• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.215-220
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• 2009

LR-WPAN(Low-Rate Wireless Personal Area Network) hewn as IEEE 802.15.4 is considered as one of the most suitable specifications published until now to accomplish USN(Ubiquitous Sensor Network). In this paper we simulate interference effects to other systems if LR-WPAN will be used in 900MHz. In considering the current usage situation of 900MHz frequency band, we can think LR-WPAN shares the frequency band of $908.5{\sim}914MHz$ assigned for RFID/USN. The simulation results of the case of LR-WPAN and RFID/USN sharing the frequency band show that the probability of interference of LR-WPAN to CT1 and RFID is 2.5% and 2.1%, respectively. In order to avoid interference effects to public communications, simulations results show that the protection distance of about loom is needed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.310-317
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• 2008

Data collision in LR-WPAN(Low Rate Wireless Personal Area Network) causes retransmission of which energy consumption may reduce life of the entire network. Furthermore LR-WPAN is very sensitive to collision as it has relatively fewer frequencies of backoff retries. LCS(Limited Contention Scheme) suggested in this study is a way to transmit data by certain groups of the total nodes so that it can reduce possibilities of data collision and retransmission by decreasing the number of competing nodes. As a result LCS can increase a throughput and the life of the entire network. As using LCS in designing LR-WPAN in the future can extend battery life, LCS can be useful in any application that requires low energy consumption.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.178-180
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• 2005

저렴한 비용, 매우 작은 파워 소비라 낮은 데이터 전송속도를 지원 하는 IEEE 802.15.4 LR-WPAN(Wireless Personal Area Network) 기술은 앞으로 다가올 유비쿼터스 시대의 핵심이라고 할 수 있다. 도래할 유비쿼터스 시대에는 댁내에 LR-WPAN 기술을 적용한 다양한 상품이 보급될 것이다. 그러나 LR-WPAN은 매우 낮은 전력 소비를 위해 네트워크 기능을 최소화 하였기 때문에 응용에 있어 LAN 또는 WLAN(Wireless Local Area Network)등 기존 네트워크와의 통신 및 보안이 아직 고려되지 않아 보완이 필요하다. 본 논문에서는 WLAN의 Station이 LR-WPAN을 보안적으로 안전하게 제어할 수 있도록 AP(Acess Point)와 WLAN의 Station 그리고 LR-WPAN의 PAN Coodinator 간의 새로운 Message와 Function를 정의하고, 다른 두 네트워크간의 효율적이고 보안이 유지되는 프레임 프로세싱 매커니즘을 제안한다.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.5
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• pp.21-30
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• 2011

In this paper, we propose a real-time service based on retransmission slot in low rate WPAN. In the proposed scheme, during the communication period of the beacon-enabled mode in LR-WPAN standard, a special GTSs is dynamically assigned for retransmission of the packet that fails during a real-time service such as voice. This provides a time diversity in the severe channel error environments to support the required QoS. Analytical results show that this scheme achieves a much higher throughput and better transmission success rate per GTS slot than conventional schemes such as a common reserved scheme in LR WPAN.

• Journal of IKEEE
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• v.20 no.1
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• pp.107-110
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• 2016

In this paper, an IEEE 802.15.4 LR-WPAN 868/915 MHz ZigBee transceiver for IoT systems was designed and implemented. Non-coherent demodulation was exploited to satisfy ${\pm}80ppm$ frequency offset recommended in IEEE 802.15.4 LR-WPAN. Variable bitrate was supported according to operation modes. SPI module was embedded to connect various MCUs. The designed Zigbee transceiver was described in Verilog HDL and it was synthesized and verified in $0.18{\mu}m$ process. Its gate count was about 32,000 gates.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.1
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• pp.9-16
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• 2016

Since most of devices in the IEEE 802.15.4 LR-WPAN are expected to operate on batteries, they must be designed to consume energy in a very conservative way. Two energy conservation algorithms are proposed for the LR-WPAN: DDC (Dynamic Duty Cycle) and DBT (Dynamic Beacon Tracking). The DDC algorithm adjusts duty cycle dynamically depending on channel conditions. The DBT algorithm switches beacon tracking mode on and off adaptively depending on traffic conditions. Combining the two algorithms reduces energy consumption more efficiently for a wide range of input loads, while maintaining frame delivery ratio and average delay at satisfactory levels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.176-186
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• 2006

In this paper, we propose an enhanced symbol detector algorithm for 2.45GHz LR-WPAN(Low-Rate Wireless Personal Area Network) receiver. Because the frequency offset of $\pm$80ppm on 2.45GHz band is recommended in IEEE 802.15.4 LR-WPAN(Low-Rate Wireless Personal Area Network) specification, a symbol detector algorithm having stable operation in the channel environment with large frequency offset is required. For robustness to the frequency offset, non-coherent detection-based symbol detector algorithm is typically applied in the LR-WPAN receiver modem. However, the noncoherent symbol detector has increased performance degradation and hardware complexity due to squaring loss of I/Q squaring operation. Therefore we propose a coherent detection-based symbol detector algorithm with frequency offset compensation using a preamble symbol. The proposed algorithm is more suitable for LR-WPAN receiver aimed at low-cost, low-power and low-complexity than the non-coherent symbol detector, since it can reduce performance degradation due to squaring loss of I/Q squaring operation and implementation complexity. Simulation results show that the proposed algorithm has performance improvement of about 1dB in various channel environments.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.705-711
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• 2013

In this paper, we present a low-complexity non-coherent demodulation algorithm and hardware architecture for LR-WPAN systems which can support the variable data rate for various applications. The need for LR-WPAN systems that can support the variable data rate is increasing due to the emergence of various sensor applications. Since the existing symbol based double correlation (SBDC) algorithm requires the increase of complexity to support the variable data rate, we propose the sample based double correlation (SPDC) algorithm which can be implemented without the increase of complexity. The proposed non-coherent demodulator was designed by verilog HDL and implemented with FPGA prototype board.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.5
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• pp.33-41
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• 2009

In this paper, we propose a scheme for voice 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 voice streaming data can be transferred more easily. In this research, we study the beacon-enabled mode in IEEE 802.15.4 LR-WPAN standard with 250Kbps data rate. In the proposed scheme, special slots are dynamically assigned for retransmission of the packet that fails during a voice 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 the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.49-56
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• 2006

This paper describes the design and the verification of IEEE 802.15.4 LR-WPAN 2.4GHz Physical layer for Ubiquitous Sensor Network(USN). We designed the Carrier Frequency Offset(CFO) compensation satisfied the frequency tolerance of IEEE 802.15.4 LR-WPAN and the adaptive matched filter that re-setting of the threshold for the symbol synchronization of the various USN environment. The multiplications is reduced 1/16 by this method each other at i, q phases and has 0.5dB performance improvement in detection probability. Proposed baseband system is designed with verilog HDL and implemented using FPGA prototype board.