Bluetooth, Floor-Plan, and Microelectromechanical Systems-Assisted Wide-Area Audio Indoor Localization System: Apply to Smartphones

During the past decade, there has been an increasing interest in the audio-based indoor localization approach, which has benefited from the high precision, high privacy, and high security of the passive time difference of arrival (TDoA) positioning. However, the limited bandwidth, and complexity in real-time ID encoding and decoding under an actual reverberate environment make it difficult to achieve wide-area (>1500m2) localization in off-the-shelf smartphones. Plenty of previous work applied to a single region localization only with a small range. In this paper, a hybrid acoustic signal transmission architecture based on frequency division multiple access (FDMA), time division multiple access (TDMA), and space division multiple access (SDMA) is perfected to cover the acoustic signal to a wider range. With the prior information of the Bluetooth and floor-plan, smartphones estimate which cell themselves are located in accurately. We further propose the strategies of data bias integrity monitoring, dynamic variance adjustment based on the micro-electro-mechanical systems (MEMS) sensors, and the floor-plan restraint to enhance the particle filter and make the smartphones tracking smarter and more robust. The proposed prototype system can provide decimeter-level localization accuracy and stable 1Hz update rate in several typical wide indoor environments with less infrastructure.