CN113691477B

CN113691477B - Carrier phase tracking method and device

Info

Publication number: CN113691477B
Application number: CN202010426689.XA
Authority: CN
Inventors: 郑占旗; 达人; 任斌; 于大飞; 李刚; 方荣一; 张振宇; 孙韶辉
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2022-10-18
Anticipated expiration: 2040-05-19
Also published as: CN113691477A

Abstract

The invention provides a carrier phase tracking method and a device thereof, which are applied to a simulated receiving end in an Orthogonal Frequency Division Multiplexing (OFDM) symbol transmission simulation system, wherein the OFDM symbol transmission simulation system comprises a simulated sending end and the receiving end, and the method comprises the following steps: receiving an OFDM symbol which is sent by a sending end and subjected to integral multiple transmission delay adjustment; carrying out carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a Positioning Reference Signal (PRS); determining phase step quantity between adjacent subcarriers according to the obtained tracking phase; and determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS, and positioning the receiving end according to the tracking phase of the central carrier. The scheme provided by the invention solves the problem that the existing method for simulating carrier phase tracking of the OFDM symbol transmission simulation system has transmission delay modeling error and cannot meet the high-precision positioning requirement of a 5G NR system.

Description

Carrier phase tracking method and device

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a carrier phase tracking method and device.

Background

The 3GPP TS 22.862[1] standard defines that a next Generation 3GPP (3 rd Generation Partnership Project) wireless communication system supports a positioning accuracy of less than 3 meters in 80% of application scenarios. Meanwhile, the 3GPP TS 22.261 2 standard also defines that the 3GPP wireless communication system should support the high-precision positioning requirement of 0.5 meter in some application scenes. According to the current evaluation result, the positioning error range of the existing positioning method based on wireless communication network signals is from tens of meters to tens of meters or more, and the positioning accuracy requirement of the next generation of 3GPP wireless communication system is difficult to achieve.

The GNSS (Global navigation satellite system) carrier phase positioning technology is a high-precision positioning technology. In GNSS carrier-phase positioning, a GNSS receiver, such as a user terminal, accurately determines its position by measuring carrier-phase measurements obtained from GNSS satellite signals.

At present, when a GNSS carrier phase positioning system is constructed to perform carrier phase positioning, a simulation system model of an OFDM signal is generally used first to perform positioning system modeling according to a GNSS carrier phase positioning scene, so as to verify the feasibility of constructing the GNSS carrier phase positioning system, and provide guidance and theoretical support for construction of the GNSS carrier phase positioning system. Currently, when a simulation system model of an OFDM signal is used to perform simulation modeling of a GNSS carrier phase positioning system, the simulation modeling includes a process of receiving and transmitting a positioning reference signal between a simulation network side device and a user terminal, and a process of the user terminal performing carrier phase tracking according to the received positioning reference signal and determining position information of the user terminal according to the tracked carrier phase, where the positioning reference signal is carried by an OFDM symbol.

The existing OFDM symbol transmission simulation system for modeling a carrier phase positioning system is realized by integral multiple Ts (radio frequency sampling interval) time delay cyclic shift of a baseband signal when modeling transmission time delay and carrier phase tracking are carried out, phase rotation of a carrier on corresponding time delay is not modeled, and the decimal time Ts time delay of the baseband signal is not really modeled in an OFDM signal model of a sending end. Therefore, in the current method for simulating carrier phase tracking by an OFDM symbol transmission simulation system, a transmission delay modeling error exists, which causes an error between a signal received by a receiving end and a phase generated by a real delay, and the high-precision positioning requirement of a 5G NR system cannot be met.

Disclosure of Invention

The invention provides a carrier phase tracking method and equipment, which are used for solving the problem that the existing method for simulating carrier phase tracking of an OFDM symbol transmission simulation system has transmission delay modeling error and cannot meet the high-precision positioning requirement of a 5G NR system.

According to a first aspect of the embodiments of the present invention, there is provided a carrier phase tracking method, applied to a simulated receiving end in an orthogonal frequency division multiplexing OFDM symbol transmission analog system, where the OFDM symbol transmission analog system includes a simulated transmitting end and the receiving end, the method including:

receiving the OFDM symbols which are sent by the sending end and subjected to integral multiple transmission delay adjustment;

carrying out carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a Positioning Reference Signal (PRS);

determining a phase step quantity between adjacent subcarriers according to the obtained tracking phase;

and determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS, so as to position the receiving end according to the tracking phase of the central carrier.

Optionally, the determining a phase step amount between adjacent subcarriers according to the obtained tracking phase includes:

and carrying out differential operation on tracking phases of adjacent subcarriers in the subcarriers carrying the PRS, and averaging the obtained differential operation results to obtain the phase step quantity between the adjacent subcarriers.

Optionally, the determining a tracking phase of a central carrier according to the phase step quantity and a tracking phase of a subcarrier carrying the PRS includes:

fitting the tracking phase of the subcarrier carrying the PRS to a curve with the same slope by curve fitting according to the phase step quantity and the tracking phase of the subcarrier carrying the PRS;

and determining the tracking phase of the central carrier according to the tracking phase of the corresponding sub-carrier bearing the PRS on the curve and the phase step quantity.

Optionally, the determining, according to the tracking phase of the subcarrier carrying the PRS corresponding to the curve and the phase step amount, the tracking phase of the central carrier includes:

computing

Wherein,

the tracking phase for the center carrier wave,

for the tracking phase of the K-th sub-carrier among the sub-carriers carrying PRS on the curve,

and K is an integer and is the phase step quantity.

Optionally, the receiving the OFDM symbol sent by the sending end and adjusted by the integer multiple transmission delay includes:

and receiving the scene corresponding to the OFDM symbol transmission simulation system, estimating the estimated transmission delay between the transmitting end and the receiving end, rounding the radio frequency sampling interval according to the estimated transmission delay to obtain integral multiple transmission delay, and adding the OFDM symbols transmitted after the integral multiple transmission delay.

Optionally, the receiving the OFDM symbol sent by the sending end and subjected to the integer-multiple transmission delay adjustment includes:

receiving an OFDM signal transmitted by a radio frequency carrier after the transmitting terminal carries out fast Fourier inverse transformation, equivalent up-conversion and integral multiple transmission delay adjustment on an OFDM symbol;

and carrying out equivalent down-conversion and fast Fourier transform on the OFDM signal to obtain the OFDM symbol.

Optionally, the phase tracking on the OFDM symbol includes:

and performing phase tracking on the OFDM symbols by using a carrier phase tracking algorithm based on a Phase Locking Loop (PLL).

Optionally, the performing a differential operation on tracking phases of adjacent subcarriers in the subcarriers carrying the PRS includes:

and forming tracking phases of subcarriers carrying PRS into a phase matrix, and carrying out differential operation on the phase matrix, wherein the phase matrix is a row matrix or a column matrix.

According to a second aspect of embodiments of the present invention, there is provided a carrier phase tracking apparatus including:

the signal receiving module is used for receiving the OFDM symbols which are sent by the sending end and subjected to integral multiple transmission delay adjustment;

the carrier tracking module is used for carrying out carrier phase tracking on the OFDM symbols to obtain tracking phases of subcarriers bearing Positioning Reference Signals (PRS);

the parameter calculation module is used for determining phase step quantity between adjacent subcarriers according to the obtained tracking phase;

and the carrier tracking determining module is used for determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier bearing the PRS, and positioning the receiving end according to the tracking phase of the central carrier.

Optionally, the determining, by the parameter calculation module, a phase step amount between adjacent subcarriers according to the obtained tracking phase includes:

Optionally, the determining, by the carrier tracking module, a tracking phase of a central carrier according to the phase step amount and a tracking phase of a subcarrier carrying a PRS includes:

fitting the tracking phase of the subcarrier carrying the PRS to a curve with the same slope through curve fitting according to the phase step quantity and the tracking phase of the subcarrier carrying the PRS;

Optionally, the determining, by the carrier tracking module, a tracking phase of a central carrier according to the tracking phase of the corresponding sub-carrier carrying the PRS on the curve and the phase step amount includes:

computing

Wherein,

the tracking phase for the center carrier wave,

and K is an integer and is the phase step quantity.

Optionally, the receiving, by the signal receiving module, the OFDM symbol sent by the sending end and adjusted by integer multiple transmission delay includes:

Optionally, the receiving, by the signal receiving module, the OFDM symbol sent by the sending end and subjected to the adjustment of the integer multiple transmission delay includes:

receiving an OFDM signal transmitted by a radio frequency carrier after the OFDM symbol is subjected to fast Fourier inverse transformation, equivalent up-conversion and integral multiple transmission delay adjustment by the transmitting end;

Optionally, the phase tracking performed on the OFDM symbol by the carrier tracking module includes:

Optionally, the performing, by the parameter calculation module, a difference operation on tracking phases of adjacent subcarriers in the subcarriers carrying the PRS includes:

According to a third aspect of embodiments of the present invention, there is provided a carrier phase tracking apparatus including: a memory and a processor; wherein:

the memory is used for storing a computer program;

the processor is used for reading the program in the memory and executing:

and determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier bearing the PRS, and positioning the receiving end according to the tracking phase of the central carrier.

Optionally, the processor determines a phase step amount between adjacent subcarriers according to the obtained tracking phase, including:

Optionally, the determining, by the processor, the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS includes:

Optionally, the determining, by the processor, the tracking phase of the central carrier according to the tracking phase of the corresponding sub-carrier carrying the PRS on the curve and the phase step amount includes:

computing

Wherein,

the tracking phase for the center carrier wave,

for the tracking phase of the K-th subcarrier among the subcarriers carrying PRS on the curve,

and K is an integer as the phase step quantity.

Optionally, the receiving, by the processor, the OFDM symbol after performing integer-multiple transmission delay adjustment sent by the sending end includes:

and receiving the OFDM symbols which are sent by the sending end after the integral multiple transmission delay is added, wherein the sending end estimates the estimated transmission delay between the sending end and the receiving end according to the scene corresponding to the OFDM symbol transmission simulation system, the integral multiple transmission delay is obtained by rounding the radio frequency sampling interval according to the estimated transmission delay.

Optionally, the processor performs phase tracking on the OFDM symbol, including:

and carrying out phase tracking on the OFDM symbols by utilizing a carrier phase tracking algorithm based on a phase-locked loop (PLL).

Optionally, the processor performs a differential operation on tracking phases of adjacent subcarriers in the subcarriers carrying the PRS, including:

According to a fourth aspect of the embodiments of the present invention, there is provided a chip, which is coupled to a memory in a device, so that when the chip calls a program instruction stored in the memory during running, the chip implements the above aspects of the embodiments of the present application and any method that may be involved in the aspects.

According to a fifth aspect of embodiments of the present invention, there is provided a computer-readable storage medium storing program instructions that, when executed on a computer, cause the computer to perform the various aspects of embodiments of the present invention described above and any methods to which the various aspects relate.

According to a sixth aspect of embodiments of the present invention, there is provided a computer program product, which, when run on an electronic device, causes the electronic device to perform a method of implementing the various aspects of embodiments of the present application and any possible references to the various aspects.

The carrier phase tracking method and the carrier phase tracking device provided by the invention have the following beneficial effects:

the invention provides a carrier phase tracking method and equipment, which are applied to a receiving end in an Orthogonal Frequency Division Multiplexing (OFDM) symbol transmission simulation system, wherein the receiving end tracks the carrier phase of a received OFDM symbol, and then determines the phase step quantity between adjacent subcarriers according to the characteristic that the carrier phase corresponding to decimal time delay has step, so that the tracking phase of a central carrier can be determined, and the delay modeling process does not have the error caused by the fact that a sending end does not model decimal transmission delay in the tracking phases of other subcarriers in the OFDM symbol, so that the receiving end can be accurately positioned based on the accurate carrier tracking phase, and the problems that the transmission delay modeling error exists in the method for simulating carrier phase tracking of the existing OFDM symbol transmission simulation system, and the high-precision positioning requirement of a 5G NR system cannot be met are solved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of an OFDM symbol transmission analog system applied to a carrier phase tracking method according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a carrier phase tracking method according to an embodiment of the present invention;

fig. 3 is a schematic signal transmission diagram of an OFDM symbol transmission analog system according to an embodiment of the present invention;

fig. 4 is a schematic diagram of an analysis of carrier tracking phase in a current OFDM symbol transmission analog system according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a structure of a carrier phase tracking loop based on a PLL according to an embodiment of the present invention;

fig. 6 is a schematic diagram illustrating a frequency domain phase change of an OFDM symbol in a subframe when an integral multiple delay is unchanged according to an embodiment of the present invention;

fig. 7 is a schematic diagram illustrating a frequency domain phase change situation of an OFDM symbol in a subframe when an integer multiple of delay changes according to an embodiment of the present invention;

fig. 8 is a schematic diagram of a carrier phase tracking device provided in an embodiment of the present invention;

fig. 9 is a schematic structural diagram of a carrier phase tracking device provided in an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the embodiment of the present application, "and/or" describes an association relationship of associated objects, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

For convenience of understanding, terms referred to in the embodiments of the present invention are explained below:

1) OFDM (Orthogonal Frequency Division Multiplexing): the parallel transmission of high-speed serial data is realized through frequency division multiplexing, the multi-path fading resistance is good, and multi-user access can be supported; the main idea of OFDM is to divide the channel into several orthogonal sub-channels, convert the high speed data signal into parallel low speed data flow, modulate to each sub-channel and transmit by sub-carrier, each sub-carrier is orthogonal, therefore the frequency spectrum after spread spectrum modulation can overlap each other, not only reduce the mutual interference among sub-carriers, but also can improve the frequency spectrum utilization;

2) PLL (Phase Lock Loop): PLL is a feedback control circuit, which keeps tracking the phase of the input signal by measuring the phase difference between the local carrier and the input carrier, and can realize automatic tracking of the frequency of the output signal to the frequency of the input signal, and is usually used in a closed-loop tracking circuit; a phase-locked loop is generally composed of three parts, a phase detector, a loop filter and a voltage-controlled oscillator.

In high-precision positioning research based on 5G carrier phase tracking, an OFDM symbol transmission simulation system is generally used to perform system modeling on a carrier phase positioning scene, verify the implementability of a related positioning algorithm, perform related adjustment improvement and the like, and further construct a 5G high-precision carrier phase positioning system. When the transceiving process of the positioning reference signal between the network side equipment and the user terminal is simulated, because transmission delay exists in signal transmission between the network side equipment and the user terminal in an actual positioning scene, the transceiving of the signal in the OFDM symbol transmission simulation system also needs to model the transmission delay in the positioning scene, and the transmission delay is added to the signal transmission process so as to ensure the consistency with the actual positioning scene.

At present, when modeling is carried out on transmission delay, the modeling is realized by time delay cyclic shift of integral multiple Ts (radio frequency sampling interval) of baseband signals, and the time delay of a small multiple in the transmission delay cannot be added in the signal transmission process due to the limitation of discrete time intervals of a digital communication system. In the existing OFDM symbol transmission simulation system, only integral multiple time delay is added in a baseband signal received by a receiving end and sent by a sending end, so that decimal transmission time delay errors exist between the phase generated by the signal of the receiving end and the real time delay, the positioning precision is reduced, and the high-precision positioning requirement cannot be met.

In view of this, the embodiment of the present invention provides a carrier phase tracking method, which is applied to a receiving end simulated in an orthogonal frequency division multiplexing OFDM symbol transmission simulation system, and is specifically applied to a simulation of a 5G high-precision carrier phase positioning scene by the OFDM symbol transmission simulation system. The OFDM symbol transmission simulation system comprises a simulated transmitting end and the receiving end.

Referring to fig. 1, a schematic diagram of an OFDM symbol transmission analog system applied to a carrier phase tracking method according to an embodiment of the present invention is shown. As shown in the figure, the OFDM symbol transmission analog system provided in the embodiment of the present invention includes a transmitting end 101 and a receiving end 102.

The receiving end 102 is configured to receive the OFDM symbol sent by the sending end 101 and subjected to integer-multiple transmission delay adjustment; carrying out carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a Positioning Reference Signal (PRS); determining phase step quantity between adjacent subcarriers according to the obtained tracking phase; and determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS, so as to position the receiving end according to the tracking phase of the central carrier.

The transmitting end 101 is configured to estimate an estimated transmission delay between the transmitting end and the receiving end according to a scene corresponding to the OFDM symbol transmission simulation system; rounding the estimated transmission delay to the radio frequency sampling interval to obtain integral multiple transmission delay; adding an integral multiple of transmission delay to the OFDM symbol, and sending the OFDM symbol to the receiving end 102.

In the embodiment of the present invention, the simulated receiving end is a user terminal device in a simulated actual positioning scene, and the user terminal device may specifically refer to an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user equipment. An access terminal may be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with Wireless communication capability, a computing device or other processing device connected to a Wireless modem, a vehicle mounted device, a wearable device, a Mobile station in a 5G NetworK, or a subscribing device in a future evolved Public Land Mobile NetworK (PLMN) NetworK, etc. The receiving end can implement the same function as the simulated user terminal device.

In this embodiment of the present invention, the simulated transmitting end is a network side device in a simulated actual positioning scene, and the network side device may be a next generation Base Station (gNB) in a 5G System, and may be a Base Transceiver Station (BTS) in a Global System of Mobile communication (GSM) System or a Code Division Multiple Access (CDMA) System, or may be a Base Station (NodeB, NB) in a Wideband Code Division Multiple Access (WCDMA) System, or may be an evolved Node B (eNB or eNodeB) in a Long Term Evolution (LTE) System, or the like. The sending end can realize the same functions as the simulated network side equipment.

For convenience of description, only one simulated transmitting end and one simulated receiving end are illustrated in fig. 1, and in an actual simulation system, multiple simulated transmitting ends and multiple simulated receiving ends may coexist, which is not described herein again. It should be noted that the above-mentioned system architecture is only an example of the system architecture applicable to the embodiment of the present invention, and the system architecture applicable to the embodiment of the present invention may further add other simulated entities or reduce part of the simulated entities compared with the system architecture shown in fig. 1.

Example 1

The embodiment of the invention provides a carrier phase tracking method which is applied to an Orthogonal Frequency Division Multiplexing (OFDM) symbol transmission simulation system. The OFDM symbol transmission simulation system includes a simulated transmitting end and a simulated receiving end, as shown in fig. 2, the method includes:

step S201, a receiving end receives an OFDM symbol which is sent by the sending end and is subjected to integral multiple transmission delay adjustment;

referring to fig. 3, a signal transmission diagram of an OFDM symbol transmission analog system according to an embodiment of the present invention is shown.

In the OFDM symbol transmission simulation system provided by the embodiment of the present invention, a transmitting end estimates an estimated transmission delay between the transmitting end and a receiving end according to a scene corresponding to the OFDM symbol transmission simulation system; rounding the estimated transmission delay to the radio frequency sampling interval to obtain integral multiple transmission delay; and adding integral multiple transmission time delay to the OFDM symbol and then sending the OFDM symbol to the receiving end.

As shown in fig. 3, after the transmitting end performs inverse fast fourier transform, equivalent up-conversion, and integer-times transmission delay adjustment on the OFDM symbol, the adjusted OFDM signal is transmitted by using a radio frequency carrier.

Specifically, when a sending end sends a positioning reference signal, a PRS sequence used for carrier phase tracking is generated, the frequency domain mode type of the sequence is a Gold sequence, and the sequence is transmitted by using an OFDM symbol with N subcarriers, wherein the subcarrier interval in the OFDM symbol is delta f _scs With a sampling time interval of T _s ＝1/(NΔf _scs )。

OFDM transmission is based on a block OFDM model, i.e. the channel within each OFDM symbol remains unchanged. A composite signal comprising a plurality of modulated subcarriers within each OFDM symbol, wherein each subcarrier may be modulated by phase shift keying, PSK, or quadrature amplitude modulation, QAM. In this embodiment, it is assumed that each subcarrier is QAM modulated, and that the obtained N QAM modulation symbols are assumed

K ∈ {0,1, \8230;, N-1} is grouped into a vector

Transmitted in the mth OFDM symbol of the transmission slot. To pair

Performing normalized inverse discrete time Fourier transform (IDFT), and transforming the spectrum expression into time domain to obtain the time duration of T = NT _s ＝1/Δf _scs The continuous-time representation of the complex envelope of the OFDM symbol of (1), as shown in the following equation:

wherein,

frequency domain of the Kth subcarrier signal of the mth OFDM symbolDenotes x ^m (T) is the time domain representation of the complex envelope of the mth OFDM symbol, T is the duration of the OFDM symbol, N is the number of subcarriers in the OFDM symbol, i.e., the length of the OFDM symbol, and m and N are integers.

For x ^m (T) by sampling the time interval T _s Sampling discrete time signal in digital baseband

N ∈ {0,1, \8230;, N-1} may be expressed as:

wherein,

t in digital baseband obtained for complex envelope sampling of mth OFDM symbol _n Discrete time signal of time of day.

The time domain signal x ^m (t) is up-converted to a center frequency f _c The resulting radio frequency signal is represented as:

wherein T is more than or equal to 0 and less than or equal to T, T is the duration of the OFDM symbol,

frequency domain representation of the Kth subcarrier signal for the mth OFDM symbol, x ^m (t) is a time domain representation of the complex envelope of the mth OFDM symbol.

And the transmitting end adds an integral multiple transmission time delay to the signal obtained after the up-conversion and transmits the signal to the receiving end through a radio frequency carrier. As shown in fig. 3, before performing up-conversion on the OFDM symbols, the transmitting end may add a cyclic prefix CP to the OFDM symbols to protect them. For the above OFDM symbol, N subcarriers are included, and the subcarrier spacing is Δ f _scs Given the length of the cyclic prefixDegree of N _cp Then N will be _cp ＝N+N _cp Expressed as the length of one OFDM symbol. In actual scenes, time delay caused by a transmission path, deviation of sampling clocks and crystal oscillator frequencies at the transmitting end and the receiving end and process noise introduced in the transmission process exist, and phase, frequency and sampling time offset exists in a signal reaching a receiving end compared with a signal sent by a sending end, and the phase, frequency and sampling time offset are respectively used

And delta f and delta t indicate that the transmitting end estimates the offset and adds the offset to the determined signal to be transmitted, and the receiving end receives the signal containing the three offsets transmitted by the transmitting end and performs Fast Fourier Transform (FFT) to obtain received frequency domain data:

wherein,

for the frequency domain representation of the received signal at the receiving end, δ f = Δ f/f _scs For normalized frequency offset after normalization with subcarrier spacing, l represents the l-th OFDM symbol, K represents the K-th subcarrier in the OFDM symbol,

in order to be a channel impulse response,

for complex field data carried on the kth subcarrier of the ith OFDM symbol,

for noisy data including noise and intercarrier interference, l and K are integers.

In the embodiment of the invention, the sending end adds transmission time delay to the sent OFDM symbol, and the OFDM symbol is realized by circularly shifting a baseband based on integral multiple sample pointsIn the method, a transmitting end estimates estimated transmission delay emission between the transmitting end and a receiving end according to an actual scene corresponding to an OFDM symbol transmission simulation system, and a frequency carrier is integrally added to all carriers based on the estimated transmission delay, so that the addition of the transmission delay delta tau (t) comprises two parts, namely, firstly, the delay delta tau (t) is added to the central frequency f of the radio frequency carrier _c I.e. adding a common phase rotation of-2 pi f to the time domain signal _c Δ τ (t), and then cyclic shift is performed at the baseband, the number of shift points being floor (Δ τ (t)) = N _τ Where floor denotes the rounding of Δ τ (t), N _τ Denotes an integer rounded to Δ τ (t).

In the embodiment of the present invention, the method for adding an integer multiple of transmission delay to the transmitted OFDM symbol by the sending end may be the same as that in the prior art, and details are not described here.

In the embodiment of the invention, the sending end carries out integral multiple time delay adjustment on the OFDM symbols according to the method and then sends the OFDM symbols to the receiving end, and the receiving end receives the OFDM symbols and carries out carrier phase tracking. As shown in fig. 3, the receiving end receives an OFDM signal transmitted by the transmitting end through a radio frequency carrier after performing inverse fast fourier transform, equivalent up-conversion, and integer-times transmission delay adjustment on an OFDM symbol; and the receiving end performs equivalent down-conversion and fast Fourier transform on the OFDM signal to obtain the OFDM symbol, and performs carrier phase tracking on the OFDM symbol.

Step S202, carrying out carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a Positioning Reference Signal (PRS);

the integral multiple time delay added by the sending end according to the delta tau (t) in the steps can be expressed as N _τ *T _s When the unadditized fractional time delay is represented by Δ τ' (t), Δ τ (t) = N _τ *T _s + Δ τ' (t). Adding integral multiple time delay to a sending end, wherein the theoretical phase added to the Kth subcarrier in the OFDM symbol is as follows:

-2πf _c Δτ(t)-2πKf _scs *N _τ *T _s

referring to fig. 4, an exemplary embodiment of the present invention provides an analog system for current OFDM symbol transmissionThe analysis of the carrier tracking phase in the system is shown schematically. On the basis that the phase of all subcarriers is tracked by PLL, all subcarrier phase curves in OFDM symbols are shown as a straight line L1 in the figure, all subcarrier phase curves in real error-free OFDM symbols are shown as a straight line L2 in the figure, both curves comprise a negative frequency on the left half side and a positive frequency on the right half side, wherein a parallel line segment perpendicular to a frequency f axis represents one used subcarrier, and a phase modeling error of-2 pi Kf exists between the two straight lines L1 and L2 and is changed along with a subcarrier serial number K _scs * Δ τ' (t), i.e., a fractional transmission delay error.

Curves L1 and L2 shown in fig. 4 are results obtained by theoretically analyzing and determining carrier tracking results, and in the modeling process provided by the embodiment of the present invention, the curves L1 and L2 are obtained by performing curve fitting according to the tracking phase of the subcarrier in the tracked OFDM symbol.

The above process adds only an integer multiple of the delay and not a fractional multiple of the delay, thus creating a modeling error for each sub-carrier phase, which can be represented as-2 π Kf as shown in FIG. 4 _scs * Δ τ' (t), the presence of this error results in the receiver not achieving the best positioning accuracy.

As shown in fig. 4, the change of the modeled frequency domain phase and the real frequency domain phase is reflected on the difference of the slope of the curve, the slope of the curve L1 is the modeled time delay, the slope of the curve L2 is the real time delay, the time delay is different, the slope is different, but the error-free curve L2 and the error-containing curve L1 both pass through the exact f _c Phase point, hence baseband modeling error, does not affect f _c Phase, as long as the receiving end can accurately output f _c The phase of the time delay line can eliminate the influence caused by the modeling error of the baseband time delay.

By error-2 π Kf _scs * Δ τ' (t) is obtained, the transmission delay modeling error is related to the subcarrier serial number K, the smaller the modeling error, and when K =0, the modeling error is zero, and the carrier phase determined by the receiving end is the accurate carrier phase. However, in the positioning reference signal PRS sequence transmitted by the transmitting end, normally, no carrier with K =0 exists, and thus the receiving end cannot directly receive the positioning reference signal PRS sequenceTracking phase of a center carrier in the OFDM symbol. At present, the phase tracking algorithm at the receiving end can only output the used subcarrier phases, and the phases have modeling errors. Therefore, an error exists in the tracking phase output by the tracked carrier phase and related to the carrier number K, and the error increases with the increase of the carrier number K.

In the embodiment of the invention, the receiving end tracks the phases of all subcarriers in the OFDM symbol sent by the sending end, then the tracking phase of the central carrier in the OFDM symbol without modeling error is determined through frequency domain fitting, and positioning is carried out according to the tracking phase of the central carrier, so that the error caused by the transmission delay which is multiplied by a small number and is not modeled can be avoided, and an accurate positioning result is obtained.

Specifically, after receiving an OFDM symbol sent by a sending end, the receiving end performs phase tracking on the OFDM symbol by using a carrier phase tracking algorithm based on a phase locked loop PLL to obtain tracking phases of all subcarriers carrying PRS in the OFDM symbol, and determines a tracking phase of a center carrier according to the tracking phases of the subcarriers.

Fig. 5 is a schematic structural diagram of a carrier phase tracking loop based on a PLL according to an embodiment of the present invention. As shown in the figure, the carrier phase tracking loop constructed based on the carrier phase tracking algorithm of the phase lock loop PLL comprises an inner loop phase detector PED, an inner loop slope obtaining module, an inner loop filter and an inner and outer loop numerically controlled oscillator NCO. The phase discriminator is used for discriminating the phase of the input signal, comparing the phase between the input signal and the output signal and generating a phase error to adjust the phase of the output signal. The inner loop filter is used for dynamically adjusting relevant parameters of a loop, and the inner and outer loop numerical control oscillators are used for generating controllable sine or cosine signals. The inner loop is used for performing frequency domain phase tracking on an input signal, namely a subcarrier in an OFDM symbol received by a receiving end, and the outer loop is used for performing time domain phase tracking on the input signal.

In practical implementation, the PLL-based carrier phase tracking loop can track the phase of the subcarrier in the OFDM symbol by using the prior art, and is not described in detail here.

Step S203, determining phase step quantity between adjacent subcarriers according to the obtained tracking phase;

and the receiving end carries out carrier phase tracking on the sub-carrier bearing the PRS in the received OFDM symbol according to the steps to obtain the tracking phase of the sub-carrier, then carries out differential operation on the tracking phase of the adjacent sub-carrier in the sub-carrier bearing the PRS, and averages the obtained differential operation result to obtain the phase step quantity between the adjacent sub-carriers. Specifically, tracking phases of subcarriers carrying PRSs are combined into a phase matrix, and a differential operation is performed on the phase matrix, where the phase matrix is a row matrix or a column matrix. The tracking phase values of the subcarriers carrying the PRS in the OFDM symbols may be grouped into a phase matrix in a row matrix or column matrix format according to the subcarrier sequence numbers, where each row/each column in the matrix represents a tracking phase value of one subcarrier.

And S204, determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier bearing the PRS, so as to position the receiving end according to the tracking phase of the central carrier.

After the phase step quantity between adjacent subcarriers is determined, fitting the tracking phase of the subcarrier bearing the PRS to a curve with the same slope through curve fitting according to the phase step quantity and the tracking phase of the subcarrier bearing the PRS; and determining the tracking phase of the central carrier according to the tracking phase of the corresponding sub-carrier bearing the PRS on the curve and the phase step quantity.

When the tracking phase of the central carrier is determined, the following formula is used for calculation:

wherein,

the tracking phase for the center carrier wave,

and K is an integer as the phase step quantity.

After the tracking phase of the center carrier is determined, the receiving end can be located according to the tracking phase, and the implementation can adopt the prior art, which is not described in detail here.

The signal transmission implementation of the OFDM symbol transmission analog system in the embodiment of the present invention may be implemented by using a signal transmission method of an existing OFDM signal system, and compared with the process shown in fig. 3, other steps may be added, or a part of the steps may be reduced, or a specific implementation of a part of the steps may be changed, for example, the sending end performs inverse fast fourier transform on the OFDM symbol, and may be replaced with the sending end performs inverse discrete fourier transform IDFT on the OFDM symbol, or the like.

Referring to fig. 6, a schematic diagram of a frequency domain phase change of an OFDM symbol in a subframe when an integer multiple of delay is unchanged is provided in the embodiment of the present invention. Assuming that the receiving end moves at a constant speed relative to the transmitting end and gradually moves away from the transmitting end, that is, the distance from the receiving end to the transmitting end gradually increases, the transmission delay of the signal gradually increases. As shown in the figure, the variation of the carrier phase tracked by the receiving end in a subframe is given, and the number N of points if the transmitting end performs cyclic shift in the baseband _τ Unchanged, the slope of the curve corresponding to all the subcarriers does not change, and f _c Is accurate and hops once per OFDM symbol. The carrier phases at different moments are separated gradually in a discrete mode, and the phase difference among different curves reflects the real change of the time delay of the carrier.

Referring to fig. 7, a schematic diagram of a frequency domain phase change situation of an OFDM symbol in a subframe when an integer multiple of delay changes according to an embodiment of the present invention is provided. If the time delay change exceeds one Ts during the movement of the receiving end, N is conducted _τ When the change occurs, the slope of the inner-ring phase line jumps, but the jumping curve still passes through the accurate f _c And (4) phase points.

Therefore, it can be known that, in the simulation modeling of the high-precision positioning system, the accurate delay modeling has a large influence on the phase tracking, but because in the current digital simulation system, the OFDM symbol can only perform Ts cyclic shift of an integral multiple when passing through the channel to realize the non-accurate delay modeling, a modeling error is generated on the carrier phase tracking. However, in the method provided in the embodiment of the present invention, when the receiving end performs carrier phase tracking, the tracking phase of the central carrier, which is the subcarrier number K =0, is output according to the tracking phase of the subcarrier, so that a tracking result without a transmission delay modeling error can be obtained, and an accurate carrier phase tracking effect is obtained.

In the carrier phase tracking method provided by the embodiment of the present invention, the receiving end receives the OFDM symbol after the integer-time delay adjustment is performed by the sending end, performs carrier phase tracking on the OFDM symbol, and determines the tracking phase of the central carrier according to the tracking phase of the tracked subcarrier carrying the positioning reference signal PRS, so as to position the receiving end according to the tracking phase of the central carrier. Under the condition that the phase modeling error of the OFDM symbol of the transmitting end exists, the receiving end can eliminate the decimal transmission delay modeling error and accurately obtain the carrier phase value of the received OFDM symbol. The method solves the problems that the existing method for simulating carrier phase tracking of the OFDM symbol transmission simulation system has transmission delay modeling error and can not meet the high-precision positioning requirement of the 5G NR system.

The system architecture and the service scenario described in the embodiment of the present invention are for more clearly illustrating the technical solution of the embodiment of the present invention, and do not form a limitation on the technical solution provided in the embodiment of the present invention, and it can be known by those skilled in the art that the technical solution provided in the embodiment of the present invention is also applicable to similar technical problems along with the evolution of the system architecture and the appearance of a new service scenario.

Example 2

A carrier phase tracking method according to the present invention is explained above, and an apparatus for performing the carrier phase tracking method is explained below.

Referring to fig. 8, an embodiment of the present invention provides a carrier phase tracking apparatus, including:

a signal receiving module 801, configured to receive an OFDM symbol sent by the sending end and subjected to integer-multiple transmission delay adjustment;

a carrier tracking module 802, configured to perform carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a positioning reference signal PRS;

a parameter calculating module 803, configured to determine a phase step amount between adjacent subcarriers according to the obtained tracking phase;

and a carrier tracking determining module 804, configured to determine a tracking phase of a central carrier according to the phase step quantity and a tracking phase of a subcarrier carrying the PRS, and position the receiving end according to the tracking phase of the central carrier.

Optionally, the determining, by the carrier tracking module, a tracking phase of a central carrier according to the phase step quantity and a tracking phase of a subcarrier carrying the PRS includes:

computing

Wherein,

the tracking phase for the center carrier wave,

and K is an integer and is the phase step quantity.

The carrier phase tracking device provided in the embodiment of the present invention is the same as the carrier phase tracking method and device provided in the embodiment of the present invention, and various implementation manners applied to the carrier phase tracking device provided in the embodiment may be applied to the carrier phase tracking device in the embodiment for implementation, and are not repeated here.

The carrier phase tracking device in the embodiment of the present application is described above from the perspective of a modular functional entity, and the carrier phase tracking device in the embodiment of the present application is described below from the perspective of hardware processing.

Example 3

Referring to fig. 9, another embodiment of a carrier phase tracking apparatus in an embodiment of the present application includes:

a processor 900, a memory 901, a transceiver 902, and a bus interface 903.

The processor 900 is responsible for managing the bus architecture and general processing, and the memory 901 may store data used by the processor 900 in performing operations. The transceiver 902 is used to receive and transmit data under the control of the processor 900.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by processor 900, and various circuits, represented by memory 901, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The processor 900 is responsible for managing the bus architecture and general processing, and the memory 901 may store data used by the processor 900 in performing operations.

The processes disclosed in the embodiments of the present invention may be applied to the processor 900, or implemented by the processor 900. In implementation, the steps of the signal processing flow may be performed by instructions in the form of hardware, integrated logic circuits, or software in the processor 900. The processor 900 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software modules may be located in ram, flash, rom, prom, or eprom, registers, etc. as is well known in the art. The storage medium is located in the memory 901, and the processor 900 reads the information in the memory 901 and completes the steps of the signal processing flow in combination with its hardware.

Specifically, the processor 900 is configured to read a program in the memory 901 and execute:

and determining the tracking phase of a central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS, and positioning the receiving end according to the tracking phase of the central carrier.

calculating out

Wherein,

the tracking phase for the center carrier wave,

and K is an integer as the phase step quantity.

The carrier phase tracking device provided in the embodiment of the present invention is the same as the carrier phase tracking method and device provided in the embodiment of the present invention, and is applied to various implementation manners of the carrier phase tracking device provided in the embodiment, and may be applied to the carrier phase tracking device in the embodiment for implementation, and the details are not repeated here.

Embodiments of the present invention further provide a computer-readable storage medium, which includes instructions that, when executed on a computer, cause the computer to perform the carrier phase tracking method provided in the foregoing embodiments.

It can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working processes of the above-described apparatuses and modules may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical division, and in actual implementation, there may be other divisions, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed coupling or direct coupling or communication connection between each other may be through some interfaces, indirect coupling or communication connection between devices or modules, and may be in an electrical, mechanical or other form.

The modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

In addition, functional modules in the embodiments of the present application may be integrated into one processing module, or each module may exist alone physically, or two or more modules are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may be stored in a computer readable storage medium.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product.

The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device, such as a server, a data center, etc., that is integrated with one or more available media. The usable medium may be a magnetic medium (e.g., floppy disK, hard disK, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid State DisK (SSD)), among others.

The technical solutions provided by the present application are introduced in detail, and the principles and embodiments of the present application are explained by applying specific examples in the present application, and the descriptions of the above examples are only used to help understanding the method and the core ideas of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A carrier phase tracking method is applied to a simulated receiving end in an Orthogonal Frequency Division Multiplexing (OFDM) symbol transmission simulation system, wherein the OFDM symbol transmission simulation system comprises a simulated transmitting end and the receiving end, and is characterized by comprising the following steps:

determining a phase step quantity between adjacent subcarriers according to the obtained tracking phase; wherein, said determining the phase step quantity between adjacent subcarriers according to the obtained tracking phase comprises: carrying out differential operation on tracking phases of adjacent subcarriers in subcarriers bearing PRS (pseudo random access), and averaging the obtained differential operation results to obtain phase step quantity between the adjacent subcarriers;

2. The method of claim 1, wherein determining the tracking phase of the center carrier according to the phase step amount and the tracking phase of the sub-carrier carrying the PRS comprises:

3. The method of claim 2, wherein the determining the tracking phase of the center carrier according to the tracking phase of the corresponding sub-carrier carrying the PRS on the curve and the phase step amount comprises:

calculating out

Wherein,

the tracking phase for the center carrier wave,

and K is an integer as the phase step quantity.

4. The method of claim 1, wherein the receiving the OFDM symbols with integer-times transmission delay adjustment sent by the sending end comprises:

5. The method of claim 1, wherein the receiving the OFDM symbols with integer-times transmission delay adjustment sent by the sending end comprises:

6. The method of claim 1, wherein the phase tracking the OFDM symbol comprises:

7. The method of claim 1, wherein the differentiating the tracking phases of adjacent subcarriers of the subcarriers carrying the PRS comprises:

8. A carrier phase tracking device, comprising: a memory and a processor;

wherein the memory is for storing a computer program;

the processor is used for reading the program in the memory and executing:

receiving an OFDM symbol which is sent by a sending end and is subjected to integral multiple transmission delay adjustment;

determining a phase step quantity between adjacent subcarriers according to the obtained tracking phase; wherein, the processor determines the phase step quantity between adjacent subcarriers according to the obtained tracking phase, and the method comprises the following steps: carrying out differential operation on tracking phases of adjacent subcarriers in subcarriers bearing PRS (pseudo random access), and averaging the obtained differential operation results to obtain phase step quantity between the adjacent subcarriers;

and determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS, and positioning a receiving end according to the tracking phase of the central carrier.

9. The apparatus of claim 8, wherein the processor determines the tracking phase of the center carrier according to the phase step amount and the tracking phase of the sub-carrier carrying the PRS, and comprises:

10. The apparatus of claim 9, wherein the processor determines the tracking phase of the center carrier according to the tracking phase of the corresponding sub-carrier carrying the PRS on the curve and the phase step amount, and comprises:

calculating out

Wherein,

the tracking phase for the center carrier wave,

and K is an integer and is the phase step quantity.

11. The apparatus of claim 8, wherein the processor receives the OFDM symbol with integer-times transmission delay adjustment sent by a sending end, and includes:

the receiving and sending end estimates the estimated transmission time delay between the sending end and the receiving end according to the scene corresponding to the OFDM symbol transmission simulation system, obtains integral multiple transmission time delay by rounding the radio frequency sampling interval according to the estimated transmission time delay, and adds the OFDM symbols sent after the integral multiple transmission time delay.

12. The apparatus of claim 8, wherein the processor receives the OFDM symbol with integer-times transmission delay adjustment sent by a sending end, and includes:

receiving an OFDM signal which is sent by a radio frequency carrier after a sending end carries out fast Fourier inverse transformation, equivalent up-conversion and integral multiple transmission delay adjustment on an OFDM symbol;

13. The apparatus of claim 8, wherein the processor performs phase tracking on the OFDM symbol, comprising:

14. The apparatus of claim 9, wherein the processor performs a differential operation on tracking phases of adjacent ones of the PRS-bearing subcarriers, comprising:

15. A carrier phase tracking device, comprising:

a carrier tracking module, configured to perform carrier phase tracking on the OFDM symbol to obtain a tracking phase of a subcarrier carrying a positioning reference signal PRS;

the parameter calculation module is used for determining phase step quantity between adjacent subcarriers according to the obtained tracking phase; wherein, the parameter calculating module determines the phase step quantity between adjacent subcarriers according to the obtained tracking phase, and the method comprises the following steps: carrying out differential operation on tracking phases of adjacent subcarriers in subcarriers bearing PRS (pseudo random access), and averaging the obtained differential operation results to obtain phase step quantity between the adjacent subcarriers;

and the carrier tracking determination module is used for determining the tracking phase of the central carrier according to the phase step quantity and the tracking phase of the sub-carrier carrying the PRS so as to position the receiving end according to the tracking phase of the central carrier.

16. A computer program medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.