• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.6
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• pp.722-728
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• 2003

In this paper, we propose a fuzzy traffic controller of Sugeno`s fuzzy model so as to model the nonlinear characteristics of controlling the traffic light. It use a degree of the traffic congestion of the preceding roads as an input so that it can cope with traffic congestion appropriately, which causes the loss of fuel and our discomfort. First, in order to construct fuzzy traffic controller of Sugeno`s fuzzy model, we model the control process of the traffic light by using Mamdani`s fuzzy model, which has the uniform membership functions of the same size and shape. Second, we make Mamdani`s fuzzy model with the non-uniform membership functions so that it can exactly reflect the knowledge of experts and operators. Last, we construct the fuzzy traffic controller of Sugeno`s fuzzy model by learning from the input/output data, which is retrieved from Mamdani`s fuzzy model with the non-uniform membership functions. We compared and analyzed the fixed traffic light controller, the fuzzy traffic controller of Mamdani`s fuzzy model and the fuzzy traffic controller of Sugeno`s fuzzy model by using the delay time and the proportion of the entered vehicles to the occurred vehicles. As a result of comparison, the fuzzy traffic controller of Sugeno`s fuzzy model showed the best performance.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.664-667
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• 2003

We propose a frizzy traffic controller of Sugeno's fuzzy model so as to model the nonlinear characteristics of controlling the traffic light. It uses a degree of the traffic congestion of the preceding roads as an input so that it can cope with traffic congestion appropriately, which causes the loss of fuel and our discomfort. In order to construct fuzzy traffic controller of Sugeno's fuzzy model we first model the control process of the traffic light by using Mamdani's fuzzy model, which has the uniform membership functions of the same size and shape. Next we make Mamdani's fuzzy model with the non-uniform membership functions so that it can exactly reflect the knowledge of experts and operators. Lastly, we construct the fuzzy traffic controller of Sugeno's fuzzy model by learning from the input/output data, which is retrieved from Mamdani's fuzzy model with the non-uniform membership functions. We compared and analyzed the service level of the traffic light controllers by using the delay time. As a result of comparison, the fuzzy traffic controller of Sugeno's fuzzy model shows the best service level of them.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.249-257
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• 2003

Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1828-1835
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• 2000

In this paper, we analyzed the other-cell interference characteristics for various non-uniform traffic distributions and their effects on the capacity of multi-cell CDMA system. We consider three different traffic distributions, i.e., linear, exponential and Gaussian traffic distribution with distribution parameters. Changing the distribution parameter, we can obtain the center-focused distributions or uniform distributions for each model. From the results of other-cell interference calculation we can see that the other-cell interference decreases, as the user concentrates on the base station. Also using frequency reuse efficiency indicating the capacity reduction of a multi-cell system when compared to a single cell system, we evaluate the effect of traffic distribution on the reverse link CDMA capacity. For linear case, the capacity of multi-cell system is reduced to 0.637∼0.867 times that of single cell system. On the other hand, for both exponential and Gaussian cases, the capacity under a multi-cell environment is equal to 70∼100% of that under a single cell. Therefore, we conclude that the average capacity of multi-cell CDMA system are increased when users are likely to be at near the cell base station due to reduced total other-cell interference and decreased when users exist at near the cell edge regardless of traffic distribution models.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.33-39
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• 1997

In this paper we proposed a new traffic load shedding scheme which maximizes the throughput of traffic control by decreasing the load of the hot-spot cell using minimum load cell selection (MLCS) algorithm and deployed control flow of calls to define characteristic for hadoff region. we compared the performance of the random shedding approach with that of the proposed algorithm. The results of simulation show that MLCS algorithm minimizes the cal blocking rate under a high-density traffic compared to the random shedding scheme.

• Management Science and Financial Engineering
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• v.4 no.2
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• pp.43-58
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• 1998

Packet switch is a key component in high speed digital networks. This paper investigates congestion phenomena in the packet switching with input buffers. For large value of switch size N, mathematical models have been developed to analyze asymptotic maximum switch throughput under nonuniform traffic. Simulation study has also been done for small values of finite N. The rapid convergence of the switch performance with finite switch size to asymptotic solutions implies that asymptotic analytical solutions approximate very closely to maximum throughputs for reasonably large but finite N. Numerical examples show that non-uniformity in traffic pattern could result in serious degradation in packet switch performance, while the maximum switch throughput is 0.586 when the traffic load is uniform over the output trunks. Window scheduling policy seems to work only when the traffic is relatively uniformly distributed. As traffic non-uniformity increases, the effect of window size on throughput is getting mediocre.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1387-1394
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• 2005

In this paper, we propose and the call admission control mechanism that can improve the capacity of the wireless system for the non-uniform traffic load distribution based intelligent information in multiple cellular CDMA environment. The number of mobile stations that can be served simultaneously in a base station is limited by the amount of total interference received in CDMA system. Further, the average number of mobile stations in each cell may not be uniformly distributed. In this paper, considering this factors, the call admission control mechanism using the effective bandwidth concept is adapted to improve the system capacity of non-uniform traffic load distribution based intelligent information. Thus, the bandwidth for a new call can be varied dynamically for reducing the blocking rate of new calls and the dropping rate of handoff calls. The suggested call admission control mechanism is experimented through simulation by dynamically assigning the bandwidth to new and handoff calls. The simulation results show that the proposed call admission control mechanism can accommodate more mobile stations than the other methods in multiple cellular CDMA environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.316-323
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• 2002

In this paper, we analyze the call control scheme that is using buffer at new call and handoff call for non-uniform traffic load distribution, the multiple cell environments and the multiple types of services such as voice and data service. Considering the facts, the call admission control method using the effective bandwidth concept is employed in this paper, The bandwidth for a new call and a handoff call is allocated by the number of mobile station and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. The call control procedure is experimented through a simulation study by dynamically the bandwidth to new and handoff calls based on the blocking rate and the dropping rate. The results show our call control scheme can get a good quality of service for mobile users.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2302-2324
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• 2014

Cluster-based wireless sensor network (WSN) can significantly reduce the energy consumption by data aggregation and has been widely used in WSN applications. However, due to the intrinsic many-to-one traffic pattern in WSN, the network lifetime is generally deteriorated by the unbalanced energy consumption in a cluster-based WSN. Therefore, energy efficiency and network lifetime improvement are two crucial and challenging issues in cluster-based WSNs. In this paper, we propose a Non-Uniform Node Distribution (NUND) scheme to improve the energy efficiency and network lifetime in cluster-based WSNs. Specifically, we first propose an analytic model to analyze the energy consumption and the network lifetime of the cluster-based WSNs. Based on the analysis results, we propose a node distribution algorithm to maximize the network lifetime with a fixed number of sensor nodes in cluster-based WSNs. Extensive simulations demonstrate that the theoretical analysis results determined by the proposed analytic model are consistent with the simulation results, and the NUND can significantly improve the energy efficiency and network lifetime.

• ETRI Journal
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• v.38 no.3
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• pp.463-468
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• 2016

With the constant increase in network traffic, wireless operators are finding it more challenging to keep network hardware costs to a minimum. At the same time, the energy cost associated with operating a network has increased proportionally. Therefore, the search for higher network capacity is simultaneously accompanied by the search for a cost-efficient network deployment. In this paper, we show that a saving in transmitted signal energy can be achieved at the signal design level by deploying very specific signal processing techniques. Using an orthogonal frequency-division multiplexing signal for Long-Term Evolution networks as an example, we utilize a novel non-uniform companding quantizer to save a transmitted signal energy. Our results show that by using non-uniform quantization it is possible to further optimize 4G wireless networks.