CN117676811A - Terminal positioning method, system and device applied to mobile cellular communication system - Google Patents
Terminal positioning method, system and device applied to mobile cellular communication system Download PDFInfo
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- 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
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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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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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
- H04W4/029—Location-based management or tracking services
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Abstract
The invention discloses a terminal positioning method, a system and a device applied to a mobile cellular communication system, wherein the method comprises the following steps: acquiring the position and/or the motion state of a wireless access point; estimating Doppler frequency offset between a wireless access point and a terminal to be positioned; and calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point. The method can effectively solve the positioning problem in a mobile scene by measuring the Doppler frequency offset between the wireless access point and the terminal, does not need additional special measurement resources and measurement process, effectively reduces the complexity and cost of positioning and improves the availability and reliability of positioning.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a method, a system, and an apparatus for positioning a terminal applied to a mobile cellular communications system.
Background
The 5G age has also driven the development and application of some new application scenarios. Non-terrestrial satellite communication (NTN, non-Terrestrial Network) is a new feature introduced by 3GPP at Rel-16, and is mainly used for supporting satellites as cellular network access platforms, so as to solve the problem of seamless coverage in remote areas and provide low-cost wide area internet of things access, and promote informatization to develop in a wider and deeper level. The ground stationary satellites in high orbit and the high-speed moving satellites in low orbit are classified according to the satellite orbits and the motion states. Low-orbit satellites have been paid attention to and developed in recent years due to advantages of low deployment cost, small propagation delay, large communication capacity, flexible constellation design, etc., for example, up to 2023, 6 months, and star-link systems have been deployed for more than 4 thousand low-orbit satellites. For satellite wireless access platform, the ground terminal position information plays an important role, and the key processes of user management, radio resource management, mobility switching management and the like all need to use the terminal position. In the 3GPP Rel-16/17/18 system, a terminal needs to have satellite navigation positioning (GNSS, global Navigation Satellite System) capability and report position information when accessing a satellite platform. The 3GPP will push terminals supporting GNSS positioning without access to the satellite platform in a later protocol release (Rel-19), where other positioning techniques are required to determine the position of the terminal.
The terminal position is typically determined by:
1. the time-of-flight based positioning approach, which typically has a relatively high timing clock for the access point, is often difficult for the terminal to guarantee a high performance timing clock. This approach requires a specific reference signal and dedicated measurement slots, and the positioning overhead and delay are high.
2. Positioning based on propagation azimuth, however, is affected by multipath signals, resulting in erroneous azimuth estimates, which are relatively low in reliability.
3. The positioning method based on the electromagnetic environment depends on the effectiveness, reliability and stability of the defined electromagnetic fingerprint and the completeness of the electromagnetic fingerprint map. There is a large uncertainty in both accuracy and reliability, which is typically only available for coarse position estimation and supplementary assistance estimation.
4. Based on the positioning method of determining orbital doppler, a larger estimated bias will result when the satellite orbit stability is low. When the ground terminal is far away from the satellite orbit surface, the Doppler track is flatter, and the position estimation accuracy is more easily affected by noise. In addition, calculating a doppler trajectory for a particular satellite requires calculating a different doppler trajectory using a different satellite estimated position, requiring additional calculation processing.
Disclosure of Invention
According to one aspect of the invention, a method, a system and a device for positioning a terminal applied to a mobile cellular communication system are provided, and the position of the terminal is estimated by using Doppler frequency offset, so that the rapid and reliable positioning of the terminal is realized without additional software or hardware modules and additional measurement resources and measurement processes.
In a first aspect, the present invention discloses a terminal positioning method applied to a mobile cellular communication system, the method comprising the steps of:
acquiring the position and/or the motion state of a wireless access point;
estimating Doppler frequency offset between a wireless access point and a terminal to be positioned;
and calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
In some embodiments, the calculating the terminal position according to the position, the motion state and the doppler frequency offset of the wireless access point includes:
and calculating the relative direction of the terminal relative to a plurality of wireless access points according to the Doppler frequency offset, and calculating the position of the terminal to be positioned according to the position and the motion state of the wireless access points.
In some embodiments, when the wireless access point and the terminal to be positioned are not in the same horizontal plane, the position of the terminal to be positioned is calculated according to the position, the motion state and the doppler frequency offset of the wireless access point, specifically,
estimating a position line of a terminal to be positioned corresponding to the wireless access point according to the Doppler frequency offset of the wireless access point;
and estimating the position of the terminal to be positioned according to the position lines of the wireless access point and the terminal to be positioned.
In some embodiments, estimating a location line of a terminal to be located corresponding to a wireless access point according to a doppler frequency offset of the wireless access point includes:
calculating a motion vector of the wireless access point and an included angle between the wireless access point and a connecting line of the terminal to be positioned according to the motion state data of the wireless access point and the Doppler frequency offset;
determining the intersection line of the cone with the vertex as the position of the wireless access point and the sphere of the earth, and calculating the set of points in the intersection line;
and determining a subset meeting preset conditions in the set, wherein the subset is a position line of the terminal to be positioned corresponding to the wireless access point.
In some embodiments, estimating the position of the terminal to be located according to the position line of the wireless access point and the terminal to be located includes:
the average distance between the candidate position of the terminal to be positioned and all reference points on all position lines is minimized.
In some embodiments, estimating the position of the terminal to be located according to the position line of the wireless access point and the terminal to be located includes:
minimizing the sum of the distances between the candidate position of the terminal to be positioned and all the position lines, wherein the distance between the candidate position and a certain position line is the shortest distance among the distances between all the reference points on the position line and the candidate position; the shortest distance is the linear distance between a reference point and a candidate position, or the length of an arc line between the candidate position and the intersection point of two position lines passes through the candidate position and is perpendicular to the circle of the position line by taking the sphere center of the earth as the midpoint;
the candidate position having the smallest sum of distances from all the position lines is the position of the terminal to be located.
In some embodiments, when the wireless access point and the terminal to be positioned are located in the same area and the same horizontal plane, acquiring the positions and the motion states of at least three wireless access points;
calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point, specifically,
and determining included angles between the speed vector of the terminal to be positioned and the three wireless access points according to the positions of the wireless access points, and calculating the positions of the terminal to be positioned through the included angles and Doppler frequency offset.
In some embodiments, minimizing the sum of the distances of the candidate locations of the terminal to be located and all location lines includes:
wherein,representing all reference points and candidate positions +.>Shortest distance between candidate positions->The position coordinates of the terminal to be positioned are the variables to be solved; the distance may be a straight line distance between two points, or the length of the shortest arc along the earth's surface; />Representing candidate position +.>Distance from the earth center; alpha n Representing satellite correlations corresponding to an nth position lineWeighting coefficients of (2) satisfy->R E The radius of the sphere of the earth, N represents the number of satellites participating in positioning, namely the number of position lines, wherein one satellite corresponds to one position line.
In a second aspect, a terminal positioning system is disclosed, comprising:
the wireless access point acquisition module acquires the position and/or the motion state of the wireless access point;
the Doppler frequency offset acquisition module is used for estimating Doppler frequency offset between the wireless access point and the terminal to be positioned;
and the positioning calculation module calculates the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
In a third aspect, a terminal positioning device is disclosed, the device comprising: a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing a terminal positioning method as defined in any one of the above for use in a mobile cellular communication system when the computer program is executed.
Compared with the prior art, the invention has the beneficial effects that:
the application provides a terminal positioning method, a system and a device applied to a mobile cellular communication system, and the method can effectively solve the positioning problem in a mobile scene by measuring Doppler frequency offset between a wireless access point and a terminal and accurately estimating the position of the terminal. Because Doppler frequency offset is a basic measurement quantity in wireless mobile communication, the method does not need additional special measurement resources and measurement processes, thereby effectively reducing the complexity and cost of positioning and improving the availability and reliability of positioning.
Drawings
Fig. 1 is a flow chart of a terminal positioning method applied to a mobile cellular communication system according to the present invention;
fig. 2 is a schematic flow chart of a positioning method of a terminal with a wireless access point and a terminal to be positioned in the same horizontal plane;
fig. 3 is a schematic diagram of the relative positions of a ground fixed base station and a terminal to be positioned according to the present invention;
fig. 4 is a schematic flow chart of a positioning method provided by the invention, wherein the wireless access point and the terminal to be positioned are not in the same horizontal plane and the wireless access point is one;
FIG. 5 is a schematic diagram of the relative motion between a single satellite and a terrestrial terminal to be located according to the present invention;
fig. 6 is a schematic diagram of an intersection line between a cone provided by the invention and a sphere of the earth, wherein the cone uses a satellite position as a vertex and a vertex angle as the included angle.
Fig. 7 is a schematic flow chart of a positioning method in which a wireless access point and a terminal to be positioned are not located at the same horizontal plane and the number of wireless access points is multiple;
FIG. 8 is a schematic view of the position lines of a plurality of satellites from the view point of the earth's surface looking down in the direction of the earth's center;
FIG. 9 is a schematic diagram of the shortest distance between each position line and a candidate position according to the present invention;
fig. 10 is a schematic structural diagram of a terminal positioning system provided by the present invention.
Detailed Description
For a better understanding and implementation, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules that are expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1, the present application provides a terminal positioning method applied to a mobile cellular communication system, which does not need additional dedicated measurement resources and measurement procedures, effectively reduces the complexity and cost of positioning, and improves the availability and reliability of positioning.
Specifically, the method comprises the following steps:
step S1, the position and/or the motion state of the wireless access point are obtained. There are various types of wireless access points, such as a base station in the same area and level as the terminal to be located, or a satellite in a different plane from the terminal to be located, etc. The position and the motion state of the wireless access point can be calculated through preset information thereof, such as ground station address planning or satellite orbit planning; the position and motion state data of the wireless access point can be directly read through the external satellite positioning system.
The location of a wireless access point typically has a variety of coordinate systems, including STW and UNW. The satellite position needs to be converted into a ground terminal position coordinate system, and the estimation of the position of the terminal to be positioned is completed through the unified coordinate system.
More, when the wireless access point performs orbital motion, the position and motion state data of the wireless access point at the moment of positioning are calculated by reading the orbit information when the position and motion state are obtained by the orbit information. The position of the wireless access point is represented by coordinates in a specific coordinate system, and the motion state is represented by a velocity vector of the wireless access point.
And S2, estimating Doppler frequency offset between the wireless access point and the terminal to be positioned. In the process of communication between the satellite and the ground terminal, doppler frequency offset caused by relative motion needs to be estimated first, and the frequency offset is corrected, so that normal signal receiving and demodulation are completed. The Doppler frequency offset can be estimated by the terminal according to the downlink signal, or by the uplink signal of the wireless access point.
And step S3, calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
Specifically, the relative direction of the terminal relative to a plurality of wireless access points is calculated according to Doppler frequency offset, and the position of the terminal to be positioned is calculated according to the position and the motion state of the wireless access points.
The method is further explained below in terms of the relative positional relationship between the wireless access point and the terminal to be located.
1. As shown in fig. 2, the wireless access point is at the same level as the terminal to be located:
step S21, the position of the wireless access point is obtained. The number of the wireless access points is at least three, and as shown in fig. 3, the relative positions of the ground fixed base station and the terminal to be positioned are shown schematically. The three wireless access points are BS1, BS2, BS3, respectively. The base stations of the terrestrial cellular network typically have fixed and known locations, and the locations of the base stations can be obtained directly from the base station GPS or network configuration data.
And S22, estimating Doppler frequency offset between the wireless access point and the terminal to be positioned. When a terminal to be positioned in a ground mobile cellular communication network is positioned, a wireless access point of the terminal to be positioned is a base station, the terminal to be positioned and the base station are usually in the same area and plane, and the density of the base station is usually larger. In a ground mobile cellular network, the relative movement between a base station and a mobile terminal determines the corresponding Doppler frequency offset.
Without loss of generality, the Doppler frequency offset between the terminal to be positioned and each wireless access point is respectively acquired by taking the connection line of two wireless access points as a horizontal axis and one wireless access point as an origin.
As shown in fig. 3, the line connecting BS2 and BS3 is taken as the X axis, and BS3 is taken as the origin of coordinates. Due to the movement of the UE, i.e. the terminal to be positioned, relative to the BS1/2/3, corresponding Doppler frequency offsets are generated respectively. At theta n Velocity vector v representing UE ue The angle between the UE-BSn connection line, the doppler frequency offset between the UE and the nth base station can be expressed as:
with (x) n ,y n ) The coordinates of the nth base station are represented, (x, y) the position of the UE, and θ the direction angle of the UE velocity vector.
And S23, calculating the position of the terminal to be positioned according to the position of the wireless access point and the Doppler frequency offset.
Specifically, according to the position and the motion state of the wireless access point, determining the included angle between the speed vector of the terminal to be positioned and the three wireless access points, and calculating the position of the terminal to be positioned through the included angle and the Doppler frequency offset.
The terminal positioning problem is the process of determining the terminal coordinates (x, y) by the formula (1) of estimating the doppler frequency offset. The following relationship can be obtained from fig. 3:
θ n ＝min((∠(x n -x,y n -y)-θ),(2π-(∠(x n -x,y n -y)-θ))) (2)
where, the angle (x, y) represents the argument (angle) of the vector (x, y). Substituting the formula (2) into the formula (1), combining the Doppler frequency offsets of the N base stations to obtain an equation system of N equations, and solving the equation system to obtain the position estimation value of the terminal UE to be positionedSpeed vector estimate +.>Thereby completing the positioning estimation of the terminal UE to be positioned.
2. The wireless access point and the terminal to be positioned are not positioned on the same horizontal plane, and the wireless access point is one:
step S41, the position and the motion state of the wireless access point are obtained. Terminal positioning problems in non-terrestrial mobile cellular communication networks are characterized by wireless access points that are typically located high-altitude, e.g., on-board base stations, hereinafter referred to as satellites. Because the wireless access point and the terminal to be positioned are not in the same plane, and the coverage area of a single satellite is large, the relative position relationship between the satellite and the terminal to be positioned in the three-dimensional space is required.
The position and motion state of the satellite can be calculated through the orbit information of the satellite, and can also be obtained through an external satellite positioning system. If the satellite platform has the positioning capability of an external satellite positioning system, the position and the motion state of the satellite are directly read. If satellite orbit information is available, the position and motion state at a specific moment can also be calculated by the orbit information. In this application, the position of a satellite is represented by coordinates in a specific coordinate system, and the motion state is represented by a velocity vector of the satellite.
The satellite positions can be represented by different coordinate systems, but all the satellite positions need to be converted into coordinate systems used for positioning the terminal so as to uniformly calculate related geometric relations, for example, coordinate systems based on longitude, latitude and altitude of the earth.
And S42, estimating Doppler frequency offset between the wireless access point and the terminal to be positioned.
In the communication process of the satellite and the terminal with the positioning function, the relative movement speed is high, so that obvious Doppler frequency offset can be generated, and the processing is needed to ensure the communication performance. Typical processing methods include: the receiving end compensates Doppler frequency offset (post compensation) and the transmitting end compensates Doppler frequency offset (pre-compensation). The two compensation modes first need to estimate Doppler frequency offset. Thus, in satellite communication systems, doppler frequency offset is a commonly available measurement during communication.
The estimate of the doppler frequency offset is related to the number of wireless access points. When the wireless access point is a single satellite, the relative motion between the single satellite and the terrestrial to-be-located terminal is as shown in fig. 5. The Doppler frequency offset of the wireless signal is determined by the relative motion speed of the satellite and the ground terminal. For low-orbit communication satellite communication systems, the motion speed of the low-orbit satellite is usually much greater than that of the ground terminal, so the doppler frequency offset is mainly determined by the moving state of the satellite.
Based on the relative motion of the satellite and the terminal to be positioned on the ground, the calculation formula of the Doppler frequency shift is as follows:
wherein F is c Is the carrier frequency, c is the speed of light,is the rate of change (i.e., relative velocity) of the distance d between the satellite and the terminal. In FIG. 5, V s And V is equal to ue Velocity vectors, θ, of the satellite and ground terminals, respectively s And theta ue The included angles between the satellite speed vector, the terminal speed vector to be positioned and the connection line of the satellite-terminal to be positioned are respectively.
When the satellite moving speed is far greater than the ground terminal moving speed, the ground terminal is approximately considered to be stationary, the Doppler frequency offset is mainly generated by satellite motion, and then the relative moving speed of the satellite and the terminal is as follows:
thus, the Doppler frequency offset of a single satellite relative to a ground terminal is expressed as:
and step S43, calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
Step S431, estimating the position line of the terminal to be positioned corresponding to the wireless access point according to the Doppler frequency offset of the wireless access point.
For a single satellite, the location line may be determined by the satellite and the terminal to be located. The candidate set of locations for the terminal is generally represented by location line LoP. For example, in a conventional positioning method according to propagation delay, the distance between a base station and a terminal is calculated through propagation delay, and for a single base station, the position line of the terminal is a circle with the base station as the center and the distance as the radius. In the positioning method based on propagation delay, the position line is an isochronous delay line, that is, different positions on the position line have the same propagation delay with the base station.
And step 432, estimating the position of the terminal to be positioned according to the position lines of the wireless access point and the terminal to be positioned.
Specifically, according to the motion state data and Doppler frequency offset of the wireless access point, calculating a motion vector of the wireless access point and an included angle between the wireless access point and the connecting line of the terminal to be positioned;
determining the intersection line of the cone with the vertex as the position of the wireless access point and the sphere of the earth, and calculating the set of points in the intersection line;
and determining a subset meeting preset conditions in the set, wherein the subset is a position line of the terminal to be positioned corresponding to the wireless access point.
The following explains the estimation process of the position of the terminal to be located with reference to fig. 6:
based on satellite motion state dataDoppler frequency offset F obtained by measurement d The included angle theta between the satellite motion vector and the connection line of the satellite-terminal can be calculated by the formula (5) s . As shown in fig. 6, a schematic diagram of the intersection line of the cone with the earth sphere using the satellite position as the vertex and the vertex angle as the included angle is shown.
By r i The point vector representing the intersection line is represented in polar form as (|r) in the coordinate system shown in fig. 6 i II, alpha, gamma), wherein alpha is r i Included angle with Z axis, gamma is r i And an included angle between the projection and the Y axis in the XY plane. By r s Representing the satellite current position vector, the following system of equations is solved to obtain a set of points in the intersecting line:
wherein,is a unit vector of satellite velocity vectors, +.>For the point vector r i Pointing to satellite vector r s Unit vector of direction vector of (a), arg (u) vs ,u si ) Representing vector u vs And vector u si Included angle between R E Is the radius of the sphere of the earth. In the solution set of equation system (6), the subset satisfying the following conditions is the position line LoP corresponding to the satellite:
‖r i ‖≤D s (7)
wherein,is the tangential distance of the satellite position to the earth.
The physical meaning of equation (7) is that the intersection of the system of equations of equation (6) is a closed curve, where one part of the closed curve has a direct view path with the satellite and the other part is blocked by the earth sphere. The condition of equation (7) is satisfied by the set of points of the first portion, namely the terminal position line LoP to be located associated with the satellite. The location line determined based on the doppler frequency offset is an equal doppler frequency offset line, i.e., different locations on the location line have the same doppler frequency offset as the satellite.
The position line may be represented as a range of continuous values, e.g., a curve, or as a set of discrete values, e.g., a set of rasterized earth surface position points. In { S ] n N=1, …, N } represents the terminal position line corresponding to the nth satellite, and S is when the position line is represented by a continuous range of values n Representing a continuous geographic location of the earth's surface, any point in the continuous geographic location range being a locating reference point; when the position lines are represented by discrete sets, the terminal position line S corresponding to the nth satellite n Comprises K n Locating reference points, i.e. K n Reference positions, i.e. S n ＝{s n,k ,k＝1,…,K n (s is therein n,k Representing a certain locating reference point on the earth's surface.
3. The wireless access points and the terminal to be positioned are not positioned on the same horizontal plane, and the number of the wireless access points is multiple:
step S71, the position and the motion state of the wireless access point are acquired.
In accordance with the above step S41, a detailed description thereof will be omitted. The difference is that typically a single satellite can determine a position line that is a set of multiple positions, and the position lines of multiple satellites need to be combined to estimate the position of the terminal. Fig. 8 shows a schematic diagram of the position lines of several satellites from the view point of the earth's surface looking down from the direction pointing to the earth's center.
And step S72, estimating Doppler frequency offset between each wireless access point and the terminal to be positioned.
In accordance with the above step S42, a detailed description thereof will be omitted. The difference is that the doppler frequency offset of each satellite needs to be acquired separately.
And step 73, calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
After the position line related to each satellite is obtained, the position line related to the satellite needs to be synthesized, and finally the position of the terminal is estimated. Typically, the reference point on each position line contains information of the actual position of the terminal, as well as some form of deviation (or error). The position with the shortest average distance from the reference positions is determined and used as the geometric center in the meaning of the average distance from the reference positions, and the geometric center is taken as the estimated value closest to the real position of the terminal. Defining different "average distances" yields different methods of position estimation.
It is noted that for ease of expression or ease of solution, different coordinate systems and coordinate representations may be used in determining the position lines and in estimating the position of the terminal from the position lines associated with each satellite, but all describe the same geometric relationship. If the coordinate system of the terminal position line is different from the coordinate system used for calculating the terminal position from the terminal position line, a corresponding conversion is required.
The method for estimating the position of the terminal to be positioned comprises the following two modes:
A. terminal position estimation based on minimization of average distance from all reference points
The minimization variable for all the position lines, i.e. the average distance of the terminal to be positioned from all the reference points on all the position lines, is determined.
Specifically, the process of estimating the terminal position from all the reference points in the N position lines can be described as the following problem:
wherein when the position line is represented in a continuous range mannerWhen representing position lines in discrete sets +.>Represents the kth reference point s in the nth position line n,k And candidate position->Distance between candidate positions->For the position coordinates of the terminal to be located, the variables to be solved, for example, the linear distance between two points, or the length of the shortest arc along the earth's surface; />Representing candidate position +.>Distance from the earth center; alpha n Representing and nth position lineCorresponding satellite-related weighting coefficients, e.g. determining the corresponding weighting coefficient for each satellite based on the signal strength RSRP or signal to noise ratio SINR of the satellite, and satisfying +.>
The minimization variable in the equation (8) is the sum of squares of distances between the position of the terminal to be positioned and all reference positions in all position lines, and its physical meaning is that the terminal position determined according to the equation (8) is the geometric center of all reference points.
B. Terminal position estimation based on minimization of average shortest distance to multiple position lines
Minimizing the sum of the distances between the candidate position of the terminal to be positioned and all the position lines, wherein the distance between the candidate position and a certain position line is the shortest distance among the distances between all the reference points on the position line and the candidate position; the shortest distance is the linear distance between a reference point and a candidate position, or the length of an arc line between the candidate position and the intersection point of two position lines passes through the candidate position and is perpendicular to the circle of the position line by taking the sphere center of the earth as the midpoint; the candidate position having the smallest sum of distances from all the position lines is the position of the terminal to be located.
Specifically, a process of estimating a terminal position from a plurality of position lines can be described as the following problem:
wherein,representing all reference points and candidate positions +.>Shortest distance between candidate positions->The position coordinates of the terminal to be positioned are the variables to be solved; the distance may be a straight line distance between two points, or the length of the shortest arc along the earth's surface; />Representing candidate position +.>Distance from the earth center; alpha n Representing weighting coefficients related to satellites corresponding to the nth position line, for example, determining the weighting coefficient corresponding to each satellite according to the signal strength RSRP or signal-to-noise ratio SINR of the satellite, and satisfying + ∈ ->R E The radius of the sphere of the earth, N represents the number of satellites participating in positioning, namely the number of position lines, wherein one satellite corresponds to one position line.
In equation (9), each position line and candidate position need to be determined firstThe shortest distance between all reference points and candidate positions in the position line>The minimum value of the distance between them is shown in fig. 9.
Generally, the shortest distance from a point to a curve is the distance from the point to a drop foot point on the curve, where the drop foot point on the curve satisfies that the line between the point and the drop foot point is perpendicular to the tangent line of the curve at the drop foot point. The shortest distance in the formula (9) may be the terminal positionDistance to the location line or passing the candidate location about the center of the earth>And perpendicular to the circle of the position line, position +.>And the length of the arc line between the intersection points of the two curves. The two curves are perpendicular to each other, meaning that the tangents to the two curves at the intersection point are perpendicular to each other.
According to the two methods, the position is obtained to be the position estimated value of the terminal to be positioned.
In the method, a cone is formed by a wireless access point and a terminal to be positioned, and the intersection point of each cone surface and the equal Doppler lines of the ground, which are corresponding to a plurality of satellites, is the position of the terminal. In the calculation process, only the position and the motion state of the satellite need be acquired, and initial estimation of the position of the terminal is not needed.
In the traditional calculation method, the position of the terminal needs to be estimated by utilizing the intersecting point of the equal Doppler conical surfaces of a plurality of satellites, and because the conical surfaces are of a three-dimensional structure, the intersecting line of the two conical surfaces is also a three-dimensional line, and theoretically, the intersecting point of a plurality of three-dimensional lines can be influenced by more factors, the estimated deviation is offset in the three-dimensional space, and larger error is generated when the estimated deviation is projected to the ground coordinates. And a larger number of satellites is required, if the number of satellites is less than 4, the error will be amplified infinitely. The earth surface constraint is utilized, and only one or two satellites are needed, so that the influence of three-dimensional space errors on ground coordinates is reduced, and the positioning reliability is improved.
Based on the same inventive concept, the present application further provides a terminal positioning system, as shown in fig. 10, including:
the wireless access point acquisition module acquires the position and/or the motion state of the wireless access point;
the Doppler frequency offset acquisition module is used for estimating Doppler frequency offset between the wireless access point and the terminal to be positioned;
and the positioning calculation module calculates the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
The application provides a terminal positioning method, a system and a device applied to a mobile cellular communication system, wherein the method can effectively solve the positioning problem in a mobile scene by measuring Doppler frequency offset between a wireless access point and a terminal and estimating the position of the terminal. Because Doppler frequency offset is a basic measurement quantity in wireless mobile communication, the method does not need additional special measurement resources and measurement processes, thereby effectively reducing the complexity and cost of positioning and improving the availability and reliability of positioning.
The application also provides a multi-system wireless communication device or electronic equipment, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the terminal positioning method applied to the mobile cellular communication system when executing the computer program.
Embodiments of the present application also provide a non-transitory machine-readable storage medium having stored thereon an executable program which, when executed by a processor, causes the processor to perform the method as provided by the above embodiments. A memory storing executable program code;
a processor coupled to the memory;
the processor invokes executable program code stored in the memory for performing one of the described terminal positioning methods for application to a mobile cellular communication system.
The embodiments of the present invention disclose a computer program product comprising a non-transitory computer readable storage medium storing a computer program and operable to cause a computer to perform a terminal positioning method as described for application to a mobile cellular communication system.
The embodiments described above are illustrative only, and the modules illustrated as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, may be located in one place, or may be distributed over multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above detailed description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course by means of hardware. Based on such understanding, the foregoing technical solutions may be embodied essentially or in part in the form of a software product that may be stored in a computer-readable storage medium including Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), erasable programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), one-time programmable Read-Only Memory (OTPROM), electrically erasable programmable Read-Only Memory (EEPROM), compact disc Read-Only Memory (Compact Disc Read-Only Memory, CD-ROM) or other optical disc Memory, magnetic disc Memory, tape Memory, or any other medium that can be used for computer-readable carrying or storing data.
Finally, it should be noted that: the embodiment of the present invention is disclosed only in the preferred embodiment of the present invention, and is only used for illustrating the technical scheme of the present invention, but not limiting the technical scheme; although the invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that; the technical scheme recorded in the various embodiments can be modified or part of technical features in the technical scheme can be replaced equivalently; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (10)
1. A terminal positioning method for use in a mobile cellular communication system, the method comprising the steps of:
acquiring the position and/or the motion state of a wireless access point;
estimating Doppler frequency offset between a wireless access point and a terminal to be positioned;
and calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
2. The terminal positioning method applied to a mobile cellular communication system according to claim 1, wherein the calculating the terminal position according to the position, the motion state and the doppler frequency offset of the wireless access point comprises:
and calculating the relative direction of the terminal relative to a plurality of wireless access points according to the Doppler frequency offset, and calculating the position of the terminal to be positioned according to the position and the motion state of the wireless access points.
3. The method for locating a terminal in a mobile cellular communication system according to claim 2, wherein when the wireless access point and the terminal to be located are not in the same horizontal plane, the position of the terminal to be located is calculated according to the position, the motion state and the doppler frequency offset of the wireless access point, specifically,
estimating a position line of a terminal to be positioned corresponding to the wireless access point according to the Doppler frequency offset of the wireless access point;
and estimating the position of the terminal to be positioned according to the position lines of the wireless access point and the terminal to be positioned.
4. A terminal positioning method applied to a mobile cellular communication system according to claim 3, wherein estimating the position line of the terminal to be positioned corresponding to the wireless access point according to the doppler frequency offset of the wireless access point comprises:
calculating a motion vector of the wireless access point and an included angle between the wireless access point and a connecting line of the terminal to be positioned according to the motion state data of the wireless access point and the Doppler frequency offset;
determining the intersection line of the cone with the vertex as the position of the wireless access point and the sphere of the earth, and calculating the set of points in the intersection line;
and determining a subset meeting preset conditions in the set, wherein the subset is a position line of the terminal to be positioned corresponding to the wireless access point.
5. The terminal positioning method applied to a mobile cellular communication system according to claim 4, wherein estimating the position of the terminal to be positioned based on the position line of the wireless access point and the terminal to be positioned, comprises:
the average distance between the candidate position of the terminal to be positioned and all reference points on all position lines is minimized.
6. The terminal positioning method applied to a mobile cellular communication system according to claim 4, wherein estimating the position of the terminal to be positioned based on the position line of the wireless access point and the terminal to be positioned, comprises:
minimizing the sum of the distances between the candidate position of the terminal to be positioned and all the position lines, wherein the distance between the candidate position and a certain position line is the shortest distance among the distances between all the reference points on the position line and the candidate position; the shortest distance is the linear distance between a reference point and a candidate position, or the length of an arc line between the candidate position and the intersection point of two position lines passes through the candidate position and is perpendicular to the circle of the position line by taking the sphere center of the earth as the midpoint;
the candidate position having the smallest sum of distances from all the position lines is the position of the terminal to be located.
7. A terminal positioning method applied to a mobile cellular communication system according to claim 2, wherein when the wireless access points and the terminal to be positioned are located in the same area and in the same horizontal plane, the positions and the movement states of at least three wireless access points are obtained;
calculating the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point, specifically,
and determining included angles between the speed vector of the terminal to be positioned and the three wireless access points according to the positions of the wireless access points, and calculating the positions of the terminal to be positioned through the included angles and Doppler frequency offset.
8. A terminal positioning method applied to a mobile cellular communication system according to claim 6, wherein minimizing the sum of the distances of candidate locations of a terminal to be positioned and all location lines comprises:
wherein,representing all reference points and candidate positions +.>Shortest distance between candidate positions->The position coordinates of the terminal to be positioned are the variables to be solved;
the distance may be a straight line distance between two points, or the length of the shortest arc along the earth's surface;representing candidate position +.>Distance from the earth center; alpha n The weighting coefficients representing the satellite correlation corresponding to the nth position line satisfyR E The radius of the sphere of the earth, N represents the number of satellites participating in positioning, namely the number of position lines, wherein one satellite corresponds to one position line.
9. A terminal positioning system, comprising:
the wireless access point acquisition module acquires the position and/or the motion state of the wireless access point;
the Doppler frequency offset acquisition module is used for estimating Doppler frequency offset between the wireless access point and the terminal to be positioned;
and the positioning calculation module calculates the position of the terminal to be positioned according to the position, the motion state and the Doppler frequency offset of the wireless access point.
10. A terminal positioning device, characterized by comprising: a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing a terminal positioning method applied to a mobile cellular communication system as claimed in any one of claims 1 to 8 when the computer program is executed.
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