SpotFi

Abstract

This paper presents the design and implementation of SpotFi, an accurate indoor localization system that can be deployed on commodity WiFi infrastructure. SpotFi only uses information that is already exposed by WiFi chips and does not require any hardware or firmware changes, yet achieves the same accuracy as state-of-the-art localization systems. SpotFi makes two key technical contributions. First, SpotFi incorporates super-resolution algorithms that can accurately compute the angle of arrival (AoA) of multipath components even when the access point (AP) has only three antennas. Second, it incorporates novel filtering and estimation techniques to identify AoA of direct path between the localization target and AP by assigning values for each path depending on how likely the particular path is the direct path. Our experiments in a multipath rich indoor environment show that SpotFi achieves a median accuracy of 40 cm and is robust to indoor hindrances such as obstacles and multipath.

State-of-the-Art Mobile Intelligence: Enabling Robots to Move Like Humans by Estimating Mobility with Artificial Intelligence

“…Assuming an antenna array of M antennas is equally spaced by a distance of d and a signal arriving at the antenna array through L propagation paths, the signal travels an additional distance of d × sinθ by the signal to reach the second antenna of the array [48].…”

Assessment of Receiver Signal Strength Sensing for Location Estimation Based on Fisher Information

“…This can be represented as an additional dimension in the RM based on the Ricean K-factor. Detection of LOS further allows for a possible bearing angle observation between the MWD and AP [33]. However, the processing of CSI is more complex and often ill posed.…”

TrackCC: A Practical Wireless Indoor Localization System Based on Less-Expensive Chips

“…Bluetooth ILS [2] suffers from similar limitations. WiFi ILS can achieve a centimeter level localization precision [3,4]. However, it is required to equip high-power and relatively expensive WiFi chips with continuous AC power supplies into mobile devices and deploy a number of wireless access points.…”

“…The major contributions of our work are summarized as follows:

Based on a commercial low-cost low-power system-on-chip, nRF24LE1, the proposed system can achieve decimeter-level accuracy for indoor localization and outperform a classical power level based ILS, LANDMARC, and a recently proposed ILS, SAIL. In addition, in the aspect of hardware cost, for a medium or large localization area, unlike SpotFi [3] that needed to deploy multiple access points (APs) with continuous power supplies, and LANDMARC, including its variants VIRE [12] and SAIL[11], which needed to deploy very expensive RFID readers to receive the signal of tags with relatively long distances, the proposed system just needs to deploy the corresponding number of cheap wireless nodes according to actual site area.

This paper introduces the Markov theory to remove the fluctuation in power levels, which has not been addressed in the literature.We propose a priority-based pattern matching technique to find the most similar power level vector with fingerprint based localization methods. We found a noteworthy phenomenon that, even if two power level vectors are similar in Euclidean distance, their corresponding nodes may still be located at two far-away points in the constructed radio map.…”

“…In addition, in the aspect of hardware cost, for a medium or large localization area, unlike SpotFi [3] that needed to deploy multiple access points (APs) with continuous power supplies, and LANDMARC, including its variants VIRE [12] and SAIL[11], which needed to deploy very expensive RFID readers to receive the signal of tags with relatively long distances, the proposed system just needs to deploy the corresponding number of cheap wireless nodes according to actual site area.…”