Real-time positioning method and system based on radio frequency fingerprints

Abstract

The invention provides a real-time positioning system based on radio frequency fingerprints. A positioning tag is adopted to transmit a short data packet initiatively; a reader measures the corresponding signal intensity and sends the signal intensity to a positioning server; and the positioning server takes charge of the data synchronization and estimates the position of the positioning tag. Through adopting the system, the data transmitting quantity of the positioning tag is reduced, the energy consumption of the positioning tag is lowered, the working time of the tag after being charged once is prolonged, also because a mixed Gaussian distribution model, a mechanism of selection of a preset number of readers with the maximum signal intensity based on a common reader collection and a mechanism of adaptive region searching are applied to the positioning server, the positioning accuracy of the system is improved, and the calculation amount is reduced.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and in particular relates to a real-time positioning technology based on radio frequency signal strength. Background technique [0002] In recent years, with the development of wireless communication technology and the widespread deployment of various wireless networks, based on wireless fidelity (Wireless Fidelity, referred to as WiFi) and radio frequency identification (Radio Frequency Identification Devices, referred to as RFID) and other short-range wireless communication technologies Positioning technology has received more and more attention. The main reason is that short-distance wireless positioning technologies such as WiFi and RFID not only do not require line-of-sight, but also do not require additional expensive positioning infrastructure. At present, these short-distance positioning technologies have become a useful supplement to GPS and other satellite positioning, es...

AI Technical Summary

Problems solved by technology

[0005] (1) In the training stage, a single Gaussian distribution model is mostly used to represent the distribution characteristics of the received signal strength in the grid, which cannot accurately reflect the distribution characteristics of the received signal strength in complex scenes

Because radio frequency signals are affected by random factors such as multipath propagation, shadow fading, non-line-of-sight obstruction, transceiver hardware calibration accuracy, personnel activities, and temperature and humidity changes, radio frequency signals have strong time-varying and random characteristics. Does not obey the Gaussian distribution, adopts an approximate Gaussian model, resulting in large positioning errors

[0006] (2) In the positioning stage, most of the existing radio frequency fingerprint positioning methods choose to conduct a global search within the entire positioning area when performing fingerprint matching search, and need to perform matching operations on each grid, and the positioning calculation cost is relatively large. When the area is large and there are many nodes to be positioned, the real-time positioning performance is poor

Since no common reader set is used between different grids (reader sets received at different grid locations are generally different), the likelihood function values ​​of different grids are not comparable

In addition, the reader set may also contain some readers with very far distances and very weak signals. Such readers do not have much reference value for the likelihood calculation of the grid, but will cause errors

[0008] (4) The existing radio frequency fingerprint positioning method does not effectively use historical data or neighbor node information, resulting in the positioning results jumping back and forth, and the robustness is not good

The energy consumption of such a scanning process includes the energy consumption of sending and receiving two communications in all channels and the energy consumption of waiting for the reader to respond in the middle, resulting in high energy consumption for positioning

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