• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8B
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• pp.681-688
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• 2008

In this paper, we propose a new price-based call admission control algorithm for multi-class communication networks. When a call arrives at the network, it informs the network of the number of requested circuits and the minimum amount of time that it will require. The network provides the optimal price for the arrived call with which it tries to maximize its expected revenue. The optimal price is dynamically adjusted based on the information of the arrived call, and the present and the estimated future congestion level of the network during the reservation time of the call. If the call accepts the price, it is admitted. Otherwise, it is rejected. We compare the performance of our dynamic pricing algorithm with that of the static pricing algorithm by Courcoubetis and Reiman [1], and Paschalidis and Tsitsiklis [2]. By the comparison, we show that our dynamic pricing algorithm has better performance aspects such as higher call admission ratio and lower price than the static pricing algorithm, although these two algorithms result in almost the same revenue as shown in [2]. This implies that, in the competitive situation, the dynamic pricing algorithm can attract more users than the static pricing algorithm, generating more revenue. Moreover, we show that if a certain fixed connection fee is introduced to the price for a call, our dynamic pricing algorithm yields more revenue.

• ICROS
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• v.3 no.2
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• pp.41-50
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• 1997

본 논문에서는 무궁화위성의 발사단계에서부터 궤도상 운용에 이르기까지 각 임무 단계별로 필요한 궤도제어 기법을 살펴보았다. 정지궤도 통신/방송 위성은 정지궤도 진입 및 정지궤도상에서 임무 수행을 위한 정밀 궤도 제어 등 궤도제어와 관련하여 궤도 결정과 함께 지상국용 임무설계 S/W를 필요로 한다. 정지궤도 위성의 이러한 궤도 제어 기술은 향후 국내의 자체 정지궤도 위성 개발시 관련 기술의 국산화에 많은 도움이 될 것으로 기대된다. 또한 현재 무궁화위성 1, 2호의 운용기술을 자체 습득하고 고도화하는 노력도 향후 계속되는 국내 수요에 대비하여 계속되어야 할 것이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.127-128
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• 2022

자율운항선박의 육상원격제어시스템 개발을 위해 선박제어 모사장치를 이용한 원격제어장치, 원격모니터링, 통신시스템에 대한 개발 현황을 나열하고 향후 기능개선 개발 방향을 제시하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.65-66
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• 2022

자율운항선박의 육상원격제어시스템 개발을 위해 선박제어 모사장치를 이용한 원격제어장치, 원격모니터링, 통신시스템에 대한 개발 현황을 나열하고 향후 개선 방안을 제시하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7B
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• pp.440-449
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• 2005

This paper proposes the measurement scheme for network overload and the control technique in case of breaking several control channels when we support the call services of DAMA through communication satellite(GEO, Geostationary Earth Orbit). And its performance is analyzed. The proposed schemes measure the overload of access control channel of a network controller to control the call connections, detect the level of network overload, notify the terminals of DAMA network of the state, and excute overload control. As a result, it improves the system performance and the network stability at overload state. Moreover hysteresis is applied to the change of overload state for the restriction of the frequent state shifts. The results show that the proposed algorithm prevents excessive increment of call-setup delay and too much lowering of call success rate, and improves the network stability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1013-1021
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• 2004

In the WCDMA mobile multimedia communication system, the adaptive array antenna IS adopted to improve the performance of the system by reducing inter-user interference using antenna beam control. Usually, the interference resulted from the higher data rate users is much more significant to the lower data rate users than the other way around, so the overall performance can be enhanced by reducing the interference from higher data rate users. In order to maximize the efficiency of adaptive antenna operation, an optimal call admission control, especially during handoff, adaptive to the data rates is a critical problem. In this paper, We propose a call admission control algorithm based on the Soft QoS concept for the efficient processing of the handoff of higher data rate calls, and an adaptive handoff control mechanism according to the data rates. The proposed algorithm has been evaluated by computer simulation that it accommodates high data rate users among many lower data rate users much better, and the average call blocking probability for lower rate users becomes much lower than the conventional call admission control algorithm.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.372-377
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• 2009

This paper evaluates the performance of three methods for predicting resources requested by mobile's calls and a call admission algorithm based on these predicting methods respectively in wireless networks. The first method is based on Wiener prediction model and the second method is based on the MMOSPRED algorithm and the third method is based on the neural network. The proposed call admission algorithm is based on prioritized handoff call in resource allocation. The resources for future handoff calls are therefore predicted and reserved in advance, and then new calls are admitted as long as the remaining resources are sufficient. We compare their performances in terms of prediction error, new call blocking and handoff dropping probabilities by simulation. Results show that the CAC based on Wiener prediction model performs favorably due to exact resources prediction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.9
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• pp.1-11
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• 2001

Most handoff control schemes try to offer the negotiated QoS by resource reservation for handoff calls. However, it is very difficult to determine the optimal amount of reservation resource for the handoff calls, and sometimes a considerable waste of network resource may be caused. In order to solve this problem, we propose a 2-level resource reservation and call admission control scheme. In our scheme, handoffs are classified into two types (primary and secondary) based on how often they occur and are dealt with in different ways. Simulation results show that our scheme may allow more efficient utilization of network resource without degrading QoS comparing with the existing with legacy handoff control scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3B
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• pp.232-238
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• 2006

We propose a novel call admission control scheme which improves the handoff drop and the new call block probabilities of high priority services, minimizing the negative impact on low priority services, in multimedia service cellular networks. This paper proposes three schemes to solve this problem; the packing scheme in which available channels of a cell distributed to each frequency channel are concentrated on one frequency channel and a high transmission rate service is assigned to the frequency channel; the queuing scheme in which the queue is used for high transmission rate calls; and the power reallocation scheme in which the power assigned to calls under service is temporarily reduced and a high transmission rate service is allowed. The simulation results revealed that our scheme improved the drop and the block probabilities of the high priority services compared with the conventional scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.535-542
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• 2006

A large signal stability analysis of the solar array regulator system is performed to facilitate the design and analysis of a Low-Earth-Orbit satellite power system. The effective load characteristics of every controllable method in the solar array system are classified to analyze the large signal stability. Then, using the state plane analysis technique, the stability of various equilibrium points is analyzed. A nonlinear transformation algorithm, which changes the effective load characteristic of the solar array regulator as constant resistive load, is also proposed for the large signal stability. The proposed resistive current mode control system can control the solar array output for purposes such as peak power tracking control and battery charging control. For the verification of the proposed large signal analysis and resistive current mode control, a solar array regulator system consisting of two 100W parallel module buck converters has been built and tested using a real 200W solar array.