Monitoring harsh environments such as underwater scenarios or aircraft external surfaces pertains to important applications like assisted navigation and tactical surveillance;nevertheless, it poses additional challeng...
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ISBN:
(纸本)1424403081
Monitoring harsh environments such as underwater scenarios or aircraft external surfaces pertains to important applications like assisted navigation and tactical surveillance;nevertheless, it poses additional challenges compared with standard applications. At Transducers2005 we presented a wired addressing architecture of distributed sensors for monitoring real-time in-situ pressure variations in underwater environment that faces the above-mentioned issues. this architecture consists in a double array of identical and interconnected smart nodes monitoring a matrix of passive sensors. I n this paper, we present an analysis of the delay model related to the presented architecture and a calculation of the overall frame-rate of the system as a function of the geometrical topology of the arrays. the topology of the network, i.e. the length of each bus and the number of nodes, can be chosen according to the application, and directly affects the global capacitive load on the serial lines. Each serial line can be schematized with a distributed RC model for the flat cable plus a lumped capacitance for each smart node. then, a 3(rd)-order pi-segmented model of O'Brien-Savarino [4] is calculated for a 16-block fine with block length equal to 0.3m. thanks to that, the global time per iteration is calculated on each bus as well as the scanning time of the whole matrix and the frame rate for the system as a function of sensor distribution and of the aspect ratio of the matrix. this model can be employed to identify the optimal arrangement for the sensor matrix and smart node arrays.
Reconfigurable Intelligent Surface (RIS) can improve the channel quality by smartly reconfiguring the wireless communication environment and has therefore received extensive research attention. In this paper, we propo...
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ISBN:
(纸本)9781665406338
Reconfigurable Intelligent Surface (RIS) can improve the channel quality by smartly reconfiguring the wireless communication environment and has therefore received extensive research attention. In this paper, we propose to deploy the programmable metasurface at the base station of a cellular wireless communication system to formulate an active RIS system termed the pattern reconfigurable multi-input multi-output (PRMIMO), which can modify the propagation environment actively by reconfiguring the radiation pattern of the transmit antenna array. We focus on the capacity maximization pattern design in PR-MIMO systems, where SDR-based solutions with Gaussian randomization are first discussed. We further propose an eigenvalue optimization based pattern design scheme and a heuristic closed-form scheme based on the physical mechanism of the reconfigurable pattern on the wireless channel. Numerical results demonstrate that active radiation pattern design leads to an improved capacity performance for PR-MIMO over traditional MIMO systems with fixed radiation characteristics.
Close-in sensing is needed for urban warfare operations, where Ground Moving Target Indication (GMTI) could be provided via forward or rear-facing multi-function array radars mounted on small highly-maneuverable airbo...
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ISBN:
(纸本)1424403081
Close-in sensing is needed for urban warfare operations, where Ground Moving Target Indication (GMTI) could be provided via forward or rear-facing multi-function array radars mounted on small highly-maneuverable airborne platforms. However, airborne radar arrays oriented any direction other than side-looking cause an elevation dependent angle-Doppler relationship in the clutter returns. this non-stationarity is acute in close-in sensing geometries where elevation diversity exists over the scene of interest. However, planar arrays have an inherent advantage over linear arrays due to their ability to observe clutter statistics as a function of elevation. this paper demonstrates the utility of elevation diversity by synthesizing a single 3D-STAP filter that exhibits an elevation dependent azimuth-Doppler response which is tailored to null the clutter "bowl" which characterizes the forward-looking clutter spectrum. Such a capability is particularly exploitable on transmit, where all elevation angles are simultaneously illuminated. To demonstrate potential benefits, this paper proposes the use of recently developed Space Time Illumination Patterns (STIP) from a planar AESA to invoke elevation diverse space-time illumination in a forward-looking clutter scenario. It is shown that 3D-STIP (azimuth-elevation-Doppler) facilitates elevation specific space-time beamforming which removes the clutter energy from a given Doppler frequency across all ranges, potentially simplifying processing on receive. Simulations using synthesized training data and clairvoyant covariance knowledge are conducted to demonstrate proof-of-concept.
In this paper, we consider an optimal finite-alphabet non-orthogonal multiple access (NOMA) design for a multiuser multi-input single-output (MISO) visible light communication (VLC) broadcast system when channel state...
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this paper develops the theory of a MEMS nonplanar intrinsically beamforming ultrasonic sensor microarray. the microarray exploits the geometrical properties of a doubly ruled surface to realize a constant beamwidth b...
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