GDOP index in UWB indoor location system experiment

Global Positioning System (GPS) satellites signal processing to obtain all in view satellite measurements and to use them to find a solution and to do integrity monitoring forms a major component of the load on the receiver's processing element. If processing capability is limited there is restriction on the number of measurements which can be obtained and processed. Alternatively, the number of measurements can be restricted and the resulting saving in load on the processor can be used to offer more spare processing time which can be used for other user specific requirements. Thus if m visible satellites can provide measurements only n measurements can be used (n < m). The arrangement and the number of GPS satellites influence measurement accuracy. Dilution of Precision (DOP) is an index evaluating the arrangement of satellites. Geometric DOP (GDOP) is, in effect, the amplification factor of pseudo-range measurement errors into user errors due to the effect of satellite geometry. The GDOP approximation is an essential feature in determining the performance of a positioning system. In this paper, knowledge-based methods such as neural networks and evolutionary adaptive filters are presented for optimum approximation of GDOP. Without matrix inversion required, the knowledge-based approaches are capable of evaluating all subsets of satellites and hence reduce the computational burden. This would enable the use of a high-integrity navigation solution without the delay required for many matrix inversions. Models validity is verified with test data. The results are highly effective techniques for GDOP approximation.

The existing literatures usually adopt the linear method to obtain the location error which is usually evaluated by geometrical dilution of precision (GDOP) in nonlinear passive location systems. However, the linear method is not always suitable in any condition, and the obtained GDOP may deviate the true values of location errors severely when the location system is of severe nonlinearity. Thus, a new nonlinear method for the calculation of location Error based on unscented transformation (UT) is proposed and verified in this paper.

This paper presents a model to predict the GDOP value (Geometric Dilution of Precision) and the probability of its occurrence at a point in space and time using airborne LiDAR (Light Detection and Ranging) data and the ultra-rapid product (URP) available from the International GPS Service. LiDAR data help to classify the terrain around a GPS (Global Positioning System) receiver into categories such as ground, opaque objects, translucent objects and transparent regions as per their response to the transmission of GPS signal. Through field experiments it is established that URP can be used satisfactorily to determine GDOP. Further experiments have shown that the translucent objects (mainly trees here) lower the GDOP quality as they obstruct the GPS signal. LiDAR data density on trees is used as a measure of the translucency of trees to the GPS signal. Through GPS observations taken in field a relationship has been established between LiDAR data density on trees and the probability that a satellite which is behind the tree is visible at the GPS receiver. A model is presented which, for all possible combinations of visible satellites, computes the GDOP value along with the probability of occurrence of this GDOP. A few results are presented to show the performance of the model developed and its possible application in location based queries.

The traditional approach to both earthquake and Global Positioning System (GPS) location problems in a homogeneous half-space produces a nonlinear relationship between a set of known positions, seismic stations or GPS satellites, and an unknown point, an earthquake hypocenter or GPS receiver. Linearization, followed by an iterative inversion, is typically used to solve both problems. Although sources and receivers are swapped in the earthquake and GPS location problems, the obser- vation equation is the same for both, due to the principle of reciprocity. Consequently, the mechanical part of the solution of the equations is the same and single-step closed- form solutions for the GPS location problem, such as the Bancroft algorithm, can also be used to solve for earthquake hypocenters in a homogeneous half-space. This article applies the Bancroft algorithm to synthetic and real data for the Charlevoix seismic zone and compares the location of ∼1200 events estimated with both the Bancroft algorithm and HYPOINVERSE. The Bancroft algorithm shows quantifiable improve- ments in accuracy compared with traditional methods. We also show how tools com- monly used by the GPS community, such as the geometric dilution of precision, can be used to better estimate the precision of the results obtained by a seismic network.

In order to improve the accuracy and engineering feasibility of four-Satellite localization system, the frequency difference measurement is introduced to the four-Satellite TDOA (Time Difference of Arrival) localization algorithm. The TDOA/FDOA (Frequency Difference of Arrival) localization algorithm is used to optimize the GDOP (geometric dilution of precision) of four-Satellite localization. The simulation results show that the absolute position measurement accuracy has little influence on TDOA/FDOA localization accuracy as compared with TDOA localization. Under the same conditions, TDOA/FDOA localization has better accuracy and its GDOP shows more uniform distribution in diamond configuration case. The localization accuracy of four-Satellite TDOA/FDOA is better than the localization accuracy of four-Satellite TDOA.

Object positioning is a trending topic currently. The global positioning system (GPS) is the most common positioning method. Cars rely on GPS to navigate and plan routes to destinations. Unmanned aerial vehicles employ the GPS to assist flight and achieve cruise functions of automatic altitude and fixed point flights. However, the GPS fails when positioning is conducted indoors because GPS signals cannot be received indoors. Therefore, an indoor positioning system (IPS) should be used for indoor positioning. This paper mainly discusses the localization error of an ultra-wideband (UWB) indoor positioning system. A two-triangle positioning method was used to locate a target point separately through each triangle. Finally, values obtained using the two triangles were calculated using an algorithm to obtain a more accurate position.

The GPS (Global Positioning System) receiving antenna installation angle on a quasi-inertial orientation of the exploration-satellite is studied. Firstly, according to the mission requirements, the satellite attitude requirements are analyzed. Secondly, theoretical analysis and simulation were conducted according to the attitude requirements of posture on the installation of the GPS receiver antenna installation angle, preferably by the GDOP (Geometric Dilution of Precision) values. Finally, conclusion is drawn based on the simulation results that the GPS receiving antenna axial is near to the ± <em>y</em> axis of body reference frame, viz. the orbital plane normal or negative normal direction.

The new design and analysis presented in the paper are on an intelligent emergency location and response system that is specifically designed within the framework of university campuses, and one of the case studies is the deployment of the system on the Al-Ayen Iraqi University. The system network integrates a multi-sensor network with acoustic arrays, thermal cameras, smoke/ gas sensors, vibration sensors, and electrical fault chips, which work together with the extremely precise angle-of-arrival (AOA) research algorithms. The system is capable of working in a wireless ad-hoc sensor network and thus offers secure communication to ensure that the data integrity, confidentiality, and timely responsiveness can be reached, and avoid security problems like unauthorized access, data tampering, and signal interference. It is coded to identify, categorize, and locate any disaster, including fires, electrical outages, and collapses of the structure (among others), with the use of such techniques as the Multiple Signal Classification (MUSIC) algorithm and triangulation. Simulation and experimental findings were encouraging: the localization error of about 5 meters, detection latency of about 1 second, classification error of more than 97% and over 40% reduction in dispatch time. Security has also been put in place so that the system is not accessed accidentally and compromised, which is an aspect that renders the system a strong system in real-life situations. The system reduced the approximate dispatch time from between 120 seconds to approximately 75 seconds as opposed to the dependency on a printed circuit board (PCB) antenna. It has been demonstrated that the system has an availability of 99% over a 30-day period, and it has a high sensor failure resistance by Geometric Dilution of Precision (GDOP) testing and error confidence. An interface that offers real-time visualization of the events assists in the management of emergency response by providing the event that is taking place in the form of a graph to alert the responders.

In recent times, impulse-radio ultra-wideband (IR-UWB) systems have gained significant attention for indoor positioning and short-range radar applications due to many of their inherent properties like ultra-fine temporal resolution, non-line-of-sight detection, multipath immunity, low power consumption, low-cost, etc. The critical challenge for the IR-UWB based systems is to generate an IR-UWB pulse, which is shorter in time and higher in amplitude. In particular, for the indoor-ranging and radar applications, the limited peak power of an IR-UWB pulse restricts the line-of-sight (LOS) range, non-line-of-sight (NLOS) detection and degrades radar imaging. In this thesis, two levels of improvement are proposed and demonstrated. Firstly, an MMIC design is presented at the chip-level to achieve higher peak power directly from the chip. Secondly, novel beamforming techniques are proposed, which superimpose transmitted pulses spatially to produce strong radiating beams. Finally, the proposed beamforming networks are optimized and prototyped. The generation of the IR-UWB pulse is carried out through two successive stages on the MMIC, called as the impulse generator and the pulse former. The impulse generator generates a 7V sub-nanosecond voltage pulse, which is being used as an input to the pulse former stage. The pulse former performs the signal scaling, time-shifting, amplitude-reversal, and signal-addition to produce the desired Gaussian-enveloped multi-cycle IR-UWB pulse. The systematic circuit analysis is performed, and the effect of coupling capacitors on the amplification factor as well as impedance profile at each stage of pulse former are discussed in detail. In addition to this, the effect of temperature-dependent parasitic on the transient behaviour of the proposed IR-UWB pulse generator is analyzed, and the required mathematical model is derived. The proposed circuit is optimized for the highest possible output peak-power in the 3-5 GHz UWB band. The presented design is fully utilizing the existing 2 µm GaAs HBT cascode pair configuration, which significantly increases the output voltage swing while reducing the total power consumption. The measured output pulse has a peak-to-peak voltage of 10.2 V for a 50 Ω load. The proposed pulse generator MMIC has a total power consumption of 122 µW at 100 kHz pulse repetition frequency and power efficiency of 9.8% (18.4%). In order to further improve the peak power level in desired directions, the beam-pattern analysis of an electronically steerable multi-beam IR-UWB transmitter tag suited for real-time positioning systems is presented and demonstrated. Two linear arrays of four elements with an inter-element spacing of 18 cm and 10.2 cm are proposed and optimized. The array with a spacing of 10.2 cm is intentionally configured to produce orthogonal beams, which eventually provides better geometric dilution of precision (GDOP). The beam steering-angle analysis and an intensity table for the Gaussian-modulated multi-cycle IR-UWB beamforming array are provided. The proposed beamforming transmitter arrays are observed to achieve the scanning range from –60⁰ (–90⁰) to +60⁰ (+90⁰) with a scanning resolution of 5⁰ and 8⁰ in the measurements. In addition to this, a novel algorithm for the separation between distributed wireless sensor nodes of the virtual non-linear array is proposed for collaborative beamforming in the wireless sensor network system. The proposed algorithm can produce a single beam radiation pattern of the collaborative virtual radar array. The presented radiation pattern is proposed for Gaussian-shaped multi-cycle IR-UWB beamforming, which effectively reduces the grating lobes despite electrically large separation between the transmitting nodes. A random error of positioning for sensor nodes and random jitter for different IR-UWB pulse is incorporated in the analysis, and related simulation results are provided. A prototype for the time domain beam-pattern measurement is developed for proof-of-concept. The measurement results show better than 6dB suppression for side lobes radiation.

At present, location technology divides into outdoor location technology and indoor location technology. Comparing with other indoor location methods, ultra-wide band (UWB)indoor location technology has the advantages of strong anti-multipath interference ability and signal penetration ability. But, when this method faces large obstacles or metal obstacles, non line of sight (NLOS) will still occur. Indoor location system is a part of our project Home Care System for The Elderly. The NLOS of Indoor location system reduces the reliability of Home Care System for The Elderly. In order to improve the accuracy of location and efficiency of operation, an NLOS detection method based on k-nearest neighbors (KNN) algorithm is proposed. This algorithm modeled the training samples to find the K value with the highest recognition accuracy. The experimental results show that The NLOS detection accuracy of this method is 78% in the simulated apartment scene. With the same number of samples, the accuracy of the widely used Convolutional Neural Networks (CNN) algorithm is 67%. The experimental results show that KNN algorithm is more suitable for Home Care System for The Elderly for it can keep high accuracy with less requirement for the number of samples than CNN.

This paper describes a design effort in a smart tracking prototype, in an attempt to provide real-time, mobile and seamlessly indoor/outdoor location tracking for medical staff, patient or instruments in hospital environment, by integrating GPS (Global Position System) with UWB (Ultra Wideband). Ultra Wideband (UWB) technology can locate a person or asset to the accuracy of centimeters. While UWB technology is becoming popular for indoor position tracking, GPS technology has been around for some time for use in outdoor position tracking with an accuracy of 1 to 100 meters depending on the type of equipment used. It is envisaged that it is possible to combine GPS with UWB to give accurate position regardless of where the person or object is in indoor or outdoor. In view of the strong need for indoor-outdoor tracking in many environments such as hospitals, we looked into the possibility of integrating UWB and GPS to provide the target with seamless indoor-outdoor navigation capability and have developed a prototype. The system structure and experimental results will be illustrated in this paper. To our knowledge, no same system is reported yet.

Nowadays, it is becoming increasingly important to understand the multiple configuration factors of BLE anchors in indoor location systems. This task becomes particularly crucial in the context of activity recognition in multi-occupancy smart environments. Knowing the impact of the configuration of BLE anchors in an indoor location system allows us to distinguish the interactions performed by each inhabitant in a smart environment according to their proximity to each sensor. This paper proposes a new methodology, OBLEA, that determines the optimisation of Bluetooth Low Energy (BLE) anchors in indoor location systems, considering multiple BLE variables to increase flexibility and facilitate transferability to other environments. Concretely, we present a model based on a data-driven approach that considers configurations to obtain the best performing configuration with a minimum number of anchors. This methodology includes a flexible framework for the indoor space, the architecture to be deployed, which considers the RSSI value of the BLE anchors, and finally, optimisation and inference for indoor location. As a case study, OBLEA is applied to determine the location of ageing inhabitants in a nursing home in Alcaudete, Jaén (Spain). Results show the extracted knowledge related to the optimisation of BLE anchors involved in the case study.

High-precision indoor localization and tracking are essential requirements for the safe navigation and task execution of autonomous mobile robots. Despite the growing importance of mobile robots in various areas, achieving precise indoor localization remains challenging due to signal interference, multipath propagation, and complex indoor layouts. In this work, we present the first comprehensive study comparing the accuracy of Bluetooth low energy (BLE), WiFi, and ultra wideband (UWB) technologies for the indoor localization of mobile robots under various circumstances. In the performed experiments, the error margin of the WiFi-based systems reached 608.7 cm, which is not tolerable for most applications. As a commonly used technology in the existing tracking systems, the accuracy of BLE-based systems is at least 44.12% better than that of WiFi-based systems. The error margin of the BLE-based system in tracking static and mobile robots was 191.7 cm and 340.1 cm, respectively. The experiments showed that even with a limited number of UWB anchors, the system provides acceptable accuracy for tracking the mobile robots. Using only four UWB beacons in an environment of about 431 m2 area, the maximum error margin of detected positions by the UWB-based tracking system remained below 13.1 cm and 28.9 cm on average for the static and mobile robots, respectively. This error margin is 88.05% lower than that of the BLE-based system and 93.27% lower than that of the WiFi-based system on average. The high tracking precision, the need for a lower number of anchors, and the decreasing hardware costs point out that UWB will be the dominating technology in indoor tracking systems in the near future.

An indoor positioning system (IPS) is a technology employed to locate objects and people within a building scenario using signal processing or other sensory information. Ultra Wide Band (UWB) is a versatile wireless technology that can be employed as an IPS and has shown very good performances. UWB can be used in many scenarios and its effectiveness in through wall detection along with its excellent resolution for person localization is one of the best applications of Impulse Radio (IR) UWB. The main objective of this work is to propose a concept for intelligent radar systems employing UWB augmented by machine learning approaches to not only localize but understand the location of a person or target within a building. Although suitably developed UWB is excellent for obtaining localizing data it does not automatically understand what that location effectively means or where it is thus further methods are required to create meaningful data for end user appreciation. Learning from the huge amount of UWB signal data through Multi Class Support Vector Machine (MC-SVM) architecture enables a truly evolving scheme to both localize targets and identify them in a useful way. Statistical analysis of the experimental results supports the proposed algorithm.

This paper presents results of coexistence measurement studies between multiple ultra wideband (UWB) transmitters and a global positioning system (GPS). In addition, mathematical models for UWB aggregate noise rise in the GPS, universal mobile telecommunications system (UMTS) and wireless local area network (WLAN) 802.11a/g bands are illustrated. In GPS coexistence measurements, a realistic satellite constellation and outward circumstances were created using a commercial GPS simulator and receiver. Each measurement was carried out using Federal Communications Commission (FCC) compatible prototype singleband UWB transmitters. The measurements took place in an anechoic chamber to minimize any radio interference. The results clearly show that GPS can survive even under a large number of interfering UWB devices which are operating using realistic transmission parameters. Still, if a large number of interfering UWB devices or high UWB activity factor and pulse repetition frequency is used UWB can be regarded as a threat to GPS usage.