SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new stat...SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters,the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling small-scale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions (CDFs) for the three key channel impulse response (CIR) statistics.展开更多
The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Si...The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Since buildings are inherently elevated objects, these images need to be co-registered with their elevation data for reliable building detection results. However, accurate co-registration is extremely difficult for off-nadir VHR images acquired over dense urban areas. Therefore, this research proposes a Disparity-Based Elevation Co-Registration (DECR) method for generating a Line-of-Sight Digital Surface Model (LoS-DSM) to efficiently achieve image-elevation data co-registration with pixel-level accuracy. Relative to the traditional photogrammetric approach, the RMSE value of the derived elevations is found to be less than 2 pixels. The applicability of the DECR method is demonstrated through elevation-based building detection (EBD) in a challenging dense urban area. The quality of the detection result is found to be more than 90%. Additionally, the detected objects were geo-referenced successfully to their correct ground locations to allow direct integration with other maps. In comparison to the original LoS-DSM development algorithm, the DECR algorithm is more efficient by reducing the calculation steps, preserving the co-registration accuracy, and minimizing the need for elevation normalization in dense urban areas.展开更多
This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from ...This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.展开更多
In this paper,the method of extracting guidance information such as the line-of-sight(LOS)rates under the anti-infrared decoy state for the roll-pitch seeker is researched.Coordinate systems which are used to describe...In this paper,the method of extracting guidance information such as the line-of-sight(LOS)rates under the anti-infrared decoy state for the roll-pitch seeker is researched.Coordinate systems which are used to describe the angles transform are defined.The LOS angles reconstruction model of the roll-pitch seeker in inertial space is established.A Kalman filter model for extracting LOS rates of the roll-pitch seeker is proposed.In this model,the target performs constant acceleration(CA)model maneuvers.The error model of LOS rates extraction under infrared decoy state is established.Several existing methods of extracting LOS rates under anti-infrared decoy state are listed in this paper.Different from the existing methods,a novel method that uses extrapolated values of target accelerations as filter measurements is proposed to solve the guidance information extraction problem under the anti-infrared decoy state.Numerical simulations are conducted to verify the effectiveness of the proposed method under different target maneuvering models such as the CA model,the CA extended model and the singer model.The simulation results show that the proposed method of extracting guidance information such as LOS rates for the rollpitch seeker under the anti-infrared decoy state is effective.展开更多
This paper investigates the data collection in an unmanned aerial vehicle(UAV)-aided Internet of Things(IoT) network, where a UAV is dispatched to collect data from ground sensors in a practical and accurate probabili...This paper investigates the data collection in an unmanned aerial vehicle(UAV)-aided Internet of Things(IoT) network, where a UAV is dispatched to collect data from ground sensors in a practical and accurate probabilistic line-of-sight(LoS) channel. Especially, access points(APs) are introduced to collect data from some sensors in the unlicensed band to improve data collection efficiency. We formulate a mixed-integer non-convex optimization problem to minimize the UAV flight time by jointly designing the UAV 3D trajectory and sensors’ scheduling, while ensuring the required amount of data can be collected under the limited UAV energy. To solve this nonconvex problem, we recast the objective problem into a tractable form. Then, the problem is further divided into several sub-problems to solve iteratively, and the successive convex approximation(SCA) scheme is applied to solve each non-convex subproblem. Finally,the bisection search is adopted to speed up the searching for the minimum UAV flight time. Simulation results verify that the UAV flight time can be shortened by the proposed method effectively.展开更多
基金the Key Program of National Natural Science Foundation of China(Grant No.60432040).
文摘SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters,the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling small-scale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions (CDFs) for the three key channel impulse response (CIR) statistics.
文摘The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Since buildings are inherently elevated objects, these images need to be co-registered with their elevation data for reliable building detection results. However, accurate co-registration is extremely difficult for off-nadir VHR images acquired over dense urban areas. Therefore, this research proposes a Disparity-Based Elevation Co-Registration (DECR) method for generating a Line-of-Sight Digital Surface Model (LoS-DSM) to efficiently achieve image-elevation data co-registration with pixel-level accuracy. Relative to the traditional photogrammetric approach, the RMSE value of the derived elevations is found to be less than 2 pixels. The applicability of the DECR method is demonstrated through elevation-based building detection (EBD) in a challenging dense urban area. The quality of the detection result is found to be more than 90%. Additionally, the detected objects were geo-referenced successfully to their correct ground locations to allow direct integration with other maps. In comparison to the original LoS-DSM development algorithm, the DECR algorithm is more efficient by reducing the calculation steps, preserving the co-registration accuracy, and minimizing the need for elevation normalization in dense urban areas.
文摘This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.
基金supported by the Key Laboratory of Defense Science and Technology Foundation of Luoyang Electro-optical Equipment Research Institute(6142504200108)。
文摘In this paper,the method of extracting guidance information such as the line-of-sight(LOS)rates under the anti-infrared decoy state for the roll-pitch seeker is researched.Coordinate systems which are used to describe the angles transform are defined.The LOS angles reconstruction model of the roll-pitch seeker in inertial space is established.A Kalman filter model for extracting LOS rates of the roll-pitch seeker is proposed.In this model,the target performs constant acceleration(CA)model maneuvers.The error model of LOS rates extraction under infrared decoy state is established.Several existing methods of extracting LOS rates under anti-infrared decoy state are listed in this paper.Different from the existing methods,a novel method that uses extrapolated values of target accelerations as filter measurements is proposed to solve the guidance information extraction problem under the anti-infrared decoy state.Numerical simulations are conducted to verify the effectiveness of the proposed method under different target maneuvering models such as the CA model,the CA extended model and the singer model.The simulation results show that the proposed method of extracting guidance information such as LOS rates for the rollpitch seeker under the anti-infrared decoy state is effective.
基金supported by the National Key Research and Development Program under Grant 2022YFB3303702the Key Program of National Natural Science Foundation of China under Grant 61931001+1 种基金supported by the National Natural Science Foundation of China under Grant No.62203368the Natural Science Foundation of Sichuan Province under Grant No.2023NSFSC1440。
文摘This paper investigates the data collection in an unmanned aerial vehicle(UAV)-aided Internet of Things(IoT) network, where a UAV is dispatched to collect data from ground sensors in a practical and accurate probabilistic line-of-sight(LoS) channel. Especially, access points(APs) are introduced to collect data from some sensors in the unlicensed band to improve data collection efficiency. We formulate a mixed-integer non-convex optimization problem to minimize the UAV flight time by jointly designing the UAV 3D trajectory and sensors’ scheduling, while ensuring the required amount of data can be collected under the limited UAV energy. To solve this nonconvex problem, we recast the objective problem into a tractable form. Then, the problem is further divided into several sub-problems to solve iteratively, and the successive convex approximation(SCA) scheme is applied to solve each non-convex subproblem. Finally,the bisection search is adopted to speed up the searching for the minimum UAV flight time. Simulation results verify that the UAV flight time can be shortened by the proposed method effectively.
