffic sources, the firewall property of the CSL algorithm is quite useful for the advanced quality of services.

A New Queue Management Algorithm for Improving Fairness between TCP and UDP Flows (TCP와 UDP 플로우 간의 공정성 개선을 위한 새로운 큐 관리 알고리즘)

  • Chae, Hyun-Seok;Choi, Myung-Ryul
    • The KIPS Transactions:PartC
    • /
    • v.11C no.1
    • /
    • pp.89-98
    • /
    • 2004
  • AQM (Active Queue Management) techniques such as RED (Random Early Detection) which be proposed to solve the congestion of internet perform congestion control effectively for TCP data. However, in the situation where TCP and UDP share the bottleneck link, they can not solve the problems of the unfairness and long queueing delay. In this paper, we proposed an simple queue management algorithm, called PSRED (Protocol Sensitive RED), that improves fairness and decreases queueing delay. PSRED algorithm improves fairness and decreases average queue length by distinguishes each type of flow in using protocol field of packets and applies different drop functions to them respectively.

An Impact Analysis of Window Mechanism and End to End Delay of Tandem Queueing Network with Constant Service Times (상수 서비스 시간을 갖는 개방형 대기행렬의 종대종 지연과 윈도우 구조의 영향 분석)

  • Rhee Young
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.29 no.3
    • /
    • pp.99-109
    • /
    • 2004
  • In this paper, we investigate the impact of window mechanisms on end to end delay in a series of nodes with constant service times. It is shown that arbitrary combinations of window mechanisms, each applying to an arbitrary subset of data, can be embedded on the nodes without affecting the departure instants from the system if the windows are at least as large as the number of nodes spanned. The window mechanisms are shown to have no impact on the average end to end delay of data. As the condition on the windows is a minimal necessary requirement for full parallelism, the results show that the transparent operation from viewpoint of data transmission can be achieved with minimal resources.

Comparison of Delay Estimates for Signalized Intersection (신호교차로 지체 산정 비교)

  • Jo, Jun-Han;Jo, Yong-Chan;Kim, Seong-Ho
    • Journal of Korean Society of Transportation
    • /
    • v.23 no.1
    • /
    • pp.67-80
    • /
    • 2005
  • In this paper, the primary objective of the research are to review the methods currently avaliable for estimating the delay incurred by vehicles at signalized intersections. The paper compares the delay estimates from a deterministic queueing model, a model based on shock wave theory , the steady-state Webster model, the queue-based models defined in the 1994 and 2001 version of the High way Capacity Manual, in addition to the delays estimated from the TRANSYT-7F macroscopic simulation and NETSIM microscopic simulation. More especially, this paper is to compare the delay estimates obtained using macroscopic and microscopic simulation tools against state-of-the practice analytical models that are derived from deterministic queueing and shock wave analysis theory. The results of the comparisons indicate that all delay models produce relatively similar results for signalized intersections with low traffic demand, but that increasing differences occur as the traffic demand approaches saturation. In particular, when the TRANSYT-7F and NETSIM are compared, it is highly differences as approach for traffic condition to over-saturation. Also, the NETSIM microscopic simulation is the lowest estimates among the various models.

Space and Time Priority Queues with Randomized Push-Out Scheme (확률적 밀어내기 정책을 가지는 공간-시간 우선순위 대기행렬)

  • Kilhwan Kim
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.46 no.2
    • /
    • pp.57-71
    • /
    • 2023
  • In this study, we analyze a finite-buffer M/G/1 queueing model with randomized pushout space priority and nonpreemptive time priority. Space and time priority queueing models have been extensively studied to analyze the performance of communication systems serving different types of traffic simultaneously: one type is sensitive to packet delay, and the other is sensitive to packet loss. However, these models have limitations. Some models assume that packet transmission times follow exponential distributions, which is not always realistic. Other models use general distributions for packet transmission times, but their space priority rules are too rigid, making it difficult to fine-tune service performance for different types of traffic. Our proposed model addresses these limitations and is more suitable for analyzing communication systems that handle different types of traffic with general packet length distributions. For the proposed queueing model, we first derive the distribution of the number of packets in the system when the transmission of each packet is completed, and we then obtain packet loss probabilities and the expected number of packets for each type of traffic. We also present a numerical example to explore the effect of a system parameter, the pushout probability, on system performance for different packet transmission time distributions.