Individual Transmitters Research Articles

A novel unified interference management scheme for multicellular MIMO communication with instantaneous relay

SummaryIn the world of emerging wireless networks, interference poses a significant challenge to reliable wireless communication. Additionally, these networks are prone to path loss and blockages, which can be addressed by utilizing the advanced technology of multihop communication with instantaneous relay (IR). However, scenarios involving IR‐assisted networks are considered instances of multihop communications that face potential obstacles caused by interference. As a result, multiple interference management approaches exist to tackle this interference issue, among which aligned interference neutralization (AIN) is a state‐of‐the‐art technology that seamlessly unifies two established interference management strategies: interference alignment (IA) and interference neutralization (IN). Therefore, this paper presents a novel tristaged AIN scheme to mitigate interference in a multicellular multiple‐input multiple‐output (MIMO) interference multiple access channel (IMAC). In the proposed scheme, the initial stage‐1 involves transmitting message signals from individual transmitters or users to the IR and the receiving base stations (BSs). In stage‐2, the IR neutralizes half of the interference signals by performing IN. Finally, in stage‐3, IA is carried out at the receiver BS terminals, aligning the remaining interference signals equally within the available dimensions. Based on this proposed approach, we determined that for an IR‐aided multicellular MIMO IMAC, the achievable degree of freedom (DoF) is 2N. The proposed approach's robustness and effectiveness have been analyzed through extensive simulations, and these simulation results indicated that the proposed approach outperforms other benchmark interference management techniques in terms of DoF and sum rate, thereby improving user performance.

Design and Performance Investigation of a Temperature Compensated Transmitter With GaN HEMTs for Phased-Array Applications

This article presents a temperature compensated transmitter for phased-array applications. The high-temperature effects on each individual transmitter building block are studied and compensated to mitigate the performance variations. Furthermore, a new active, tunable, and variable gain phase shifter VGPS) architecture is proposed, which features low-performance variation with temperature and high gain without compromising the phase shift range. A temperature sensor is designed to adaptively adjust the critical dc bias voltages to minimize the variation of the active devices. A class- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{F}^{-1}$ </tex-math></inline-formula> power amplifier PA) is designed, as the last stage in the transmitter chain, and its performance variation is compensated through the VGPS stage by adaptively tuning its characteristics. Gallium-nitride (GaN)-on-silicon-carbide (SiC) high-electron-mobility transistors (HEMTs) are adopted as the active devices and a voltage-controlled capacitor (varactor) used in the VGPS stage. The transmitter is prototyped on a piece of Rogers 4003C substrate, and the system performance is measured. The transmitter has the minimum and the maximum small-signal gain of 5.2 and 31.5 dB, respectively, with the maximum variation of < 2.3 dB across the temperature range and the frequency range of 2–2.1 GHz. The insertion phase variation also remains below 6.5° across the phase shift, temperature, and frequency range. The maximum output power and power added efficiency (PAE) are measured to be 33 dBm and 58%, respectively, at the maximum ambient temperature of 220 °C. The measurement results also show that the transmitter is able to transmit 64-QAM signals with the data rate of 120 Mb/s at the maximum ambient temperature of 220 °C.

Specific emitter identification for IoT devices based on deep residual shrinkage networks

Specific emitter identification can distinguish individual transmitters by analyzing received signals and extracting inherent features of hard-ware circuits. Feature extraction is a key part of traditional machine learning-based methods, but manual extraction is generally limited by prior professional knowledge. At the same time, it has been noted that the performance of most specific emitter identification methods degrades in the low signal-to-noise ratio (SNR) environments. The deep residual shrinkage network (DRSN) is proposed for specific emitter identification, particularly in the low SNRs. The soft threshold can preserve more key features for the improvement of performance, and an identity shortcut can speed up the training process. We collect signals via the receiver to create a dataset in the actual environments. The DRSN is trained to automatically extract features and implement the classification of transmitters. Experimental results show that DRSN obtains the best accuracy under different SNRs and has less running time, which demonstrates the effectiveness of DRSN in identifying specific emitters.

An Assessment of CyGNSS v3.0 Level 1 Observables over the Ocean

Global Navigation Satellite System Reflectometry (GNSS-R) is a rapidly developing Earth observation technology that makes use of signals of opportunity from Global Navigation Satellite Systems that have been reflected off the Earth’s surface. The Cyclone Global Navigation Satellite System (CyGNSS) is a constellation of eight small satellites launched by NASA in 2016, carrying dedicated GNSS-R payloads to measure ocean surface wind speed at low latitudes (±35° North/South). The ESA ECOLOGY project evaluated CyGNSS v3.0 products, which were recently released following various calibration updates. This paper examines the performance of the new calibration by evaluating CyGNSS v3.0 Level-1 Normalised Bistatic Radar Cross Section (NBRCS) and Leading Edge Slope (LES) data from individual CyGNSS units and different GPS transmitters under constant ocean wind conditions. Results indicate that L1 NBRCS from individual CyGNSS units are well inter-calibrated and remarkably stable over time, a significant improvement over previous versions of the products. However, prominent geographical biases reaching over 3 dB are found in NBRCS, linked to factors including the choice of GPS transmitter and the bistatic geometry. L1 LES shows similar anomalies as well as a secondary geographical pattern of biases. These findings provide a basis for further improvement of CyGNSS Level-2 wind products and have wider applicability to improving the calibration of GNSS-R sensors for the remote sensing of non-ocean Earth surfaces.

A Trellis-Coded Quantization Approach to Transmitting Correlated Gaussian Sources Over a Fading MAC Without Transmitter-CSI

It is known that source-channel separation is sub-optimal for communicating correlated Gaussian sources over a Gaussian multiple access channel (GMAC). Considering a two-to-one GMAC which undergoes Rayleigh block-fading, we present a novel approach to practical joint source-channel coding for the scenario in which the common receiver has instantaneous CSI but only the CSI distribution is available to the individual transmitters. This approach, referred to as source-channel trellis-coded vector quantization (SC-TCVQ), simply relies on using TCVQs as fixed-rate source-channel encoders. One key issue is the optimization of the TCVQ codebooks to the mean channel signal-to-noise ratio (CSNR), and to this end, we present an analytical method to obtain the rates required for codebook design. Another key issue is the joint estimation of the sources at the receiver, for which we present a detector-estimator based on the Cartesian product of the two encoder-trellises. Simulation results show that the proposed SC-TCVQ codes, in some cases, can even beat the asymptotic performance bound for a separate source-channel code consisting of a distributed vector quantizer and capacity achieving channel codes. SC-TCVQ appears to be the best known practical code design to date for the given communication problem.

Analysis of Received Power in RF Wireless Power Transfer System With Array Antennas

In this paper, a method for calculating the received power in a radio-frequency wireless power transfer system with array antennas is proposed. The received power is derived based on the superposition of the electric fields that radiate from individual transmitter (Tx) elements and are captured by each receiver (Rx) element. That is expressed in a finite series form with the radiation patterns of an element considering mutual coupling in the array and corresponding distances between the elements of Tx and Rx. Unlike conventional methods (such as the Friis and Goubau formulas), this approach is able to calculate the received power precisely in both Fresnel and far-field regions. It is also efficiently applicable to various cases, such as those involving beamforming and with varying positions of Rx. The calculated results using this method are applied to a 5.2 GHz WPT system with array antennas and verified through comparisons with both simulation and experimental results.

5G mmW Link Range Uncertainties From RF System Calculations and OTA Measurements

Phased arrays in 5G millimeter wave (mmW) communication are used at both link ends to separate users and to enhance the link range. The radio hardware’s RF performance metrics vary due to part-to-part variations within component tolerances. In this paper, we derive probability density functions (PDFs) of over-the-air (OTA) transmission (TX) powers for individual transmitter (Tx) paths and total TX power of the 5G mmW array using Monte Carlo simulations based on component tolerances. The PDF of the TX power individual path of the array follows a log-normal distribution on a linear scale. Hence, the total array’s OTA TX power is a sum of independent linear scale log-normal powers when the power combination happens in OTA towards the main beam direction. We show that the Tx array’s mean power increases when multiple log-normally variated individual TX powers are summed together. Additionally, we prove that a link budget maps to a link range in a non-linear way, skewing the normally distributed link budget to a log-normally distributed link range. The link ranges based on RF system parameter analysis, RF system calculation, and OTA measured system error vector magnitude (EVM) based link range estimation had an excellent match when a 16-QAM 5G NR signal was used. The calculated link ranges are 410 and 434 meters, while the OTA measured system EVM measurement-based link range is 415 meters. For example, uncalibrated Tx array paths would increase the mean of the array’s TX power by 1.2 dB, and the link range increases from 415 to 498 meters, but simultaneously the standard deviation increases from 26 to 51 meters.

PERFORMANCE ANALYSIS OF RESOURCE ALLOCATION TECHNIQUES FOR POWER CONTROL IN DEVICE-TO-DEVICE CELLULAR SYSTEMS

Recent development in pairs of devices communications in the cellular system has necessitated the emergence of various resource allocation strategies for power control with the hope of achieving higher data rate, enhanced system capacity and overall spectral efficiency. Strategies for efficient service delivery in device-to-device (D2D) cellular system have often posed daunting challenges requiring uncompromising techniques. In this work, various techniques for resource allocation strategies for power control in D2D cellular system are investigated. This work is dedicated at the best technique of achieving maximum transmission power of users of cellular and the device pair users with reference to the efficient service delivery coupled with established signal-to-interference-plus-noise ratio (SINR) at the base station and the D2D users across the channel of the uplink because of the ability of the individual transmitter of devices have been able to realign with the power of transmitter relative to the calculated SINR and interference parameters. An expression of SINR, D2D pairs and the distance between device pairs with respect to base station for the optimized network for the various techniques are analyzed. The performance of the resource-based power control technique (RPCT) and the adaptive power control technique (APCT), with respect to the SINR and the device pairs, has shown effectiveness in its ability to address over forty-three pairs of D2D in order to have an improved level of SINR as obtained in this work, it is convenient to say that an increase in the number of cellular users, enables a corresponding increase in the total capacity of D2D users. When an increase is experienced in the number of users of cellular, it automatically adds a value of increase to the reusable channels thereby enabling additional quantity of D2D users in the clusters, such that co-channel interference within the D2D users in the neighboring cluster reduces, thereby enabling an increased capacity of the user of D2D.

Transmitter Identification Signal Detection Algorithm for ATSC 3.0 Single Frequency Networks

To effectively operate and maintain an existing single frequency network (SFN), the advanced television systems committee (ATSC) 3.0 transmission system has utilized a transmitter identification (TxID) technique. The TxID technique aims is to obtain the channel impulse response (CIR) of each transmitter independently to support the adjustment of the relative power level and delay offset of individual transmitters. The professional receiver can detect such CIR, but a commercial ATSC 3.0 receiver does not need to be necessarily decoded the TxID signal. Also, according to the ATSC 3.0 standard, the TxID signal is embedded into the preamble signal with an appropriately low injection level (IL), such that the impact on the preamble reception is negligible. This paper proposes an efficient TxID signal detection algorithm to enhance the individual CIR detection performance during the TxID analyzing process. The simulation results indicate that the proposed TxID signal detection algorithm can offer better individual CIR detection performance as compared to the conventional TxID signal detection algorithms, even though the IL of TxID signal is low.

Tracking Performance in LoRaWAN-Like Systems and Equivalence of a Class of Distributed Learning Algorithms

Considering a low power wide area random access system (like LoRaWAN) where the individual transmitters are mobile, we 1) propose a way of quantifying the performance of tracking of the mobile devices, and 2) design a distributed algorithm to achieve a target tracking performance. The insights gained are then used to provide an analysis of a family of target-achieving reinforcement-learning algorithms used in the literature to learn the optimal (Nash Equilibrium) random access probabilities. By mapping the payoff function in the equivalent game to the performance metric, we establish that, under some general conditions of inter-node parameter separability, the algorithm convergence is independent of the payoff function used. The mapping from the desired performance metric to the success probability in random access can be used in the algorithm to achieve a target success probability.

Simultaneous Quantification of Vesicle Size and Catecholamine Content by Resistive Pulses in Nanopores and Vesicle Impact Electrochemical Cytometry.

We have developed the means to simultaneously measure the physical size and count catecholamine molecules in individual nanometer transmitter vesicles. This is done by combining resistive pulse (RP) measurements in a nanopore pipet and vesicle impact electrochemical cytometry (VIEC) at an electrode as the vesicle exits the nanopore. Analysis of freshly isolated bovine adrenal vesicles shows that the size and internal catecholamine concentration of vesicles varies with the occurrence of a dense core inside the vesicles. These results might benefit the understanding about the vesicles maturation, especially involving the “sorting by retention” process and concentration increase of intravesicular catecholamine. The methodology is applicable to understanding soft nanoparticle collisions on electrodes, vesicles in exocytosis and phagocytosis, intracellular vesicle transport, and analysis of electroactive drugs in exosomes.

Linearization Trade-Offs in a 5G mmWave Active Phased Array OTA Setup

The new generation of 5G mobile communication systems is using millimeter wave (mmWave) active phased arrays (APA) which have up to hundreds of individual analog transmitter and receiver chains and antennas. For these highly integrated systems linearization of each analog path is very challenging. Therefore a single input single output (SISO) system in combination with over the air (OTA) measurement is considered as an efficient approach for linearization. However, the knowledge about the dependency of the total SISO nonlinearity on the contributions from different blocks in the antenna array, as well as the linearization trade-offs is still missing. In this paper, an overview of the possible linearization trade-offs in an OTA setup with a mmWave APA is provided. The linearization technique is applied to a $4\times 4$ active phased array containing up-conversion of a sub 6 GHz LTE10 signal to an RF frequency of 28 GHz. Through measurements, the effects on adjacent channel power ratio (ACPR) and error vector magnitude (EVM) have been investigated for the following scenarios: i. impact from the up-converter, ii. impact of the steering angle due to antenna crosstalk and iii. a linearity comparison between a linearized and a backed-off system.

The home range of adult Phrynops geoffroanus (Testudines, Chelidae) in relation to sex and body mass

Studying how different variables influence the size and shape of animals’ home ranges helps our understanding of the ecology of individuals and populations. This study aims to assess the effects of sex and body mass on home range size and the sexual differences in the use of terrestrial habitats of a population of aquatic turtles Phrynops geoffroanus from an urban area in Mato Grosso do Sul, Brazil. Turtles were captured along a river by active search, occasional encounter and hoop traps. Using individual VHF radio transmitters, 13 individuals (7 females and 6 males) were radio-tracked by homing in on the signal strength of the transmitter. Home ranges were estimated by 95% and 50% core one-dimensional fixed kernel and linear distance method. Home ranges were similar for both sexes (t = -0.50, DF = 12, p = 0.62) and independent of body mass (t = -0.53, DF = 12, p = 0.60). However, females seemed to use terrestrial habitats more than males (females = six recorded locations out of 767 points; males = none), probably to nest. To gain insight on how males and females use their space, it would be useful to focus future studies on the influence of sex in microhabitat selection of Phrynops geoffroanus. Finally, as sex did not influence home range, studying the contribution of other variables – both intrinsic, as age or personality, and extrinsic, as habitat composition or distribution of trophic resources – shaping the home ranges of the species is proposed.

Preliminary design and characterization of a low-cost and low-power visible light positioning system.

Designs and results for a low-power and economical fingerprint visible light positioning (VLP) system are discussed in this paper. A system using four white LEDs and one photodiode was deployed. The LEDs are independently controlled and modulated by individual transmitter circuits, removing the requirement for a large, expensive signal generator. The receiver circuit filters and converts the received signal to DC, allowing a simple microcontroller to save the received signal. We propose the creation of a fingerprint database by recording signal data, fitting a two-dimensional Gaussian distribution to the data, and then generating the fingerprint database for all positions in the evaluation system. System positioning accuracy of 13.44+/-0.36 mm was observed, corresponding to a relative error of 2.8% with respect to the system dimensions. This result presents an improvement on positioning accuracy for fingerprint positioning VLP systems, which build their own transmitters.

Effects of VLF Transmitter Waves on the Inner Belt and Slot Region

AbstractSignals from very low frequency (VLF) transmitters can leak from the Earth‐ionosphere wave guide into the inner magnetosphere, where they propagate in the whistler mode and contribute to electron dynamics in the inner radiation belt and slot region. Observations show that the waves from each VLF transmitter are highly localized, peaking on the nightside in the vicinity of the transmitter. In this study we use ∼5 years of Van Allen Probes observations to construct global statistical models of the bounce‐averaged pitch angle diffusion coefficients for each individual VLF transmitter, as a function of L*, magnetic local time (MLT), and geographic longitude. We construct a 1‐D pitch angle diffusion model with implicit longitude and MLT dependence to show that VLF transmitter waves weakly scatter electrons into the drift loss cone. We find that global averages of the wave power, determined by averaging the wave power over MLT and longitude, capture the long‐term dynamics of the loss process, despite the highly localized nature of the waves in space. We use our new model to assess the role of VLF transmitter waves, hiss waves, and Coulomb collisions on electron loss in the inner radiation belt and slot region. At moderate relativistic energies, E∼500 keV, waves from VLF transmitters reduce electron lifetimes by an order of magnitude or more, down to the order of 200 days near the outer edge of the inner radiation belt. However, VLF transmitter waves are ineffective at removing multi–megaelectron volt electrons from either the inner radiation belt or slot region.

Behavior Modeling and Individual Recognition of Sonar Transmitter for Secure Communication in UASNs

It is necessary to improve the safety of the underwater acoustic sensor networks (UASNs) since it is mostly used in the military industry. Specific emitter identification is the process of identifying different transmitters based on the radio frequency fingerprint extracted from the received signal. The sonar transmitter is a typical low-frequency radiation source and is an important part of the UASNs. Class D power amplifier, a typical nonlinear amplifier, is usually used in sonar transmitters. The inherent nonlinearity of power amplifiers provides fingerprint features that can be distinguished without transmitters for specific emitter recognition. First, the nonlinearity of the sonar transmitter is studied in-depth, and the nonlinearity of the power amplifier is modeled and its nonlinearity characteristics are analyzed. After obtaining the nonlinear model of an amplifier, a similar amplifier in practical application is obtained by changing its model parameters as the research object. The output signals are collected by giving the same input of different models, and, then, the output signals are extracted and classified. In this paper, the memory polynomial model is used to model the amplifier. The power spectrum features of the output signals are extracted as fingerprint features. Then, the dimensionality of the high-dimensional features is reduced. Finally, the classifier is used to recognize the amplifier. The experimental results show that the individual sonar transmitter can be well identified by using the nonlinear characteristics of the signal. By this way, this method can enhance the communication safety of the UASNs.

Buck-Boost Single-Inductor Multiple-Output High-Frequency Inverters for Medium-Power Wireless Power Transfer

In this paper, a nonisolated buck-boost single-inductor multiple-output (SIMO) dc–ac inverter for driving multiple independent high-frequency ac outputs of medium power is proposed. Compared with traditional bridge-type inverters, the proposed buck-boost SIMO inverter achieves 1) a smaller component count, 2) fully independent power control of its outputs, 3) better scalability in increasing the number of ac output channels, and 4) higher power efficiency. Operating in pseudo-continuous conduction mode, the rated power of each output channel of this inverter can be high while attaining zero cross regulation. The scalability factor of the proposed inverter is formally investigated and the theoretical maximum number of ac outputs is analytically derived. The targeted application of this SIMO-based inverter is for driving multiple transmitter coils to realize versatile multidevice medium-power wireless power transfer. A hardware prototype of a single-inductor three-output buck-boost inverter delivering a medium power of 8.4 W per output channel has been constructed. It is experimentally verified that precise and independent current regulation of individual transmitter coil is achievable with the proposed inverter.

Dynamic Wireless Power Transfer System for Electric Vehicles Employing Multiplexing LCC Modules With Individual Transmitters

Dynamic wireless power transfer (DWPT) of electric vehicles employing individual transmitters is getting popular owing to the advantages of high efficiency and less unwanted magnetic field emissions. However, too many power supply devices and passive components of compensation networks will make individual-transmitter-type DWPT systems under intense cost pressure for a long charging lane. Besides, circuit parameters of different transmitters will be different due to unignored component errors. Therefore, in this paper, a cost-reducing multiplexing LCC module (MLM) is proposed, and the effects of passive component errors are considered. An MLM makes unenergized transmitter work as a part of LCC compensation network resulting in no additional inductor. Simultaneously, one power inverter is shared by two transmitters in an MLM and 50% of inverters can be reduced. A novel distribution method and matched controlling storage of MLMs are proposed so that any two adjacent transmitters can be controlled independently and simultaneously. Due to passive component errors, unwanted reactive load will be placed on the inverter, and different transmitters will have different output power even in the same coupling and loading condition. A voltage adjustment method and a redistribution of passive components for MLMs are proposed to solve these problems. At last, a 6-kW-level laboratory scale prototype has been constructed and tested.

Simultaneous excitation system for efficient guided wave structural health monitoring

Many structural health monitoring systems utilize guided wave transducer arrays for defect detection and localization. Signals are usually acquired using the “pitch-catch” method whereby each transducer is excited in turn and the response is received by the remaining transducers. When extensive signal averaging is performed, the data acquisition process can be quite time-consuming, especially for metallic components that require a low repetition rate to allow signals to die out. Such a long data acquisition time is particularly problematic if environmental and operational conditions are changing while data are being acquired. To reduce the total data acquisition time, proposed here is a methodology whereby multiple transmitters are simultaneously triggered, and each transmitter is driven with a unique excitation. The simultaneously transmitted waves are captured by one or more receivers, and their responses are processed by dispersion-compensated filtering to extract the response from each individual transmitter. The excitation sequences are constructed by concatenating a series of chirps whose start and stop frequencies are randomly selected from a specified range. The process is optimized using a Monte-Carlo approach to select sequences with impulse-like autocorrelations and relatively flat cross-correlations. The efficacy of the proposed methodology is evaluated by several metrics and is experimentally demonstrated with sparse array imaging of simulated damage.

Deterministic Pilot Design for Sparse Channel Estimation in MISO/Multi-User OFDM Systems

We study the pilot design problem for sparse channel estimation in OFDM systems where multiple channels are estimated at a single antenna receiver. Such design is applicable to downlink of massive-MIMO systems and also to scenarios where multiple users transmit to a base station at the same carrier frequency. In our design, we deviate from the conventional orthogonal pilot arrangements by assigning the same pilot subcarriers to all transmitters. In the proposed setting, the achieved improvement in spectral efficiency (by reducing pilot overhead) may come at the expense of a more challenging channel estimation block at the receiver. To address this challenge and distinguish between different signals that are arriving at the receiver at the same subcarrier, we propose to select pilot subcarriers through minimizing the coherence of the associated Fourier submatrix, as well as properly assigning different pilot values (complex numbers) to each individual transmitter. We demonstrate that if the channels are sparse enough in time domain, there are simple sparse recovery techniques to simultaneously estimate all the channels, although all transmitters share the same pilot subcarriers. Simulation results demonstrate that the proposed design outperforms existing methods in terms of both mean-square channel estimation error and bit error rate.