• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.677-687
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• 2008

CR technology is an intelligent technology which can sense the spectrum environment an adaptively adjust the parameters for wireless transmission. In this paper, by using CR-UWB, the spectrum efficiency of the transmission channel is largely improved; Furthermore, the interference to other system can be effectively avoided. In this paper, we propose a solution on interference problem of UWB system using cognitive radio. We use interference temperature model of cognitive radio that has proposed by FCC for estimating interference signal. Calculating channel capacity of UWB system with interference temperature, we suggest how to solve interference problem. We have used genetic algorithm in cognitive engine's calculation precess. The proposed UWB System with cognitive radio shows very efficient in solving interference problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.742-753
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• 2005

In this paper, we propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in typical indoor wireless channels. The proposed scheme is a two-step search with different thresholds and search window applied to a single correlator, where each step utilizes the single-dwell search with the bit reversal. Simulation results in IEEE 802. I5 Task Group .3a UWB indoor wireless channel show that the proposed scheme for the LHWB signals can achieve significant reduction of the required mean acquisition time as compared to the conventional single-dwell bit reversal search and double-dwell bit reversal search with more complex structure employing two correlators for various threshold levels. In addition, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition in noisy environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.215-220
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• 2016

In this paper, a wideband antenna accomplished by adding a double sleeve of a rectangular planar monopole structure is proposed. In order to impedance matching of proposed antenna, the antenna performance was improved by adding two gap sleeves and outer sleeve for double sleeve structure. HFSS simulator of ANSYS corp. was used in order to confirm the antenna parameter characteristic. According to the simulation results, the VSWR was less than 2 for the range of 2.5GHz~10.5GHz. The frequency bandwidth is 8GHz. The frequency range of the actual fabricated antenna was 2.92GHz~10.32GHz, the frequency bandwidth is 7.4GHz. The measured radiation pattern frequency is 3GHz, 6GHz and 9GHz. The results are similar with dipole antenna pattern in all frequency. The antenna size is $40{\times}40mm^2$. The utilization possibility of the ultra-wideband planar monopole antenna could be confirmed according to compare and analyze the simulation and measurement data.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.317-324
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• 2016

WiMedia provides the data rate of up to 1Gbps, but the transmission range is restricted to approximately 10 meters. When constructing a multi-hop WiMedia network to extend its coverage, conventional hop-based routing may not guarantee satisfactorily the required QoS. We propose two QoS routing techniques for the WiMedia-based wireless mesh network. The proopsed QoS routing reflects the characteristics of TDMA-based WiMedia MAC and develops QoS extensions separately for on-demand routing and table-driven routing. Through simulations, we identify that the QoS routing shows better performance than the hop-based routing. It also turns out that the QoS on-demand routing and the QoS table-driven routing show conflicting performance results depending on the transmission power.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.811-817
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• 2014

In this paper, a design method for a dual-band monopole antenna operating in the bands of 2.45 GHz WLAN and UWB is studied. A monopole antenna operating in UWB band is first designed, and a slot is inserted on the monopole to operate in 2.45 GHz WLAN band. The optimized dual-band monopole antenna is fabricated on an FR4 substrate, and the experimental results show that the antenna has a dual-band characterisitc in WLAN and UWB bands with the frequency bands of 2.35-2.50 GHz and 2.99-11.82 GHz for a VSWR < 2. Measured gain is 1 dBi at 2.45 GHz, and ranges 1.5-4.6 dBi in the frequency band of 3.1-10.6 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.9-15
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• 2006

In this paper, signal processing techniques for noncoherent impulse-radio-based UWB (IR-UWB) communication system are proposed to provide system implementation of low power consumption and low complexity. The proposed system adopts a simple modulation technique of OOK (on-oft-keying) and noncoherent signal detection based on signal amplitude. In particular, a technique of a novel high speed digital sampler using a stable, lower reference clock is developed to detect nano-second pulses and recover digital signals from the pulses. Also, a 32 bits Turyn code for data frame synchronization and a convolution code as FEC are applied, respectively. To verify the proposed signal processing techniques for low power, low complexity noncoherent IR-UWB system, the proposed signal processing technique is implemented in FPGA and then a short-range communication system for wireless transmission of high quality MP3 data is designed and tested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1623-1632
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• 2004

In this paper, we analyze the performance of linear search and bit reversal search algorithms based on the single-dwell serial search for rapid UWB (Ultra Wide Band) signal acquisition in typical indoor wireless channel environments. Simulation results according to bin spacing and frame interval in IEEE 802.15 Task Group 3a UWB indoor wireless channels show that bit reversal search algorithm achieves much smaller normalized mean acquisition time than linear search algorithm. In particular, it is found that the normalized mean acquisition time of the bit reversal search according to the range of searching termination interval closely matches the ideal case. In addition, we observe that the acquisition performance of bit reversal search algorithm becomes much better as bin spacing gets finer.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.74-79
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• 2008

CR technology is an intelligent technology which can sense the spectrum environment an adaptively adjust the parameters for wireless transmission. In this paper, by using CR-UWB, the spectrum efficiency of the transmission channel is largely improved; Furthermore, the interference to other system can be effectively avoided. In this paper, we propose a solution on interference problem of UWB system using cognitive radio. We use interference temperature model of cognitive radio that has proposed by FCC for estimating interference signal. Calculating channel capacity of UWB system with interference temperature, we suggest how to solve interference problem. We have used genetic algorithm in cognitive engine's calculation precess. The proposed UWB System with cognitive radio shows very efficient in solving interference problem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1255-1260
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• 2009

Microstrip interdigital filter is designed with the width and length of a resonator, the gap distance between resonators and the location of a tap. When designing filters, it is a benefit to design with few design parameters comparing to many design parameters. In this paper we design and implement two microstrip interdigital filters operating in the UWB(Ultra Wide-Band) frequency band, one using a fixed width of a resonator and the other using a different width of resonators. The test results of the implemented filters show that the low-band high filter with a fixed width has the insertion loss of 1.49dB, -10dB band width of 720MHz, -35.7dBattenuation at 4.8GHzand below -13dB of S11. The filter with a different width of resonators has the insertion loss of 1.6dB, -10dBbandwidth of 1.63GHz and below-8dBof S11.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.387-392
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• 2022

In addition to complying with access standards for facilities that require infection control (operating rooms, delivery rooms, intensive care units, etc.) in accordance with the 2019 Medical Care Act Enforcement Regulations, entry, exit, contact information, etc. for entry and exit, the criteria for entering and exiting special rooms of medical institutions have been revised so that records of facts are kept for one year. However, even now, the inconvenience continues due to the fact that such contents are created by hand or due to errors. For this reason, this study designed and implemented a system that provides automatic opening, closing, and accessing record storage functions for authorized users using IoT devices and UWB technology, and we expected that the convenience of the visitors and systemized access control will be possible.