• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.43-52
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• 2010

In this paper, the mobile-WiMAX (m-WiMAX) using the Smart antenna technique is implemented. Experiments are performed to compare Smart antenna system with conventional single antenna system. To implement the m-WiMAX smart antenna system there are many considerations, key issues of which are symbol time acquisition, beamforming, calibration. In the paper, symbol time acquisition, beamforming, calibration are implemented in WiMAX Smart antenna system and we verified that Smart antenna system is superior to single antenna system. The experimental results show 5.5 dB performance enhancement of implemented Smart antenna system in throughput compared with a single antenna system. The experimental result is almost same as theoretical result of 6 dB.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.564-567
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• 2011

Preserving energy of sensor node in wireless sensor network is an effort to prolong the lifetime of network. Energy of sensor node is very crucial because battery powered and irreplaceable. Energy conservation of sensor node is an effort to reduce energy consumption in order to preserve resource for network lifetime. It can be achieved through efficient energy usage by reducing consumption of energy or decrease energy usage while achieving a similar outcome. In this paper, we propose optimization of energy efficient base station assisted hierarchical routing protocol in wireless sensor network, named BSAH, which use base station to controlled overhead of sensor node and create clustering to distribute energy dissipation and increase energy efficiency of all sensor node. Main idea of BSAH is based on the concept of BeamStar, which divide sensor node into group by base station uses directional antenna and maximize the computation energy in base station to reduce computational energy in sensor node for conservation of network lifetime. The performance of BSAH compared to PEGASIS and CHIRON based of hierarchical routing protocol. The simulation results show that BSAH achieve 25% and 30% of improvement on network lifetime.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.326-332
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• 2006

In this study, the antenna was proposed for the omni-directional characteristic in horizontal plane. Therefore we proposed $1{\times}4$ microstrip patch array on cylindrical surface for studying microstrip patch antennas. This antenna is designed for 2.45GHz ISM band and applications. This antenna can be applied to the base station of wireless microphone and access point of wireless LAN. The length and width of the patch antenna and the width of the feed line were calculated by using the theory of microstrip patch antenna, by using the both the 2.5D and 3D EM simulators the optimized antenna characteristics are obtained. From result of measured, antenna's impedance of coaxial waveguide port was 51.915-j3.688 ${\Omega}$, the return loss was -31dB and VSWR was 1.081.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.665-675
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• 2001

In this paper, the reverse link performance of a imperfect power controlled DS/CDMA cellular system that uses a base station array antenna which can effectively remove the multiple access interference is analyzed considering both beam forming algorithm and power control error in shadowing. The blocking probability of the DS/CDMA cellular system based on array parameters, $E_b/N_o$ and statistics of interference is derived, and then the system capacity corresponding to a certain blocking probability is calculated. On the assumption that the blocking probability is set 1%, the system capacity using MCGM algorithm with 12 antenna arrays is more increased maximum 32 times than that using a omni-directional antenna and about 2 times than that using MMSE algorithm, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.433-436
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• 2013

Massive MIMO communication system with huge antennas has been attracting intensive attention as one of key technologies to increase the spectral efficiency. Many previous studies investigated single user Massive MIMO scheme in cellular downlink. Recently, however, intensive researches on multiuser-based Massive MIMO are performed to overcome the problem caused by the limited number of antennas in mobile stations. Although the Massive MIMO scheme based on huge number of antennas inevitably causes hardware and computational complexity in baseband and radio frequency (RF) elements, the problem can be mitigated without serious performance degradation by limiting the number of baseband and RF elements below the number of transmit antennas of base station and opportunistically selecting transmit antennas according to channel states, where the number of selected antennas corresponds to the number of baseband and RF elements in base station. Accordingly, this paper proposes a simple antenna selection scheme for multiuser-based Massive MIMO systems. Our simulation results indicate that the proposed antenna selection scheme can achieve comparable performance to the conventional scheme without antenna selection.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.632-636
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• 2006

It is needed to use the beam scanning to control the cell coverage of the base station considering operation conditions, season, time period, radiation character and mobility of customers and vehicles for varied wireless communication service and quality improvement. This paper proposes a mobile antenna system which can obtain the characteristics of the beam scanning by controlling the directivity depending on the operation condition. Radiation block is made of 2 sub-array of $1\times3$ patched antennas for ITS of 5.8GHZ bandwidth with the gain of 13dBi, and of 2 sub-array of single patched antenna for WiBro of 2.3GHZ bandwidth with the gain of 12dBi. RF module is made of a switch, an amplifier, a PAD, a 3-Bit phase shifter, and a power divider. The system is able to control the beam tilting with electronic methode by using 3-bit phase shifter$(45^{\circ},\;90^{\circ},\;180^{\circ})$.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.7-11
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• 2004

In this paper, the wideband microstrip patch antennas for the Personal communications Service (PCS : 1750∼1870 MHz) and International Mobile Telecommunications-2000 (IMT-2000 : 1920∼2170 MHz) dual band are studied. Experimental and simulation results on the dual band antenna are presented. Simulation results are in good agreement with measurements. The experimental and simulation results confirm the wideband characteristics of the antenna. The studied antenna satisfied the wideband characteristics that are required characteristics for above 420 MHz impedance bandwidth for the PCS and IMT-2000 dual band antenna. In this paper, through the designing of a dual band antenna, we have presented the availability for PCS ＆ IMT-2000 base station antenna. An impedance bandwidth of 33% (VSWR<1.5, 650 GHz) and a maximum gain of 7dB can be achieved. The radiation pattern is stable across the passband.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.149-152
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• 2000

In this paper, the reverse link performance of an imperfect power controlled DS/CDMA cellular system that uses a base station array antenna which can effectively remove the multiple access interference is analyzed considering both beam forming algorithm and power control error in shadowing. The blocking probability of the DS/CDMA cellular system based on array parameters, Eb/No and statistics of interference is derived, and then the system capacity corresponding to a certain blocking probability is calculated. On the assumption that the blocking probability is set 1 ％, the system capacity using MCGM algorithm with 12 antenna arrays is increased about 59 % than that using 8 antenna arrays when power control error is 2.5 ㏈.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.391-395
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• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we present a feasibility study on coaxial feed compact wideband antenna for UHF RFID reader application. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi$\sim$3.18 dBi at 910MHz.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.164-168
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• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we presents a feasibility study on single feed compact wideband antenna for wireless communication applications including GSM (890-960 MHz), GPS (1575 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2200 MHz), ISM (2400-2480 MHz), IMT2000 and satellite DMB bands. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi${\sim}$3.18 dBi at 1710 MHz${\sim}$1880 MHz.