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정교원(Kyowon Jung),왕한호(Hanho Wang) 한국정보기술학회 2019 한국정보기술학회논문지 Vol.17 No.3
This paper proposes a detection algorithm for high-order modulations using the K-means clustering, a representative clustering algorithm in the unsupervised learning research area. The conventional clustering QPSK detection scheme has problems in clustering because it can not apply the scheme of selecting the initial center point to higher order modulation schemes. On the other hand, the detection scheme proposed in this paper solves the problem by applying a sequential clustering technique to the conventional detection scheme. In this paper, the detection performance is verified through the mean square error and the symbol error rate between the estimated center point and the reference point. The detection performance is determined by the number of received symbols and the initial center point scheme and is verified by simulations result that the number of symbols required to achieve similar performance to ML increases as the modulation order increases.
Link Adaptation with SNR Offset for Wireless LAN Systems
김찬홍,정교원,고경준,이정우,Kim, Chan-Hong,Jeong, Kyo-Won,Ko, Kyeong-Jun,Lee, Jung-Woo The Korean Institute of Communications and Informa 2011 韓國通信學會論文誌 Vol.36 No.10A
Link Adaptation should select the best modulation and coding scheme (MCS) which gives the highest throughput as channel conditions vary. Several link adaptation algorithms for wireless local area network (WLAN) have been proposed but for the future WLAN systems such as 802.11n system, these algorithms do not guarantee the best performance. In this paper, we propose a new link adaptation algorithm in which an MCS level is chosen by the received SNR plus the offset value obtained from the transmission results. The performance of proposed algorithm is simulated by an IEEE 802.11n system. From the analysis, we conclude the proposed algorithm performs better than the well-known link adaptation algorithms such as auto rate fallback and general SNR-based techniques. Particularly, the proposed algorithm improves throughput when the packet error ratio (PER) is constrained for fast fading channels. 링크 적응 기법은 변하는 채널 조건에 맞는 최적의 MCS 레벨을 선택한다. 무선 LAN 시스템을 위한 다양한 링크 적응 알고리즘이 제안되었으나 802.11n과 같은 최근의 시스템에서 최적의 성능을 보장하지는 않는다. 본 논문에서는 수신 SNR과 전송 결과에 따라 얻어지는 오프셋 값을 이용한 새로운 링크 적응 알고리즘을 제안한다. 802.11n 시스템에서 모의실험을 하여 제안된 알고리즘과 잘 알려져 있는 ARF 및 일반적인 SNR기반 알고리즘과 그 성능을 비교해본다. 제안된 알고리즘은 PER에 제한이 있는 경우 시변채널에서 더 좋은 성능을 보인다.