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IEEE Transactions on Aerospace and Electronic Systems
Journal Prestige (SJR): 0.611
Citation Impact (citeScore): 3
Number of Followers: 363  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0018-9251
Published by IEEE Homepage  [228 journals]
  • IEEE Aerospace and Electronic Systems Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Joint Trajectory and Ranging Offset Estimation for Accurate Tracking in
           NLOS Environments
    • Authors: Shenghong Li;Mark Hedley;Iain B. Collings;David Humphrey;
      Pages: 3 - 14
      Abstract: The performance of a range-based indoor positioning system is severely degraded by non-line-of-sight (NLOS) propagation due to the offsets in range measurements (i.e., NLOS errors). It is difficult to predict or mitigate the NLOS errors since they are dependent on both the location and the environment. In this paper, we propose an accurate tracking scheme for NLOS environments by jointly estimating the target's trajectory and the NLOS errors based on the fusion of sensors that measure the motion of the target. We first formulate a maximum a posteriori (MAP) estimation problem with generic equality constraints that capture the spatial correlation of NLOS errors. A specific constraint function based on Gaussian process (GP) regression is then provided, and an iterative algorithm is proposed to solve the optimization problem. The proposed scheme is validated experimentally in an indoor positioning system with 125 MHz bandwidth using a mobile node equipped with an inertial measurement unit. It is shown that the median positioning error in an office environment is reduced by 90% to 11 cm compared to using conventional tracking algorithms.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • ISHM-Oriented Time Decision-Making for Condition-Based Maintenance of
           Multistate Systems
    • Authors: Zhengqiang Zhong;Lei Xu;Jiuping Xu;
      Pages: 15 - 29
      Abstract: In this paper, an integrated system health management oriented condition monitoring and maintenance decision-making model is proposed, which uses intelligent mobile agents to achieve real-time monitoring and to realize life cycle maintenance decision-making for multistate systems (MSSs). The model is applied to an aircraft engine system numerical example, the results of which illustrate that the proposed system and model have the ability to provide efficient and accurate engine system maintenance decision-making information and provide detailed health condition information. The feasibility of the proposed system and model is demonstrated and MSS frequent maintenance decisions are recorded and revealed.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Time Synchronization in Photon-Limited Deep Space Optical Communications
    • Authors: Muhammad Salman Bashir;Sajid Sheikh Muhammad;
      Pages: 30 - 40
      Abstract: Random jitter or offset between the transmitter/receiver clocks is an important parameter that has to be accurately estimated for optimal detection of pulse position modulation (PPM) symbols for high-data-rate optical communications. This parameter, in general, is modeled as an unknown random quantity that depends on the clock drift between the transmitter/receiver clocks and the random motion between the transmitter and receiver stations. In this paper, we have modeled the time jitter for two scenarios-phase modulation jitter and frequency modulation jitter. The phase modulation jitter is modeled as a Gaussian random variable which is estimated with the help of a maximum a posteriori probability (MAP) estimator. The frequency modulation jitter is characterized as a random walk, and this leads to the modeling of the jitter as a state space variable in the context of a dynamical system. Since the observations are the photon counts in each slot of a PPM symbol (for both MAP estimation and tracking), the resulting dynamical model is highly nonlinear, and particle filters are employed for tracking the frequency modulation jitter. We evaluate the performance of both the maximum a posteriori estimators and the particle filters in terms of the relative mean-square error and probability of error. We conclude that with MAP estimation and particle filters that estimate/track the time offset, we achieve a significant performance gain in terms of probability of error as compared to systems that do not have a time synchronization system in place.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Distance-Based Multiagent Formation Control With Energy Constraints Using
    • Authors: Reza Babazadeh;Rastko Selmic;
      Pages: 41 - 56
      Abstract: We present an optimal control method for distance-based formation control of multiagent systems with energy constraints. We combine the rigid graph theory and state-dependent Riccati equation method to develop a multiagent formation control scheme. We defined a normalized rigidity matrix and use it for the rigorous stability analysis. The proposed method asymptotically minimizes weighted cost functional that includes formation and energy consumption costs. Furthermore, we propose a solution for the global asymptotic stability and collision avoidance. Simulation results illustrate the effectiveness of the proposed method in two- and three-dimensional spaces.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Finite-Difference Algorithm for Polynomial Phase Signal Parameter
    • Authors: Nathan Madsen;Siyang Cao;
      Pages: 57 - 66
      Abstract: A new algorithm, the finite-difference algorithm, is proposed for single-component polynomial phase signal parameter estimation. The proposed algorithm takes advantage of the framework of the quasi-maximum-likelihood (QML) estimator but estimates the finite difference of the polynomial instead of the derivative. The algorithm is computationally simpler and has comparable performance to the QML algorithm. A phase centering step is proposed to increase the detectable range of polynomial phase parameters as an alternative to phase unwrapping.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • An Approach for Parameter Estimation of Maneuvering Targets With Nonlinear
    • Authors: Wei Cui;Jing Tian;Xiang-Gen Xia;Si-Liang Wu;
      Pages: 67 - 83
      Abstract: To compensate the range cell migration and Doppler frequency spread of a maneuvering target during the integration time, this paper proposes a new parameter estimation method based on sub-band dual-frequency conjugate (SDFC)–Radon chirp rate–quadratic chirp rate algorithm. In this method, SDFC process is first applied to reduce the equivalent frequency and Radon chirp rate–quadratic chirp rate algorithm is then performed to obtain the estimates. Both simulated and real-data results demonstrate the effectiveness of the proposed algorithm.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Adaptive Nonlinear Tracking Control Algorithm for Quadcopter Applications
    • Authors: Seok-Kyoon Kim;Choon Ki Ahn;
      Pages: 84 - 94
      Abstract: This paper presents a nonlinear tracking controller including the cutoff frequency adaptation algorithm for quadcopters without the use of true plant parameters. This study makes two contributions. First, an adaptation algorithm automatically updates the closed-loop cutoff frequency by updating the feedback gains. Second, a nonlinear control law renders the closed-loop system to guarantee the exponential performance recovery and offset-free properties, while only using the proportional component of tracking errors. The numerical verifications are performed to verify the closed-loop performance improvement from the proposed controller with MATLAB/Simulink.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Timing Assurance of Avionic Reconfiguration Schemes Using Formal Analysis
    • Authors: Antonio Augusto da Fontoura;Francisco Assis Moreira do Nascimento;Simin Nadjm-Tehrani;Edison Pignaton de Freitas;
      Pages: 95 - 106
      Abstract: Reconfigurable avionics systems can tolerate faults by moving functionalities from failed components to another available system component. This paper proposes a distributed reconfigurable architecture for application migration from failed modules to working ones. The feasible system reconfiguration states are determined off-line to provide the expected configuration in foreseen situations. Model checking is used to determine feasible configurations evaluating specific temporal properties. A case study is used to show the application of the presented approach as a proof of concept.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Parameter Estimation of Radar Noise Model for Terrain Referenced
           Navigation Using a New EM Initialization Method
    • Authors: Jungmin Park;Yong-gonjong Park;Chan Gook Park;
      Pages: 107 - 112
      Abstract: In this paper, we present an expectation-maximization (EM) initialization method for estimation of unknown parameters in a radar noise model. We deal with radar based terrain referenced navigation (TRN) over vegetated areas, where the radar noise was modeled as a double-mode Gaussian mixture with two unknowns. The known parameters are used for EM initialization along with innovation samples. Through TRN simulation, it is shown that the proposed EM initialization method outperforms random or k-means initialization methods in terms of both the parameter estimation error and the vehicle position error.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Ultrawideband Network Channel Models for Next-Generation Wireless Avionic
    • Authors: Williams-Paul Nwadiugwu;Dong-Seong Kim;
      Pages: 113 - 129
      Abstract: This paper proposes an impulse radio ultrawideband (IR-UWB) wireless network channel model for next-generation wireless avionic system (NGWAS). Complexities such as poor network localization, redundant wiring, network security flaws, suitable physical proximity to the aircraft system's controller and need to guarantee scalable wireless network access have necessitated the adoption of wing system units of a passenger aircraft for this scheme's deployment. The proposed IR-UWB approach aims at alleviating the attendant drawbacks by selecting optimal channel path from available paths on the basis of bit error rate (BER), based on the numerical results obtained from the Saleh-Valenzuela (S-V) principle. Cooperative relay transmission schemes factored upon transmission power, overall outage probability and spectral-energy efficiency tradeoffs for the relay network communication were also investigated and compared with the noncooperative schemes. Simulation results validate maximum data packet delivery while a strong network signal strength is attained. Comparative approach of the performances of the IR-UWB standardized channel models are also evaluated.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Smart Gateway Diversity Optimization for EHF Satellite Networks
    • Authors: Tommaso Rossi;Mauro De Sanctis;Fabio Maggio;Marina Ruggieri;Craig Hibberd;Cristina Togni;
      Pages: 130 - 141
      Abstract: The short-term scenarios of high-throughput satellite systems foresee the exploitation of (currently commercially unused) extremely high frequency bands in the feeder link to support broadband user access services. In this context, spatial diversity plays a key role, considering that this is the only technique that can allow high link availability at frequency bands higher than the Ka-band without requiring very high link margins, which results in a waste of system resources. In this framework, the most promising spatial diversity technique is the so-called smart gateway (SG) diversity. This paper focuses on the optimization of the SG technique following operator perspectives and needs. In particular, a design approach for the optimization of the SG architecture is proposed, which allows to select the best SG configuration (spare capacity, number of gateway groups, number of gateways in each group, geographical position of gateways in each group) given a set of constraints (geographical position of all available gateways, longitude of the GEO satellite, characteristics of satellite/ground terminals, system availability). Moreover, a practical case of SG diversity optimization is presented as a reference to guide the reader in the SG optimization process.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Finite-State Markov Chains Channel Model for CubeSats Communication Uplink
    • Authors: Julian J. Lopez-Salamanca;Laio Oriel Seman;Marcelo D. Berejuck;Eduardo A. Bezerra;
      Pages: 142 - 154
      Abstract: This paper proposes a channel model to be applied to the communications systems of CubeSats. The model considers the low earth orbit geometry when a satellite is passing over a ground station, and the propagation surrounding multiple paths of the ground station location in urban areas. The geometry was used to define the deterministic factors, which contribute to the fading of the communication signal, such as Doppler effect and loss in free space. These are parameters that change as a function of time and elevation angle. Thus, a complete digital communication system, at the link layer level, is presented, using Markov Chains to model the previously cited effects in the form of a finite-state Markov channel. The proposed model was used as an uplink channel between a ground station and a CubeSat, both implementing a protocol stack, following the consultative committee for space data systems (CCSDS) recommendations. The ground station and the proposed communication channel were implemented through a functional simulation model and a telecommand and telemetry unit, implemented in hardware, was used as a case study for the CubeSat. Through the analysis of the simulated system, with telecommands sent by the station and responses sent by the hardware unit (in a hardware-in-the-loop setup), it was possible to demonstrate the operation of the proposed channel together with the retransmission mechanism suggested in the CCSDS recommendations, in order to mitigate communication issues.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • iPCM Telemetry Protocol: Reliability and Bandwidth Improvement for PCM
    • Authors: Marco Aurélio Carvalho;Nelson Paiva Oliveira Leite;Roberto d'Amore;
      Pages: 155 - 166
      Abstract: A reliable telemetry link is a key element to reduce reflies and to enhance test flight efficiency (i.e., real-time test point validation) and safety in flight test campaigns. However, the telemetry link undergoes losses owing to radio frequency noise and flight test maneuvers. In addition, the telemetry community has been facing a reduction of the available bandwidth owing to electromagnetic spectrum auctions. Many methods have been presented to solve these problems; however, no conclusive solution has been obtained. In view of these issues and by focusing on flight test requirements, IPEV, an Air Force Flight Test Center, proposed an integrated pulse code modulation (iPCM) Telemetry protocol as a potential solution to vital matters regarding the reliability and bandwidth of telemetry links. This paper presents the iPCM architecture and the ground and flight test results. Test results demonstrated the iPCM's capability to recover corrupted data and ensure data integrity and reliability. In a flight test, 100% of the data was successfully retrieved by iPCM without any noise and loss compared with the 98.24% received by PCM IRIG-106. Similarly, for the ground test results, 100% of the data was retrieved successfully by iPCM, and only 88.45% by PCM. In addition, the iPCM protocol provides an option to dynamically select an Flight Test Instrumentation parameter list to be transmitted. In a typical test scenario, this feature of frame changing in the parameter list can achieve a 65% reduction in the bandwidth usage in comparison with PCM IRIG-106.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • One-Bit Compressive Radar Sensing in the Presence of Clutter
    • Authors: Sayed Jalal Zahabi;Mohammad Mahdi Naghsh;Mahmoud Modarres-Hashemi;Jian Li;
      Pages: 167 - 185
      Abstract: We propose a compressive pulse-Doppler radar that works through one-bit quantization of the received noisy signal by comparing it with a time-varying reference level. Considering the sparsity of the targets in the range-Doppler domain, we solve the problem by sparse recovery methods in both the absence and presence of clutter. The proposed method leads to an optimization problem that can be tackled by a convex approximation. Numerical examples confirm the effectiveness of the proposed method.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Thermal Analysis of the Solar Orbiter PHI Electronics Unit
    • Authors: Ignacio Torralbo;Isabel Pérez-Grande;José Luis Gasent-Blesa;Javier Piqueras;Esteban Sanchis-Kilders;Pedro Rodríguez;Antonio López;
      Pages: 186 - 195
      Abstract: This paper presents the thermal design of the electronics unit of the instrument Polarimetric Helioseismic Imager, onboard the European Space Agency mission Solar Orbiter. The thermal design procedure, along with the problems encountered during this design phase, and the solutions found to fix them are described, proving in this way the thermal feasibility and robustness of the unit. Its final thermal behaviour, obtained from thermal analyses correlated with data from thermal tests performed in a vacuum environment, is presented.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Survivability Simulation of Airborne Platform With Expendable Active Decoy
           Countering RF Missile
    • Authors: Jae-Won Rim;Il-Suek Koh;
      Pages: 196 - 207
      Abstract: By employing an expendable repeater-type decoy that is known as efficient electronic countermeasure device, the survivability of an airborne platform can be improved. To optimize the survivability of the aircraft by managing the active decoy, analyzing which factors critically affect to the survivability is very important. For its dynamic situation, where the motions and interaction of the decoy, platform, and missile varied with respect to time, a modeling and simulation (M&S) approach is preferred, which can consider other factors: radio frequency specification of decoy, guidance model of the missile, and so on. Based on the proposed M&S approach, several crucial factors affecting to the survivability of the platform such as platform reaction range, platform maneuvering, decoy dynamics, missile's maximum load factor, etc., are addressed and numerically analyzed. Additionally, the survival probability of the platform is also simulated on several engagement scenarios through the Monte Carlo simulation.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Poisson Multi-Bernoulli Mixture Conjugate Prior for Multiple Extended
           Target Filtering
    • Authors: Karl Granström;Maryam Fatemi;Lennart Svensson;
      Pages: 208 - 225
      Abstract: This paper presents a Poisson multi-Bernoulli mixture (PMBM) conjugate prior for multiple extended object filtering. A Poisson point process is used to describe the existence of yet undetected targets, while a multi-Bernoulli mixture describes the distribution of the targets that have been detected. The prediction and update equations are presented for the standard transition density and measurement likelihood. Both the prediction and the update preserve the PMBM form of the density, and in this sense, the PMBM density is a conjugate prior. However, the unknown data associations lead to an intractably large number of terms in the PMBM density, and approximations are necessary for tractability. A gamma Gaussian inverse Wishart implementation is presented, along with methods to handle the data association problem. A simulation study shows that the extended target PMBM filter performs well in comparison to the extended target δ-generalized labelled multi-Bernoulli and LMB filters. An experiment with Lidar data illustrates the benefit of tracking both detected and undetected targets.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Target Motion Parameters Estimation in Forward Scatter Radar
    • Authors: Nertjana Ustalli;Debora Pastina;Pierfrancesco Lombardo;
      Pages: 226 - 248
      Abstract: This paper is devoted to the estimation of target motion parameters with a forward scatter radar (FSR). To provide an upper bound for the estimation performance, a closed-form expression of the Cramér-Rao lower bound (CRLB) is provided for the main target signal parameters, namely Doppler rate, baseline crossing instant, and main lobe width parameter of the target amplitude modulation pattern. This is performed by operating on the signal at the output of the standard FSR processing scheme, namely on the crystal video detector signal: the received signal, which is passed through a square-law envelope detector followed by a DC removal filter. The estimate of the kinematic parameters of moving targets that follow a linear trajectory can be obtained by inverting the relationship between these parameters and the previously estimated target signal parameters. Especially, two FSR configurations are investigated: single-node FSR configuration and dual-baseline FSR configuration with a small angular separation between the two baselines. The closed-form expression of the corresponding CRLB is derived by using a linearized version of the same inverse transformation. Finally, a practical estimator is presented, based on a two-dimensional filter bank, and its performance is compared with the derived CRLB. The results show that unbiased and highly accurate estimates of the kinematic parameters are obtained. The feasibility and the effectiveness of this estimation scheme is demonstrated by applying this technique to recorded live data acquired with a dual-baseline FSR configuration exploiting FM signals as a waveform of opportunity.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • GPS Multireceiver Direct Position Estimation for Aerial Applications
    • Authors: Arthur Hsi-Ping Chu;Shubhendra Vikram Singh Chauhan;Grace Xingxin Gao;
      Pages: 249 - 262
      Abstract: Modern aviation safety increasingly depends on reliable GPS services, while signal degrading effects such as multipath and masking often occur during critical flight phases, such as takeoff and landing. In this regard, we propose multireceiver direct position estimation (MR-DPE), which operates a network of DPE receivers to enhance GPS accuracy under degraded signal conditions. A DPE receiver directly estimates navigation solutions in the position–velocity–time domain with a maximum-likelihood approach, bypassing the intermediate range measurements. Whereas prior works have shown the enhanced accuracy of DPE with weak signals, MR-DPE provides further improvement by leveraging the information redundancy and the geometric diversity provided by the network of receivers and antennas. We implemented MR-DPE using software-defined radio and tested it with simulated GPS signals to show improved GPS accuracy under degraded environments. We conducted comprehensive, full-scale flight experiments, a first for DPE-related works. A wide range of flight profiles was explored and analyzed, especially those prone to signal multipath and masking, thus validating the claimed benefits of MR-DPE in GPS accuracy.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Toward Optimized Network Capacity in Emerging Integrated
           Terrestrial-Satellite Networks
    • Authors: Shulei Gong;Hong Shen;Kanglian Zhao;Wenfeng Li;Haibo Zhou;Ruhai Wang;Zhili Sun;Xinggan Zhang;
      Pages: 263 - 275
      Abstract: In this paper, we investigate the transmission schemes of space data systems for optimized network capacity in an integrated terrestrial-satellite network (ITSN) with a two-layered space segment. First, a theoretical model of the network capacity is developed to evaluate the strategy of utilizing both direct and relayed transmissions. Second, we consider the ideal and the resource-constrained scenarios in which the corresponding network capacity is modeled with respect to the scheduling scheme. In particular, closed form and semi-closed form solutions to difficult integer programs are achieved via rigorous mathematical analysis. The proposed model is general for exploring the capacity of various satellite network deployments whose solutions have not been obtained in prior studies. Furthermore, we verify the potential capacity of the different transmission schemes based on the proposed solutions and prove that the system's network capacity can be significantly improved by the hybrid transmission scheme. The theoretical framework proposed in this paper is expected to provide constructive insights in the design for the future space segments of ITSNs.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • MAIDENS: MIL-STD-1553 Anomaly-Based Intrusion Detection System Using
           Time-Based Histogram Comparison
    • Authors: Sébastien J. J. Généreux;Alvin K. H. Lai;Craig O. Fowles;Vincent R. Roberge;Guillaume P. M. Vigeant;Jeremy R. Paquet;
      Pages: 276 - 284
      Abstract: Aircraft are becoming increasingly connected to other systems or networks, introducing attack vectors and posing a threat to their operational effectiveness. Many military aircraft function using the MIL-STD-1553 protocol in order to communicate information across its systems. Previous intrusion detection research on this type of data bus is unable to detect spoofing attacks where only data words are manipulated. This paper presents the design of a MIL-STD-1553 anomaly-based intrusion detection system able to identify those attacks through the use of a novel histogram comparison approach and time-based features. The approach includes optimizations for improved time resolution in threat identification. Results demonstrate the effectiveness of the approach in identifying threats quickly and accurately.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • $Q/V$ -Band+Feeder+Links&rft.title=IEEE+Transactions+on+Aerospace+and+Electronic+Systems&rft.issn=0018-9251&;&rft.aufirst=Thomas&;Andreas+Knopp;">Smart Diversity Through MIMO Satellite $Q/V$ -Band Feeder Links
    • Authors: Thomas Delamotte;Andreas Knopp;
      Pages: 285 - 300
      Abstract: With sum throughputs exceeding 1 Tb/s, next-generation high throughput satellite will play a key role in 5G networks for applications including backhauling or broadband in-flight connectivity. Such satellites require the deployment of tens of Q/V-band feeder links to support the data traffic in their uplink. Meanwhile, geographical restrictions and cost considerations significantly constrain the search for gateway deployment sites. Diversity strategies are, furthermore, necessary to cope with strong rain fades. In this paper, multiple-input-multiple-output (MIMO) feeder links are proposed to address these challenges. Using two active gateway antennas per feeder link, a MIMO-based solution enables to support twice the user link bandwidth per link compared to the state-of-the-art. On-ground and onboard processing strategies for such MIMO links are introduced, and the link outage probabilities are determined. An extension of smart diversity schemes to MIMO-based architectures is also presented to guarantee a sufficient robustness against rain fades. An analysis of the achieved uplink CINR demonstrates the superiority of the proposed concept and provides guidelines for an efficient design.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Nonlinear Estimation and Decision-Making Methods in Short Track
           Identification and Orbit Determination Problem
    • Authors: Alexei E. Kolessa;Alexander G. Tartakovsky;Atner P. Ivanov;Vasily A. Radchenko;
      Pages: 301 - 312
      Abstract: Typically, near-Earth space objects are observable for a small fraction of the orbit revolution. In this paper, we consider the problem of identification and fusion of two short optical tracks of near-Earth space objects, as well as the problem of estimation of the parameters of the corresponding orbits directly from these tracks in the absence of a priori information. The popular approach to solving these problems is based on admissible regions of orbital parameters, which is typically computationally demanding. It is shown that the solution of these problems does not require admissible regions and computationally and algorithmically difficult operations with admissible regions. A new, purely statistical method for solving these problems is proposed.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Gaussian Process Based Channel Prediction for Communication-Relay UAV in
           Urban Environments
    • Authors: Pawel Ladosz;Hyondong Oh;Gan Zheng;Wen-Hua Chen;
      Pages: 313 - 325
      Abstract: This paper presents a learning approach to predict air-to-ground communication channel strength to support the communication-relay mission using the unmanned aerial vehicle (UAV) in complex urban environments. The knowledge of the air-to-ground communication channel quality between the UAV and ground nodes is essential for optimal relay trajectory planning. However, because of the obstruction by buildings and interferences in the urban environment, modeling and predicting the communication channel strength is a challenging task. We address this issue by leveraging the Gaussian process (GP) method to learn the communication shadow fading in a given environment and then employing the optimization-based relay trajectory planning by using learned communication properties. The key advantage of this learning method over fixed communication model based approaches is that it can keep refining channel prediction and trajectory planning as more channel measurement data are obtained. Two schemes incorporating GP-based channel prediction into trajectory planning are proposed. Monte Carlo simulations demonstrate the performance gain and robustness of the proposed approaches over the existing methods.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Statistical Compressive Sensing and Feature Extraction of Time-Frequency
           Spectrum From Narrowband Radar
    • Authors: Ke Ren;Lan Du;Baoshuai Wang;Quan Li;Jian Chen;
      Pages: 326 - 342
      Abstract: Aiming at the signal reconstruction problem for the conventional narrowband radar system, we propose a new statistical compressive sensing (SCS) method to achieve the reconstruction of superresolution time-frequency spectrum from the corrupted time-domain measurement. The proposed method assumes that the signal obeys complex Gaussian distribution and develops a hierarchical Bayesian model. Variational Bayesian expectation maximization (VBEM) is used to perform inference for the posterior distributions of the model parameters. In order to fully exploit the superresolution characteristics of reconstructed spectrum, a novel superresolution time-frequency feature vector is extracted for subsequent classification of ground moving targets, i.e., walking person and a moving wheeled vehicle. Experimental results on measured data show that the proposed reconstruction method can obtain good reconstruction results and the superresolution feature has good classification performance for human and vehicle targets.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • CRLB for Estimating Time-Varying Rotational Biases in Passive Sensors
    • Authors: Michael Kowalski;Peter Willett;Tim Fair;Yaakov Bar-Shalom;
      Pages: 343 - 355
      Abstract: In target tracking systems involving data fusion it is common to encounter sensor measurement biases that contribute to the tracking errors. There is extensive research into estimating sensor biases, but very little research into bias estimation in the dynamic case, meaning that biases that change over time are addressed. This paper investigates the means for and necessity of estimating bias rates of change in addition to constant sensor biases to reduce the errors in the state estimates. This is explored by comparing the Cramér-Rao lower bound and root-mean-square error of simultaneous target state and bias estimates for rotational biases with three-dimensional passive sensors with roll, pitch, and yaw biases. The present work models the dynamic biases as linearly varying over time. The iterated least squares method is used for the search of the maximum likelihood estimate, and is shown to be statistically efficient via hypothesis testing.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Detection, Location Estimation, and CRLB of a Streaking Target in an FPA
           With a Poisson Model
    • Authors: Andrew Robert Finelli;Yaakov Bar-Shalom;
      Pages: 356 - 367
      Abstract: This paper deals with measurement extraction, from an optical sensor's Focal Plane Array (FPA), of a streaking target. We use a model that assumes pixels are separated by dead zones and model the streaking target's point spread function (PSF) as a Gaussian PSF that moves during the optical sensor's integration time. We make an assumption that the target has a constant velocity over the sampling interval and parametrize its motion with a starting and ending position. The noise model for a single pixel has variance proportional to its area, consistent with a Poisson model of the number of nontarget originated photons. We develop a maximum likelihood (ML) method of estimating the target motion parameter vector based on the set of pixel measurements from the optical sensor. This paper then derives the Cramer-Rao lower bound (CRLB) on the estimation error of the target motion parameter. We then present a matched filter (MF) based definition of the signal-to-noise ratio (SNR) to use as a basis for comparison of Monte Carlo simulation based location estimates to the calculated CRLB. It is shown that the ML estimator for the starting and ending positions of a streak in the FPA is efficient for MFSNR ≥ 12 dB. We then provide a test statistic for target detection and propose approximate distributions to set the detection threshold for specific detection (PD) and false alarm probabilities (PFA), which are then verified via simulations. This paper's major contributions are the proposal of an ML/MF method for measurement extraction of streaking targets, confirmation that this method achieves the best accuracy possible for realistic FPA sensors, i.e., it attains the CRLB, the introduction of a statistically supported definition of SNR for these measurements, and an evaluation of the target measurement detection performance. Furthermore, this paper shows that, given our MFSNR definition, the streak length and direction of motion in the-FPA have a negligible effect on performance compared to the SNR where we show that with a 4-dB change, the detection performance increases dramatically.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Digital Terrain Map Based Safe Landing Site Selection for Planetary
    • Authors: Youeyun Jung;Seongheon Lee;Hyochoong Bang;
      Pages: 368 - 380
      Abstract: Safe landing site selection of a planetary lander is one of the most important technologies for the lander's mission success. In this paper, a new concept for safe landing site selection is proposed based on the digital terrain map and contour lines generated by light detection and ranging (LIDAR) measurements. The design parameters of the proposed approach are defined and systematically classified. Then, the effect of key parameters related to the performance of the algorithm, i.e., terrain roughness is analyzed by comparing the results of three different types of terrain. The simulation results show that the proposed method is well-performed under various circumstances.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Configurable GPS/GNSS Antenna Module Resistant to RFI Saturation
    • Authors: Yafeng Li;Jorge Cervantes;Nagaraj C. Shivaramaiah;Dennis M. Akos;Meiling Wang;
      Pages: 381 - 392
      Abstract: With GPS/Global Navigation Satellite System (GNSS) receivers exposed to greater levels of Radio Frequency Interference (RFI), a potential problem is the saturation of the receiver front end (FE). This problem is further complicated in typical multifrequency receivers by the interfrequency saturation effect. Specifically, any inband RFI targeted to induce FE saturation at only one specific GPS/GNSS frequency, if not properly handled, would potentially impact the reception of the other frequencies. This paper presents the design of an antenna module to detect, identify, and isolate potential RFI to prevent FE saturation including that due to the interfrequency effect. Analysis showed that any specific antenna module configuration with fixed internal components must sacrifice noise figure (NF) performance to increase robustness to RFI saturation, and vice versa. To provide a compact solution to this dilemma and the interfrequency saturation issue, two dynamically configurable antenna modules based on the concept of network topology were proposed for typical dual-frequency GPS/GNSS receivers. Such a solution can adapt to different RFI conditions by operating in corresponding modes resulting in a better NF versus robustness tradeoff. The proposed antenna-module design was validated by experiments with live GPS signals under controlled RFI conditions.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Verification of Radiated Emissions Modeling for SpaceWire/LVDS
           Links Routed on CFRP Ground
    • Authors: Christos D. Nikolopoulos;Anargyros T. Baklezos;Stylianos Tsatalas;Christos N. Capsalis;
      Pages: 393 - 402
      Abstract: In their previous work, the authors proposed a methodology for predicting and modeling electromagnetic emissions in case of shielded coaxial cable with respect to the ground dielectric properties. In that work, a shielded coaxial cable was treated as a travelling wave antenna and the decomposed contribution of each phenomenon was validated through extensive electric field measurements of the cable over various ground planes and heights. In the present paper, the authors attempt to verify the applicability of this methodology in more complex structures; exploring the case of SpaceWire (SpW) cable over a carbon-fiber-reinforced polymer ground. This setup is of major interest for space applications, as it becomes the standard harness and grounding design for the majority of space missions. SpW is a space-application focused cable with four shielded twisted pairs employing low-voltage differential sign signaling, a geometry requiring rather cumbersome calculations in order to analytically extract the radiated emissions. The authors showcase that this issue can be bypassed with the proposed methodology, while measurements verify the validity of this claim also for the case of complex structures
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Packet Layer Erasure Coding in Interplanetary Links: The LTP Erasure
           Coding Link Service Adapter
    • Authors: Nicola Alessi;Carlo Caini;Tomaso de Cola;Marco Raminella;
      Pages: 403 - 414
      Abstract: Interplanetary networks are affected by long propagation delays, intermittent connectivity, possible packet losses due to residual errors, and other impairments. To cope with these challenges, the delay-/disruption-tolerant networking (DTN) architecture utilizes the Licklider transmission protocol (LTP) as convergence layer on space links. The LTP reliable service (red) relies on Automatic Repeat reQuest, but very long propagation delays make packet layer forward error correcting (PL-FEC) codes very appealing to protect LTP segments from losses. The key advantage of FEC is that LTP retransmissions would be limited to the unlikely case of decoding failures. To this end, a new FEC-based protocol, to be inserted immediately below LTP, the erasure coding link service adapter (ECLSA), is presented here. ECLSA is completely transparent to LTP, relies on two alternative external libraries for coding/decoding, LibecDLR and OpenFEC, both using low density parity check codes and it is fully integrated with the ION DTN software package of NASA-JPL. This paper aims to provide a solid description of ECLSA, including features functional in a real deployment (such as the dynamic selection of codes). Performance is evaluated at the end of the paper, with nearly ideal results. ECLSA is released as free software and is already included in the “contrib” section of ION.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Robust Rauch–Tung–Striebel Smoothing Framework for
           Heavy-Tailed and/or Skew Noises
    • Authors: Yulong Huang;Yonggang Zhang;Yuxin Zhao;Lyudmila Mihaylova;Jonathon A. Chambers;
      Pages: 415 - 441
      Abstract: A novel robust Rauch–Tung–Striebel smoothing framework is proposed based on a generalized Gaussian scale mixture (GGScM) distribution for a linear state-space model with heavy-tailed and/or skew noises. The state trajectory, mixing parameters, and unknown distribution parameters are jointly inferred using the variational Bayesian approach. As such, a major contribution of this paper is unifying results within the GGScM distribution framework. Simulation and experimental results demonstrate that the proposed smoother has better accuracy than existing smoothers.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Robust Polarimetric Adaptive Detector Against Target Steering Matrix
    • Authors: Lei Shen;Zhiwen Liu;Yougen Xu;Yang Bai;Tao Zhao;
      Pages: 442 - 455
      Abstract: A polarimetric scheme is presented for the detection of a range-spread target when the presumed target steering matrix is deviated from the actual one. Following the adaptive beamformer orthogonal rejection test model, the decision statistic of the proposed detector involves the polarimetric clutter-plus-noise covariance matrix, the target component after noise whitening and rotation, as well as the sidelobe interference vectors of multiple range cells. In the practical realization of the detector, the polarimetric clutter-plus-noise covariance matrix is estimated by using the minimum mean-square-error regularized secondary data sample averaging. Taking into account the mismatch involved in the presumed target steering matrix, the target component is obtained by least square fitting subject to multiple separate conic uncertainty set constraints. The estimation of the sidelobe interference vectors is also based on the Bayesian statistics, and the involved polarimetric clutter-plus-noise covariance matrix is ultimately replaced by its Bayesian estimate previously obtained. The performance of the proposed detector has been evaluated and compared with the existing popular polarimetric detectors using both synthetic and real data. The results show that in the presence of target steering matrix mismatch caused by pointing errors, sensor position errors, channel calibration errors, multipath propagation, and random errors, the proposed detector has a superior performance to the current detectors in terms of the probability of detection.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Dynamic Code Selection Method for Content Transfer in Deep-Space Network
    • Authors: Rojina Adhikary;John N. Daigle;Lei Cao;
      Pages: 456 - 474
      Abstract: To maximize file transfer from deep-space vehicles, a space-to-earth content-transfer protocol that combines turbo codes, RaptorQ codes, real-time channel prediction, and dynamic code-rate selection is proposed. The protocol features a signal-to-noise ratio prediction model that facilitates the periodic adjustment of turbo encoder to achieve adaptive-rate transmission, and fountain codes to eliminate retransmission of specific packets. Simulation results indicate that an increase of about 132% in file transfer rate is achievable compared to fixed-rate transmission scheme.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Exploiting Channel Crosstalk for Polarimetric SAR Compressive Sensing
    • Authors: Julie Ann Jackson;Forest Lee-Elkin;
      Pages: 475 - 485
      Abstract: We propose a new compressive sensing scheme that enables fully polarimetric radar imaging from a subset of channel measurements. Previous sparse recovery methods for polarimetric radar have not modeled channel coupling. We recognize that mixing of information through coupling is key to dropping a channel. Our method complements fast and slow time sampling and may reduce hardware and communications costs. This paper provides the signal model and examples of successful four-channel recovery when only three are measured.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Product of Squared SR Random Variables: Application to Satellite
    • Authors: Arti M. K.;
      Pages: 486 - 496
      Abstract: We investigate the problem associated with the statistics of the product of two squared Shadowed Rician (SR) random variables (RVs). Both SR RVs are independent and nonidentically distributed. The distribution of the product of two squared SR RVs is very important from the satellite communication perspective. We derive approximate expressions of the probability density function (p.d.f.), the moment generating function (m.g.f.), and the cumulative distribution function (c.d.f.) in terms of Meijer-G functions. Furthermore, exact closed-form expressions for higher order moments, channel quality estimation index, and amount of fading are derived. The outage probability is also discussed by utilizing the expression of the c.d.f. An approximate closed-form expression of channel capacity is also derived with the help of the p.d.f. expression. Furthermore, the performance of satellite communication system is discussed in terms of the approximate symbol error rate by using the derived results. Specifically, the derived expression of the p.d.f. is used to develop an approximate closed-form expression of the m.g.f. for an amplify-and-forward-based satellite communication system.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • DOA and Phase Error Estimation for a Partly Calibrated Array With
           Arbitrary Geometry
    • Authors: Xuejing Zhang;Zishu He;Xuepan Zhang;Yue Yang;
      Pages: 497 - 511
      Abstract: This paper presents a novel strategy to simultaneously estimate the direction of arrival (DOA) of a source signal and the phase error of a partly calibrated array with arbitrary geometry. We add up the snapshot data of two different sensors, and then extract a knowledge associated with the DOA and phase errors of these two elements by using singular value decomposition. In such a manner, we can establish a series of linear equations with respect to the unknown DOA and phase error, by simply conducting the procedure on any two sensor elements. On this basis, it can be shown that the problem of jointly estimating DOA and phase error is equivalent to a least square (LS) problem with a quadratic equality constraint. To solve this LS problem (so that the DOA and phase error can be obtained), an effective convex-concave procedure is employed. Different from the conventional algorithms that are limited to specific array geometries, the proposed one is suitable for arrays with arbitrary geometries. More importantly, the devised method only requires one extra calibrated sensor, which is not necessarily adjacently located with the reference one. Several simulations are carried out in this paper and the effectiveness of the devised method can be clearly observed.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • A Pose Measurement Method of a Space Noncooperative Target Based on
           Maximum Outer Contour Recognition
    • Authors: Jianqing Peng;Wenfu Xu;Lei Yan;Erzhen Pan;Bin Liang;Ai-Guo Wu;
      Pages: 512 - 526
      Abstract: The relative pose (position and attitude) measurement of space noncooperative targets is very important for on-orbit servicing activities, such as target tracking, approaching, and capturing. The traditional methods rarely consider the instability of feature extraction and image blurring caused by target tumbling. In this paper, a method based on the maximum outer contour (MOC) recognition is proposed to measure the pose of the target. Different feature extraction algorithms can simultaneously achieve close- and long-range measurement tasks. First, the trailing image is restored by the image enhancement method. Second, the “rough + fine” combination recognition method is used for contour extraction and connected component labeling of the restored image, and the target feature extraction time is reduced to one-third of traditional methods. Furthermore, the elliptical surface on the MOC is fitted by the least squares method (LSM), and the ellipse parameters (i.e., the center position, the long- and short-axes, and the deflection angle) are extracted. The accuracy of the target recognition is improved. Third, for the close-range measurement, based on the detected ellipse parameter, the pose of the noncooperative target is solved by the binocular imaging algorithm of the space circle; for the long-range measurement, the contour centroid of the target is calculated by the detected MOC, and the position of the target is solved by the LSM. Moreover, the effectiveness of the method is verified by the OpenSceneGraph numerical simulation system. Finally, an experimental system consisting of a binocular camera, a UR5 manipulator, and a satellite mockup was built. The experimental results verified the proposed method.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • The Optimal Distance Threshold for Fractional Frequency Reuse in
           Size-Scalable Networks
    • Authors: Seok-Ho Chang;Sang-Hyo Kim;Jihwan P. Choi;
      Pages: 527 - 546
      Abstract: In the fractional frequency reuse (FFR) system, the bandwidth is partitioned into orthogonal subbands such that users in the cell-center region use the subbands of a frequency reuse factor (FR factor) equal to 1, whereas users in the cell-edge region exploit the subbands of an FR factor larger than 1. The distance threshold, which is used to distinguish the cell-edge region from the cell-center region, is an important factor in FFR system performance. In this paper, we study the optimal distance threshold to maximize system throughput in the downlink cellular networks, including aerial base stations. Subject to the constraint that a given target outage probability is satisfied, the optimal distance threshold is analyzed as a function of the cell size. It is proven that when the sizes of all cells in the network are scaled at the same rate, the optimal distance threshold normalized by the cell size is nondecreasing in the cell size. The analytical results in this paper provide a system design guideline for initial planning of FFR cellular networks of different sizes, including macro, pico, and femto systems. In particular, for size-scalable aerial networks comprising base stations in the sky, such as balloons or unmanned aerial vehicles, our analysis offers insight into the design of the distance threshold with regard to the cell size.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Blind Star Identification Algorithm
    • Authors: Farshad Somayehee;Amir Ali Nikkhah;Jafar Roshanian;Sadegh Salahshoor;
      Pages: 547 - 557
      Abstract: In this paper, a new algorithm called blind star identification is presented to identify the stars in night sky images without using the intrinsic parameters of the star sensor camera (focal length, principal point, and pixel size), and in lost in space mode. The accuracy and reliability of the proposed algorithm were successfully validated by using the real night sky images and Monte Carlo simulations. Accordingly, the proposed algorithm was successfully able to identify in more than 90% of the images containing more than five stars and no wrong identification was observed in the Monte Carlo simulations. On the other hand, the rotation around the optical axis, which cannot be estimated using vector observations, should be minimized in the process of designing and manufacturing the star sensor and carefully measured in the ground calibration, like as the aberration and lens distortion. Ultimately, another advantage of this algorithm is the simultaneous use of planar and interstellar angles. This advantage leads to data redundancy and greater reliability of the algorithm so that the performance of the algorithm is guaranteed under severe error conditions.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Adaptive Subspace Signal Detection With Uncertain Partial Prior Knowledge:
           Off-Grid Problem and Efficient Implementation
    • Authors: Yuan Jiang;Hongbin Li;Muralidhar Rangaswamy;
      Pages: 558 - 571
      Abstract: We consider signal detection in subspace interference with partial prior knowledge of the subspace. The problem was recently considered by Li et al., where a subspace knowledge with learning (SKL) Bayesian model was proposed to leverage partial and uncertain knowledge of the subspace bases. The SKL, however, is based on the assumption that the subspace bases are a subset of a known overdetermined dictionary defined on a densely sampled frequency grid. Due to the so-called grid mismatch problem, i.e., the subspace bases may not be exactly on the frequency grid, there is a need to develop solutions that can exploit approximate prior knowledge, i.e., knowledge of frequency grid points close to the true frequencies but the latter themselves. In this paper, we extend the work by Li et al. and develop a modified SKL (mSKL) algorithm to exploit partial, approximate, and uncertain prior knowledge for subspace estimation and target detection. The mSKL is a Bayesian inference algorithm that can reject incorrect subspace bases, recover missing bases, and benefit approximately correct bases in the prior knowledge set. For computational efficiency, the recently introduced generalized approximate message passing (GAMP) is employed in the mSKL for efficient update of some posteriors. The resulting scheme, referred to as the mSKL-GAMP, is shown to offer competitive subspace recovery and target detection performance over a range of alternative methods in various scenarios with different grid mismatch levels.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • OFDM-MIMO Radar With Optimized Nonequidistant Subcarrier Interleaving
    • Authors: Gor Hakobyan;Michael Ulrich;Bin Yang;
      Pages: 572 - 584
      Abstract: Radar with digitally generated orthogonal frequency division multiplexing (OFDM) signals is an emerging research field that has been studied for the past few years. Another trend for radar is the multiple-input multiple-output (MIMO) architecture used for an efficient direction-of-arrival estimation. These two technologies can be efficiently combined into an OFDM-MIMO radar with novel interleaving concepts enabled by the multicarrier structure of OFDM. By multiplexing of transmit antennas via subcarrier interleaving, the whole bandwidth can be utilized by all transmit antennas simultaneously. In case of equidistant subcarrier interleaving, however, the unambiguously measurable distance range is reduced. To avoid this reduction, we propose an OFDM-MIMO radar concept with nonequidistant subcarrier interleaving (NeqSI) that maintains the full unambiguously measurable distance range. Since the NeqSI leads to sidelobes in distance estimation, we present an approach for generation of near-to-optimum nonequidistant interleaving patterns. To further complement the proposed concept, compressed sensing based distance-velocity estimation algorithm that achieves a high dynamic range in both distance and velocity dimensions is used. We study the performance of the presented concept in simulations and validate it by measurements with an OFDM-MIMO radar prototype.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Discrete-Time Sliding Mode Control for Deployment of Tethered Space Robot
           With Only Length and Angle Measurement
    • Authors: Zhiqiang Ma;Panfeng Huang;
      Pages: 585 - 596
      Abstract: This paper proposes a nonlinear discrete-time sliding mode based tension control for deployment of tethered space robot with only length and angle measurements. The discrete-time dynamics of deployment is uncovered based on discretization of Hamilton's principle. Taking into account the underactuated dynamics, the proposed discrete-time sliding surface can generate a specified reduced-order system, which can be regarded as an uncertain discrete-time system with multiple time delays, which is caused by a considerable sample interval, and the stability of a reduced-order system is well analyzed by combining a linear matrix inequation technique based on robust control theory and nonlinear discrete-time Lyapunov method. A novel input structure with the auxiliary variable sequence is presented to deal with the tension saturation, and the states can converge to the specified reduced-order system although the input saturation occurs. The proposed discrete-time method makes no appeal to velocity terms. It is cost-effective to use the proposed method for the information of length and angle are easily measured rather than that of velocity, and it conduces to low requirements for the measurement ability of sensors. Simulation results verify the stability analyses, and are coincident with the stability analyses.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Joint Exploitation of TDOA and PCL Techniques for Two-Dimensional Target
    • Authors: Augusto Aubry;Vincenzo Carotenuto;Antonio De Maio;Luca Pallotta;
      Pages: 597 - 609
      Abstract: This paper is focused on noncooperative target position estimation via the joint use of two-dimensional (2-D) hyperbolic and elliptic passive location techniques based on time difference of arrival (TDOA) and passive coherent locator (PCL) measurements, respectively. A fusion strategy is laid down at the signal processing level to obtain a reliable estimate of the current target position. With reference to the scenario with a single transmitter of opportunity, the mathematical model for joint exploitation of TDOA and PCL strategies is formulated. Then, the Cramer–Rao lower bound (CRLB) for the Cartesian coordinates of the target is established and the theoretical performance gains achievable over the localization technique using only TDOA or PCL observations are assessed. Finally, TDOA-PCL hybrid 2-D localization algorithms are provided and their performance in terms of root-mean-square error is compared with the square root of the CRLB.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Fault Isolation of Reaction Wheels for Satellite Attitude Control
    • Authors: Afshin Rahimi;Krishna Dev Kumar;Hekmat Alighanbari;
      Pages: 610 - 629
      Abstract: A new hierarchical method for fault detection, isolation, and identification of nonlinear systems with applications for in-orbit closed-loop controlled satellites is proposed where fault detection employs unscented Kalman filter and adaptive thresholds. Fault isolation employs multiple model approach in conjunction with Bayes' probability theorem and adaptive window, and fault identification employs dual state/parameter estimation using unscented Kalman filter. Results show up to 97% success rate under comprehensive Monte Carlo simulations for transient abrupt faults in satellite actuators.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • A Subspace Hybrid Integration Method for High-Speed and Maneuvering Target
    • Authors: Zegang Ding;Pengjie You;Lichang Qian;Xu Zhou;Siyuan Liu;Teng Long;
      Pages: 630 - 644
      Abstract: Long-time integration is an effective method to improve target detection performance in a noisy background. However, when detecting high-speed and maneuvering targets by long-time integration, it is easy to encounter the across range unit and across Doppler unit effects, which deteriorate the detection performance of algorithms with low computational complexity, such as moving target detection and hybrid integration (HI). The generalized Radon-Fourier transform (GRFT) detector has proven to have the best detection performance. However, the GRFT has a high computational burden for an ergodic search in a multidimensional motion parameter space and thus is hardly employed in real engineering applications. In this paper, we propose subspace HI (SHI) to achieve a good balance between detection performance and computational complexity. SHI first divides the parameter space into several equidimensional subspaces and moves them to the center of the coordinate system. Then, HI is implemented on all the subspaces, and all the HI results are finally fused. Through parameter space division and subspace movement, the values of the parameters in the subspaces are reduced, which increases the subaperture length, i.e., the time that the target echoes stay in one range-Doppler unit. By increasing the subaperture length, SHI gradually improves the detection performance with an increase in the computational complexity. Conversely, by shortening the subaperture length, the computational complexity of SHI can be reduced at the expense of the detection performance. Compared with HI and the GRFT, SHI achieves a better compromise between detection performance and computational complexity.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Extended State-Based Planning Approach for Deep Space Exploration
    • Authors: Hao Jin;Rui Xu;Wenming Xu;Shengying Zhu;
      Pages: 645 - 659
      Abstract: This paper deals with a new modeling method and a powerful planning approach for deep space probes. The key technique is based on the concept of extended state model. Furthermore, extended state model planning (ESMP) algorithm is designed to be fully compliant with the model, and flaw selection strategies are proposed to avoid redundant work. Finally, we discuss the time complexity of ESMP, and computational results comparing ESMP with the algorithm in Europa are presented.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Distributed Contact Plan Design for GNSSs
    • Authors: Zhibo Yan;Juan Andres Fraire;Kanglian Zhao;Hongcheng Yan;Pablo G. Madoery;Wenfeng Li;Hong Yang;
      Pages: 660 - 672
      Abstract: Next generation global navigation satellite systems (GNSSs) will embrace intersatellite links capability as an enabler of navigation and data transfer. However, platform restrictions will require of suitable contact plan design (CPD) schemes, which have been traditionally assumed centralized. After discussing the requirements of distributed CPD, we propose a first scheme in this class. Simulation results on the BeiDou GNSS prove that satisfactory metrics can be obtained enabling valuable and real autonomy for future GNSSs.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Bias CRLB in Sine Space for a Three-Dimensional Sensor
    • Authors: Michael Kowalski;Yaakov Bar-Shalom;Peter Willett;Djedjiga Belfadel;Fred Daum;
      Pages: 673 - 686
      Abstract: As bias estimation methods are developed, it becomes necessary to obtain the bound on bias estimation for more complex bias and sensor models. Three-dimensional (3-D) sensors, such as radars commonly used in applications, contain both scale and additive biases in sine space which result in a nonlinear estimation problem that may have poor observability and accuracy depending on the geometry of the sensors. By converting the sine space and range measurements to Cartesian using an unbiased conversion, it is possible, via creation of pseudomeasurements, to eliminate the need to estimate the target's state thereby reducing the sensor bias estimator complexity. The present paper evaluates the Cramér-Rao lower bound (CRLB) for estimating scale and additive biases in sine space for 3-D sensors and compares it with a maximum likelihood formulation implemented via iterated least squares, which is thereby shown to be statistically efficient. Additionally, the importance of measurement diversity is investigated with respect to the CRLB.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Joint Occlusion Detection and Phase Estimation Algorithm for Helicopter
           Satellite Communication
    • Authors: Haoge Jia;Zuyao Ni;Linling Kuang;Jianhua Lu;
      Pages: 687 - 697
      Abstract: In helicopter satellite communication systems, the received signal is blocked by the helicopter rotor blades during propagation, incurring the unstableness of traditional methods of channel estimation due to unknown channel state. To this end, a joint occlusion detection and phase estimation algorithm is proposed by factor graph in this paper. For occlusion detection to acquire channel state, the occlusion channel model is established relying on a Markov chain with a priori blocking ratio, in which the probability distribution of the channel state is calculated by the proposed message-passing algorithm. To obtain the occlusion position and update the blocking ratio, a cross-correlation method is designed. Furthermore, a joint block detection and phase estimation algorithm is developed based on the proposed occlusion detection algorithm to realize phase estimation by iterative receiver, where occlusion detection, phase estimation, and decoding are performed in turn for one turbo iteration and the result of decoding is then sent back to the occlusion detection step for the next iteration. Simulation results show that the proposed algorithm is adaptive to the dynamical change in the blocking ratio and can achieve bit error rate performance that is close to the performance bounds based on perfect channel state.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Wind Compensation Framework for Unpowered Aircraft Using Online Waypoint
    • Authors: Namhoon Cho;Suwon Lee;Jinrae Kim;Youdan Kim;Sanghyuk Park;Chanho Song;
      Pages: 698 - 710
      Abstract: This study presents a method to adjust the waypoints of an unpowered air vehicle to compensate for the influence of wind on the trajectory. A framework combining preflight waypoint planning and inflight waypoint adjustment is proposed. In the offline planning phase, optimal trajectories under various wind profile combinations are generated by using a direct optimization method. Waypoints are extracted from the obtained trajectories for each wind condition. Then, deviations of each waypoint due to wind from the corresponding waypoint on the trajectory for a zero-wind case are obtained; these deviations are used to construct the models of waypoint deviation as functions of wind speed and direction via least-squares regression. In the online adjustment phase, the wind-compensated waypoint is computed using the waypoint deviation model and the estimated wind velocity. A nonlinear six degrees-of-freedom simulation, incorporating a guidance and control system and a realistic wind profile, is performed to demonstrate the effectiveness of the proposed waypoint management framework.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Capturability of 3D PPN Against Lower-Speed Maneuvering Target for Homing
    • Authors: Ke-Bo Li;Hyo-Sang Shin;Antonios Tsourdos;Min-Jea Tahk;
      Pages: 711 - 722
      Abstract: The capturability of the two-dimensional (2-D) pure proportional navigation (PPN) guidance law against lower speed arbitrarily maneuvering target for homing phase had been thoroughly analyzed by using the nonlinear output regulation (NOR) method before. However, due to the complexity of the 3-D relative kinematics, the NOR method has not been applied to the capturability analysis of the 3-D PPN, which leads to the capturability discrepancy of the 2-D PPN and its 3-D extension. Thanks to the 3-D relative kinematic equation between the missile and target established in the rotating line-of-sight coordinate system, the capturability of the 3-D PPN against the lower speed arbitrarily maneuvering target for the homing phase is restudied by extending the NOR method of the 2-D PPN to the 3-D space. The necessary and sufficient condition for the missile guided by the 3-D PPN to intercept this type of target is obtained. It is proven that the capturability of the 3-D PPN is identical with that of the 2-D PPN.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Dual-Satellite Geolocation With Ephemeris Correction and Uncertainty
    • Authors: Jeroen L. Geeraert;Jay W. McMahon;
      Pages: 723 - 735
      Abstract: In this paper, we demonstrate that the uncertainty of the dual-satellite ephemeris must be included in order for the geolocation covariance to be accurate. Without the inclusion of this additional error source, the covariance is no longer consistent with the true uncertainty and can convey misleading results. The larger the uncertainty associated with the dual-satellite ephemeris the larger the geolocation covariance becomes. Therefore, we first demonstrate a technique for improving the dual-satellite ephemeris knowledge by using calibrator transmitters for orbit determination. Second, we derive a consider batch filter, which computes the best estimate of position of the unknown radio frequency source while taking into account the dual-satellite ephemeris uncertainty. An algorithm is also proposed for adding a probabilistic altitude constraint, which significantly reduces the solution error. Finally, we briefly touch upon a technique that allows for the dual-satellite ephemeris and source position to be estimated simultaneously thereby maintaining the correlations and optimality. All algorithms introduced have since been applied to real-world data and conveys actual capabilities rather than a theoretical approach alone.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Optimized Design and Thermal Analysis of Printed Magnetorquer for Attitude
           Control of Reconfigurable Nanosatellites
    • Authors: Muhammad Rizwan Mughal;Hassan Ali;Anwar Ali;Jaan Praks;Leonardo M. Reyneri;
      Pages: 736 - 747
      Abstract: An attitude control system (ACS) is one of the critical subsystems of any spacecraft and typically is in charge of de-tumbling, controlling, and orienting the satellite after initial deployment and during the satellite operations. The magnetorquer is a core magnetic attitude control actuator and, therefore, a good choice for nanosatellite attitude stabilization. There are various methods to achieve control torque using the magnetorquer. An innovative design of a printed magnetorquer has been proposed for the nanosatellites, which is modular, scalable, cost effective, less prone to failure, with reduce harness and power consumption since the traces are printed either on the top layer or inner layers of the printed circuit board. The analysis in terms of generated torque with a range of input applied voltages, trace widths, outer and inner-most trace lengths is presented to achieve the optimized design. The optimum operating voltage is selected to generate the desired torque while optimizing the torque to the power ratio. The results of the analysis in terms of the selection of optimized parameters, including torque to power ratio, generated magnetic dipole moment, and power consumption, have been validated practically on a CubeSat panel. The printed magnetorquer configuration is modular which is useful to achieve mission level stabilization requirements. For spin-stabilized satellites, the rotation time analysis has been performed using the printed magnetorquer.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Vibration Measurement Method for Artificial Structure Based on MIMO
           Imaging Radar
    • Authors: Weiming Tian;Yuqi Li;Cheng Hu;Yuanhao Li;Jingyang Wang;Tao Zeng;
      Pages: 748 - 760
      Abstract: Measuring the vibrating states of an artificial structure is an important approach to monitor the stability of the structure. However, the existing radar vibration measurement methods do not have enough azimuth resolution for measuring the vibrations in a relatively large scene, which contains multiple buildings or a large building. For such application scene, this paper proposes a vibration measurement method based on multiple-input multiple-output imaging radar system, which can achieve high azimuth resolution. Features of the proposed method are threefold: first of all, by utilizing the ability of quickly acquiring imaging data, the proposed method can achieve vibration measurement for the entire area simultaneously; second, in order to detect the positions of vibrating objects and decrease the time of vibration parameter estimation part, this paper proposes vibration similarity index to quantify the similarity between the detected signal and ideal vibration signal; at last, due to the limitations of the hardware performance, this paper adopts multiple signal classification least-squares estimation method to estimate the vibrating frequency and amplitude. To evaluate the performance of the proposed method, ideal point target simulation and vibrating calibrator experiment have been conducted, and the results show that the positions and the vibrating parameters of the vibrating objects fit well with the reference values. In addition, car experiment and bridge experiment have been carried out to verify the ability of the proposed method to measure the vibration of real artificial structures, which cannot be seen as point targets.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Network Coding Function for Converged Satellite–Cloud Networks
    • Authors: Tan Do-Duy;M. Ángeles Vázquez-Castro;
      Pages: 761 - 772
      Abstract: We tackle the problem of enhancing mobile ad-hoc networks (MANETs) coverage for emergency applications assisted by converged satellite-cloud networks. We propose the use of per-flow network coding (NC), which is provided by a NC function (NCF). We define NCFs with inputs available under 5G device-to-device assumption. Outputs are optimal coding rates balancing per-node computational resources and resulting coverage. Simulations show that our solution not only makes connectivity possible but also provides significant gains with respect to routing.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Optimization of Multiple Debris Removal Missions Using an Evolving Elitist
           Club Algorithm
    • Authors: Haiyang Li;Hexi Baoyin;
      Pages: 773 - 784
      Abstract: Space debris has become a great threat to space activities. We study and optimize space missions to remove multiple space debris. These missions are efficient and economical in stabilizing the orbital environment. In this paper, we propose an intelligent global optimization algorithm named the evolving elitist club algorithm (EECA), and we study its application in multiple debris removal missions. The crucial design element of EECA is the elitist club, which is a population created using ant colony optimization (ACO) and then evolved using genetic algorithm operators. We describe two types of multiple debris removal missions: 1) single spacecraft removal mission; and 2) multiple spacecraft removal mission. We optimize them using EECA. The proposed algorithm is compared with the conventional tree search method and other ACO algorithms. We show that EECA is more efficient than other algorithms. Furthermore, a time distribution (TD) EECA is proposed to handle time-dependent problems, and the time-continuous update mechanism of time-varying pheromone in TD EECA presents a novel idea for combinatorial-continuous problems.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Reduced Dimension STAP Based on Sparse Recovery in Heterogeneous Clutter
    • Authors: Wei Zhang;Ruixue An;Ningyu He;Zishu He;Huiyong Li;
      Pages: 785 - 795
      Abstract: For airborne-phased array radar systems, space-time adaptive processing (STAP) is supposed to be a crucial technique for improving target detection performance in the strong clutter background. However, practical application environments are always heterogeneous and have offered a severe challenge to the implementation of STAP. To address this reality, a data-dependent reduced dimension STAP approach based on sparse recovery (SR) is proposed in this paper. To take a full account of the heterogeneous environments, we consider the extremely heterogeneous case in which only one single snapshot is available. There is no doubt that, compared with the clutter covariance matrix (CCM) calculated directly by a single snapshot, the SR technique can provide a more accurate estimate. However, we should come to realize that this estimation is not accurate enough to adaptive processing according to the presented simulation results in lots of literature, and it has been demonstrated that the performance of traditional SR-based STAP degrades dramatically when only a snapshot is available. In the proposed approach, the CCM estimated by SR technique is utilized to design the reduced dimension transformation matrix rather than to calculate adaptive weights as the traditional SR-based STAP. The relatively accurate CCM can provide better support for the design of reduced dimension transformation matrix. From the simulation results, the proposed approach can achieve great performance of clutter suppression and target detection with only a single snapshot compared with several typical STAP algorithms. It is worthwhile pointing out that the proposed approach can also be applied when multiple snapshots are available and the performance improves with increasing number of available snapshots.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Nonlinear Autopilot Design for Endo- and Exoatmospheric Interceptor With
           Thrust Vector Control
    • Authors: Ju-Hyeon Hong;Chang-Hun Lee;
      Pages: 796 - 810
      Abstract: This paper proposes an autopilot design for an interceptor with thrust vector control that operates in the endo- and exoatmospheric regions. The main objective of the proposed autopilot design is to ensure control performance in both atmospheric regions, without changing the control mechanism. In this paper, the characteristics of the aerodynamic forces in both atmospheric regions are first investigated to examine the issue of the conventional control mechanism at various altitudes. And then, a control mechanism, which can be applied to both atmospheric regions, is determined based on the analysis results. An autopilot design is then followed by utilizing the control mechanism and the feedback linearization control method. Accordingly, the proposed autopilot does not rely on changing the control mechanism depending on flight condition unlike the conventional approach, however it can adjust the control gains automatically according to the changes in flight operating conditions. In this paper, the robustness of the proposed autopilot is investigated through the tracking error analysis and the relative stability analysis in the presence of model uncertainties. The physical meaning of the proposed autopilot is also presented by comparing to the well-known three-loop control structure. Finally, numerical simulations are performed to show the performance of the proposed method.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Serial Plackett Fusion for Decision Making
    • Authors: S. Hamed Javadi;Abdolreza Mohammadi;Alfonso Farina;
      Pages: 811 - 816
      Abstract: In serial wireless sensor networks, nodes send their compact information (decisions) to a fusion center via multihop. Each node performs data fusion and transmits the result. We propose using the Plackett copula for resolving the correlation in heterogeneous serial networks. The proposed scheme improves detection performance with low computation burden.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • A Sparse Approach for Identification of Signal Constellations Over
           Additive Noise Channels
    • Authors: Berkan Dulek;
      Pages: 817 - 822
      Abstract: Identification of unknown linear modulations over arbitrary additive noise channels is addressed within the framework of sparse linear regression. A regularized least squares problem with a sparsity inducing penalty is formulated to estimate the distribution of the transmitted symbols, which complete characterizes the underlying signal constellation. Separable and iterative algorithms that deliver reduced computational complexity are obtained based on the majorization-minimization framework. The proposed method can be employed to construct a modulation dictionary tailored to the target communications system before performing hypothesis testing-based classification.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Lossless Wideband RF Compression via Lifting-Based IIR Subband
    • Authors: Charles Cooper;Michael Marcellin;
      Pages: 823 - 829
      Abstract: This correspondence presents a scheme for the lossless compression of wideband spectrally and/or temporally sparse radio-frequency intercepts. It decomposes intercepts into time/frequency partitions using an adaptive invertible channelizer based on infinite impulse response orthogonal wavelet filter banks. The resulting subband decomposition is compressed via arithmetic coding.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
  • Sparse Equalization in Aeronautical Telemetry Using Two Transmit Antennas
    • Authors: Md. Shah Afran;Mohammad Saquib;Michael Rice;
      Pages: 830 - 836
      Abstract: This correspondence explores the application of sparse equalizers in generalized time-reversed space-time block codes (GTR-STBCs) for a two-transmit/one-receive antenna aeronautical telemetry link. It is shown that the jointly optimum design of the sparse equalizer coefficients and the power sharing parameter ρ in GTR-STBCs is computationally challenging because the active tap ratio of the sparse equalizers is a non-convex function of ρ. A search algorithm based on a grid search followed by an interpolation is shown to yield impressive results. Our numerical results demonstrate that depending on signal-to-noise ratio and channel conditions, the number of non-zero taps of sparse equalizers for GTR-STBCs can be reduced by 53% to 86% at the cost of 0.25 dB relaxation in the mean-squared error.
      PubDate: Feb. 2020
      Issue No: Vol. 56, No. 1 (2020)
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Heriot-Watt University
Edinburgh, EH14 4AS, UK
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