• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.47 no.5
• /
• pp.100-105
• /
• 2010

A multi-band low noise amplifier (LNA) is designed in 90 nm RF CMOS process for 3GPP LTE (3rd Generation Partner Project Long Term Evolution) applications. The designed multi-band LNA covers the eight frequency bands between 1.85 and 2.8 GHz. A tunable input matching circuit is realized by adopting a switched capacitor array at the LNA input stage for providing optimum performances across the wide operating band. Current steering technique is adopted for the gain control in three steps. The performances of the LNA are verified through post-layout simulations (PLS). The LNA consumes 17 mA at 1.2 V supply voltage. It shows a power gain of 26 at the normal gain mode, and provides much lower gains of 0 and -6.7 in the bypass-I and -II modes, respectively. It achieves a noise figure of 1.78 dB and a IIP3 of -12.8 dBm over the entire band.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.71-79
• /
• 2010

The algorithm of multiple channel signal processing requires the flexibility of variable frequency band, efficient allocation of transmission power, and flexible frequency band reallocation to satisfy various service types which requires different transmission rates and frequency band. This paper proposes an improved multiple channel signal processing for converting the frequency band of multiple carrier signals efficiently using a window function and DFT in the time domain. In contrast to the previous algorithm of multiple-channel signal processing performing band-pass signal processing in the frequency domain, the proposed algorithm is a method of block signal processing using a window function in the time domain. In addition, the complexity of proposed algorithm of the window function is lower than that of the previous algorithm performing signal processing in the frequency domain, and it performs the frequency band transform efficiently. The computer simulation result shows that the perfect reconstruction of output signal and the flexible frequency band reallocation is performed efficiently by the proposed algorithm.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.127-130
• /
• 2004

기존의 전대역(Full-Band)에서 특징 파라미터를 추출하는 화자 확인(Speaker Verification) 시스템은 저대역이나 고대역에서 화자 정보의 특징이 제거되기 쉽다. 또한, 주파수 스펙트럼에 부분적으로 오염이 되는 경우, 특징 파라미터를 왜곡시켜 화자 확인 시스템의 성능을 저하시킨다. 본 논문에서는 이러한 문제점을 해결하기 위해 다중대역 공분산 모델(Covariance Model)을 제안한다. 제안한 방법은 주파수 영역에서 전대역을 여러 개의 부대역(Sub-Band)으로 분할하고, 부대역별로 독립적으로 특징 파라미터를 추출하여 공분산 모델을 구한다. 제안된 방법의 성능 확인을 위하여 공분산 모델 간의 거리를 측정하는 화자 확인 실험을 하였다. 잡음 환경에서 기존의 방법인 전대역에 기반한 공분산 모델과 제안한 방법을 비교 분석한 결과, 제안한 방법이 기존 방법보다 $2\%$정도 성능이 향상되었다. 또한, 제안된 방법은 전대역에 기반한 파라미터 차원 수를 다중대역의 개수로 분할하여 사용하므로 계산량의 감소와 저장 공간면에서 효율적이다.

• Journal of Advanced Navigation Technology
• /
• v.15 no.6
• /
• pp.1008-1014
• /
• 2011

In this paper, multi-band fractal microstrip patch antenna which is possible for WLAN band and WiMax band is designed and made. For multi-resonance of developed antenna, resonance frequency, impedance matching, polarity and reflection pattern can mad perfectly, then to make satisfied multi-independent frequency three kind of half circle fractal patch is inserted. In the situation continuously happening half circle in designed structure, antennas one of half-circle band is shown.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.3
• /
• pp.292-300
• /
• 2010

In this paper, we propose a RF front-end architecture based on hybrid conversion which is available to receive both broadband and multiband DVB-H receiver, and a multi-function circuit for implementing the RF front-end is fabricated. A multi-function circuit is operated as a sub-harmonic mixer mode in the case of receiving a broadband VHF/UHF band, which show a conversion loss of -10.0 dB, noise figure of 7.0 dB and IIP3 of 2.0 dBm. On the other hand, it is performed as a attenuation mode with a insertion loss of -10.0 dB in receiving a multiband, L-band.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.4
• /
• pp.51-54
• /
• 2015

많은 무선 스마트 단말의 보급으로 무선 데이터 트래픽이 폭발적으로 증가해 왔고, 이로 인한 주파수 자원의 부족은 피할 수 없는 문제가 되었다. 본 과제에서는 획득한 인지정보를 기반으로 하여 다중 라디오 환경에서 주파수 스펙트럼 감지, 동적 스펙트럼 할당, 다중 라디오 선택 및 다중화, 최적 자원 할당, 적응형 전송 기술을 개발하였고, 이 기술들의 개발로 추가적인 주파수 사용 없이 주파수 사용 효율을 최대화함으로써 네트워크 성능 향상을 이끌어 내었다. 본 기술은 고유 주파수 대역 접속, 공통 주파수 대역 접속, 고유/공통 주파수 대역 동시 접속의 경우로 나누어 개발되었다. 개발된 기술은 사용자의 QoS(Quality of Service)를 만족하는 동시에 네트워크 성능 향상을 이끌어낼 수 있음을 모의실험을 통해 검증하였다. 따라서 본 연구의 결과는 4G뿐만 아니라, 5G에서 핵심적인 기술 개발의 중요한 역할을 담당할 것이며, 앞으로도 추가적인 연구가 필요하다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.4
• /
• pp.772-779
• /
• 2015

In this paper,a reconfigurable multi-band mobile antenna with switching line for LTE band 13, GSM, K-PCS, WCDMA band. The proposed antenna is planar strip line design and composed of stub shorted to the ground plane and two switching line for proposed band operation. To obtain the optimized parameters, we used the simulator, Using the obtained parameters is fabricated. The numerical and experiment results demonstrated that the proposed antenna satisfied the -6 dB impedance bandwidth requirement while simultaneously covering when the state of sw1 and sw2 on for LTE band 13, the state of sw1 off and sw2 on for GSM, K-PCS, the state of sw1 off and sw2 off for WCDMA. Respectively and characteristics of gain and radiation patterns are determined for a reconfigurable multi-band mobile terminal.

• Journal of Navigation and Port Research
• /
• v.39 no.6
• /
• pp.473-478
• /
• 2015

In this paper, we suggest a flexible multiband antenna which can be equipped on an inflatable life-jacket. The antenna can send distress alert and location data of survivors to assist rescue operation when crew or people are in distress. The antenna operate in three frequency bands such as VHF-DSC band (156MHz), COSPAS-SARSAT band (406MHz) and GPS band (1,575MHz). The GPS band is implemented with a square ring-slot planar antenna, the COSPAS-SARSAT band and the VHF-DSC band antenna is implemented by monopole type. In order to give flexibility of substrate to be equipped on life-jacket, FR4-epoxy substrate of thickness 0.2mm is used to make antenna. The reflection coefficients of the fabricated antenna are -8.8dB, -20.4dB and -10.7dB at each bandwidth like VHF-DSC, COSPAS-SARSAT and GPS band, respectively, when people are wearing life-jacket integrated multiband antenna.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.7 no.4
• /
• pp.188-194
• /
• 2014

In this paper, an antenna which has quad band in LTE (0.746 ~ 0.798 GHz), GSM(0.824 ~ 0.960 GHz), DCS(1.71 ~ 1.88 GHz), WCDMA(1.91 ~ 2.17 GHz) is proposed. An antenna size is $122mm{\times}50mm{\times}0.8mm$ on FR4(${\epsilon}_r=4.4$) ground substrate. In the proposed antenna, branch line is applied to the conventional PIFA architecture to achieve multi-bandwidth. Coupling power supply is applied for a wide bandwidth. Result of the measurement is as follows. When the low frequency, the antenna presents gain of 0.93 ~ 1.92dBi, and radiation efficiency of 49.60 ~ 76.35 %, and When the high frequency, gain is 2.19 ~ 4.66dBi, and radiation efficiency is 60.40 ~ 80.01 %, and with a VSWR < 2 (${\leq}-10dB$)measurement results for standard satisfies all band. Judging from the result, proposed multiband antenna is expected to be applied. B4G mobile terminals since the antenna shows an outstanding performance.

• KIPS Transactions on Computer and Communication Systems
• /
• v.12 no.10
• /
• pp.299-308
• /
• 2023

As the spectrum shortage problem has accelerated by the emergence of various services, New Radio-Unlicensed (NR-U) has appeared, allowing users who communicated in licensed bands to communicate in unlicensed bands. However, NR-U network users reduce the performance of Wi-Fi network users who communicate in the same unlicensed band. In this paper, we aim to simultaneously maximize the fairness and throughput of the unlicensed band, where the NR-U network users and the WiFi network users coexist. First, we propose an optimal power allocation scheme based on Monte Carlo Policy Gradient of reinforcement learning to maximize the sum of rates of NR-U networks utilizing rate-splitting multiple access in unlicensed bands. Then, we propose a channel occupancy time division algorithm based on sequential Raiffa bargaining solution of game theory that can simultaneously maximize system throughput and fairness for the coexistence of NR-U and WiFi networks in the same unlicensed band. Simulation results show that the rate splitting multiple access shows better performance than the conventional multiple access technology by comparing the sum-rate when the result value is finally converged under the same transmission power. In addition, we compare the data transfer amount and fairness of NR-U network users, WiFi network users, and total system, and prove that the channel occupancy time division algorithm based on sequential Raiffa bargaining solution of this paper satisfies throughput and fairness at the same time than other algorithms.