Position Of Transmitter Research Articles

Performance Analysis of Future Multigigabit Wireless Communication Systems at THz Frequencies With Highly Directive Antennas in Realistic Indoor Environments

In this paper, a simulation environment encompassing realistic propagation conditions and system parameters is employed in order to analyze the performance of future multigigabit indoor communication systems at tetrahertz frequencies. The influence of high-gain antennas on transmission aspects is investigated. Transmitter position for optimal signal coverage is also analyzed. Furthermore, signal coverage maps and achievable data rates are calculated for generic indoor scenarios with and without furniture for a variety of possible propagation conditions.

Analysis and Focusing of Bistatic Airborne SAR Data

Bistatic synthetic aperture radar (SAR) processing requires precise knowledge about geometrical parameters of the flown bistatic constellation, whereas estimation of these parameters is even more important than in the monostatic case. As it is impossible to separate the individual semimonostatic parameters from the bistatic raw data, the searched parameters are derived from the tracks of the moving platforms. For this reason, global positioning system (GPS) and inertial navigation system (INS) position and velocity data of transmitter and receiver are combined in an optimal way by a Kalman filter approach. As a consequence of model-based interpolation, we can easily determine varying parameters like Doppler centroid frequency, azimuth velocity, and the bistatic parameters a2 and a0 referring to the illuminated scene at each time instant. Accurately determined position and velocity of the transmitter and receiver enable a first-order bistatic motion compensation (MC), which is also described in this paper. In verifying our approach, GPS/INS tracks and raw data of a bistatic airborne SAR experiment flown in 2003 were used, where the data were provided by Forschungsgesellschaft fu umlr Angewandte Naturwissenschaften e.V., Wachtberg, Germany. The focusing was done by a scaled inverse Fourier transformation processor for nearly parallel trajectories for transmitter and receiver. This paper focuses on analyzing the trajectories and antenna beams of bistatic missions to obtain accurate processing parameters and MC functions.

State Space Initiation for Blind Mobile Terminal Position Tracking

Blind localization and tracking of mobile terminals in urban scenarios is an important requirement for offering new location-based services, handling emergency cases of nonsubscribed users, public safety, countering IEDs, and so forth. In this context, we propose a track-before-detect scheme taking explicitly advantage of multipath propagation in an urban terrain by using a priori information about the known locations of the main scattering objects such as buildings. This information is made available for localization and tracking by a real-time ray tracing technique based on a 2D geographic database. This allows the prediction of the directional and temporal structure of the received multipath components for an arbitrary transmitter position. We consider a single observing station where the direction and the relative time of arrival of the received multipath components can be estimated by an antenna array. By a likelihood function, which is algorithmically defined for a randomly distributed set of potential transmitter positions, these measurements are compared with those being expected by ray tracing. This likelihood function is the key component of a track-before-detect scheme providing initial state estimates for mobile transmitter tracking using a particle filtering technique.

초음파와 RF를 이용한 자세결정

GPS is widely used for positioning applications and attitude of a vehicle can be found also with multiple antennas. However, extremely weak signal level prevents GPS from indoor operation. DR with accelerometers and gyros and landmark based localization method used for indoor applications increase complexity and cost. In this paper, a simple but very efficient ultrasound based attitude determination system which determines both position and attitude in WSN is given. The range between transmitter and receivers are measured using the arrival time difference between ultrasound and RF signal. The 3 dimensional positions can be found using more than 3 range measurements. Furthermore, if more than 2 transmitters are used, the attitude can be determined using the baseline vectors obtained by differencing transmitter and receiver positions. The prototype system is implemented to evaluate the performance of the proposed method. In addition, an error analysis shows the relation between the attitude error and basel me length, quality of measurement and orientation of a vehicle. The static and dynamic experiments performed by micro mobile robot shows accurate position with less than 1.5cm error and attitude with less than 1 degree error can be obtained continuously with 20cm baseline. It is expected that these results can be adapted without modification to indoor applications such as home cleaning robot and autonomous wheelchair maneuvering.

Guided waves in marine CSEM

Recently, marine controlled source electromagnetics (CSEM) has shown great potential in hydrocarbon exploration, where the goal is to detect thin resistive layers at depth below the seafloor. The experiment comprises a horizontal electric dipole transmitter towed over an array of receivers at the seafloor. The transmitter emits a low-frequency signal (<1 Hz) and measurements of the electric field are made. The depth of the target layer requires transmitter—receiver separations of several kilometres. As a function of separation r, the electromagnetic signal consists of a short-ranging contribution with an exponential decay resulting from the transmission through ocean and sediment (including the reflection at all interfaces) and a long-ranging contribution with a dominant 1/r3 -decay associated with the airwave guided at the air—ocean interface. Of particular interest among the exponentially decaying waves is the wave guided in the resistive target layer with a well-defined long decay length. In a shallow sea, this ‘resistive-layer mode’ is partly masked by the airwave. The topics of this study are the airwave and the resistive-layer mode. For a general 1-D conductivity distribution we derive the simple expression of the leading term of the airwave for arbitrary transmitter and receiver position and define a ‘pure’ complete airwave, which for all separations is close to the asymptotic expansion of the airwave in powers of 1/r. Whereas the treatment of the airwave can be done in terms of Bessel function integrals with real wavenumbers, the resistive-layer mode requires the complex wavenumber plane, where it is defined as the residual at the TM-mode pole with the smallest imaginary part. For sufficiently high integrated resistivity of the layer, we give a simple method to determine the position of this pole. In the complex wavenumber plane, the pure complete airwave is presented by a branch-cut integral. For a typical model, this study concludes with the remarkable result that the superposition of airwave and resistive-layer mode provides an excellent description of the electric field over a wide range of separations.

Novel Heuristic UTD Coefficients for the Characterization of Radio Channels

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents novel heuristic coefficients for the uniform theory of diffraction (UTD), suited to analyze the scattering by lossy conducting wedges in an efficient and reciprocal manner. For its reciprocal properties, the coefficients are appropriate to handle complex scenarios with arbitrary transmitter and receiver positions. The new coefficients take advantage of two previously proposed heuristic coefficients, combining both in a novel approach. The diffraction by arbitrary conducting wedges is investigated and results are compared with those given by accurate Maliuzhinets and method-of-moments analyses. The proposed technique is then applied to characterize the scattering through a typical urban scenario in order to demonstrate its applicability. </para>

Effect of transmitter positions on received power and bandwidth in diffuse indoor optical wireless systems

Diffuse Indoor Optical wireless systems (DIOWS) have potential applications in indoor WLAN. The major problems faced by these systems are their reduced bandwidth and restricted mobility caused by multi-path reflections from the indoor surfaces. These systems also suffer from non-uniform power distribution. Over the last decade several techniques have been suggested to circumvent these problems, most of them requiring complex trans-receiver design. One simple technique that can solve the non-uniformity problem is the use of multiple sources in place of a single source. In this paper we compare the received power levels on the floor computed using the extended ceiling bounce and the modified recursive models. The effect of multiple sources and their positions on the channel bandwidth is also analyzed. We show that the channel bandwidth for a given trans-receiver configuration depends on both the horizontal separation (between the transmitter and the receiver) and their actual positions.

Remote experiment of ultrashort-pulse reflectometry for large helical device plasmas

An ultrashort-pulse reflectometer (USPR) has been applied to the large helical device plasmas in National Institute for Fusion Science for edge density profile measurement. Remote control system using super science information network has been introduced to the USPR system. The remote console at Kyushu University having graphical user interface is prepared to control the instruments of the USPR via the general-purpose interface bus. The operations such as the adjustment of supply voltage fed to amplifiers and the frequency doubler, timing control of the impulse, data acquisition, and monitoring can be performed from the remote site. The position of transmitter and receiver antennas can also be controlled remotely in order to observe the cutoff layer depending on various plasma conditions. The directly recorded signal by a sampling scope is analyzed and reconstructed by means of the signal record analysis method.

Assessing the cortical thickness of long bone shafts in children, using two-dimensional ultrasonic diffraction tomography

Echography is one of the first-line techniques used in clinical practice to diagnose osteoarticular diseases in children. However, this technique involves the use of standard equipment, which is not adapted to the morphology or the acoustical properties of children’s bones. In this study, we developed an ultrasonic tomography method for measuring the cortical thickness of children’s long bones. Ultrasonic tomography gives cross-sectional images showing the spatial distribution of some of the physical components of an object, based on scattered ultrasound measurements. These measurements are carried out using variably dense sets of transmitter and receiver positions and various the wave frequencies. We solved this inverse scattering problem using a Born approximation, which yields an attractively simple linear relation between the object function and the scattered field, particularly in the far field. Experiments with a 2D-ring antenna show the applicability of the method and its various improvements to bone thickness imaging. (E-mail: lasaygues@lma.cnrs-mrs.fr)

Sounding rocket flight experiment for demonstrating “Furoshiki Satellite” for large phased array antenna

University of Tokyo and Kobe University are planning a sounding rocket experiment of large membrane “Furoshiki Satellite” extension and large phased array RF transmission. The paper will describe the concept of “Furoshiki Satellite,” its application to solar power satellite, and the scenario of micro-gravity experiment using a small sounding rocket. University of Tokyo has been proposing the idea of “Furoshiki Satellite,” a large membrane or a net structure, say 1 km × 1 km in size, extended by satellites which hold its corners. The attitude and the shape of the membrane or net structure is controlled by these corner satellites. As one application of Furoshiki Satellite, a large solar power satellite can be configured by several solar cells and RF transmitters placed on several parts of the large net structure. It is difficult to control the position and attitude of the RF transmitters precisely, but using the “retro-directive” method, the tolerance of such position and attitude disturbance will be relaxed by large. This is one of promising systems’ concept of the future large solar power satellite or large antenna, because quite a large area can be obtained without any hard structure, and the weight will not depend very much on the size. To demonstrate the feasibility of the extension of large net structure and phased array performance, micro-gravity experiment is planned using a sounding rocket of JAXA/ISAS, Japan.

Application of Beamforming in Wireless Location Estimation

A simple technique to estimate the position of a given mobile source inside a building is based on the received signal strength. For this methodology to have a reasonable accuracy, radio visibility of the mobile by at least three access points is required. To reduce the number of the required access points and therefore simplify the underlying coverage design problem, we propose a novel scheme that takes into account the distribution of RF energy around the receiver. In other words, we assume that the receiver is equipped with a circular array antenna with beamforming capability. In this way, the spatial spectrum of the received power can be measured by electronically rotating the main lobe around the 360-degree field of view. This spatial spectrum can be used by a single receiver as a means for estimating the position of the mobile transmitter. In this paper, we investigate the feasibility of this methodology, and show the improvement achieved in the positioning accuracy.

Radio network planning of DVB‐H/UMTS hybrid mobile communication networks

AbstractThe benefit of hybrid mobile communication networks combining point‐to‐point and point‐to‐multipoint systems should be an optimised transfer of data for both providers and customers. In this paper, the focus is on joint radio network planning of hybrid mobile communication networks consisting of unicast (UMTS) and broadcast (DVB‐H) delivery systems. Optimised network planning is a non‐trivial task even for a single network. Hence, planning and optimisation of hybrid networks implicate great challenges. For these issues, realistic traffic estimations are required. Therefore, a scenario has been developed based on the public reference scenario of Berlin from the IST‐MOMENTUM project. A method for designing a DVB‐H network architecture including transmitter position and cell size is introduced. Furthermore, the necessary transmitting power is estimated. The evaluation of the benefit of a hybrid network is introduced and shown in an example. Copyright © 2006 AEIT.

Large membrane “Furoshiki Satellite” applied to phased array antenna and its sounding rocket experiment

University of Tokyo and Kobe University are planning a sounding rocket experiment of large membrane “Furoshiki Satellite” extension and large phased array RF transmission. The paper will describe the concept of “Furoshiki Satellite,” its application to phased array antenna, and the scenario of micro gravity experiment using a small sounding rocket. University of Tokyo has been proposing the idea of “Furoshiki Satellite,” a large membrane or a net structure, say 1 km × 1 km in size, extended by satellites which hold its corners. The attitude and the shape of the membrane or net structure is controlled by these corner satellites. As one application of Furoshiki Satellite, a large phased array antenna can be configured by several RF transmitters placed on several parts of the large net structure. It is difficult to control the position and attitude of the RF transmitters precisely, but using the “retro-directive” method, the tolerance of such position and attitude disturbance will be relaxed by large. This is one of promising systems’ concept of the future large solar power satellite or large antenna, because quite a large area can be obtained without any hard structure, and the weight will not depend very much on the size [S. Motohashi, T. Nagamura, Large scaled membrane structure Furoshiki Satellite—its concept and orbital/attitude dynamics, in: Proceedings of 20th International Symposium on Space Technology and Science (ISTS), 1996, p. 96-n-14]. To demonstrate the feasibility of the extension of large net structure and phased array performance, micro-gravity experiment is planned using a sounding rocket of ISAS/JAXA, Japan.

Examination of Optical Power Distribution in Indoor Optical Networks

In this study, the power distribution problem in the indoor wireless local area network has been studied. Optical power distribution produced by multiple light sources in an office or a shop was examined. It has been worked on the effects affecting the power distribution such as patterns of the light source and number of transmitter. As a function of the room size, number of transmitters and transmitter positions were calculated. To be able to do this, a computer program was prepared and the simulation was performed. Simulation approach was used to achieve the uniformity of the power distribution. As a result, it has been understood that the best power distribution is achieved by placing optical sources as the square like grids on the ceiling of the room.

Automatic Mesh Generation for Mobile Network Dimensioning Using Evolutionary Approach

We focus on the dimensioning process of cellular networks that addresses the evaluation of equipment global costs to cover a city. To deal with frequency assignment, that constitutes the most critical resource in mobile systems, the network is usually modeled as a pattern of regular hexagonal cells. Each cell represents the area covered by the signal of a transmitter or base station (BS). Our work emphasizes on the design of irregular hexagonal cells in an adaptive way. Hexagons transform themselves and adapt their shapes according to a traffic density map and to geometrical constraints. This process, called adaptive meshing (AM), may be seen as a solution to minimize the required number of BS to cover a region and to propose a basis for transmitter positioning. The solution we present to the mesh generation problem for mobile network dimensioning is based on the use of an evolutionary algorithm. This algorithm, called hybrid island evolutionary strategy (HIES), performs distributed computation. It allows the user to tackle problem instances with large traffic density map requiring several hundreds of cells. HIES combines local search fast computation on individuals, incorporated into a global island-like strategy. Experiments are done on one real case representing the mobile traffic load of the second French city of Lyon and on several other traffic maps from urban fictive data sets.

A novel technique for reducing the imaging domain in microwave imaging of two dimensional circularly symmetric scatterers

A novel technique for reducing the imaging domain in microwave imaging of 2D circularly symmetric scatterers is presented. The degree of symmetry vector of the measured scattered field is employed for the purpose of localizing the scatterer. The degree of symmetry for a transmitter position is computed as a function of the difference between the first half and the spatially reflected second half of the measured scattered-field vector. The symmetry plots exhibit unique features of the direction and distance to the scatterer from the centre of the imtances from the centre, permittivities, and radii are studied, which enables the localization of the cylinder in the imaging domain I, thereby allowing the reduction of the imaging domain to I r . Some typical symmetry plots are considered in Figure 3, where the symmetry plots have been generated from noisy measurement data with an SNR of 30 dB. The symmetry positions are 19 and 44. The distances between the asymmetry positions through 19 and through 44 along the measurement circle are more different in Figure 3(b) than in Figure 3(a). The peak values at the asymmetry positions are much smaller in Figure 3(a) than in Figure 3(b), indicating that the circularly symmetric scatterer is very close to the origin in the first example and farther away from the origin and closer to the transmitter position 44 in the second case. In the case of Figure 3(c), the degree of symmetry values for all the transmitter positions are very small, thus indicating that the object centre and the centre of the imaging domain coincide. The reduced imaging domains in the three cases are chosen accordingly, as indicated in Figure 4. The Newton-Kantorovich procedure has been employed for the imaging of the approximately located scatterer. Figure 5(a) shows the actual profile of a 2D circularly symmetric dielectric scatterer. Its degree of symmetry values for the different transmitter positions are plotted in Figure 5(b). Figure 5(c) shows the reconstructed image after the sixth iteration of the Newton-Kantorovich procedure when the entire imaging region is employed. The reconstructed image when the reduced imaging region is employed, as shown in Figure 5(d). The result obtained using the proposed technique is seen to be much better. There is also a considerable reduction in computation time, as compared to the case where the entire imaging domain is employed.

電磁式管路位置測量システムの開発

It is useful to employ jacking method for construction of lifelines. We have developed an electromagnetic positioning system of underground pipes at the depth between 10 and 15 m. This system consists of a receiver coil on the ground surface and a transmitter coil in the subsurface pipe. The used frequency is approximately 1 kHz and the magnetic moment of the transmitter coil is around 50 ATm2.The prototype system estimates a transmitter position as a cross point of detected magnetic lines at some receiver points. The estimation error of 0.5∼2.0 m resulted from the field tests is higher than the requested one. The improved system synchronizing a receiver clock with a transmitter and limiting a search area small over the transmitter was developed. This system has two measuring modes of rough and detail search. In the first mode, the maximum voltage induced in the vertical receiver coil indicates the transmitter position roughly. In another mode, an exact position is found as a point indicating zero voltage in the horizontal receiver coil. An exact point is shown visibly and easily in the graphic screen on the receiver.Results obtained in some jacking pipe sites proved that the improved system achieved the tolerance below 5 cm horizontally.

A Novel Technique for Localizing the Scatterer in Inverse Profiling of Two Dimensional Circularly Symmetric Dielectric Scatterers Using Degree of Symmetry and Neural Networks

A novel technique for localizing the scatterer in microwave imaging of two-dimensional circularly symmetric dielectric scatterers using degree of symmetry and neural networks is presented. The degree of symmetry for a transmitter position is computed as a function of the difference between the first half and the spatially reflected second half of the measured scattered field vector. A Probabilistic Neural Network (PNN) classifier is trained with the degree of symmetry vectors for the different object configurations. It classifies the degree of symmetry vector of the unknown circularly symmetric scatterer presented to it into one of the classes that indicate the radius and location of the centre of the scatterer. Thus the scatterer is localized in the imaging domain. This not only reduces the degrees of freedom in the inversion for the unknown object, thereby aiding the global convergence of the solution, but also results in a reduction in computation time. The technique has been tested on synthetic data and the results are promising.

Electromagnetic cave-to-surface mapping system

This paper presents the principle, design, construction, and methodology for an electromagnetic (EM) system to be used in the detection/location and mapping of underground cavities using surface measurements. The EM instrument consists of a loop-loop transmitter/receiver system with the transmitter placed inside the cavity. The transmitter's position and depth are determined by analyzing the shape and distribution of the transmitted field on the surface. From the perspective of a cylindrical coordinate system, the vertical component of the through rock transmitted magnetic field peaks at the point where the transmitter and receiver are vertically collinear. On the other hand, the horizontal component reaches a minimum at this point. Based on these observations, a procedure is presented and tested that efficiently locates the position as well as the depth of the transmitter. A physical model for the system was developed and compared to the results of calibration experiments, with very good agreement. The model allows the study of different responses for EM waves/fields propagating through a homogenous Earth of different electrical characteristics and therefore enables several type-curves to be generated that aid in the development of an optimal system.

Using a Geographic Information System to Assess the Accuracy of Radio-Triangulation Techniques for Fish Telemetry

We evaluated the accuracy of several triangulation methods that produce quantified rather than inferred transmitter position data on the movements of brown trout Salmo trutta in an urbanized stream. Other telemetry studies have reported accuracies of 0.5-5 m based on visual observation of fish or detection of hidden transmitters from within streams. With our geographic information system (GIS) method, coordinate locations for each transmitter position were recorded without entering the water. A global positioning system (GPS) was used to record coordinate locations on the stream bank and compass bearings with signals of hidden transmitters in the stream. Signal locations were then triangulated to estimate the coordinates of transmitter locations. Location coordinates were placed onto a GIS coverage, and accuracy was determined by comparing the actual positions of hidden transmitters with the estimated positions. Three different triangulation methods produced slightly different accuracies. Our GIS method is less biased and supported by data and could provide a standard method for triangulation. Moreover, the GIS-based radio-triangulation approach enables tracking in the field without disturbing a tagged fish in its habitat or otherwise altering a fish's behavior due to human intervention.