Situation assisted indoor localization using signals of opportunity

Development of an accurate, less-complexity indoor positioning system using Smartphone is the scope of this research. In an indoor environment, a Smartphone can communicate with the signals of opportunity. The signals for experimentation include Wi-Fi, Bluetooth, GSM and optical signals which will almost be available in all the buildings and a Smartphone can communicate with all these signals based on the facilities provided in modern day mobile phones. The problems associated with indoor scenario are the architectural styles of the buildings which obstruct the Line of Sight [LOS] between the Smartphone and the signals of opportunity. In Non-Line of Sight [NLOS] scenario, it is difficult to estimate the position accurately. It is really a challenging task to deal with the indoor environment with walls and corridors because the ranging error in LOS and NLOS conditions is different. To avoid this problem, a communication system is modeled as a frequency selective channel model that uses LOS and NLOS signals in the available frequencies. The signal which has the highest Signal to Noise [SNR] ratio, low Bit Error Rate [BER] and maximum throughput parameters is chosen by the parameter selection algorithm based on statistical analysis, as these three parameters are essential to estimate the location accuracy. The communication system which satisfies these three parameters for the particular indoor environment at a particular frequency is chosen as the site specific path loss model. The indoor environment is completely covered with site specific path loss models with applicable frequencies. Empirical measurements were done for single user and multi user path loss models in first floor of our University Building based on the available frequencies. The experimental results showed that our communication system is applicable to Wi-Fi, Bluetooth, GSM and Optical signals in LOS and NLOS conditions providing site specific indoor positional accuracy.