Localization for visually impaired people in dynamically changing environments\nwith unexpected hazards and obstacles is a current need. Many techniques\nhave been discussed in the literature with respect to location-based\nservices and techniques used for the positioning of devices. Time difference of\narrival (TDOA), time of arrival (TOA) and received signal strength (RSS)\nhave been widely used for the positioning but narrow band signals such as\nBluetooth cannot efficiently utilize TDOA or TOA. Received signal strength\nindicator (RSSI) to measure RSS, has been found to be more reliable. RSSI\nmeasurement estimations depend heavily on the environmental interference.\nRSSI measurement estimations of Bluetooth systems can be improved either\nby improving the existing methodologies used to implement them or by using\nfusion techniques that employ Kalman filters to combine more than one RSSI\nmethod to improve the results significantly. This paper focuses on improving\nthe existing methodology of measuring RSSI by proposing a new method using\ntrilateration for localization of Bluetooth devices for visually impaired\npeople. To validate the new method, class 2 Bluetooth devices (Blue Giga\nWT-12) were used with an evaluation board. The software required was developed\nin National Instruments LabView. The PCB was designed and manufactured\nas well. Experiments were then conducted, and surface plots of\nBluetooth modules were obtained to show the signal interference and other\nenvironmental effects. Lastly, the results were discussed, and relevant conclusions\nwere drawn.
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