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1
Emery, Charles D., H. C. Casey, and Stephen W. Smith. "Ultrasonic Imaging Using Optoelectronic Transmitters." Ultrasonic Imaging 20, no. 2 (1998): 113–31. http://dx.doi.org/10.1177/016173469802000203.
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Conventional ultrasound scanners utilize electronic transmitters and receivers at the scanner with a separate coaxial cable connected to each transducer element in the handle. The number of transducer elements determines the size and weight of the transducer cable assembly that connects the imaging array to the scanner. 2-D arrays that allow new imaging modalities to be introduced significantly increase the channel count making the transducer cable assembly more difficult to handle. Therefore, reducing the size and increasing the flexibility of the transducer cable assembly is a concern. Fiber optics can be used to transmit signals optically and has distinct advantages over standard coaxial cable to increase flexibility and decrease the weight of the transducer cable for large channel numbers. The use of fiber optics to connect the array and the scanner entails the use of optoelectronics such as detectors and laser diodes to send and receive signals. In transmit, optoelectronics would have to be designed to produce high-voltage wide-bandwidth pulses across the transducer element. In this paper, we describe a 48 channel ultrasound system having 16 optoelectronic transmitters and 32 conventional electronic receivers. We investigated both silicon avalanche photodiodes (APD's) and GaAs lateral photoconductive semiconductor switches (PCSS's) for producing the transmit pulses. A Siemens SI-1200 scanner and a 2.25 MHz linear array were used to compare the optoelectronic system to a conventional electronic transmit system. Transmit signal results and images in tissue mimicking phantoms of cysts and tumors are provided for comparison.
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O'Toole, A. C., K. J. Murchie, C. Pullen, et al. "Locomotory activity and depth distribution of adult great barracuda (Sphyraena barracuda) in Bahamian coastal habitats determined using acceleration and pressure biotelemetry transmitters." Marine and Freshwater Research 61, no. 12 (2010): 1446. http://dx.doi.org/10.1071/mf10046.
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Documenting free-swimming fish in their natural environment using acoustic transmitters equipped with acceleration and pressure sensors may contribute to knowledge of locomotory behaviour for a variety of aquatic species. Previously, collection of acceleration data has been limited to archival loggers, necessitating retrieval of the devices; however, recent advances in biotelemetry have allowed for acceleration data to be transmitted to a remote receiver. To illustrate the application of this technology, relative locomotory activity and depth utilisation of adult great barracuda (Sphyraena barracuda) were monitored across habitat types and diel periods using acoustic transmitters equipped with tri-axial acceleration and pressure sensors within an acoustic telemetry array (n = 53 receivers) deployed in The Bahamas. Although there were no differences in acceleration or depth use across habitats or diel periods, there was evidence of movement into shelf habitat during mid-day where they occupied depths >10 m. Given both the method of calculating the accelerometer output, and that the transmitters were unable to store and transmit large quantities of data, we suggest choosing transmitter settings with a short average delay and high transmission frequency to optimise data quality and resolution. This paper represents one of the first reports of the use of telemetered acceleration values from free-swimming fish.
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Tweneboah-Koduah, Samuel, Emmanuel Ampoma Affum, Kwame Agyemang-Prempeh Prempeh Agyekum, Sunday Adeola Ajagbe, and Matthew O. Adigun. "Performance of Cooperative Relay NOMA with Large Antenna Transmitters." Electronics 11, no. 21 (2022): 3482. http://dx.doi.org/10.3390/electronics11213482.
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The potential of the Non-Orthogonal Multiple Access (NOMA) approach for wireless communications in the fifth generation (5G) and beyond can not be underestimated. This is because users with favorable channel conditions can serve as relays to improve system performance by employing Successive Interference Cancellation (SIC). Lately, the combination of NOMA and the cooperative relay has attracted the interest of researchers. The analysis of cooperative relay NOMA (CR-NOMA) with a massive multiple-input multiple-output (mMIMO) system is mainly based on theoretical channel models such as the correlated-based stochastic channel model (CBSM) even though the geometric-based stochastic channel model (GBSM) has been found to provide better, practical and realistic channel properties. This, in our view, is due to computational challenges. Again, the performance of CR-NOMA systems using the GBSM channel model with large antenna transmitters and network coding schemes has attracted little attention in academia. Therefore, the need to study mMIMO CR-NOMA that considers channel properties such as path-loss, delay profile and tilt angle has become vital. Furthermore, the co-existing of large antenna transmitters with coding schemes needs further investigation. In this paper, we study the performance of a two-stage mMIMO CR-NOMA network where the transmitter is represented as a uniform rectangular array (URA) or cylindrical array (CA). The communication channel from the transmitter (TX) to the user equipment (UE) through a relay station (RS) is modeled with a 3GPP’s three-dimensional (3D) GBSM mMIMO channel model. To improve the analytical tractability of 3D GBSM, we defined the antenna element location vectors using the physical dimension of the antenna array and incorporated them into the 3D channel model. Bit-error rates, achievable rates and outage probabilities (OP) are examined using amplify-and-forward (AF) and decode-and-forward (DF) coding schemes. Results obtained show with fixed power allocation and SNR of 20 dB, far or weak users can attain a high achievable rate using DF and URA. Again, from the results, the combination of AF and CA presents better outage probabilities. Finally, the results indicate that the performance difference between CBSM and GBSM is marginal, even though the proposed 3D GBSM channel model has a higher degree of random parameters and computational complexities.
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Shirai, Toshimichi, Tomoaki Oyama, Hiroshi Imai, and Shinsuke Abe. "Search for Extraterrestrial Intelligence at 22 GHz with the Very Large Array." Symposium - International Astronomical Union 213 (2004): 423–28. http://dx.doi.org/10.1017/s0074180900193647.
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We have conducted a direct Search for Extraterrestrial Intelligence at the Water Maser frequency, 22.235 GHz, using the Very Large Array. The targets were 13 solar-type stars that were known to host exoplanetary systems. In all cases, the RMS limits of the flux density, 20 mJy (5σ), were sufficient to rule out any omnidirectional transmitters of the same power as terrestrial radars (5 × 1012 W). We discuss the significance of this non-detection.
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Kurdzo, James M., Boon Leng Cheong, Robert D. Palmer, Guifu Zhang, and John B. Meier. "A Pulse Compression Waveform for Improved-Sensitivity Weather Radar Observations." Journal of Atmospheric and Oceanic Technology 31, no. 12 (2014): 2713–31. http://dx.doi.org/10.1175/jtech-d-13-00021.1.
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Abstract The progression of phased array weather observations, research, and planning over the past decade has led to significant advances in development efforts for future weather radar technologies. However, numerous challenges still remain for large-scale deployment. The eventual goal for phased array weather radar technology includes the use of active arrays, where each element would have its own transmit/receive module. This would lead to significant advantages; however, such a design must be capable of utilizing low-power, solid-state transmitters at each element in order to keep costs down. To provide acceptable sensitivity, as well as the range resolution needed for weather observations, pulse compression strategies are required. Pulse compression has been used for decades in military applications, but it has yet to be applied on a broad scale to weather radar, partly because of concerns regarding sensitivity loss caused by pulse windowing. A robust optimization technique for pulse compression waveforms with minimalistic windowing using a genetic algorithm is presented. A continuous nonlinear frequency-modulated waveform that takes into account transmitter distortion is shown, both in theory and in practical use scenarios. Measured pulses and weather observations from the Advanced Radar Research Center’s dual-polarized PX-1000 transportable radar, which utilizes dual 100-W solid-state transmitters, are presented. Both stratiform and convective scenarios, as well as dual-polarization observations, are shown, demonstrating significant improvement in sensitivity over previous pulse compression methods.
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Plotkin, A., and E. Paperno. "3-D magnetic tracking of a single subminiature coil with a large 2-D array of uniaxial transmitters." IEEE Transactions on Magnetics 39, no. 5 (2003): 3295–97. http://dx.doi.org/10.1109/tmag.2003.816750.
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Lamoral Coines, Adrián, and Víctor P. Gil Jiménez. "CCSDS 131.2-B-1 Transmitter Design on FPGA with Adaptive Coding and Modulation Schemes for Satellite Communications." Electronics 10, no. 20 (2021): 2476. http://dx.doi.org/10.3390/electronics10202476.
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Satellite communications are a well-established research area in which the main innovation of last decade has been the use of multi-carrier modulations and more robust channel coding techniques. However, in recent years, novel advanced signal processing has started being developed for these communications due to the increase in the signal processing capacity of transmitters and receivers. Although signal processing capabilities are increasing, they are still constrained by large limitations because these techniques need to be implemented in real hardware, thus making complexity a matter of critical importance. Therefore, this paper presents the design and implementation of a transmitter with adaptable coding and modulation on a field-programmable-gate-array (FPGA). The main motivation came from the standard CCSDS 131.2-B-1 which recommends that such a novel transmitter which has to date not been implemented in a real system The system was modeled by MATLAB with the purpose of being programmed in VHDL following the AXI-stream protocol between components. Behavioral simulation results were obtained in VIVADO and compared with MATLAB for verification purposes. The transmitter logical circuit was synthesized in a FPGA Zynq Ultrascale RFSoC ZU28DR, showing low resource consumption and correct functioning, leading us to conclude that the deployment of new communication systems in state-of-the-art hardware in satellite communications is justified.
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Rechisky, Erin L., David W. Welch, Aswea D. Porter, Melinda C. Jacobs, and Adrian Ladouceur. "Experimental measurement of hydrosystem-induced delayed mortality in juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) using a large-scale acoustic array." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 7 (2009): 1019–24. http://dx.doi.org/10.1139/f09-078.
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Out-migrating Snake River salmon smolts must pass eight major hydro dams before reaching the Pacific Ocean. Direct mortality at the dams is generally low; however, the cumulative stress caused by dam passage is hypothesized to result in delayed mortality, which occurs beyond the impounded section of the river. We tested the delayed mortality hypothesis by comparing in-river and early ocean survival of hatchery-origin spring Chinook salmon ( Oncorhynchus tshawytscha ) from the Snake River to a mid-Columbia River population that passes through only four dams and has higher smolt to adult return rates. Smolts >140 mm fork length were implanted with acoustic transmitters and tracked with the Pacific Ocean Shelf Tracking (POST) array to as far as Alaska. There was no detectable difference in survivorship to the first ocean detection line, 274 km beyond the final dam (SSnake = 29% ± 4%, SYakima = 28% ± 5%), indicating that the survival disparity observed in adult return rates may develop later in the marine life history phase. Our study is the first to estimate survival in the coastal ocean and demonstrates the utility of a large-scale array in testing previously intractable hypotheses.
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Klinard, Natalie V., Aaron T. Fisk, Steven T. Kessel, Edmund A. Halfyard, and Scott F. Colborne. "Habitat use and small-scale residence patterns of sympatric sunfish species in a large temperate river." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 7 (2018): 1059–69. http://dx.doi.org/10.1139/cjfas-2017-0125.
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Bluegill (Lepomis macrochirus) and pumpkinseed (Lepomis gibbosus) sunfish function as a trophic link between invertebrates and piscivores in temperate freshwater food webs, but little is known about their movement in large-scale riverine ecosystems. To address this, pumpkinseed and bluegill were implanted with acoustic transmitters and monitored for 5 months (June to November 2015) within a 0.39 km2 acoustic array in the Detroit River. Residence index analysis revealed site fidelity of sunfish to the side of the river they were tagged and a lack of movement across a shipping channel. Bluegill were more active at night and pumpkinseed more active during daylight hours, possibly partitioning resources on a temporal basis, unlike in smaller lakes where the species partition the littoral and pelagic habitats. Pumpkinseed presence was positively correlated with water temperature and level, whereas bluegill presence was not related to any environmental parameters examined. This study demonstrates that anthropogenic alterations (e.g., channelization) influence the movement and distribution of fishes and that fish behaviour in a large river ecosystem can differ from smaller temperate lakes.
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Starr, Richard M., Victoria O'Connell, Stephen Ralston, and Laurence Breaker. "Use of Acoustic Tags to Estimate Natural Mortality, Spillover, and Movements of Lingcod (Ophiodon elongatus) in a Marine Reserve." Marine Technology Society Journal 39, no. 1 (2005): 19–30. http://dx.doi.org/10.4031/002533205787521677.
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Advances in electronic telemetry systems have led to fish tagging studies that are sufficiently long to provide estimates of natural mortality of many marine fishes. We used acoustic transmitters and an array of recording receivers to estimate natural mortality, residence times, and rates of movements of lingcod (Ophiodon elongatus) in a marine reserve in southeast Alaska. We surgically implanted acoustic tags in a total of 83 lingcod in December 1999 and July 2000, and distributed recording monitors with receiving ranges of at least 800 m throughout the reserve. The receivers were anchored on the seafloor in locations that resulted in overlapping receiving ranges, and thus created an array of receivers that completely encompassed an 8 km2 reserve. In this way, we were able to estimate natural mortality rates and track movements of tagged lingcod into and out of the reserve from December 1999 through October 2001. Acoustic tag results indicated that most of the tagged fish frequently left the reserve, but were only absent for short time periods. Tagged fish showed a high degree of site fidelity. The large number of signals received from tagged fish enabled us to generate models that provided a way to predict the effects of marine reserves on yield and eggs per recruit for a cohort of female lingcod.
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Broto, Wisnu, Noor Suryaningsih, and Adhi Mahendra. "WORKING ANALYSIS OF SPACE TIME TRELLIS CODE ON WIFI MIMO(2X2) SYSTEM OFDM." Spektra: Jurnal Fisika dan Aplikasinya 6, no. 3 (2021): 159–74. http://dx.doi.org/10.21009/spektra.063.03.
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Wireless communication nowadays requires a system with reliable performance, efficient use of bandwidth, efficient power, and better coverage because it is in line with human needs for applications that require high and fast data rates. One of the concepts and methods to meet these needs is using an antenna technique with many transmitters and receivers or often called Multiple Input Multiple Output (MIMO), by adding a strategy at the time of delivery, namely the Space-Time Coding (STC) technique. In addition, the application of Orthogonal Frequency Division Multiplexing (OFDM) on MIMO-STC will more efficiently use bandwidth. The Space-Time Trellis Code (STTC) method is one of the diverse techniques in sending data with complex coding so that coding reinforcement is achieved and applied to the OFDM MIMO system. It is hoped that a system with reliable performance can be achieved. The simulation that is carried out presents the STTC and OFDM schemes on multi antennas (2 transmitters x 2 receivers) with a Combiner and Maximum Likelihood Sequence Estimator (MLSE) detection algorithm on the receiver. It is to get the quality of the sending signal in the performance analysis of Bit Error Rate (BER) with Signal to Noise Ratio (SNR). The simulation results are shown by modulation with M-array Phase Shift Keying (MPSK) and the number of symbols sent by giving different input parameter values. The results show that the number of carriers and the size of the Fast Fourier Transform (FFT) is large, and the modulation type with a small constellation produces a low BER and throughput at high SNR.
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Spangler, Steven R., and Catherine A. Whiting. "Radio remote sensing of the corona and the solar wind." Proceedings of the International Astronomical Union 4, S257 (2008): 529–41. http://dx.doi.org/10.1017/s1743921309029834.
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AbstractModern radio telescopes are extremely sensitive to plasma on the line of sight from a radio source to the antenna. Plasmas in the corona and solar wind produce measurable changes in the radio wave amplitude and phase, and the phase difference between wave fields of opposite circular polarization. Such measurements can be made of radio waves from spacecraft transmitters and extragalactic radio sources, using radio telescopes and spacecraft tracking antennas. Data have been taken at frequencies from about 80 MHz to 8000 MHz. Lower frequencies probe plasma at greater heliocentric distances. Analysis of these data yields information on the plasma density, density fluctuations, and plasma flow speeds in the corona and solar wind, and on the magnetic field in the solar corona. This paper will concentrate on the information that can be obtained from measurements of Faraday rotation through the corona and inner solar wind. The magnitude of Faraday rotation is proportional to the line of sight integral of the plasma density and the line-of-sight component of the magnetic field. Faraday rotation provides an almost unique means of estimating the magnetic field in this part of space. This technique has contributed to measurement of the large scale coronal magnetic field, the properties of electromagnetic turbulence in the corona, possible detection of electrical currents in the corona, and probing of the internal structure of coronal mass ejections (CMEs). This paper concentrates on the search for small-scale coronal turbulence and remote sensing of the structure of CMEs. Future investigations with the Expanded Very Large Array (EVLA) or Murchison Widefield Array (MWA) could provide unique observational input on the astrophysics of CMEs.
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Knight, Samantha M., Grace M. Pitman, D. T. Tyler Flockhart, and D. Ryan Norris. "Radio-tracking reveals how wind and temperature influence the pace of daytime insect migration." Biology Letters 15, no. 7 (2019): 20190327. http://dx.doi.org/10.1098/rsbl.2019.0327.
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Insects represent the most diverse and functionally important group of flying migratory animals around the globe, yet their small size makes tracking even large migratory species challenging. We attached miniaturized radio transmitters (less than 300 mg) to monarch butterflies ( Danaus plexippus ) and common green darner dragonflies ( Anax junius ) and tracked their autumn migratory movements through southern Ontario, Canada and into the United States using an automated array of over 100 telemetry towers. The farthest estimated distance a monarch travelled in a single day was 143 km at a wind-assisted groundspeed of 31 km h −1 (8.7 m s −1 ) and the farthest estimated distance a green darner travelled in a single day was 122 km with a wind-assisted groundspeed of up to 77 km h −1 (21.5 m s −1 ). For both species, increased temperature and wind assistance positively influenced the pace of migration, but there was no effect of precipitation. While limitations to tracking such small animals remain, our approach and results represent a fundamental advance in understanding the natural history of insect migration and environmental factors that govern their movements.
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Smith, David R., Brousseau Lorne J., Mary T. Mandt, and Michael J. Millard. "Age and sex specific timing, frequency, and spatial distribution of horseshoe crab spawning in Delaware Bay: Insights from a large-scale radio telemetry array." Current Zoology 56, no. 5 (2010): 563–74. http://dx.doi.org/10.1093/czoolo/56.5.563.
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Abstract To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent (>100 km), we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were >70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of first spawning was 4 days earlier for every 1 degree (̊C) rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by >5 km. Between years, most (77%) did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern (NJ) shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats.
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Stocks, Jerom R., Charles A. Gray, and Matthew D. Taylor. "Out in the wash: spatial ecology of a temperate marine shallow rocky-reef species derived using acoustic telemetry." Marine and Freshwater Research 66, no. 6 (2015): 559. http://dx.doi.org/10.1071/mf14182.
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Characterising the movement and habitat affinities of fish is a fundamental component in understanding the functioning of marine ecosystems. A comprehensive array of acoustic receivers was deployed at two near-shore coastal sites in south-eastern Australia, to examine the movements, activity-space size and residency of a temperate rocky-reef, herbivorous species Girella elevata. Twenty-four G. elevata individuals were internally tagged with pressure-sensing acoustic transmitters across these two arrays and monitored for up to 550 days. An existing network of coastal receivers was used to examine large-scale movement patterns. Individuals exhibited varying residency, but all had small activity-space sizes within the arrays. The species utilised shallow rocky-reef habitat, displaying unimodal or bimodal patterns in depth use. A positive correlation was observed between wind speed and the detection depth of fish, with fish being likely to move to deeper water to escape periods of adverse conditions. Detection frequency data, corrected using sentinel tags, generally illustrated diurnal behaviour. Patterns of habitat usage, residency and spatial utilisation highlighted the susceptibility of G. elevata to recreational fishing pressure. The results from the present study will further contribute to the spatial information required in the zoning of effective marine protected areas, and our understanding of temperate reef fish ecology.
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Harding, D. J., D. T. Roberts, D. Sternberg, T. M. Mullins, M. J. Kennard, and R. G. Dwyer. "Flow-related migration, juvenile dispersal and gonad development in two co-occurring mullet species, Mugil cephalus and Trachystoma petardi, in a regulated river system." Marine and Freshwater Research 70, no. 8 (2019): 1105. http://dx.doi.org/10.1071/mf18365.
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Catadromous fish species often use elevated flows to migrate from freshwater to downstream spawning grounds. However, in regulated river systems, artificial barriers and flow alteration can disrupt movement cues, affecting fish migration. Using a combination of acoustic telemetry, passive integrated transponder (PIT) tags and gonad maturity data, we assessed the migratory timing and flow requirements for downstream spawning migrations and upstream dispersal in two co-occurring mullet species in the Logan River, eastern Australia. Over 4 years, 141 adult sea mullet (Mugil cephalus) and 28 adult pinkeye mullet (Trachystoma petardi) were implanted with acoustic transmitters and broad-scale movements tracked using an array of 49 acoustic receivers. Juvenile upstream dispersal was monitored using implanted PIT tags and readers deployed in weir fishways. Sea mullet and pinkeye mullet undertook large-scale downstream migrations from February to March. Movements past weirs only occurred once sufficient flow had occurred and, in the case of pinkeye mullet, when gonads were mature. In contrast, juvenile dispersal into upstream habitats occurred primarily between November and April on low flows. This study advances our understanding of bidirectional movement ecology and flow requirements of two co-occurring mullet species to inform environmental flow management (e.g. to facilitate fish passage) in a regulated river system.
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Oldenburg, Douglas W., Eldad Haber, and Roman Shekhtman. "Three dimensional inversion of multisource time domain electromagnetic data." GEOPHYSICS 78, no. 1 (2013): E47—E57. http://dx.doi.org/10.1190/geo2012-0131.1.
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We present a 3D inversion methodology for multisource time-domain electromagnetic data. The forward model consists of Maxwell’s equations in time where the permeability is fixed but electrical conductivity can be highly discontinuous. The goal of the inversion is to recover the conductivity-given measurements of the electric and/or magnetic fields. The availability of matrix-factorization software and high-performance computing has allowed us to solve the 3D time domain EM problem using direct solvers. This is particularly advantageous when data from many transmitters and over many decades are available. We first formulate Maxwell’s equations in terms of the magnetic field, [Formula: see text]. The problem is then discretized using a finite volume technique in space and backward Euler in time. The forward operator is symmetric positive definite and a Cholesky decomposition can be performed with the work distributed over an array of processors. The forward modeling is quickly carried out using the factored operator. Time savings are considerable and they make 3D inversion of large ground or airborne data sets feasible. This is illustrated by using synthetic examples and by inverting a multisource UTEM field data set acquired at San Nicolás, which is a massive sulfide deposit in Mexico.
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Gillies, R. G., G. C. Hussey, G. J. Sofko, and H. G. James. "Relative O- and X-mode transmitted power from SuperDARN as it relates to the RRI instrument on ePOP." Annales Geophysicae 28, no. 3 (2010): 861–71. http://dx.doi.org/10.5194/angeo-28-861-2010.
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Abstract. The Cascade Demonstrator Small-Sat and Ionospheric Polar Explorer (CASSIOPE) satellite is scheduled to be launched in 2010. On board this satellite will be a suite of eight scientific instruments comprising the enhanced Polar Outflow Probe (ePOP). One instrument is the Radio Receiver Instrument (RRI) which will be used to receive HF transmissions from various ground transmitters such as the Super Dual Auroral Radar Network (SuperDARN) array. Magnetoionic polarization and propagation theory have been used to model the relative power that SuperDARN delivers to the Ordinary (O) and Extraordinary (X) modes of propagation. These calculations have been performed for various frequencies in the SuperDARN transmitting band and for all five Canadian based SuperDARN radars. The geometry of the radars with respect to the background magnetic field results in the X-mode dominating the transmitted signal when the modelled wave propagates northward and is nearly perpendicular to the magnetic field lines. Other propagation directions (i.e., above or southwards of the radar) results in propagation which is anti-parallel to the magnetic field lines and an equal splitting of transmitted power between the O- and X-modes occurs. The modelling analysis shows that for either high transmitting frequencies or low ionospheric electron densities, the range of latitudes that signal will be received is quite large (up to ~90° of latitude). Also for these conditions, the range of elevations where the X-mode signal strongly dominates the O-mode signal will be apparent in the received signal. Conversely, for lower transmitting frequencies or higher ionospheric electron densities, the latitudinal range that signal will be received over is smaller. Here the X-mode-only band is not apparent in the received signal as both modes will be received with roughly equal power. These relative mode power calculations can be used to characterize the average electron density content in the ionosphere or provide a measure of relative absorption in the D- and E-regions when the satellite passes through the field-of-view of a SuperDARN radar.
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Brignone, Stefano, Luca Minazzi, Christophe Molina, Tiziano Putelli, and Pietro Volta. "How Much Hatchery-Reared Brown Trout Move in a Large, Deep Subalpine Lake? An Acoustic Telemetry Study." Environments 11, no. 11 (2024): 245. http://dx.doi.org/10.3390/environments11110245.
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Fish movement into large, deep lakes has been rarely investigated due to the complexity and extent of such ecosystems. Among the different monitoring methods available, acoustic telemetry enables the study of the spatial ecology and behavior of aquatic organisms in lentic environments. In this study, the movement of 69 hatchery-reared adult brown trout (size 43–61 cm) marked with acoustic transmitters was monitored in the large and deep subalpine Lake Lugano (Switzerland and Italy). Trout were tracked for six consecutive months by seven acoustic receivers (March–August 2022), positioned in a non-overlapping array. Trout movement was reconstructed using R packages specific for acoustic telemetry (actel and RSP), which also allowed us to translate tracking information into utilization distribution (UD) areas for each fish. The effects of different environmental variables (rainfall, water discharge of the two main tributaries of Lake Lugano, atmospheric pressure, cloud coverage, and moon phases) on trout movement were tested, but none of these variables seemed to significantly correlate with fish movement. After release, most of the tagged fish exhibited reiterative movements during the initial month, with some maintaining this behavior throughout the entire study period. This spatial behavior can be particularly evident in hatchery-reared fish due to their aggressive and bold attitude. The association of these behavioral traits, shaped by domestication, could expose hatchery-reared fish to high risks and post-release mortality in the wild. Indeed, within a few months after the release, most of the tagged fish were no longer detected by the acoustic receivers. In addition, 26% of the total tagged fish were caught by recreational or professional fishermen.
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Kim, Gunzung, Imran Ashraf, Jeongsook Eom, and Yongwan Park. "Optimal Path Configuration with Coded Laser Pilots for Charging Electric Vehicles Using High Intensity Laser Power Beams." Applied Sciences 11, no. 9 (2021): 3826. http://dx.doi.org/10.3390/app11093826.
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Wireless power transmission (WPT) for wireless charging has been gaining wide attention as a promising approach to miniaturizing the battery size and increasing the maximal total range of an electric vehicle (EV). With an appropriate charging infrastructure, WPT holds great potential to accelerate the acceptance of EVs through users’ higher satisfaction, reducing EV cost, and increasing the driving range and capability. A WPT system based on high-intensity laser power beaming (HILPB) provides an optimal solution for wirelessly charging electric vehicles from a distance of several meters. Despite a large number of WPT approaches, the problem of optimal path configuration for charging EV remains an unexplored area. This paper proposes a method to determine the optimal power transmission path in environments where multiple power transmitters (PTXs) and power receivers (PRXs) are operated simultaneously. To this end, we modeled the HILPB power that reaches a PRX equipped with a photovoltaic (PV) array and validated the model by simulating the WPT process in an environment with multiple PTXs and PRXs using a direct-sequence optical code division multiple access (DS-OCDMA) system. In the simulation environment, upon receiving a request from a PRX, a PTX sent its power channel information through optically encoded laser pulses using each available wireless power channel (WPC). The PRX calculated the maximum deliverable power of a PTX and WPC based on the received channel power indicator of the incident laser beam. Based on the calculation results, it selected the optimal PTX and WPC for its maximum power requirement (MPQ). The MPQ of each PRX was satisfied by applying the algorithm for selecting the PTX according to the alignment and characteristics of the PTXs and PRXs. We modeled a power reception model of the PRX based on a PV array using coded laser pilots and validated it through experimentation. We discussed some algorithms that select the most suitable PTX among several PTXs for which several EVs receive the power it needs.
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Esmaeili, Hossein, Ali Kariminezhad, and Aydin Sezgin. "Robust Transceiver Design for IRS-Assisted Cascaded MIMO Communication Systems." Sensors 22, no. 17 (2022): 6587. http://dx.doi.org/10.3390/s22176587.
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Intelligent reconfigurable surfaces (IRSs) have gained much attention due to their passive behavior that can be a successor to relays in many applications. However, traditional relay systems might still be a perfect choice when reliability and throughput are the main concerns in a communication system. In this work, we use an IRS along with a decode-and-forward relay to provide a possible solution to address one of the main challenges of future wireless networks which is providing reliability. We investigate a robust transceiver design against the residual self-interference (RSI), which maximizes the throughput rate under self-interference channel uncertainty-bound constraints. The yielded problem turns out to be a non-convex optimization problem, where the non-convex objective is optimized over the cone of semidefinite matrices. We propose a novel mathematical method to find a lower bound on the performance of the IRS that can be used as a benchmark. Eventually, we show an important result in which, for the worst-case scenario, IRS can be helpful only if the number of IRS elements are at least as large as the size of the interference channel. Moreover, a novel method based on majorization theory and singular value decomposition (SVD) is proposed to find the best response of the transmitters and relay against worst-case RSI. Furthermore, we propose a multi-level water-filling algorithm to obtain a locally optimal solution iteratively. We show that our algorithm performs better that the state of the art in terms of time complexity as well as robustness. For instance, our numerical results show that the acheivable rate can be increased twofold and almost sixfold, respectively, for the case of small and large antenna array at transceivers.
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Steckenreuter, Andre, Xavier Hoenner, Charlie Huveneers, et al. "Optimising the design of large-scale acoustic telemetry curtains." Marine and Freshwater Research 68, no. 8 (2017): 1403. http://dx.doi.org/10.1071/mf16126.
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Broad-scale acoustic telemetry networks are being established worldwide. The 10-year anniversary of the Integrated Marine Observing System’s Animal Tracking Facility provided the opportunity to assess the efficiency of one of the first national-scale acoustic telemetry networks. Acoustic networks are comprised of acoustic receiver arrays that detect high-frequency transmitters attached to animals that pass within detection range. Herein we assessed the efficiency of eight curtains to detect passing animals by calculating the standardised mean number of detections and transmitters detected at each station. The aim was to determine how many receivers could be decommissioned from each curtain while maintaining its integrity (i.e. detection of all species passing the array). Pivotal locations were defined as the furthest station at which all species would still be detected and where at least 75% of the detections and transmitters would still be detected. By applying these criteria, we were able to improve the cost-effectiveness of our network significantly, reducing the number of stations from 132 to 85 (64% of the original network), yet still retaining 84% of total detections, 86% of transmitters and 100% of detected species. The present study provides a useful framework for refining acoustic telemetry networks.
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Haetrakul, Thanida, Teresa Campbell, Chayanis Daochai, et al. "Assessing the Movements, Habitat Use, and Site Fidelity of the Giant Freshwater Whipray (Urogymnus polylepis) with Acoustic Telemetry in the Maeklong River, Thailand." Water 15, no. 13 (2023): 2311. http://dx.doi.org/10.3390/w15132311.
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We used acoustic telemetry to assess site fidelity, movement patterns, and habitat use within the lower Maeklong River, Thailand, by 22 giant freshwater whipray Urogymnus polylepis. This study is the first of its kind for this rare, endangered species, and it begins to fill critical information gaps about its ecology and life history. Study animals were tagged subcutaneously in the dorsal area with acoustic transmitters and tracked for 12 months using a fixed array of eight receivers. Receivers were positioned within an 18 rkm section of the Maeklong, starting approximately 4 rkm upstream from the mouth. We calculated individual residency indices, tracked longitudinal movements, and assessed annual and seasonal patterns of site use. We also investigated spatial use patterns, diel activity patterns, and relationships of temperature and site fidelity. We detected 86% of our tagged whiprays, 53% of which were detected for the majority of the study period. Whiprays exhibited high site fidelity across seasons. Individuals made long longitudinal movements within the site for much of the study period but seemed to remain closer to the estuary during the second half of the rainy season and early winter. All receivers had large numbers of detections, but upstream receivers were visited for longer time durations than downstream receivers. A receiver in the middle of the study area had the highest detection rate, but low detection durations, suggesting that this receiver is in a migration corridor. A mix of immature and mature males and females was present in the site throughout the study period, suggesting that this area is not exclusively a breeding or nursery site. However, the high site fidelity suggests that this is an important aggregation site for the species. Effective conservation measures may include conservation zones and a shrimp reintroduction program upstream, ensuring fish passage through the middle of the site, and regulating traffic and pollution downstream. We found acoustic telemetry to be an effective study method and encourage its use to improve understanding of the giant freshwater whipray.
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Ferreira, João, João Guerreiro, Rui Dinis, and Paulo Montezuma. "On the Use of Near-Field Constellation Focusing for Physical Layer Security with Extremely Large Antenna Arrays." Electronics 13, no. 5 (2024): 869. http://dx.doi.org/10.3390/electronics13050869.
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In the fast-changing world of wireless communications, the combination of extremely large antenna arrays (ELAAs) and energy-efficient transmission methods is envisioned for the 6G. The application of directivity in the transmitted constellation can increase physical layer security (PLS) and promote the energy efficiency of transmission. In such scenarios, large constellations can be divided into multiple binary phase shift keying (BPSK) components, with each component being individually amplified and transmitted by an antenna. In this work, we consider an ELAA acting as a transmitter and constellation decomposition at the sub-array level. We investigate the impact of considering a near-field channel model in terms of secrecy rate and mutual information. In addition to the energy efficiency of the constellation decomposition, it is demonstrated that the particularities of near-field beamforming increase the PLS, namely in terms of robustness to eavesdropping.
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Domouchtsidis, Stavros, Christos G. Tsinos, Symeon Chatzinotas, and Bjorn Ottersten. "Symbol-Level Precoding for Low Complexity Transmitter Architectures in Large-Scale Antenna Array Systems." IEEE Transactions on Wireless Communications 18, no. 2 (2019): 852–63. http://dx.doi.org/10.1109/twc.2018.2885525.
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Muhleman, Duane O., Bryan J. Butler, Martin A. Slade, and Arie W. Grossman. "Radar Imaging of the Planets Using the Very Large Array." Symposium - International Astronomical Union 158 (1994): 457–68. http://dx.doi.org/10.1017/s0074180900108186.
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We have used the VLA to make images of the planets which are continuously illuminated by the high power planetary radar transmitter on the 70 meter antenna at Goldstone, CA. That instrument is capable of transmitting up to 460,000 watts of continuous power near 8.5 GHz. Radar imaging experiments became possible after the installation of the 8.5 GHz receivers on all VLA antennas by NASA for the encounter of the Voyager spacecraft with Uranus. A similar radar may be configured with the Australia Telescope (array) at Narrabri and the Goldstone 70 m at S-band which may be important for experiments on Venus whose atmosphere strongly absorbs at X-band. Highly successful experiments have been carried out at the VLA on Mercury, Venus, Mars, Saturn's rings and Titan, the giant satellite of Saturn.
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Muhammed, Rashid M., and Gopinath Kaimal Padmam. "A Review on DMSTA Based Channel Estimation Techniques for Wideband Affected Massive MIMO Systems." International Journal of Trend in Scientific Research and Development 4, no. 3 (2020): 587–89. https://doi.org/10.5281/zenodo.3892425.
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Massive multiple input and output MIMO system is currently considered a promising technology to achieve the 5G generation of mobile communication requirements. There is a large no. of antennas used in transmitter and receiver side. The transmitted wideband signal will be sensitive to the propagation delay of electromagnetic wave across the large array aperture, which is called spatial wideband effect. The purpose of this report is to provide a survey of research related to Spatial wide band effect in massive MIMO System and propose suitable channel estimation techniques for mitigation of spatial wide band effect and pilot contamination problem. Muhammed Rashid M | Padmam Gopinath Kaimal "A Review on DMSTA Based Channel Estimation Techniques for Wideband Affected Massive MIMO Systems" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30550.pdf Paper Url :https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/30550/a-review-on-dmsta-based-channel-estimation-techniques-for-wideband-affected-massive-mimo-systems/muhammed-rashid-m
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Кузнецов, А. С., та С. В. Козлов. "ПРИМЕНЕНИЕ ИНФОРМАЦИОННОГО ПОЛЯ ДЛЯ НАВИГАЦИИ ОБЪЕКТОВ". Vestnik of Volga State University of Technology. Series Radio Engineering and Infocommunication Systems, № 3(51) (7 грудня 2021): 31–40. https://doi.org/10.25686/2306-2819.2021.3.31.
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В работе предложен метод навигации объектов в пространстве с позиции теории информационного поля. Приведена классификация объектов информационного поля. Разработаны математический аппарат, а также устройство приёма и обработки сигналов в информационном поле. Создан тестовый стенд исследования информационного поля, с помощью которого экспериментально определены координаты объектов и их отклонения. Introduction. Currently, a lot of the existing radio systems are data transmission systems. At the reception terminal, a mixture of signals is received with various distortions, which are considered as interferences and are compensated. However, these signal distortions contain a large amount of information about the environment where system operates. Using this information, one can get additional data on all the signals and improve the characteristics of radio communication systems. Problem statement. The paper discusses the solution to the problem of developing a test facility operating in the acoustic range within the information field for navigation of mobile passive objects. In this paper, the information field is considered as the field of all physical signals (electrical, acoustic, electromagnetic, optical) that exist in a certain area of space, which contains information about data flows in real time, characteristics of the propagation medium, interactions and locations of objects. To navigate the objects of the information field in the room, a local Cartesian coordinate system and a rangefinder method for determining coordinates were selected. The distance to the object is determined by the delay time of the signal propagation between the objects of the information field, measured by the correlation method. Development of the test facility. There is discussed the development of the test facility. An information field is created in a laboratory with an area of 15 m2by four "own" fixed objects, and the reception and analysis of signals is carried out by "own" fixed passive object. Based on the Virtex5-LX30 field-programmable gate array, which is part of the NI-PXI-7841R module, with the use of the Verilog language, a device for generating, receiving and processing information field signals has been developed. The acoustic signal receivers and transmitters were built with the use of Murata MA40S4S and MA40S4R sensors, respectively. The places of the objects in the laboratory was planned. Analysis of the efficiency of using information field for object navigation was carried out by calculating the delays of the information field signals with the use of a device developed on the basis of Virtex5-LX30, followed by calculating the distance to each active object, the coordinates of the passive object, as well as evaluating their deviations in the Matlab framework. Conclusions. With the use of the developed test facility, the operation of the system was verified and estimated deviations of the coordinates of the passive object did not exceed the theoretically calculated values.
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Cuji, Diego A., Zhengnan Li, and Milica Stojanovic. "Multi-user transmit beamforming for broadband acoustic systems." Journal of the Acoustical Society of America 153, no. 3_supplement (2023): A345. http://dx.doi.org/10.1121/10.0019100.
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Multi-user transmit beamforming for acoustic systems based on orthogonal frequency division multiplexing (OFDM) modulation is studied and demonstrated. Transmit beamforming consists of assigning weight coefficients to multiple transmit elements, such that the signals transmitted from the array add constructively at the users' receive sides. In an optimal setting, the transmitter assigns weights that are proportional to the channel transfer functions to the users. However, the assumption of complete channel knowledge is not entirely accurate, as the transmitter obtains the channels via feedback from the users. Thus, the transmitter has partial knowledge of the channels, as their estimates are not only noisy, but can be outdated if the channels have changed during the time it took to close the feedback loop. These adversities are notably pronounced in time-varying acoustic channels, as the feedback delay is large as compared to the channel coherence time due to the low speed of sound propagation. To counteract this problem, a technique that targets only those features of the channels that can withstand the feedback delay is proposed. Such features are the users' angles of arrival of the principal propagation paths. The principal paths are stable paths that do not experience rapid fluctuations and are thus varying sufficiently slowly that they can tolerate long feedback delays. The design concepts are demonstrated using experimental over-the-air transmissions in an indoor environment of an acoustic communications testbed.
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Scholl, Carsten, and R. Nigel Edwards. "Marine downhole to seafloor dipole-dipole electromagnetic methods and the resolution of resistive targets." GEOPHYSICS 72, no. 2 (2007): WA39—WA49. http://dx.doi.org/10.1190/1.2434775.
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Most active marine electromagnetic surveys use an array of transmitting and receiving electric dipoles located on the sea-floor. There are many reports of successful detections of buried resistors with these arrays. Nevertheless, the concept has a significant drawback: Large offsets between the transmitter and receiver with respect to the target depth are needed. A logical alternative is the use of a vertical electric-dipole transmitter in a borehole deeper than the target, combined with receivers located at the seafloor. Because current must pass through the target, even data recorded at short offsets with respect to target depth should be sensitive to the target. We derived the equations for the electric and magnetic field components produced by the vertical electric dipole in a 1D layered medium. The equations are used to model the fields for resistive layers. An eigenparameter analysisis applied to the different field components, and the resolution is compared with the standard seafloor inline array. The analyses show that data for the downhole transmitter are more sensitive to the resistance between the source and the receiver than the sea-floor array. However, model geometry such as depth to the target is resolved less easily. The resolution of the model geometry is improved significantly when a long bipole transmitter is used, extended from below the target layer to a level above it. We carried out 3D modeling for the downhole transmitter through the use of a finite-difference algorithm. Results indicate that these data are very sensitive to lateral changes within the target layer. Differences between electric fields simulated at the seafloor for 3D models and a reference model show a correlation to lateral resistivity differences. This finding suggests that the array is suitable for mapping and monitoring resistivity anomalies outward from the borehole.
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Yu, Lei, Pengfei Ma, Guangzhen Luo, et al. "Adoption of large aperture chirped grating antennas in optical phase array for long distance ranging." Optics Express 30, no. 15 (2022): 28112. http://dx.doi.org/10.1364/oe.464358.
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Optical phased array can be widely used in many fields benefiting from its superior performance. We designed and fabricated chirped grating antennas and uniform grating antennas for the optical phased array. The effective aperture of the chirped grating antennas is about twice that of the uniform grating antennas. The chirped grating optical phased array can receive the reflected signal of the object at a distance of 100 m, while the uniform grating optical phased array can only receive 50 m under the same conditions. Additionally, a ranging distance of 25 m is achieved when two chirped grating optical phased arrays are set as the transmitter and receiver.
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Fu, Tao, Yi Wang, Lei Qiu, and Xin Tian. "Sector Piezoelectric Sensor Array Transmitter Beamforming MUSIC Algorithm Based Structure Damage Imaging Method." Sensors 20, no. 5 (2020): 1265. http://dx.doi.org/10.3390/s20051265.
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Elastic-wave-based structural health monitoring technology has a broad application potential for its sensitivity and ability to achieve regional monitoring. For structures with large damping and specific shapes, the traditional damage monitoring method is limited by the sensor arrangement area and affected by low signal-to-noise ratios, so it is difficult to accurately locate the damage in a structure. To solve this problem, this paper proposed a damage monitoring method based on a sector piezoelectric sensor array for multiple signal classification algorithm. By arranging two sector piezoelectric sensor arrays that are suitable for a specific structure, the damage scattering array signal under the multi-excitation source was obtained and synthesized, the signal-to-noise ratios were improved, and the damage location accuracy was thus improved. The effectiveness of the method was verified by monitoring the damage in a circular bonded structure with a metal ring. Compared with the damage localization methods based on the traditional single excitation source multiple signal classification algorithm, path imaging and delay-sum imaging, this method can achieve better damage location and has a higher localization accuracy.
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Liu, Hui, Qing Xu, Guowang Jin, and Hongmin Zhang. "MIMO Antenna Polynomial Weighted Average Design Method of Downward-Looking Array SAR." International Journal of Antennas and Propagation 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/3029847.
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MIMO antenna polynomial weighted average design method of downward-looking array SAR was proposed from the angle of surveying and mapping in this paper, in order to solve the ill-posed problem that an equivalent virtual array can be implemented by a variety of physical transmitter-receiver arrays for bistatic MIMO linear array. For wave band, resolution, elevation precision, and working height concerned by the applications of surveying and mapping, the length of equivalent virtual array and actual physical array meeting the needs of large scale topographical mapping was solved. Then array numbers and position vectors of MIMO downward-looking array SAR of real aerial mapping platform were optimized. According to this design, some simulation experiments and comparisons were processed. The results proved the rationality and effectiveness of this array configuration by comparing the differences of 3D imaging results and the original simulation scene, counting mean and standard deviation of elevation reconstruction error eliminating the influence of shadow areas, and counting the probability of elevation reconstruction error within half a resolution of the whole scene and individual building area.
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Dong, Zheng, He Chen, and Jian-Kang Zhang. "Design of Multi-User Noncoherent Massive SIMO Systems for Scalable URLLC." Entropy 25, no. 9 (2023): 1325. http://dx.doi.org/10.3390/e25091325.
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This paper develops and optimizes a non-orthogonal and noncoherent multi-user massive single-input multiple-output (SIMO) framework, with the objective of enabling scalable ultra-reliable low-latency communications (sURLLC) in Beyond-5G (B5G)/6G wireless communication systems. In this framework, the huge diversity gain associated with the large-scale antenna array in the massive SIMO system is leveraged to ensure ultra-high reliability. To reduce the overhead and latency induced by the channel estimation process, we advocate for the noncoherent communication technique, which does not need the knowledge of instantaneous channel state information (CSI) but only relies on large-scale fading coefficients for message decoding. To boost the scalability of noncoherent massive SIMO systems, we enable the non-orthogonal channel access of multiple users by devising a new differential modulation scheme to ensure that each transmitted signal matrix can be uniquely determined in the noise-free case and be reliably estimated in noisy cases when the antenna array size is scaled up. The key idea is to make the transmitted signals from multiple geographically separated users be superimposed properly over the air, such that when the sum signal is correctly detected, the signal sent by each individual user can be uniquely determined. To further enhance the average error performance when the array antenna number is large, we propose a max–min Kullback–Leibler (KL) divergence-based design by jointly optimizing the transmitted powers of all users and the sub-constellation assignments among them. The simulation results show that the proposed design significantly outperforms the existing max–min Euclidean distance-based counterpart in terms of error performance. Moreover, our proposed approach also has a better error performance compared to the conventional coherent zero-forcing (ZF) receiver with orthogonal channel training, particularly for cell-edge users.
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Zhen tao, Zhang, Li Gang, Zou Ping guo, Li Qiang, and Chen Ya bin. "Research and Application of Power Detection Technology on Photovoltaic Module Array." E3S Web of Conferences 165 (2020): 01020. http://dx.doi.org/10.1051/e3sconf/202016501020.
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Based on the principle of photovoltaic module power detection, an intelligent module array power detection scheme is proposed, and a photovoltaic module array power detection device is designed. It consists of a master and multiple slaves. The voltage, current, temperature, and irradiation signals are synchronously collected and processed by acquisition module CC2530, and then wirelessly transmitted to the host for processing through zigbee communication protocol. These signals are calculated and displayed by the host software. Photovoltaic module array power detection device adopts modular design and experience experimental test. The measurement error meets the needs of field test. The device has the advantages of convenient portability, simple operation, high informatization, large test range, and good safety.
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Xiong, Chunbao, and Hongzhi Bai. "Calibration of Large-Scale Spatial Positioning Systems Based on Photoelectric Scanning Angle Measurements and Spatial Resection in Conjunction with an External Receiver Array." Applied Sciences 10, no. 3 (2020): 925. http://dx.doi.org/10.3390/app10030925.
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Positioning systems providing high-precision real-time measurements over very large spatial scales are urgently required for large-scale industrial manufacturing applications. While large-scale positioning systems (LSPSs) employing laser transmitter stations have been employed in engineering practice, the introduction of an LSPS into an existing industrial manufacturing setting must first solve the problems of docking with existing control points and external parameter calibration. However, calibrating the external parameters of a measurement system is very difficult under extreme and complicated working conditions due to the limited visibility of transmitter stations and the measurement distances involved. This problem is addressed in this paper by proposing a single transmitter station calibration method based on a photoelectric scanning multi-angle resection positioning model that combines photoelectric scanning angle measurements and spatial resection in conjunction with an external receiver array. Positioning information is obtained by solving the unknown parameters of the model according to a nonlinear optimization approach using the Levenberg–Marquardt least-squares fitting algorithm. The feasibility and spatial positioning accuracy of the proposed method are verified experimentally. The experimental results demonstrate that the principles of the proposed method are correct, and the method can achieve millimeter measurement accuracy, which meets the requirements of measurement tasks in engineering applications.
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Velichko, A., and A. J. Croxford. "Strategies for data acquisition using ultrasonic phased arrays." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2218 (2018): 20180451. http://dx.doi.org/10.1098/rspa.2018.0451.
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Ultrasonic phased arrays have produced major benefits in a range of fields, from medical imaging to non-destructive evaluation. The maximum information, which can be measured by an array, corresponds to the Full Matrix Capture (FMC) data acquisition technique and contains all possible combinations of transmitter–receiver signals. However, this method is not fast enough for some applications and can result in a very large volume of data. In this paper, the problem of optimal array data acquisition strategy is considered, that is, how to make the minimum number of array measurements without loss of information. The main result is that under the single scattering assumption the FMC dataset has a specific sparse structure, and this property can be used to design an optimal data acquisition method. An analytical relationship between the minimum number of array firings, maximum steering angle and signal-to-noise ratio is derived, and validated experimentally. An important conclusion is that the optimal number of emissions decreases when the angular aperture of the array increases. It is also shown that plane wave imaging data are equivalent to the FMC dataset, but requires up to an order of magnitude fewer array firings.
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Esttaifan, Bashar Adel, Oday AbdulLateef, and Waleed Ameen Mahmoud. "Design and Implementation of a Multiplier free FPGA based OFDM Transmitter." Journal of Engineering 19, no. 08 (2023): 1056–72. http://dx.doi.org/10.31026/j.eng.2013.08.10.
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Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multi-carrier technique.The core operation in the OFDM systems is the FFT/IFFT unit that requires a large amount of hardware resources and processing delay. The developments in implementation techniques likes Field Programmable Gate Array (FPGA) technologies have made OFDM a feasible option. The goal of this paper is to design and implement an OFDM transmitter based on Altera FPGA using Quartus software. The proposed transmitter is carried out to simplify the Fourier transform calculation by using decoder instead of multipliers. After programming ALTERA DE2 FPGA kit with implemented project, several practical tests have been done starting from monitoring all the results of the implemented blocks (VHDL code) and compare them with corresponding results from simulation system implemented in matlab 2010a. The results of these practical tests show that the suggested approach gives a significant improvement in reducing complexity and processing delays (45 nsec) in comparison with the conventional implementations of OFDM transmitter.
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Ng, C., L. Rizk, C. Mannion, and E. F. Keane. "Search for Extraterrestrial Intelligence with the ngVLA." Astronomical Journal 164, no. 5 (2022): 205. http://dx.doi.org/10.3847/1538-3881/ac92e7.
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Abstract The next generation Very Large Array (ngVLA) will be the premiere centimeter-wave radio array in the Northern Hemisphere by the mid 2030s and thus has the potential to be one of the most effective instruments for the search for extraterrestrial intelligence (SETI). We show that, as of now, the ngVLA will be the only facility capable of detecting an extraterrestrial intelligence (ETI) signal generated by an Arecibo-like transmitter further than 300 pc. We present the optimal antenna array configurations and study the proposed frequency band coverage of the ngVLA and its implications to SETI. We argue for the ability to form of the order of 64 commensal high spectral resolution beams, as the large number of line of sights is critical to provide a competitive survey speed when compared to other modern surveys with telescopes such as MeerKAT and the future SKA. We advocate an Ethernet-based telescope architecture design for the ngVLA, which will provide a high degree of flexibility in SETI data analysis and will benefit the wider astronomy community through commensal science and open-source code, maximizing the potential scientific output of the ngVLA.
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Xi, Yanpeng, Jian Liu, and Wenhao Zhao. "SATCOM Earth Station Arrays Anti-Jamming Based on MVDR Algorithm." Applied Sciences 13, no. 14 (2023): 8337. http://dx.doi.org/10.3390/app13148337.
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In modern life, a large amount of information is transmitted through satellites. The anti-jamming ability of satellite communication earth stations is the basis for ensuring the smooth flow of information. In the case that multiple small earth stations cannot communicate due to jamming, the minimum variance distortionless response (MVDR) algorithm based on reflector antenna array is proposed. Firstly, the gain expression of satellite communication earth station antenna is derived, and the mathematical model of the received signal of the reflector antenna array is established. Then, the MVDR beamforming algorithm based on the reflector antenna is proposed and applied to the satellite communication earth station reflector antenna array, and the anti-jamming capability of the reflector antenna array using this algorithm is analyzed through simulation. The simulation results show that the earth station reflector antenna array using MVDR algorithm can effectively achieve array gain of the direction of the satellite signal, suppress the jamming signals, increase the output signal to interference plus noise ratio (SINR) of the reflector antenna array, and increase the output signal to jamming plus noise ratio with the increase in the number of snapshots.
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Ifeoma, B. Asianuba. "Side Lobe Reduction in Linear Array Antenna using Numerical Computation Approach." European Journal of Advances in Engineering and Technology 6, no. 4 (2019): 29–35. https://doi.org/10.5281/zenodo.10687581.
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<strong>ABSTRACT</strong> Large amount of energy is saved when a transmitting antenna propagates its field radiations painstakingly in the required direction of propagation. For this reason, reduction in side lobe radiation is essential to avoid degrading the total power and efficiency of the radiating structure. In this paper, a numerical approach is adopted other than the well known stochastic approach to reduce side lobe radiations in linear array antennas. This choice is as a result of the short design cycle of the numerical solution for antenna field problems, full exploration of design space and provision of large physical insights on the design output. The parameters of the array antenna are deployed in the reduction of the side lobe radiations. These include; non-uniform inter-element spacing, non-uniform excitation amplitude and varying number of antenna elements. Radiation patterns for linear array antenna with non-uniform characteristics are generated from the simulation result. The patterns with the least side lobe and beam width are determined. This outcome ensures signals are not transmitted in undesirable directions and efficient communication process can be guaranteed.
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Xu, Hui, Kaixue Ma, Shuantao Li, and Gaojian Liu. "A Space-Borne Ka-Band Tile-Type Phased Array Transmitter Module Based on HTCC Technology." Applied Sciences 14, no. 24 (2024): 11992. https://doi.org/10.3390/app142411992.
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We propose a double-sided layout design method with high reliability for multi-beam phased array transmitter modules based on high-temperature co-fired ceramic technology. Efficient transmission of microwave signals and low-frequency signals is realized by using multi-layer wiring and an inter-layer transition. The proposed Ka-band transmitter module exhibits a gain of ≥26 dB, an output power of ≥21 dBm, and an overall efficiency of the component of ≥40%. The RMS accuracy of phase shift and attenuation is better than 3° and 0.5 dB, respectively. The proposed design method addresses the problems of high integration, lightness, and miniaturization in transmit/receive module design, and shows a good performance of heat dissipation performance and sealing capability. It can be easily expanded to large-scale phased arrays.
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Rajagopalan, Jagannathan, Krishnan Balasubramaniam, and C. V. Krishnamurthy. "A single transmitter multi-receiver (STMR) PZT array for guided ultrasonic wave based structural health monitoring of large isotropic plate structures." Smart Materials and Structures 15, no. 5 (2006): 1190–96. http://dx.doi.org/10.1088/0964-1726/15/5/005.
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Lei, Yufang, Lingxuan Zhang, Zhiyuan Yu, Yulong Xue, Yangming Ren, and Xiaochen Sun. "Si Photonics FMCW LiDAR Chip with Solid-State Beam Steering by Interleaved Coaxial Optical Phased Array." Micromachines 14, no. 5 (2023): 1001. http://dx.doi.org/10.3390/mi14051001.
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LiDAR has attracted increasing attention because of its strong anti-interference ability and high resolution. Traditional LiDAR systems rely on discrete components and face the challenges of high cost, large volume, and complex construction. Photonic integration technology can solve these problems and achieve high integration, compact dimension, and low-cost on-chip LiDAR solutions. A solid-state frequency-modulated continuous-wave LiDAR based on a silicon photonic chip is proposed and demonstrated. Two sets of optical phased array antennas are integrated on an optical chip to form a transmitter–receiver interleaved coaxial all-solid-state coherent optical system which provides high power efficiency, in principle, compared with a coaxial optical system using a 2 × 2 beam splitter. The solid-state scanning on the chip is realized by optical phased array without a mechanical structure. A 32-channel transmitter–receiver interleaved coaxial all-solid-state FMCW LiDAR chip design is demonstrated. The measured beam width is 0.4° × 0.8°, and the grating lobe suppression ratio is 6 dB. Preliminary FMCW ranging of multiple targets scanned by OPA was performed. The photonic integrated chip is fabricated on a CMOS-compatible silicon photonics platform, providing a steady path to the commercialization of low-cost on-chip solid-state FMCW LiDAR.
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Goldman, Mark, Eldad Levi, Buelent Tezkan, and Pritam Yogeshwar. "The 2D coastal effect on marine time domain electromagnetic measurements using broadside dBz/dt of an electrical transmitter dipole." GEOPHYSICS 76, no. 2 (2011): F101—F109. http://dx.doi.org/10.1190/1.3525276.
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Galvanic transmitter-receiver arrays commonly are used in marine controlled-source electromagnetic (CSEM) exploration of electrically resistive targets such as hydrocarbons, gas hydrates, etc. These arrays utilize vertical electric currents and, as a result, are expected to provide better resolving capability for exploring subhorizontal resistive structures than arrays including horizontal coils. If, however, a subseafloor resistive target is located within a transition zone at distances of up to a few kilometers from the shoreline, the 2D sea-coast resistivity contrast significantly affects the resolving capability of the measurements. An extensive multidimensional modeling supported by numerous offshore measurements showed that the inductive array consisting of a horizontal electric dipole transmitter and a broadside vertical magnetic dipole (horizontal coil) receiver exhibits much better resolving power in time domain compared to all other arrays but those with a vertical electric dipole. This effect takes place only if a short offset receiver coil is located between the transmitter dipole and the coast. If the coil is located at the seaside of the transmitter dipole, the signal lacks the resolving capability almost entirely. At large offsets, the resolving capability of the measurements is relatively low at both sides of the transmitter dipole. Although actual field measurements were conducted only to explore a shallow target (fresh subseafloor groundwater body), calculations show that the same phenomenon exists in case of deep targets (e.g., hydrocarbons).
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Peña-Martín, Juan P., and Juan M. Romero-Jerez. "An Analytical Study of the Impact of Arbitrary Receive Antenna Correlation in TAS/MRC." International Journal of Antennas and Propagation 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/798015.
Full textAbstract:
Novel closed-form expressions are derived for the performance analysis of a multiple-input multiple-output (MIMO) system in Rayleigh fading using transmit antenna selection (TAS) at the transmitter and maximal ratio combining (MRC) at the receiver. Receive antennas are assumed to be arbitrarily correlated, as no restriction is imposed on the correlation matrix. General exact and asymptotic expressions to evaluate the bit error rate (BER) of different modulation schemes are presented for uncoded transmission, and a closed-form expression is presented for the channel capacity. It is demonstrated that channel capacity may improve due to correlation at the receive antennas if the transmit array size is large enough as a result of a higher signal variability and the antenna selection performed at the transmitter. Monte Carlo simulations have been carried out to validate the analysis, showing an excellent agreement with the theoretical results.
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Kim, Ho Yeol, Youngseok Lee, and Sangwook Nam. "Efficiency Bound Estimation for a Practical Microwave and mmWave Wireless Power Transfer System Design." Journal of Electromagnetic Engineering and Science 23, no. 1 (2023): 69–74. http://dx.doi.org/10.26866/jees.2023.1.r.146.
Full textAbstract:
In this study, we present an efficient method to find the power transfer efficiency (PTE) bound for practical microwave and mmWave wireless power transfer (MPT) systems composed of transmitter (Tx) and receiver (Rx) array antennas. The PTE bound of the MPT system is obtained by formulating it as a convex optimization problem (CVP) that maximizes the power received at the Rx array under the transmit power constraint. The channel state information (CSI) between each element of the Tx and the Rx is the input parameter of the proposed CVP. The CSI is estimated using the Friis transmission equation and the active element pattern of the array antenna because the Tx and the Rx are assumed to be large arrays. For an MPT system designed at 10 GHz and 24 GHz, the estimated PTE bound is compared to those in previous studies while varying the distance and tilted angle between the Tx and the Rx. The computation times required for the methods are compared. The numerical results show that the proposed method provides a faster and more accurate PTE bound without full electromagnetic simulation of the MPT system consisting of Tx and Rx array antennas. This study's results will serve as guidelines for practical MPT system design in the future.
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Zhang, Jie, Pengfei Wu, Qinghu Han, Xin Wei, and Yi Duan. "Dynamic Behavior of Satellite and Its Solar Arrays Subject to Large-Scale Antenna Deployment Shock." Aerospace 11, no. 5 (2024): 349. http://dx.doi.org/10.3390/aerospace11050349.
Full textAbstract:
Satellites should be equipped with more and more deployable, large, flexible appendages to improve their service efficiency and reduce launch costs. The spring-driven deployment method of flexible appendages has been widely applied and generates great instantaneous shock loads on satellites, maybe affecting the safety of other flexible appendages, but the current related investigations for satellites with multiple large flexible appendages are insufficient. In this study, the deployment test of the antenna itself was conducted, and the attitude changes in a satellite during antenna deployment were telemetered. Then, a related dynamical model of the satellite was established and verified by the telemetry values of the satellite. Finally, the shock mechanism transmitted to solar arrays was analyzed, and the effect of solar array attitude was discussed. The results show that the simulated method of antenna deployment equivalent to the shock loads tested was thought to be efficient, though it could cause a small non-zero constant of the simulated angular velocities in the antenna deployment direction. The shock-induced moments, except the rotation direction of the solar array drive assembly (SADA), should be highlighted for the antenna deployment dynamic design of satellites, and the solar array attitude has few effects on the shock-induced loads at the SADA.
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Boopalan, Navaamsini, Agileswari K. Ramasamy, and Farrukh Nagi. "A Comparison of Faulty Antenna Detection Methodologies in Planar Array." Applied Sciences 13, no. 6 (2023): 3695. http://dx.doi.org/10.3390/app13063695.
Full textAbstract:
Broadcasting, radar, sonar and space telecommunication systems use phased arrays to produce directed signals to be transmitted at the desired angle. This system requires a large number of antenna elements. The presence of faulty element(s) in an array causes asymmetry, which results in a deformed radiation pattern with higher sidelobe levels. Higher sidelobe levels indicate waste of energy by transmitting and receiving signals in unwanted directions. Hence, it is important to develop a method that detects faulty elements and corrects the radiation pattern. To correct the failed radiation pattern, failed elements in an array must be identified first. There have been various studies conducted on linear array failed radiation pattern correction and the finding of faulty elements, but investigation on the planar array is limited. Further, the optimization suggested for linear arrays does not necessarily work for the planar array. In this study, planar array faulty antenna detection was developed with pattern search (PS), simulated annealing (SA), and particle swarm optimization (PSO) methods by reducing the Signal to Noise Ratio (SNR) as the objective function. The analysis was varied for 8 × 8 and 6 × 6 planar arrays with different types of failures. The results were compared to find the best method to identify the faulty element’s location in a planar array. The pattern search method produced outstanding results in finding the faulty element’s locations by providing 100% accuracy for all types of failure, while other methods failed to do the same.
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Ferreira, Ricardo Coelho, Michelle S. P. Facina, Felipe A. P. de Figueiredo, Gustavo Fraidenraich, and Eduardo Rodrigues de Lima. "Secrecy Analysis and Error Probability of LIS-Aided Communication Systems under Nakagami-m Fading." Entropy 23, no. 10 (2021): 1284. http://dx.doi.org/10.3390/e23101284.
Full textAbstract:
Large intelligent surfaces (LIS) are a new trend to achieve higher spectral efficiency and signal-to-noise ratio in mobile communications. For this reason, this paper proposes metrics to analyze the performance of systems with multiple antennas aided by LIS and derive the spectral efficiency, secrecy outage probability, and bit error probability in an environment with Nakagami-m distributed fading. In addition to an eavesdropper, there is a single-antenna user, an array of antennas at the transmitter side and the possibility of a direct link between transmitter and receiver. This study assumes that the LIS performs non-ideal phase cancellation leading to a residual phase error that follows a Von Mises distribution, and shows that the resulting channel can be accurately approximated by a Gamma distributed SNR whose parameters are analytically derived. From these formulas, it is possible to evaluate the effect of the strength of the line-of-sight link by varying the Nakagami parameter, m.