• Journal of the Korea Society of Computer and Information
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• v.15 no.4
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• pp.37-45
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• 2010

A system which needs timely accuracy has to design and to verify correctly about execution-time for reliability. Accordingly, it is necessary for timing analysis tools, and much previous research worked. In timing analysis tool, there are two methods. One is a static analysis, and the other is a measurement based analysis. A static analysis is able to spend time less than a measurement based analysis method, but has low reliability of analysis result caused by hard to estimate time of I/O caused by various hardware. A measurement based analysis can be close analysis to real result, but it is hard to adapt to actual application, and spend a lot of time to get result of analysis. As such, this paper present a software monitoring architecture to supply reliability of static analysis process. In a presented architecture, it can select target as needed measurement through static analysis, and reuse result of measurement exist. Therefore, The architecture can reduce overload of time and performance for measurement, and improve the reliability which is the worst problem of static analysis.

• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1058-1070
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• 1999

In this paper, we propose a control model which can control the burst input messages of the BSC(Base Station controller) in mobile communication systems more efficiently and reliably, by dividing the input messages characteristically and using multiprocessor system. Using M/M/c/K queueing model, we briefly analyze proposed model to get characteristic parameters which are required to performance improvement. On the base of the results, we compare our proposed model with the conventional one by using SLAM II with regard to the following factors : the call blocking rate of the input message, the distribution of average queue length, the utilization of process controller(server), and the distribution of average waiting time in queue. In addition, we modified our model which has overload control function for burst input messages, and analyzed its performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.355-367
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• 2013

In the Policy and Charging Control(PCC) architecture of the 3GPP and WiMAX forum, the Policy and Charging Rule Function(PCRF) controls and configures the policies of quality of services(QoS) and accounting to a Policy and Charging Rule Enforcement Function(PCEF). In this paper, we categorize the errors into three types that include a disconnection with peer entity, a delayed or no response and a response with failure result, and propose a scheme to automatically synchronize the data between the PCRF and the PCEF for each type of error. Also, we conduct a quantitative analysis to see how much it can help to maintain the cell capacity of the mobile VoIP service in a WiBro network, which is implemented in Korea according to the standards of WiMAX. We can see that our proposed scheme improves the performances of PCC by preventing the waste of radio resources, the overload of systems, the memory leakage of servers, the system shutdown, and so on. We have validated the scheme by implementation, and reflected it in WiMAX standard documents.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2839-2846
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• 2014

New VHF band for use in VDE is determined by WRC-12 due to the overload of AIS VDL, and the system characteristics of the VDE is recommended as ITU-R M. 1842-1. CS-TDMA, a multiple access method of AIS class B, is recommended as that of the VDE. It is inefficient for CS-TDMA just applying the report interval used in AIS class B to transmit high speed data with higher payload in the aspect of efficiency. In this paper, a simulation is executed in order to determine adequate report interval according to the number of active ships that affects directly network traffic. To this end, the performance of CS-TDMA, which includes the number of received packets, reception success rate, channel utilization, and collision rate, is investigated via a simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1139-1146
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• 2004

An abrupt increase of traffic-load in cellular CDMA systems can cause overload, as a result, degrade the quality of service (QoS) and the spectrum utilization due to lacking radio resources in base stations. In this paper, we propose a joint coverage and resource management (JCRM) scheme which can improve the QoS degradation and the spectrum utilization. The JCRM scheme hands over the overloaded traffic to neighboring cells by virtually reducing overloaded cell coverage and extending neighboring cell coverage, as well the scheme allocates radio resources based on the necessary handover probability. The proposed scheme can be applied to the existing cellular CDMA systems as well as adaptive coverage management schemes for next generation mobile communication systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.672-677
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• 2016

Development of Internet has been successfully inspired with extensive deployment of the network technology and application. However, increases in Internet usage had caused a lot of traffic overload in these days. Thus, we need a continuous research and development on the network virtualization for effective resource allocation. In this paper, we propose a minimal cost virtual network mapping algorithm using Piecewise Linear Cost Function. We exploited an algorithm with Linear Programming and D-VINE for node mapping, and Shortest Path Algorithm based on linear programming solution is used for link mapping. In this way, we compared and analyzed the average cost for arrival rate of VN request with linear and tree structure. Simulation results show that the average cost of our algorithm shows better efficiency than ViNEyard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.348-357
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• 2012

Recently, smartphone, notebook, PC and other supporting wireless LAN device have come into wide use. By increasing user that use wireless LAN device, wireless traffic also increased. If wireless traffic through one AP is increase, it causes throughput decrease. To solve this problem, wireless LAN service provider install more AP where overload occurred. But this is not enough. Because stations can't know AP's load factor, and APs do nothing for load balancing. In this paper, we propose Multi-Interface Access Point(MIAP) to solve this problem. MIAP operate same as multiple APs with multi-interface, and MIAP measure each interface's load periodically. If MIAP detect overloaded interface, MIAP transfer station from overloaded interface to under-loaded interface. We conducted an experiment for verifying existing problem, and we found this problem occurred. We plan an experiment scenario for a comparison between existing AP and MIAP, and excute these experiment. In the result, we show MIAP with load balancing can improve total throughput about 72% and stabilize delay jitter than existing AP.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.891-899
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• 2008

The cdma2000 1xEV-DO system controls the data rates of mobile terminals based on a binary overload indicator from the base station and a simple probabilistic model. However, this traffic control scheme has difficulty in controlling the reverse-link traffic load effectively and in guaranteeing a stable operation of the reverse link because each mobile terminal determines the next data rate autonomously. This paper proposes a new trafRc control scheme to improve the system stability, and analyzes the proposed scheme by modeling it as a discrete-time Markov process. The numerical results show that the maximum data rate of the proposed scheme is much higher than that of the conventional one. Moreover, the proposed scheme does not modify the standard physical channel structure, so it is compatible to the existing 1xEV-DO system.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.5
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• pp.598-606
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• 2002

We suggest a distributed communication and management methodology using PC to PC Query multicasting strategy for efficient management of medical images produced by DICOM(Digital Imaging and Communications in Medicine) Modalities. It is absolutely necessary to reduce strict degradation of PACS system due to large sire of medical images and their very high transport rates. DICOM PC to PC Component is composed of a Service Manager to execute requested queries, a Communication Manager to take charge of file transmission, and a DICOM Manager to manage stored data and system behavior Each Manager itself is a component to search for requested file by interaction or to transmit the file to other PCs. Distributed management and transformation of medical information based on PC to PC Query multicasting methodology will enhance performance of central server and network capacity, reducing overload on both. We organize three major components for system operation. Each component is implemented as Agent. Communication between agents uses XML encoded Agent Communication Language.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1568-1576
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• 2015

This paper proposes a prediction reputation system for the anti-SPIT solution in real-time VoIP environment. Increased accuracy of the determination as to whether spam or not by deriving a threshold based on SPIT presence in the existing paper. The existing schemes need to get the user's feedback and/or have experienced the time delay and overload as session initiates due to real-time operation. To solve these problems, the proposed scheme predicts the reputation through the statistical analysis based on the period of session initiation of each caller and the call duration of each receiver. As per the second mentioned problem, this scheme performs the prediction before session initiation, therefore, it's proper for real-time VoIP environment.