CN114615619B - Indoor positioning method based on signal reflection points - Google Patents

Indoor positioning method based on signal reflection points Download PDF

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CN114615619B
CN114615619B CN202210177544.XA CN202210177544A CN114615619B CN 114615619 B CN114615619 B CN 114615619B CN 202210177544 A CN202210177544 A CN 202210177544A CN 114615619 B CN114615619 B CN 114615619B
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signal
receiver
reflection point
excitation source
signals
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CN114615619A (en
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陈凌宇
张少敏
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Xiamen University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/023—Services making use of location information using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7073—Synchronisation aspects
    • H04B1/7075—Synchronisation aspects with code phase acquisition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/021—Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/33—Services specially adapted for particular environments, situations or purposes for indoor environments, e.g. buildings
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention relates to an indoor positioning method based on signal reflection points, which is characterized in that signals are transmitted through an excitation source, the transmitted signals are received by the signal reflection points, the signal reflection points receive signals of the excitation source and the signal reflection points through spread spectrum processing, the signals of the excitation source and the signal reflection points are finally received by a receiver, the distance difference between the signal reflection points can be obtained through processing the received signals, and a TDOA algorithm is adopted for positioning, so that a target position can be finally obtained. The invention utilizes the characteristics of simple structure, lower cost and easy deployment of the signal reflection points, and can realize a large amount of deployment in an indoor positioning scheme.

Description

Indoor positioning method based on signal reflection points
Technical Field
The invention relates to the technical field of indoor positioning, in particular to an indoor positioning method based on signal reflection points.
Background
With the rapid development of society and the modern construction of cities, more and more large-scale buildings are in the life of people. The demands for outdoor positioning in daily life of people have been basically satisfied by the maturity of Global Navigation Satellite Systems (GNSS), such as Global Positioning System (GPS) and beidou satellite navigation system (BDS). However, researches show that the daily life of people takes up 80% -90% of the total time, so when a user wants to position any object in a building or a closed environment, due to the limitation of GNSS and the complexity of the indoor environment, the influence of multipath effect, high-frequency change, shadow effect, non-line-of-sight interference and the like on signals can not be realized to accurately position the signals so as to meet the requirements of the user, and the requirements of indoor positioning service become more and more intense. For example, market demands for indoor positioning technologies in the fields of key building management, intelligent hospital construction, personal services, parking lot vehicle location inquiry, security, and the like are all great.
According to the information source placement position, the existing indoor positioning technology can be divided into two main types: indoor positioning technology based on natural information sources and indoor positioning technology based on external information sources. The indoor positioning technology based on the natural information source comprises inertial navigation, geomagnetic navigation and the like; and the indoor positioning technology based on the external confidence source comprises an infrared positioning technology, an ultrasonic positioning technology, a Bluetooth positioning technology, a WiFi positioning technology, an ultra-wideband (UWB) positioning technology, a Radio Frequency Identification (RFID) positioning technology, a positioning technology based on Frequency Modulation Continuous Wave (FMCW) and the like. The performance indexes of the indoor positioning system are mainly cost and positioning precision, and the current indoor positioning technology is biased, but the two indexes are difficult to be combined, and the control of the cost while the positioning precision is improved as much as possible is a great challenge. The trend in the future will be to combine the technologies, fuse their advantages, and overcome their respective disadvantages. Therefore, the design of the indoor positioning system with high cost performance, easy realization and simple structure has practical significance.
Disclosure of Invention
Aiming at the defects of high cost and high power consumption of the existing indoor positioning technology, the invention aims to provide an indoor positioning method based on signal reflection points, which has the advantages of low cost, low power consumption and easy deployment.
In order to achieve the above purpose, the invention adopts the following technical scheme:
an indoor positioning method based on signal reflection points is realized based on an indoor positioning system, wherein the indoor positioning system comprises an excitation source, a receiver and at least three signal reflection points;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures the signals by receiving signals of the excitation source and a plurality of signal reflection points through a signal processing method and utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the receiver by utilizing a TDOA positioning method.
The positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,/>Channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, the receiver captures the signal by using the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates; assuming that the distance from the excitation source to a certain reflection point is R1, the distance from the reflection point to the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair ofThe frequency estimation is carried out to obtain the distance difference between each signal reflection point and the receiver; the distance difference (R1 +R2) -R can be calculated according to the frequency offset, and the distance difference (R2-R) between an excitation source and a receiver and between a reflection point and the receiver is calculated due to the known R1; and then calculating by using a TDOA positioning method according to a plurality of distances and the positions of the signal reflection points to obtain the position information of the receiver so as to realize the positioning of the target.
An indoor positioning method based on signal reflection points is realized based on an indoor positioning system, wherein the indoor positioning system comprises at least one excitation source, three signal reflection points and a receiver;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures the signals by receiving signals of the excitation source and a plurality of signal reflection points through a signal processing method and utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the excitation source through a TDOA positioning method.
The positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, which is taken when different spread spectrum methods are usedThe values are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase lockingTo the point ofOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, the receiver captures the signal by using the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates; assuming that the distance from the excitation source to a certain reflection point is R1, the distance from the reflection point to the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair ofThe distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, and the distance difference can be calculated according to the frequency offsetCalculating a distance difference (R1 + R2) -R, and calculating a distance difference (R1-R) between an excitation source and a receiver and between the excitation source and a reflection point due to the known R2; and then calculating by using a TDOA positioning method according to the distances and the positions of the signal reflection points to obtain the position information of the excitation source so as to realize the positioning of the target.
An indoor positioning method based on signal reflection points is realized based on an indoor positioning system, wherein the indoor positioning system comprises at least four excitation sources, at least four receivers and one signal reflection point;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures the signals by receiving signals of the excitation source and a plurality of signal reflection points through a signal processing method and utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the signal reflection point by utilizing a TDOA positioning method.
The positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, receiver utilizing spread spectrum codeThe relevant receiving captures the signal to obtain code phase offset and frequency offset estimation, and the receiver can know from which reflection point the path of signal originates; taking one transceiver as an excitation source, taking the rest transceivers as receivers, and assuming that the distance from the transceiver as the excitation source to a certain reflection point is R1, the distance from the reflection point to the transceiver as the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair ofThe distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, the distance difference (R1+R2) -R can be calculated according to the frequency offset, and the distance difference (R1+R2) between the excitation source and the reflection point and between the reflection point and the receiver is calculated due to the known R; and then calculating by using a TDOA positioning method according to a plurality of distances, the determined signal transmitting point sequence numbers and the positions of the transceivers to obtain the position information of the signal reflecting points, so as to realize the positioning of the targets.
After the scheme is adopted, the signal is transmitted through the excitation source, the transmitted signal is received by the signal reflection points, the signal reflection points are subjected to spread spectrum processing through the received signal, the signals of the excitation source and the signal reflection points are finally received by the receiver, the distance difference between the signal reflection points can be obtained through processing the received signals, and the target position can be finally obtained through positioning through a TDOA algorithm. The invention utilizes the characteristics of simple structure, lower cost and easy deployment of the signal reflection points, and can realize a large amount of deployment in an indoor positioning scheme.
Drawings
FIG. 1 is a schematic diagram of a receiver positioning system according to the present invention;
FIG. 2 is a schematic diagram of the present invention for OOK spread spectrum at the signal reflection point
FIG. 3 is a functional block diagram of a receiver positioning system of the present invention;
FIG. 4 is a diagram of receiver positioning distance relationship;
FIG. 5 is a schematic diagram of an excitation source positioning system according to the present invention;
FIG. 6 is a functional block diagram of an excitation source positioning system;
FIG. 7 is a schematic diagram of the relationship between the positioning distances of the excitation sources;
FIG. 8 is a schematic diagram of a signal reflection point positioning system;
FIG. 9 is a functional block diagram of a signal reflection point positioning system;
fig. 10 is a schematic diagram of the relationship between the positioning distances of the signal reflection points.
Detailed Description
The invention discloses an indoor positioning method based on signal reflection points, which is realized based on an indoor positioning system, wherein the indoor positioning system comprises an excitation source, the signal reflection points and a receiver. The description is as follows:
the excitation source, i.e. the signal source, is used for continuously or intermittently transmitting signals, which are obtained by modulating the frequency of a continuous wave, using a linearly modulated FMCW signal. The frequency modulation mode of the FMCW signal comprises two modes of linear frequency modulation and non-linear frequency modulation. In the scheme, a sawtooth wave modulation mode in linear frequency modulation is adopted. The frequency difference between the received signal and the transmitted signal is obtained through the processing of a mixer and a subsequent signal processing module. The time difference between the signal received by the receiver and the local signal is calculated according to the frequency difference.
The signal reflection point is a low-cost signal modulation and amplification unit and consists of a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna. The signal reflection points amplify the received signal, each signal reflection point has a dedicated spread spectrum code, the received signal is modulated by the sequence, and finally the signal reflection points are transmitted to the receiver, and the spread spectrum codes can be used for identifying the identity information of the signal in the subsequent signal processing process.
The receiver captures the signals by receiving signals of the excitation source and a plurality of signal reflection points through a signal processing method and utilizing the correlation receiving of the spread spectrum codes to obtain code phase offset and frequency offset estimation, and separates the reflection signals of each signal reflection point, so that the distance difference between each signal reflection point and the receiver can be calculated.
The indoor positioning system can be divided into a receiver positioning system, a signal reflection point positioning system and an excitation source positioning system according to different positioning scenes, and the three positioning systems are specifically as follows:
as shown in fig. 1, the positions of the excitation source and the signal reflection point in the receiver positioning system are determined, and the position of the receiver is calculated. The system at least needs one excitation source, three reflection points and one receiver. The positioning system is similar to GPS positioning and can be used for positioning factory equipment.
Based on the receiver positioning system, the indoor positioning method comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency.
Step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when the OOK system (the schematic block diagram of which is shown in fig. 2) is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1.It is a complex number, which is the channel gain from the excitation source to the reflection point. />To delay signal propagation from excitation source to reflection pointThe time delay between the input antenna and the output antenna can be consideredIs a kind of medium. w (w) k And (t) is noise.
Step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is the noise of the receiver,and->Multiplied by comparison with w 0 (t) is much smaller and can be directly ignored.
Step 4, by performing synchronous down-conversion processing on the carrier signal received by the receiver (assuming carrier synchronization is obtained and locked, i.e.)) The baseband signal thus obtained is
w b And (t) is equivalent low-pass noise after down-conversion.
Step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d And (t) is noise after synchronous detection.
At the position ofThe region, i.e. within one sweep period, can be obtained
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term.
And 6, the receiver captures the signal by utilizing the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates. Let the distance from the excitation source to a certain reflection point be R1, the distance from the reflection point to the receiver be R2, and the distance from the excitation source to the receiver be R, as shown in fig. 4. For a pair ofAnd obtaining the distance difference between each signal reflection point and the receiver by frequency estimation. The distance can be calculated according to the frequency offsetThe dispersion (R1+R2) -R, since R1 is known, the difference in the distances of the excitation source to the receiver and the reflection point to the receiver (R2-R) can be calculated. And then calculating by using a TDOA positioning method according to a plurality of distances and the positions of the signal reflection points to obtain the position information of the receiver so as to realize the positioning of the target.
As shown in FIG. 5, the positions of the reflection points and the receivers in the excitation source positioning system are determined, and the positions of the excitation sources are calculated. The positioning system requires at least one excitation source, three signal reflection points and one receiver. If the algorithm supports signals such as 4G/5G/WIFI and the like as an excitation source, positioning of a specific mobile phone can be achieved.
As shown in fig. 6, the indoor positioning method based on the excitation source positioning system specifically includes the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Where mod (T, T) denotes T modulo T, T is time, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency.
Step 2, neglecting the influence of channel multipath, the signal is transmitted from the excitation source and received by a certain signal reflection point k (k=1, 2.), each signal reflection point has a special C/A code, and the modulated signal is
wherein dk And (t) is a spread spectrum chip signal, and the value of the signal is different when different spread spectrum methods are adopted. When OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1.For exciting source to reflection point channelGain, which is a complex number. />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>Is a kind of medium. w (w) k And (t) is noise.
Step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
Here, theChannel gain for signal reflection point to receiver, < ->Is the signal propagation delay, alpha 0 ，τ 0 Channel attenuation coefficient and propagation delay from excitation source to receiver, w 0 (t) receiver noise, < >>And->Multiplied by comparison with w 0 (t) is much smaller and can be directly ignored.
Step 4, by performing synchronous down-conversion processing on the carrier signal received by the receiver (assuming carrier synchronization is obtained and locked, i.e.)) The baseband signal thus obtained is
w b And (t) is equivalent low-pass noise after down-conversion.
Step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d And (t) is noise after synchronous detection. At the position ofThe region, i.e. within one sweep period, can be obtained
wherein Is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term.
And 6, the receiver captures the signal by utilizing the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates. Let the distance from the excitation source to a certain reflection point be R1, the distance from the reflection point to the receiver be R2, and the distance from the excitation source to the receiver be R, as shown in fig. 7.
For a pair ofThe distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, the distance difference (R1+R2) -R can be calculated according to the frequency offset, and the distance difference (R1-R) between the excitation source and the receiver and the distance difference between the excitation source and the reflection point can be calculated due to the known R2. And then calculating by using a TDOA positioning method according to the distances and the positions of the signal reflection points to obtain the position information of the excitation source so as to realize the positioning of the target.
As shown in fig. 8, the positions of the excitation source and the receiver in the signal reflection point positioning system are determined, and the positions of the signal reflection points are calculated. Typically, the excitation source and receiver in the system are implemented in a single device, namely a radar transceiver, and the system requires at least four transceivers, namely four excitation sources, four receivers, and a signal reflection point. The system has the advantages that the cost of the signal reflection node is very low, a large number of deployments are supported, and the UWB scheme can be replaced.
As shown in fig. 9, based on the signal reflection point positioning system, the indoor positioning method is as follows:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Where mod (T, T) denotes T modulo T, T is time, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency.
Step 2, neglecting the influence of channel multipath, the signal is transmitted from the excitation source and received by a certain signal reflection point k (k=1, 2.), each signal reflection point has a special C/A code, and the modulated signal is
wherein dk And (t) is a spread spectrum chip signal, and the value of the signal is different when different spread spectrum methods are adopted. When OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1.It is a complex number, which is the channel gain from the excitation source to the reflection point. />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>Is a kind of medium. w (w) k And (t) is noise.
Step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
Here, theChannel gain for signal reflection point to receiver, < ->Is the signal propagation delay, alpha 0 ，τ 0 Channel attenuation coefficient and propagation delay from excitation source to receiver, w 0 (t) receiver noise, < >>And->Multiplied by comparison with w 0 (t) is much smaller and can be directly ignored. />
Step 4, by performing synchronous down-conversion processing on the carrier signal received by the receiver (assuming carrier synchronization is obtained and locked, i.e.)) The baseband signal thus obtained is
w b And (t) is equivalent low-pass noise after down-conversion.
Step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d And (t) is noise after synchronous detection. At the position of The region, i.e. within one sweep period, can be obtained
wherein Is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term.
Step 6: the receiver captures the signal using the correlation reception of the spreading code to obtain a code phase offset and a frequency offset estimate, and the receiver can know from which reflection point the signal originates. In this scheme, one transceiver is taken as an excitation source, the rest transceivers can be taken as receivers, and the distance from the transceiver as the excitation source to a certain reflection point is assumed to be R1, the distance from the reflection point to the transceiver as the receiver is assumed to be R2, and the distance from the excitation source to the receiver is assumed to be R, as shown in fig. 10.
For a pair ofThe distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, the distance difference (R1+R2) -R can be calculated according to the frequency offset, and the distance difference (R1+R2) between the excitation source and the reflection point and between the reflection point and the receiver can be calculated due to the known R. And then calculating by using a TDOA positioning method according to a plurality of distances, the determined signal transmitting point sequence numbers and the positions of the transceivers to obtain the position information of the signal reflecting points, so as to realize the positioning of the targets.
In summary, the signal transmitted by the excitation source is received by the signal reflection points, the signal reflection points receive the signals of the excitation source and the signal reflection points by the receiver finally through spread spectrum processing, the distance difference between the signal reflection points can be obtained through processing the received signals, and the target position can be finally obtained through positioning by adopting a TDOA algorithm. The invention utilizes the characteristics of simple structure, lower cost and easy deployment of the signal reflection points, and can realize a large amount of deployment in an indoor positioning scheme.
The foregoing embodiments of the present invention are not intended to limit the technical scope of the present invention, and therefore, any minor modifications, equivalent variations and modifications made to the above embodiments according to the technical principles of the present invention still fall within the scope of the technical proposal of the present invention.

Claims (3)

1. An indoor positioning method based on signal reflection points is characterized by comprising the following steps: the method is realized based on an indoor positioning system, and the indoor positioning system comprises an excitation source, a receiver and at least three signal reflection points;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures signals by receiving signals of an excitation source and a plurality of signal reflection points through a signal processing method and utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates out the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the receiver by utilizing a TDOA positioning method;
the positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents that T is modulo T, T is the sweep period, and μ is the sweepFrequency rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, the receiver captures the signal by using the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates; assuming that the distance from the excitation source to a certain reflection point is R1, the distance from the reflection point to the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair ofThe frequency estimation is carried out to obtain the distance difference between each signal reflection point and the receiver; the distance difference (R1 +R2) -R can be calculated according to the frequency offset, and the distance difference (R2-R) between an excitation source and a receiver and between a reflection point and the receiver is calculated due to the known R1; and then calculating by using a TDOA positioning method according to a plurality of distances and the positions of the signal reflection points to obtain the position information of the receiver so as to realize the positioning of the target.
2. An indoor positioning method based on signal reflection points is characterized by comprising the following steps: the method is realized based on an indoor positioning system, and the indoor positioning system comprises at least one excitation source, three signal reflection points and one receiver;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures signals of the excitation source and a plurality of signal reflection points through a signal processing method by utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the excitation source by utilizing a TDOA positioning method;
the positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For signal propagation delay from excitation source to reflection pointThe delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, the receiver captures the signal by using the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates; assuming that the distance from the excitation source to a certain reflection point is R1, the distance from the reflection point to the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair ofThe distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, the distance difference (R1+R2) -R can be calculated according to the frequency offset, and the distance difference (R1-R) between the excitation source and the receiver and between the excitation source and the reflection point is calculated due to the known R2; and then calculating by using a TDOA positioning method according to the distances and the positions of the signal reflection points to obtain the position information of the excitation source so as to realize the positioning of the target.
3. An indoor positioning method based on signal reflection points is characterized by comprising the following steps: the method is realized based on an indoor positioning system, and the indoor positioning system comprises at least four excitation sources, at least four receivers and a signal reflection point;
the excitation source is used for continuously or intermittently transmitting signals, linear modulated FMCW signals are adopted, and the signals are obtained by modulating the frequency of continuous waves;
the signal reflection points are composed of four parts, namely a receiving antenna, an amplifier, a spread spectrum module and a transmitting antenna, the signal reflection points amplify received signals, each signal reflection point is provided with a dedicated spread spectrum code, the received signals are modulated by utilizing the sequence, and finally the signals are transmitted to a receiver, and the spread spectrum codes can be used for identifying the identity information of the signals in the subsequent signal processing process;
the receiver captures signals of the excitation source and a plurality of signal reflection points through a signal processing method by utilizing the correlation receiving of a spread spectrum code to obtain code phase offset and frequency offset estimation, separates the reflection signals of each signal reflection point, can calculate the distance difference between each signal reflection point and the receiver, and obtains the position information of the signal reflection point by utilizing a TDOA positioning method;
the positioning method specifically comprises the following steps:
step 1, generating FMCW signals by an excitation source, and setting the transmitting signals as
Wherein mod (T, T) represents T modulo T, T is the sweep period, μ is the sweep rate (Hz/s), f c Is the carrier frequency;
step 2, neglecting the influence of channel multipath, transmitting a transmitting signal from an excitation source, receiving the transmitting signal by a certain signal reflection point k (k=1, 2.), wherein each signal reflection point has a special C/A code, and the modulated signal is
wherein ,dk (t) is a spread spectrum chip signal, and when different spread spectrum methods are adopted, the values of the spread spectrum chip signal are different: when OOK system is adopted, d k (t) a pseudo-random signal having a value of 0 or 1; when BPSK system is used, d k (t) a pseudo-random signal having a value of-1 or 1;the channel gain from the excitation source to the reflection point is a complex number; />For the propagation delay of the signal from the excitation source to the reflection point, the delay between the input antenna to the output antenna of the reflection point can be taken into account +.>In (a) and (b); w (w) k (t) is noise;
step 3, the receiver receives the synthesized signal from the excitation source and the signal reflection point, and the received signal is
wherein ,channel gain for signal reflection point to receiver, < ->Is the signal propagation delay, w 0 (t) is receiver noise;
step 4, the carrier signal received by the receiver is processed by synchronous down-conversion, and the obtained baseband signal is
w b (t) is the equivalent low-pass noise after down-conversion;
step 5, the receiver locally generates an FMCW signal synchronously, performs phase tracking on the baseband signal and performs phase locking toOn the basis of the output after synchronous detection
w d (t) is noise after synchronous detection;
at the position ofAreas, can obtain
wherein ,is a frequency of +.>Is used to determine the sine term of (c),for signal primary phase, ++>Is an OOK/BPSK multiplication term;
step 6, the receiver captures the signal by using the correlation receiving of the spread spectrum code to obtain code phase offset and frequency offset estimation, and the receiver can know the reflection point from which the path of signal originates; taking one transceiver as an excitation source, taking the rest transceivers as receivers, and assuming that the distance from the transceiver as the excitation source to a certain reflection point is R1, the distance from the reflection point to the transceiver as the receiver is R2, and the distance from the excitation source to the receiver is R; for a pair of The distance difference between each signal reflection point and the receiver can be obtained by frequency estimation, the distance difference (R1+R2) -R can be calculated according to the frequency offset, and the distance difference (R1+R2) between the excitation source and the reflection point and between the reflection point and the receiver is calculated due to the known R; and then calculating by using a TDOA positioning method according to a plurality of distances, the determined signal transmitting point sequence numbers and the positions of the transceivers to obtain the position information of the signal reflecting points, so as to realize the positioning of the targets.
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