Search results for: TDOA/FDOA

Authors: M. H. Chan

Abstract:

This paper describes an application of a dual satellite geolocation (DSG) system on identifying and locating the unknown source of uplink sweeping interference. The geolocation system integrates the method of joint time difference of arrival (TDOA) and frequency difference of arrival (FDOA) with ephemeris correction technique which successfully demonstrated high accuracy in interference source location. The factors affecting the location error were also discussed.

Keywords: Dual satellite geolocation system, DGS, geolocation, TDOA/FDOA, and sweeping interference

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Authors: Peerapong Uthansakul, Monthippa Uthansakul

Abstract:

WLAN Positioning has been presented by many approaches in literatures using the characteristics of Received Signal Strength (RSS), Time of Arrival (TOA) or Time Difference of Arrival (TDOA), Angle of Arrival (AOA) and cell ID. Among these, RSS approach is the simplest method to implement because there is no need of modification on both access points and client devices whereas its accuracy is terrible due to physical environments. For TOA or TDOA approach, the accuracy is quite acceptable but most researches have to modify either software or hardware on existing WLAN infrastructure. The scales of modifications are made on only access card up to the changes in protocol of WLAN. Hence, it is an unattractive approach to use TOA or TDOA for positioning system. In this paper, the new concept of merging both RSS and TOA positioning techniques is proposed. In addition, the method to achieve TOA characteristic for positioning WLAN user without any extra modification necessarily appended in the existing system is presented. The measurement results confirm that the proposed technique using both RSS and TOA characteristics provides better accuracy than using only either RSS or TOA approach.

Keywords: Received signal strength, Time of arrival, Positioning system, WLAN, Measurement.

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Authors: Muhammad R. Ahmed, Xu Huang, Dharmendra Sharma

Abstract:

Despite extensive study on wireless sensor network security, defending internal attacks and finding abnormal behaviour of the sensor are still difficult and unsolved task. The conventional cryptographic technique does not give the robust security or detection process to save the network from internal attacker that cause by abnormal behavior. The insider attacker or abnormally behaved sensor identificationand location detection framework using false massage detection and Time difference of Arrival (TDoA) is presented in this paper. It has been shown that the new framework can efficiently identify and detect the insider attacker location so that the attacker can be reprogrammed or subside from the network to save from internal attack.

Keywords: Insider Attaker identification, Abnormal Behaviour, Location detection, Time difference of Arrival (TDoA), Wireless sensor network

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Authors: Muhammad Irfan Aziz, Thomas Owens, Uzair Khaleeq uz Zaman

Abstract:

The instantaneous and spatial localization for visually impaired people in dynamically changing environments with unexpected hazards and obstacles, is the most demanding and challenging issue faced by the navigation systems today. Since Bluetooth cannot utilize techniques like Time Difference of Arrival (TDOA) and Time of Arrival (TOA), it uses received signal strength indicator (RSSI) to measure Receive Signal Strength (RSS). The measurements using RSSI can be improved significantly by improving the existing methodologies related to RSSI. Therefore, the current paper focuses on proposing an improved method using trilateration for localization of Bluetooth devices for visually impaired people. To validate the method, class 2 Bluetooth devices were used along with the development of a software. Experiments were then conducted to obtain surface plots that showed the signal interferences and other environmental effects. Finally, the results obtained show the surface plots for all Bluetooth modules used along with the strong and weak points depicted as per the color codes in red, yellow and blue. It was concluded that the suggested improved method of measuring RSS using trilateration helped to not only measure signal strength affectively but also highlighted how the signal strength can be influenced by atmospheric conditions such as noise, reflections, etc.

Keywords: Bluetooth, indoor/outdoor localization, received signal strength indicator, visually impaired.

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