• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.155-158
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• 2010

In this article, we proposed a new interference canceller using the adaptive algorithm. We designed constant modulus algorithm-correlation normailized least mean square (CMA-CNLMS) for wireless system. This structure is normalized LMS algorithm using correlation between the desired and input signal for cancelling the interference signals in the wideband code division multiple access (WCDMA) system. We showed that the proposed algorithm could improve the Mean Square Error (MSE) performance of LMS algorithm. MATLAB (Matrix Laboratory) is employed to analyze the proposed algorithm and to compare it with the experimental results. The MSE value of the LMS with mu=0.0001 was measured as - 12.5 dB, and that of the proposed algorithm was -19.5 dB which showed an improvement of 7dB.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.240-245
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• 2014

How well the self-interference cancellation (SIC) technique performs is a primary issue in realizing an in-band full-duplex (FD) wireless communication system. One factor affecting its performance is channel estimation error on the self-interference channel. We propose a new analog SIC scheme which is robust to channel estimation error. It uses phase rotators in the radio frequency (RF) chain. We also derive closed-form equations for the residual self-interference of the proposed and the conventional schemes. The analytical and numerical results show that the residual self-interference under the proposed SIC scheme is less than that using the conventional scheme, even though channel estimation error is present.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.101-103
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• 2018

최근 자원 효율성을 증대하기 위하여 차세대 유무선 통신시스템에서 동일대역 전이중 방식(in band full-duplex, FDX)을 채택하고 있다. 하지만 전이중 방식은 송수신이 동시에 이루어지기 때문에 하향신호와 상향신호가 더해져 수신된다. 따라서 원하는 신호를 수신하기 위해 자기간섭(SI: self-interference)으로 존재하는 하향 신호를 제거하는 기술이 요구된다. 본 논문에서는 주파수영역에서 자기간섭신호 제거(SIC: SI cancellation)하는 방법에 대해서 제안하고 실제 RF를 통과한 신호에 적용하여 성능을 분석한다.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.514-518
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• 2006

We have transferred highly stable 100 MHz RF through a 23 km fiber network. The fiber-induced phase noise due to the vibration and the temperature fluctuation in the optical path is detected and is compensated by configuring a noise-canceling servo. The transfer instability was $6{\times}10^{14}$ at 1 s of averaging time and $2{\times}10^{-17}$ at 10000 s of averaging time. The single sideband phase noise was greatly reduced by more than 20 dB below the Fourier frequency of 1 kHz. The transferred RF has nearly the same stability as the original reference frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.277-283
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• 2016

In this paper, a system of self-interference signal cancelation for in-band full duplex has been implemented and tested in RF/analog region. The system performance has been evaluated with NI5791 platform and NI Flex RIO. Due to the low power level of the NI5791, the RF signal is amplified by SKYWORKS SE2565T power amplifier. A circulator is used to feed the antenna both the transmitter and receiver. The RF FIR filter is designed by twelve delay taps in two different groups, and the interval between each delay tap is designed to have 100 ps. The amplified signal is distributed to antenna and the FIR filter by use of a 10 dB directional coupler. The tap coefficients of the RF FIR filter are tuned to estimate the self-interference signal coming from antenna reflection and the leakage of the circulator, and the self-interference signal is subtracted. The system is test with 802.11a/g 20 MHz OFMD at 2.56 GHz, and the output power of the amplifier of 0 dBm. The self-interference signal is canceled out by 53 dB.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.242-246
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• 2012

This paper presents an integrated low noise and highly linear wideband RF front-end for a digital terrestrial and cable TV tuner, which are used as a part of double-conversion TV tuner. The low noise amplifier (LNA) has a low noise figure and high linearity by adopting a noise canceling technique based on current amplification. The up-conversion mixer and SAW buffer have high linearity by employing a third order intermodulation cancellation technique. The proposed RF front-end is designed in a $0.18{\mu}m$ CMOS and draws 60 mA from a 1.8 V supply voltage. The RF front-end shows a voltage gain of 30 dB, an average single side-band noise figure of 4.2 dB, an IIP2 of 40 dBm, and an IIP3 of -4.5 dBm for the entire band from 48 MHz to 862Hz.

• Journal of the Korean institute of surface engineering
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• v.38 no.1
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• pp.7-13
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• 2005

Bismuth thin films were prepared on glass substrate with RF magnetron sputtering and effects of substrate temperature on surface morphology and their electrical transport properties were investigated. Grain growth of bismuth after nucleation and the onset of coalescense of grains at 393 K were observed with field emission secondary electron microscopy. Continuous thin films could not be obtained above 473 K because of grain segregation and island formation. Hall effect measurements showed that substrate heating yields the decrease of carrier density and the increase of mobility. Resistivity of bismuth film has its minimum (about 0.7 x 10/sup -3/ Ωcm) in range of 403～433 K. Annealing of bismuth films deposited at room temperature was carried out in a radiation furnace with flowing hydrogen gas. The change of resistivity was not significant due to cancellation of the decrease of carrier density and the increase of mobility. The abrupt change of electrical properties of film annealed above 523 K was found to be caused by partial oxidation of bismuth layer in x-ray diffraction analysis.

• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.116-125
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• 2003

In this paper, we introduce a newly developed DSP module and Software which Is applicable to DTV-OCR and is designed to cancel the interference signal. In general, RF repeater has problems of system oscillation and signal Quality degradation due to feedback interference signal coming from transmit antenna. In this paper, we demonstrate newly developed DSP HW and SW module for cancelling the interference signal by investigating the field data measured through a RF repeater. Also, the structure and signal processing method for non-regenerative repeater system based on the newly developed DSP HW and SW module is illustrated as well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1143-1153
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• 2010

In this paper, we propose an alternative method to increase the distortion cancellation bandwidth of an analog RF feedback power amplifier by using a negative group delay circuit(NGDC). A limited distortion cancellation bandwidth due to the group delay(GD) mismatch discouraged the use of feedback technique in spite of its powerful linearization performance. With the fabricated NGDC with positive phase slope over frequency, the feedback amplifier of the proposed topology experimentally achieved adjacent channel leakage ratio(ACLR) improvement of 15 dB over 50 MHz bandwidth at wideband code division multiple access(WCDMA) downlink band when tested with 2-carrier WCDMA signal. At an average output power of 28 dBm, ACLR of 25.1 dB is improved to obtain -53.2 dBc at 5 MHz offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.8
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• pp.632-639
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• 2018

This paper presents a single antenna radar sensor with a Ku-band radar transceiver IC realized by 130 nm CMOS processes. In this radar receiver, sensitivity time control using a DC offset cancellation feedback loop is employed to achieve a constant SNR, irrespective of distance. In addition, the receiver RF block has gain control to adjust high dynamic range. The RF output power is 9 dBm and the full chain gain of the Rx is 82 dB. To reduce the direct-coupled Tx signal to the Rx in a single antenna radar, a stub-tuned hybrid coupler is adopted instead of a bulky circulator. The maximum measured distance between the horn antenna and a metal plate target is 6 m.