• Journal of Communications and Networks
• /
• v.14 no.5
• /
• pp.578-587
• /
• 2012

One of the key elements in the emerging, packet-based long term evolution (LTE) cellular systems is the deployment of multiple femtocells for the improvement of coverage and data rate. However, arbitrary overlaps in the coverage of these femtocells make the handover operation more complex and challenging. As the existing handover strategy of LTE systems considers only carrier to interference plus noise ratio (CINR), it often suffers from resource constraints in the target femtocell, thereby leading to handover failure. In this paper, we propose a new efficient, multi-objective handover solution for LTE cellular systems. The proposed solution considers multiple parameters like signal strength and available bandwidth in the selection of the optimal target cell. This results in a significant increase in the handover success rate, thereby reducing the blocking of handover and new sessions. The overall handover process is modeled and analyzed by a three-dimensional Markov chain. The analytical results for the major performance metrics closely resemble the simulation results. The simulation results show that the proposed multi-objective handover offers considerable improvement in the session blocking rates, session queuing delay, handover latency, and goodput during handover.

• The KIPS Transactions:PartC
• /
• v.8C no.1
• /
• pp.75-87
• /
• 2001

The Conditional Access System is the complete system for ensuring that broadcasting services are only accessible to those who are entitled to receive them. Four major parts to this system are scrambling, descrambling, authentication and encryption. For the proper operation, which means hard-to- break and uninterrupted service, secure key management and efficient delivery mechanism are very important design factors to this system. Performance analysis is another important factor to this system that is used in massive subscriber environment. In this thesis, one of the secure and efficient key management mechanisms is proposed. For the secrecy of this mechanism, hierarchical stacking of keys and key generation matrix are proposed. For the proof of efficient delivery of those keys, simulation results and performance analysis. which is based on queuing analysis, are presented. Lastly, optimal key generation and delivery period, maximal and minimal key deliver time, and communication capacity for data collection are presented for various subscriber volume.

• 제어로봇시스템학회:학술대회논문집
• /
• 1986.10a
• /
• pp.169-174
• /
• 1986

This thesis investigates the scanning time ; one of the most important performance index of Programmable Controller(PC). The multiprocessor architecture of the large PC considered in this thesis are classified as architecture 1 and architecture 2 by the bus control methods. The queuing model of each architecture is developed. Form the analysis it is observed that in the case of the number of processors less than 3 the best architecture of the large PC is the architecture 2 and in the case of the number of processors greater than 2 the best architecture of the large PC is the architecture 1.

• Proceedings of the Korea Contents Association Conference
• /
• 2018.05a
• /
• pp.511-512
• /
• 2018

Virtual machine technology enables multiple hosts to share the same LUN(Logical Unit Number) and the same storage, but if too many hosts share the same LUN, it will increase the delay. In this paper we propose a performance model, get several values of scalable storage performance in virtual environment, and present the results examined the effects of I/O queuing in a virtual infrastructure. This results show how to make the most effective use of our storage resources.

• Journal of the Korea Society for Simulation
• /
• v.1 no.1
• /
• pp.31-36
• /
• 1992

To estimate the probability of long delay in a queuing system using discrete-event simulation is studied. We contrast the coverage, half-width, and stability of confidence intervals constructed using two methods: batch means and new resampling technique; binary bootstrap. The binary bootstrap is an extension of the conventional bootstrap that resamples runs rather than data values. Empirical comparisons using known results for the M/M/1 and D/M/10 queues show the binary bootstrap superior to batch means for this problem.

• Proceedings of the Korea Society for Simulation Conference
• /
• 1992.10a
• /
• pp.13-13
• /
• 1992

To estimate the probability of long delay in a queuing system using discrete-event simulation studied. We contrast the coverage, half-width, and stability of confidence intervals constructed using two methods: batch means and new resampling technique; binary bootstrap. The binary bootstrap is an extension of the conventional bootstrap that resamples runs rather than data values. Empirical comparisons using known results for the M/M/1 and D/M/10 queues show the binary bootstrap superior to batch means for this problem.

• Journal of KIISE:Computer Systems and Theory
• /
• v.35 no.11
• /
• pp.527-539
• /
• 2008

This paper presents a performance estimation technique based on queuing analysis for on-chip bus matrix architectures of Multi-Processor System-on-Chips(MPSoCs). Previous works relying on time-consuming simulation are not able to explore the vast design space to cope with increasing time-to-market pressure. The proposed technique gives accurate estimation results while achieving faster estimation time than cycle -accurate simulation by order of magnitude. We consider the followings for the modeling of practical memory subsystem: (1) the service time with the general distribution instead of the exponential distribution and (2) multiple-outstanding transactions to achieve high performance. The experimental results show that the proposed analysis technique has the accuracy of 94% on average and much shorter runtime ($10^5$ times faster at least) compared to simulation for the various examples: the synthetic traces and real-time application, 4-channel DVR.

• Journal of Korean Society of Transportation
• /
• v.26 no.1
• /
• pp.15-24
• /
• 2008

Located in the middle of lanes, the station of a median exclusive bus lane generates pedestrian groups on the green light of a crosswalk and causes pedestrians delays passing the access section. For the purpose of showing these facts, the pedestrian analysis, on which the queuing theory is applied, is presented in this study. The Result is that the pedestrian environment was deteriorated (LOS D) compared to an exciting pedestrian analysis based on 15 minutes of pedestrian volume (LOS A). A pedestrian level of service has been reevaluated based on an arrival rate on the median bus station in order to examine whether the result reflects reality or not. In result, it was similar outcomes to this study.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.6
• /
• pp.11-16
• /
• 2009

The queuing theory was adopted by Erlang to predict the availability of telephone lines in 1917 and had not been used for computer system performance analysis until late 1960s when Scherr published a performance analysis of time-shared computer system. In 2000s, the explosive Internet usage and the development of IT technology made the business environment speed-centric and analysts should react swiftly to the ever-changing situation to satisfy the user requirement. It's tempting to solve the performance problem by purchasing new devices because the price of computers and peripherals are rapidly decreasing along with their increasing performance. But this scheme not only makes it difficult to understand the overall performance of the system but also wastes money. A coarse performance model that is gotten quickly is sometimes preferred to a complex and precise one that takes longer time to get. This paper examines an analytic model suggested by Menasce based on the measured data and suggests a simulation model using ARENA that takes a short time to build.

• Convergence Security Journal
• /
• v.22 no.4
• /
• pp.17-24
• /
• 2022

Recently, machine learning-based cyber attack detection and classification research has been actively conducted, achieving a high level of detection accuracy. However, low-spec IoT devices and large-scale network traffic make it difficult to apply machine learning-based detection models in IoT environment. Therefore, In this paper, we propose an efficient IoT attack detection and classification method through PCA(Principal Component Analysis) and LightGBM(Light Gradient Boosting Model) using datasets collected in a MQTT(Message Queuing Telementry Transport) IoT protocol environment that is also used in the defense field. As a result of the experiment, even though the original dataset was reduced to about 15%, the performance was almost similar to that of the original. It also showed the best performance in comparative evaluation with the four dimensional reduction techniques selected in this paper.