CN111413671B - LiFi technology-based multi-PD positioning method and system - Google Patents
LiFi technology-based multi-PD positioning method and system Download PDFInfo
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- CN111413671B CN111413671B CN202010348171.9A CN202010348171A CN111413671B CN 111413671 B CN111413671 B CN 111413671B CN 202010348171 A CN202010348171 A CN 202010348171A CN 111413671 B CN111413671 B CN 111413671B
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- 230000005540 biological transmission Effects 0.000 claims description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/16—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using electromagnetic waves other than radio waves
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/114—Indoor or close-range type systems
- H04B10/116—Visible light communication
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- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
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- Computer Networks & Wireless Communication (AREA)
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Abstract
The invention relates to a multi-PD positioning method and a system based on LiFi technology, wherein the invention provides a light reflection path according to a laser pulse ranging principle, a ranging module is introduced, each PD of a LiFi AP receiving end carries out coherent detection according to known sending signals and received signals, so as to obtain accurate position information of each PD and a terminal, then an accurate spatial position relation between the terminal and the AP is obtained according to a space triangle calculation method, and the AP obtains final accurate position information of the terminal according to the position information of the AP and the accurate spatial position relation between the terminal and the AP. The multi-PD positioning method and system based on LiFi technology have the advantages of simplicity, economy and good instantaneity, fully utilize the interval between the downlink signal and the uplink signal, have no influence on the LiFi protocol, ensure high-speed communication and realize the positioning function.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a multi-PD positioning method and system based on LiFi technology.
Background
There is an increasing trend to implement location-based services and applications, such as indoor navigation or opportunistic marketing, which requires more accurate Indoor Positioning Systems (IPS), and currently common indoor positioning technologies include wireless fidelity (WiFi), bluetooth, radio Frequency (RF), ultra Wideband (UWB), infrared and Visible Light Communications (VLC), etc.
The VLC has very high Positioning Accuracy (PA) and energy efficiency, is low in positioning cost, has the capability of resisting the interference of the traditional radio frequency signals, and becomes a research hot spot of indoor positioning technology in recent years. The positioning of visible light wireless communication (LiFi) mainly comprises two modes of direct positioning and two-step positioning: direct positioning techniques are often very complex, but do not require prior parameter estimation to obtain an optimal solution; the two-step positioning method performs data extraction in the first stage and estimates the position in the second stage, thereby giving a suboptimal result. The existing LiFi positioning technology mainly comprises five methods of proximity, fingerprint, triangulation, visual analysis and a hybrid algorithm.
Proximity, fingerprint and triangulation methods use a Photodiode (PD) as the receiver, requiring a multiplexing process; the visual analysis technology takes a camera as a receiver without multiplexing; the hybrid algorithm uses a photodiode or camera as the receiver, multiplexing being optional.
However, the communication mode of the camera as a receiver cannot be compatible with the LiFi protocol, so that the speed of an image sensor of the camera is slow, and high-speed data transmission cannot be realized; the communication method using the photodiode as the receiver requires accurate time synchronization between the receiving end and the transmitting end, and has high time precision requirement.
Disclosure of Invention
The invention aims to provide a multi-PD positioning method and a system based on LiFi technology, which realize high-precision positioning and quick positioning according to an accurate positioning method of a light reflection loop and can be applied to a plurality of PD receivers.
The invention solves the problems by adopting the following technical scheme: a multi-PD positioning method based on LiFi technology comprises the following steps:
(1) The LiFi terminal sends a positioning request to the LiFi AP receiving end, and simultaneously sends a terminal modulation-demodulation time interval delta t and a terminal ID to the AP.
(2) The AP allocates the appointed downlink measurement time slot SL according to the reporting terminal ID i 。
(3) The AP measures and transmits the known S in the appointed measurement time slot t Signal, S t The signals are sent to the AP ranging module while being sent to the terminal receiver PD through the visible light LED.
(4) The terminal opens the switch K to demodulate S in the appointed measurement time slot r The signal is sent to the modulator, and is sent to the AP receiving end through the infrared LED, and the infrared LED signal is amplified by the amplifier and then is sent to the AP ranging module.
(5) Each PD of the AP corresponds to a ranging module according to the known S t The signal and the received amplified infrared LED signal are subjected to coherent operation and the time delta t of terminal modulation and demodulation is subtracted, so that the time difference between emission and reflection is obtainedΔtrx, and calculating the corresponding distance d by Δtrx PD-X ，d PD-X = ((Δtrx- Δt)/2) speed of light, the time difference Δtrx may also be used to synchronize the AP clock T AP And clock T of terminal TE ，T TE =T AP -[(Δtrx-Δt)/2]。
(6) AP end-to-multiple distances d PD-X And carrying out space trigonometric operation to obtain the space position, namely the distance and azimuth relation, of the terminal.
Preferably, the coherent operation in step (5) is a deconvolution calculation.
Preferably, step (4) is said S r The signal transmission time is determined by the ranging procedure.
The invention further aims to provide a multi-PD positioning system based on LiFi technology, which comprises a LiFi AP end and a LiFi terminal, wherein the LiFi AP end and the LiFi terminal both comprise a transmitting device and a receiving device, the common LED visible light of a transmitting signal of the LiFi AP end transmitting device is connected with the receiving end of the LiFi terminal receiving device, and the infrared LED signal of the transmitting end of the LiFi terminal transmitting device is connected with the receiving end of the LiFi AP end receiving device.
Preferably, the LiFi AP end transmitting device includes a first coding memory, an output end of the first coding memory is connected to an input end of a first analog-to-digital converter, an output end of the first analog-to-digital converter is connected to an input end of a first signal modulator and an input end of a ranging module, an output end of the first signal modulator is connected to an input end of a first LED driving controller, and an output end of the first LED driving controller is connected to an LED lamp.
Preferably, the LiFi AP end receiving device includes a first PD receiver, an output end of the first PD receiver is connected to an input end of a first amplifier, an output end of the first amplifier is connected to an input end of a first signal demodulator and an input end of a ranging module, and an output end of the first signal demodulator is connected to a first encoding processor through a first digital-to-analog converter.
Preferably, the number of the LiFi AP receiving devices is at least 4, each receiving device is independent, and each receiving device is provided with a corresponding first PD receiver, a first amplifier, a first signal demodulator, a ranging module, a first digital-to-analog converter and a first coding processor.
Preferably, the lif terminal sending device comprises a second coding memory, the output end of the second coding memory is connected with the input end of a second analog-to-digital converter, the output end of the second analog-to-digital converter is connected with the input end of a second signal modulator, the output end of the second signal modulator is connected with the input end of a second LED driving controller, and the output end of the second LED driving controller is connected with an infrared LED lamp.
Preferably, the LiFi terminal receiving device includes a second PD receiver, where the second PD receiver is connected to an input end of a second signal demodulator through a second amplifier, the input end of the second signal demodulator is connected to an input end of a second digital-to-analog converter and an input end of a second signal modulator, and an output end of the second digital-to-analog converter is connected to a second encoding processor.
Compared with the prior art, the invention has the advantages that:
(1) According to the laser pulse ranging principle, the invention provides the light reflection path, and the uplink light is subjected to coherent detection through multiple DPs to obtain accurate distance information, wherein the coherent detection method is to deconvolute or perform coherent wave crest detection through the known pulse signals and the received known pulse signals, so that the LiFi-based multi-PD high-precision positioning method is simple, economical and good in real-time performance.
(2) The optical pulse detection method utilizes the existing mature detection algorithm through the optimized structure, reduces the complexity of the system and improves the efficiency.
(3) The method based on the LiFi protocol fully utilizes the time division multiplexing characteristic of the LiFi protocol, fully utilizes the interval between the downlink signal and the uplink signal, has no influence on the LiFi protocol, can realize high-speed data transmission, and simultaneously realizes the positioning function.
(4) The positioning system and the positioning method can accurately synchronize the AP clock and the clock of the terminal.
Drawings
Fig. 1 is a schematic diagram of a multi-PD positioning system based on LiFi technology in an embodiment of the present invention.
Fig. 2 is an enlarged view of the LiFi AP end in the multi-PD positioning system based on LiFi technology of fig. 1.
Fig. 3 is an enlarged view of a LiFi terminal in the multi-PD positioning system based on LiFi technology of fig. 1.
Fig. 4 is a flowchart of a multi-PD positioning method based on LiFi technology in an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
As shown in fig. 4, a flowchart of a multi-PD positioning method based on LiFi technology in the present embodiment.
A multi-PD positioning method based on LiFi technology comprises the following steps:
(1) The LiFi terminal sends a positioning request to the LiFi AP receiving end, and simultaneously sends a terminal modulation-demodulation time interval delta t and a terminal ID to the AP.
(2) The AP allocates the appointed downlink measurement time slot SL according to the reporting terminal ID i 。
(3) The AP measures and transmits the known S in the appointed measurement time slot t Signal, S t The signals are sent to the AP ranging module while being sent to the terminal receiver PD through the visible light LED.
(4) The terminal opens the switch K to demodulate S in the appointed measurement time slot r The signal is sent to the modulator, and is sent to the AP receiving end through the infrared LED, and the infrared LED signal is amplified by the amplifier and then is sent to the AP ranging module.
(5) Each PD of the AP corresponds to a ranging module according to the known S t The signal and the received amplified infrared LED signal are subjected to coherent operation and the time delta t of terminal modulation and demodulation is subtracted to obtain the time difference delta trx between emission and reflection, and the corresponding distance d is calculated through delta trx PD-X ，d PD-X = ((Δtrx- Δt)/2) speed of light, the time difference Δtrx may also be used to synchronize the AP clock T AP And clock T of terminal TE ，T TE =T AP -[(Δtrx-Δt)/2]。
(6) AP end-to-multiple distances d PD-X And carrying out space trigonometric operation to obtain the space position, namely the distance and azimuth relation, of the terminal.
As shown in fig. 1, in the embodiment, a multi-PD positioning system based on the LiFi technology is illustrated in schematic diagram, fig. 2 is an enlarged view of the LiFi AP end in the multi-PD positioning system based on the LiFi technology, and fig. 3 is an enlarged view of the LiFi terminal in the multi-PD positioning system based on the LiFi technology.
The multi-PD positioning system based on the LiFi technology comprises a LiFi AP end and a LiFi terminal, wherein the LiFi AP end and the LiFi terminal both comprise a transmitting device and a receiving device, the common LED visible light of a transmitting signal of the LiFi AP end transmitting device is connected with the receiving end of the LiFi terminal receiving device, and the infrared LED signal of the transmitting end of the LiFi terminal transmitting device is connected with the receiving end of the LiFi AP end receiving device.
The LiFi AP end sending device comprises a first coding memory, the output end of the first coding memory is connected with the input end of a first analog-to-digital converter, the output end of the first analog-to-digital converter is respectively connected with the input end of a first signal modulator and the input end of a ranging module (comprising a ranging module A, a ranging module B, a ranging module C and a ranging module D), the output end of the first signal modulator is connected with the input end of a first LED driving controller, and the output end of the first LED driving controller is connected with an LED lamp.
The LiFi AP receiving devices are 4, each receiving device is independent and is provided with a corresponding first PD receiver, a first amplifier, a first signal demodulator, a ranging module, a first digital-to-analog converter and a first coding processor. The method comprises the following steps: the output end of the first PD receiver A is connected with the input end of the first amplifier A, the output end of the first amplifier A is respectively connected with the input end of the first signal demodulator A and the input end of the ranging module A, and the output end of the first signal demodulator A is connected with the first coding processor A through the first digital-analog converter A; the output end of the first PD receiver B is connected with the input end of the first amplifier B, the output end of the first amplifier B is respectively connected with the input end B of the first signal demodulator A and the input end of the ranging module B, and the output end of the first signal demodulator B is connected with the first coding processor B through the first digital-analog converter B; the output end of the first PD receiver C is connected with the input end of the first amplifier C, the output end of the first amplifier C is respectively connected with the input end of the first signal demodulator C and the input end of the ranging module C, and the output end of the first signal demodulator C is connected with the first coding processor C through the first digital-analog converter C; and the output end of the first PD receiver D is connected with the input end of the first amplifier D, the output end of the first amplifier D is respectively connected with the input end of the first signal demodulator D and the input end of the ranging module D, and the output end of the first signal demodulator D is connected with the first coding processor D through the first digital-analog converter D.
The LiFi terminal sending device comprises a second coding memory, the output end of the second coding memory is connected with the input end of a second analog-to-digital converter, the output end of the second analog-to-digital converter is connected with the input end of a second signal modulator, the output end of the second signal modulator is connected with the input end of a second LED driving controller, and the output end of the second LED driving controller is connected with an infrared LED lamp.
The LiFi terminal receiving device comprises a second PD receiver, the second PD receiver is connected with the input end of a second signal demodulator through a second amplifier, the input end of the second signal demodulator is respectively connected with the input end of a second digital-to-analog converter and the input end of a second signal modulator, and the output end of the second digital-to-analog converter is connected with a second coding processor.
In addition to the above embodiments, the present invention also includes other embodiments, and all technical solutions that are formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.
Claims (10)
1. A multi-PD positioning method based on LiFi technology is characterized in that: the method comprises the following steps:
(1) The LiFi terminal sends a positioning request to a LiFi AP receiving end, and simultaneously sends a terminal modulation-demodulation time interval delta t and a terminal ID to the AP;
(2) The AP allocates the appointed downlink measurement time slot SL according to the reporting terminal ID i ；
(3) The AP transmits the known S in the designated measurement slot t Signal, S t The signal is sent to the terminal receiver PD through the visible light LED and is simultaneously sent to the AP ranging module;
(4) The terminal opens the switch K to demodulate S in the appointed measurement time slot r The signal is sent to the modulator, and is sent to the AP receiving end through the infrared LED, and the infrared LED signal is amplified by the amplifier and then is sent to the AP ranging module;
(5) Each receiver PD at the AP end corresponds to a ranging module according to the known S t The signal and the received amplified infrared LED signal are subjected to coherent operation and the time delta t of terminal modulation and demodulation is subtracted to obtain the time difference delta trx between transmission and reflection, and the corresponding distance d is calculated through delta trx PD-X ，d PD-X = ((Δtrx- Δt)/2) speed of light, wherein the AP end includes at least four receivers PD;
(6) AP end-to-multiple distances d PD-X And carrying out space trigonometric operation to obtain the space position, namely the distance and azimuth relation, of the terminal.
2. The LiFi technology-based multi-PD positioning method of claim 1, wherein: the coherent operation in step (5) is deconvolution calculation.
3. The LiFi technology-based multi-PD positioning method of claim 1, wherein: step (4) the step S r The signal transmission time is determined by the ranging procedure.
4. The LiFi technology-based multi-PD positioning method of claim 1, wherein: the time difference Deltatrx of step (5) is also used to synchronize the AP clock T AP And clock T of terminal TE ，T TE =T AP -[(Δtrx-Δt)/2]。
5. A multi-PD positioning system based on LiFi technology, employing the positioning method according to any one of claims 1 to 4, characterized in that: the LiFi AP terminal comprises a LiFi AP terminal and a LiFi terminal, wherein the LiFi AP terminal and the LiFi terminal both comprise a transmitting device and a receiving device, the common LED visible light of the transmitting signal of the LiFi AP terminal transmitting device is connected with the receiving end of the LiFi terminal receiving device, and the infrared LED signal of the transmitting end of the LiFi terminal transmitting device is connected with the receiving end of the LiFi AP terminal receiving device.
6. The LiFi-based multi-PD location system of claim 5, wherein: the LiFi AP end sending device comprises a first coding memory, the output end of the first coding memory is connected with the input end of a first analog-to-digital converter, the output end of the first analog-to-digital converter is respectively connected with the input end of a first signal modulator and the input end of a ranging module, the output end of the first signal modulator is connected with the input end of a first LED driving controller, and the output end of the first LED driving controller is connected with an LED lamp.
7. The LiFi-based multi-PD location system of claim 5, wherein: the LiFi AP end receiving device comprises a first PD receiver, the output end of the first PD receiver is connected with the input end of a first amplifier, the output end of the first amplifier is respectively connected with the input end of a first signal demodulator and the input end of a ranging module, and the output end of the first signal demodulator is connected with a first coding processor through a first digital-to-analog converter.
8. The lif-based multi-PD positioning system of claim 5 or 7, wherein: at least 4 LiFi AP receiving devices are arranged, each receiving device is independent and is provided with a corresponding first PD receiver, a first amplifier, a first signal demodulator, a ranging module, a first digital-to-analog converter and a first coding processor.
9. The LiFi-based multi-PD location system of claim 5, wherein: the LiFi terminal sending device comprises a second coding memory, the output end of the second coding memory is connected with the input end of a second analog-to-digital converter, the output end of the second analog-to-digital converter is connected with the input end of a second signal modulator, the output end of the second signal modulator is connected with the input end of a second LED driving controller, and the output end of the second LED driving controller is connected with an infrared LED lamp.
10. The LiFi-based multi-PD location system of claim 5, wherein: the LiFi terminal receiving device comprises a second PD receiver, the second PD receiver is connected with the input end of a second signal demodulator through a second amplifier, the input end of the second signal demodulator is respectively connected with the input end of a second digital-to-analog converter and the input end of a second signal modulator, and the output end of the second digital-to-analog converter is connected with a second coding processor.
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| WO2016210432A1 (en) * | 2015-06-26 | 2016-12-29 | Apollo Robotic Systems Incorporated | Robotic apparatus, systems, and related methods |
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