A passive mobile location system for UMTS

Thomas, Norman; Cruickshank, D.G.M.

doi:10.1049/ic:19990291

Cited by 3 publications

(5 citation statements)

References 22 publications

(19 reference statements)

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“…3) The sequence is identically statistically independent (i.i.d), and is independent of the channel fading gain sequence . Then, it can be shown (see Appendix A) that at , the cost function is given by (6) where is the variance of the noise term .…”

Section: Parameter Optimization and Amplitude Estimationmentioning

confidence: 99%

“…We will now use this analysis to obtain an accurate estimate of the amplitude . Equation (6) shows that the amplitude of the output of our proposed estimation algorithm suffers from two biases. The first bias is an additive noise bias that increases with the noise variance.…”

Section: B Amplitude Estimationmentioning

confidence: 99%

“…and for a binary sequence , we have where we assumed, without loss of generality, that the pulseshape waveform is normalized such that . Substituting in (5), we obtain Expanding the sum over , squaring, applying the expectation operator, and using A.3), expression (6) From 1993 to 2001, he was with Motorola, Inc., as a Senior Engineer, Staff, Senior Staff, and Principal Staff Engineer. At Motorola, he worked at various groups focusing mainly on CDMA product development.…”

Section: Appendix Amentioning

confidence: 99%

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Robust wireless location over fading channels

Yousef

Sayed

Jalloul

2003

IEEE Trans. Veh. Technol.

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This paper develops an estimation algorithm for the time and amplitude of arrival of a known transmitted sequence over a single-path fading channel. The algorithm is optimized to enhance robustness to fast channel fading and low signal-to-noise ratio (SNR) conditions, which are common in wireless location applications. The paper also presents a noise and fading bias correction technique for amplitude of arrival estimation that improves the estimation accuracy significantly. The proposed algorithm is then applied to the case of code-division multiple-access (CDMA) wireless location finding for which the paper gives simulation results that demonstrate significant estimation accuracy improvement over known algorithms.

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Section: Parameter Optimization and Amplitude Estimationmentioning

confidence: 99%

Section: B Amplitude Estimationmentioning

confidence: 99%

Section: Appendix Amentioning

confidence: 99%

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Robust wireless location over fading channels

Yousef

Sayed

Jalloul

2003

IEEE Trans. Veh. Technol.

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“…In the second situation, where the pulses overlap, the location of the peak is obviously delayed relative to the location of the prompt ray. Such errors in the time-of-arrival are particularly damaging in wireless location applications (a topic of significant relevance nowadays-see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]). In these applications, small errors in the timeof-arrival can translate into many meters in terms of location inaccuracy.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Subchip Multipath Resolving for Wireless Location Systems

Yousef

Sayed

Khajehnouri

2006

EURASIP J. Adv. Signal Process.

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Reliable positioning of cellular users in a mobile environment requires accurate resolving of overlapping multipath components. However, this task is difficult due to fast channel fading conditions and data ill-conditioning, which limit the performance of leastsquares-based techniques. This paper develops two overlapping multipath resolving methods (adaptive and nonadaptive), and shows how the adaptive solution can be made robust to the above limitations by extracting and exploiting a priori information about the fading channel. Also the proposed techniques are extended when there are antenna arrays at the base station. Simulation results illustrate the performance of the proposed techniques.

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“…For example, the localization of a mobile phone can be done. 1 The localization of acoustic signals has gained interest recently, due to various applications. An efficient acoustic DOA estimation system has numerous applications in robotics, automated hearing and especially automatic surveillance.…”

Section: Introductionmentioning

confidence: 99%

A new method for outlier removal in time-delay-based direction of arrival estimates

2003

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Recently, the need to monitor restricted areas has increased. Acoustics is one of the available key techniques, but there are some restrictions and constraints to consider. In situations with unknown noise and low SNR the performance of time delay based direction of arrival (DOA) estimators collapses rapidly as SNR decreases. Outliers are introduced into estimation results when signals of interest are masked by noise.There exist several methods for compensation of noise induced errors, such as averaging within subarrays, time delay selection or various minimizations. These compensation methods provide an optimum solution with respect to some criteria, but are ineffective against large errors in multiple time delays.In this paper, we present a method for removing outliers caused by errors in time delays. First, we utilize signal propagation speed to measure an error criterion for DOA estimates. Second, estimates with sufficiently large error criterion are identified as outliers and discarded. We use an adaptive threshold to identify outliers.Effectiveness of our method is verified through experiments with simulations and real data. In both cases we are able to identify and discard outliers and thus improve estimation reliability. Results indicate that the given method can be used to gain efficiency and robustness in DOA estimation applications, such as automatic acoustic surveillance of large areas.

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A passive mobile location system for UMTS

Cited by 3 publications

References 22 publications

Robust wireless location over fading channels

Robust wireless location over fading channels

Adaptive Subchip Multipath Resolving for Wireless Location Systems

A new method for outlier removal in time-delay-based direction of arrival estimates

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