High-precision indoor positioning method for WiFi signal direct line-of-sight propagation path mining

A propagation path and indoor positioning technology, applied in wireless communications, services based on specific environments, electrical components, etc., can solve the problems of signal attenuation, small application range, polarization change, etc., to eliminate the influence and reduce the computational complexity. Effect

Inactive Publication Date: 2021-12-28
ZHEJIANG UNIV CITY COLLEGE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1) The existing positioning methods based on the Fresnel zone theoretical model usually require that there should be no obstacles between the transmitting and receiving antennas, and the strong constraints lead to a small scope of application;
[0005] 2) The existing indoor positioning methods use the channel state information of the direct line-of-sight propagation path and the indirect non-line-of-sight propagation path, but the multipath effect of the indirect non-line-of-sight propagation path will cause delay synchronization, signal attenuation, polarization Changes, unstable links, etc. make the positioning accuracy of the existing technology drop sharply after a period of use

Method used

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  • High-precision indoor positioning method for WiFi signal direct line-of-sight propagation path mining
  • High-precision indoor positioning method for WiFi signal direct line-of-sight propagation path mining
  • High-precision indoor positioning method for WiFi signal direct line-of-sight propagation path mining

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Experimental program
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Effect test

Embodiment 1

[0051] Embodiment 1 of the present application provides a method such as figure 1 The shown high-precision indoor positioning system based on the signal propagation path of commercial WiFi equipment includes: a WiFi access point 5 for sending radio frequency signals, and a positioning target device 3 (for example, a smart phone) for receiving radio frequency signals , tablet, mobile computer or smart bracelet with WiFi function, etc.), the positioning server 6 for running the positioning method. In an indoor environment, due to obstructions (such as wall 1), WiFi wireless signals form multipath propagation paths (indirect propagation path 2 and direct propagation path 4) through reflection and diffraction, and different objects cause different interference to the propagation path. The characteristics of signals generated by people located in different locations are also different.

[0052] Using a high-precision indoor positioning system based on the signal propagation path o...

Embodiment 2

[0054] On the basis of Embodiment 1, Embodiment 2 of the present application provides a method such as figure 2 The shown high-precision indoor positioning method based on the signal propagation path of commercial WiFi equipment includes the following steps:

[0055] S1. The application of OFDM technology in IEEE 802.11a / n protocol enables the collection of channel state information and signal strength of WiFi signals through the signal propagation path of commercial WiFi devices, and provides subcarrier phase and amplitude information to describe wireless signals Change information from the transmitter to the receiver;

[0056] S2. In an indoor environment, the WiFi signal of the positioning target may be reflected by multiple obstacles (for example, walls and furniture, etc.) before finally reaching the WiFi access point, and the angle of arrival of the propagation path from the positioning target to the WiFi access point is estimated ;

[0057] S202. Since it is difficul...

Embodiment 3

[0063] On the basis of embodiment one and embodiment two, such as image 3 As shown, step S2 is specifically:

[0064] S202. Under the IEEE802.11 protocol, the channel state information collected by the antennas of each commercial WiFi device is 30 subcarriers, and all the channel state information collected by the three antennas is expressed as a 3×30 channel state information matrix CSI:

[0065]

[0066] In the above formula, let csi i,j is the number of row i and column j of the channel state information matrix CSI, then csi i,j Indicates the channel state information of the jth subcarrier on the ith antenna;

[0067] Since the WiFi wireless signal propagation path is greater than the number of antennas of the WiFi access point, the multi-signal classification technology is not applicable; therefore, the orthogonal frequency division multiplexing technology of the WiFi technology is used to expand the 3 antennas of the commercial WiFi equipment to 90 virtual antennas ...

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Abstract

The invention relates to a high-precision indoor positioning method for WiFi signal direct line-of-sight propagation path mining. The method comprises the following steps: collecting channel state information and signal strength of WiFi signals through commercial WiFi equipment; estimating an arrival angle of a propagation path from the positioning target to the WiFi access point; identifying a direct propagation path between a positioning target and a WiFi access point by using embedded representation, and weighting and designing a positioning loss function. The beneficial effects of the method are that the method employs the WiFi devices which serve wireless network communication and are widely deployed to serve indoor positioning at the same time, and eliminates the impact on the positioning precision from a wireless signal multipath effect and noise interference in an indoor complex environment. The method comprises the following steps: capturing channel state information of commercial WiFi in an indoor environment, and decomposing arrival angles and flight time of different multipath components of the target signal arriving at a plurality of WiFi access devices by using the channel state information; therefore, centimeter-level high-precision indoor positioning with zero deployment cost is realized.

Description

technical field [0001] The invention relates to the technical field of positioning using radio wave reflection or re-radiation, and in particular to a high-precision indoor positioning method for digging direct line-of-sight propagation paths of WiFi signals. Background technique [0002] Nowadays, with the continuous development of wireless communication technology and the increasing popularity of mobile smart terminals, location-based services have become an important part of the current IT industry. market expectation. Today, the satellite positioning system represented by GPS has covered the global outdoor environment around the clock, profoundly changing people's production and lifestyle. The progress of the times has inspired people's desire to obtain accurate locations anytime, anywhere in the indoor environment. According to the data provided by Nokia, 87% to 90% of human activities are in the indoor environment, so indoor location information is very important for...

Claims

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Application Information

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IPC IPC(8): H04W4/33H04W64/00
CPCH04W4/33H04W64/006
Inventor 陈垣毅
Owner ZHEJIANG UNIV CITY COLLEGE
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