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Lee, Taehyun,Sim, Dongkyu,Seo, Bongsung,Lee, Chungyong IEEE 2019 IEEE Transactions on Vehicular Technology VT Vol.68 No.1
<P>This paper proposes a channel estimation scheme for the filter-bank multicarrier systems with quadrature amplitude modulation (FBMC-QAM). Under frequency selective channels, the adjacent data symbols cause interference to the pilot symbols in FBMC-QAM systems and degrade the performance of the channel estimation. To handle this problem, we analyze the interference of the pilot symbols in an oversampled frequency domain before the receiver filtering process. Exploiting the interference analysis, we propose a pilot symbol configuration and condition of filter coefficients to cancel the inter-carrier interference. Moreover, we apply a time domain data symbol precoding to eliminate inter-symbol interference. The simulation results show that the proposed scheme outperforms conventional channel estimation schemes.</P>
A Signal-level Channel Equalization for FBMC-QAM Systems
Taehyun Lee,Chungyong Lee 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
We propose a signal-level minimum mean square error (MMSE) equalization structure for filter-bank multicarrier (FBMC) systems to transmit quadrature amplitude modulation (QAM) symbols. In order to mitigate the residual interference, we consider interference channels from the other subcarriers and symbol intervals. Simulation results show that the proposed equalization structure has similar bit error rate (BER) performance in multipath fading channels compared to the conventional signal-level full matrix receiver structure with reducing the size of equalization matrix.
Bumsoo Lee,Chungyong Lee IEEE 2015 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.14 No.1
<P>We analyze the performance of a cooperative multi-hop network with an incremental hop selection (IHS) scheme. Generally, multiple-relay networks based on half-duplex-mode relays undergo spectral efficiency loss due to the use of multiple time phases. The IHS scheme can prevent this problem because it increases the number of hops only when the currently selected path cannot support the target performance. Moreover, we apply an adaptive modulation technique to the IHS scheme to determine the additional spectral efficiency gain while maintaining the target performance. We evaluate the average spectral efficiency and the outage probability performances over the Nakagami-m fading channel. Also, the diversity and coding gains are derived through the asymptotic outage probability in the high transmit SNR region.</P>
FBMC-QAM 시스템에 적합한 이중 모드 인덱스 변조 기술
이태현(Taehyun Lee),이충용(Chungyong Lee) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.11
In this paper, we introduce the filter-bank multicarrier (FBMC) system based dual mode index modulation (DM) scheme and propose the index modulation with signal level channel equalization, which can provide robustness to intrinsic interference of FBMC system. Simulation result shows that the proposed FBMC-DM system can have robustness against interference with the FBMC-DM system without equalization, and confirms the validity of the proposed dual mode index modulation.
다중 홉 네트워크를 위한 적응 변조 기반 증분형 홉 선택 기법의 성능 분석
이범수(Bumsoo Lee),김도훈(Dohoon Kim),이충용(Chungyong Lee) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.11
본 논문에서는 반이중 다중 홉 네트워크에서 스펙트럼 효율성 성능을 향상시킬 수 있는 적응 변조 기반의 증분형 홉 선택기법을 제안하고 성능을 분석한다. 제안 하는 기법은 다중 홉 네트워크에서 동작하므로 넓은 네트워크 커버리지를 보장하면서도 반이중 방식에 따른 추가 시간 슬롯 사용의 빈도를 낮추어서 스펙트럼 효율성 손실을 막아준다. 우리는 본 논문에서는 제안하는 기법의 평균 스펙트럼 효율성 성능을 나카가미-m 채널에서 분석하였다. 모의실험 결과는 제안하는 기법의 우수성과 분석 된 성능의 정확함을 보여준다. This paper proposes an adaptive modulation based incremental hop selection scheme which improves network coverage in half-duplex multi-hop networks. The proposed scheme guarantees wide coverage through the operation of multi-hop network while preventing spectral efficiency loss due to the usage of multiple time phases in the half-duplex protocol. Also, we evaluate the average spectral efficiency performance over Nakagami-m fading channel. The simulation results show that the proposed scheme outperforms the existing schemes and the derived evaluation is valid.
무선 주파수 신호와 단말 내장 센서를 이용한 심층 신경망 기반 융합 측위 기법
이현욱(Hyunwook Lee),임채훈(Chaehun Im),장수환(Suhwan Jang),이충용(Chungyong Lee) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6
We propose an enhanced pedestrian localization based on a deep neural network. The input of DNN comprises estimated positioning parameters from built in sensors of mobile devices and radio frequency signal, such as step information, heading, and distances between device and access points (APs). By adopting DNN, the limitations of existing probability-based method, computation complexity and noise variance knowledge requirement, can be releaved. Moreover, simulation results show that the proposed localization method is more precise than the comparative method.