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Simplified Non-Square Quadrature Amplitude Modulation Demapper for DOCSIS 3.1
Lee, Jewon,Jung, Joon-Young,Ahn, Jae Min [Institute of Electrical and Electronics Engineers 2017 IEEE transactions on broadcasting Vol.63 No.1
<P>A simplified soft demapper for non-square quadrature amplitude modulation (QAM) provided by fifth generation of highspeed data-over-cable systems (DOCSIS 3.1) is proposed. By using the geometric tendency of the non-square QAM constellation and 'fold-and-overlap' approach, the non-linear log likelihood ratio (LLR) equation based on the max-log maximum a posteriori (MAP) algorithm can be approximated to linear equations. With this approximation, the proposed method can be applied to high-order non-square QAM, up to 8192 QAM, with negligible bit error rate performance degradation under additive white Gaussian noise and multipath flat-fading channels. Computational complexity is reduced by at least 93% compared to the LLR calculation based on the max-log MAP algorithm.</P>
Navigation Signals Based on Orthogonal Tiered Polyphase Code
Lee, Jewon,Kim, Jeong-been,Kim, Kap-jin,Song, Ki-won,Ahn, Jae Min The Institute of Positioning 2015 Journal of Positioning, Navigation, and Timing Vol.4 No.3
A navigation signal based on orthogonal tiered polyphase code was proposed. For the proposed signal, tiered polyphase code was used as the code of a pilot channel. Tiered polyphase code is a complex number type code, and thus the pilot channel and data channel were separated using the Walsh code which makes the correlation between different codes become 0. The results of the simulation indicated that the correlation characteristics and signal acquisition performance of the proposed signal were identical to those of tiered polyphase code, and that the disadvantage of tiered polyphase code could be supplemented through a data channel in terms of signal tracking.
An Efficient Localization Method using RFID Tag Floor Localization and Dead Reckoning
Jewon Lee,Youngsu Park,Daehyun Kim,Minho Choi,Taedong Goh 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
A method for using radio-frequency identification tag floor based localization (RFTL) for indoor mobile robot localization is proposed. This method does not suffer from illumination or line of sight impairment issue, and it is less affected by the environment than is conventional localization. However, it faces an inherent limitation, in terms of its low accuracy. To overcome this problem, an efficient localization method using RFTL and dead reckoning is presented. To utilize this method, it is important to find a model of map for the tag recognition probabilities. With this in mind, this paper proposes two model structures: a deterministic ellipse model, and a two variable Gaussian random variable (RV) model. The results of experiments to verify and compare the performances of these two model structure methods are presented.
불균일 Tag Floor 상에서의 전송신호 전력 조절을 통한 RFID 위치추정
이제원(Jewon Lee),박영수(Youngsu Park),김대현(Daehyun Kim),김상우(Sang Woo Kim) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
위치추정은 현재 이동로봇 분야에서 매우 중요하게 다루어 지는 문제이다. RFID 위치추정 시스템은 저렴하고, 오차누적의 위험이 없고, map과 같은 사전정보의 제약이 없기에 범용적으로 사용될 수 있다. 하지만 RFID 위치추정에 있어, tag들의 서로 다른 인식거리 차이는 위치추정의 오차를 증폭시키는 역할을 한다. 따라서 이 논문에서는 이를 극복하기 위해 tag들의 인식거리 정보를 활용하여 위치추정을 수행한다. 또한 보다 정확한 위치추정을 위해, 송신신호 전력조절을 통하여, 인식거리를 조절하는 방법을 사용한다. 이들의 성능은 simulation을 통해서 확인하였다.