CN106789773B - Method and device for determining frequency offset and Doppler spread in high-speed mobile scene - Google Patents

Method and device for determining frequency offset and Doppler spread in high-speed mobile scene Download PDF

Info

Publication number
CN106789773B
CN106789773B CN201710058266.5A CN201710058266A CN106789773B CN 106789773 B CN106789773 B CN 106789773B CN 201710058266 A CN201710058266 A CN 201710058266A CN 106789773 B CN106789773 B CN 106789773B
Authority
CN
China
Prior art keywords
power
effective path
frequency offset
effective
representing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201710058266.5A
Other languages
Chinese (zh)
Other versions
CN106789773A (en
Inventor
许百成
邓祝明
陈建军
唐治汛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beijing Xiaomi Pinecone Electronic Co Ltd
Original Assignee
Beijing Pinecone Electronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beijing Pinecone Electronics Co Ltd filed Critical Beijing Pinecone Electronics Co Ltd
Priority to CN201710058266.5A priority Critical patent/CN106789773B/en
Publication of CN106789773A publication Critical patent/CN106789773A/en
Application granted granted Critical
Publication of CN106789773B publication Critical patent/CN106789773B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/022—Channel estimation of frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0204—Channel estimation of multiple channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0212—Channel estimation of impulse response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0222—Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention relates to a method and a device for determining frequency offset and Doppler spread in a high-speed mobile scene, wherein the method comprises the following steps: obtaining effective paths according to the channel impulse response, obtaining effective path correlation values of the effective paths, and obtaining frequency offset estimation of the effective paths according to the phases of the effective path correlation values; calculating a combining weight according to the power of each effective path, and carrying out weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation; and according to the frequency offset estimation of each effective path, weighting the average frequency offset estimation and the combining weight, obtaining the root-mean-square frequency offset expansion as the Doppler expansion estimation. The problem that the conventional method is not applicable when each direct-view path component of the multipath is large and carries different frequency offsets in a high-speed scene can be solved, and the frequency offsets can be effectively estimated; and the problems that a uniform scattering model is not established and a Bessel function is not applicable in the traditional Doppler estimation method can be solved, and the Doppler spread under a high-speed moving scene can be obtained.

Description

Method and device for determining frequency offset and Doppler spread in high-speed mobile scene
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to a method and an apparatus for determining frequency offset and doppler spread in a high-speed mobile scenario.
Background
Each multipath is composed of uniformly scattered indistinguishable paths on a conventional channel, and the frequency deviation carried by each multipath is mainly the frequency deviation between the frequency of a signal sent by a network side and the frequency of a local crystal oscillator of a terminal. At present, a private network is adopted along a high-speed rail to cover, and the network arrangement mode generally adopts a mode of combining a BBU (Base Band Unit) and an RRU (Radio Remote Unit), so that a terminal moving at a high speed among a plurality of RRUs in the same Base station can simultaneously receive wireless signals from the plurality of RRUs, and the included angles between the terminal and each RRU are different. Because each multipath of the high-speed rail channel has larger direct-view path components and fewer scattering path components, frequency offset carried by each multipath is related to factors such as the speed of the terminal, the included angle between the terminal and each RRU and the like, and the method for calculating frequency offset estimation and Doppler spread used in the prior art has the premise that each multipath in the channel carries the same frequency offset and the channel meets Rayleigh fading, so the method is not suitable for scenes involving high-speed movement any more.
Disclosure of Invention
In order to overcome the problems in the prior art, the present disclosure provides a method and an apparatus for determining frequency offset and doppler spread in a high-speed mobile scenario.
According to a first aspect of the embodiments of the present disclosure, a method for determining frequency offset and doppler spread in a high-speed moving scene is provided, including:
obtaining an effective path according to the channel impulse response;
obtaining effective path correlation values of each effective path, and obtaining frequency offset estimation of each effective path according to the phase of the effective path correlation values;
calculating a combining weight according to the power of each effective path, and performing weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation;
and obtaining root-mean-square frequency offset expansion as Doppler expansion estimation according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight.
Optionally, the obtaining the effective path according to the channel impulse response includes:
transforming the frequency domain channel estimation to a time domain to obtain a channel impulse response;
acquiring power delay distribution of each sampling point in the channel impulse response;
performing power sequencing according to the power delay distribution of each sampling point;
determining the power of noise and interference according to the power sequence and the maximum effective path number;
determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power sequence;
and taking the sampling points of which the power is greater than the power threshold in each sampling point as effective diameters.
Optionally, the obtaining the effective path correlation value of each effective path and obtaining the frequency offset estimation of each effective path according to the phase of the effective path correlation value includes:
obtaining effective diameter correlation values of each effective diameter;
and extracting the phase of the effective diameter correlation value of each effective diameter, and acquiring the frequency offset estimation of each effective diameter according to the phase extracted by the effective diameter correlation value.
Optionally, the calculating a combining weight according to the power of each effective path, and performing weighted combining on the frequency offset estimates of each effective path by using the combining weight to obtain a weighted average frequency offset estimate includes:
acquiring the power sum of the useful signal power of each effective path;
taking the ratio of the useful signal power of each effective path to the power sum of the useful signal power as the combining weight of each effective path;
and carrying out weighted combination on the frequency offset estimation of each effective path by the combining weight to obtain the weighted average frequency offset estimation.
Optionally, when the method is applied to an orthogonal frequency division multiplexing OFDM system, the transforming the frequency domain channel estimation to the time domain to obtain a channel impulse response includes:
transforming the frequency domain channel estimation to a time domain by performing Inverse Fast Fourier Transform (IFFT) on the frequency domain channel estimation to obtain the channel impulse response;
the formula of the IFFT includes:
Figure BDA0001217325830000021
wherein,
Figure BDA0001217325830000022
representation positionFrequency domain channel estimation of the ith CRS OFDM symbol in the time direction and the kth CRS RE in the frequency direction;
Figure BDA0001217325830000031
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe number of IFFT points is represented, and the total number of sampling points of the frequency domain channel estimation is equal to NFFTK denotes a total number of CRS REs in a frequency direction, and L denotes a total number of CRS symbols in a time direction;
wherein, when the IFFT is performed, N isFFTWhen the frequency domain channel estimation length is larger than K, the frequency domain channel estimation on the I CRS OFDM symbol is complemented by 0, and the length of the frequency domain channel estimation on the I CRS OFDM symbol is equal to the NFFT(ii) a When N is presentFFTWhen the frequency domain channel estimation is less than or equal to K, taking N in the frequency domain channel estimation on the l-th CRS OFDM symbolFFTThe IFFT is performed for each sample point.
Optionally, when applying to an OFDM system, the obtaining the power delay distribution of each sampling point in the channel impulse response includes:
carrying out power averaging on the channel impulse response calculated by each CRS OFDM symbol to obtain the power delay distribution PDP;
wherein the formula for performing the power averaging comprises:
Figure BDA0001217325830000032
wherein,
Figure BDA0001217325830000033
represents the power of the nth sample in the PDP,
Figure BDA0001217325830000034
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFT。
Optionally, when the method is applied to an OFDM system, the performing power sequencing according to the power delay distribution of each sampling point includes:
delaying the power sequence in the power distribution
Figure BDA0001217325830000035
Sequencing according to the sequence of the power from large to small to obtain the power sequence, wherein the power sequence comprises a new sequence
Figure BDA0001217325830000036
Wherein
Figure BDA0001217325830000037
The determining the power of the noise and the interference according to the power sequence and the maximum effective path number comprises:
according to the power sequence, the front with the maximum power in each sampling point is sequenced
Figure BDA0001217325830000038
Determining other sampling points except the individual sampling points as noise and interference sampling points;
acquiring the power of the noise and the interference according to a power calculation formula of the noise and the interference sampling points;
the calculation formula of the power of the noise and interference sampling points comprises the following steps:
Figure BDA0001217325830000041
wherein,
Figure BDA0001217325830000042
representing the number of said maximum effective diameters, NFFTThe total number of the sample points of the channel impulse response is equal to NFFT，σ2Representing the power of the noise and interference samples.
Optionally, when the method is applied to an OFDM system, the determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power rank includes:
determining the power threshold by using a power threshold calculation formula according to the power of the noise and the interference and the maximum power in the power sequence;
the power threshold calculation formula includes:
Figure BDA0001217325830000043
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing said noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure BDA0001217325830000044
representing the maximum power in the power sequence.
Optionally, when the method is applied to an OFDM system, the obtaining the effective path correlation value of each effective path includes:
calculating effective paths at the same position on adjacent CRS OFDM symbols by using a correlation value calculation formula to carry out effective path correlation values;
the correlation value calculation formula includes:
Figure BDA0001217325830000045
wherein,
Figure BDA0001217325830000046
an effective path correlation value representing the nth effective path,
Figure BDA0001217325830000047
sample i of the channel impulse response representing the i-th CRSOFDM symbol in the time directionnThe value of (a) is,
Figure BDA0001217325830000048
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sampling point of the N-th effective diameter, NpathIndicating the number of effective paths.
Optionally, when the method is applied to an OFDM system, the performing phase extraction on the effective path correlation value of each effective path, and obtaining a frequency offset estimate of each effective path according to the phase extracted from the effective path correlation value includes:
carrying out phase extraction on the effective diameter correlation values of all the effective diameters by utilizing a phase calculation formula;
obtaining the frequency offset estimation of each effective path according to the phase extracted from the correlation value of each effective path by using a frequency offset calculation formula;
wherein the phase calculation formula includes:
Figure BDA0001217325830000051
wherein,
Figure BDA0001217325830000052
the phase of the effective path correlation value representing the nth effective path,
Figure BDA0001217325830000053
effective path correlation value, N, representing the nth effective pathpathRepresenting the number of effective paths;
the frequency offset calculation formula comprises:
Figure BDA0001217325830000054
wherein,
Figure BDA0001217325830000055
and T represents the time interval of adjacent CRS OFDM symbols.
Optionally, when applied to an OFDM system, the obtaining a power sum of useful signal powers of the respective effective paths includes:
for each of the effective diameters: comparing the value obtained by subtracting the noise and interference power from the power of the effective path with zero, and taking the maximum value of the two as the useful signal power of the effective path to obtain the useful signal power of each effective path;
acquiring the power sum of the useful signal power of each effective path by using a power sum formula;
wherein the power summing formula comprises:
Figure BDA0001217325830000056
wherein,
Figure BDA0001217325830000057
represents the sum of the powers of the two or more,
Figure BDA0001217325830000058
represents the power of the nth effective path,
Figure BDA0001217325830000059
representing the useful signal power, σ, of the nth effective path2Power, N, representing the noise and interference samplespathIndicating the number of effective paths.
Optionally, when the method is applied to an OFDM system, the weighting and combining the frequency offset estimates of each effective path with the combining weight to obtain the weighted average frequency offset estimate includes:
merging the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain the weighted average frequency offset estimation;
wherein the weighted average frequency offset formula comprises:
Figure BDA0001217325830000061
wherein f isoRepresenting the weighted average frequency offset estimate, and,
Figure BDA0001217325830000062
frequency offset estimate, w, representing the nth effective pathnThe combining weights representing the frequency offset estimate for the nth effective path,
Figure BDA0001217325830000063
represents the sum of the powers of the two or more,
Figure BDA0001217325830000064
representing the useful signal power of the nth effective path.
Optionally, the obtaining, according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight, a root-mean-square frequency offset extension as a doppler extension estimation includes:
according to the frequency offset estimation of each effective diameter, the weighted average frequency offset estimation and the merging weight of each effective diameter, the root mean square frequency offset expansion is obtained by using a root mean square expansion calculation formula;
using the root mean square spread as the Doppler spread estimate;
wherein the root mean square spread calculation formula includes:
Figure BDA0001217325830000065
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure BDA0001217325830000066
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting said weighted average frequency offset estimate, NpathIndicating the number of effective paths.
According to a second aspect of the embodiments of the present disclosure, there is provided an apparatus for determining a frequency offset in a high-speed moving scene, the apparatus including:
an effective path obtaining module, configured to obtain an effective path according to the channel impulse response;
the frequency offset estimation module is used for acquiring effective path correlation values of each effective path and acquiring frequency offset estimation of each effective path according to the phase of the effective path correlation values;
the weighted average frequency offset estimation module is used for calculating a combining weight according to the power of each effective path, and carrying out weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain weighted average frequency offset estimation;
and the Doppler spread estimation module is used for acquiring root-mean-square frequency offset spread as Doppler spread estimation according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight.
Optionally, the effective diameter obtaining module includes:
the impulse response acquisition submodule is used for transforming the frequency domain channel estimation to the time domain to obtain channel impulse response;
a power delay distribution obtaining submodule, configured to obtain power delay distribution of each sample point in the channel impulse response;
the power sequencing submodule is used for carrying out power sequencing according to the power delay distribution of each sampling point;
the power determining submodule of the noise and the interference is used for determining the power of the noise and the interference according to the power sequence and the maximum effective path number;
a power threshold determining submodule for determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power sequence;
and the effective path determining submodule is used for taking the sampling points of which the power is greater than the power threshold in each sampling point as effective paths.
Optionally, the frequency offset estimation module includes:
the effective path correlation value acquisition submodule is used for acquiring an effective path correlation value of each effective path;
and the frequency offset estimation obtaining submodule is used for carrying out phase extraction on the effective path correlation value of each effective path and obtaining the frequency offset estimation of each effective path according to the phase extracted by the effective path correlation value.
Optionally, the weighted average frequency offset estimation module includes:
the power sum obtaining submodule is used for obtaining the power sum of the useful signal power of each effective path;
a combining weight obtaining submodule, configured to use a ratio of a useful signal power of each effective path to a sum of powers of the useful signal powers as a combining weight of each effective path;
and the weighted average frequency offset estimation submodule is used for carrying out weighted combination on the frequency offset estimation of each effective path by the combination weight to obtain the weighted average frequency offset estimation.
Optionally, when the method is applied to an OFDM system, the impulse response obtaining sub-module is configured to:
transforming the frequency domain channel estimation to a time domain by performing Inverse Fast Fourier Transform (IFFT) on the frequency domain channel estimation to obtain the channel impulse response;
the formula of the IFFT includes:
Figure BDA0001217325830000081
wherein,
Figure BDA0001217325830000082
representing the frequency domain channel estimation of the ith CRS OFDM symbol in the time direction and the kth CRS RE in the frequency direction;
Figure BDA0001217325830000083
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFTK denotes a total number of CRS REs in a frequency direction, and L denotes a total number of CRS symbols in a time direction;
wherein, when the IFFT is performed, N isFFTWhen the frequency domain channel estimation is larger than K, the frequency domain channel estimation on the I CRS OFDM symbol is compensated with 0 to ensure that the frequency domain channel estimation is carried out on the I CRS OFDM symbolThe length of the frequency domain channel estimate on the ith CRS OFDM symbol is equal to the NFFT(ii) a When N is presentFFTWhen the frequency domain channel estimation is less than or equal to K, taking N in the frequency domain channel estimation on the l-th CRS OFDM symbolFFTThe IFFT is performed for each sample point.
Optionally, when applied to an OFDM system, the power delay profile obtaining sub-module is configured to:
carrying out power averaging on the channel impulse response calculated by each CRS OFDM symbol to obtain the power delay distribution PDP;
wherein the formula for performing the power averaging comprises:
Figure BDA0001217325830000084
wherein,
Figure BDA0001217325830000085
represents the power of the nth sample in the PDP,
Figure BDA0001217325830000086
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFT。
Optionally, when applied to an OFDM system, the power sequencing sub-module is configured to:
delaying the power sequence in the power distribution
Figure BDA0001217325830000087
Sequencing according to the sequence of the power from large to small to obtain the power sequence, wherein the power sequence comprises a new sequence
Figure BDA0001217325830000088
Wherein
Figure BDA0001217325830000089
The noise and interference power determination sub-module comprises:
a noise and interference sample point determining submodule for sequencing the front of the maximum power in each sample point according to the power
Figure BDA00012173258300000810
Determining other sampling points except the individual sampling points as noise and interference sampling points;
the noise and interference power acquisition submodule is used for acquiring the noise and interference power according to a power calculation formula of the noise and interference sampling points;
the calculation formula of the power of the noise and interference sampling points comprises the following steps:
Figure BDA0001217325830000091
wherein,
Figure BDA0001217325830000092
representing the number of said maximum effective diameters, NFFTThe total number of the sample points of the channel impulse response is equal to NFFT，σ2Representing the power of the noise and interference samples.
Optionally, when applied to an OFDM system, the power threshold determining sub-module is configured to:
determining the power threshold by using a power threshold calculation formula according to the power of the noise and the interference and the maximum power in the power sequence;
the power threshold calculation formula includes:
Figure BDA0001217325830000093
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing said noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure BDA0001217325830000094
representing the maximum power in the power sequence.
Optionally, when the OFDM system is applied, the effective path correlation value obtaining sub-module is configured to:
calculating effective paths at the same position on adjacent CRS OFDM symbols by using a correlation value calculation formula to carry out effective path correlation values;
the correlation value calculation formula includes:
Figure BDA0001217325830000095
wherein,
Figure BDA0001217325830000096
an effective path correlation value representing the nth effective path,
Figure BDA0001217325830000097
sample i of the channel impulse response representing the i-th CRSOFDM symbol in the time directionnThe value of (a) is,
Figure BDA0001217325830000098
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sampling point of the N-th effective diameter, NpathIndicating the number of effective paths.
Optionally, when applied to an OFDM system, the frequency offset estimation obtaining sub-module includes:
the phase extraction submodule is used for extracting the phase of the effective diameter correlation value of each effective diameter by utilizing a phase calculation formula;
the frequency offset estimation determining submodule is used for acquiring the frequency offset estimation of each effective path according to the phase extracted by the correlation value of each effective path by using a frequency offset calculation formula;
wherein the phase calculation formula includes:
Figure BDA0001217325830000101
wherein,
Figure BDA0001217325830000102
the phase of the effective path correlation value representing the nth effective path,
Figure BDA0001217325830000103
effective path correlation value, N, representing the nth effective pathpathRepresenting the number of effective paths;
the frequency offset calculation formula comprises:
Figure BDA0001217325830000104
wherein,
Figure BDA0001217325830000105
and T represents the time interval of adjacent CRS OFDM symbols.
Optionally, when applied to an OFDM system, the power sum obtaining sub-module includes:
a useful signal power acquisition sub-module for, for each of the effective paths: comparing the value obtained by subtracting the noise and interference power from the power of the effective path with zero, and taking the maximum value of the two as the useful signal power of the effective path to obtain the useful signal power of each effective path;
the power sum determining submodule is used for acquiring the power sum of the useful signal power of each effective path by using a power sum formula;
wherein the power summing formula comprises:
Figure BDA0001217325830000106
wherein,
Figure BDA0001217325830000107
represents the sum of the powers of the two or more,
Figure BDA0001217325830000108
represents the power of the nth effective path,
Figure BDA0001217325830000109
representing the useful signal power, σ, of the nth effective path2Power, N, representing the noise and interference samplespathIndicating the number of effective paths.
Optionally, when applied to an OFDM system, the weighted average frequency offset estimation sub-module is configured to:
merging the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain the weighted average frequency offset estimation;
wherein the weighted average frequency offset formula comprises:
Figure BDA0001217325830000111
wherein f isoRepresenting the weighted average frequency offset estimate, and,
Figure BDA0001217325830000112
frequency offset estimate, w, representing the nth effective pathnThe combining weights representing the frequency offset estimate for the nth effective path,
Figure BDA0001217325830000113
represents the sum of the powers of the two or more,
Figure BDA0001217325830000114
representing the useful signal power of the nth effective path.
Optionally, the doppler spread estimation module includes:
the root-mean-square frequency offset expansion obtaining sub-module is used for obtaining the root-mean-square frequency offset expansion by utilizing a root-mean-square expansion calculation formula according to the frequency offset estimation of each effective diameter, the weighted average frequency offset estimation and the combining weight of each effective diameter;
a Doppler spread estimation submodule for taking the root mean square spread as the Doppler spread estimate;
wherein the root mean square spread calculation formula includes:
Figure BDA0001217325830000115
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure BDA0001217325830000116
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting said weighted average frequency offset estimate, NpathIndicating the number of effective paths.
The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects:
obtaining an effective path according to the channel impulse response; obtaining effective path correlation values of each effective path, and obtaining frequency offset estimation of each effective path according to the phase of the effective path correlation values; calculating a combining weight according to the power of each effective path, and performing weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation; and obtaining root-mean-square frequency offset expansion as Doppler expansion estimation according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight. The method can solve the problem that conventional frequency offset estimation is not applicable when each multi-path direct-view path component is large and carries different frequency offsets in a high-speed scene, and can effectively estimate the frequency offset of a channel. Furthermore, the weight of each effective path and the weighted average frequency offset estimation can be calculated according to the useful signal power of each effective path and the power sum of the useful signal power, the root mean square extension of each effective path is obtained to be used as the Doppler extension, the problems that a uniform scattering model is not established and a Bessel function is not applicable in the traditional Doppler estimation method can be avoided, and the Doppler extension under a high-speed moving scene can be obtained.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a flow diagram illustrating a method for determining frequency offset and Doppler spread in a high-speed mobile scenario in accordance with an exemplary embodiment;
fig. 2 is a flowchart illustrating a method for obtaining an effective path according to the embodiment shown in fig. 1;
FIG. 3 is a flow chart illustrating a method for determining a frequency offset estimate of an effective path according to the embodiment shown in FIG. 1;
FIG. 4 is a flow chart illustrating a method of determining a weighted average frequency offset estimate according to the embodiment shown in FIG. 1;
FIG. 5 is a flow chart of a method for determining noise and interference power according to the embodiment shown in FIG. 2;
FIG. 6 is a flow chart illustrating a method for obtaining a power sum of useful signal powers of an effective path according to the embodiment shown in FIG. 2;
FIG. 7 is a flow chart illustrating a method of determining a Doppler spread estimate according to the embodiment shown in FIG. 1;
FIG. 8 is a block diagram illustrating an apparatus for determining frequency offset and Doppler spread in a high-speed motion scenario in accordance with an exemplary embodiment;
FIG. 9 is a block diagram of an effective path acquisition module according to the embodiment shown in FIG. 8;
FIG. 10 is a block diagram of a frequency offset estimation module according to the embodiment shown in FIG. 8;
FIG. 11 is a block diagram of a weighted average frequency offset estimation module according to the embodiment shown in FIG. 8;
FIG. 12 is a block diagram of a noise and interference power determination sub-module according to the embodiment shown in FIG. 9;
FIG. 13 is a block diagram of a frequency offset estimation acquisition sub-module according to the embodiment shown in FIG. 10;
FIG. 14 is a block diagram of a power sum acquisition sub-module according to the embodiment shown in FIG. 11;
figure 15 is a block diagram of a doppler spread estimation module according to the embodiment shown in figure 8.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
Before describing particular embodiments, it is necessary to first describe the terms referred to in this disclosure. Frequency deviation: the amplitude of Frequency-modulated wave Frequency swing generally refers to a Frequency deviation between a network-side transmission signal and a local crystal Frequency of a terminal, and accurate Frequency deviation estimation can ensure that an AFC (automatic Frequency Control, chinese) in an OFDM (Orthogonal Frequency division multiplexing, chinese) system stably operates, so that the Frequency deviation is approximately zero, and ICI (Inter-Carrier Interference, chinese) in the system is reduced.
The doppler phenomenon is a spectrum divergence phenomenon caused by a moving speed, when a transmitting end and a receiving end make a relative motion, a signal frequency of the receiving end is shifted, and a doppler shift is generally called doppler spread and represents a fading rate of a channel. The effect on the received signal can be seen as doppler spread or spectral broadening of the transmitted signal frequency rather than as a frequency shift, with the maximum doppler shift being a measure of the doppler spectral broadening and a measure of the time-varying characteristics of the wireless channel. For a terminal of a wireless communication system, doppler spreading is expressed in that the faster the terminal moves, the faster the channel experienced by its received signal changes (fades) per unit time, and the more the spectrum of the received signal diverges. Maximum doppler spread f in a wireless channelmaxFrom the moving speed v and the carrier frequency fcCo-determining, i.e. fmax＝v·fc/c0. Wherein, c0Indicating the speed of light. Accurate Doppler spread estimation can provide important reference for channel estimation in a system, ensure channel estimation performance and further improve downlink receiving link performance.
The high-speed rail is covered by a private network along the line, and the network distribution mode usually adopts a BBU + RRU mode, that is, each base station is composed of one BBU and a plurality of RRUs, so that the coverage range of each base station can be effectively enlarged, the number of the base stations is reduced, and the network distribution cost is reduced. However, the network deployment method causes a terminal moving at a high speed among a plurality of RRUs in the same base station to receive wireless signals from the plurality of RRUs at the same time, and because the included angles between the terminal and the RRUs are different, doppler frequency shifts carried by the paths are different. Therefore, when the doppler shifts on the paths are different, the spectrum of the received signal is spread to form doppler spread.
Currently, for a conventional channel, frequency offset estimation and doppler spread are mainly calculated based on correlation values of two adjacent CRS (Cell-Specific Reference Signals, chinese) symbol channel estimates in the time direction, and the method can work well in most scenarios. However, in a high-speed moving scene, such as the high-speed rail scene mentioned above, the performance of the high-speed rail channel may be degraded to some extent because the direct-view path component of each multipath of the high-speed rail channel is larger and the scattering path component is smaller; the frequency offset carried by each multipath is related to factors such as the speed of the terminal, the included angle between the terminal and each RRU and the like, and the premise of the frequency offset estimation and Doppler spread application used in the prior art is that each multipath in a channel carries the same frequency offset and the channel meets Rayleigh fading, and is not suitable for a scene involving high-speed movement any more.
In addition, in recent years, with the rapid development of the construction of high-speed rails in china, according to the scheme of planning the medium-long-term railway network in china, the mileage of a high-speed railway with a speed of 200 km or more in china will exceed 30000 km in 2020, and therefore how to experience the extremely fast 4G service on a train traveling at a high speed is becoming an urgent problem to be solved.
Fig. 1 is a flowchart illustrating a method for determining frequency offset and doppler spread in a high-speed moving scene according to an exemplary embodiment, where the method includes the following steps:
step 101, obtaining an effective path according to the channel impulse response.
The manner of obtaining the effective diameter adopted by the present disclosure will be described in detail in the embodiment of fig. 2 below.
102, obtaining effective diameter correlation values of each effective diameter, and obtaining frequency offset estimation of each effective diameter according to the phase of the effective diameter correlation values.
Based on the effective path obtained in step 101, step 102 is a frequency offset estimation for the effective path, which should include an estimation of the phase of the effective path correlation value and the effective path correlation value. The specific embodiment is described in detail in the example of fig. 3 later.
And 103, calculating combining weights according to the power of each effective path, and performing weighted combination on the frequency offset estimation of each effective path by using the combining weights to obtain weighted average frequency offset estimation.
The manner of weighted average frequency offset estimation will be described in detail in the embodiment of fig. 4.
And 104, obtaining root-mean-square frequency offset expansion as Doppler expansion estimation according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight.
In the conventional technology, the method for calculating the doppler spread by using the bezier function is only applicable to a uniform scattering model, so that in a high-speed moving scene related to this embodiment, in order to avoid the problem that the uniform scattering model is not established and the bezier function is not applicable, the doppler spread may be obtained by obtaining the root mean square spread of each effective diameter, and a specific implementation manner of the method is described in detail below.
In summary, the method for determining frequency offset and doppler spread in a high-speed mobile scenario provided by the present disclosure can obtain an effective path and an effective path correlation value of each effective path according to a channel impulse response, and obtain a frequency offset estimate of each effective path according to a phase of the effective path correlation value; calculating a combining weight according to the power of each effective path, and performing weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation; and then, according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight, obtaining the root-mean-square frequency offset expansion as the Doppler expansion estimation. The method can solve the problem that conventional frequency offset estimation is not applicable when each multi-path direct-view path component is large and carries different frequency offsets in a high-speed scene, and can effectively estimate the frequency offset of a channel. Furthermore, the weight and weighted average frequency offset estimation of each effective path can be calculated according to the useful signal power of each effective path and the power sum of the useful signal power, the root mean square extension of each effective path is obtained to be used as Doppler extension, the problems that a uniform scattering model is not established and a Bessel function is not applicable in a traditional Doppler estimation method can be avoided, and therefore Doppler extension under a high-speed moving scene can be obtained.
Exemplarily, fig. 2 is a flowchart of an obtaining method of an effective path according to the embodiment shown in fig. 1, and as shown in fig. 2, the obtaining of an effective path according to a channel impulse response in step 101 in fig. 1 includes the following steps:
step 1011, transforming the frequency domain channel estimation to the time domain to obtain the channel impulse Response (CIR for short).
Wherein, the channel impulse response is time domain channel estimation, the channel estimation is transformed from the frequency domain to the time domain, Inverse Fourier transform or Inverse Fast Fourier Transform (IFFT) may be adopted, and after the CIR in the time domain is obtained, the operation of obtaining power delay distribution (PDP) in step 1012 may be performed.
For example, when applied to an OFDM system, the frequency domain channel estimate may be transformed to the time domain by performing IFFT on the frequency domain channel estimate, resulting in a channel impulse response.
Wherein, the formula of the IFFT comprises:
Figure BDA0001217325830000161
wherein,
Figure BDA0001217325830000162
representing the frequency domain channel estimation of the I & ltth & gt CRS OFDM symbol in the time direction and the k & ltth & gt CRS RE (English: Resource Element, Chinese: Resource Element) in the frequency direction;
Figure BDA0001217325830000163
value of nth sample point of channel impulse response, N, representing the l CRS OFDM symbolFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFTK denotes the total number of CRS REs in the frequency direction, and L denotes the total number of CRS symbols in the time direction.
Note that, when performing IFFT, N is the number NFFTWhen the frequency domain channel estimation is larger than K, the frequency domain channel estimation on the first CRS OFDM symbol is complemented by 0, so that the length of the frequency domain channel estimation on the first CRS OFDM symbol is equal to NFFT(ii) a When N is presentFFTWhen the frequency domain channel estimation is less than or equal to K, taking N in the frequency domain channel estimation on the first CRS OFDM symbolFFTThe samples are subjected to IFFT.
Illustratively, when the channel bandwidth is 10M, K is 100, and N may be setFFTIs 128, when N isFFTIf the frequency domain channel estimation length is larger than K, the operation of 0 complementing is needed to be carried out on the frequency domain channel estimation on the ith CRS OFDM symbol, so that the length of the frequency domain channel estimation on the ith CRS OFDM symbol is equal to 128.
Step 1012, obtain the power delay distribution of each sample point in the channel impulse response.
Illustratively, when applied to an OFDM system, the steps comprise: and performing power average on the channel impulse response calculated by each CRS OFDM symbol to obtain the PDP.
Wherein, the formula for carrying out power averaging comprises:
Figure BDA0001217325830000164
wherein,
Figure BDA0001217325830000165
indicating the power of the nth sample in the PDP,
Figure BDA0001217325830000166
value of nth sample point of channel impulse response, N, representing the l CRS OFDM symbolFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFT。
And 1013, performing power sequencing according to the power delay distribution of each sampling point.
Illustratively, when applied to an OFDM system, the steps comprise: delaying power sequences in a distribution
Figure BDA0001217325830000167
Sequencing according to the sequence of the power from large to small to obtain power sequencing, wherein the power sequencing comprises a new sequence
Figure BDA0001217325830000168
Wherein
Figure BDA0001217325830000169
After all the samples of the PDP are obtained by the power averaging formula in step 1012, the calculated samples are used
Figure BDA0001217325830000171
The values are sorted, the power of each sampling point can be sorted according to the sequence of the power from large to small, and the sorted result can be represented as:
Figure BDA0001217325830000172
wherein inIndexes the sorted sequence.
And 1014, determining the power of the noise and the interference according to the power sequence and the maximum effective path number.
The power of the noise and the interference may be determined according to the power sequence and the number of the maximum effective paths, where the number of the maximum effective paths is preset, and the specific value may be determined according to the bandwidth.
Step 1015, determine the power threshold for screening the effective path according to the power of the noise and the interference and the maximum power in the power sequence.
Illustratively, when applied to an OFDM system, this step may determine the power threshold based on the power of the noise and interference and the maximum power in the power rank using a power threshold calculation formula comprising:
Figure BDA0001217325830000173
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure BDA0001217325830000174
representing the maximum power in the power sequence.
Where ρ isnoiseAnd ρmaxPathIt can also be determined according to the bandwidth, for example, when the bandwidth of the channel is 10M, pnoiseMay be set to 3, and ρmaxPathMay be provided as 1/64.
Step 1016, the sampling points with the power greater than the power threshold in each sampling point are used as the effective path.
After the power threshold is determined in step 1015, the samples with power greater than the power threshold are determined as the effective paths, and the number of effective paths is recorded, where the number of effective paths can be NpathAnd (4) showing. For example, assuming that the number of the samples greater than the power threshold is 6, the 6 samples are taken as the effective path, and N ispathIt is equal to 6.
Illustratively, fig. 3 is a flowchart illustrating a method for determining a frequency offset estimate of an effective path according to the embodiment shown in fig. 1, and as shown in fig. 3, the obtaining of an effective path correlation value of each effective path and obtaining a frequency offset estimate of each effective path according to a phase of the effective path correlation value in step 102 in fig. 1 includes the following steps:
step 1021, obtaining the effective path correlation value of each effective path.
The correlation value of each effective path may be understood as a correlation value of channel impulse responses of two adjacent CRSOFDM (Orthogonal Frequency Division Multiplexing, chinese) symbols of the effective path in the time direction, and a specific embodiment thereof is described in detail below.
For example, the correlation value calculation formula may be used to calculate effective path correlation values of the same position on adjacent CRS OFDM symbols, where the correlation value calculation formula includes:
Figure BDA0001217325830000181
wherein,
Figure BDA0001217325830000182
an effective path correlation value representing the nth effective path,
Figure BDA0001217325830000183
sample i of the channel impulse response representing the i-th CRSOFDM symbol in the time directionnThe value of (a) is,
Figure BDA0001217325830000184
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sample point of the nth effective diameter, NpathIndicating the number of effective paths.
Step 1022, performing phase extraction on the effective path correlation value of each effective path, and obtaining the frequency offset estimation of each effective path according to the phase extracted from the effective path correlation value.
For example, when applied to an OFDM system, the effective path correlation value of each effective path may be first phase-extracted using a phase calculation formula. The phase calculation formula includes:
Figure BDA0001217325830000185
wherein,
Figure BDA0001217325830000186
the phase of the effective path correlation value representing the nth effective path,
Figure BDA0001217325830000187
effective path correlation value, N, representing the nth effective pathpathIndicating the number of effective paths.
And then, obtaining the frequency offset estimation of each effective path according to the phase extracted from the correlation value of each effective path by using a frequency offset calculation formula, wherein the frequency offset calculation formula comprises the following steps:
Figure BDA0001217325830000188
wherein,
Figure BDA0001217325830000189
and T represents the time interval of adjacent CRS OFDM symbols.
Exemplarily, fig. 4 is a flowchart of a method for determining a weighted average frequency offset estimation according to the embodiment shown in fig. 1, and as shown in fig. 4, the step 103 in fig. 1 mentioned above calculates combining weights according to powers of respective effective paths, and performs weighted combining on the frequency offset estimation of each effective path by using the combining weights to obtain the weighted average frequency offset estimation, which includes the following steps:
and step 1031, acquiring the power sum of the useful signal power of each effective path.
The useful signal power of each effective path can be obtained by subtracting the noise and interference power from the power of each effective path, comparing the result with 0, and selecting the larger one as the useful signal power of the effective path.
Step 1032, the ratio of the useful signal power of each effective path to the power sum of the useful signal power is used as the combining weight of each effective path.
And 1033, performing weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation.
The above steps may be understood as that the proportion of the total power obtained in step 1032 of the useful signal power of each effective path is used as the weight of the effective path, and then the frequency offset estimation of each effective path is weighted and averaged according to the weight of each effective path, so as to obtain the weighted average frequency offset estimation.
Optionally, when applied to an OFDM system, the step may include: and taking the ratio of the useful signal power of each effective path to the power sum of the useful signal power as the weight of each effective path, and combining the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain the weighted average frequency offset estimation. Wherein the weighted average frequency offset formula comprises:
Figure BDA0001217325830000191
wherein f isoRepresenting a weighted average frequency offset estimate of the frequency offset,
Figure BDA0001217325830000192
frequency offset estimate, w, representing the nth effective pathnRepresenting the weight of the frequency offset estimate for the nth effective path,
Figure BDA0001217325830000193
which represents the sum of the powers,
Figure BDA0001217325830000194
representing the useful signal power of the nth effective path.
For example, fig. 5 is a flowchart of a method for determining power of noise and interference according to the embodiment shown in fig. 2, and as shown in fig. 5, the step 1014 determines power of noise and interference according to power rank and maximum effective path number, which includes the following steps:
10141, according to the power sequence, the front with the maximum power in each sampling point is selected
Figure BDA0001217325830000195
Samples other than the one are determined as noise and interference samples.
Step 10142, obtaining the power of the noise and the interference according to the power calculation formula of the noise and the interference sampling points. Wherein, the formula for calculating the power of the noise and interference samples comprises:
Figure BDA0001217325830000201
wherein,
Figure BDA0001217325830000202
representing the number of maximum effective diameters, NFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFTDenotes σ in Power ordering2Representing the power of the noise and interference samples.
That is, the above-mentioned samples except the sample point with the maximum power
Figure BDA0001217325830000203
The other samples except the individual sample
Figure BDA0001217325830000204
Can be regarded as noise and interference sampling points, and can utilize the sampling points to carry out the power sigma of the noise and interference sampling points2The calculation of (a) is performed,
Figure BDA0001217325830000205
the value of (c) may be determined according to the bandwidth, for example when the bandwidth of the channel is 10M (mega),
Figure BDA0001217325830000206
may be set to 8.
Illustratively, fig. 6 is a flowchart of a method for obtaining the power sum of the useful signal power of the effective paths according to the embodiment shown in fig. 2, and as shown in fig. 6, when applied to the OFDM system, the step 1031 in fig. 3 obtains the power sum of the useful signal power of each effective path, which includes the following steps:
step 10311, for each effective diameter: and comparing the value obtained by subtracting the power of the noise and the interference from the power of the effective path with zero, and taking the maximum value of the power of the effective path and the power of the noise and the interference as the useful signal power of the effective path to obtain the useful signal power of each effective path.
That is, as for the power after removing the power of the noise and the interference in the power of each effective path, if it is larger than zero, the power after removing the power of the noise and the interference is taken as the useful signal power of the effective path, and if it is smaller than zero, zero is taken as the useful signal power of the effective path, which can also be understood as filtering the useful signal power.
And step 10312, obtaining the power sum of the useful signal power of each effective path by using a power sum formula. The power summing equation includes:
Figure BDA0001217325830000207
wherein,
Figure BDA0001217325830000208
which represents the sum of the powers,
Figure BDA0001217325830000209
represents the power of the nth effective path,
Figure BDA00012173258300002010
representing the power of the useful signal of the nth effective path, σ2Power, N, representing noise and interference samplespathIndicating the number of effective paths.
For example, fig. 7 is a flowchart illustrating a method for determining a doppler spread estimate according to the embodiment shown in fig. 1, and as shown in fig. 7, when applied to an OFDM system, the step 104 of fig. 1 obtains a root-mean-square frequency offset spread according to frequency offset estimates of respective effective paths, weighted-average frequency offset estimate and combining weights, and may include the following steps:
step 1041, according to the frequency offset estimation of each effective diameter, the weighted average frequency offset estimation and the combining weight of each effective diameter, a root mean square expansion calculation formula is used to obtain root mean square frequency offset expansion.
Wherein, the root mean square spread calculation formula comprises:
Figure BDA0001217325830000211
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure BDA0001217325830000212
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting a weighted average frequency offset estimate, NpathIndicating the number of effective paths.
In step 1042, the root mean square spread is used as the doppler spread estimate.
The above calculation method of root mean square can be applied to a scenario where the channel does not satisfy the rayleigh fading condition, that is, the channel does not satisfy the model of uniform scattering, and therefore the calculation method is suitable for the calculation of the doppler spread of the channel in a high-speed moving scenario.
Therefore, the method and the device can solve the problem that the conventional frequency offset estimation method is not applicable any more due to the fact that direct-view path components of various multi-paths are large and different frequency offsets are carried in the high-speed scene, can obtain frequency offset estimation in the high-speed mobile scene, and can avoid the problems that a uniform scattering model is not established and a Bessel function is not applicable in the traditional Doppler estimation method, so that Doppler expansion in the high-speed mobile scene can be determined.
Fig. 8 is a block diagram illustrating an apparatus for determining frequency offset and doppler spread in a high-speed moving scene according to an exemplary embodiment, and as shown in fig. 8, the apparatus 800 includes:
an effective path obtaining module 810, configured to obtain an effective path according to the channel impulse response.
The frequency offset estimation module 820 is configured to obtain an effective path correlation value of each effective path, and obtain a frequency offset estimation of each effective path according to a phase of the effective path correlation value.
And a weighted average frequency offset estimation module 830, configured to calculate a combining weight according to the power of each effective path, and perform weighted combining on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation.
The doppler spread estimation module 840 is configured to obtain root mean square frequency offset spread as doppler spread estimation according to the frequency offset estimation, the weighted average frequency offset estimation, and the combining weight of each effective path.
Optionally, fig. 9 is a block diagram of an effective path obtaining module shown in the embodiment shown in fig. 8, and as shown in fig. 9, the effective path obtaining module 810 includes:
the impulse response obtaining sub-module 811 is configured to transform the frequency domain channel estimation to the time domain to obtain a channel impulse response.
And a power delay profile obtaining sub-module 812, configured to obtain a power delay profile of each sample in the channel impulse response.
The power sorting sub-module 813 is configured to perform power sorting according to the power delay distribution of each sampling point.
And a noise and interference power determination sub-module 814, configured to determine the power of the noise and interference according to the power rank and the maximum effective path number.
And a power threshold determination sub-module 815 for determining a power threshold for screening the effective path according to the power of the noise and the interference and the maximum power in the power sequence.
The effective path determining sub-module 816 is configured to use a sample point with a power greater than the power threshold in each sample point as the effective path.
Optionally, fig. 10 is a block diagram of a frequency offset estimation module according to the embodiment shown in fig. 8, and as shown in fig. 10, the frequency offset estimation module 820 includes:
the effective path correlation value obtaining sub-module 821 is configured to obtain an effective path correlation value of each effective path.
The frequency offset estimation obtaining submodule 822 is configured to perform phase extraction on the effective path correlation value of each effective path, and obtain a frequency offset estimation of each effective path according to the phase extracted from the effective path correlation value.
Alternatively, fig. 11 is a block diagram of a weighted average frequency offset estimation module according to the embodiment shown in fig. 8, where, as shown in fig. 11, the weighted average frequency offset estimation module 830 includes:
the power sum obtaining sub-module 831 is configured to obtain the power sum of the useful signal power of each effective path.
A combining weight obtaining sub-module 832 for taking the ratio of the useful signal power of each effective path to the power sum of the useful signal power as the combining weight of each effective path.
And the weighted average frequency offset estimation sub-module 833 is configured to perform weighted combining on the frequency offset estimates of the effective paths by using the combining weights to obtain a weighted average frequency offset estimate.
Optionally, when applied to the OFDM system, the impulse response obtaining sub-module 811 is configured to:
transforming the frequency domain channel estimation to a time domain by performing Inverse Fast Fourier Transform (IFFT) on the frequency domain channel estimation to obtain channel impulse response;
the formulation of the IFFT includes:
Figure BDA0001217325830000231
wherein,
Figure BDA0001217325830000232
representing the frequency domain channel estimation of the ith CRS OFDM symbol in the time direction and the kth CRS RE in the frequency direction;
Figure BDA0001217325830000233
value of nth sample point of channel impulse response, N, representing the l CRS OFDM symbolFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFTK denotes a total number of CRS REs in a frequency direction, and L denotes a total number of CRS symbols in a time direction;
wherein, when performing IFFT, when NFFTWhen the frequency domain channel estimation is larger than K, the frequency domain channel estimation on the first CRS OFDM symbol is complemented by 0, so that the length of the frequency domain channel estimation on the first CRS OFDM symbol is equal to NFFT(ii) a When N is presentFFTWhen K is less than or equal to K, taking N in the frequency domain channel estimation on the first CRSOFDM symbolFFTThe samples are subjected to IFFT.
Optionally, when applied to the OFDM system, the power delay profile obtaining sub-module 812 is configured to:
carrying out power averaging on the channel impulse response calculated by each CRS OFDM symbol to obtain a power delay distribution PDP;
wherein, the formula for carrying out power averaging comprises:
Figure BDA0001217325830000234
wherein,
Figure BDA0001217325830000235
indicating the power of the nth sample in the PDP,
Figure BDA0001217325830000236
value of nth sample point of channel impulse response, N, representing the l CRS OFDM symbolFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFT。
Optionally, when applied to an OFDM system, the power ordering sub-module 813 is configured to:
delaying power sequences in a distribution
Figure BDA0001217325830000237
Sequencing according to the sequence of the power from large to small to obtain power sequencing, wherein the power sequencing comprises a new sequence
Figure BDA0001217325830000238
Wherein
Figure BDA0001217325830000239
Optionally, fig. 12 is a block diagram of a noise and interference power determination sub-module shown in the embodiment of fig. 9, and as shown in fig. 12, the noise and interference power determination sub-module 814 includes:
a noise and interference sample point determining submodule 8141 for sorting the front of the maximum power in each sample point according to the power
Figure BDA0001217325830000241
Samples other than the one are determined as noise and interference samples.
And the noise and interference power acquisition sub-module 8142 is used for acquiring the power of the noise and interference according to the power calculation formula of the noise and interference sampling points.
The formula for calculating the power of the noise and interference samples includes:
Figure BDA0001217325830000242
wherein,
Figure BDA0001217325830000243
representing the number of maximum effective diameters, NFFTThe number of IFFT points is represented, and the total number of the channel impulse response sample points is equal to NFFT，σ2Representing the power of the noise and interference samples.
Optionally, when applied to the OFDM system, the power threshold determining sub-module 815 is configured to:
and determining the power threshold by using a power threshold calculation formula according to the power of the noise and the interference and the maximum power in the power sequence.
The power threshold calculation formula comprises:
Figure BDA0001217325830000244
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure BDA0001217325830000245
representing the maximum power in the power sequence.
Optionally, when applied to the OFDM system, the effective path correlation value obtaining sub-module 821 is configured to:
calculating effective paths at the same position on adjacent CRS OFDM symbols by using a correlation value calculation formula to carry out effective path correlation values; the correlation value calculation formula includes:
Figure BDA0001217325830000246
wherein,
Figure BDA0001217325830000247
an effective path correlation value representing the nth effective path,
Figure BDA0001217325830000248
sample i of the channel impulse response representing the i-th CRSOFDM symbol in the time directionnThe value of (a) is,
Figure BDA0001217325830000249
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sample point of the nth effective diameter, NpathIndicating the number of effective paths.
Optionally, fig. 13 is a block diagram of a frequency offset estimation obtaining sub-module according to the embodiment shown in fig. 10, as shown in fig. 13, when applied to an OFDM system, the frequency offset estimation obtaining sub-module 822 includes:
and the phase extraction submodule 8221 is used for extracting the phase of the effective path correlation value of each effective path by using a phase calculation formula.
And the frequency offset estimation determining submodule 8222 is configured to obtain, by using a frequency offset calculation formula, a frequency offset estimation of each effective path according to the phase extracted from the correlation value of each effective path.
Wherein, the phase calculation formula includes:
Figure BDA0001217325830000251
wherein,
Figure BDA0001217325830000252
the phase of the effective path correlation value representing the nth effective path,
Figure BDA0001217325830000253
effective path correlation value, N, representing the nth effective pathpathIndicating the number of effective paths.
The frequency offset calculation formula comprises:
Figure BDA0001217325830000254
wherein,
Figure BDA0001217325830000255
and T represents the time interval of adjacent CRS OFDM symbols.
Alternatively, fig. 14 is a block diagram of a power sum obtaining sub-module according to the embodiment shown in fig. 11, and as shown in fig. 14, when applied to an OFDM system, the power sum obtaining sub-module 831 includes:
a useful signal power acquisition sub-module 8311 for, for each effective path: and comparing the value obtained by subtracting the power of the noise and the interference from the power of the effective path with zero, and taking the maximum value of the power of the effective path and the power of the noise and the interference as the useful signal power of the effective path to obtain the useful signal power of each effective path.
The power sum determination sub-module 8312 is configured to obtain a power sum of the useful signal power of each effective path by using a power sum formula.
Wherein the power summation formula comprises:
Figure BDA0001217325830000256
wherein,
Figure BDA0001217325830000257
which represents the sum of the powers,
Figure BDA0001217325830000258
represents the power of the nth effective path,
Figure BDA0001217325830000259
representing the power of the useful signal of the nth effective path, σ2Power, N, representing noise and interference samplespathIndicating the number of effective paths.
Optionally, when applied to the OFDM system, the weighted average frequency offset estimation sub-module 833 is configured to:
merging the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain weighted average frequency offset estimation;
wherein, the weighted average frequency offset formula comprises:
Figure BDA0001217325830000261
wherein f isoRepresenting a weighted average frequency offset estimate of the frequency offset,
Figure BDA0001217325830000262
frequency offset estimate, w, representing the nth effective pathnThe combining weights representing the frequency offset estimate for the nth effective path,
Figure BDA0001217325830000263
which represents the sum of the powers,
Figure BDA0001217325830000264
representing the useful signal power of the nth effective path.
Alternatively, fig. 15 is a block diagram of a doppler spread estimation module according to the embodiment shown in fig. 8, as shown in fig. 15, the doppler spread estimation module 840 includes:
the rms frequency offset expansion obtaining sub-module 841 is configured to obtain the rms frequency offset expansion by using an rms expansion calculation formula according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight of each effective path.
A doppler spread estimation sub-module 842 for estimating the rms spread as the doppler spread.
Wherein, the root mean square spread calculation formula comprises:
Figure BDA0001217325830000265
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure BDA0001217325830000266
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting a weighted average frequency offset estimate, NpathIndicating the number of effective paths.
In summary, the method and the device can solve the problem that the conventional frequency offset estimation method is not applicable any more due to the fact that direct-view path components of various multipaths are large and different frequency offsets are carried in the high-speed scene, can obtain frequency offset estimation in the high-speed mobile scene, and can avoid the problems that a uniform scattering model is not established and a Bessel function is not applicable in the conventional Doppler estimation method, so that Doppler expansion in the high-speed mobile scene can be determined.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (22)

1. A method for determining frequency offset and Doppler spread in a high-speed mobile scene is characterized by comprising the following steps:
obtaining an effective path according to the channel impulse response;
obtaining an effective path correlation value of each effective path, and obtaining a frequency offset estimation of each effective path according to the phase of the effective path correlation value, wherein the effective path correlation value is a correlation value of channel impulse responses of two adjacent CRS OFDM symbols of each effective path in the time direction;
calculating a combining weight according to the power of each effective path, and performing weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain a weighted average frequency offset estimation;
according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight, obtaining root-mean-square frequency offset expansion as Doppler expansion estimation;
the obtaining root-mean-square frequency offset extension according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation and the combining weight, as doppler extension estimation, includes:
according to the frequency offset estimation of each effective diameter, the weighted average frequency offset estimation and the merging weight of each effective diameter, the root mean square frequency offset expansion is obtained by using a root mean square expansion calculation formula;
using the root mean square spread as the Doppler spread estimate;
wherein the root mean square spread calculation formula includes:
Figure FDA0002207911740000011
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure FDA0002207911740000012
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting said weighted average frequency offset estimate, NpathIndicating the number of effective paths.
2. The method of claim 1, wherein obtaining the effective path according to the channel impulse response comprises:
transforming the frequency domain channel estimation to a time domain to obtain a channel impulse response;
acquiring power delay distribution of each sampling point in the channel impulse response;
performing power sequencing according to the power delay distribution of each sampling point;
determining the power of noise and interference according to the power sequence and the maximum effective path number;
determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power sequence;
taking the sampling points with the power greater than the power threshold in each sampling point as effective diameters;
when applied to an OFDM system, the determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power rank includes:
determining the power threshold by using a power threshold calculation formula according to the power of the noise and the interference and the maximum power in the power sequence;
the power threshold calculation formula includes:
Figure FDA0002207911740000021
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing said noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure FDA0002207911740000022
representing the maximum power in the power sequence.
3. The method of claim 1, wherein obtaining the effective path correlation value of each effective path and obtaining the frequency offset estimate of each effective path according to the phase of the effective path correlation value comprises:
obtaining effective diameter correlation values of each effective diameter;
and extracting the phase of the effective diameter correlation value of each effective diameter, and acquiring the frequency offset estimation of each effective diameter according to the phase extracted by the effective diameter correlation value.
4. The method of claim 1, wherein the calculating combining weights according to the power of each effective path, and performing weighted combining on the frequency offset estimates of each effective path with the combining weights to obtain a weighted average frequency offset estimate comprises:
acquiring the power sum of the useful signal power of each effective path;
taking the ratio of the useful signal power of each effective path to the power sum of the useful signal power as the combining weight of each effective path;
and carrying out weighted combination on the frequency offset estimation of each effective path by the combining weight to obtain the weighted average frequency offset estimation.
5. The method of claim 2, wherein transforming the frequency domain channel estimate to the time domain when applied to an orthogonal frequency division multiplexing, OFDM, system to obtain a channel impulse response comprises:
transforming the frequency domain channel estimation to a time domain by performing Inverse Fast Fourier Transform (IFFT) on the frequency domain channel estimation to obtain the channel impulse response;
the formula of the IFFT includes:
Figure FDA0002207911740000031
wherein,
Figure FDA0002207911740000032
representing the frequency domain channel estimation of the ith CRS OFDM symbol in the time direction and the kth CRS RE in the frequency direction;
Figure FDA0002207911740000033
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFTK denotes a total number of CRS REs in a frequency direction, and L denotes a total number of CRS symbols in a time direction;
wherein, when the IFFT is performed, N isFFTWhen the frequency domain channel estimation length is larger than K, the frequency domain channel estimation on the I CRS OFDM symbol is complemented by 0, and the length of the frequency domain channel estimation on the I CRS OFDM symbol is equal to the NFFT(ii) a When N is presentFFTWhen the frequency domain channel estimation is less than or equal to K, taking N in the frequency domain channel estimation on the l-th CRS OFDM symbolFFTThe IFFT is performed for each sample point.
6. The method of claim 2, wherein the obtaining the power delay profile of each sample in the channel impulse response when applied to an OFDM system comprises:
carrying out power averaging on the channel impulse response calculated by each CRS OFDM symbol to obtain the power delay distribution PDP;
wherein the formula for performing the power averaging comprises:
Figure FDA0002207911740000041
wherein,
Figure FDA0002207911740000042
represents the power of the nth sample in the PDP,
Figure FDA0002207911740000043
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFT。
7. The method of claim 2, wherein the power ordering according to the power delay profile of each sampling point when applied to an OFDM system comprises:
delaying the power sequence in the power distribution
Figure FDA0002207911740000044
Sequencing according to the sequence of the power from large to small to obtain the power sequence, wherein the power sequence comprises a new sequence
Figure FDA0002207911740000045
Wherein
Figure FDA0002207911740000046
The determining the power of the noise and the interference according to the power sequence and the maximum effective path number comprises:
according to the power sequence, the front with the maximum power in each sampling point is sequenced
Figure FDA0002207911740000047
Determining other sampling points except the individual sampling points as noise and interference sampling points;
acquiring the power of the noise and the interference according to a power calculation formula of the noise and the interference sampling points;
the calculation formula of the power of the noise and interference sampling points comprises the following steps:
Figure FDA0002207911740000048
wherein,
Figure FDA0002207911740000049
representing the number of said maximum effective diameters, NFFTThe total number of the sample points of the channel impulse response is equal to NFFT，σ2Representing the power of the noise and interference samples.
8. The method of claim 3, wherein the obtaining the effective path correlation value of each effective path when applied to the OFDM system comprises:
calculating effective paths at the same position on adjacent CRSOFDM symbols by using a correlation value calculation formula to carry out effective path correlation values;
the correlation value calculation formula includes:
Figure FDA0002207911740000051
wherein,
Figure FDA0002207911740000052
an effective path correlation value representing the nth effective path,
Figure FDA0002207911740000053
sample i representing channel impulse response of the ith CRS OFDM symbol in time directionnThe value of (a) is,
Figure FDA0002207911740000054
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sampling point of the N-th effective diameter, NpathIndicating the number of effective paths.
9. The method of claim 3, wherein when applied to an OFDM system, the performing phase extraction on the effective path correlation value of each effective path and obtaining the frequency offset estimate of each effective path according to the phase extracted from the effective path correlation value comprises:
carrying out phase extraction on the effective diameter correlation values of all the effective diameters by utilizing a phase calculation formula;
obtaining the frequency offset estimation of each effective path according to the phase extracted from the correlation value of each effective path by using a frequency offset calculation formula;
wherein the phase calculation formula includes:
Figure FDA0002207911740000055
wherein,
Figure FDA0002207911740000056
the phase of the effective path correlation value representing the nth effective path,
Figure FDA0002207911740000057
effective path correlation value, N, representing the nth effective pathpathRepresenting the number of effective paths;
the frequency offset calculation formula comprises:
Figure FDA0002207911740000061
wherein,
Figure FDA0002207911740000062
represents the frequency offset estimate for the nth effective path and T represents the time interval of the adjacent CRSOFDM symbol.
10. The method of claim 4, wherein the obtaining the power sum of the useful signal power of each effective path when applied to the OFDM system comprises:
for each of the effective diameters: comparing the value obtained by subtracting the noise and interference power from the power of the effective path with zero, and taking the maximum value of the two as the useful signal power of the effective path to obtain the useful signal power of each effective path;
acquiring the power sum of the useful signal power of each effective path by using a power sum formula;
wherein the power summing formula comprises:
Figure FDA0002207911740000063
wherein,
Figure FDA0002207911740000064
represents the sum of the powers of the two or more,
Figure FDA0002207911740000065
represents the power of the nth effective path,
Figure FDA0002207911740000066
representing the useful signal power, σ, of the nth effective path2Power, N, representing the noise and interference samplespathIndicating the number of effective paths.
11. The method of claim 4, wherein when applied to an OFDM system, the weighted combining the frequency offset estimates for each effective path with the combining weights to obtain the weighted average frequency offset estimate comprises:
merging the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain the weighted average frequency offset estimation;
wherein the weighted average frequency offset formula comprises:
Figure FDA0002207911740000071
wherein f isoRepresenting the weighted average frequency offset estimate, and,
Figure FDA0002207911740000072
frequency offset estimate, w, representing the nth effective pathnThe combining weights representing the frequency offset estimate for the nth effective path,
Figure FDA0002207911740000073
represents the sum of the powers of the two or more,
Figure FDA0002207911740000074
representing the useful signal power of the nth effective path.
12. An apparatus for determining frequency offset and doppler spread in a high-speed motion scenario, the apparatus comprising:
an effective path obtaining module, configured to obtain an effective path according to the channel impulse response;
a frequency offset estimation module, configured to obtain an effective path correlation value of each effective path, and obtain a frequency offset estimation of each effective path according to a phase of the effective path correlation value, where the effective path correlation value is a correlation value of channel impulse responses of two adjacent CRS OFDM symbols of each effective path in a time direction;
the weighted average frequency offset estimation module is used for calculating a combining weight according to the power of each effective path, and carrying out weighted combination on the frequency offset estimation of each effective path by using the combining weight to obtain weighted average frequency offset estimation;
a doppler spread estimation module, configured to obtain root mean square frequency offset spread as doppler spread estimation according to the frequency offset estimation of each effective path, the weighted average frequency offset estimation, and the combining weight;
the Doppler spread estimation module comprises:
the root-mean-square frequency offset expansion obtaining sub-module is used for obtaining the root-mean-square frequency offset expansion by utilizing a root-mean-square expansion calculation formula according to the frequency offset estimation of each effective diameter, the weighted average frequency offset estimation and the combining weight of each effective diameter;
a Doppler spread estimation submodule for taking the root mean square spread as the Doppler spread estimate;
wherein the root mean square spread calculation formula includes:
Figure FDA0002207911740000081
wherein f isDoppRepresenting the spread of the root-mean-square frequency offset,
Figure FDA0002207911740000082
frequency offset estimate, w, representing the nth effective pathnCombining weights, f, representing the frequency offset estimate of the nth effective pathoRepresenting said weighted average frequency offset estimate, NpathIndicating the number of effective paths.
13. The apparatus of claim 12, wherein the effective path obtaining module comprises:
the impulse response acquisition submodule is used for transforming the frequency domain channel estimation to the time domain to obtain channel impulse response;
a power delay distribution obtaining submodule, configured to obtain power delay distribution of each sample point in the channel impulse response;
the power sequencing submodule is used for carrying out power sequencing according to the power delay distribution of each sampling point;
the power determining submodule of the noise and the interference is used for determining the power of the noise and the interference according to the power sequence and the maximum effective path number;
a power threshold determining submodule for determining a power threshold for screening an effective path according to the power of the noise and the interference and the maximum power in the power sequence;
an effective path determining submodule, configured to use, as an effective path, a sampling point, where power of the sampling point is greater than the power threshold;
when applied to an OFDM system, the power threshold determination submodule is configured to:
determining the power threshold by using a power threshold calculation formula according to the power of the noise and the interference and the maximum power in the power sequence;
the power threshold calculation formula includes:
Figure FDA0002207911740000091
where Γ represents the power threshold, ρnoiseRepresenting the noise threshold coefficient, σ2Power, p, representing said noise and interference samplesmaxPathThe maximum path threshold coefficient is represented by the maximum path threshold coefficient,
Figure FDA0002207911740000092
representing the maximum power in the power sequence.
14. The apparatus of claim 12, wherein the frequency offset estimation module comprises:
the effective path correlation value acquisition submodule is used for acquiring an effective path correlation value of each effective path;
and the frequency offset estimation obtaining submodule is used for carrying out phase extraction on the effective path correlation value of each effective path and obtaining the frequency offset estimation of each effective path according to the phase extracted by the effective path correlation value.
15. The apparatus of claim 12, wherein the weighted average frequency offset estimation module comprises:
the power sum obtaining submodule is used for obtaining the power sum of the useful signal power of each effective path;
a combining weight obtaining submodule, configured to use a ratio of a useful signal power of each effective path to a sum of powers of the useful signal powers as a combining weight of each effective path;
and the weighted average frequency offset estimation submodule is used for carrying out weighted combination on the frequency offset estimation of each effective path by the combination weight to obtain the weighted average frequency offset estimation.
16. The apparatus of claim 13, wherein the impulse response obtaining sub-module, when applied to an OFDM system, is configured to:
transforming the frequency domain channel estimation to a time domain by performing Inverse Fast Fourier Transform (IFFT) on the frequency domain channel estimation to obtain the channel impulse response;
the formula of the IFFT includes:
Figure FDA0002207911740000101
wherein,
Figure FDA0002207911740000102
representing the frequency domain channel estimation of the ith CRS OFDM symbol in the time direction and the kth CRS RE in the frequency direction;
Figure FDA0002207911740000103
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFTK denotes a total number of CRS REs in a frequency direction, and L denotes a total number of CRS symbols in a time direction;
wherein, when the IFFT is performed, N isFFTWhen the CRS OFDM symbol is greater than K, the first CRS OFDM symbol is processedComplementing the frequency domain channel estimation on the number by 0 to enable the length of the frequency domain channel estimation on the ith CRS OFDM symbol to be equal to the NFFT(ii) a When N is presentFFTWhen the frequency domain channel estimation is less than or equal to K, taking N in the frequency domain channel estimation on the l-th CRS OFDM symbolFFTThe IFFT is performed for each sample point.
17. The apparatus of claim 13, wherein the power delay profile obtaining sub-module, when applied to an OFDM system, is configured to:
carrying out power averaging on the channel impulse response calculated by each CRS OFDM symbol to obtain the power delay distribution PDP;
wherein the formula for performing the power averaging comprises:
Figure FDA0002207911740000104
wherein,
Figure FDA0002207911740000105
represents the power of the nth sample in the PDP,
Figure FDA0002207911740000106
a value, N, of an nth sample point of a channel impulse response representing the l-th CRS OFDM symbolFFTThe total number of the sample points of the channel impulse response is equal to NFFT。
18. The apparatus of claim 13, wherein the power ordering sub-module, when applied to an OFDM system, is configured to:
delaying the power sequence in the power distribution
Figure FDA0002207911740000111
Sequencing according to the sequence of the power from large to small to obtain the power sequence, wherein the power sequence comprises a new sequence
Figure FDA0002207911740000112
Wherein
Figure FDA0002207911740000113
The noise and interference power determination sub-module comprises:
a noise and interference sample point determining submodule for sequencing the front of the maximum power in each sample point according to the power
Figure FDA0002207911740000114
Determining other sampling points except the individual sampling points as noise and interference sampling points;
the noise and interference power acquisition submodule is used for acquiring the noise and interference power according to a power calculation formula of the noise and interference sampling points;
the calculation formula of the power of the noise and interference sampling points comprises the following steps:
Figure FDA0002207911740000115
wherein,
Figure FDA0002207911740000116
representing the number of said maximum effective diameters, NFFTThe total number of the sample points of the channel impulse response is equal to NFFT，σ2Representing the power of the noise and interference samples.
19. The apparatus of claim 14, wherein the effective path correlation value obtaining sub-module, when applied to an OFDM system, is configured to:
calculating effective paths at the same position on adjacent CRS OFDM symbols by using a correlation value calculation formula to carry out effective path correlation values;
the correlation value calculation formula includes:
Figure FDA0002207911740000117
wherein,
Figure FDA0002207911740000118
an effective path correlation value representing the nth effective path,
Figure FDA0002207911740000119
sample i representing channel impulse response of the ith CRS OFDM symbol in time directionnThe value of (a) is,
Figure FDA00022079117400001110
sample i representing channel impulse response of the (l + 1) th CRS OFDM symbol in time directionnA value of (a), wherein the sample point inAs a sampling point of the N-th effective diameter, NpathIndicating the number of effective paths.
20. The apparatus of claim 14, wherein the frequency offset estimation obtaining sub-module, when applied to an OFDM system, comprises:
the phase extraction submodule is used for extracting the phase of the effective diameter correlation value of each effective diameter by utilizing a phase calculation formula;
the frequency offset estimation determining submodule is used for acquiring the frequency offset estimation of each effective path according to the phase extracted by the correlation value of each effective path by using a frequency offset calculation formula;
wherein the phase calculation formula includes:
Figure FDA0002207911740000121
wherein,
Figure FDA0002207911740000122
the phase of the effective path correlation value representing the nth effective path,
Figure FDA0002207911740000123
effective path correlation value, N, representing the nth effective pathpathRepresenting the number of effective paths;
the frequency offset calculation formula comprises:
Figure FDA0002207911740000124
wherein,
Figure FDA0002207911740000125
and T represents the time interval of adjacent CRS OFDM symbols.
21. The apparatus of claim 15, wherein the power sum obtaining sub-module, when applied to an OFDM system, comprises:
a useful signal power acquisition sub-module for, for each of the effective paths: comparing the value obtained by subtracting the noise and interference power from the power of the effective path with zero, and taking the maximum value of the two as the useful signal power of the effective path to obtain the useful signal power of each effective path;
the power sum determining submodule is used for acquiring the power sum of the useful signal power of each effective path by using a power sum formula;
wherein the power summing formula comprises:
Figure FDA0002207911740000131
wherein,
Figure FDA0002207911740000132
represents the sum of the powers of the two or more,
Figure FDA0002207911740000133
represents the power of the nth effective path,
Figure FDA0002207911740000134
representing the useful signal power, σ, of the nth effective path2Power, N, representing the noise and interference samplespathIndicating the number of effective paths.
22. The apparatus of claim 15, wherein the weighted average frequency offset estimation sub-module, when applied to an OFDM system, is configured to:
merging the frequency offset estimation of each effective path by using a weighted average frequency offset formula to obtain the weighted average frequency offset estimation;
wherein the weighted average frequency offset formula comprises:
Figure FDA0002207911740000135
wherein f isoRepresenting the weighted average frequency offset estimate, and,
Figure FDA0002207911740000136
frequency offset estimate, w, representing the nth effective pathnThe combining weights representing the frequency offset estimate for the nth effective path,
Figure FDA0002207911740000137
represents the sum of the powers of the two or more,
Figure FDA0002207911740000138
representing the useful signal power of the nth effective path.
CN201710058266.5A 2017-01-23 2017-01-23 Method and device for determining frequency offset and Doppler spread in high-speed mobile scene Active CN106789773B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201710058266.5A CN106789773B (en) 2017-01-23 2017-01-23 Method and device for determining frequency offset and Doppler spread in high-speed mobile scene

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201710058266.5A CN106789773B (en) 2017-01-23 2017-01-23 Method and device for determining frequency offset and Doppler spread in high-speed mobile scene

Publications (2)

Publication Number Publication Date
CN106789773A CN106789773A (en) 2017-05-31
CN106789773B true CN106789773B (en) 2020-03-17

Family

ID=58943168

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201710058266.5A Active CN106789773B (en) 2017-01-23 2017-01-23 Method and device for determining frequency offset and Doppler spread in high-speed mobile scene

Country Status (1)

Country Link
CN (1) CN106789773B (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109495407B (en) * 2017-09-13 2020-09-11 电信科学技术研究院 Channel estimation method, device, equipment and computer readable storage medium
CN109818885B (en) * 2017-11-22 2020-07-31 电信科学技术研究院 Channel estimation method, device, equipment and computer readable storage medium
CN110518921B (en) * 2018-05-21 2021-05-04 北京小米松果电子有限公司 Method, apparatus and storage medium for multipath combining and electronic device
CN112671489B (en) * 2020-12-17 2022-07-12 重庆邮电大学 Watson model-based short wave aviation mobile channel modeling method
CN114697179B (en) * 2020-12-30 2023-09-19 ***通信集团终端有限公司 Frequency offset estimation method, device, equipment and computer storage medium
CN113438189B (en) * 2021-06-23 2023-03-14 上海擎昆信息科技有限公司 Scene recognition method and device
CN114745240A (en) * 2022-04-08 2022-07-12 展讯通信（上海）有限公司 Method and device for determining frequency offset value of signal
CN116545825B (en) * 2023-07-06 2023-10-17 广东省新一代通信与网络创新研究院 Doppler frequency offset estimation method, system and device applying OFDM system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1588834A (en) * 2004-09-16 2005-03-02 北京天碁科技有限公司 Frequency deviation evaluation device and method
CN105007241A (en) * 2015-07-01 2015-10-28 杭州祥声通讯股份有限公司 Doppler frequency offset estimation method and system under high-speed rail environment
CN105656825A (en) * 2016-02-26 2016-06-08 北京交通大学 Doppler frequency shift correction method for rail transit high-speed mobile context

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8355473B2 (en) * 2009-04-19 2013-01-15 Qualcomm Incorporated Methods and systems with simplified doppler spread classification

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1588834A (en) * 2004-09-16 2005-03-02 北京天碁科技有限公司 Frequency deviation evaluation device and method
CN105007241A (en) * 2015-07-01 2015-10-28 杭州祥声通讯股份有限公司 Doppler frequency offset estimation method and system under high-speed rail environment
CN105656825A (en) * 2016-02-26 2016-06-08 北京交通大学 Doppler frequency shift correction method for rail transit high-speed mobile context

Also Published As

Publication number Publication date
CN106789773A (en) 2017-05-31

Similar Documents

Publication Publication Date Title
CN106789773B (en) Method and device for determining frequency offset and Doppler spread in high-speed mobile scene
US10219238B2 (en) OTDOA in LTE networks
US11095491B2 (en) Methods and apparatus for frequency offset estimation
CN101599939B (en) Method and device for estimating reference signal received power of orthogonal frequency division multiplexing system
US20110158361A1 (en) Radio channel analyzer to determine doppler shifts across multiple frequencies of a wideband signal
CN101577692A (en) Channel estimating method of orthogonal frequency division multiplexing system and device thereof
CN109672635B (en) Time domain correlation estimation method, device and equipment
CN113225274A (en) Multi-path channel model measuring method for fast moving
Hui et al. Efficient Doppler mitigation for high-speed rail communications
CN101635598A (en) Method and device for estimating noise power
CN109510672A (en) A kind of method for estimating time-varying channel parameter
Rodríguez-Piñeiro et al. Affordable evaluation of 5G modulation schemes in high speed train scenarios
Zhou et al. Ricean K-factor measurements and analysis for wideband radio channels in high-speed railway U-shape cutting scenarios
KR20050116010A (en) Velocity estimator in mobile communication system
WO2000069138A1 (en) Method and apparatus to determine the speed of mobile communications apparatus
CN102783108B (en) For the method and apparatus of estimating Doppler frequency
Rodríguez-Piñeiro et al. Experimental assessment of 5G-candidate modulation schemes at extreme speeds
Tang et al. An enhanced LMMSE channel estimation under high speed railway scenarios
Semmar et al. Digital broadcasting television channel measurements and characterization for SIMO mobile reception
Lerch et al. Methods to perform high velocity LTE experiments at low velocities
Cai et al. Time-variant Doppler frequency estimation and compensation for mobile OFDM systems
Zhao et al. Wireless Channel Measurements and Modeling of LTE Broadband System for High‐Speed Railway Scenarios
CN106850483B (en) Phase error estimation method and device for wireless communication system
EP3262803A1 (en) Communication device and method for joint offset estimation
Domínguez-Bolaño Design and evaluation of new waveforms for high mobility communications

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CP03 Change of name, title or address
CP03 Change of name, title or address

Address after: 100085 unit C, building C, lin66, Zhufang Road, Qinghe, Haidian District, Beijing

Patentee after: Beijing Xiaomi pinecone Electronic Co., Ltd

Address before: 100085 Beijing city Haidian District Qinghe Shun Yip things Park Building 3 unit A

Patentee before: BEIJING PINECONE ELECTRONICS Co.,Ltd.