• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.288-292
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• 2004

Recently the application area of wireless LAN has been increased, rapidly. The application area was limited in indoor, but as the data throughput and performance of wireless LAN becomes better the application is to extend to the Internet connection and wireless bridge in outdoor. In this paper, the data throughput of wireless LAN in mobile environment is measured, and the usability of wireless LAN for ITS, Telematics, and LBS is confirmed.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.395-396
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• 2007

Recently the application area of wireless LAN has been increased, rapidly. The application area was limited in indoor, but as the data throughput and performance of wireless LAN becomes better the application is to extend to the Internet connection and wireless bridge in outdoor. In this paper, the data throughput of wireless LAN in mobile environment is measured, and the usability of wireless LAN for Train, Telematics, and LBS is confirmed.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.260-264
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• 2003

Among many factors to affect the network performance, this paper analyses how the buffer size of NIC(Network Interface Card) can affect web server and LAN(Local Area Network). We use the ns-2 which is defacto network simulation tool to observe the changes in drop rate, throughput, RTT(Round Trip Time), effective throughput depending on varying buffer sizes. And we analyse the effect of NIC buffer size on the web traffic in Ethernet.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.1
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• pp.26-33
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• 2013

Femto-cells are low power/cost, micro-base stations and are main components in heterogeneous networks. However, some of technical issues arise when femto-cells are initially installed. One approach to resolve the problems is to control the transmission (TX) power autonomously via SON(Self-Organized Network) scheme. By controlling the femto-cell TX power, the system throughput performance can be improved or the system overhead is highly reduced. Generally, the TX power for maximizing the system throughput and that for reduced system overhead may not be identical. Therefore, we propose a TX power control scheme by which we can improve the system throughput and reduce the system overhead, simultaneously. When we apply the proposed method, the simulation results show that the system overhead can be reduced by up to 41% compared to the performance of the method which maximizes throughput performance only, and the throughput performance can be improved by up to 63% compared to that of the method which only optimizes the coverage area.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.84-93
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• 2007

In this paper, a Radix-8 structure for high-speed FFT is propose. Main block of the proposed FFT structure is Radix-8 DIF(Decimation In Frequency) butterfly. Even throughput of the Radix-8 FFT is twice than that of the Radix-4 FFT, implementation area of the Radix-8 is larger than that of Radix-4 FFT. But, implementation area of the proposed Radix-8 FFT was reduced by using DA(Distributed Arithmetic) for multiplication. For comparison, the 64-point FFT was implemented using conventional Radix-4 butterfly and proposed Radix-8 butterfly, respectively. The Verilog-HDL coding results for the proposed FFT structure show 49.2% cell area increment comparison with those of the conventional Radix-4 FFT structure. Namely, to speed up twice, 49.2% of area cost is required. In case of same throughput, power consumption of the proposed structure is reduced by 25.4%. Due to its efficient processing scheme, the proposed FFT structure can be used in large size of FFT like OFDM Modem.

• 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.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.85-86
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• 2007

In this paper, a Radix-8 structure for high-speed FFT is proposed. Even throughput of the Radix-8 FFT is twice than that of the Radix-4 FFT, implementation area of the Radix-8 is larger than that of Radix-4 FFT. But, implementation area of the proposed Radix-8 FFT was reduced by using DA(Distributed Arithmetic) for multiplication. The Verilog-HDL coding results for the proposed FFT structure show 49.2% cell area increment comparison with those of the conventional Radix-4 FFT structure. Namely, to speed up twice, 49.2% of area cost is required. In case of same throughput, power consumption of the proposed structure is reduced by 25.4%.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.419-427
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• 2015

There have been increases in the elderly population worldwide, and this has been accompanied by rapid growth in the health-care market, as there is an ongoing need to monitor the health of individuals. Wireless body area networks (WBANs) consist of wireless sensors attached on or inside the human body to monitor vital health-related problems, e.g., electrocardiograms (ECGs), electroencephalograms (EEGs), and electronystagmograms (ENGs). With WBANs, patients' vital signs are recorded by each sensor and sent to a coordinator. However, because of obstructions by the human body, sensors cannot always send the data to the coordinator, requiring them to transmit at higher power. Therefore, we need to consider the lifetime of the sensors given their required transmit power. In the IEEE 802.15.6 standard, the transmission topology functions as a one-hop star plus one topology. In order to obtain a high throughput, we reduce the transmit power of the sensors and maintain equity for all sensors. We propose the multiple-hop transmission for WBANs based on the IEEE 802.15.6 carrier-sense multiple-access with collision avoidance (CSMA/CA) protocol. We calculate the throughput and variance of the transmit power by performing simulations, and we discuss the results obtained using the proposed theorems.

• Journal of Multimedia Information System
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• v.3 no.4
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• pp.149-154
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• 2016

Wireless mesh networks (WMNs) are used for metropolitan area network that requires high network throughput for handling many users. TDMA-based access is a common solution for this problem and several scheduling methods have been proposed. However, existing heuristic methods have room for improvement at network throughput although they are low complexity. In this paper, we propose a novel divided scheduling method based on structural characteristics in order to improve network throughput in WMNs. It separately schedules neighbor links of gateways and that of the other links by different scheduling algorithms. Simulation-based evaluations show that our proposal improves up to 14% of network throughput compared with conventional scheduling algorithm script.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.501-515
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• 2006

The IEEE 802.11 protocol is the most mature technology for WLANs(Wireless Local Area Networks). However, as the number of stations increases, the delay and throughput performance of IEEE 802.11 MAC(Medium Access Control) degrades severely. In this paper, we present the comprehensive performance analysis of IEEE 802.11 MAC protocol by investigating the MAC layer packet service time when arrival packet sizes have a general probability distribution. We obtain the discrete probability distribution of the MAC layer service time. By using this, we analyze the system throughput and the MAC layer packet service time of IEEE 802.11 MAC protocol in wireless LAN environment. We take some numerical examples for the system throughput and the mean packet service time for several special distributions of arrival packet sizes.