Evaluation of 5G Positioning Performance Based on UTDoA, AoA and Base-Station Selective Exclusion

Accurate and reliable positioning solution is an important requirement for many applications, for instance, emergency services and vehicular-related use cases. Positioning using cellular signals has emerged as a promising solution in Global Navigation Satellite System (GNSS) challenging environments, such as deep urban canyons. However, harsh working conditions of urban scenarios, such as with dense multipath and Non-Line of Sight (NLoS), remain as one of the key factors causing the detriment of the positioning estimation accuracy. This paper demonstrates that the use of joint Uplink Time Difference of Arrival (UTDoA) and Angle of Arrival (AoA) gives a significant improvement in the position accuracy thanks to the use of antenna arrays. The new advances of this technology enable more accurate user locations by exploiting angular domains of propagation channel in combination with time measurements. Moreover, it is shown that a better localization is achieved by combining the joined UTDoA and AoA with a base-station selective exclusion method that is able to detect and eliminate measurements affected by NLoS. The proposed approach has been tested through simulations based on a deep urban deployment map, which comes with an experimental data file of the user’s position. A sounding reference signal of 5G new radio operating in the centimeter-wave band is used. The obtained results add value to the use of advance antennas in 5G positioning. In addition, they contribute towards the fulfillment of high-accuracy positioning requirements in challenging environments when using cellular networks.

Download Full-text

Investigating the Benefits of Vector-Based GNSS Receivers for Autonomous Vehicles under Challenging Navigation Environments

Signals ◽

10.3390/signals1020007 ◽

2020 ◽

Vol 1 (2) ◽

pp. 121-137

Author(s):

Haidy Y. F. Elghamrawy ◽

Mohamed Tamazin ◽

Aboelmagd Noureldin

Keyword(s):

Autonomous Vehicles ◽

Tracking System ◽

Satellite System ◽

Velocity Estimation ◽

Estimation Accuracy ◽

Positioning Accuracy ◽

Gps Receivers ◽

Car Industry ◽

Vector Tracking ◽

Global Navigation Satellite

There is a growing demand for robust and accurate positioning information for various applications, including the self-driving car industry. Such applications rely mainly on the Global Navigation Satellite System (GNSS), including the Global Positioning System (GPS). However, GPS positioning accuracy relies on several factors, such as satellite geometry, receiver architecture, and navigation environment, to name a few. In urban canyons in which there is a significant probability of signal blockage of one or more satellites and/or interference, the positioning accuracy of scalar-based GPS receivers drastically deteriorates. On the other hand, vector-based GPS receivers exhibit some immunity to momentary outages and interference. Therefore, it is becoming necessary to consider vector-based GPS receivers for several applications, especially safety-critical applications, including next-generation navigation technologies for autonomous vehicles. This paper investigates a vector-based receiver’s performance and compares it to its scalar counterpart in signal degraded conditions. The realistic simulation experiments in this paper are conducted on GPS L1 C/A signals generated using the SpirentTM simulation system to create a fully controlled environment to examine and validate the performance. The results show that the vector tracking system outperforms the scalar tracking in terms of position and velocity estimation accuracy in signal-degraded environments.

Download Full-text

Unsupervised Human Detection with an Embedded Vision System on a Fully Autonomous UAV for Search and Rescue Operations

Sensors ◽

10.3390/s19163542 ◽

2019 ◽

Vol 19 (16) ◽

pp. 3542 ◽

Cited By ~ 15

Author(s):

Eleftherios Lygouras ◽

Nicholas Santavas ◽

Anastasios Taitzoglou ◽

Konstantinos Tarchanidis ◽

Athanasios Mitropoulos ◽

...

Keyword(s):

Embedded System ◽

Emergency Services ◽

Vision System ◽

Open Water ◽

Satellite System ◽

Search And Rescue ◽

Human Detection ◽

Primary Role ◽

Wide Range ◽

Global Navigation Satellite

Unmanned aerial vehicles (UAVs) play a primary role in a plethora of technical and scientific fields owing to their wide range of applications. In particular, the provision of emergency services during the occurrence of a crisis event is a vital application domain where such aerial robots can contribute, sending out valuable assistance to both distressed humans and rescue teams. Bearing in mind that time constraints constitute a crucial parameter in search and rescue (SAR) missions, the punctual and precise detection of humans in peril is of paramount importance. The paper in hand deals with real-time human detection onboard a fully autonomous rescue UAV. Using deep learning techniques, the implemented embedded system was capable of detecting open water swimmers. This allowed the UAV to provide assistance accurately in a fully unsupervised manner, thus enhancing first responder operational capabilities. The novelty of the proposed system is the combination of global navigation satellite system (GNSS) techniques and computer vision algorithms for both precise human detection and rescue apparatus release. Details about hardware configuration as well as the system’s performance evaluation are fully discussed.

Download Full-text

Low-cost, high accuracy Global Navigation Satellite System positioning for understanding floods

10.5194/egusphere-egu2020-8446 ◽

2020 ◽

Author(s):

Hessel Winsemius ◽

Andreas Krietemeyer ◽

Kirsten Van Dongen ◽

Ivan Gayton ◽

Frank Annor ◽

...

Keyword(s):

Global Navigation Satellite System ◽

Low Cost ◽

Smart Phone ◽

Satellite System ◽

Base Station ◽

Navigation Satellite ◽

Low Resource Settings ◽

Low Resource ◽

Global Navigation ◽

Global Navigation Satellite

<p>Detailed elevation is a prerequisite for many hydrological applications. To name a few, understanding of urban and rural flood hazard and risk; understanding floodplain geometries and conveyance; and monitoring morphological changes. The accuracy of traditional Global Navigation Satellite System (GNSS) chipsets in smart phones is typically in the order of several meters, too low to be useful for such applications. Structure from Motion photogrammetry methods or Light Detection and Ranging (LIDAR), may be used to establish 3D point clouds from drone photos or lidar instrumentation, but even these require very accurate Ground Control Point (GCP) observations for a satisfactory result. These can be acquired through specialised GNSS rover equipment, combined with a multi-frequency GNSS base station or base station network, providing a Real-Time (RTK) or Post-Processing Kinematics (PPK) solution. These techniques are too expensive and too difficult to maintain for use within low resource settings and are usually deployed by experts or specialised firms.</p><p>Here we investigate if accurate positioning (horizontal and vertical) can be acquired using a very recently released low-cost multi-constellation dual-frequency receiver (ublox ZED-F9P), connected with a simple antenna and a smart phone. The setup is remarkably small and easy to carry into the field. Using a geodetic (high-grade) GNSS antenna and receiver as base station, initial results over baselines in the order of a few km with the low-cost receiver revealed a positioning performance in the centimeter domain. Currently, we are testing the solution using a smart phone setup as base station within Dar es Salaam, to improve elevation mapping within the community mapping project &#8220;Ramani Huria&#8221;. We will also test the equipment for use in GCP observations within the ZAMSECUR project in Zambia and TWIGA project in Ghana. This new technology opens doors to affordable and robust observations of positions and elevation in low resource settings.</p>

Download Full-text

Impact on Antijamming Performance of Channel Mismatch in GNSS Antenna Arrays Receivers

International Journal of Antennas and Propagation ◽

10.1155/2016/1909708 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Zukun Lu ◽

Junwei Nie ◽

Feiqiang Chen ◽

Gang Ou

Keyword(s):

Transfer Function ◽

Global Navigation Satellite System ◽

Antenna Arrays ◽

Group Delay ◽

Satellite System ◽

Navigation Satellite ◽

Amplitude Wave ◽

Channel Mismatch ◽

Global Navigation Satellite ◽

The Impact

The performance of antijamming is limited by channel mismatch in global navigation satellite system (GNSS) antenna arrays receivers. Only when the amplitude and phase characteristics of each array channels are the same is the interference likely to be completely suppressed. This paper analyzes the impact on antijamming performance of channel mismatch. We built the model of channel mismatch and derived the impact on transfer function with space-time adaptive processor (STAP) of channel mismatch in theory. The impact factor of channel mismatch is proposed by the fuzzy transfer function, which could directly reflect the antijamming performance under channel mismatch. In addition, every characteristic in the channel mismatch model is analyzed. The analysis results show that the greatest impacts on antijamming performance are the range of amplitude wave and the group delay bias, while the influence of the number of amplitudes is next. As for the effect of group delay fluctuation is the smallest.

Download Full-text

Control System Architecture for Automatic Recovery of Fixed-Wing Unmanned Aerial Vehicles in a Moving Arrest System

Journal of Intelligent & Robotic Systems ◽

10.1007/s10846-021-01521-z ◽

2021 ◽

Vol 103 (4) ◽

Author(s):

Kristoffer Gryte ◽

Martin L. Sollie ◽

Tor Arne Johansen

Keyword(s):

Unmanned Aerial Vehicles ◽

Low Cost ◽

Field Testing ◽

Satellite System ◽

Base Station ◽

Research Literature ◽

Aerial Vehicles ◽

Global Navigation Satellite ◽

The Right ◽

Automatic Recovery

AbstractAutomatic recovery is an important step in enabling fully autonomous missions using fixed-wing unmanned aerial vehicles (UAVs) operating from ships or other moving platforms. However, automatic recovery in moving arrest systems is only briefly studied in the research literature, and is not yet an option when using low-cost, commercial off-the-shelf (COTS) autopilots. Acknowledging the reliability and low cost of COTS avionics, this paper adds recovery functionality as a modular extension based on non-intrusive additions to an autopilot with very general assumptions on its interface. This is achieved by line-of-sight guidance, which sends an augmented desired position to the autopilot, to ensure line-following along a virtual runway that guides the UAV into the arrest system. The translation and rotation of this line is determined by the pose of the arrest system, determined using two Global Navigation Satellite System (GNSS) receivers, where one is configured as a Real-Time Kinematic (RTK) base station. The relative position of the UAV and arrest system is also precisely estimated using RTK GNSS. Through extensive field testing, on two different fixed-wing UAVs, the system has shown its performance and reliability; 43 recovery attempts in a stationary net hit 0.01 ± 0.25m to the right and 0.07 ± 0.20m below the target in calm conditions. Further, 15 recoveries in a barge-mounted, ship-towed net hit 0.06 ± 0.53m to the right and 0.98 ± 0.27m below the target in winds up to 4 m/s. The remaining error is largely systematic, caused by communication delays, and could be reduced with more integral effect or through direct compensation.

Download Full-text

Determining the optimal site location of GNSS base stations

Boletim de Ciências Geodésicas ◽

10.1590/s1982-21702012000100009 ◽

2012 ◽

Vol 18 (1) ◽

pp. 154-169 ◽

Cited By ~ 9

Author(s):

Jen-Yu Han ◽

Yu Wu ◽

Rou-Yu Liu

Keyword(s):

Integrated Approach ◽

Satellite System ◽

Base Station ◽

Base Stations ◽

Relative Positioning ◽

Site Location ◽

Efficient Manner ◽

Global Navigation Satellite ◽

The Impact ◽

Optimal Site

The relative positioning technique plays an essential role in Global Navigation Satellite System (GNSS) surveys. Simultaneous observation at base and rover stations eliminates the majority of error sources thus the quality of a positioning solution can be substantially improved. However, topographic obstruction is still a key issue affecting positioning quality. In this study, an integrated approach for analyzing the impact of topographic obstruction on GNSS relative positioning has been developed. By considering varied satellite geometry according to actual terrain variation, this approach can be used to realistically determine satellite visibility condition for a specific base station with respect to any rover station. Furthermore, a base station quality index (BSQI) is proposed as an explicit indication of the sufficiency in a relative positioning. By incorporating the proposed approach, one can immediately identify an optimal site location for a GNSS base station with subsequent GNSS field survey thus achieved in a more reliable and cost-efficient manner.

Download Full-text

A Low-Cost Global Navigation Satellite System Positioning Accuracy Assessment Method for Agricultural Machinery

Applied Sciences ◽

10.3390/app12020693 ◽

2022 ◽

Vol 12 (2) ◽

pp. 693

Author(s):

Dorijan Radočaj ◽

Ivan Plaščak ◽

Goran Heffer ◽

Mladen Jurišić

Keyword(s):

Global Navigation Satellite System ◽

Accuracy Assessment ◽

Low Cost ◽

Satellite System ◽

Base Station ◽

Navigation Satellite ◽

Agricultural Machinery ◽

Positioning Accuracy ◽

Global Navigation ◽

Global Navigation Satellite

The high-precision positioning and navigation of agricultural machinery represent a backbone for precision agriculture, while its worldwide implementation is in rapid growth. Previous studies improved low-cost global navigation satellite system (GNSS) hardware solutions and fused GNSS data with complementary sources, but there is still no affordable and flexible framework for positioning accuracy assessment of agricultural machinery. Such a low-cost method was proposed in this study, simulating the actual movement of the agricultural machinery during agrotechnical operations. Four of the most commonly used GNSS corrections in Croatia were evaluated in two repetitions: Croatian Positioning System (CROPOS), individual base station, Satellite-based Augmentation Systems (SBASs), and an absolute positioning method using a smartphone. CROPOS and base station produced the highest mean GNSS positioning accuracy of 2.4 and 2.9 cm, respectively, but both of these corrections produced lower accuracy than declared. All evaluated corrections produced significantly different median values in two repetitions, representing inconsistency of the positioning accuracy regarding field conditions. While the proposed method allowed flexible and effective application in the field, future studies will be directed towards the reduction of the operator’s subjective impact, mainly by implementing autosteering solutions in agricultural machinery.

Download Full-text

Spatial Characterization of GNSS Multipath Channels

International Journal of Antennas and Propagation ◽

10.1155/2012/236464 ◽

2012 ◽

Vol 2012 ◽

pp. 1-15 ◽

Cited By ~ 4

Author(s):

Hatef Keshvadi ◽

Ali Broumandan ◽

Gérard Lachapelle

Keyword(s):

Fading Channels ◽

Multipath Fading ◽

Satellite System ◽

Handheld Devices ◽

Angle Of Arrival ◽

Multipath Fading Channel ◽

Coherent Integration ◽

Global Navigation Satellite ◽

Beamforming Technique

There is a growing interest in detecting and processing Global Navigation Satellite System (GNSS) signals in indoors and urban canyons by handheld devices. To overcome the signal attenuation problem in such adverse fading environments, long coherent integration is normally used. Moving the antenna arbitrarily while collecting signals is generally avoided as it temporally decorrelates the signals and limits the coherent integration gain. This decorrelation is a function of the antenna displacement and geometry of reflectors and angle of arrival of the received signal. Hence, to have an optimum receiver processing strategy it is crucial to characterize the multipath fading channel parameters. Herein, Angle of Arrival (AoA) and Angle Spread (AS) along with signal spatial correlation coefficient and fading intensity in GNSS multipath indoor channels are defined and quantified theoretically and practically. A synthetic uniform circular array utilizing a right-hand circular polarized (RHCP) antenna has been used to measure the spatial characteristics of indoor GNSS fading channels. Furthermore, rotating effect of a circular polarized antenna on the synthetic array processing and AoA estimation has been characterized. The performance of the beamforming technique via array gain is also assessed to explore the advantages and limitations of beamforming in fading conditions.

Download Full-text

Delineation of Agricultural Drainage Pipe Patterns Using Ground Penetrating Radar Integrated with a Real-Time Kinematic Global Navigation Satellite System

Agriculture ◽

10.3390/agriculture8110167 ◽

2018 ◽

Vol 8 (11) ◽

pp. 167 ◽

Cited By ~ 7

Author(s):

Barry Allred ◽

DeBonne Wishart ◽

Luis Martinez ◽

Harry Schomberg ◽

Steven Mirsky ◽

...

Keyword(s):

Real Time ◽

Global Navigation Satellite System ◽

Ground Penetrating Radar ◽

Satellite System ◽

Base Station ◽

Agricultural Drainage ◽

Navigation Satellite ◽

Drainage Pipe ◽

Global Navigation Satellite ◽

Ground Penetrating

Better methods are needed for mapping agricultural drainage pipe systems. Prior research on small test plots indicates that ground penetrating radar (GPR) is oftentimes capable of detecting buried drainage pipes; however, the feasibility of employing this geophysical technique in larger field areas has not been adequately evaluated. Ground penetrating radar integrated with a Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) may be an effective and efficient means of mapping drain lines within agricultural fields. Therefore, GPR-RTK/GNSS was tested in three agricultural settings; with Site 1 and Site 2 located in Beltsville, MD, USA and Site 3 near Columbus, OH, USA. Soils at the three sites ranged from silty clay loam to loamy sand. A GPR unit with 250 MHz antennas was used to detect drainage pipes, and at Sites 1 and 2, a physical GNSS base station was utilized, while a virtual base station was employed at Site 3. The GPR-RTK/GNSS configurations used in this study delineated a complex rectangular drainage pipe system at Site 1, with one set of drainage pipes oriented southwest-northeast and a second oriented southeast-northwest. At Site 2, a herringbone drain line pattern was outlined, and at Site 3, random drain lines were found. When integrated with RTK/GNSS, spiral or serpentine GPR transects (or spiral/serpentine segments of a GPR transects) were utilized to provide insight on drain line directional trends. Consequently, given suitable field conditions, GPR integrated with RTK/GNSS can be a valuable tool for farmers and drainage contractors needing to map subsurface drainage systems.

Download Full-text

Long Baseline Tightly Coupled DGNSS Positioning with Ionosphere-Free Inter-System Bias Calibration

Remote Sensing ◽

10.3390/rs13010067 ◽

2020 ◽

Vol 13 (1) ◽

pp. 67

Author(s):

Jianhua Cheng ◽

Chao Jiang ◽

Liang Li ◽

Chun Jia ◽

Bing Qi ◽

...

Keyword(s):

Satellite System ◽

Base Station ◽

Coupled Method ◽

Loosely Coupled ◽

Long Term Stability ◽

Long Baseline ◽

Positioning Method ◽

Tightly Coupled ◽

System Bias ◽

Global Navigation Satellite

Based on the statistical stability of the inter-system bias (ISB), we propose a tightly coupled Differential Global Navigation Satellite System (DGNSS) positioning method by using ionosphere-free combination for the long baseline applications. The proposed method is compatible with the traditional Radio Beacon (RBN) base station implementation. The tightly coupled DGNSS positioning method is utilized at the long baseline rover by eliminating the effect of ionosphere delay with ionosphere-free (IF) based differential ISB calibration. The improved positioning model strength can be obtained with the proposed method when compared with the traditional loosely coupled method, particularly under the satellite-deprived environment. GNSS datasets of different baselines were collected to test the proposed method. The results of the ISB stability show that the ISB has long-term stability and needs to be calibrated when the receiver is rebooted. The positioning results show that when compared with the IF-based loosely coupled method, the IF-based tightly coupled DGNSS method based on ISB calibration can obtain better positioning performance of accuracy and continuity within 240 km baselines.

Download Full-text