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Ching-sang Chiu - One of the best experts on this subject based on the ideXlab platform.
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south china sea internal tide internal waves impact on the temporal variability of horizontal Array Gain at 276 hz
IEEE Journal of Oceanic Engineering, 2004Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Theodore Schroeder, Ching-sang ChiuAbstract:The temporal variability of the spatial coherence of an acoustic signal received on a bottomed horizontal Array has been calculated for 276-Hz narrow-band signals. A conventional plane wave beamformer was applied to the received signals. The temporal variability of the Array's omnipower, beam power, and Array Gain are related to variability in the sound-speed field. The spectral characteristics of Array omnipower are nonstationary and changed as the spectral characteristics of the temperature field varied. The Array omnipower and beam-power variability tracked each other in time and varied by as much as 15 dB over time intervals as short as 7 min. Array Gain varied up to 5 dB and usually tracked the omnipower variability. A contiguous 24-h section of data is discussed in detail. This data section is from a time period during which the high-frequency fluid dynamic perturbation of the sound-speed field was of smaller amplitude than other sections of the 16-d data set. Consequently, this section of data sets an upper bound for the realizable Array Gain. The temporal variability of Array Gain and spatial coherence at times appears to be correlated with environmental perturbation of the sound-speed field, but are also correlated with changes in the signal-to-noise ratio. The data was acquired during the Office of Naval Research's South China Sea Asian Seas International Acoustics Experiment. The 465-m 32-channel horizontal Array was placed on the bottom in 120 m of water at the South China Sea shelf break. The acoustic source was moored in 114 m of water /spl sim/19 km from the receiving Array.
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South China Sea internal tide/internal waves-impact on the temporal variability of horizontal Array Gain at 276 Hz
IEEE Journal of Oceanic Engineering, 2004Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Theodore H. Schroeder, Ching-sang ChiuAbstract:The temporal variability of the spatial coherence of an acoustic signal received on a bottomed horizontal Array has been calculated for 276-Hz narrow-band signals. A conventional plane wave beamformer was applied to the received signals. The temporal variability of the Array's omnipower, beam power, and Array Gain are related to variability in the sound-speed field. The spectral characteristics of Array omnipower are nonstationary and changed as the spectral characteristics of the temperature field varied. The Array omnipower and beam-power variability tracked each other in time and varied by as much as 15 dB over time intervals as short as 7 min. Array Gain varied up to 5 dB and usually tracked the omnipower variability. A contiguous 24-h section of data is discussed in detail. This data section is from a time period during which the high-frequency fluid dynamic perturbation of the sound-speed field was of smaller amplitude than other sections of the 16-d data set. Consequently, this section of data sets an upper bound for the realizable Array Gain. The temporal variability of Array Gain and spatial coherence at times appears to be correlated with environmental perturbation of the sound-speed field, but are also correlated with changes in the signal-to-noise ratio. The data was acquired during the Office of Naval Research's South China Sea Asian Seas International Acoustics Experiment. The 465-m 32-channel horizontal Array was placed on the bottom in 120 m of water at the South China Sea shelf break. The acoustic source was moored in 114 m of water /spl sim/19 km from the receiving Array.
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Bottomed acoustic Array Gain variability in the South China Sea
The Journal of the Acoustical Society of America, 2003Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Ching-sang ChiuAbstract:The stratified sound speed field at the shelf break of the South China Sea is constantly perturbed by the tide and the passage of the internal tide, linear and nonlinear internal waves and associated fine structure. An 18‐day acoustic propagation experiment was performed at the shelf break in May 2001 as part of the ONR supported AsiaEx experiment. A 32‐element 465‐m bottomed horizontal Array received 300‐ and 500‐Hz center frequency FM acoustic signals from sources moored at a range of ∼18.9 km. The temporal and spatial variability of signal coherence, the Array Gain variability, and residual signal Gain variability has been extracted. Temporal and spatial variability of the signal coherence and Array Gain variability has a degree of correlation with temperature field variability measured near the source and receiver locations. These data as well as histograms of the residual Array Gain variability in time and space will be presented.
Marshall H. Orr - One of the best experts on this subject based on the ideXlab platform.
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south china sea internal tide internal waves impact on the temporal variability of horizontal Array Gain at 276 hz
IEEE Journal of Oceanic Engineering, 2004Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Theodore Schroeder, Ching-sang ChiuAbstract:The temporal variability of the spatial coherence of an acoustic signal received on a bottomed horizontal Array has been calculated for 276-Hz narrow-band signals. A conventional plane wave beamformer was applied to the received signals. The temporal variability of the Array's omnipower, beam power, and Array Gain are related to variability in the sound-speed field. The spectral characteristics of Array omnipower are nonstationary and changed as the spectral characteristics of the temperature field varied. The Array omnipower and beam-power variability tracked each other in time and varied by as much as 15 dB over time intervals as short as 7 min. Array Gain varied up to 5 dB and usually tracked the omnipower variability. A contiguous 24-h section of data is discussed in detail. This data section is from a time period during which the high-frequency fluid dynamic perturbation of the sound-speed field was of smaller amplitude than other sections of the 16-d data set. Consequently, this section of data sets an upper bound for the realizable Array Gain. The temporal variability of Array Gain and spatial coherence at times appears to be correlated with environmental perturbation of the sound-speed field, but are also correlated with changes in the signal-to-noise ratio. The data was acquired during the Office of Naval Research's South China Sea Asian Seas International Acoustics Experiment. The 465-m 32-channel horizontal Array was placed on the bottom in 120 m of water at the South China Sea shelf break. The acoustic source was moored in 114 m of water /spl sim/19 km from the receiving Array.
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South China Sea internal tide/internal waves-impact on the temporal variability of horizontal Array Gain at 276 Hz
IEEE Journal of Oceanic Engineering, 2004Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Theodore H. Schroeder, Ching-sang ChiuAbstract:The temporal variability of the spatial coherence of an acoustic signal received on a bottomed horizontal Array has been calculated for 276-Hz narrow-band signals. A conventional plane wave beamformer was applied to the received signals. The temporal variability of the Array's omnipower, beam power, and Array Gain are related to variability in the sound-speed field. The spectral characteristics of Array omnipower are nonstationary and changed as the spectral characteristics of the temperature field varied. The Array omnipower and beam-power variability tracked each other in time and varied by as much as 15 dB over time intervals as short as 7 min. Array Gain varied up to 5 dB and usually tracked the omnipower variability. A contiguous 24-h section of data is discussed in detail. This data section is from a time period during which the high-frequency fluid dynamic perturbation of the sound-speed field was of smaller amplitude than other sections of the 16-d data set. Consequently, this section of data sets an upper bound for the realizable Array Gain. The temporal variability of Array Gain and spatial coherence at times appears to be correlated with environmental perturbation of the sound-speed field, but are also correlated with changes in the signal-to-noise ratio. The data was acquired during the Office of Naval Research's South China Sea Asian Seas International Acoustics Experiment. The 465-m 32-channel horizontal Array was placed on the bottom in 120 m of water at the South China Sea shelf break. The acoustic source was moored in 114 m of water /spl sim/19 km from the receiving Array.
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Horizontal Array Gain variability measured on the New Jersey shelf during late fall and early winter propagation conditions—RAGS03
The Journal of the Acoustical Society of America, 2004Co-Authors: Bruce H. Pasewark, Marshall H. Orr, Altan Turgut, Jeffery A. Schindall, Michael Mccord, Earl W CareyAbstract:A conventional beamformer has been applied to 300 Hz CW and 300 Hz center frequency LFM acoustic signals received on a 96‐channel 465 m bottomed horizontal Array. The temporal history of the Array Gain for five subapertures (30, 60, 120, 240, 465 m) will be presented. The Gain of each subaperture varied over time scales ranging from less than 1 min to 13 days. The time dependence is being correlated to sound speed variability induced by shelf slope front movement, the internal tide, nonlinear internal waves and atmospheric forcing. The longer apertures did not achieve ideal Array Gain. Temporal variability of the horizontal spatial coherence lengths will be discussed. The acoustic sources were moored 18 m above the bottom in 64 m of water. The propagation path was cross shelf. The receiving Array was located near the New Jersey (USA) shelf break 20 km from the source. Water depth at the Array location was 89 m. [Work supported by ONR.]
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Bottomed acoustic Array Gain variability in the South China Sea
The Journal of the Acoustical Society of America, 2003Co-Authors: Marshall H. Orr, Bruce H. Pasewark, Stephen N. Wolf, James F. Lynch, Ching-sang ChiuAbstract:The stratified sound speed field at the shelf break of the South China Sea is constantly perturbed by the tide and the passage of the internal tide, linear and nonlinear internal waves and associated fine structure. An 18‐day acoustic propagation experiment was performed at the shelf break in May 2001 as part of the ONR supported AsiaEx experiment. A 32‐element 465‐m bottomed horizontal Array received 300‐ and 500‐Hz center frequency FM acoustic signals from sources moored at a range of ∼18.9 km. The temporal and spatial variability of signal coherence, the Array Gain variability, and residual signal Gain variability has been extracted. Temporal and spatial variability of the signal coherence and Array Gain variability has a degree of correlation with temperature field variability measured near the source and receiver locations. These data as well as histograms of the residual Array Gain variability in time and space will be presented.
Olivier Besson - One of the best experts on this subject based on the ideXlab platform.
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An alternative to diagonal loading for implementation of a white noise Array Gain constrained robust beamformer
Signal Processing, 2018Co-Authors: Olivier BessonAbstract:Diagonal loading is one of the most popular methods of robust adaptive beamforming, and the solution to many different problems aimed at producing beamformers which are robust to finite samples effects or/and steering vector errors. Among the latter, constraining the white noise Array Gain (WNAG) is a meaningful approach. However, relating the loading level to the desired WNAG is not straightforward. In this communication, using a generalized sidelobe canceler structure of the beamformer, we prove that the WNAG constraint can be encoded directly in the beamformer, and the latter can be obtained in a rather simple way from a specific eigenvector and without going through the diagonal loading step.
Josef A. Nossek - One of the best experts on this subject based on the ideXlab platform.
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WCNC - Limits of Transmit and Receive Array Gain in Massive MIMO
2020 IEEE Wireless Communications and Networking Conference (WCNC), 2020Co-Authors: Tobias Laas, Josef A. NossekAbstract:In this paper, we consider the transmit and receive antenna Array Gain of massive MIMO systems. In particular, we look at their dependence on the number of antennas in the Array, and the antenna spacing for uniform linear and uniform circular Arrays. It is known that the transmit Array Gain saturates at a certain antenna spacing, but the receive Array Gain had not been considered. With our physically consistent analysis based on the Multiport Communication Theory, we show that the receive Array Gain does not saturate, but that there is a peak at a certain antenna spacing when there is no decoupling network at the receiver. As implementing a decoupling network for massive MIMO would be almost impossible, this is a reasonable assumption. Furthermore, we analyze how the Array Gain changes depending on the antenna spacing and the size of the antenna Array and derive design recommendations.
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Transmit and receive Array Gain of uniform linear Arrays of isotrops
2009 IEEE Sarnoff Symposium, 2009Co-Authors: Michel T. Ivrlac, Josef A. NossekAbstract:Both in the signal processing and in the information theory literature, it is common to assume that the Array Gain of antenna Arrays grows linearly with the number of antennas. However, such an assertion is valid only when the antennas are uncoupled. When antenna coupling is present and properly taken into account by the signal processing algorithms, we show that both the transmit and the receive Array Gain can grow super-linearly with the number of antennas. In special cases, the receive Array Gain can even grow exponentially with the antenna number. These results are exciting, for they imply that the potential of radio communication systems which use more than one antenna at the receiver or the transmitter, is likely to be much higher than previously reported.
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The maximum achievable Array Gain under physical transmit power constraint
2008 International Symposium on Information Theory and Its Applications, 2008Co-Authors: Michel T. Ivrlac, Josef A. NossekAbstract:In this paper, we derive the maximum achievable Array Gain of a uniform linear antenna Array with isotropic radiators under physical transmit power constraint in three different propagation scenarios: line-of-sight, Rayleigh fading, and constant non-line-of-sight. It turns out that the achievable Array Gain is larger than is claimed in previously reported results, which do not take the physical transmit power into account. We show that the maximum achievable Array Gain can increase proportional to the square of the number of transmit antennas for line-of-sight, and also for Rayleigh fading with not too large an angle-spread. In case of some special, constant non-line-of-sight scenarios, the Array Gain can even grow exponentially with the number of transmit antennas. These result are exciting, for they imply that the potential of multi-antenna communication systems can be much higher than previously reported.
Seong Oun Hwang - One of the best experts on this subject based on the ideXlab platform.
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spectral efficiency augmentation in uplink massive mimo systems by increasing transmit power and uniform linear Array Gain
Sensors, 2020Co-Authors: Jehangir Arshad, Abdul Rehman, Ateeq Ur Rehman, Rehmat Ullah, Seong Oun HwangAbstract:Improved Spectral Efficiency (SE) is a prominent feature of Massive Multiple-Input and Multiple-Output systems. These systems are prepared with antenna clusters at receiver (Rx) and transmitter (Tx). In this paper, we examined a massive MIMO system to increase SE in each cell that ultimately improves the area throughput of the system. We are aiming to find appropriate values of average cell-density (D), available bandwidth (B), and SE to maximize area throughput because it is the function of these parameters. Likewise, a SE augmentation model was developed to attain an increased transmit power and antenna Array Gain. The proposed model also considers the inter-user interference from neighboring cells along with incident angles of desired and interfering users. Moreover, simulation results validate the proposed model that is implementable in real-time scenarios by realizing maximum SE of 12.79 bits/s/Hz in Line of Sight (LoS) and 12.69 bits/s/Hz in Non-Line of Sight (NLoS) scenarios, respectively. The proposed results also substantiate the SE augmentation because it is a linear function of transmit power and Array Gain while using the Uniform Linear Array (ULA) configuration. The findings of this work ensure the efficient transmission of information in future networks.