• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.838-839
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• 2016

IEEE 802.15.4 is the standard wireless link technology for low power, low cost, but long lifetime applications including wireless sensor network (WSN). Currently, whether or not IP architecture should be used in WSN over its 802.15.4 link is under dispute. Such kind of arguments may last for a long time without some convincing experimental measurements of real case performances of IP over 802.15.4 implementation, and thus prevent the advance of related research. In RFC4944, IETF proposed the 6LoWPAN specification to enable IPv6 communication over low power, wireless personal area networks. We try to alleviate the dispute and make the direction clearer to the community so as to promote further valuable research in this topic.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.4
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• pp.29-38
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• 2005

Because IEEE 802.11 has several security vulnerabilities, IEEE 802.11i was proposed and accepted. But IEEE 802.11i has much overhead for most of users for the web surfing. Besides not only node the authentication but also the packet authentication is needed to communicate. Although IEEE 802.11i uses TKIP(Temporal Key integrity Protocol) and CCMP(CTR with CBC-MAC Protocol), they have a lot of overheads. In this paper, Lightweight Packet Authentication(LIPA) is proposed. LIPA has less overhead and short delay so that it can be affordable for simple web-surfing which does not need stronger security. After comparing performances of LIPA with those of TKIP and CCMP, LIPA is more efficient than other schemes for transmitting packets.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.82-94
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• 2007

Wireless sensor networking technology is one of the basic infrastructures for ubiquitous environment. It enables us to gather various sensory data such as temperature, humidity, gas leakage, and speed from the remote sensor devices. To support these networking functions, IEEE WPAN working group makes standards for PHY and MAC, while ZigBee Alliance defines the standards for the network, security, and applications. The low-rate WPAN was emerged to have the characteristics of network resilience, low cost, and low power consumption. It has a broad range of applications including, but not limit to industrial control and monitoring, home automation, disaster forecast and monitoring, health care. In order to provide more intelligent and robust services, users want voice-based solutions to accommodate to low-rate WPAN. In this paper, we have evaluated voice quality of an IEEE 802.15.4 standard compliant voice node. Specifically, it includes the design of a voice node and experiments based on the prediction of voice quality using the E-model suggested by ITU-T G.107, and the network communication mechanisms considering beacon-enabled and nonbeacon-enabled networks for real-time voice communications.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.216-219
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• 2003

In this paper, we present performance analysis of an IEEE P802.15.3a high rate wireless personal area network transceiver. This physical layer standard uses QOSK as its sub-channel modulation scheme and orthogonal frequency domain modulation (OFDM) for sub-bands. OFDM is used for each sub-band so that multi-path effects are absorbed by equalizer and guard, and fading can be approximately modeled as additive white Gaussian noise. In multi-band ultra-wideband system, DAC quantization error is important noise source since high resolution conversion cannot be used due to high power consumption. Simulation result shows that, to get 640-Mbps throughput, at least 5-bits precision is necessary to maintain bit-error rate under 10$\^$-2/, which can be lowered, with channel coding, to 10$\^$-6/ that is the bit-error rate required by IEEE 802.15 upper protocol layer, in 4-meter LOS fading channel.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.109-116
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• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1A
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• pp.74-84
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• 2008

UWB radio systems have drawn attention during the last few years. These systems are the core technique for ubiquitous home and enable to co-exist with other narrow band systems over the same frequency without interfering them. But UWB signals have a very low power per pulse, so they are affected by strong narrow band interferences. Specially, IEEE 802.11a systems which operate around 5GHz overlap the band of UWB signals and they will interfere with UWB systems significantly. In this paper, we propose a novel narrow band interference suppression method based on singular value decomposition(SVD) algorithm for DS-UWB in IEEE 802.15.4a channel model. The proposed method is very effective and robust for both a single user DS-UWB system and a multiuser DS-UWB system to reduce the narrow band interference.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.835-844
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• 2008

ZigBee devices are limited in resources especially on power and computational capacity but also require real-time operation at MAC layer. Therefore, it is important to take those requirement into consideration of system software design. In this paper, we proposed a compact system software design to support simultaneously ZigBee and IEEE802.15.4. The design strictly respects the resource and real-time constraints while being optimized for specific functions of both Zigbee and IEEE802.15.4. Various evaluations are done to show significant metrics of our design.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.19-27
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• 2010

In this paper, we propose a scheme for real-time data retransmission in LR-WPAN to support the required QoS even in the severe channel error environments. In IEEE 802.15.4a, as the user data rate is supported up to 850Kbps, the real-time streaming data can be transferred more easily. In this research, we study the beacon-enabled mode in IEEE 802.15.4 LR-WPAN standard. In the proposed scheme, special slots are dynamical1y assigned for retransmission of the packet that fails during a real-time data service, and in the severe channel error environments a time diversity is acquired. Analytical results show that the proposed scheme is more robust and achieves a much higher throughput than the previous protocol in LR-WPAN.

• Journal of KIISE
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• v.44 no.2
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• pp.213-222
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• 2017

The Internet of Things (IoT) technology is rapidly developing in recent years, and is applicable to various fields. A smart factory is one wherein all the components are organically connected to each other via a WSN, using an intelligent operating system and the IoT. A smart factory technology is used for flexible process automation and custom manufacturing, and hence needs adaptive network management for frequent network fluctuations. Moreover, ensuring the timeliness of the data collected through sensor nodes is crucial. In order to ensure network timeliness, the power consumption for information exchange increases. In this paper, we propose an IEEE 802.15.4e DSME-based distributed scheduling algorithm for mobility support, and we evaluate various performance metrics. The proposed algorithm adaptively assigns communication slots by analyzing the network traffic of each node, and improves the network reliability and timeliness. The experimental results indicate that the throughput of the DSME MAC protocol is better than the IEEE 802.15.4e TSCH and the legacy slotted CSMA/CA in large networks with more than 30 nodes. Also, the proposed algorithm improves the throughput by 15%, higher than other MACs including the original DSME. Experimentally, we confirm that the algorithm reduces power consumption by improving the availability of communication slots. The proposed algorithm improves the power consumption by 40%, higher than other MACs.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.295-309
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• 2015

Beacon scheduling is considered to be one of the most significant challenges for energy-efficient Low-Rate Wireless Personal Area Network (LR-WPAN) multi-hop networks. The emerging new standard, IEEE802.15.4e, contains a distributed beacon scheduling functionality that utilizes a specific bitmap and multi-superframe structure. However, this new standard does not provide a critical recipe for superframe duration (SD) allocation in beacon scheduling. Therefore, in this paper, we first introduce three different SD allocation approaches, LSB first, MSB first, and random. Via experiments we show that IEEE802.15.4e DSME beacon scheduling performs differently for different SD allocation schemes. Based on our experimental results we propose an adaptive SD allocation (ASDA) algorithm. It utilizes a single indicator, a distributed neighboring slot incrementer (DNSI). The experimental results demonstrate that the ASDA has a superior performance over other methods from the viewpoint of resource efficiency.