• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.11-19
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• 2010

ZigBee is a standard for wireless personal area networks(WPANs) based on the IEEE 802.15.4 standard. It has been developed for low cost and low power consumption. There are two alternative routing schemes that have been proposed for the ZigBee standard: Ad-hoc On-Demand Distance Vector(AODV) and tree routing. The tree routing forwards packets from sensors to a sink node based on the parent-child relationships established by the IEEE 802.15.4 MAC topology formation procedure. In order to join the network, a sensor node chooses an existing node with the strongest RSSI(Received signal strength indicator) signal as a parent node. Therefore, some nodes carry a large amount of traffic load and exhaust their energy rapidly. To overcome this problem, we introduce a new metric based on link quality and traffic load for load balancing. Instead of the strength of RSSI, the proposed scheme uses the new metric to choose a parent node during the topology formation procedure. Extensive simulation results using TOSSIM(TinyOS mote SIMulator) show that the CFR scheme outperforms well in comparison to the conventional tree routing scheme.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.87-91
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• 2006

With the growth of the internet, the number of wireless internet users has increased continuously up to date. However, mobile communications could not support high speed transmission rate with cheap communication fee and wireless LAN has problems in providing terminal mobility and wide area connectivity, respectively. So the WMAN standard has been newly designed to make up for these limits. The initial 802.16 specification effectively offers a solution for providing fixed users with high speed wireless communication but it does not offer terminal mobility. So the 802.16d and 802.16e have been developed as the next generation solution that can support various PHY layer (SC, SCa, OFDM, OFDMA) and offer the terminal mobility. In this paper, we propose an effective uplink scheduling algorithm for VoIP with using UGS, and we show that our proposed algorithm is superior in view of average delay and management of uplink bandwidth to conventional rtPS algorithm and the scheme in reference, with using NS-2 network simulator.

• Journal of the Korea Computer Industry Society
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• v.10 no.5
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• pp.193-200
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• 2009

In this paper, the raid and fire preventable system using Zibee module with IEEE 802.15.4 wireless communication standard and multi-sensor was developed displaying raid and firing condition with wireless network. The raid preventable system is designed using a ultrasonhe waves sensor and infrared sensor. The fire preventable system is designed using a thermistor. The datas for raid and firing condition are communicated from enddevice to coordinator with wireless network and are displayed on PC monitor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.575-578
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• 2004

At the present and future, the connecting net of the form to integrate the wireless with the wire have been constructed in various field, while the use of the wireless communication is increased. In the paper, We proposed and considered the standard proposal of this Zigbee(IEEE 802.15.4) which is the low price, speed and power wireless communication field and to foundation about Wireless Home Safety Supervisor System.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.344-346
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• 2019

In this paper, we propose a distance estimation method using the convolutional neural network in Ultra-Wideband (UWB) systems. The training data set used to learn the deep learning model using the convolutional neural network is generated by the MATLAB program and utilizes the IEEE 802.15.4a standard. The performance of the proposed distance estimation method is verified by comparing the threshold based distance estimation technique and the performance comparison used in the conventional distance estimation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.685-690
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• 2013

This paper has proposed a multi-channel and wide gain-range baseband circuit blocks for the IEEE 802.15.4g MR-OFDM SUN systems. The proposed baseband circuit blocks consist of two negative-feedback VGAs, an active-RC 5th-order chebyshev low-pass-filter, and a DC-offset cancellation circuit. The proposed baseband circuit blocks provide 1 dB cut-off frequencies of 100 kHz, 200 kHz, 400 kHz, and 600 kHz respectively, and achieve a wide gain-range of +7 dB~+84 dB with 1 dB step. In addition, a DC-offset cancellation circuit has been adopted to mitigate DC-offset problems in direct-conversion receiver. Simulation results show a maximum input differential voltage of $1.5V_{pp}$ and noise figure of 42 dB and 37.6 dB at 5 kHz and 500 kHz, respectively. The proposed I-and Q-path baseband circuits have been implemented in $0.18-{\mu}m$ CMOS technology and consume 17 mW from a 1.8 V supply voltage.

• The Journal of Society for e-Business Studies
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• v.15 no.4
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• pp.49-58
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• 2010

The wireless sensor network technology becomes one of core technologies to make it possible to implement various e-business applications. Energy efficiency is an important issue in wireless sensor networks. IEEE 802.15.4, a representative international standard for wireless sensor networks, provides the beacon enabled mode for energy-efficient communication. However, the beacons may conflict each other when the network is of multi-hop topology such as mesh or cluster-tree topology with beacon-enabled mode. The beacon conflict causes the failure of synchronization between sensor nodes, and affects other nodes in the network in that unsynchronized nodes cannot participate in communication. In this paper, we suggest an energy-efficient beacon scheduling for the wireless sensor networks. Nodes can save their energy duringperiod and prevent beacon conflict using beacon scheduling. We implement the scheduling using QualNet, and evaluate the performance under mesh topology networks. It turns out that the proposed scheduling may improve the energy efficiency in the networks.

• Journal of Computing Science and Engineering
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• v.9 no.2
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• pp.83-97
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• 2015

IEEE 802.15.4 is a global standard designed for emerging applications in low-rate wireless personal area networks (LR-WPANs). The standard provides beneficial features, such as a beacon-enabled mode and guaranteed time slots for realtime data delivery. However, how to optimally operate those features is still an open issue. For the optimal operation of the features, this paper proposes a holistic optimization method that jointly optimizes three cross-related problems: cluster-tree construction, nodes' power configuration, and duty-cycle scheduling. Our holistic optimization method provides a solution for those problems so that all the real-time packets can be delivered within their deadlines in the most energy-efficient way. Our simulation study shows that compared to existing methods, our holistic optimization can guarantee the on-time delivery of all real-time packets while significantly saving energy, consequently, significantly increasing the lifetime of the network. Furthermore, we show that our holistic optimization can be extended to take advantage of the spatial reuse of a radio frequency resource among long distance nodes and, hence, significantly increase the entire network capacity.

• Journal of Information Technology Services
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• v.9 no.2
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• pp.151-161
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• 2010

Recently, as the era of ubiquitous has arrived, an infrastructure for the short-distance wireless communication has been extended socially, and thus a variety of services are being proposed. The Multimedia Contents Delivery System using the ZigBee, in particular, has an important stance in enlargement of a variety of services in the aspect of individual-oriented service support though Wireless Personal Area Network (WPAN). Nonetheless, the ZigBee, or the IEEE 802.15.4 Standard, has many restrictions on the Multimedia Contents Delivery System due to the low data transport rate. In order to improve the ZigBee which presents a limit on the transport rate at the IEEE 802.15.4 Standard, this thesis has designed the burst mode which is a method of transmitting a certain amount of data in block units at a high speed without any stoppage until the completion of the transmission. Also, to provide a Multimedia Contents Delivery Service with an application of the normal data transmission mode, it improved the transmission performance of the ZigBee. In addition, for the Multimedia Contents Delivery Service under the ubiquitous environment, it designed and implemented a broadcasting Multimedia Contents Delivery System based on the ZigBee to conduct a comparative analysis on the data transmission performance according to the transmission method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8A
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• pp.575-582
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• 2009

The localization algorithm(LAtu) using the IDentification Code($C_{ID}$) is suggested in RSS(Received Signal Strength) based Wireless Sensor Network(WSN), and the localization system using the suggested algorithm is designed and implemented in this paper. In addition to this, the performance of ranging correction quality and localization error of the localization system(System(LAtu)) that is developed using the LAtu is analyzed and compared with that of the localization system(System(LAieee)) using the channel model of IEEE 802.15.4 standard(LAieee) by the actual experimentation. From the experimentation, the ranging correction quality is analyzed that the LAtu is highly better than the channel model of LAieee about 34% under the distance between the moving module and the beacon module($D_{MM-BM}$) is 2m, and is also a few better than that of the LAieee about average 5% under the $D_{MM-BM}$ is above 5m. The localization error quality of the System(LAtu) is lower than that of the System(LAieee)) about 1cm under the lecture room and 4cm in the large lecture room.