• ETRI Journal
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• v.28 no.1
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• pp.31-44
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• 2006

In a packet switching network, congestion is unavoidable and affects the quality of real-time traffic with such problems as delay and packet loss. Packet fair queuing (PFQ) algorithms are well-known solutions for quality-of-service (QoS) guarantee by packet scheduling. Our approach is different from previous algorithms in that it uses hardware time achieved by sampling a counter triggered by a periodic clock signal. This clock signal can be provided to all the modules of a routing system to get synchronization. In this architecture, a variant of the PFQ algorithm, called digitized delay queuing (DDQ), can be distributed on many line interface modules. We derive the delay bounds in a single processor system and in a distributed architecture. The definition of traffic contribution improves the simplicity of the mathematical models. The effect of different time between modules in a distributed architecture is the key idea for understanding the delay behavior of a routing system. The number of bins required for the DDQ algorithm is also derived to make the system configuration clear. The analytical models developed in this paper form the basis of improvement and application to a combined input and output queuing (CIOQ) router architecture for a higher speed QoS network.

• Journal of applied mathematics & informatics
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• v.3 no.2
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• pp.193-204
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• 1996

Overflow queuing models are ofter analyzed by explicitly solving a large sparse singular linear systems arising from Kolmogorov balance equation. The system is often converted into an eigenvalue problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem into an overflow queuing problem into an eigen-value problem into an eigen-value problem of size 1/2 of the original. Then we devise an orthogonal projector that enhances its convergence by removing unsanted eigen-components effectively. Numerical result with some suggestion is given at the end.

• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.354-363
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• 2016

Due to uncertain environment, various parameters such as price, queuing length, warranty, and so on influence on inventory models. In this paper, an inventory-queuing-pricing problem with continuous review inventory control policy and batch arrival queuing approach, is presented. To best of our knowledge, (I) demand function is stochastic and price dependent; (II) due to the uncertainty in real-world situations, a fuzzy programming approach is applied. Therefore, the presented model with goal of maximizing total profit of system analyzes the price and order quantity decision variables. Since the proposed model belongs to NP-hard problems, Pareto-based approaches based on non-dominated ranking and sorting genetic algorithm are proposed and justified to solve the model. Several numerical illustrations are generated to demonstrate the model validity and algorithms performance. The results showed the applicability and robustness of the proposed soft-computing-based approaches to analyze the problem.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.222-227
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• 2013

This paper presents an analytical framework for dynamic spectrum allocation in cognitive radio networks. We propose a distributed queuing based Markovian model each for single channel and multiple channels access for a contending user. Knowledge about spectrum mobility is one of the most challenging problems in both these setups. To solve this, we consider probabilistic channel availability in case of licensed channel detection for single channel allocation, while variable data rates are considered using channel aggregation technique in the multiple channel access model. These models are designed for a centralized architecture to enable dynamic spectrum allocation and are compared on the basis of access latency and service duration.

• Journal of Communications and Networks
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• v.13 no.3
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• pp.286-297
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• 2011

A novel converged optical network unit (ONU)-base station (BS) architecture has been contemplated for next-generation optical-wireless networks. It has been demonstrated through high quality studies that data traffic carried by both wired and wireless networks exhibit self-similar and long range dependent characteristics; attributes that classical teletraffic theory based on simplistic Poisson models fail to capture. Therefore, in order to apprehend the proposed converged architecture and to reinforce the provisioning of tightly bound quality of service (QoS) parameters to end-users, we substantiate the analysis of the QoS behavior of the ONU-BS under self-similar and long range dependent traffic conditions using custom queuing which is a common queuing discipline. This paper extends our previous work on priority queuing and brings novelty in terms of presenting performance analysis of the converged ONU-BS under realistic traffic load conditions. Further, the presented analysis can be used as a network planning and optimization tool to select the most robust and appropriate queuing discipline for the ONU-BS relevant to the QoS requirements of different applications.

• Industrial Engineering and Management Systems
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• v.12 no.3
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• pp.274-280
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• 2013

This paper proposes a space merging approach to studying the queuing models with finite buffers and jump priorities. Upon the arrival of a call with low priority, one call of such kind is assumed to be transferred to the end of the queue of high priority calls. The transfer probabilities depend on the state of the queue of the heterogeneous calls. We developed the algorithms to calculate the quality of service metrics of such queuing models, and the results of the numerical experiments are shown.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2450-2469
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• 2018

In this paper, we develop a spatiotemporal model to analysis of cellular user in underlay D2D communication by using stochastic geometry and queuing theory. Firstly, by exploring stochastic geometry to model the user locations, we derive the probability that the SINR of cellular user in a predefined interval, which constrains the corresponding transmission rate of cellular user. Secondly, in contrast to the previous studies with full traffic models, we employ queueing theory to evaluate the performance parameters of dynamic traffic model and formulate the cellular user transmission mechanism as a M/G/1 queuing model. In the derivation, Embedded Markov chain is introduced to depict the stationary distribution of cellular user queue status. Thirdly, the expressions of performance metrics in terms of mean queue length, mean throughput, mean delay and mean dropping probability are obtained, respectively. Simulation results show the validity and rationality of the theoretical analysis under different channel conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.664-682
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• 2012

To improve the accuracy and enhance the applicability of existing models, this paper proposes a generalized Markov chain model for IEEE 802.11 Distributed Coordination Function (DCF) under the widely adopted assumption of ideal transmission channel. The IEEE 802.11 DCF is modeled by a two dimensional Markov chain, which takes into account unsaturated traffic, backoff freezing, retry limits, the difference between maximum retransmission count and maximum backoff exponent, and limited buffer size based on the M/G/1/K queuing model. We show that existing models can be treated as special cases of the proposed generalized model. Furthermore, simulation results validate the accuracy of the proposed model.

• Journal of the Korea Society for Simulation
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• v.9 no.3
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• pp.65-75
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• 2000

In recent years, significant advances in computers and communication technologies have made multimedia services feasible. As a result, various queuing models and cost models on architecture and data placement for multimedia server have been proposed. However, these analytical techniques use only probabilistic models to represent the behavior of a system, and then they have several limitations like accuracy. Simulation is a viable alternative to analytical model. It avoids many of the limitations associated with analytical techniques, allowing for more precise representation of system attributes like workload in program code. In this paper, we propose a simulation test bed that can evaluate performance of real-time multimedia server by using simulation model.

• Journal of KIBIM
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• v.5 no.2
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• pp.1-11
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• 2015

Despite a lot of research on BIM, there is no quantitative study to measure accurately the performance of BIM coordination service. Thus, this study suggested method to measure the performace of BIM coordination services, applying queueing models in the field of management science. To analyze queuing system of BIM coordination services, a group of BIM coordinator were selected. Through focus group interviews with experts were used in the analysis to derive mean arrival rate(${\lambda}$), mean service rate(${\mu}$) of BIM coordination services. Single-server queuing model(M/M/1), multiple server queuing model(M/M/s) is utilized for the BIM coordination services performance measurement in construction phase. This study has significant quantitative performance measurement approaches that can be utilized in the decision-making for the improvement of the BIM coordination services and to support the review of the alternatives accordingly. But There is a limit but it is difficult to take into account the increase or decrease of the cost of alternatives according to the review.