• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.389-395
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• 2013

Ethernet is the most widely deployed access network protocol around the world. IEEE 802.3az WG released the EEE standard based on LPI mode to improve the energy efficiency of Ethernet. This paper proposes improved adaptive power control mechanism that can enhance energy-efficiency based on EEE from small Ethernet switch. The feature of this mechanism is that it predicts the traffic characteristic of next cycle by measuring the amount of traffic flowing in during certain period and adjusts the optimal threshold value to relevant traffic load. Performance evaluation results indicate that the proposed mechanism improves overall performance compared to traditional mechanism, since it significantly reduces energy consumption rate, even though average packet delay increases a little bit.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.983-989
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• 2012

IEEE 802.3az LPI mechanism allows an Ethernet link to reduce power consumption by entering a low-power sleeping mode and letting some components being powered off when there is no data to be transmitted through the link. However, if small amount of packets are being sent periodically, such a mechanism can not obtain energy efficiency due to a high overhead caused by excessive mode transitions. In this paper, we propose an enhanced LPI mechanism which can perform state transition adaptively based on the traffic characteristics on transport layer and network status. This simulation result shows that proposed mechanism improves energy efficiency than LPI mechanism with respect to energy consumption rate for various traffic loads.

• Journal of Internet Computing and Services
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• v.11 no.3
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• pp.43-51
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• 2010

In this paper, we evaluate the system throughput and the method of optimal wireless resource allocation for the access zone (AZ) and relay zone (RZ) in downlink when the cell coverage is extended using the non-transparent Relay Station (RS) in a 2-hop cellular relay system based on IEEE802.16j, which uses the OFDMA-TDD structure. For the analyses, we first introduce the MAC (Media Access Control) frame structure in the non-transparent mode, then we investigate the interfering elements in both AZ and RZ for the network devices such as the Mobile Station (MS) and RS. Through computer simulation, we analyze the cell coverage extension and system throughput in terms of the distance between Base Station (BS) and RS, then we present the amount of the optimal allocation of wireless resource for the AZ and RZ in downlink using our results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.119-133
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• 2009

The purpose of this research is to accurately estimate the location of a device using the received signal strength indicator (RSSI) of IEEE 802.11 WLAN for location tracking in indoor environments. For the location estimation method, we adopted the calibration model. By applying the Adaptive Zone Based K-NNSS (AZ-NNSS) algorithm, which considers the velocity of devices, this paper presents a 9% improvement of accuracy compared to the existing K-NNSS-based research, with 37% of the K-NNSS computation load. The accuracy is further enhanced by using a Kalman filter; the improvement was about 24%. This research also shows the level of accuracy that can be achieved by replacing a subset of the calibration data with values computed by a numerical equation, and suggests a reasonable number of calibration points. In addition, we use both the mean error distance (MED) and hit ratio to evaluate the accuracy of location estimation, while avoiding a biased comparison.

• Journal of Information Technology Services
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• v.14 no.3
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• pp.183-196
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• 2015

The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. A common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. The IEEE 802.3az Energy Efficient Ethernet (EEE) standard is one of such efforts. EEE introduces a low power mode for the most common Ethernet physical layer standards and is expected to provide large energy savings. However, it has been shown that EEE may not achieve good energy efficiency because mode transition overheads can be significant, leading to almost full energy consumption even at low utilization levels. Coalescing techniques such as packet coalescing and interrupt coalescing were proposed to improve energy efficiency of EEE, but their implementations typically adopt a simple policy that employs a few fixed values for coalescing parameters, thus it is difficult to achieve optimal energy efficiency. The paper proposes adaptive interrupt coalescing (AIC) that adopts an optimal policy that could not only improve energy efficiency but support performance. AIC has been implemented at the sender side with the Intel 82579 network interface card (NIC) and e1000e Linux device driver. The experiments were performed at 100 M bps transfer rate and show that energy efficiency of AIC is improved in most cases despite performance consideration and in the best case can be improved up to 37% compared to that of conventional interrupt coalescing techniques.