Katsuyuki Haneda

An application of SAGE algorithm for UWB propagation channel estimation

In this paper, a new ultra wideband (UWB) channel estimation algorithm, UWB-SAGE (space alternating generalized expectation maximization) is proposed. In the algorithm, a novel UWB signal model which is an extension of the conventional wideband signal model is employed in order to estimate the UWB channel with SAGE algorithm. The algorithm divides the measured data into individual ray paths and estimates the directions of arrival, propagation time, and the variation of the amplitude and phase during the propagation for each signal. The measurement campaign in indoor environment was conducted and it was shown that the algorithm could correctly extract the inherent propagation phenomena of the channel. The estimation result can be very useful for the design and analysis of UWB communication system, especially for the evaluation of waveform distortion and multipath effect.

Cluster Properties Investigated From a Series of Ultrawideband Double Directional Propagation Measurements in Home Environments

Results from double directional ultrawideband (UWB) channel sounding in a wooden house are described. The double directional channel sounder estimates directional information at both ends of the link, so that we can separate antenna directivity from the channel sounding results. We investigated the dominant propagation mechanisms by introducing cluster analyses. The detected propagation paths from the channel sounding were first classified into clusters in the angular-delay domain, and then properties of the clusters such as standard deviation of path positions, dynamic range of path power, and power distribution of clusters were derived. From the results, we discussed the similarities and differences between the measurement environment and the physical propagation phenomena. Finally, different types of scattering losses of the propagation paths were derived and modeled. The results from sounding and analysis contribute in the development of UWB propagation models and can be used in UWB propagation simulations

High-resolution estimation of NLOS indoor MIMO channel with network analyzer based system

This report presents a MIMO sounding system dedicated to short range wireless communication. The system can easily be integrated with a vector network analyzer (VNA) and other commercial equipments. The advantage of our proposed system is the achievement of completely automatic measurement, while retaining accuracy. Using the system, a double directional measurement campaign in indoor NLOS environment was performed, where the channel was estimated in a deterministic way with the ISI-SAGE algorithm. In the use of ISI-SAGE algorithm, we propose to estimate polarization characteristics for identical path. One of the realizations of the optimum search and initialization with successive interference cancellation type procedure, which is suitable for a large number of sampling, available case is shown as well. The result of the measurement campaign shows the effectiveness of our proposals.

Experimental evaluation of a SAGE algorithm for ultra wideband channel sounding in an anechoic chamber

The paper presents the results of experiments in an anechoic chamber that assessed the reliability of a UWB channel sounding system based on a deterministic approach with a SAGE algorithm. The system could resolve and detect waves separated by 10/spl deg/ in the angle domain, which was near the resolution limit. In the delay domain, waves separated by 0.67 ns could be resolved where the relation between the bandwidth of the subband and spectrum estimation was discovered. The behavior of the algorithm for the detection of incident waves which are within the resolution limit was examined. The spherical incident wave model was applied for estimating the parameters of incident waves. This model could drastically reduce the number of spurious paths compared to the plane wave model.

Applicability of UWB Double Directional Propagation Modeling for Evaluating UWB Transmission Performance

This paper investigates the applicability of deterministic ultra wideband (UWB) propagation modeling for evaluating UWB system performances. The modeling explores the wave propagation characteristics on both transmitting and receiving antenna sides, which is known as the double directional modeling. In evaluating the applicability, bit error probability (BEP) performances were derived using two kinds of channel impulse responses: 1) raw data which were measured by channel sounding campaign and 2) reconstructed data from the propagation modeling results. In the BEP simulation, the direct sequence UWB system was considered. Comparison of the BEP performances from two kinds of channels revealed that the concept of the double directional modeling was capable of evaluating BEP performances accurately. However, it was also found that the limitation of our double directional modeling approach based on the model-based ray path extraction method resulted in the limited capability in modeling the total received power. As a consequence, fading statistics of the reconstructed channels were different from the measured data, ending up with less accuracy to predict BEP performances depending on the data rate. Finally, possible solutions to improve the double directional propagation modeling were suggested.

Polarimetric measurement of nonspecular wave scattering from building surface roughness

The paper presents polarimetric measurements of nonspecular scattering from rough building surfaces. Both V-V and V-H polarizations were estimated independently. The superresolution method was applied as an approach to handle the signal parameters of individual incoming waves scattered from rough building surfaces. In order to comprehend the details of microscopic scattering mechanisms, signal parameters are incorporated into the geometrical ray tracing.

High-Precision Time-of-Arrival Estimation for UWB Localizers in Indoor Multipath Channels

The global positioning system (GPS) has found application in many different fields, in areas where there is a good line-of-sight (LoS) to GPS satellites, this technique provides a good estimate of the location of user terminal (UT). However, in indoor and dense urban environments, localization has always been a more challenging problem for several reasons. Typically the GPS signal is not strong enough to penetrate through most materials. As soon as an object obscures the GPS satellite from the UT’s view, the signal is corrupted. This constrains the usefulness of GPS to open environments, and limits its performance in forests or in dense urban environments, as retaining a lock on the GPS signals becomes more difficult. GPS typically becomes completely useless inside buildings. However there is an increasing need for accurate localization in cluttered environments, in addition to open spaces. In commercial applications for example, the tracking of inventory in warehouses or cargo ships is an emerging need. In military applications the problem of blue force tracking, i.e., knowing where friendly forces are, is of vital importance. This is not a problem in open environments where systems can rely on GPS, but in dense urban or indoor environment, no satisfactory solution exists. Navigation in GPS-denied environment is also a pressing military need. For example untethered robots operating in enclosed environments such as urban canyons or inside buildings need accurate positioning to safely navigate. Indoor localization is of great importance for the applications that a person or a vehicle enter a building and accurately tracking its position over time is needed and the position estimate should have a precision of under one meter, i.e. on the order of some of the building feature dimensions, such as hallway width.

Investigation of Ultra-Wideband Propagation Channel based on a Cluster Scheme

In this paper, an Ultra-Wideband (UWB) double-directional channel sounding measurement and spatio-temporal analysis of UWB propagation based on the clusterization approach were reported. After separating the propagation paths and diffuse components both on the transmitter (Tx) antenna and receiver (Rx) antenna positions, the propagation paths both on Tx and Rx positions were observed for clusters separately, while coupling the clusters between Tx and Rx position based on similar time of arrivals, and ray tracing by utilizing high temporal and spatial resolution, respectively. The relation between direction of departure and direction of arrival will then be investigated. For cluster properties, parameters of model characteristics are discussed and compared to other earlier works.

Evaluation of Signal Quality Improvement With Rake Reception Using an Ultrawideband Indoor Area Propagation Measurement

Achievable improvement of signal quality using rake reception was evaluated for ultrawideband impulse-radio and spread-spectrum systems. The evaluation was based on extensive area propagation measurement in a line-of-sight office environment. Influence of large- and small-scale propagation behavior on improvement of receiving signal-to-noise ratio (SNR) was analyzed. The analyses revealed that having eight fingers could achieve sufficient improvement of receiving SNR under practical conditions. It was also demonstrated that eight-finger rake reception could extend service coverage and reduce outage probability.

Superresolution measurement of non-specular wave scattering from building surface roughness

This paper presents a superresolution measurement of non-specular scattering from 3D building surface roughness. The superresolution method was applied as an approach to handle signal parameters (DOA, TOA) of the individual incoming waves reflected from building surface roughness. In order to comprehend in detail the microscopic mechanisms of scattering, signal parameters are to be incorporated into the geometrical ray tracing. The results show that the multiple paths can be detected from many scatterers, such as ground, window glass, window frame, bricks surface, as well as directly from the transmitter. Most of the scattered waves arrive closely from specular directions. The calculation of glass and bricks reflection coefficient can be performed based on data measurement.