http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Frequency divided group beamforming with sparse spacefrequency code for above 6 GHz URLLC systems
Chanho Yoon(Chanho Yoon),Woncheol Cho(Woncheol Cho),Kapseok Chang(Kapseok Chang),Young-Jo Ko(Young-Jo Ko) 한국전자통신연구원 2022 ETRI Journal Vol.44 No.6
In this study, we propose a limited feedback-based frequency divided group beamforming with sparse space-frequency transmit diversity coded orthogonal frequency division multiplexing (OFDM) system for ultrareliable low latency communication (URLLC) scenario. The proposed scheme has several advantages over the traditional hybrid beamforming approach, including not requiring downlink channel state information for baseband precoding, supporting distributed multipoint transmission structures for diversity, and reducing beam sweeping latency with little uplink overhead. These are all positive aspects of physical layer characteristics intended for URLLC. It is suggested in the system to manage the multipoint transmission structure realized by distributed panels using a power allocation method based on cooperative game theory. Link-level simulations demonstrate that the proposed scheme offers reliability by achieving both higher diversity order and array gain in a nonline-of-sight channel of selectivity and limited spatial scattering.
Chanho Yoon,Hoojin Lee,Joonhyuk Kang IEEE 2014 IEEE Communications Letters Vol.18 No.4
<P>In this letter, an efficient method of evaluating the performance of space-time block codes (STBCs) from symmetrically structured coordinate interleaved orthogonal designs (CIODs) is presented over generalized-K MIMO fading channels. By effectively approximating the moment generating function (MGF), we derive approximate closed-form expressions for the symbol pairwise error rate (SPER) and corresponding tight approximate symbol error rate (SER) of STBCs from symmetric CIODs. Finally, various Monte-Carlo simulations are performed to validate our theoretical results.</P>
An IIR based Low Complexity Timing Synchronization Method for Spread Spectrum Systems
Chanho Yoon(윤찬호),Hoojin Lee(이후진) 한국정보기술학회 2013 Proceedings of KIIT Conference Vol.2013 No.5
본 논문에서는 복잡도가 낮은 무한 임펄스 응답 필터를 기반으로 한 타이밍 동기 추정 방법을 제시하고자 한다. Monte-Carlo 실험을 통해 AWGN만 있는 채널의 경우 ideal한 성능에 도달하는 것을 보이며 일반적인 multipath fading 채널 환경에서 반송파 주파수 오차가 있는 경우에도 robust한 성능을 나타낸다. In this paper, we propose a low complexity infinite impulse response (IIR) filter based moving average block timing synchronization method for spreaded systems operating at extremely low SNR region. By comparing the performance of the synchronization schemes and Monte-Carlos simulation results, we validate that our low complexity solution performs extremely well at very low SNR and approaches that of an ideal case in AWGN only channel.
Combined ML and DFE Decoding for Coded Double STBC-OFDM System
Chanho Yoon,Hoojin Lee,Joonhyuk Kang IEEE 2010 IEEE Communications Letters Vol.14 No.12
<P>An efficient combined maximum likelihood (ML) and decision feedback equalization (DFE) decoding method is proposed for a coded double space-time block code orthogonal frequency division multiplexing (DSTBC-OFDM) system. For the missing bit log likelihood ratios (LLRs) in the DFE part, our proposed detector effectively exploits Gaussian approximated LLRs with reference to the colored noise covariance matrix. Simulation results demonstrate that the proposed method can achieve comparable performance to the coded full ML detectors with deterministic and lower complexity.</P>
Chanho Yoon,Hoojin Lee,Joonhyuk Kang IEEE 2011 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.60 No.3
<P>In this correspondence, we evaluate the symbol error rate (SER) and information outage probability (IOP) of space-time block codes (STBCs) from coordinate interleaved orthogonal designs (CIODs) in the composite channel of lognormal shadowing and Rayleigh fading. By applying the Gauss-Hermite quadrature integration, we derive an accurate closed-form approximation for the symbol pairwise error rate (SPER) and corresponding tight upper and lower bounds on the SER of STBCs from CIODs. An accurate closed-form approximate formula for the IOP is also derived by formulating the composite squared lognormal/chi-square probability density function and exploiting the high-signal-to-noise-ratio (SNR) approximation technique. Furthermore, we investigate the achievability of full diversity in Rayleigh fading channels with shadowing effects. Finally, various Monte Carlo simulations are performed to validate our theoretical results.</P>