Accurate Positioning Using Long Range Active RFID Technology to Assist Visually Impaired People Saleh Alghamdi, Ron van Schyndel and Ibrahim Khalil School of Computer Science and IT RMIT University Melbourne, VIC 3000, Australia. s3299407@student.rmit.edu.au,ron.vanschyndel@rmit.edu.au,ibrahimk@cs.rmit.edu.au Abstract The aim of this paper is to describe a new positioning technique to assist the blind and people with low vision to indicate their location and reach their destinations in both indoor and outdoor environments. The proposed technique is based on a combination of power attenuation and a signal strength indicator (SSI) using active Radio-frequency identification (RFID) technology. The system uses a mobile reader with a power attenuation feature. SSI is used as a distance estimator for a short range and in combination with one of eight receiver attenuation level settings for a wider range of up to 70 meters. A Global Positioning System (GPS) works efficiently in a similar environment but is only accurate to around ten to twenty meters and does not work efficiently in indoor environments. This research produced an identification localization system which identifies various locations such as offices, laboratories, theaters and so on to assist users reach their destination of interest. It was then implemented in an indoor environment as a real empirical case study to identify laboratories based on a combined technique with a successful identification rate of around 98%. The reader has eight attenuation settings, and the geographic range of each level using various tags was calculated. Then, to evaluate reliability, 108 experiments were conducted using three tags with distances from 1 metre to 25 metres, using power settings 1 to 6. A successful detection rate of 93.5% was achieved, as well as a false positive rate of 1%. Following this, the system was implemented in a park to evaluate its ability to indicate the position of the reader among a grid of tags in an open area. A satisfactory result was achieved. Keywords: Active RFID, Accurate Positioning, Power Attenuation, Signal Strength Indicator, Blind Assistance 1. Introduction For blind and low vision people, determining their current location is a significant challenge. Over the years, various re- searchers have discussed navigation issues using RFID tech- nology in order to assist visually impaired people. This work can be classified into three categories. The first group of re- searchers used passive RFID technology for positioning in in- door environments. An advantage of passive RFID technology is that it does not require a power supply because it depends on the power of the probe signal itself for data transformation purpose. Furthermore, passive RFID is relatively inexpensive. The second group of researchers used active RFID technology in both indoor and outdoor environments, but almost all of their proposed systems did not use active RFID technology by it- self, rather they combined it with other technologies such as GPS. The third group of researchers used active RFID based on distributing transmitters (readers) in the ceiling for triangu- lation purpose then uses the Received Signal Strength Indicator (RSSI) technique to estimate the position of the tag which is carried by a user. However, they have few obvious disadvan- tages: • The disadvantage of passive RFID approach is that it re- quires a very short distance to communicate between the reader and the tag. • The disadvantage of the second approach is that when GPS is unavailable, such as in between skyscrapers or inside buildings, their system is disabled or may provide inac- curate positioning information because GPS accuracy is around ten to twenty meters. • The disadvantage of the third approach is more costly strategy because it based on distributing readers rather than distributing tags. In this research which is development of our previous re- search Alghamdi and van Schyndel (2012), we extend the indoor-only method described there to include an outdoor envi- ronment. The improved system is able to inform blind and low vision people of their current position whether indoors or out- doors and provide them with useful information to guide them to their destination using active RFID technology. The novelty of the system is based on a new technique which is a combina- tion of a choice of eight attenuation levels and signal strength, enabling users to determine their position using a portable mo- bile device. Therefore, the proposed system works efficiently Preprint submitted to Journal of Network and Computer Applications November 23, 2012