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A novel PAPR reduction scheme for OFDM systems: selective mapping of partial tones (SMOPT)
Yoo, Seungsoo,Yoon, Seokho,Kim, Sun Yong,Song, Iickho IEEE 2006 IEEE transactions on consumer electronics Vol.52 No.1
A novel scheme called the selective mapping of partial tones (SMOPT) is addressed for the reduction of the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The SMOPT first produces a set of modified OFDM symbols with reduced PAPRs by adding a set of mapping symbols designed on peak reduction tones (PRT) to the original OFDM symbol. The SMOPT then selects the symbol with the lowest PAPR for transmission among the modified OFDM symbols. When simulated under the IEEE 802.11a wireless local area network and ETSl EN 300 401 digital audio broadcasting physical layer models, the SMOPT is observed to have lower sensitivity to PRT positions, lower complexity, and more design flexibility than the tone reservation scheme.
Seungsoo Yoo,Youngyoon Lee,Seokho Yoon,Sun Yong Kim 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
This paper proposes a generalized advanced region correlation (G-ARC) scheme for BOC(m, n) modulated code tracking, and demonstrates tracking bias and running average in static channels. The correlation values between the time-delayed pseudo noise code and received signal remain almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we have proposed the advanced region correlation (ARC) scheme. However, the ARC scheme uses only one ARC branch. So, the energy of the other sub-peaks is wasted. To tackle this problem, we proposed a generalized the ARC scheme that exploits all sub-peaks for BOC(m, n) modulated spreading code tracking.
A Novel Tracking Scheme for Galileo BOC(1,1) System
Seungsoo Yoo,Euihyoung Lee,Seokho Yoon,Sun Yong Kim 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
The delay lock loop with early minus late discriminator (EL-DLL) is the most widely used tracking scheme in direct sequence spread spectrum (DS/SS) systems. In multipath environments, it has tracking bias, which is a residual error after fine code synchronization. The correlation function of the binary offset carrier (BOC) modulated spreading signal has several time corresponding to the several local minimum and maximum correlation values. This paper will present a novel tracking scheme for the Galileo BOC(1,1) system using this characteristic and will show its performance via simulation.
좌부엽 상관값을 이용한 대역 제한된 직접수열 확산대역 시스템의 추적편이 완화 기법
유승수(Seungsoo Yoo),정상효(Sanghyo Jung),윤석호(Seokho Yoon),김선용(Sun Yong Kim) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
대역 제한된 DS/SS 시스템의 상관 함수는 최고 값이 나타나는 시점과 함께 이른 또는 늦은 상관시간 옵셋 영역에서 극소 또는 극대로 나타나는 시점을 특징점으로 갖는다. 이 가운데 이른 상관시간옵셋 영역의 상관 함수는 다중경으로 신호에 의해 덜 왜곡되기 때문에 이 영역의 상관 함수를 이용해 부호 동기를 추적하여 유지할 수 있다면 EL-DLL (delay lock loop with early minus late discriminator) 보다 추적편이를 줄일 수 있다. 본 논문에 이런 특성을 이용하는 추적편이 완화 기법을 제안하고, 모의실험을 통해 성능을 알아본다.
MBOC(6,1,4/33) 신호의 다중경로 영향 완화를 위한 새로운 Strobe 펄스 설계
유승수(Seungsoo Yoo) 제어로봇시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.11
In this paper, we propose a novel strobe pulse to mitigate the multipath effect of MBOC (6,1,4/33) signal and analyze its performance. By additionally modulating a passband Direct Sequence/Spread Spectrum (DS/SS) signal with a Binary Offset Carrier (BOC) sub-carrier, the signal band can be moved to a desired band, thereby increasing frequency efficiency. In addition, the correlation characteristics of the correct code synchronization point are improved, so that the multipath effect can be reduced to compare with the existing Binary Phase Shift Keying (BPSK) modulated signal. However, the multipath effect is still one of the major performance limitations of the Global Navigation Satellite Systems (GNSSs). A conventional scheme to mitigate multipath effects of GNSS is the Strobe pulse technique. In this paper, we design a new strobe pulse that can effectively mitigate the multipath effects of MBOC (6,1,4/33) signals, and multipath mitigation in the 2-Ray model, a representative channel environment to assess the multipath mitigation performance by computer-based simulation. In order to compare the performance of the proposed new strobe pulse, the W2 pulse scheme with similar implementation complexity is considered. The W2 pulse technique is the one of the Strobe pulse technique for BOC signal. Based on the output of the discriminator in multipath free environment, the pull-in range of the W2 pulse technique is about 0.2 chips, whereas the proposed scheme is about 0.6 chips, which is about 3 times wider. And the false-lock point of the proposed scheme is less than about 20% to compare the W2 scheme. In the same environment, the multipath error envelope of the W2 and the proposed schemes is shown, and both techniques are affected only by the closed-in multipath signal. Among them, the proposed scheme has significantly lower multipath errors due to the closed-in multipath signal compared to the W2 technique, and the maximum value of the proposed scheme based on the running average of the multipath errors is about 32% compared to the W2 scheme.
강한 광대역정규잡음 환경에서 GPS 상용 수신기 양자화기의 변환 손실 분석
유승수(Seungsoo Yoo),김선용(Sun Yong Kim) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.9(통신이론)
본 논문에서는 강한 광대역정규잡음 환경에서 송신한 확산신호와 수신기에서 발생한 확산신호의 동기에 따른 2비트 비균등 양자화기의 변환손실을 (conversion loss) 분석하고, 이를 통해 변환손실이 최소인 2비트 비균등 양자화기의 출력은 ±1, ±3이고, 양자화 간격은 재밍 대 신호 전력비로 근사화할 수 있음을 보인다. This paper has derived the conversion loss according to the synchronized condition between the transmitted and locally generated spreading signals for the civil global positioning system (GPS) receiver in the heavy wideband Gaussian noise environments. From this, the outputs of the 2-bit nonuniform quantizer, which has the minimum conversion loss, is set to ±1 and ±3, while the quantization step size is approximated to the jamming-to-signal power ratio.