Accurate indoor global absolute localization systems are of great interest in different public indoor locations like metro stations, shopping malls and others. The present invention provides a method to deliver accurate indoor global absolute localization information using only audio signals, inaudible to the users, broadcasted by common loudspeakers in an area of interest. This approach differs from the indoor localization solution as it makes uses off-the-shelf hardware, typically pre-existing devices either in the infrastructure or on the mobile device’s side, and provides high accuracy and reliability.



The presented system allows accurate access to indoor global absolute position of common mobile devices (like a smartphone, tablet, etc) using their microphone to capture audio signals, broadcasted in an area of interest. The periodic emission of audio signals for localization is provided by the public address sound system already present in an infrastructure. Besides the proprietary encoding and decoding algorithms for position estimation,  this invention also consists on the method for encoding and covering these signals in audio already transmitted by the local sound infrastructure, making it barely audible for the user, but also on the usage of a mobile device as receiver of this audio information. 


Compared to currently available technologies, the benefits of this technology are multiple. First, it enables high accuracy global position estimation, in the range of centimeters, for multiple users, adequate for indoor events and/or public places. Also, because it uses off-the-shelf inexpensive components like common loudspeakers, usually pre-existing, the costs of such solution are typically lower than its counterparts. Additionally, because the users are not required to emit any signal, security and privacy is insured, and the associated energy consumption of the user’s mobile devices is reduced.

Potential comercial use/applications: 

The present invention provides centimeter level position estimation in multiple public or private places and indoor events. The potential of application of such technology is significant as it may be applied to every situation where indoor localization may be of interest for context-aware applications. Some possibilities include, but are not limited to, hospitals, shopping malls, transportation hubs and administrative buildings, museums, cultural spots and places of touristic interest, educational institutions, conference and exhibition centers and sport facilities. Additionally, this can also be included in accessibility applications for the visually impaired.


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