CN106789773A - The determination method and device of frequency deviation and doppler spread under high-speed mobile scene - Google Patents

Abstract

This disclosure relates to the determination method and device of the frequency deviation and doppler spread under a kind of high-speed mobile scene, the method includes：Effective diameter is obtained according to channel impulse response and the effective diameter correlation of each effective diameter is obtained, the phase according to effective diameter correlation obtains the offset estimation of each effective diameter；Power calculation according to each effective diameter merges weight, and the offset estimation of each effective diameter is weighted into merging to merge weight, obtains weighted average offset estimation；According to the offset estimation of each effective diameter, weighted average offset estimation is estimated with weight, the frequency deviation extension of acquisition root mean square is merged as doppler spread.Can solve the problem that under High-speed Circumstance, the direct-view footpath composition of each bar multipath is larger and when carrying different frequency deviations, the inapplicable problem of conventional method effectively can be estimated frequency deviation；And homogenous diffusion model is invalid in can evading traditional Doppler estimation, the inapplicable problem of Bessel function can obtain the doppler spread under high-speed mobile scene.

Description

The determination method and device of frequency deviation and doppler spread under high-speed mobile scene

Technical field

This disclosure relates to frequency deviation and doppler spread under communication technical field, more particularly to a kind of high-speed mobile scene Determine method and device.

Background technology

Every multipath is made up of the footpath that can not differentiate of homogenous diffusion on normal channel, and the frequency deviation that each bar multipath is carried, It is mainly the frequency departure between network side sending signal frequency and terminal local crystal oscillator frequency.At present, adopted along high ferro Covered with private network, its cloth net mode is generally using BBU (English：Base Band Unit, Chinese：Base Band Unit) and RRU (English：Radio Remote Unit, Chinese：Wireless remote unit) mode that combines, therefore in the multiple of same base station The terminal of high-speed mobile between RRU, can simultaneously receive the angle between the wireless signal from multiple RRU, and terminal and each RRU It is different.Because the direct-view footpath composition of every multipath of high ferro channel is larger, scattering footpath composition is less, the frequency deviation that each bar multipath is carried It is relevant with the speed of terminal, and the factor such as terminal and the angle of each RRU, and the calculating offset estimation that prior art is used It is that each bar multipath carries same frequency deviation and channel meets Rayleigh fading in channel with the premise of the method for doppler spread, thus it is right It is no longer appropriate in the scene for being related to high-speed mobile.

The content of the invention

To overcome problems of the prior art, the disclosure to provide frequency deviation and Doppler under a kind of high-speed mobile scene The determination method and device of extension.

According to the first aspect of the embodiment of the present disclosure, there is provided frequency deviation and doppler spread under a kind of high-speed mobile scene Determine method, including：

Effective diameter is obtained according to channel impulse response；

Obtain the effective diameter correlation of each effective diameter, and according to the phase of the effective diameter correlation is obtained each The offset estimation of effective diameter；

Power calculation according to each effective diameter merges weight, by the offset estimation of each effective diameter with the merging Weight is weighted merging, obtains weighted average offset estimation；

According to the offset estimation of each effective diameter, the weighted average offset estimation and the merging weight are obtained The extension of root mean square frequency deviation is taken, is estimated as doppler spread.

Optionally, it is described that effective diameter is obtained according to channel impulse response, including：

Channel estimation in frequency domain is transformed into time domain, channel impulse response is obtained；

Obtain the power delay profile of each sampling point in the channel impulse response；

According to the power delay profile of each sampling point, power sequence is carried out；

The power of noise and interference is determined according to power sequence and maximum effective diameter bar number；

The peak power in the sequence of power and the power according to the noise and interference is determined for screening effectively The power threshold in footpath；

Sampling point using the power in described each sampling point more than the power threshold is used as effective diameter.

Optionally, the effective diameter correlation for obtaining each effective diameter, and according to the phase of the effective diameter correlation The offset estimation of each effective diameter is obtained, including：

Obtain the effective diameter correlation of each effective diameter；

Effective diameter correlation to each effective diameter carries out phase extraction, and according to the correlation of each effective diameter The phase that value is extracted obtains the offset estimation of each effective diameter.

Optionally, it is described that weight is merged according to the power calculation of each effective diameter, the frequency deviation of each effective diameter is estimated Meter is weighted merging with the merging weight, obtains weighted average offset estimation, including：

Obtain the power summation of the available signal power of each effective diameter；

Using the ratio of the available signal power of each effective diameter and the power summation of the available signal power as described The merging weight of each effective diameter；

The offset estimation of each effective diameter is weighted merging with the merging weight, the weighted average is obtained Offset estimation.

Optionally, it is described that channel estimation in frequency domain is transformed into time domain when orthogonal frequency division multiplex OFDM system is applied to, obtain To channel impulse response, including：

The channel estimation in frequency domain is converted by carrying out Fast Fourier Transform Inverse IFFT to the channel estimation in frequency domain To time domain, the channel impulse response is obtained；

The formula of the IFFT includes：

Wherein,Represent and be located at l-th CRS OFDM symbol on time orientation, k-th CRS RE in frequency direction Channel estimation in frequency domain；Represent the value of n-th sampling point of the channel impulse response of l-th CRS OFDM symbols, N_FFT The points of the IFFT are represented, the total sample of the channel estimation in frequency domain is equal to N_FFT, K represents CRS RE in frequency direction Sum, L represents the sum of CRS symbols on time orientation；

Wherein, when the IFFT is carried out, N is worked as_FFTDuring ＞ K, to the frequency domain channel in l-th CRS OFDM symbols Estimation carries out benefit 0, the length of the channel estimation in frequency domain in l-th CRS OFDM symbols is equal to the N_FFT；Work as N_FFT≤K When, take the N in the channel estimation in frequency domain in l-th CRS OFDM symbols_FFTIndividual sampling point carries out the IFFT.

Optionally, when ofdm system is applied to, the power of each sampling point in the acquisition channel impulse response Postpone distribution, including：

Power averaging is carried out to the channel impulse response that each CRS OFDM symbol is calculated and obtains the power-delay point Cloth PDP；

Wherein, the formula for carrying out the power averaging includes：

Wherein,N-th power of sampling point in the PDP is represented,Represent l-th CRS OFDM symbols The value of n-th sampling point of channel impulse response, N_FFTRepresent the points of the IFFT, the total sample of the channel impulse response Equal to N_FFT。

Optionally, when ofdm system is applied to, the power delay profile of each sampling point described in the basis carries out power Sequence, including：

By the power sequence in the power delay profileIt is ranked up according to power order from big to small, obtains institute Power sequence is stated, the power sequence includes new sequenceWherein

The power that noise and interference are determined according to power sequence and maximum effective diameter bar number, including：

Sorted according to the power, before prominent in described each sampling pointOther samples outside individual sampling point Point is defined as noise and interference sampling point；

According to noise and the acquisition noise and the power of interference of the rating formula of interference sampling point；

The computing formula of the power of the noise and interference sampling point includes：

Wherein,Represent the maximum effective diameter bar number, N_FFTThe points of the IFFT are represented, the channel impulse is rung The total sample answered is equal to N_FFT, σ²Represent the power of the noise and interference sampling point.

Optionally, it is described to be arranged according to the noise and the power and the power of interference when ofdm system is applied to Peak power in sequence determines the power threshold for screening effective diameter, including：

The peak power in the sequence of power and the power according to the noise and interference, is calculated using power threshold Formula determines the power threshold；

The power threshold computing formula, including：

Wherein, Γ represents the power threshold, ρ_noiseRepresent noise gate coefficient, σ²Represent the noise and interference sampling point Power, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in the power sequence.

Optionally, when ofdm system is applied to, the effective diameter correlation of each effective diameter of acquisition, including：

Using correlation value calculation formula, the effective diameter for calculating the same position in adjacent C RS OFDM symbols carries out effective diameter Correlation；

The correlation value calculation formula includes：

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS on time orientation The sampling point i of the channel impulse response of OFDM symbol_nValue,Represent the l+1 CRS OFDM symbol on time orientation The sampling point i of channel impulse response_nValue, wherein sampling point i_nIt is the sampling point as n-th effective diameter, N_pathRepresent effective diameter Quantity.

Optionally, when ofdm system is applied to, the effective diameter correlation to each effective diameter enters line phase Extract, and the offset estimation of each effective diameter is obtained according to the phase that the correlation of each effective diameter is extracted, including：

Phase extraction is carried out to the effective diameter correlation of each effective diameter using phase calculation formula；

The phase extracted using the correlation of frequency offset calculation formula each effective diameter according to obtains each effective diameter Offset estimation；

Wherein, the phase calculation formula includes：

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent the effective of n-th effective diameter Footpath correlation, N_pathRepresent the quantity of effective diameter；

The frequency offset calculation formula includes：

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RS OFDM symbols.

Optionally, when ofdm system is applied to, the power of the available signal power of each effective diameter described in the acquisition Summation, including：

For described each effective diameter：The value that the power of effective diameter is subtracted the power of noise and interference is compared with zero Compared with using the maximum in the two as the available signal power of effective diameter, obtaining the available signal power of each effective diameter；

Using power sum formula, the power summation of the available signal power of each effective diameter is obtained；

Wherein, the power sum formula includes：

Wherein,The power summation is represented,N-th power of effective diameter is represented,Represent described n-th it is effective The available signal power in footpath, σ²Represent the power of the noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

Optionally, when ofdm system is applied to, the offset estimation by each effective diameter merges power with described Merging is weighted again, obtains the weighted average offset estimation, including：

The offset estimation of each effective diameter is merged using weighted average frequency deviation formula, obtains the weighting flat Equal offset estimation；

Wherein, the weighted average frequency deviation formula, including：

Wherein, f_oThe weighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresent n-th The merging weight of the offset estimation of individual effective diameter,The power summation is represented,Represent the useful of n-th effective diameter Signal power.

Optionally, the offset estimation of each effective diameter described in the basis, the weighted average offset estimation and described Merge weight, obtain the extension of root mean square frequency deviation, estimate as doppler spread, including：

According to the offset estimation of each effective diameter, the weighted average offset estimation and each effective diameter Merge weight, obtaining the root mean square frequency deviation using root mean square extension computing formula extends；

Root mean square extension is estimated as the doppler spread；

Wherein, the root mean square extension computing formula includes：

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has Imitate the merging weight of the offset estimation in footpath, f_oRepresent the weighted average offset estimation, N_pathRepresent the quantity of effective diameter.

According to the second aspect of the embodiment of the present disclosure, there is provided a kind of determining device of the frequency deviation under high-speed mobile scene, institute Stating device includes：

Effective diameter acquisition module, for obtaining effective diameter according to channel impulse response；

Frequency deviation estimating modules, the effective diameter correlation for obtaining each effective diameter, and according to the effective diameter correlation Phase obtain the offset estimation of each effective diameter；

Weighted average frequency deviation estimating modules, for merging weight according to the power calculation of each effective diameter, will it is described each The offset estimation of effective diameter is weighted merging with the merging weight, obtains weighted average offset estimation；

Doppler spread estimation module, for the offset estimation according to each effective diameter, the weighted average frequency deviation Estimate and the merging weight, obtain the extension of root mean square frequency deviation, estimate as doppler spread.

Optionally, the effective diameter acquisition module, including：

Impulse response acquisition submodule, for channel estimation in frequency domain to be transformed into time domain, obtains channel impulse response；

Power delay profile acquisition submodule, the power-delay for obtaining each sampling point in the channel impulse response Distribution；

Power sorting sub-module, for the power delay profile according to each sampling point, carries out power sequence；

Noise and the power determination sub-module of interference, for being determined according to power sequence and maximum effective diameter bar number Noise and the power of interference；

Power threshold determination sub-module, for according to the noise and interference power and the power sequence in most High-power determination is used to screen the power threshold of effective diameter；

Effective diameter determination sub-module, for using the power in described each sampling point more than the power threshold sampling point as Effective diameter.

Optionally, the frequency deviation estimating modules, including：

Effective diameter correlation acquisition submodule, the effective diameter correlation for obtaining each effective diameter；

Offset estimation acquisition submodule, phase extraction is carried out for the effective diameter correlation to each effective diameter, and The phase that correlation according to each effective diameter is extracted obtains the offset estimation of each effective diameter.

Optionally, the weighted average frequency deviation estimating modules, including：

Power summation acquisition submodule, the power summation of the available signal power for obtaining each effective diameter；

Merge Weight Acquisition submodule, for by the available signal power of each effective diameter and the available signal power The ratio of power summation as each effective diameter merging weight；

Weighted average offset estimation submodule, for the offset estimation of each effective diameter to be entered with the merging weight Row weighting merges, and obtains the weighted average offset estimation.

Optionally, when ofdm system is applied to, the impulse response acquisition submodule is used for：

The channel estimation in frequency domain is converted by carrying out Fast Fourier Transform Inverse IFFT to the channel estimation in frequency domain To time domain, the channel impulse response is obtained；

The formula of the IFFT includes：

Wherein,Represent and be located at l-th CRS OFDM symbol on time orientation, k-th CRS RE in frequency direction Channel estimation in frequency domain；Represent the value of n-th sampling point of the channel impulse response of l-th CRS OFDM symbols, N_FFT The points of the IFFT are represented, the total sample of the channel impulse response is equal to N_FFT, K represents CRS RE in frequency direction Sum, L represents the sum of CRS symbols on time orientation；

Wherein, when the IFFT is carried out, N is worked as_FFTDuring ＞ K, to the frequency domain channel in l-th CRS OFDM symbols Estimation carries out benefit 0, the length of the channel estimation in frequency domain in l-th CRS OFDM symbols is equal to the N_FFT；Work as N_FFT≤K When, take the N in the channel estimation in frequency domain in l-th CRS OFDM symbols_FFTIndividual sampling point carries out the IFFT.

Optionally, when ofdm system is applied to, the power delay profile acquisition submodule is used for：

Power averaging is carried out to the channel impulse response that each CRS OFDM symbol is calculated and obtains the power-delay point Cloth PDP；

Wherein, the formula for carrying out the power averaging includes：

Wherein,N-th power of sampling point in the PDP is represented,Represent l-th CRS OFDM symbols The value of n-th sampling point of channel impulse response, N_FFTRepresent the points of the IFFT, the total sample of the channel impulse response Equal to N_FFT。

Optionally, when ofdm system is applied to, the power sorting sub-module is used for：

By the power sequence in the power delay profileIt is ranked up according to power order from big to small, obtains institute Power sequence is stated, the power sequence includes new sequenceWherein

The noise and the power determination sub-module of interference, including：

Noise and interference sampling point determination sub-module, for being sorted according to the power, by power in described each sampling point most Before bigOther sampling points outside individual sampling point are defined as noise and interference sampling point；

Noise and the power acquisition submodule of interference, for the acquisition according to noise and the rating formula of interference sampling point The noise and the power of interference；

The computing formula of the power of the noise and interference sampling point includes：

Wherein,Represent the maximum effective diameter bar number, N_FFTThe points of the IFFT are represented, the channel impulse is rung The total sample answered is equal to N_FFT, σ²Represent the power of the noise and interference sampling point.

Optionally, when ofdm system is applied to, the power threshold determination sub-module is used for：

The peak power in the sequence of power and the power according to the noise and interference, is calculated using power threshold Formula determines the power threshold；

The power threshold computing formula, including：

Wherein, Γ represents the power threshold, ρ_noiseRepresent noise gate coefficient, σ²Represent the noise and interference sampling point Power, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in the power sequence.

Optionally, when ofdm system is applied to, the effective diameter correlation acquisition submodule is used for：

Using correlation value calculation formula, the effective diameter for calculating the same position in adjacent C RS OFDM symbols carries out effective diameter Correlation；

The correlation value calculation formula includes：

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS on time orientation The sampling point i of the channel impulse response of OFDM symbol_nValue,Represent the l+1 CRS OFDM symbol on time orientation The sampling point i of channel impulse response_nValue, wherein sampling point i_nIt is the sampling point as n-th effective diameter, N_pathRepresent effective diameter Quantity.

Optionally, when ofdm system is applied to, the offset estimation acquisition submodule, including：

Phase extraction submodule, for being carried out to the effective diameter correlation of each effective diameter using phase calculation formula Phase extraction；

Offset estimation determination sub-module, extracts for the correlation using frequency offset calculation formula each effective diameter according to Phase obtain the offset estimation of each effective diameter；

Wherein, the phase calculation formula includes：

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent the effective of n-th effective diameter Footpath correlation, N_pathRepresent the quantity of effective diameter；

The frequency offset calculation formula includes：

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RS OFDM symbols.

Optionally, when ofdm system is applied to, the power summation acquisition submodule, including：

Available signal power acquisition submodule, for for described each effective diameter：The power of effective diameter is subtracted into noise Value with the power of interference is compared with zero, using the maximum in the two as the available signal power of effective diameter, obtains institute State the available signal power of each effective diameter；

Power summation determination sub-module, for utilizing power sum formula, obtains the useful signal of each effective diameter The power summation of power；

Wherein, the power sum formula includes：

Wherein,The power summation is represented,N-th power of effective diameter is represented,Represent described n-th it is effective The available signal power in footpath, σ²Represent the power of the noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

Optionally, when ofdm system is applied to, the weighted average offset estimation submodule is used for：

The offset estimation of each effective diameter is merged using weighted average frequency deviation formula, obtains the weighting flat Equal offset estimation；

Wherein, the weighted average frequency deviation formula, including：

Wherein, f_oThe weighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresent n-th The merging weight of the offset estimation of individual effective diameter,The power summation is represented,Represent the useful of n-th effective diameter Signal power.

Optionally, the doppler spread estimation module, including：

Root mean square frequency deviation extends acquisition submodule, and for the offset estimation according to each effective diameter, the weighting is put down The merging weight of equal offset estimation and each effective diameter, the root mean square is obtained frequently using root mean square extension computing formula Extension partially；

Doppler spread estimates submodule, for root mean square extension to be estimated as the doppler spread；

Wherein, the root mean square extension computing formula includes：

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has Imitate the merging weight of the offset estimation in footpath, f_oRepresent the weighted average offset estimation, N_pathRepresent the quantity of effective diameter.

The technical scheme provided by this disclosed embodiment can include the following benefits：

Effective diameter is obtained by according to channel impulse response；The effective diameter correlation of each effective diameter is obtained, and according to institute The phase for stating effective diameter correlation obtains the offset estimation of each effective diameter；Power calculation according to each effective diameter merges Weight, merging is weighted by the offset estimation of each effective diameter with the merging weight, is obtained weighted average frequency deviation and is estimated Meter；According to the offset estimation of each effective diameter, the weighted average offset estimation and the merging weight are obtained square Root frequency deviation extends, and estimates as doppler spread.Can solve the problem that under High-speed Circumstance, the direct-view footpath composition of each bar multipath is larger, And when carrying different frequency deviations, the no longer applicable problem of conventional offset estimation, frequency deviation that can be effectively to channel is estimated. Also, it is further, can be calculated according to the power summation of the available signal power of each effective diameter and available signal power The weight of each effective diameter, and weighted average offset estimation, the root mean square extension for obtaining each effective diameter are expanded as Doppler Exhibition, homogenous diffusion model is invalid in can evading traditional Doppler estimation, the inapplicable problem of Bessel function, so that The doppler spread under high-speed mobile scene can be obtained.

Other feature and advantage of the disclosure will be described in detail in subsequent specific embodiment part.

Brief description of the drawings

Accompanying drawing is, for providing further understanding of the disclosure, and to constitute the part of specification, with following tool Body implementation method is used to explain the disclosure together, but does not constitute limitation of this disclosure.In the accompanying drawings：

Fig. 1 be frequency deviation and doppler spread under a kind of high-speed mobile scene according to an exemplary embodiment really Determine the flow chart of method；

Fig. 2 is a kind of flow chart of the acquisition methods of the effective diameter according to embodiment illustrated in fig. 1；

Fig. 3 is a kind of flow chart of the determination method of the offset estimation of the effective diameter according to embodiment illustrated in fig. 1；

Fig. 4 is a kind of flow chart of the determination method of the weighted average offset estimation according to embodiment illustrated in fig. 1；

Fig. 5 is the flow chart of a kind of noise according to embodiment illustrated in fig. 2 and the power determining method of interference；

Fig. 6 is a kind of acquisition of the power summation of the available signal power of the effective diameter according to embodiment illustrated in fig. 2 The flow chart of method；

Fig. 7 is the flow chart of the determination method that a kind of doppler spread according to embodiment illustrated in fig. 1 is estimated；

Fig. 8 be frequency deviation and doppler spread under a kind of high-speed mobile scene according to an exemplary embodiment really Determine the block diagram of device；

Fig. 9 is a kind of block diagram of the effective diameter acquisition module according to embodiment illustrated in fig. 8；

Figure 10 is a kind of block diagram of the frequency deviation estimating modules according to embodiment illustrated in fig. 8；

Figure 11 is a kind of block diagram of the weighted average frequency deviation estimating modules according to embodiment illustrated in fig. 8；

Figure 12 is the block diagram of a kind of noise according to embodiment illustrated in fig. 9 and the power determination sub-module of interference；

Figure 13 is a kind of block diagram of the offset estimation acquisition submodule according to embodiment illustrated in fig. 10；

Figure 14 is a kind of block diagram of the power summation acquisition submodule according to embodiment illustrated in fig. 11；

Figure 15 is a kind of block diagram of the doppler spread estimation module according to embodiment illustrated in fig. 8.

Specific embodiment

It is described in detail below in conjunction with accompanying drawing specific embodiment of this disclosure.It should be appreciated that this place is retouched The specific embodiment stated is merely to illustrate and explains the disclosure, is not limited to the disclosure.

Before specific embodiment is introduced, it is necessary first to which the relevant noun to being related in the disclosure is illustrated.Frequency deviation：Just It is the amplitude of FM wave frequency swing, the frequency typically referred between network side sending signal and terminal local crystal oscillator frequency is inclined Difference, accurate offset estimation can ensure OFDM (English：Orthogonal Frequency Division Multiplexing, Chinese：OFDM) AFC (English in system：Auto Frequency Control, Chinese： Automatic frequency is controlled) steady operation, aforementioned frequencies deviation is approximately zero, the ICI (English in reduction system：Inter- Carrier Interference, Chinese：Inter-carrier interference).

Doppler phenomenon is the spectral emissions phenomenon caused by translational speed, when transmitting terminal and receiving terminal make relative motion When, the signal frequency of receiving terminal can shift, and Doppler frequency shift is generally called doppler spread, and it represents declining for channel Terminal-velocity rate.The influence that docking is collected mail number can regard the doppler spread or video stretching of emission signal frequency as rather than regarding one as Frequency deviation, maximum doppler frequency is a measured value of Doppler frequency spectrum broadening, is the one kind to the time-varying characteristics of wireless channel Measurement.For the terminal of wireless communication system, doppler spread shows as, and moving velocity of terminal is faster, and it receives signal The channel for being experienced change within the unit interval (decline) it is faster, receipt signal frequency spectrum diverging it is more serious.In wireless channel most Doppler spreads f_maxBy translational speed v and carrier frequency f_cTogether decide on, i.e. f_max=vf_c/c₀.Wherein, c₀Represent light Speed.Accurate doppler spread estimates that important references can be provided for the channel estimation in system, it is ensured that channel estimating performance, enters And lift downlink reception link performance.

Covered using private network along high ferro, its cloth net mode is generally by the way of BBU+RRU, that is to say, that every Individual base station is made up of a BBU and multiple RRU, so can effectively expand the coverage of each base station, reduces base station number, Reduction is arranged net cost.But the terminal of the high-speed mobile between multiple RRU of same base station, meeting can be caused with this cloth net mode The wireless signal from multiple RRU is received simultaneously, and because the angle between terminal and each RRU is different, causes institute on each bar footpath The Doppler frequency shift of carrying is different.Therefore when the Doppler frequency shift on each bar footpath is different, will cause to receive the frequency spectrum of signal Diverging forms doppler spread.

At present, for normal channel offset estimation and doppler spread be mainly based upon it is two neighboring on time orientation CRS (English：Cell-Specific Reference Signals, Chinese：Cell-specific pilot signal) symbol estimation Correlation is calculated, and can preferably be worked under most of scene using the method.But under high-speed mobile scene, such as Above-mentioned high ferro scene, its performance occurs a certain degree of decline, because the direct-view footpath of every multipath of high ferro channel Composition is larger, and scattering footpath composition is less；Frequency deviation and the speed of terminal that each bar multipath is carried, and terminal and each RRU angle Relevant etc. factor, the offset estimation and the premise of doppler spread application that prior art is used are that each bar multipath is taken in channel With same frequency deviation and channel meets Rayleigh fading, the scene for being related to high-speed mobile is no longer appropriate for.

Additionally, the fast development that China in Recent Years high ferro is built, according to Chinese mid-long term railway network plan scheme, the year two thousand twenty High-speed railway mileage of the Chinese speed per hour more than 200 kilometers will more than 30000 kilometers, therefore how high speed advance train The upper very fast 4G services of experience turn into problem demanding prompt solution.

Fig. 1 be frequency deviation and doppler spread under a kind of high-speed mobile scene according to an exemplary embodiment really The flow chart of method is determined, as shown in figure 1, the method is comprised the following steps：

Step 101, effective diameter is obtained according to channel impulse response.

Wherein, the acquisition modes of the effective diameter that the disclosure is used, will describe in detail in the embodiment of Fig. 2 below.

Step 102, obtains the effective diameter correlation of each effective diameter, and obtains each according to the phase of effective diameter correlation The offset estimation of effective diameter.

According to the effective diameter obtained in step 101, step 102 is then the frequency deviation for the offset estimation of above-mentioned effective diameter Estimate that the estimation for effective diameter correlation and the phase of effective diameter correlation should be included.The Fig. 3 of specific embodiment after Embodiment in describe in detail.

Step 103, power calculation according to each effective diameter merges weight, by the offset estimation of each effective diameter merging Weight is weighted merging, obtains weighted average offset estimation.

The mode of weighted average offset estimation will be described in detail in the fig. 4 embodiment.

Step 104, according to the offset estimation of each effective diameter, weighted average offset estimation and merges weight, obtains equal Root frequency deviation extends, and estimates as doppler spread.

Wherein, because the method for calculating doppler spread by Bessel function in conventional art is only applicable to homogenous diffusion Model, therefore under the high-speed mobile scene involved by the present embodiment, for invalid, Bezier of evading homogenous diffusion model The inapplicable problem of function, can obtain doppler spread by obtaining the root mean square extension of each effective diameter, and its is specific Implementation method is illustrated in greater detail below.

In sum, the determination method of frequency deviation and doppler spread under the high-speed mobile scene that the disclosure is provided, energy It is enough that effective diameter is obtained according to channel impulse response and the effective diameter correlation of each effective diameter is obtained and related according to effective diameter The phase of value obtains the offset estimation of each effective diameter；Power calculation further according to each effective diameter merges weight, and each is had The offset estimation for imitating footpath is weighted merging to merge weight, obtains weighted average offset estimation；Afterwards according to each effective diameter Offset estimation, weighted average offset estimation and merge weight, obtain the extension of root mean square frequency deviation, estimate as doppler spread Meter.When can solve the problem that under High-speed Circumstance, the direct-view footpath composition of each bar multipath is larger, and carrying different frequency deviations, conventional frequency deviation Estimate no longer applicable problem, frequency deviation that can be effectively to channel is estimated.Also, it is further, can be according to each The available signal power of effective diameter and the power summation of available signal power calculate the weight of each effective diameter and weighting is put down Equal offset estimation, the root mean square for obtaining each effective diameter is extended as doppler spread, can evade traditional Doppler estimation side Homogenous diffusion model is invalid in method, the inapplicable problem of Bessel function, many under high-speed mobile scene such that it is able to obtain Doppler spread.

Illustratively, Fig. 2 is a kind of flow chart of the acquisition methods of the effective diameter according to embodiment illustrated in fig. 1, such as Fig. 2 It is shown, effective diameter is obtained according to channel impulse response described in the step 101 in above-mentioned Fig. 1, comprise the following steps：

Step 1011, time domain is transformed to by channel estimation in frequency domain, obtains channel impulse response (English：Channel Impulse Response, referred to as：CIR).

Wherein, wherein channel impulse response is time domain channel estimation, by channel estimation from frequency-domain transform to time domain, can be adopted With inverse Fourier transform or inverse fast Fourier transform (English：Inverse Fast Fourier Transformation, Referred to as：IFFT), power delay profile (English is obtained in step 1012 being carried out after the CIR under obtaining time domain：Power Delay Profile, referred to as：PDP operation).

Illustratively, when ofdm system is applied to, frequency domain channel can be estimated by carrying out IFFT to channel estimation in frequency domain Meter transforms to time domain, obtains channel impulse response.

Wherein, the formula of the IFFT includes：

Wherein,Represent and be located at l-th CRS OFDM symbol, k-th CRS RE in frequency direction on time orientation (English：Resource Element, Chinese：Resource particle) channel estimation in frequency domain；Represent l-th CRS OFDM symbol Number channel impulse response n-th sampling point value, N_FFTThe points of IFFT are represented, the total sample of channel impulse response is equal to N_FFT, K represents the sum of CRS RE in frequency direction, and L represents the sum of CRS symbols on time orientation.

, wherein it is desired to explanation, when IFFT is carried out, works as N_FFTDuring ＞ K, to the frequency domain in l-th CRS OFDM symbol Channel estimation carries out benefit 0, the length of the channel estimation in frequency domain in l-th CRS OFDM symbol is equal to N_FFT；Work as N_FFTDuring≤K, Take the N in the channel estimation in frequency domain in l-th CRS OFDM symbol_FFTIndividual sampling point carries out IFFT.

Illustratively, when channel width is 10M, K values are 100, can set N_FFTIt is 128, now N_FFT＞ K, then need To the channel estimation in frequency domain in l-th CRS OFDM symbol mend 0 operation, so as to the frequency in l-th CRS OFDM symbol The length of domain channel estimation is equal to 128.

Step 1012, obtains the power delay profile of each sampling point in channel impulse response.

Illustratively, when ofdm system is applied to, the step includes：The channel punching calculated each CRS OFDM symbol Sharp response carries out power averaging and obtains PDP.

Wherein, the formula for carrying out power averaging includes：

Wherein,N-th power of sampling point in PDP is represented,Represent l-th channel impulse of CRS OFDM symbols The value of n-th sampling point of response, N_FFTThe points of IFFT are represented, the total sample of channel impulse response is equal to N_FFT。

Step 1013, according to the power delay profile of each sampling point, carries out power sequence.

Illustratively, when ofdm system is applied to, the step includes：By the power sequence in power delay profileAccording to Power order from big to small is ranked up, and obtains power sequence, and power sequence includes new sequenceWherein

After having got all sampling points of PDP by carrying out the formula of power averaging in step 1012, according to being calculated 'sValue, is ranked up to it, the power of each sampling point can be ranked up according to power descending order, after sequence Result can be expressed as：Wherein i_nIt is the sequence index after sequence.

Step 1014, the power of noise and interference is determined according to power sequence and maximum effective diameter bar number.

Wherein, the size of noise and the power of interference is associated with several factors, can be accomplished in several ways, according to The mode that different application scenario selections are adapted to, in the present embodiment can according in power sequence and maximum effective diameter bar number come Determine the power of noise and interference, wherein maximum effective diameter bar number pre-sets, its specific numerical value can be according to bandwidth To determine.

Step 1015, the peak power in the sequence of power and power according to noise and interference is determined for screening effectively The power threshold in footpath.

Illustratively, when ofdm system is applied to, the step can be according to noise and power and the power sequence of interference In peak power, determine power threshold using power threshold computing formula, the power threshold computing formula, including：

Wherein, Γ represents power threshold, ρ_noiseRepresent noise gate coefficient, σ²The power of noise and interference sampling point is represented, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in power sequence.

Wherein, ρ_noiseAnd ρ_maxPathCan also be determined according to bandwidth, such as a width of 10M of the band of channel, ρ_noiseCan To be set to 3, and ρ_maxPathCould be arranged to 1/64.

Step 1016, the sampling point using the power in each sampling point more than power threshold is used as effective diameter.

It is after power threshold is determined in step 1015, power in all sampling points is true more than the sampling point of the power threshold It is set to effective diameter, and records the quantity of effective diameter, the quantity of effective diameter can uses N_pathRepresent.Example, it is assumed that described each Number of samples in individual sampling point more than the power threshold is 6, and this 6 sampling points are just as effective diameter, and N_pathIt is equal to 6.

Illustratively, Fig. 3 is a kind of stream of the determination method of the offset estimation of the effective diameter according to embodiment illustrated in fig. 1 Cheng Tu, as shown in figure 3, the effective diameter correlation of acquisition each effective diameter described in step 102 in above-mentioned Fig. 1, and according to having The phase for imitating footpath correlation obtains the offset estimation of each effective diameter, comprises the following steps：

Step 1021, obtains the effective diameter correlation of each effective diameter.

The correlation of wherein each effective diameter can be understood as two adjacent CRSs of the effective diameter on time orientation OFDM (English：Orthogonal Frequency Division Multiplexing, Chinese：Orthogonal frequency division multiplexi) symbol Number channel impulse response correlation, its specific embodiment illustrates in greater detail below.

Illustratively, it is possible to use correlation value calculation formula, the same position in calculating adjacent C RS OFDM symbols is effective Footpath carries out effective diameter correlation, and wherein correlation value calculation formula includes：

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS on time orientation The sampling point i of the channel impulse response of OFDM symbol_nValue,Represent the l+1 CRS OFDM symbol on time orientation The sampling point i of channel impulse response_nValue, wherein sampling point i_nIt is as n-th sampling point of effective diameter, N_pathRepresent the number of effective diameter Amount.

Step 1022, the effective diameter correlation to each effective diameter carries out phase extraction, and according to the phase of each effective diameter The phase that pass value is extracted obtains the offset estimation of each effective diameter.

Illustratively, when ofdm system is applied to, can be first with phase calculation formula to the effective of each effective diameter Footpath correlation carries out phase extraction.The phase calculation formula includes：

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent the effective of n-th effective diameter Footpath correlation, N_pathRepresent the quantity of effective diameter.

Frequency offset calculation formula is recycled to obtain each effective diameter according to the phase that the correlation of each effective diameter is extracted afterwards Offset estimation, the frequency offset calculation formula includes：

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RS OFDM symbols.

Illustratively, Fig. 4 is a kind of stream of the determination method of the weighted average offset estimation according to embodiment illustrated in fig. 1 Cheng Tu, as shown in figure 4, weight is merged according to the power calculation of each effective diameter described in step 103 in above-mentioned Fig. 1, will be each The offset estimation of individual effective diameter is weighted merging to merge weight, obtains weighted average offset estimation, comprises the following steps：

Step 1031, obtains the power summation of the available signal power of each effective diameter.

Wherein, the available signal power of each effective diameter can be above-mentioned by the way that the power of each effective diameter is individually subtracted Noise and jamming power, and each result is compared with 0 respectively, choose useful signal of the greater therein as the effective diameter Power.

Step 1032, using the ratio of the available signal power of each effective diameter and the power summation of available signal power as The merging weight of each effective diameter.

Step 1033, merging is weighted by the offset estimation of each effective diameter to merge weight, obtains weighted average frequently Estimate partially.

Above-mentioned steps can be understood as the power that the available signal power of each effective diameter is obtained in step 1032 Proportion and then is estimated according to the weight of each effective diameter as the weight of the effective diameter to the frequency deviation of each effective diameter in summation Meter is weighted averagely, so as to obtain the weighted average offset estimation.

Optionally, when ofdm system is applied to, the step can include：By the available signal power of each effective diameter with The ratio of the power summation of available signal power has using weighted average frequency deviation formula as the weight of each effective diameter to each The offset estimation for imitating footpath is merged, and obtains weighted average offset estimation.Wherein, the weighted average frequency deviation formula includes：

Wherein, f_oWeighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has The weight of the offset estimation in footpath is imitated,Power summation is represented,Represent n-th available signal power of effective diameter.

Example, Fig. 5 is the stream of a kind of noise according to embodiment illustrated in fig. 2 and the power determining method of interference Cheng Tu, as shown in figure 5, determining noise with interference according to power sequence and maximum effective diameter bar number described in above-mentioned steps 1014 Power, comprises the following steps：

Step 10141, sorts, before prominent in each sampling point according to powerOther outside individual sampling point Sampling point is defined as noise and interference sampling point.

Step 10142, according to noise and the power for obtaining noise and interference of the rating formula of interference sampling point.Its In, the computing formula of the power of the noise and interference sampling point includes：

Wherein,Represent maximum effective diameter bar number, N_FFTRepresent the points of IFFT, the total sample of channel impulse response Equal to N_FFT, represent σ in power sequence²Represent the power of noise and interference sampling point.

That is except before prominent in each above-mentioned sampling pointOutside individual sampling point, remaining sampling pointNoise and interference sampling point are can be regarded as, and noise and interference sample can be carried out using these sampling points The power σ of point²Calculating,Value can be determined according to bandwidth, such as the band of channel a width of 10M (million),May be configured as 8.

Illustratively, Fig. 6 is a kind of power summation of the available signal power of the effective diameter according to embodiment illustrated in fig. 2 Acquisition methods flow chart, as shown in fig. 6, when ofdm system is applied to, acquisition described in the step 1031 in Fig. 3 each The power summation of the available signal power of effective diameter, comprises the following steps：

Step 10311, for each effective diameter：The value that the power of effective diameter is subtracted the power of noise and interference is entered with zero Row compares, and using the maximum in the two as the available signal power of effective diameter, obtains the available signal power of each effective diameter.

That is, for the power after the power in the power of each effective diameter except denoising with interference, if greatly In zero, then the power after the power of denoising and interference as the available signal power of the effective diameter will be removed, if less than zero, Then using zero as the effective diameter available signal power, so it can be appreciated that garbage signal power is filtered.

Step 10312, using power sum formula, obtains the power summation of the available signal power of each effective diameter.Should Power sum formula includes：

Wherein,Power summation is represented,N-th power of effective diameter is represented,Represent the useful of n-th effective diameter Signal power, σ²Represent the power of noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

Illustratively, Fig. 7 is the flow of the determination method that a kind of doppler spread according to embodiment illustrated in fig. 1 is estimated Figure, as shown in fig. 7, when ofdm system is applied to, the offset estimation according to each effective diameter described in the step 104 in Fig. 1, Weighted average offset estimation and merge weight, obtain the extension of root mean square frequency deviation, estimate as doppler spread, can include with Lower step：

Step 1041, according to the offset estimation of each effective diameter, the conjunction of weighted average offset estimation and each effective diameter And weight, obtain root mean square frequency deviation using root mean square extension computing formula and extend.

Wherein, root mean square extension computing formula includes：

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has Imitate the merging weight of the offset estimation in footpath, f_oRepresent weighted average offset estimation, N_pathRepresent the quantity of effective diameter.

Step 1042, root mean square extension is estimated as doppler spread.

Using the calculation of above-mentioned root mean square, go for the condition that channel is unsatisfactory for Rayleigh fading, that is, be unsatisfactory for Channel is the scene of the model of homogenous diffusion, therefore the calculation is suitably applied in the Doppler of high-speed mobile scene lower channel The calculating of extension.

As can be seen here, the disclosure can solve the problem that the direct-view footpath composition of each bar multipath under High-speed Circumstance is larger, and carry not The no longer applicable problem of conventional frequency deviation estimating method caused by same frequency deviation, the frequency deviation that can be obtained under high-speed mobile scene is estimated Meter, and it is possible to evading, homogenous diffusion model in traditional Doppler estimation is invalid, Bessel function is inapplicable to ask Topic, may thereby determine that the doppler spread under high-speed mobile scene.

Fig. 8 be frequency deviation and doppler spread under a kind of high-speed mobile scene according to an exemplary embodiment really The block diagram of device is determined, as shown in figure 8, the device 800 includes：

Effective diameter acquisition module 810, for obtaining effective diameter according to channel impulse response.

Frequency deviation estimating modules 820, the effective diameter correlation for obtaining each effective diameter, and according to effective diameter correlation Phase obtains the offset estimation of each effective diameter.

Weighted average frequency deviation estimating modules 830, for merging weight according to the power calculation of each effective diameter, each are had The offset estimation for imitating footpath is weighted merging to merge weight, obtains weighted average offset estimation.

Doppler spread estimation module 840, for the offset estimation according to each effective diameter, weighted average offset estimation with And merge weight, and the extension of root mean square frequency deviation is obtained, estimate as doppler spread.

Optionally, Fig. 9 is a kind of block diagram of the effective diameter acquisition module shown in embodiment illustrated in fig. 8, as shown in figure 9, should Effective diameter acquisition module 810, including：

Impulse response acquisition submodule 811, for channel estimation in frequency domain to be transformed into time domain, obtains channel impulse response.

Power delay profile acquisition submodule 812, the power-delay for obtaining each sampling point in channel impulse response Distribution.

Power sorting sub-module 813, for the power delay profile according to each sampling point, carries out power sequence.

Noise and the power determination sub-module 814 of interference, for being determined according to power sequence and maximum effective diameter bar number Noise and the power of interference.

Power threshold determination sub-module 815, for the maximum work in power and the power sequence according to noise and interference Rate determines the power threshold for screening effective diameter.

Effective diameter determination sub-module 816, for the sampling point using the power in each sampling point more than power threshold as effective Footpath.

Optionally, Figure 10 is a kind of block diagram of the frequency deviation estimating modules according to embodiment illustrated in fig. 8, such as Figure 10 institutes Show, the frequency deviation estimating modules 820, including：

Effective diameter correlation acquisition submodule 821, the effective diameter correlation for obtaining each effective diameter.

Offset estimation acquisition submodule 822, phase extraction, and root are carried out for the effective diameter correlation to each effective diameter The phase extracted according to the correlation of each effective diameter obtains the offset estimation of each effective diameter.

Optionally, Figure 11 is a kind of block diagram of the weighted average frequency deviation estimating modules according to embodiment illustrated in fig. 8, such as Shown in Figure 11, the weighted average frequency deviation estimating modules 830, including：

Power summation acquisition submodule 831, the power summation of the available signal power for obtaining each effective diameter.

Merge Weight Acquisition submodule 832, for by the available signal power of each effective diameter and available signal power The ratio of power summation as each effective diameter merging weight.

Weighted average offset estimation submodule 833, for the offset estimation of each effective diameter to be added with merging weight Power merges, and obtains weighted average offset estimation.

Optionally, when ofdm system is applied to, impulse response acquisition submodule 811 is used for：

Channel estimation in frequency domain is transformed into time domain by carrying out Fast Fourier Transform Inverse IFFT to channel estimation in frequency domain, is obtained To channel impulse response；

The formula of IFFT includes：

Wherein,Represent and be located at l-th CRS OFDM symbol on time orientation, k-th CRS RE in frequency direction Channel estimation in frequency domain；Represent l-th value of n-th sampling point of the channel impulse response of CRS OFDM symbols, N_FFTRepresent The points of IFFT, the total sample of channel impulse response is equal to N_FFT, K represents the sum of CRS RE in frequency direction, when L is represented Between on direction CRS symbols sum；

Wherein, when IFFT is carried out, N is worked as_FFTDuring ＞ K, the channel estimation in frequency domain in l-th CRS OFDM symbol is carried out 0 is mended, the length of the channel estimation in frequency domain in l-th CRS OFDM symbol is equal to N_FFT；Work as N_FFTDuring≤K, l-th CRS is taken The N in channel estimation in frequency domain in OFDM symbol_FFTIndividual sampling point carries out IFFT.

Optionally, when ofdm system is applied to, power delay profile acquisition submodule 812 is used for：

Power averaging is carried out to the channel impulse response that each CRS OFDM symbol is calculated and obtains power delay profile PDP；

Wherein, the formula for carrying out power averaging includes：

Wherein,N-th power of sampling point in PDP is represented,Represent l-th channel impulse of CRS OFDM symbols The value of n-th sampling point of response, N_FFTThe points of IFFT are represented, the total sample of channel impulse response is equal to N_FFT。

Optionally, when ofdm system is applied to, power sorting sub-module 813 is used for：

By the power sequence in power delay profileIt is ranked up according to power order from big to small, obtains power row Sequence, power sequence includes new sequenceWherein

Optionally, Figure 12 is the power determination sub-module of a kind of noise according to embodiment illustrated in fig. 9 and interference Block diagram, as shown in figure 12, the power determination sub-module 814 of the noise and interference, including：

Noise and interference sampling point determination sub-module 8141, for being sorted according to power, will be prominent in each sampling point BeforeOther sampling points outside individual sampling point are defined as noise and interference sampling point.

Noise and the power acquisition submodule 8142 of interference, for the rating formula according to noise and interference sampling point Obtain the power of noise and interference.

The computing formula of the power of noise and interference sampling point includes：

Wherein,Represent maximum effective diameter bar number, N_FFTRepresent the points of IFFT, the total sample of channel impulse response Equal to N_FFT, σ²Represent the power of noise and interference sampling point.

Optionally, when ofdm system is applied to, power threshold determination sub-module 815 is used for：

The peak power in the sequence of power and power according to noise and interference, is determined using power threshold computing formula Power threshold.

The power threshold computing formula, including：

Wherein, Γ represents power threshold, ρ_noiseRepresent noise gate coefficient, σ²The power of noise and interference sampling point is represented, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in power sequence.

Optionally, when ofdm system is applied to, effective diameter correlation acquisition submodule 821 is used for：

Using correlation value calculation formula, the effective diameter for calculating the same position in adjacent C RS OFDM symbols carries out effective diameter Correlation；Correlation value calculation formula includes：

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS on time orientation The sampling point i of the channel impulse response of OFDM symbol_nValue,Represent the l+1 CRS OFDM symbol on time orientation The sampling point i of channel impulse response_nValue, wherein sampling point i_nIt is as n-th sampling point of effective diameter, N_pathRepresent the number of effective diameter Amount.

Optionally, Figure 13 is a kind of block diagram of the offset estimation acquisition submodule according to embodiment illustrated in fig. 10, such as Shown in Figure 13, when ofdm system is applied to, the offset estimation acquisition submodule 822, including：

Phase extraction submodule 8221, for being carried out to the effective diameter correlation of each effective diameter using phase calculation formula Phase extraction.

Offset estimation determination sub-module 8222, for being extracted according to the correlation of each effective diameter using frequency offset calculation formula Phase obtain the offset estimation of each effective diameter.

Wherein, phase calculation formula includes：

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent the effective of n-th effective diameter Footpath correlation, N_pathRepresent the quantity of effective diameter.

Frequency offset calculation formula includes：

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RS OFDM symbols.

Optionally, Figure 14 is a kind of block diagram of the power summation acquisition submodule according to embodiment illustrated in fig. 11, such as Shown in Figure 14, when ofdm system is applied to, power summation acquisition submodule 831, including：

Available signal power acquisition submodule 8311, for for each effective diameter：The power of effective diameter is subtracted into noise Value with the power of interference is compared with zero, using the maximum in the two as the available signal power of effective diameter, obtains each The available signal power of individual effective diameter.

Power summation determination sub-module 8312, for utilizing power sum formula, obtains the useful signal of each effective diameter The power summation of power.

Wherein, power sum formula includes：

Wherein,Power summation is represented,N-th power of effective diameter is represented,Represent the useful of n-th effective diameter Signal power, σ²Represent the power of noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

Optionally, when ofdm system is applied to, weighted average offset estimation submodule 833 is used for：

The offset estimation of each effective diameter is merged using weighted average frequency deviation formula, is obtained weighted average frequency deviation and is estimated Meter；

Wherein, weighted average frequency deviation formula, including：

Wherein, f_oWeighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has The merging weight of the offset estimation in footpath is imitated,Power summation is represented,Represent n-th available signal power of effective diameter.

Optionally, Figure 15 is a kind of block diagram of the doppler spread estimation module according to embodiment illustrated in fig. 8, is such as schemed Shown in 15, the doppler spread estimation module 840, including：

Root mean square frequency deviation extends acquisition submodule 841, for the offset estimation according to each effective diameter, weighted average frequency deviation Estimation and the merging weight of each effective diameter, obtain root mean square frequency deviation and extend using root mean square extension computing formula.

Doppler spread estimates submodule 842, for root mean square extension to be estimated as doppler spread.

Wherein, root mean square extension computing formula includes：

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has Imitate the merging weight of the offset estimation in footpath, f_oRepresent weighted average offset estimation, N_pathRepresent the quantity of effective diameter.

In sum, the disclosure can solve the problem that the direct-view footpath composition of each bar multipath under High-speed Circumstance is larger, and carry not The no longer applicable problem of conventional frequency deviation estimating method caused by same frequency deviation, the frequency deviation that can be obtained under high-speed mobile scene is estimated Meter, and it is possible to evading, homogenous diffusion model in traditional Doppler estimation is invalid, Bessel function is inapplicable to ask Topic, may thereby determine that the doppler spread under high-speed mobile scene.

Describe the preferred embodiment of the disclosure in detail above in association with accompanying drawing, but, the disclosure is not limited to above-mentioned reality The detail in mode is applied, in the range of the technology design of the disclosure, various letters can be carried out with technical scheme of this disclosure Monotropic type, these simple variants belong to the protection domain of the disclosure.

It is further to note that each particular technique feature described in above-mentioned specific embodiment, in not lance In the case of shield, can be combined by any suitable means.In order to avoid unnecessary repetition, the disclosure to it is various can The combination of energy is no longer separately illustrated.

Additionally, can also be combined between a variety of implementation methods of the disclosure, as long as it is without prejudice to originally Disclosed thought, it should equally be considered as disclosure disclosure of that.

Claims (26)

1. frequency deviation and the determination method of doppler spread under a kind of high-speed mobile scene, it is characterised in that methods described includes：

Effective diameter is obtained according to channel impulse response；

The effective diameter correlation of each effective diameter is obtained, and each is effective according to the phase of the effective diameter correlation is obtained The offset estimation in footpath；

Power calculation according to each effective diameter merges weight, by the offset estimation of each effective diameter with the merging weight Merging is weighted, weighted average offset estimation is obtained；

According to the offset estimation of each effective diameter, the weighted average offset estimation and the merging weight obtain equal Root frequency deviation extends, and estimates as doppler spread.

2. method according to claim 1, it is characterised in that described that effective diameter is obtained according to channel impulse response, including：

Channel estimation in frequency domain is transformed into time domain, channel impulse response is obtained；

Obtain the power delay profile of each sampling point in the channel impulse response；

According to the power delay profile of each sampling point, power sequence is carried out；

The power of noise and interference is determined according to power sequence and maximum effective diameter bar number；

The peak power in the sequence of power and the power according to the noise and interference is determined for screening effective diameter Power threshold；

Sampling point using the power in described each sampling point more than the power threshold is used as effective diameter.

3. method according to claim 1, it is characterised in that the effective diameter correlation of each effective diameter of acquisition, and The offset estimation of each effective diameter described in phase acquisition according to the effective diameter correlation, including：

Obtain the effective diameter correlation of each effective diameter；

Effective diameter correlation to each effective diameter carries out phase extraction, and is carried according to the correlation of each effective diameter The phase for taking obtains the offset estimation of each effective diameter.

4. method according to claim 1, it is characterised in that it is described merged according to the power calculation of each effective diameter weigh Weight, merging is weighted by the offset estimation of each effective diameter with the merging weight, obtains weighted average offset estimation, Including：

Obtain the power summation of the available signal power of each effective diameter；

Using the ratio of the available signal power of each effective diameter and the power summation of the available signal power as it is described each The merging weight of effective diameter；

The offset estimation of each effective diameter is weighted merging with the merging weight, the weighted average frequency deviation is obtained Estimate.

5. method according to claim 2, it is characterised in that described when orthogonal frequency division multiplex OFDM system is applied to Channel estimation in frequency domain is transformed into time domain, channel impulse response is obtained, including：

When by the channel estimation in frequency domain carrying out Fast Fourier Transform Inverse IFFT, the channel estimation in frequency domain is transformed to Domain, obtains the channel impulse response；

The formula of the IFFT includes：

${\hat{h}}_{n,l}^{\left(TD\right)}={\mathrm{IFFT}}_{N_{FFT}}({\hat{h}}_{k,l}^{\left(FD\right)},k=0,1,...K-1),n=0,1,...N_{FFT}-1,l=0,1,...L-1$

Wherein,Represent and be located at l-th CRS OFDM symbol, k-th frequency domain of CRS RE in frequency direction on time orientation Channel estimation；Represent the value of n-th sampling point of the channel impulse response of l-th CRS OFDM symbols, N_FFTRepresent The points of the IFFT, the total sample of the channel impulse response is equal to N_FFT, K represents the sum of CRS RE in frequency direction, L represents the sum of CRS symbols on time orientation；

Wherein, when the IFFT is carried out, N is worked as_FFTDuring ＞ K, to the channel estimation in frequency domain in l-th CRS OFDM symbols Benefit 0 is carried out, the length of the channel estimation in frequency domain in l-th CRS OFDM symbols is equal to the N_FFT；Work as N_FFTDuring≤K, Take the N in the channel estimation in frequency domain in l-th CRS OFDM symbols_FFTIndividual sampling point carries out the IFFT.

6. method according to claim 2, it is characterised in that when ofdm system is applied to, the acquisition channel The power delay profile of each sampling point in impulse response, including：

Power averaging is carried out to the channel impulse response that each CRS OFDM symbol is calculated and obtains the power delay profile PDP；

Wherein, the formula for carrying out the power averaging includes：

${\widehat{\mathrm{\η}}}_n=\frac{1}{L}\underset{l=0}{\overset{L-1}{\Σ}}|{\hat{h}}_{n,l}^{\left(TD\right)}{|}^2,n=0,1,...N_{FFT}-1$

Wherein,N-th power of sampling point in the PDP is represented,Represent the channel of l-th CRS OFDM symbols The value of n-th sampling point of impulse response, N_FFTThe points of the IFFT are represented, the total sample of the channel impulse response is equal to N_FFT。

7. method according to claim 2, it is characterised in that when ofdm system is applied to, described in the basis each The power delay profile of sampling point, carries out power sequence, including：

By the power sequence in the power delay profileIt is ranked up according to power order from big to small, obtains the work( Rate sorts, and the power sequence includes new sequenceWherein

The power that noise and interference are determined according to power sequence and maximum effective diameter bar number, including：

Sorted according to the power, before prominent in described each sampling pointOther sampling points outside individual sampling point are true It is set to noise and interference sampling point；

According to noise and the acquisition noise and the power of interference of the rating formula of interference sampling point；

The computing formula of the power of the noise and interference sampling point includes：

${\mathrm{\σ}}^2=\frac{1}{N_{FFT}-N_{path}^{\max }}\underset{n=N_{path}^{\max }}{\overset{N_{FFT}-1}{\Σ}}{\widehat{\mathrm{\η}}}_{i_n}$

Wherein,Represent the maximum effective diameter bar number, N_FFTThe points of the IFFT are represented, the channel impulse response Total sample is equal to N_FFT, σ in prominent the one before sampling point²Represent the power of the noise and interference sampling point.

8. method according to claim 2, it is characterised in that described according to the noise when ofdm system is applied to Determine the power threshold for screening effective diameter with the peak power in power and the power sequence of interference, including：

The peak power in the sequence of power and the power according to the noise and interference, using power threshold computing formula Determine the power threshold；

The power threshold computing formula, including：

$\mathrm{\Γ}=max\{{\mathrm{\ρ}}_{noise}\·{\mathrm{\σ}}^2,{\mathrm{\ρ}}_{\max Path}\·{\widehat{\mathrm{\η}}}_{i_0}\}$

Wherein, Γ represents the power threshold, ρ_noiseRepresent noise gate coefficient, σ²Represent the work(of the noise and interference sampling point Rate, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in the power sequence.

9. method according to claim 3, it is characterised in that when ofdm system is applied to, each is effective for the acquisition The effective diameter correlation in footpath, including：

Using correlation value calculation formula, calculating the effective diameter of the same position in adjacent C RS OFDM symbols carries out effective diameter correlation Value；

The correlation value calculation formula includes：

${\hat{c}}_n^{\left(TD\right)}=\frac{1}{L-1}\underset{l=0}{\overset{L-2}{\Σ}}{\left({\hat{h}}_{i_n,l}^{\left(TD\right)}\right)}^{*}{\hat{h}}_{i_n,l+1}^{\left(TD\right)},n=0,1,...N_{path}-1$

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS OFDM symbol on time orientation Number channel impulse response sampling point i_nValue,Represent the l+1 channel punching of CRS OFDM symbols on time orientation Swash the sampling point i of response_nValue, wherein sampling point i_nIt is the sampling point as n-th effective diameter, N_pathRepresent the quantity of effective diameter.

10. method according to claim 3, it is characterised in that described to have to described each when ofdm system is applied to Imitating the effective diameter correlation in footpath carries out phase extraction, and obtains each according to the phase that the correlation of each effective diameter is extracted The offset estimation of effective diameter, including：

Phase extraction is carried out to the effective diameter correlation of each effective diameter using phase calculation formula；

The phase extracted using the correlation of frequency offset calculation formula each effective diameter according to obtains the frequency deviation of each effective diameter Estimate；

Wherein, the phase calculation formula includes：

${\widehat{\mathrm{\θ}}}_n=angle\left({\hat{c}}_n^{\left(TD\right)}\right),n=0,1,...N_{path}-1$

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent n-th effective diameter phase of effective diameter Pass is worth, N_pathRepresent the quantity of effective diameter；

The frequency offset calculation formula includes：

${\hat{O}}_n=\frac{{\widehat{\mathrm{\θ}}}_n}{2\mathrm{\π}T},n=0,1,...N_{path}-1$

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RSOFDM symbols.

11. methods according to claim 4, it is characterised in that when ofdm system is applied to, described in the acquisition each The power summation of the available signal power of effective diameter, including：

For described each effective diameter：The value that the power of effective diameter is subtracted the power of noise and interference is compared with zero, will Maximum in the two obtains the available signal power of each effective diameter as the available signal power of effective diameter；

Using power sum formula, the power summation of the available signal power of each effective diameter is obtained；

Wherein, the power sum formula includes：

${\hat{S}}_A^{\′}=\underset{n=0}{\overset{N_{path}-1}{\Σ}}{\widehat{\mathrm{\η}}}_{i_n}^{\′},{\widehat{\mathrm{\η}}}_{i_n}^{\′}=max({\widehat{\mathrm{\η}}}_{i_n}-{\mathrm{\σ}}^2,0)$

Wherein,The power summation is represented,N-th power of effective diameter is represented,Represent n-th effective diameter Available signal power, σ²Represent the power of the noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

12. methods according to claim 4, it is characterised in that when ofdm system is applied to, it is described to have described each Imitate the offset estimation in footpath and merging is weighted with the merging weight, obtain the weighted average offset estimation, including：

The offset estimation of each effective diameter is merged using weighted average frequency deviation formula, obtains the weighted average frequently Estimate partially；

Wherein, the weighted average frequency deviation formula, including：

$f_o=\underset{n=0}{\overset{N_{path}-1}{\Σ}}{w}_n\·{\hat{O}}_n,w_n=\frac{{\widehat{\mathrm{\η}}}_{i_n}^{\′}}{{\hat{S}}_A^{\′}}$

Wherein, f_oThe weighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has The merging weight of the offset estimation in footpath is imitated,The power summation is represented,Represent the useful signal of n-th effective diameter Power.

13. methods according to claim 1, it is characterised in that the offset estimation of each effective diameter described in the basis, institute Weighted average offset estimation and the merging weight are stated, the extension of root mean square frequency deviation is obtained, estimated as doppler spread, bag Include：

According to the offset estimation of each effective diameter, the merging of the weighted average offset estimation and each effective diameter Weight, obtains the root mean square frequency deviation and extends using root mean square extension computing formula；

Root mean square extension is estimated as the doppler spread；

Wherein, the root mean square extension computing formula includes：

$f_{Dopp}=\sqrt{\underset{n=0}{\overset{N_{path}-1}{\Σ}}{w}_n{({\hat{O}}_n-f_o)}^2}$

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresent n-th effective diameter Offset estimation merging weight, f_oRepresent the weighted average offset estimation, N_pathRepresent the quantity of effective diameter.

The determining device of frequency deviation and doppler spread under a kind of 14. high-speed mobile scenes, it is characterised in that described device bag Include：

Effective diameter acquisition module, for obtaining effective diameter according to channel impulse response；

Frequency deviation estimating modules, the effective diameter correlation for obtaining each effective diameter, and according to the phase of the effective diameter correlation Position obtains the offset estimation of each effective diameter；

Weighted average frequency deviation estimating modules, for merging weight according to the power calculation of each effective diameter, each is effective by described in The offset estimation in footpath is weighted merging with the merging weight, obtains weighted average offset estimation；

Doppler spread estimation module, for the offset estimation according to each effective diameter, the weighted average offset estimation And the merging weight, the extension of root mean square frequency deviation is obtained, estimate as doppler spread.

15. devices according to claim 14, it is characterised in that the effective diameter acquisition module, including：

Impulse response acquisition submodule, for channel estimation in frequency domain to be transformed into time domain, obtains channel impulse response；

Power delay profile acquisition submodule, the power-delay point for obtaining each sampling point in the channel impulse response Cloth；

Power sorting sub-module, for the power delay profile according to each sampling point, carries out power sequence；

Noise and the power determination sub-module of interference, for determining noise according to power sequence and maximum effective diameter bar number With the power of interference；

Power threshold determination sub-module, for the maximum work in power and the power sequence according to the noise and interference Rate determines the power threshold for screening effective diameter；

Effective diameter determination sub-module, for the sampling point using the power in described each sampling point more than the power threshold as effective Footpath.

16. devices according to claim 14, it is characterised in that the frequency deviation estimating modules, including：

Effective diameter correlation acquisition submodule, the effective diameter correlation for obtaining each effective diameter；

Offset estimation acquisition submodule, phase extraction is carried out for the effective diameter correlation to each effective diameter, and according to The phase that the correlation of each effective diameter is extracted obtains the offset estimation of each effective diameter.

17. devices according to claim 14, it is characterised in that the weighted average frequency deviation estimating modules, including：

Power summation acquisition submodule, the power summation of the available signal power for obtaining each effective diameter；

Merge Weight Acquisition submodule, for by the power of the available signal power of each effective diameter and the available signal power The ratio of summation as each effective diameter merging weight；

Weighted average offset estimation submodule, for the offset estimation of each effective diameter to be added with the merging weight Power merges, and obtains the weighted average offset estimation.

18. devices according to claim 15, it is characterised in that when ofdm system is applied to, the impulse response is obtained Submodule is taken, is used for：

When by the channel estimation in frequency domain carrying out Fast Fourier Transform Inverse IFFT, the channel estimation in frequency domain is transformed to Domain, obtains the channel impulse response；

The formula of the IFFT includes：

${\hat{h}}_{n,l}^{\left(TD\right)}={\mathrm{IFFT}}_{N_{FFT}}({\hat{h}}_{k,l}^{\left(FD\right)},k=0,1,...K-1),n=0,1,...N_{FFT}-1,l=0,1,...L-1$

Wherein,Represent and be located at l-th CRS OFDM symbol, k-th frequency domain of CRS RE in frequency direction on time orientation Channel estimation；Represent the value of n-th sampling point of the channel impulse response of l-th CRS OFDM symbols, N_FFTRepresent The points of the IFFT, the total sample of the channel impulse response is equal to N_FFT, K represents the sum of CRS RE in frequency direction, L represents the sum of CRS symbols on time orientation；

Wherein, when the IFFT is carried out, N is worked as_FFTDuring ＞ K, to the channel estimation in frequency domain in l-th CRS OFDM symbols Benefit 0 is carried out, the length of the channel estimation in frequency domain in l-th CRS OFDM symbols is equal to the N_FFT；Work as N_FFTDuring≤K, Take the N in the channel estimation in frequency domain in l-th CRS OFDM symbols_FFTIndividual sampling point carries out the IFFT.

19. devices according to claim 15, it is characterised in that when ofdm system is applied to, the power-delay point Cloth acquisition submodule, is used for：

Power averaging is carried out to the channel impulse response that each CRS OFDM symbol is calculated and obtains the power delay profile PDP；

Wherein, the formula for carrying out the power averaging includes：

${\widehat{\mathrm{\η}}}_n=\frac{1}{L}\underset{l=0}{\overset{L-1}{\Σ}}|{\hat{h}}_{n,l}^{\left(TD\right)}{|}^2,n=0,1,...N_{FFT}-1$

Wherein,N-th power of sampling point in the PDP is represented,Represent the channel of l-th CRS OFDM symbols The value of n-th sampling point of impulse response, N_FFTThe points of the IFFT are represented, the total sample of the channel impulse response is equal to N_FFT。

20. devices according to claim 15, it is characterised in that when ofdm system is applied to, power sequence Module, is used for：

By the power sequence in the power delay profileIt is ranked up according to power order from big to small, obtains the work( Rate sorts, and the power sequence includes new sequenceWherein

The noise and the power determination sub-module of interference, including：

Noise and interference sampling point determination sub-module, for being sorted according to the power, will be prominent in described each sampling point BeforeOther sampling points outside individual sampling point are defined as noise and interference sampling point；

Noise and the power acquisition submodule of interference, for described in the acquisition according to noise and the rating formula of interference sampling point Noise and the power of interference；

The computing formula of the power of the noise and interference sampling point includes：

${\mathrm{\σ}}^2=\frac{1}{N_{FFT}-N_{path}^{\max }}\underset{n=N_{path}^{\max }}{\overset{N_{FFT}-1}{\Σ}}{\widehat{\mathrm{\η}}}_{i_n}$

Wherein,Represent the maximum effective diameter bar number, N_FFTThe points of the IFFT are represented, the channel impulse response Total sample is equal to N_FFT, σ²Represent the power of the noise and interference sampling point.

21. devices according to claim 15, it is characterised in that when ofdm system is applied to, the power threshold is true Stator modules, are used for：

The peak power in the sequence of power and the power according to the noise and interference, using power threshold computing formula Determine the power threshold；

The power threshold computing formula, including：

$\mathrm{\Γ}=max\{{\mathrm{\ρ}}_{noise}\·{\mathrm{\σ}}^2,{\mathrm{\ρ}}_{\max Path}\·{\widehat{\mathrm{\η}}}_{i_0}\}$

Wherein, Γ represents the power threshold, ρ_noiseRepresent noise gate coefficient, σ²Represent the work(of the noise and interference sampling point Rate, ρ_maxPathMaximum diameter threshold coefficient is represented,Represent the peak power in the power sequence.

22. devices according to claim 16, it is characterised in that when ofdm system is applied to, the effective diameter is related Value acquisition submodule, is used for：

Using correlation value calculation formula, calculating the effective diameter of the same position in adjacent C RS OFDM symbols carries out effective diameter correlation Value；

The correlation value calculation formula includes：

${\hat{c}}_n^{\left(TD\right)}=\frac{1}{L-1}\underset{l=0}{\overset{L-2}{\Σ}}{\left({\hat{h}}_{i_n,l}^{\left(TD\right)}\right)}^{*}{\hat{h}}_{i_n,l+1}^{\left(TD\right)},n=0,1,...N_{path}-1$

Wherein,N-th effective diameter correlation of effective diameter is represented,Represent l-th CRS OFDM on time orientation The sampling point i of the channel impulse response of symbol_nValue,Represent the l+1 channel of CRS OFDM symbols on time orientation The sampling point i of impulse response_nValue, wherein sampling point i_nIt is the sampling point as n-th effective diameter, N_pathRepresent the number of effective diameter Amount.

23. devices according to claim 16, it is characterised in that when ofdm system is applied to, the offset estimation is obtained Submodule is taken, including：

Phase extraction submodule, for entering line phase to the effective diameter correlation of each effective diameter using phase calculation formula Extract；

Offset estimation determination sub-module, for the phase that the correlation using frequency offset calculation formula each effective diameter according to is extracted Position obtains the offset estimation of each effective diameter；

Wherein, the phase calculation formula includes：

${\widehat{\mathrm{\θ}}}_n=angle\left({\hat{c}}_n^{\left(TD\right)}\right),n=0,1,...N_{path}-1$

Wherein,N-th phase of the effective diameter correlation of effective diameter is represented,Represent n-th effective diameter phase of effective diameter Pass is worth, N_pathRepresent the quantity of effective diameter；

The frequency offset calculation formula includes：

${\hat{O}}_n=\frac{\widehat{\mathrm{\θ}}}{2\mathrm{\π}T},n=0,1,...N_{path}-1$

Wherein,N-th offset estimation of effective diameter is represented, T represents the time interval of adjacent C RS OFDM symbols.

24. devices according to claim 17, it is characterised in that when ofdm system is applied to, the power summation is obtained Submodule is taken, including：

Available signal power acquisition submodule, for for described each effective diameter：The power of effective diameter is subtracted into noise and is done The value of the power disturbed is compared with zero, using the maximum in the two as the available signal power of effective diameter, obtains described each The available signal power of individual effective diameter；

Power summation determination sub-module, for utilizing power sum formula, obtains the available signal power of each effective diameter Power summation；

Wherein, the power sum formula includes：

${\hat{S}}_A^{\′}=\underset{n=0}{\overset{N_{path}-1}{\Σ}}{\widehat{\mathrm{\η}}}_{i_n}^{\′},{\widehat{\mathrm{\η}}}_{i_n}^{\′}=max({\widehat{\mathrm{\η}}}_{i_n}-{\mathrm{\σ}}^2,0)$

Wherein,The power summation is represented,N-th power of effective diameter is represented,Represent n-th effective diameter Available signal power, σ²Represent the power of the noise and interference sampling point, N_pathRepresent the quantity of effective diameter.

25. devices according to claim 17, it is characterised in that when ofdm system is applied to, the weighted average is frequently Submodule is estimated partially, is used for：

The offset estimation of each effective diameter is merged using weighted average frequency deviation formula, obtains the weighted average frequently Estimate partially；

Wherein, the weighted average frequency deviation formula, including：

$f_o=\underset{n=0}{\overset{N_{path}-1}{\Σ}}{w}_n\·{\hat{O}}_n,w_n=\frac{{\widehat{\mathrm{\η}}}_{i_n}^{\′}}{{\hat{S}}_A^{\′}}$

Wherein, f_oThe weighted average offset estimation is represented,Represent n-th offset estimation of effective diameter, w_nRepresenting n-th has The merging weight of the offset estimation in footpath is imitated,The power summation is represented,Represent the useful signal of n-th effective diameter Power.

26. devices according to claim 14, it is characterised in that the doppler spread estimation module, including：

Root mean square frequency deviation extends acquisition submodule, and for the offset estimation according to each effective diameter, the weighted average is frequently The merging weight of estimation and each effective diameter, obtains the root mean square frequency deviation and expands using root mean square extension computing formula partially Exhibition；

Doppler spread estimates submodule, for root mean square extension to be estimated as the doppler spread；

Wherein, the root mean square extension computing formula includes：

$f_{Dopp}=\sqrt{\underset{n=0}{\overset{N_{path}-1}{\Σ}}{w}_n{({\hat{O}}_n-f_o)}^2}$

Wherein, f_DoppThe extension of root mean square frequency deviation is represented,Represent n-th offset estimation of effective diameter, w_nRepresent n-th effective diameter Offset estimation merging weight, f_oRepresent the weighted average offset estimation, N_pathRepresent the quantity of effective diameter.