TDOA Methods Research Articles

Determining the coordinates of a mobile robot in an industrial space using BLE technology based on RSSI data received from base stations

Existing global positioning technologies cannot be applied indoors, where the signal from satellites or communication towers is significantly reduced or completely absent due to signal weakening in the walls of the building. Wireless network technologies such as Bluetooth or Wi-Fi can also be used in the process of local determining the mobile platforms position in industrial premises. But such methods have a problem with providing the required accuracy. The relevance of these studies is associated with solving the problem of local positioning of mobile robots in a room with an accuracy of ten centimeters. The article presents a comparative analysis of determining coordinates’ principles by the AOA, TOA, TDOA and RSSI methods. It is proposed to use BLE technologies based on the RSSI data received from base stations. Using the triangulation method, formulas are obtained for solving the problem of determining the coordinates of an object moving in space. The software and hardware complex architecture has been developed. It is proposed to use ESP32 modules as base radio stations. The RSSI value is very unstable, so the positioning accuracy will depend on the number of base stations and the additional software tools used.

Mathematical model of geolocation of a satellite communication station using one relay satellite

At present, multi-satellite geolocation systems based on the TDOA are actively used to localization of radio emission sources in satellite communication systems operating via relay satellites without on-board processing. In General, information about the location of the radio emission sources is contained in the difference of the inclined range from the multiple fixed points with known coordinates. Such points of space in the classical geolocation system are two or more relay satellites in geostationary orbit. It is not always possible to have two or more satellites retransmitting the same signal. Therefore, it is necessary to develop a mathematical model for geolocation using a single relay satellite. Single-satellite geolocation is based on the use of Doppler, TDOA, or phase direction finding methods. With this approach, it is desirable that a single satellite has the ability to move in a controlled manner, either in altitude or at different speeds relative to its standing point. Moving the satellite along the equator in position and along the meridian in height allows you to calculate several orthogonal bases of estimates of the inclined range to the radio source. In this case, the determination of coordinates is based on the increment of the distance of the object's signal runs between the end points of each base. This provides the construction of position lines (hyperballs), the intersection of which is the source location. If the movement of the satellite along the equator and the meridian is performed with a change in speed, then geolocation is based on measurements of several orthogonal components of the Doppler frequency shift of the radio source signals. The base will be called two, four or more pairwise taken orbital positions of the satellite at points with fixed coordinates; S x y z1 1 1 1( , , ) S x y z2 2 2 2( , , ); S x y z2 2 2 2( , , ) S x y z3 3 3 3( , , ); etc. in all possible combinations. An arbitrary inclined base formed in the spacecraft orbit has an extension of Бп (x2  x1)2  (y2  y1)2  (z2  z1)2 . Differential range Дд = Дн2 – Дн1. To geolocate the M-object, you must: 1. Measure the difranges between M over two or more different shifted Дн bases at multiple satellite drift positions – Дд1, Дд2, ..., Дд4, etc. 2. Calculate the parameters al, bl, cl of each l-th hyperbolic surface of the section of the conic equations of the geometric location of the points of position M with the measured Дд1, Дд2, ..., Дд4 and the known Дн. Construct a common point of intersection of several such hyperbolic surfaces of the cross-section of the conic equations of the geometric location of the points of the position of the object M(x, y, z). The resulting vector of linear coordinates M(x, y, z) of the object must be converted from geocentric to geographical coordinates of the spherical coordinate system of the object M (longitude, latitude, Position-vector).

Accuracy Analysis of a Wireless Indoor Positioning System Using Geodetic Methods

Abstract Ubisense RTLS is one of the Indoor positioning systems using an Ultra Wide Band. AOA and TDOA methods are used as a principle of positioning. The accuracy of positioning depends primarily on the accuracy of determined angles and distance differences. The paper presents the results of accuracy research which includes a theoretical accuracy prediction and a practical test. Theoretical accuracy was calculated for two variants of system components geometry, assuming the parameters declared by the system manufacturer. Total station measurements were taken as a reference during the practical test. The results of the analysis are presented in a graphical form. A sample implementation (MagMaster) developed by Globema is presented in the final part of the paper.

Adaptive filtration of radio source movement parameters with complex use of sensor network data based on TDOA and RSS methods

The optimal and quasi-optimal adaptive algorithms for filtration of parameters of radio source movement with different kinds of maneuvers have been synthesized on the basis of mathematical tools of discrete-time mixed Markov processes. These algorithms involve the complex use of sensor network data obtained on the basis of the TDOA and RSS methods. The devices implementing the above algorithms are multichannel and belong to the class of devices with feedbacks between channels. The presence of feedbacks between channels is stipulated by the Markov property of discrete component describing types of radio source movement. In the quasi-optimal adaptive algorithm, the processing of measurement values coming from sensors of the sensor network is performed by using the sequential calculation procedure. At the same time, this algorithm ensures polygaussian approximation of a posteriori probability density of the estimated vector of parameters of radio source movement. The analysis of quasi-optimal algorithm is carried out by employing the computer-aided statistical simulation using an example of estimating the movement parameters of UAV performing different kinds of maneuvers and sending out radio waves.

FILTRATION OF PARAMETERS OF THE UAV MOVEMENT AT COMPLEX USE OF DATA SENSOR NETWORKS, OBTAINED BASED ON THE TDOA AND RSS METHODS

Background. At the present time the development of technologies for construction of unmanned aerial vehicles (UAVs) are used for the solution of a wide range of tasks, such as: emergency rescue operations, autonomous observation and monitoring of industrial processes and environment (fauna monitoring), etc. On the other hand, their availability and massive use for a wide range of problems has led to the emergence of a new class of threats: application in terrorist purposes, photographing of secret objects, receiving unauthorized access to information in WLAN networks, invasion on the forbidden territory, etc. This leads to the need to develop security systems that solve the problem of detection, positioning and movement parameters of the UAV. Objective. Synthesize algorithm the filtration of parameters of the UAV movement at complex use of data, obtained based on the TDOA and RSS methods. Methods. Synthesis of algorithm the filtration of parameters of the UAV movement at complex use of data, obtained based on the TDOA and RSS methods, it is executed on the basis of the mathematical device of the extended Kalman filter. Efficiency analysis of a developed algorithm is carried out by means of statistical modeling. For descriptive reasons of the algorithm works the test trajectory of the UAV movement has been created. Results. As appears from results of modeling, complex use of data allows reducing RMS errors of the position estimation of the UAV more, than by 3 times, in comparison with independent processing on the basis of the data obtained by the TDOA and RSS methods.. Conclusions. The algorithm filtration of parameters of the UAV movement synthesized on the basis of a mathematical apparatus of the expanded Kalman filter is recurrent and implements a sequential procedure for combining data obtained on the basis of the TDOA and RSS methods. The developed algorithm takes into account the dispersion of power measurement errors, received signals by sensors of the sensor network and determines the estimate of the unknown error of measuring the arrival time signal of the reference sensor.

METHODS FOR RADIO SPECTRUM EVALUATION AND MONITORING

Due to the extensive growth of wireless communications, the usage of radio bands requires a substantial optimized approach and rational treatment. Many new emerged communication scenarios necessitate techniques for optimal spectrum evaluation and monitoring. This paper discusses various such approaches and particularly focuses on spectrum sharing and coexistence presenting several case studies. It offers insights into simulation, modeling and measurement-based methodologies related to spectrum evaluation and utilization, focusing on the effects before and after the digital switchover (DSO) of the TV systems. We investigate the usability of the different propagation models in current wireless systems modeling, including the measurement-based validation of their precision for different scenarios. The article, furthermore, presents laboratory experiments on DVB-T and LTE-800 coexistence. Finally, it discuses a designed example of a nationwide monitoring system for intruder detection, comparing several applied methods and their precision. Key words: radio spectrum; measurement; modeling; LTE; DTV; intruder detection REFERENCES: [1] P. K. Agyapong, et al.: Design considerations for a 5G network architecture, IEEE Communications Magazine, 52, 11, 65–75 (2014). [2] Horizon 2020 Advanced 5G Network Infrastructure for Future Internet PPP – Creating a Smart Network that is Flexible, Robust and Cost Effective,http//ec.europa.eu/di-gital agenda/futurium/en/content/horizon-2020-advanced-5g-network-infrastructure-future-internet-ppp-creating- smart-network, accessed, Oct. 2014. [3] A. Ichkov, V. Atanasovski, L. Gavrilovska: Analysis of Two-Tier LTE Network with Randomized Resource Allocation and Proactive Offloading, Mobile Networks and Applications, 2016, pp. 1–8, DOI: 10.1007/s11036-016-0754-0. [4] ITU World Radiocommunications Conference 2015. http://www.itu.int/en/ITU-R/conferences/wrc/2015/Pages/default.aspx. [5] P. Latkoski,, J. Karamacoski,, L. Gavrilovska,: Availability assessment of TVWS for Wi-Fi-like secondary system: A case study, 7 th International Conference on Cognitive Radio Oriented Wireless Networks – CROWN-COM 2012, Stockholm, Sweden, June 18–20, 2012. [6] Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3000 MHz, International Telecommunications Commission (ITU), Rec.ITU-R P. 1546–3, 2007. [7] P. Rice, A. Longley, K. Norton, A. Barsis: Transmission Loss Predictions for Tropospheric Communication Circuits, Volume I, National Bureau of Standards, Technical Note, vol. 101, 1967. [8] Bernard Pauchon: Digital Switch Over Experiences across Europe, ITU International Symposium – Digital Switchover, Geneva, June 17 th , 2015. [9] Universal Software Radio Peripheral 2 (USRP2). Information available: http://www.ece.umn.edu/users/ravi0022/class/ee4505/ettus_ds_usrp2_v5.pdf. [10] D. Denkovski, V. Atanasovski, L. Gavrilovska: Practical evaluation of LTE-800 and DVB-T coexistence, IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), Ghent, Belgium, June 17–19, 2015. [11] OFCOM Technical Report: Technical analysis of interference from mobile network base stations in the 800 MHz band to digital terrestrial television, June, 2011. [12] A. Grambozov, V. Atanasovski, L. Gavrilovska: Practical evaluation of TDoA, AoA and hybrid methods for geolocation of wireless transmitters, IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), Ghent, Belgium, June 17–19, 2015. [13] http://orca.feit.ukim.edu.mk

Emitter localisation from reception timestamps in asynchronous networks

We address the problem of localising a mobile terminal (“blind” node) in unknown position from a set of “anchor” nodes in known positions. The proposed method does not require any form of node synchronisation nor measurement (or control) of the transmission times, which is difficult or anyway costly to achieve in practice. It relies exclusively on reception timestamps collected by the anchor nodes, according to their local clocks, that overhear packets transmitted by the blind node and by (at least one) other transmitting node(s) in known position, e.g., other anchors. The clock differences between the nodes are not eliminated ex ante through clock synchronisation, as in traditional ToA and TDoA methods. Instead, they are counteracted ex post, during the data processing stage, leveraging the data redundancy that is intrinsic to the multiple reception of the same packet by different (anchor) nodes. We validate the proposed method in different experimental settings, indoor and outdoor, using exclusively low-cost Commercial-Off-The-Shelf WiFi devices, achieving sub-metre accuracy in full line-of-sight conditions and metre-level accuracy in mild non-line-of-sight environment. The proposed method does not require that the blind node participate actively to the localisation procedure and can use “opportunistically” any legacy signal or packet available over-the-air for communication purposes. Considering the very minimal requirement on the system—basically, only that anchors in known positions are able to collect and share reception timestamps—the proposed approach can enable practical adoption of opportunistic and/or cooperative localisation on top of existing radio communication systems.