• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.357-364
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• 2015

In this paper, we designed and implemented a PIFA(Planar Inverted F Antenna) + IFA(Inverted F Antenna) hybrid MIMO(Multi Input Multi Output) antenna for the hexa mobile communication service band. By the simultaneous operation both PIFA and IFA using the coupled feeding structure, we tried for application to modern mobile phones that have large ground size. A PIFA is applied to the ground area, and an IFA is applied to no ground small space on top of the phone. A diagonal fed MIMO antenna is implemented PCB embedded type without antenna carrier component. Implemented antenna on the bare board measured within 3 : 1 for VSWR under hexa mobile communication band as CDMA, GSM900, DCS, KPCS, USPCS, and WCDMA. Measured average gains and efficiencies were -5.19~-3.16 dBi and 30.27~48.26 % for the CDMA, GSM900 band, and -9.50~-5.19 dBi and 11.23~30.28 % for the DCS, KPCS, USPCS, WCDMA band. It's shown that studied antenna can be applied to the antenna for the modern mobile phone.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1066-1072
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• 2001

ALOHA Multi-Carrier DS-CDMA systems in the multipath Rayleigh fading channel. The throughput of two systems are compared according to the length of a packet in the fast Rayleigh and the slow Rayleigh multipath fading. As a result, we have known that Multi-Carrier DS-CDMA system has less capacity than wideband DS-CDMA system in the same bandwidth, but throughput of Multi-Carrier DS-CDMA system is higher than that of wideband DS-CDMA system. And in Multi-Carrier DS-CDMA systems, higher throughput can be obtained through shortening the length of packet in the fast Rayleigh fading, and it is efficient to control the length of a packet adequately or increase the system capacity of Multi-Carrier DS-CDMA system in the slow Rayleigh fading.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.817-823
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• 2010

Design of IPI feeding structure affecting the antenna gain improvement of mobile phone was investigated. IPI feeder which based on the T matching theory increase line current for internal antenna such as IFA. So IPI feeder makes higher radiation resistance, and also increases the gain with increasing radiation efficiency. To verify IPI feeding effect, feeder is applied to conventional CDMA/DCS dual band IFA. Measurement shows that IPI-IFA has 0.5 ~ 1.4[dBi] higher gain than conventional IFA at CDMA/DCS band. Resonant frequency did not change.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.359-369
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• 2005

For large capacity optical CDMA networks, we propose a shared-type encoder/decoders based on an tunable wavelength converter(TWC) and an arrayed waveguide grating (AWG) router. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.527-535
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• 2003

In this paper, the performance of W-CDMA system with smart antenna is analyzed for angular spread in realistic wideband multipath channel. The realistic wideband channel is assumed, one of which is JTC channel model. And each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. Several multipaths within one chip are distinguished into each one and the strongest signal is selected. As a result, the performance of the W-CDMA system with smart antenna in realistic wideband multipath channel has been considerably improved in proportion to the increase of angular spread.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.11-17
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• 2009

This paper deals with the estimation performance DoA (Direction of Arrival) using the 3D adaptive array antenna in W-CDMA signal. For this, we proposed the 5 types of 3D array antenna, and appied for the MUSIC in order to the estimation of DoA algorithm for that antenna, commonly, then the DoA estimation error was used for the estimation performance. In the mobile communication and radio positioning service, performing the spatial filtering after the DoA estimation in array antenna, the quality of receiving signal can improve by the nulling or minimization of interfering signal which is from the undesired direction and the forming of beam which is from the desired direction. The result of DoA estimation and the DoA estimation error by varying the signal to noise ration and the number of interfering signal and power of each type antenna was calculated by computer simulation. As a result of simulation, the other propose antenna has good performance excluding the stack 3D antenna in DoA estimation and the Curved-B type antenna has more superior performance when increasing the number of interfering signal and power in the DoA estimation error.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.55-59
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• 2014

Multi-band and multi-mode transmitters are needed for SDR and CR. Recently many types of polar transmitters have been studied in order to implement a multi-band and multi-mode transmitter. Polar transmitters have many advantages, such as a simple structure, high efficiency and etc. In this paper we consider the number of D/A bit and the effects of a delay mismatch as design parameters for implementing polar transmitters. From the simulation we know that a 10 bit D/A is sufficient and a delay mismatch must be maintained small than 1/64 chip for satisfying the spectrum mask characteristics. We implement a polar transmitter based on the design parameters and the measured output signal meet the spectrum mask of 800MHz CDMA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.248-256
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• 2015

In this paper, a hybrid MIMO antenna for the metal phone with auxiliary slot for 4th generation mobile communication is designed and implemented. Auxiliary slot locates on the rear metal cover of the phone, and handles for LTE class 40 band. The auxiliary slot operates hybrid with a monopole antenna. Studied antenna satisfies under VSWR 3:1 for LTE class 13/ LTE class 14/ CDMA/ GSM/ DCS/ PCS/ W-CDMA/ LTE class 40 bands. ECC(Envelope Correlation Coefficient) value for MIMO characteristic is less than 0.2 over the whole design bands. Average gains and antenna efficiencies measured by MTG anechoic chamber were -5.57~-1.45 dBi and 27.75~71.6 %, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.395-398
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• 2016

In this paper, a hybrid MIMO antenna for the mobile communication metal phone with auxiliary letter slot is designed and implemented. Auxiliary letter slot locates on the rear metal cover of the phone, and operates on LTE class 40 band. The slots of two letters are designed and operated with monopole+IFA hybrid antenna. Antenna satisfies under VSWR 3: 1 for LTE class 13 / LTE class 14 / CDMA / GSM / DCS / PCS / W-CDMA / LTE class 40 bands. Average gains and antenna efficiencies measured by the anechoic chamber were -5.57~-1.45 dBi and 27.75~71.6 %, respectively.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.143-148
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• 2003

In this paper, we focused on the performance of reverse link in 1.8GHz CDMA 1x system including the Tower-Mount LNA in an urban environment. In order to study the benefit of TMLNA, Hata model is used and the effects of multiple cells are considered. Cell coverage extension ratio is proportional to the increased gain of TMLNA in CDMA cell site. However the cell coverage is not extended even if the noise figure of TMLNA is reduced in an urban area. When typical RSSI is between -70dBm and -80dBm, the increased gain and the reduced NF of TMLNA are not impact to the pole capacity of cell site. Namely, the benefit of TMLNA in an urban area is not the problem of capacity but the proble of sensitivity. The results are also shown that reverse link $E_b/N_o$ is improved by minimum 5dB and BER is lower than $10^{-6}$.