WallSense: Device-Free Indoor Localization Using Wall-Mounted UHF RFID Tags

Area of Science:

• Computer Science
• Electrical Engineering
• Robotics

Background:

• Device-free indoor localization is crucial for various applications.
• Existing methods often require active user participation or dedicated infrastructure.
• Accurate and low-overhead localization solutions are needed.

Purpose of the Study:

• To develop a device-free indoor localization system using Radio-Frequency Identification (RFID).
• To achieve high localization accuracy without requiring users to carry any devices.
• To minimize deployment overhead for practical implementation.

Main Methods:

• The WallSense system utilizes two orthogonal RFID tag arrays installed in adjoining walls.
• It employs Received Signal Strength Indicator (RSSI) and phase information from RFID readers.
• Particle Swarm Optimization (PSO) with a weighted fitness function is used for localization, combining data from both tag arrays.

Main Results:

• WallSense achieves a median localization error of 0.24 meters for human targets.
• The system effectively differentiates backscattered signals between adjacent tag pairs to extract location-relevant information.
• The method successfully eliminates most undesirable environmental factors affecting localization accuracy.

Conclusions:

• WallSense provides an accurate and device-free indoor localization solution.
• The system demonstrates low deployment overhead and requires no active user participation.
• RFID technology, combined with advanced signal processing and optimization, offers a promising approach for ubiquitous indoor positioning.