CN103648161B - Code division multiple access and orthogonal frequency-division multiplexing signal coupling ranging method, device and system - Google Patents

Abstract

The invention discloses a code division multiple access and orthogonal frequency division multiple access signal coupling ranging method, device and system, which can reduce ranging errors and thereby improve positioning accuracy. The shown method includes: receiving a positioning signal sent by an upstream device, the positioning signal simultaneously carries a CDMA signal for positioning and an OFDM signal for positioning, and the positioning signal is transmitted by the upstream device The CDMA signal and the OFDM signal are coupled to obtain the CDMA signal; the positioning signal is analyzed to obtain the CDMA signal; the positioning signal is analyzed to obtain the OFDM signal; ranging is performed according to the CDMA signal and the OFDM signal. The ranging method, device and system provided by the embodiments of the present invention for coupling CDMA and OFDM signals realize simultaneous The CDMA signal and the OFDM signal are used for ranging, so that the ranging error can be reduced and the positioning accuracy can be improved.

Description

Code division multiple access and orthogonal frequency division multiple access signal coupling ranging method, device and system

technical field

The invention relates to the field of computers, in particular to a method, device and system for coupling distance measurement of code division multiple access and orthogonal frequency division multiple access signals.

Background technique

Location-based services have widely entered people's lives and become an indispensable part of economic construction and social life. For example, indoor positioning technologies based on wireless fidelity (Wireless Fidelity, Wi-Fi), ultra wideband (Ultra Wideband, UWB), pseudolite and other systems have been partially applied, and can be used in environments that are relatively close to nodes (generally within tens of within meters) to achieve positioning.

When implementing positioning services, ranging is often required, and ranging errors affect positioning accuracy. Therefore, how to reduce the ranging error to improve the positioning accuracy is a problem that needs to be solved at present.

Contents of the invention

Embodiments of the present invention provide a method, device and system for coupling distance measurement between code division multiple access and orthogonal frequency division multiple access signals, which can reduce distance measurement errors and thereby improve positioning accuracy.

The embodiment of the present invention adopts following technical scheme:

A code division multiple access and orthogonal frequency division multiple access signal coupling ranging method, comprising:

receiving a positioning signal sent by an upstream device, the positioning signal simultaneously carries a code division multiple access CDMA signal for positioning and an orthogonal frequency division multiple access OFDM signal for positioning, and the positioning signal is transmitted by the upstream device to the The CDMA signal and the OFDM signal are coupled to obtain;

analyzing the positioning signal to obtain the CDMA signal;

analyzing the positioning signal to obtain the OFDM signal;

performing ranging according to the CDMA signal and the OFDM signal;

Performing ranging according to the CDMA signal and the OFDM signal includes:

Using the CDMA signal to capture the first path and the multipath outside the chip, and track the first path and the multipath signal outside the chip through the CDMA signal, and reproduce the first path and the multipath signal outside the chip;

Calculate the multipath error correction item according to the multipath signal reproduction result;

Correcting the frequency-domain code sequence obtained by performing FFT on the received signal according to the multipath error correction item;

Perform pseudorange calculation based on the corrected received signal;

According to the multipath signal reproduction result, calculating the multipath error correction term includes: according to the multipath signal reproduction result, applying the following formula to calculate the multipath error correction term,

Among them, q is the number of off-chip multipaths obtained by CDMA tracking, d _i represents the code used by the i-th subcarrier of the OFDM signal; j represents the imaginary part; T is the time length of OFDM ranging compliance; τ′ ₀ is the first The difference between the actual time delay of the path signal and τ0, A _p is the signal amplitude of the pth path; τ _p is the time delay of the pth path signal;

According to the multipath error correction item, correcting the frequency domain code sequence obtained by performing FFT on the received signal includes: according to the multipath error correction item, applying the following formula to perform the frequency domain code sequence obtained by performing FFT on the received signal fix,

Z _i =Y _i (X _i -Δ _i ) ^* ;

in, is the conjugate of the complex sequence Xi; Y _i is the frequency-domain code sequence on each subcarrier _.

A code division multiple access and orthogonal frequency division multiple access signal coupling ranging device, comprising:

A receiving module, configured to receive a positioning signal sent by an upstream device, the positioning signal simultaneously carries a CDMA signal for positioning and an OFDM signal for positioning, and the positioning signal is combined by the upstream device with the CDMA signal and the The OFDM signal is coupled to obtain;

A first parsing module, configured to parse the positioning signal to obtain the CDMA signal;

A second parsing module, configured to parse the positioning signal to obtain the OFDM signal;

a ranging module, configured to perform ranging according to the CDMA signal and the OFDM signal;

The ranging module is used to use the CDMA signal to capture the first path and multipath outside the chip, and to track the first path and multipath outside the chip through the CDMA signal, and to reproduce the first path and multipath outside the chip. path signal; according to the multipath signal reproduction result, calculate the multipath error correction item; according to the multipath error correction item, correct the frequency domain code sequence obtained by performing FFT on the received signal; based on the corrected received signal, perform pseudo distance calculation;

The ranging module applies the following formula to calculate the multipath error correction item,

Among them, q is the number of off-chip multipaths obtained by CDMA tracking, d _i represents the code used by the i-th subcarrier of the OFDM signal; j represents the imaginary part; T is the time length of OFDM ranging compliance; τ′ ₀ is the first The difference between the actual time delay of the path signal and τ0, A _p is the signal amplitude of the pth path; τ _p is the time delay of the pth path signal;

The ranging module is used to correct the frequency-domain code sequence obtained by performing FFT on the received signal according to the multipath error correction item and applying the following formula,

Z _i =Y _i (X _i -Δ _i ) ^* ;

in, is the conjugate of the complex sequence Xi; Y _i is the frequency-domain code sequence on each subcarrier _.

A code division multiple access and orthogonal frequency division multiple access signal coupling ranging system, including upstream equipment and ranging devices, wherein:

The upstream device is used to couple the CDMA signal used for positioning and the OFDM signal used for positioning to generate a positioning signal that simultaneously carries the CDMA signal and the CDMA signal; transmit the positioning signal to the distance measuring device Signal;

The distance measuring device is the distance measuring device described above.

Based on the above technical solution, the ranging method, device and system of the embodiment of the present invention coupled with CDMA and OFDM signals receive the CDMA signal for positioning and the OFDM signal for positioning sent by the upstream equipment. The positioning signal of the signal; analyzing the positioning signal to obtain the CDMA signal; analyzing the positioning signal to obtain the OFDM signal; performing ranging according to the CDMA signal and the OFDM signal. In this way, by receiving the positioning signal carrying the CDMA signal for positioning and the OFDM signal for positioning at the same time, the CDMA signal and the OFDM signal are used for ranging at the same time, thereby reducing the ranging error and improving the positioning accuracy.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a flow chart of a ranging method for coupling CDMA and OFDMA signals provided in Embodiment 1 of the present invention;

FIG. 2 is a schematic diagram of the structure of the CDMA and OFDMA signal coupling distance measuring device provided by Embodiment 2 of the present invention;

FIG. 3 is a flow chart of a ranging method for coupling CDMA and OFDMA signals provided in Embodiment 2 of the present invention;

FIG. 4a is a schematic structural diagram of an OFDM signal data frame provided by Embodiment 2 of the present invention;

FIG. 4b is a schematic structural diagram of a positioning signal provided by Embodiment 2 of the present invention;

Fig. 4c is a schematic diagram of the OFDM ranging signal multiplexing method provided by Embodiment 2 of the present invention;

FIG. 5 is a schematic structural diagram of a CDMA and OFDMA signal coupling ranging device provided in Embodiment 3 of the present invention;

FIG. 6 is a flowchart of a positioning message transmission method provided in Embodiment 4 of the present invention;

FIG. 7 is a schematic structural diagram of a positioning message transmission device provided in Embodiment 5 of the present invention;

FIG. 8 is a schematic structural diagram of a CDMA and OFDMA signal coupling ranging system provided in Embodiment 6 of the present invention;

FIG. 9 is a schematic diagram of a comparison between CDMA and OFDM multipath error envelopes in an embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1

As shown in Figure 1, the CDMA and OFDMA signal coupling ranging method provided by an embodiment of the present invention includes:

110. Receive a positioning signal sent by an upstream device, the positioning signal simultaneously carries a CDMA (Code Division Multiple Access, Code Division Multiple Access) signal for positioning and an OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiple Access) signal for positioning , the positioning signal is obtained by the upstream device coupling the CDMA signal and the OFDM signal.

120. Analyze the positioning signal to obtain the CDMA signal.

130. Analyze the positioning signal to obtain the OFDM signal.

140. Perform ranging according to the CDMA signal and the OFDM signal.

The execution subject of the above-mentioned 110-140 may be a ranging device, and the device may include multiple modules or devices to implement the above-mentioned method.

The ranging method of the embodiment of the present invention receives the positioning signal sent by the upstream device and carries the CDMA signal for positioning and the OFDM signal for positioning; analyzes the positioning signal to obtain the CDMA signal; analyzes the positioning signal to obtain the OFDM signal; according to the CDMA signal and OFDM signal for ranging. In this way, by receiving the positioning signal carrying the CDMA signal for positioning and the OFDM signal for positioning at the same time, the CDMA signal and the OFDM signal are used for ranging at the same time, so that the ranging error can be reduced and the positioning accuracy can be improved.

Example 2

This embodiment takes the ranging device architecture coupled with CDMA and OFDMA signals shown in FIG. 2 as an example, and describes the specific implementation process of the ranging method in the embodiment of the present invention in detail. The illustrated application scenarios are only to facilitate understanding of the ranging method in the embodiment of the present invention, and should not be regarded as limiting the embodiment of the present invention.

The distance measuring device framework of CDMA and OFDMA signal coupling shown in Figure 2 includes: CDMA signal detection module 21, for detecting and analyzing CDMA signals; weak energy CDMA signal tracking module 22, for tracking The weak energy CDMA signal in the positioning signal; the OFDM symbol demodulation module 23 is used to demodulate the OFDM symbol; the OFDM ranging signal detection module 24 is used to detect the OFDM ranging signal.

For CDMA signals, when the multipath time delay exceeds (1+d) chips, the multipath will not affect the ranging, where d is the distance between CDMA correlators. For OFDM, the impact of short-time-delay multipath on ranging is smaller than that of CDMA signals, but long-time-delay multipath that has no impact on CDMA ranging will still have an impact on OFDM ranging. Therefore, it is possible to combine the advantages of both to reduce multipath errors.

As shown in FIG. 3 , the ranging method for coupling CDMA and OFDMA signals provided in this embodiment includes:

210. The ranging device receives a positioning signal sent by an upstream device, the positioning signal simultaneously carries a CDMA signal for positioning and an OFDM signal for positioning, and the positioning signal is obtained by coupling the CDMA signal and the OFDM signal by the upstream device .

In the embodiment of the present invention, when constructing the structure of positioning signals (such as TC-OFDM signals), under the premise of not affecting the normal OFDM business, CDMA navigation signals are added to realize the same frequency co-carriage of CDMA and OFDM signals, and the CDMA navigation signals It is the main channel for ranging, with the aid of OFDM signal, through the coupling of CDMA and OFDM signal, the accuracy of wireless ranging in multipath and other environments is improved.

As shown in Figure 4a, the OFDM traffic channel is composed of a three-level system of frames, time slots, beacons and OFDM symbols. A frame is composed of multiple time slots, and each time slot includes beacons and multiple OFDM symbols. Among them, Beacons are used for system synchronization and base station identification, and service information is carried by OFDM symbols. In TC-OFDM signal design, the correct reception of OFDM symbols cannot be affected to ensure the normal operation of existing services.

Optionally, the CDMA signal includes a CDMA pilot frequency, a CDMA navigation signal carrying navigation messages, the OFDM signal includes an OFDM ranging signal, at least one OFDM symbol, and the positioning signal includes a beacon part and a data bearing part. In the above step 110, the Coupling the CDMA signal for positioning and the OFDM signal for positioning, when generating the positioning signal, the CDMA pilot and the OFDM ranging signal can be carried in the beacon part, and the at least one OFDM symbol and the CDMA navigation The signal is carried in the data bearing part to generate the positioning signal.

For example, the signal structure of each time slot of the positioning signal in the embodiment of the present invention is shown in Fig. 4b.

The positioning signal (such as TC-OFDM signal) does not change the frame structure of the existing service system, but makes a new design for the existing beacon part. Since OFDM signals and CDMA signals have complementary characteristics in multipath channel ranging, the beacon part, in addition to using CDMA pilots for system synchronization, also sets aside a period of time to carry OFDM ranging signals for coupling ranging with CDMA. Improve ranging accuracy in multipath environments. The low-energy CDMA navigation signal is superimposed on the rest of the OFDM symbol, and the time and frequency measurement can be carried out through long-time integration, and the navigation message can be carried. The CDMA navigation signal and OFDM symbols carrying normal services are carried at the same time and on the same frequency, and the signal energy is controlled so that it does not affect the normal reception of OFDM symbols.

The description of the role of each part of the signal in the positioning structure shown in Figure 4b is as follows:

CDMA pilot: Occupies part of the time in the beacon, using short pseudocode sequences for fast time synchronization of time slot signals. Different base stations are distinguished by different spreading codes. CDMA pilots can choose Gold codes with good autocorrelation and cross-correlation characteristics, and the code length can be designed according to the available time length of beacons and system bandwidth according to beacons.

OFDM ranging signal: used for OFDM ranging method for fine fractional delay measurement and carrier frequency estimation. The OFDM ranging signal is set with a specific code sequence in the frequency domain, and after being modulated by IFFT (Inverse Fast Fourier Transform, Inverse Fast Fourier Transform), the signal is sent in the time domain. Different base station signals are distinguished by different times, and each time slot can be configured with k base station signals according to the available time of the beacon, as shown in Figure 4c. OFDM ranging signals can be used to complement CDMA navigation signals to improve the ranging accuracy of the system in complex environments. (k=3 can be selected in the embodiment)

Weak energy CDMA navigation signal: It can be used for fine synchronization of system carrier; CDMA long-time integration and fine tracking and ranging; navigation message bearing. This part of the signal is sent at the same frequency and at the same time as the OFDM symbol with low energy. Its energy does not affect the normal demodulation of the OFDM symbol, but it can obtain a high integral gain by integrating the CDMA signal for a long time to realize CDMA tracking and ranging and broadcasting of navigation messages. . (CDMA navigation signal weak and OFDM signal 18dB can be selected in the embodiment)

OFDM symbol: The modulation mode of the OFDM service symbol of the existing system is not changed, and the compatibility of the service receiving part of the system is guaranteed.

The navigation message is carried by the weak energy CDMA navigation signal. In order to ensure sufficient spreading gain, according to the time slot length of different OFDM service systems, one or more time slots can carry 1-bit message information. Each frame of navigation message information includes the complete information necessary for navigation. From the perspective of system consistency, it is best to maintain an integer multiple relationship between the navigation message frame and the OFDM service frame in terms of time length. In the embodiment of the present invention, the navigation message includes at least one of the following:

Base station number, base station coordinates, fixed delay correction parameters, clock error compensation parameters, OFDM ranging signal parameters, barometric altimeter correction parameters, synchronization information, calibration information.

Among them, the base station number is used for identification of the base station; the coordinates of the base station are used to indicate the position of the center phase point of the transmitting antenna of the base station; Delay error; the clock error compensation parameter is used to compensate the clock synchronization error of the base station; the OFDM ranging signal parameter, the time slot number of the OFDM ranging signal and the time period in the slot; the air pressure altimeter correction parameter , used for barometric altimetry error correction by the terminal; the synchronization and verification are used for frame synchronization and frame verification of navigation messages.

220. The ranging device determines the initial code phase and carrier frequency of the CDMA signal.

For example, the CDMA signal detection module 21 detects the CDMA pilot signal, realizes the coarse synchronization of the system through time domain correlation, and provides the integrated initial code phase and carrier frequency for weak energy CDMA navigation signal tracking.

230. The ranging device obtains the transmission delay of the CDMA signal according to the initial code phase and the carrier frequency of the CDMA signal.

For example, the CDMA signal detection module 21 obtains the transmission delay of the CDMA signal according to the initial code phase and carrier frequency of the CDMA signal.

240. The ranging device tracks the CDMA signal according to the initial code phase and carrier frequency of the CDMA signal, obtains the time and frequency synchronization information, and demodulates the navigation message.

For example, the weak-energy CDMA signal tracking module 22 integrates and tracks the weak-energy CDMA navigation signal for a long time to obtain more detailed time and frequency synchronization information, and demodulates the navigation message.

Preferably, during the tracking process, the multipath outside the chip can be reproduced and provided to the OFDM ranging signal detection unit to improve the ranging capability of the OFDM ranging signal detection unit in a multipath environment.

250. The distance measuring device determines the time slot where the OFDM signal is located according to the navigation message, and performs delay measurement for the time slot where the OFDM signal is located according to the time-frequency synchronization information to obtain a transmission delay of the OFDM signal.

For example, the OFDM ranging signal detection module 24 determines the corresponding time in the time slot number of the OFDM ranging signal according to the navigation message, based on the time and frequency synchronization information obtained by the CDMA navigation signal, the specified time slot and The OFDM ranging signal at the frequency position is used for fine delay measurement. During the measurement process, multipath interference mitigation can be performed through the multipath information obtained by the CDMA navigation signal tracking unit.

Optionally, when the ranging device parses the positioning signal to obtain the OFDM signal, it may parse and obtain OFDM service information according to the time-frequency synchronization information.

For example, the OFDM symbol demodulation module 23 performs OFDM symbol demodulation based on the time and frequency synchronization information obtained from the CDMA navigation signal to obtain OFDM service information.

Further, in this embodiment, the fine delay measurement information obtained by the OFDM ranging signal detection module 24 is fed back to the weak signal CDMA navigation signal tracking module, so as to improve the ranging accuracy of the CDMA navigation signal.

260. The ranging device performs ranging according to the CDMA signal and the OFDM signal.

First, use the CDMA pilot in the positioning signal (such as TC-OFDM signal) to capture the first path and multipath outside the chip, and track the first path and multipath outside the chip through the CDMA pilot signal to reproduce the first path And multi-path signals outside the chip, so that the reproduced first-path signal amplitude A ₀ , time delay τ ₀ , carrier frequency ω ₀ and phase θ ₀ , the p-th path signal amplitude A _p , time delay τ _p . In indoor positioning, it can be considered that the carrier frequency of each path is the same.

Use ω ₀ and θ ₀ for the carrier frequency mixing of TC-OFDM received signals, combine τ ₀ with the time slot position and frequency band of the OFDM ranging signal given in the navigation message, and perform FFT on the window of the OFDM ranging signal (Fast Fourier Transform, fast Fourier transform), the frequency domain signal is obtained as formula (1-1).

Among them, A ₀ is the amplitude of the first path signal; d _i represents the code used by the ith subcarrier of the OFDM ranging signal, and d _i is preferably 1 or -1; j represents the imaginary part; T is the time length of OFDM ranging; τ′ ₀ is the difference between the actual time delay of the first path signal and τ0, A _p is the signal amplitude of the pth path; τ _p is the time delay of the pth path signal.

According to the existing OFDM ranging method, N-point FFT is performed on the local signal sequence y _k , k∈(0,N-1), to obtain the frequency domain code sequence Y _i on each subcarrier. Then τ' can be calculated by formula (1-2) to formula (1-5).

Among them, Z _i is an intermediate value obtained according to the definition of (1-2 ₎ ; X _i * is the conjugate of the complex number sequence Xi; Y _i is the frequency domain code sequence on each subcarrier; L is the frequency domain correlation interval, This parameter is adjustable; N is the number of subcarriers. The final pseudorange obtained is:

r=c(τ′+τ ₀ )

(1-6)

Among them, c is the speed of light, and τ' is the time delay calculated according to (1-5).

In the present invention, according to the multipath signal reproduction result, the influence of the multipath signal in formula (1-1) is alleviated, and the multipath error correction item is calculated

Among them, q is the number of extra-chip multipaths obtained by CDMA tracking. to receive signal The frequency-domain code sequence X _i obtained by FFT is corrected, and (1-2) is rewritten as

Z _i =Y _i (X _i -Δ _i ) ^* (1-8)

And bring Z _i obtained from formula (1-8) into (1-3) to formula (1-6) to calculate the pseudo-range. Through this modification, the CDMA signal has strong resolving power of extra-chip multipath to eliminate the interference of extra-chip multipath to OFDM ranging signal, so that OFDM ranging can be used in short-delay multipath environment with small ranging error. Advantages, improve the comprehensive ranging capability in multi-path environment.

The ranging method of the embodiment of the present invention receives the positioning signal sent by the upstream device and carries the CDMA signal for positioning and the OFDM signal for positioning; analyzes the positioning signal to obtain the CDMA signal; analyzes the positioning signal to obtain the OFDM signal; according to the CDMA signal and OFDM signal for ranging. In this way, by receiving the positioning signal carrying the CDMA signal for positioning and the OFDM signal for positioning at the same time, the CDMA signal and the OFDM signal are used for ranging at the same time, so that the ranging error can be reduced and the positioning accuracy can be improved.

Example 3

As shown in Figure 5, the CDMA and OFDMA signal coupling ranging device provided in this embodiment includes:

The receiving module 41 is configured to receive a positioning signal sent by an upstream device, the positioning signal simultaneously carries a CDMA signal for positioning and an OFDM signal for positioning, and the positioning signal is obtained by coupling the CDMA signal and the OFDM signal by the upstream device;

The first analysis module 42 is used to analyze the positioning signal to obtain the CDMA signal;

The second analysis module 43 is used to analyze the positioning signal to obtain the OFDM signal;

The ranging module 44 is configured to perform ranging according to CDMA signals and OFDM signals.

Optionally, the ranging module 44 is used to use the CDMA signal to perform first-path and multi-path acquisition outside the chip, and to track the first-path and multi-path signals outside the chip through the CDMA signal, and to reproduce the first-path and multi-path signals outside the chip. multipath signal outside the chip; calculate the multipath error correction item according to the multipath signal reproduction result; according to the multipath error correction item, correct the frequency domain code sequence obtained by performing FFT on the received signal; based on the corrected receiving signal for pseudorange calculation.

Optionally, the ranging module applies the following formula to calculate the multipath error correction item,

Among them, q is the number of off-chip multipaths obtained by CDMA tracking, d _i represents the code used by the i-th subcarrier of the OFDM signal; j represents the imaginary part; T is the time length of OFDM ranging compliance; τ′ ₀ is the first The difference between the actual time delay of the path signal and τ0, A _p is the signal amplitude of the pth path; τ _p is the time delay of the pth path signal;

The ranging module 44 is used to correct the frequency-domain code sequence obtained by performing FFT on the received signal according to the multipath error correction item, by applying the following formula,

Z _i =Y _i (X _i -Δ _i ) ^* ;

in, is the conjugate of the complex sequence Xi; Y _i is the frequency-domain code sequence on each subcarrier _.

Optionally, the first parsing module 42 is specifically configured to determine the initial code phase and carrier frequency of the CDMA signal; obtain the CDMA signal transmission delay according to the initial code phase and carrier frequency of the CDMA signal.

Optionally, the first parsing module 42 is also used to track the CDMA signal according to the initial code phase and carrier frequency of the CDMA signal, obtain time and frequency synchronization information, and demodulate the navigation message.

Optionally, the second parsing module 43 is specifically used to determine the time slot where the OFDM signal is located according to the navigation message; perform time delay measurement on the time slot where the OFDM signal is located according to the time and frequency synchronization information to obtain the transmission time delay of the OFDM signal .

The distance measuring device in the embodiment of the present invention can realize the above-mentioned method embodiment. The components of the device and the functions of each module are only briefly described. For detailed description, please refer to the above-mentioned method embodiment.

The ranging device in the embodiment of the present invention receives the positioning signal sent by the upstream equipment and carries the CDMA signal for positioning and the OFDM signal for positioning; analyzes the positioning signal to obtain the CDMA signal; analyzes the positioning signal to obtain the OFDM signal; according to the CDMA signal and OFDM signal for ranging. In this way, by receiving the positioning signal carrying the CDMA signal for positioning and the OFDM signal for positioning at the same time, the CDMA signal and the OFDM signal are used for ranging at the same time, so that the ranging error can be reduced and the positioning accuracy can be improved.

Example 4

As shown in FIG. 6, an embodiment of the present invention provides a positioning message transmission method, which may include:

610. Couple the CDMA signal and the OFDM signal used for positioning to generate a positioning signal that simultaneously carries the CDMA signal and the OFDM signal.

620. Transmit the positioning signal to the positioning terminal, so that the positioning signal realizes positioning.

The executor of this embodiment may be a positioning message transmission device, and the device may include multiple modules or devices to implement the foregoing method.

In the positioning message transmission method of this embodiment, the positioning signal carrying the CDMA signal and the OFDM signal is generated by coupling the CDMA signal and the OFDM signal used for positioning; the positioning signal is transmitted to the positioning terminal, so that the positioning signal realizes positioning. In this way, the positioning signal carries the CDMA signal and the OFDM signal at the same time, which can improve the signal quality, so that the positioning terminal can use the CDMA signal and the OFDM signal for positioning, thereby improving the positioning accuracy.

In the embodiment of the present invention, when constructing the mechanism of positioning signals (such as TC-OFDM signals), under the premise of not affecting the normal OFDM business, CDMA navigation signals are added to realize the same frequency co-carriage of CDMA and OFDM signals, and the CDMA navigation signals It is the main channel for ranging, with the aid of OFDM signal, through the coupling of CDMA and OFDM signal, the accuracy of wireless ranging in multipath and other environments is improved.

As shown in Figure 4a, the OFDM traffic channel is composed of a three-level system of frames, time slots, beacons and OFDM symbols. A frame is composed of multiple time slots, and each time slot includes beacons and multiple OFDM symbols. Among them, Beacons are used for system synchronization and base station identification, and service information is carried by OFDM symbols. In TC-OFDM signal design, the correct reception of OFDM symbols cannot be affected to ensure the normal operation of existing services.

Optionally, the CDMA signal includes a CDMA pilot and a CDMA navigation signal carrying navigation messages, the OFDM signal includes an OFDM ranging signal, an OFDM symbol for carrying communication services, and the positioning signal includes a beacon part and a data bearing part, In the above 610, the CDMA signal and the OFDM signal used for positioning are coupled, and when the positioning signal is generated, the CDMA pilot frequency and the OFDM ranging signal can be carried in the beacon part, and the OFDM symbol used to carry the communication service can be carried And the CDMA navigation signal is carried in the data bearing part to generate the positioning signal.

For example, the signal structure of each time slot of the positioning signal in the embodiment of the present invention is shown in Fig. 4b.

The positioning signal (such as TC-OFDM signal) does not change the frame structure of the existing service system, but makes a new design for the existing beacon part. Since OFDM signals and CDMA signals have complementary characteristics in multipath channel ranging, the beacon part, in addition to using CDMA pilots for system synchronization, also sets aside a period of time to carry OFDM ranging signals for coupling ranging with CDMA. Improve ranging accuracy in multipath environments. The low-energy CDMA navigation signal is superimposed on the rest of the OFDM symbol, and the time and frequency measurement can be carried out through long-time integration, and the navigation message can be carried. The CDMA navigation signal and OFDM symbols carrying normal services are carried at the same time and on the same frequency, and the signal energy is controlled so that it does not affect the normal reception of OFDM symbols.

The description of the role of each part of the signal in the positioning structure shown in Figure 4b is as follows:

CDMA pilot: Occupies part of the time in the beacon, using short pseudocode sequences for fast time synchronization of time slot signals. Different base stations are distinguished by different spreading codes. CDMA pilots can choose Gold codes with good autocorrelation and cross-correlation characteristics, and the code length can be designed according to the available time length of beacons and system bandwidth according to beacons.

OFDM ranging signal: used for OFDM ranging method for fine fractional delay measurement and carrier frequency estimation. The OFDM ranging signal is set with a specific code sequence in the frequency domain, and after being modulated by IFFT, the signal is sent in the time domain. Different base station signals are distinguished by different times, and each time slot can be configured with k base station signals according to the available time of the beacon, as shown in Figure 4c. OFDM ranging signals can be used to complement CDMA navigation signals to improve the ranging accuracy of the system in complex environments. (For example, k=3 can be selected)

Weak energy CDMA navigation signal: It can be used for fine synchronization of system carrier; CDMA long-time integration and fine tracking and ranging; navigation message bearing. This part of the signal is sent at the same frequency and at the same time as the OFDM symbol with low energy. Its energy does not affect the normal demodulation of the OFDM symbol, but it can obtain a high integral gain by integrating the CDMA signal for a long time to realize CDMA tracking and ranging and broadcasting of navigation messages. . (For example, weak CDMA navigation signal and 15dB OFDM signal can be selected).

OFDM symbol: The modulation mode of the OFDM service symbol of the existing system is not changed, and the compatibility of the service receiving part of the system is guaranteed.

Further optionally, when the above-mentioned OFDM symbols for carrying communication services and the CDMA navigation signal are carried in the data bearing part, the OFDM symbols for carrying communication services and the CDMA navigation signal of the data bearing part may be carried simultaneously , and the same frequency are carried in the data bearing part.

For example, some signals of weak energy CDMA navigation signals are transmitted at the same frequency and at the same time as OFDM symbols with low energy. The energy does not affect the normal demodulation of OFDM symbols, but high integral gain can be obtained by long-term integration of CDMA signals to realize CDMA tracking. Ranging and broadcasting of navigation messages.

Optionally, the above-mentioned carrying the OFDM symbol used to carry the communication service and the CDMA navigation signal before the data carrying part further includes:

The strength of the CDMA navigation signal is adjusted according to the signal strength of the OFDM symbols used to carry communication services.

In the embodiment of the present invention, the navigation message is carried by a weak-energy CDMA navigation signal. In order to ensure sufficient spreading gain, one or more time slots can carry 1-bit message information according to the time slot lengths of different OFDM service systems. Each frame of navigation message information includes the complete information necessary for navigation. From the perspective of system consistency, it is best to maintain an integer multiple relationship between the navigation message frame and the OFDM service frame in terms of time length. Optionally, the navigation message in this embodiment of the present invention includes at least one of the following:

Base station number, base station coordinates, fixed delay correction parameters, clock error compensation parameters, OFDM ranging signal parameters, barometric altimeter correction parameters, synchronization information, calibration information.

Among them, the base station number is used for identification of the base station; the coordinates of the base station are used to indicate the position of the center phase point of the transmitting antenna of the base station; Delay error; the clock error compensation parameter is used to compensate the clock synchronization error of the base station; the OFDM ranging signal parameter, the time slot number of the OFDM ranging signal and the time period in the slot; the air pressure altimeter correction parameter , used for barometric altimetry error correction by the terminal; the synchronization and verification are used for frame synchronization and frame verification of navigation messages.

In the positioning message transmission method of this embodiment, the positioning signal carrying the CDMA signal and the OFDM signal is generated by coupling the CDMA signal and the OFDM signal used for positioning; the positioning signal is transmitted to the positioning terminal, so that the positioning signal realizes positioning. In this way, the positioning signal carries the CDMA signal and the OFDM signal at the same time, which can improve the signal quality, so that the positioning terminal can use the CDMA signal and the OFDM signal for positioning, thereby improving the positioning accuracy.

Example 5

As shown in FIG. 7, the positioning message transmission device provided by an embodiment of the present invention includes:

A generating module 71, configured to couple the CDMA signal and the OFDM signal used for positioning, and generate a positioning message that simultaneously carries the CDMA signal and the OFDM signal;

The transmission module 72 is configured to transmit the positioning message to the positioning terminal, so that the positioning message realizes positioning.

Optionally, the CDMA signal includes a CDMA pilot frequency and a CDMA navigation signal carrying a navigation message, and the OFDM signal includes an OFDM symbol for carrying communication services and an OFDM ranging signal. The generation module 72 is specifically used to convert the CDMA pilot frequency and OFDM measurement The distance signal is carried in the beacon part, and the OFDM symbol and the CDMA navigation signal used to carry the communication service are carried in the data carrying part to generate a positioning message.

Optionally, the generating module 71 is specifically configured to carry the OFDM symbol used by the data bearing part to carry communication services and the CDMA navigation signal on the data bearing part at the same time and at the same frequency.

Optionally, the generating module 71 is specifically configured to adjust the strength of the CDMA navigation signal according to the signal strength of the OFDM symbol used to carry the communication service.

The positioning message transmission device in the embodiment of the present invention can implement the above method embodiment. The components of the device and the functions of each module are only briefly described. For detailed description, please refer to the above method embodiment.

The positioning message transmission device in this embodiment generates a positioning signal carrying both the CDMA signal and the OFDM signal by coupling the CDMA signal and the OFDM signal used for positioning, and transmits the positioning signal to the positioning terminal, so that the positioning signal realizes positioning. In this way, the positioning signal carries the CDMA signal and the OFDM signal at the same time, which can improve the signal quality, so that the positioning terminal can use the CDMA signal and the OFDM signal for positioning, thereby improving the positioning accuracy.

Example 6

As shown in FIG. 8 , this embodiment provides a code division multiple access and orthogonal frequency division multiple access signal coupling ranging system, including an upstream device 81 and a ranging device 82, wherein:

The upstream device 81 is used to couple the CDMA signal used for positioning and the OFDM signal used for positioning to generate a positioning signal that simultaneously carries the CDMA signal and the OFDM signal; transmit the positioning signal to the distance measuring device; the upstream device can execute the embodiment method in 4. That is, the upstream device may refer to the positioning message transmission device shown in Embodiment 5.

The distance measuring device 82 is the distance measuring device of the third embodiment described above.

The ranging system of the embodiment of the present invention receives the positioning signal sent by the upstream device and carries the CDMA signal for positioning and the OFDM signal for positioning; analyzes the positioning signal to obtain the CDMA signal; analyzes the positioning signal to obtain the OFDM signal; according to the CDMA signal and OFDM signal for ranging. In this way, by receiving the positioning signal carrying the CDMA signal for positioning and the OFDM signal for positioning at the same time, the CDMA signal and the OFDM signal are used for ranging at the same time, so that the ranging error can be reduced and the positioning accuracy can be improved.

In the embodiment of the present invention, the influence of multipath on CDMA signal and OFDM signal is shown in Figure 9. As far as CDMA signal is concerned, the smaller the correlator spacing d is, the smaller the error generated by multipath is. When the multipath delay is greater than When (1+d) chips, the CDMA code phase measurement error caused by multipath is 0. However, when the correlator spacing d is too small, the phase operating points of the leading and lagging correlators will be near the top of the main peak of the autocorrelation function. In reality, due to bandwidth limitations, the curve of the correlation function is not an ideal triangle, and it is relatively smooth near the top of the main peak of the function. Therefore, too small a distance between correlators will reduce the sensitivity and dynamics of the code loop. However, for OFDM signals, the ranging error fluctuates periodically with the multipath time delay. When the multipath delay is small, CDMA ranging is more seriously affected by multipath. When the multipath delay is large, CDMA ranging is no longer affected by multipath, but multipath interference still exists in OFDM ranging.

The ranging method, device, and system for coupling CDMA and OFDM signals in the embodiments of the present invention make full use of the complementary ranging characteristics of CDMA and OFDM signals in multipath channels, and alleviate the multiple distance measurement error. At the same time, the TC-OFDM signal system proposed by this technology can realize high-precision ranging and navigation without affecting OFDM services.

Those of ordinary skill in the art can understand that all or part of the steps for implementing the above embodiments can be completed by hardware, and can also be completed by instructing related hardware through a program. The program can be stored in a computer-readable storage medium. The above-mentioned The storage medium mentioned may be a read-only memory, a magnetic disk or an optical disk, and the like.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for relevant parts, please refer to part of the description of the method embodiment. The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without creative effort.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

If the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes. .

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be realized by means of software plus necessary general-purpose hardware. The general-purpose hardware includes general-purpose integrated circuits, general-purpose CPUs, general-purpose memories, general-purpose components, etc. , Of course, it can also be realized by dedicated hardware including application-specific integrated circuits, dedicated CPUs, dedicated memories, dedicated components, etc., but in many cases the former is a better implementation. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a readable storage medium, such as a floppy disk of a computer , a hard disk or an optical disk, etc., including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute the methods of various embodiments of the present invention.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention Inside.

Claims (9)

1. A method for measuring distance by coupling code division multiple access and orthogonal frequency division multiple access signals is characterized by comprising the following steps:

receiving a positioning signal sent by upstream equipment, wherein the positioning signal simultaneously carries a Code Division Multiple Access (CDMA) signal for positioning and an orthogonal frequency division multiple access (OFDM) signal for positioning, and the upstream equipment couples the CDMA signal and the OFDM signal to obtain the positioning signal;

analyzing the positioning signal to obtain the CDMA signal;

analyzing the positioning signal to obtain the OFDM signal;

performing ranging according to the CDMA signal and the OFDM signal;

performing ranging according to the CDMA signal and the OFDM signal includes:

the CDMA signal is used for capturing the first path and the multipath outside the chip, and the CDMA signal is used for tracking the first path and the multipath outside the chip to reproduce the first path and the multipath outside the chip;

calculating a multipath error correction term according to a multipath signal reproduction result;

according to the multipath error correction term, correcting a frequency domain code sequence obtained by FFT of a received signal;

performing pseudo-range calculation based on the corrected received signal;

calculating a multipath error correction term according to a multipath signal reproduction result includes: according to the multipath signal reproduction result, the following formula is applied to calculate the multipath error correction term,

${\mathrm{\Δ}}_i=\underset{p=1}{\overset{q}{\mathrm{\Σ}}}{A}_p{d}_i\exp \[-j2\mathrm{\π}i({\mathrm{\τ}}_p-{\mathrm{\τ}}_0)/T\];$

wherein q is the number of off-chip multipaths obtained by CDMA tracking, d_iRepresenting a code adopted by an ith subcarrier of the OFDM signal; j represents an imaginary part; t is the time length of the OFDM ranging coincidence; tau'₀Is the difference between the actual time delay of the first path signal and τ 0, A_pIs the amplitude of the p-th path signal; tau is_pDelay time of the p path signal;

according to the multipath error correction term, correcting the frequency domain code sequence obtained by FFT of the received signal comprises the following steps: according to the multipath error correction term, the frequency domain code sequence obtained by FFT of the received signal is corrected by applying the following formula,

Z_i＝Y_i(X_i-Δ_i)^*；

wherein,is a complex sequence X_iConjugation of (1); y is_iIs a frequency domain code sequence on each subcarrier.

2. The method of claim 1, wherein said resolving the positioning signal to obtain the CDMA signal comprises:

determining an initial code phase and a carrier frequency of the CDMA signal;

and obtaining the transmission delay of the CDMA signal according to the initial code phase and the carrier frequency of the CDMA signal.

3. The method of claim 1, wherein after obtaining the CDMA signal transmission delay according to the initial code phase and carrier frequency of the CDMA signal, further comprising:

and tracking the CDMA signal according to the initial code phase and the carrier frequency of the CDMA signal to obtain time and frequency synchronization information, and demodulating a navigation message.

4. The method of claim 3, wherein parsing the positioning signal to obtain the OFDM signal comprises:

determining the time slot of the OFDM signal according to the navigation message;

and performing time delay measurement on the time slot of the OFDM signal according to the time and frequency synchronization information to obtain the transmission time delay of the OFDM signal.

5. A cdma and ofdma signal coupling ranging apparatus, comprising:

a receiving module, configured to receive a positioning signal sent by an upstream device, where the positioning signal simultaneously carries a CDMA signal for positioning and an OFDM signal for positioning, and the positioning signal is obtained by coupling the CDMA signal and the OFDM signal with the upstream device;

the first analysis module is used for analyzing the positioning signal to obtain the CDMA signal;

the second analysis module is used for analyzing the positioning signal to obtain the OFDM signal;

the ranging module is used for ranging according to the CDMA signal and the OFDM signal;

the distance measurement module is used for capturing the first path and the multipath outside the chip by using the CDMA signal, tracking the first path and the multipath outside the chip by using the CDMA signal and reproducing the first path and the multipath outside the chip; calculating a multipath error correction term according to a multipath signal reproduction result; according to the multipath error correction term, correcting a frequency domain code sequence obtained by FFT of a received signal; performing pseudo-range calculation based on the corrected received signal;

the ranging module applies the following formula to calculate a multipath error correction term,

${\mathrm{\Δ}}_i=\underset{p=1}{\overset{q}{\mathrm{\Σ}}}{A}_p{d}_i\exp \[-j2\mathrm{\π}i({\mathrm{\τ}}_p-{\mathrm{\τ}}_0)/T\];$

wherein q is the number of off-chip multipaths obtained by CDMA tracking, d_iRepresenting a code adopted by an ith subcarrier of the OFDM signal; j represents an imaginary part; t is the time length of the OFDM ranging coincidence; tau'₀Is the difference between the actual time delay of the first path signal and τ 0, A_pIs the amplitude of the p-th path signal; tau is_pDelay time of the p path signal;

the ranging module is used for correcting the frequency domain code sequence obtained by FFT of the received signal according to the multipath error correction term by applying the following formula,

Z_i＝Y_i(X_i-Δ_i)^*；

wherein,is a complex sequence X_iConjugation of (1); y is_iIs a frequency domain code sequence on each subcarrier.

6. The apparatus of claim 5, wherein the first parsing module is specifically configured to determine an initial code phase and a carrier frequency of the CDMA signal; and obtaining the transmission delay of the CDMA signal according to the initial code phase and the carrier frequency of the CDMA signal.

7. The apparatus of claim 5, wherein the first parsing module is further configured to track the CDMA signal according to an initial code phase and a carrier frequency of the CDMA signal, obtain time and frequency synchronization information, and demodulate a navigation message.

8. The apparatus according to claim 7, wherein the second parsing module is specifically configured to determine a time slot in which the OFDM signal is located according to the navigation message; and performing time delay measurement on the time slot of the OFDM signal according to the time and frequency synchronization information to obtain the transmission time delay of the OFDM signal.

9. A code division multiple access and orthogonal frequency division multiple access signal coupling ranging system is characterized by comprising upstream equipment and a ranging device, wherein:

the upstream device is used for coupling a CDMA signal for positioning and an OFDM signal for positioning to generate a positioning signal for simultaneously carrying the CDMA signal and the OFDM signal; transmitting the positioning signal to the ranging device;

the distance measuring device as claimed in any one of the preceding claims 5-8.