Zoubir Irahhauten

An overview of ultra wide band indoor channel measurements and modeling

In this paper, an overview of reported measurements and modeling of the ultra wide band (UWB) indoor wireless channel is presented. An introduction to UWB technology and UWB channels is provided. Different UWB channel sounding techniques are discussed and approaches for the modeling of the UWB channel are reviewed. The available indoor UWB channel measurement results are consulted and accordingly, the major UWB channel parameters are presented and compared to those of narrowband systems. The novelty of this work is the gathering of different UWB channel parameters, analysis, and comparison. Added with the influence of UWB antenna in channel-modeling as well as the frequency-dependency of the channel parameters, leading to a conclusion on the UWB radio channel modeling.

Analysis of a UWB Indoor Positioning System Based on Received Signal Strength

This paper explores the possibility to design an indoor ultra wideband (UWB) ranging and positioning system using the received signal strength (RSS). Due to the extremely large bandwidths, the effects of small scale fading are reduced to the level where the knowledge of the path loss model (PLM) can be employed for accurate and reliable distance estimation. This approach enables trilateration based position estimation while significantly reducing the synchronization effort. A limited number of measurements is necessary in order to calibrate the PLM parameters but no extensive database of measurements is required, such as in fingerprinting methods. Based on simulated UWB channels, the effects of uncertainties in the PLM parameters on the estimated distance are characterized. Data from a UWB measurement campaign in indoor line-of-sight (LOS) scenarios are used to verify the performance of such a system.

UWB Channel Measurements and Results for Office and Industrial Environments

This paper presents the results of ultra wide band (UWB) channel measurements carried out at the campus of Delft University of Technology. The measurements were conducted in an indoor office and industrial environment using a time domain setup which allows measurements from 3.1 to 10.6 GHz. Results on large scale path-loss exponent, shadowing, small scale fading and rms delay spread (RDS) for indoor office and industrial area propagation are presented

UWB channel measurements and results for wireless personal area networks applications

This paper presents the results of ultra wide band (UWB) channel measurements for wireless personal area networks (WPAN). A time domain measurement setup has been developed covering the frequency band from 3.1 GHz to 10.6 GHz. Relevant scenarios for WPAN applications have been proposed and measurements have been conducted in an office at very short distances including both LOS and NLOS cases. Additional NLOS measurements with a human body obstructing the direct path have also been performed to determine the effects of the body on the UWB-WPAN channel characteristics. In addition to this, the near field effect between transmit and receive antenna has been examined and channel parameters such as root-mean-square (RMS) delay spread, Ricean K-factor and path-loss exponent are obtained. These results can be used for analysis and design of UWB systems for WPAN applications

Investigation of UWB Ranging in Dense Indoor Multipath Environments

In this paper, ranging based on UWB signals is investigated for indoor dense multipath environments. To this end, a large set of time domain measurements covering the 3.1-10.6 GHz frequency band is carried out. Different approaches to detect the time of arrival of the first path are evaluated. Ranging results based on time estimation are compared to those based on signal strength. Additionally, the effect of the bandwidth on the range estimates is analyzed. Generally, the results show that high ranging accuracy can be achieved for both LOS and NLOS propagation when UWB is used. Analysis of the data points out that additional delay introduced by propagation through walls is the main source of range error in NLOS indoor environments

Integration of a Pulse Generator on Chip Into a Compact Ultrawideband Antenna

For impulse radio ultrawideband communications an ldquoantenna plus generatorrdquo system is co-designed and an on chip generator is integrated into the antenna. This approach does away with the need for intermediate transmission lines conventionally placed between an RF device/generator and an antenna and therefore eliminates the need for a balun, prevents excitation of the common-mode currents and allows the device to be mounted directly on the antenna. The antenna and generator are designed taking into account both impedance matching and the generators influence on the antennas radiation properties. The suggested approach is verified experimentally at a scaled up version of the antenna.

Suppression of noise and narrowband interference in UWB indoor channel measurements

In this paper, the impact of the noise due to undersampling of noncoherent narrowband interference in time domain UWB channel measurements is investigated. Different measurements were carried out within the building for LOS and NLOS situations. The obtained results show that energy of external narrowband interference (especially at frequencies below 3.1 GHz) is spread over the whole measured bandwidth (1-12 GHz) as a quasi-white noise. This spreading is caused by the stroboscopic sampling receiver used in the measurement setup. The level of this additional noise is relatively high and its suppression is required for long-distance measurements. Suppression of the narrowband interference by an analogue bandpass filter directly after the receive antenna substantially decreases the noise floor and results in a large improvement of the signal-to-noise ratio.

A joint ToA/DoA technique for 2D/3D UWB localization in indoor multipath environment

In this paper, a 2D/3D UWB localization technique based on joint ToA/DoA in indoor dense multipath environment is proposed. In this method, direction of arrival (DoA) is estimated from time of arrival (ToA). The joint usage of ToA and DoA results in an accurate localization of the mobile node (MN). Unlike conventional methods, the proposed localization technique needs only one access point (AP) with an array structure. This consequently eases the synchronization requirement of the proposed localization scheme when compared to the classical ToA-based technique requiring at least 3 synchronized APs. To verify the proposed method real time UWB measurements in dense indoor multipath environment covering 2-6 GHz band were carried out. The results show that accurate 2D/3D localization can be achieved using the proposed scheme. Furthermore, the accuracy performance of the proposed technique is compared to the classical ToA localization technique using at least 3 APs. The results in terms of average range error show that the ToA method slightly outperforms the proposed scheme for the LOS. However, for the NLOS the proposed scheme always provides a better position estimation (i.e. less average range error).

2D UWB localization in indoor multipath environment using a joint ToA/DoA technique

A 2D UWB localization technique based on joint ToA/DoA in indoor dense multipath environment is proposed. In this method, direction of arrival (DoA) is estimated from time of arrival (ToA). The joint usage of ToA and DoA results in an accurate localization of the mobile node (MN). Unlike conventional methods, the proposed localization technique needs only one access point (AP) with an array structure. This consequently eases the synchronization requirement of the proposed localization scheme when compared to the classical ToA-based technique requiring 3 of more synchronized APs. To verify the proposed method real time UWB measurements in dense indoor multipath environment covering 2-6 GHz band were carried out. The results show that accurate 2D localization can be achieved using the proposed scheme. Furthermore, the accuracy performance of the proposed technique is compared to the classical ToA localization technique using more than 3 APs. The results, in terms of average range error, show that the ToA method slightly outperforms the proposed scheme for the LOS. However, for the NLOS the proposed scheme always provides a better position estimation (i.e. less average range error). For instance, the proposed technique provides an average range error of less than 2.3 cm for LOS and 12.3 cm for NLOS situations. The angular error is less than 0.5° and 1.48° for LOS and NLOS scenarios, respectively.

Ultra-wideband indoor propagation channel: Measurements, analysis and modeling

In this paper, the results of ultra wide band (UWB) measurements carried out in indoor environments are presented and a statistical propagation model for the UWB channel covering the frequency band from 3.1 to 10.6 GHz is proposed. The measurements have been performed in the time domain by exciting the channel with very short pulses of 50 ps width. Both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation with a maximum distance of 10 m are considered. Inspection of measured data after processing shows that the multipath components of the UWB channel tend to arrive in clusters. Therefore, the Saleh-Valenzeula (S-V) model has been adopted as starting point for our modelling analysis. Important channel parameter statistics of the model are extracted from the measured data. The obtained results show some discrepancies with respect to the IEEE channel model. The results presented here illustrate that the conventional single Poisson process is not sufficient to model the cluster and ray arrival times. Therefore, a Gamma distribution is proposed to model the cluster inter-arrival times and a mixture of two Poisson processes to model the ray intra-arrival times. It is found that the amplitude fading statistics can be modelled by the log-normal distribution with a standard deviation decreasing linearly with the excess delay. Other parameters like cluster and ray power decay constants are determined to complete the statistical UWB channel model.