Alexander Goetz

A novel technique for mobile phone localization for search and rescue applications

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. Search and Rescue with modern localization techniques consequently attracts attention from scientific and industrial sides. This paper introduces one part of the I-LOV project, endorsed by the Federal Ministry of Education and Research Germany. Here partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. Future developments in the area of mobile phone detection by field intensity measurements will be addressed in this paper.

GSM mobile phone localization using time difference of arrival and angle of arrival estimation

The localization methods time difference of arrival (TDOA) and angle of arrival (AOA) are investigated in their capability of high-resolution detection of GSM signals. Because GSM is of narrowband nature, a bandwidth expansion technique that significantly increases the resolution of TDOA is introduced. The algorithms maximum likelihood estimator (for TDOA), root multiple signal classification and estimation of signal parameters via rotational invariance techniques (for AOA) are proposed as a reference for each method. Simulations conducted with noisy signals and multipath propagation demonstrate the potential of TDOA for GSM localization, especially for search and rescue applications. AOA on the other hand is very sensitive to multipath, and is therefore only recommended for open space scenarios.

A power saving jamming system for E-GSM900 and DCS1800 cellular phone networks for search and rescue applications

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. Search and Rescue with modern localization techniques consequently attracts attention from scientific and industrial sides. This paper introduces one part of the I-LOV project, endorsed by the German Federal Ministry of Education and Research. In this project partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. To locate a person by his or her mobile phone requires to take over the phone by an own Base Transceiver Station (BTS). Jamming all other networks is one option to achieve that. This paper will introduce a new Field Programmable Gate Array (FPGA) based jamming system which consumes little power and disturbs only small parts of the GSM spectrum but reliably cuts all connections between mobile stations (MS) and existing BTS.

A time difference of arrival system architecture for GSM mobile phone localization in search and rescue scenarios

In this work, a novel architecture of a time difference of arrival based localization system for GSM mobile phones is proposed. The system is well-suited for search and rescue scenarios and comprises receiving stations for GSM signals, a dedicated GSM base station and a radio frequency jamming system for GSM and UMTS signals. The system may be operated in the E-GSM 900 band providing high penetration of the covering debris material and a sufficient overall bandwidth for the time difference of arrival measurements. In this case, the best attainable accuracy of localization is shown to be in the scale of 5m. The components of the system are described in more detail and possible implementations are proposed. The system may also be applied for the localization of UMTS mobile phones making use of the integrated GSM functionality. The proposed system represents a novel approach for time difference of arrival based localization of mobile phones in search and rescue scenarios.

A smart jamming system for UMTS/WCDMA cellular phone networks for search and rescue applications

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. This paper introduces one part of the I-LOV project, endorsed by the German Federal Ministry of Education and Research. In this project partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. To locate a person by his or her mobile phone requires to take over the phone by an own Base Transceiver Station (BTS). Jamming all other networks is one option to achieve that. This paper will introduce a new Field Programmable Gate Array (FPGA) based jamming system which disturbs only the absolute necessary parts of the WCDMA spectrum but reliably cuts all connections between mobile stations (MS) and existing BTS. The whole system including the signal generator and the front end will be discussed. Also measurement results will be shown.

An ultra wideband positioning system enhanced by a short multipath mitigation technique

In this paper an approach for high precision local positioning radar using an ultra wideband technique is presented. The concept is based on the standard FMCW (frequency modulated continuous wave) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. In this way, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D and 3D localization. A prototype was built which operates at a center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a standard deviation down to 6 mm. Additionally, we studied the effects of short multipath propagation and present simulation results for an applicable mitigation technique.

A power sensor unit for the localization of GSM mobile phones for search and rescue applications

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. Recent examples are Haiti 2010 and Fukushima 2011. Search and Rescue with modern localization techniques consequently attracts attention from scientific and industrial sides. This paper introduces a field strength measurement unit, which is part of the I-LOV project1. In this project partners from relief organizations, universities, and industry investigate enhancements in disaster handling and victim rescue. One possible option is to take advantage of the fact that most people own a mobile phone today and take it with them the whole day. To locate a person by his or her mobile phone requires to find the maximum of its radiated field strength. This paper will show a new power sensor unit for GSM signals. The complete design flow from requirements considerations to measurement results will be demonstrated. A dynamic range of 107 dB is only one of the remarkable outcomes.

Short Multipath Mitigation Technique Using Feedforward Neural Networks

In this paper a novel approach for mitigation of short multi-path distortions is presented. The technique is applicable to FMCW-based distance measurement systems assuming distinctly separated targets. The effects of spectral distortion caused by short multipath propagation in conjunction with Fourier-based frequency analysis methods are mitigated. For this purpose the distorted spectrum is first analyzed and specific characteristics are calculated. A Feedforward Neural Network processes these characteristics and provides a correction frequency relative to the erroneously shifted maximum in order to estimate the true line-of-sight frequency. A comprehensive analysis was performed by means of a two tone test. Applicability to real world environments was investigated by means of a multi tone test using an IEEE 802.15.4a channel model.