• 제어로봇시스템학회논문지
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• 제20권8호
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• pp.890-894
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• 2014

In this paper, we derive the CRLB (Cramer-Rao Lower Bound) of effective carrier-to-noise power ratio ($C/N_0$) estimation for a GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal under band-limited white noise jamming environments. The quality of a received GPS signal is commonly described in terms of its $C/N_0$, implying that the noise is white and thus can be described by scalar noise density. However, if some intentional interference is received to a victim GPS receiver, then the $C/N_0$ is no longer the efficacious performance indicator. The correct and straightforward measurement to analyze the receiving situation is the effective $C/N_0$. In this paper, we consider a band-limited white noise jamming whose bandwidth is 2MHz and is the same as one of the first null-to-null bandwidth of the GPS L1 C/A signal.

• 한국음향학회지
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• 제36권3호
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• pp.218-227
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• 2017

본 논문에서는 배열센서에서 DOA(Direction Of Arrival)를 수행하는 경우 크래머 라오 하한을 이용하여 표적신호가 수신되는 방위오차의 최소분산을 계산하고, 탐지 방위오차 및 위치추정 거리오차를 추정하는 방안을 제시한다. 신호 대 잡음비는 DOA의 정확도 즉, 표적의 탐지 방위오차 및 위치추정 거리오차를 결정한다. 일반적으로 신호대 잡음비는 음원준위, 소음준위, 전달손실, 배열센서의 형상, 빔 조향 방위에 따라 달라진다. 표적의 공간상 상대적 위치와 소음준위가 달라지는 경우, 신호 대 잡음비의 변화에 따른 탐지 방위오차 및 위치추정 거리오차를 확률적으로 추정하는 몬테카를로 시뮬레이션을 수행함으로써, 제안된 방법을 검증하였다.

• Journal of the Korean Statistical Society
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• 제22권1호
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• pp.1-12
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• 1993

An approach to make the information bound sharper in median-unbiased estimation, based on an analogue of the Cramer-Rao inequality developed by Sung et al. (1990), is introduced for continuous densities with a nuisance parameter by considering information quantities contained both in the parametric function of interest and in the nuisance parameter in a linear fashion. This approach is comparable to that of improving the information bound in mean-unbiased estimation for the case of two unknown parameters. Computation of an optimal weight corresponding to the nuisance parameter is also considered.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.426-434
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• 2015

In this paper we proposed a dada-aided Doppler estimation method for underwater acoustic communication. The training sequence is non-dedicate, hence it can be designed for Doppler estimation as well as channel equalization. We assume the channel has been equalized and consider only flat-fading channel. First, based on the training symbols the theoretical received sequence is composed. Next the least square principle is applied to build the objective function, which minimizes the error between the composed and the actual received signal. Then an iterative approach is applied to solve the least square problem. The proposed approach involves an outer loop and inner loop, which resolve the channel gain and Doppler coefficient, respectively. The theoretical performance bound, i.e. the Cramer-Rao Lower Bound (CRLB) of estimation is also derived. Computer simulations results show that the proposed algorithm achieves the CRLB in medium to high SNR cases.

• International Journal of Advanced Culture Technology
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• 제2권2호
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• pp.15-18
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• 2014

This paper presents a sensor location decision making method respect to Container-Grown Seedlings in view of precision agriculture (PA) when sensors involved in tree container measure received signal strength (RSS) or time-of-arrival (TOA) between themselves and neighboring sensors. A small fraction of sensors in the container-grown seedlings system have a known location, whereas the remaining locations must be estimated. We derive Rao-Cramer bounds and maximum-likelihood estimators under Gaussian and log-normal models for the TOA and RSS measurements, respectively.

• ETRI Journal
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• 제38권3호
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• pp.560-567
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• 2016

To solve the problem of parameter optimization in image sensor-based visible light positioning systems, theoretical limits for both the location and the azimuth angle of the image sensor receiver (ISR) are calculated. In the case of a typical indoor scenario, maximum likelihood estimations for both the location and the azimuth angle of the ISR are first deduced. The Cramer-Rao Lower Bound (CRLB) is then derived, under the condition that the observation values of the image points are affected by white Gaussian noise. For typical parameters of LEDs and image sensors, simulation results show that accurate estimates for both the location and azimuth angle can be achieved, with positioning errors usually on the order of centimeters and azimuth angle errors being less than $1^{\circ}$. The estimation accuracy depends on the focal length of the lens and on the pixel size and frame rate of the ISR, as well as on the number of transmitters used.

• 한국전자파학회논문지
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• 제28권10호
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• pp.819-824
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• 2017

본 논문은 distributed Multi-input Multi-output(MIMO) 레이다 시스템에서 다수의 송 수신기 조합으로부터 얻어진 Time of Arrival(ToA) 정보들을 이용하여 표적의 위치를 추정하는 기법을 제안한다. 제안된 기법은 테일러 선형 근사를 반복적으로 수행함으로써 임의의 초기 값으로부터 표적의 위치를 추정한다. 시뮬레이션 결과는 제안된 알고리즘이 기존 표적 위치 추정 기법들보다 더 향상된, 더 나아가 Cramer-Rao Lower Bound(CRLB)에 도달하는 평균제곱오차(MSE) 성능을 가지는 것을 보여준다.

• The Journal of the Acoustical Society of Korea
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• 제17권3E호
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• pp.22-26
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• 1998

This paper proposes a simple method to measure system's performance in target tracking problems. Essentially employing the Cramer-Rao Lower Bound (CRLB) on tracking accuracy, an algorithm of predicting system's performance under various scenarios is developed. The input data is a collection of measurements over tim from sensors embedded in Gaussian noise. The target of interest may not maneuver over the processing time interval while the own ship observing platform may maneuver in an arbitrary fashion. The proposed approach is demonstrated and discussed through simulation results.

• International Journal of Reliability and Applications
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• 제2권3호
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• pp.189-197
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• 2001

The estimation of mean lifetimes in presence of interval censoring with mixed replacement procedure is examined when the distributions of lifetimes are exponential. It is assumed that, due to physical restrictions and/or economic constraints, the number of failures is investigated only at several inspection times during the lifetime test; thus there is interval censoring. The maximum likelihood estimator is found in an implicit form. The Cramor-Rao lower bound, which is the asymptotic variance of the estimator, is derived. The estimation of mean lifetimes for competing failures model has been expanded.

• Journal of the Korean Statistical Society
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• 제15권2호
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• pp.87-96
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• 1986

Sequential estimation of parameters in a compound Poisson process whose jump sizes are one-parameter exponential class random variables is discussed. Cramer-Rao type information inequality is used as an efficiency cirterion. Unbiased estimators for certain parametric functions whose variance attain the lower bound are all characterized with the corresponding sampling plans.