CN104426817A  Channel estimation method and device  Google Patents
Channel estimation method and device Download PDFInfo
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 CN104426817A CN104426817A CN201310360610.8A CN201310360610A CN104426817A CN 104426817 A CN104426817 A CN 104426817A CN 201310360610 A CN201310360610 A CN 201310360610A CN 104426817 A CN104426817 A CN 104426817A
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Abstract
Description
Technical field
The present invention relates to the communications field, particularly a kind of channel estimation methods and device thereof.
Background technology
The channel circumstance change of radio communication is complicated, the quality of channel directly affects the communication quality of wireless communication system, therefore channel estimating is the prerequisite that wireless communication system provides higher data rate, only has and carries out channel estimating accurately to channel, and receiver could complete reception exactly.
At present, each communication system adopts the training sequence or data that insert known some in the Frame launched at transmitter for receiving terminal reception, described training sequence or data can regard reference signal as, thus the training sequence received according to receiving terminal or data carry out the channel estimation methods of channel estimating.LTE (LongTerm Evolution, Long Term Evolution) communication system is with MIMO(Multiple Input MultipleOutput, multipleinput, multipleoutput) and OFDM (Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexi) based on physical layer framework.In the channel estimating of LTE communication system, the given data for channel estimating that LTE system sends is the discrete reference signal (RS being distributed in time domain and frequency domain, Reference Signal), terminal first can estimate the channel estimating of these reference signal positions when receiving data, then can obtain the channel estimating of other positions according to interpolation, described interpolation is nonreference signal.As shown in Figure 1, Fig. 1 is the reference signal distribution map in two time slots on one, antenna port place subcarrier, and the R0 in figure all represents reference signal, and the signal on all the other positions is nonreference signal.The method calculating the channel estimating of described reference signal position is LS(Least Square, least square), the method calculating the channel estimating of nonreference signal position is MMSE(Minimum Mean Square Error, least meansquare error) filtering.This MMSE filtering method is based on the channel estimating of the reference signal position that LS obtains, and determines that the channel to nonreference signal position carries out the decision method of channel estimation value, obtains the channel estimation value of nonreference signal position according to this decision method.This decision method comprises: perform when determining that channel estimating is carried out in nonreference signal position the order of frequency domain filtering and timedomain filtering, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and exponent number.
Filtering can be divided into the filtering on frequency domain direction and the filtering on time domain direction.As shown in Figure 1, in figure, f indicated direction represents frequency domain direction, and t indicated direction represents time domain direction.The exponent number of filter is larger, and the performance of the signal that filtering obtains is higher, but computation complexity also can increase simultaneously.In addition, can carry out the estimation of frequencydomain and timedomain correlation when filtering, this correlation may be used for the approximate correlation judged between actual multiple subcarriers and between OFDM symbol.In practice, frequencyfiltering model and timedomain filtering model is used to carry out the estimation of correlation.Conventional frequencyfiltering model has even Time Delay Model, exponential decay model and linear attenuation model.Conventional timedomain filtering model has Jakes Power Spectrum Model and linear interpolation model.
In the prior art, simple in order to what design and calculate, the execution sequence of frequency domain filtering and timedomain filtering is certain, in addition, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and exponent number also all determine, but such design cannot be issued to the optimization of channel estimating performance in various scene.
Summary of the invention
The object of the present invention is to provide a kind of channel estimation methods and device thereof, can different decision methods be adopted according to different scenes to carry out channel estimating, improve the performance of channel estimating.
For solving the problems of the technologies described above, embodiments of the present invention provide a kind of channel estimation methods, comprising:
Utilize the first channel estimation value to measure decision parameter, described first channel estimation value carries out channel estimating according to reference signal and obtains, and described decision parameter is for characterizing the correlated characteristic of channel;
Decision method when channel estimating carried out to nonreference signal position is obtained according to described decision parameter;
According to described decision method, channel estimating is carried out to described nonreference signal, obtain second channel estimated value, using described second channel estimated value as final channel estimation value.
Embodiments of the present invention additionally provide a kind of channel estimating apparatus, comprising:
Measuring unit, for utilizing the first channel estimation value to measure decision parameter, described first channel estimation value carries out channel estimating according to the data of reference signal position and obtains, and described decision parameter is for characterizing the correlated characteristic of channel;
Acquiring unit, for obtaining decision method when carrying out channel estimating to nonreference signal position according to described decision parameter;
Processing unit, for carrying out channel estimating according to the data of described decision method to described nonreference signal position, obtains second channel estimated value, using described second channel estimated value as final channel estimation value;
Embodiment of the present invention in terms of existing technologies, when carrying out channel estimating to the data of nonreference signal position, first utilize the first channel estimation value to measure decision parameter, described first channel estimation value carries out channel estimating according to the data of reference signal position and obtains; Then decision method when channel estimating carried out to nonreference signal position is obtained according to described decision parameter; Then carry out channel estimating according to the data of described decision method to described nonreference signal position, obtain second channel estimated value, using described second channel estimated value as final channel estimation value.With prior art, in order to the execution sequence of the frequency domain filtering of simple use that designs and timedomain filtering is certain, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and the channel estimation methods determined of exponent number compare, diverse ways can be adopted to carry out channel estimating according to different scenes, improve the performance of channel estimating.
In addition, the described decision method obtained when carrying out channel estimating to nonreference signal position according to described decision parameter comprises: described moving velocity of terminal and the first threshold value preset are compared; When described moving velocity of terminal is greater than the first default thresholding, described when channel estimating carried out to nonreference signal position advanced row frequency domain filtering carry out timedomain filtering again; When described moving velocity of terminal is less than or equal to the first default thresholding, describedly first carries out timedomain filtering when channel estimating is carried out to nonreference signal position and carry out frequency domain filtering again.
By the sequencing of flexible configuration timedomain filtering, frequency domain filtering, can all obtain relative preferably performance under the scene that moving velocity of terminal is higher with lower, more excellent than the channel estimation methods performance of fixing filter sequence.
In addition, the described decision method obtained when carrying out channel estimating to nonreference signal position according to described decision parameter also comprises: the business of described maximum multipath time delay and multipath meansquare value compared with the second threshold value preset; When the business of described maximum multipath time delay and multipath meansquare value is greater than the second default threshold value, described is exponential decay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the second default threshold value, described is even delay model or linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position; Or
The business of described maximum multipath time delay and multipath meansquare value is compared with the 3rd threshold value preset; When the business of described maximum multipath time delay and multipath meansquare value is greater than the 3rd default threshold value, described is linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the 3rd default threshold value, described is even delay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position.
By selfadaptation flexible, frequency domain filter exponent number is set, can when guaranteed performance, at the situation decline low complex degree that selection of time is larger.
In addition, the described decision method obtained when carrying out channel estimating to nonreference signal position according to described decision parameter also comprises: the exponent number determining described frequency domain filtering according to described maximum multipath time delay, described maximum multipath time delay is larger, described frequency domain filter exponent number is less, described maximum multipath time delay is less, and described frequency domain filter exponent number is larger.
By selfadaptation flexible, frequency domain filter exponent number is set, can when guaranteed performance, at the situation decline low complex degree that He Ne laser is larger.
In addition, the described decision method obtained when carrying out channel estimating to nonreference signal position according to described decision parameter also comprises: described moving velocity of terminal and the 4th threshold value preset are compared; When described moving velocity of terminal is greater than the 4th default threshold value, described when channel estimating carried out to nonreference signal position timedomain filtering based on Doppler power spectra symbol between correlation models be Jakes Power Spectrum Model; When described moving velocity of terminal is greater than the 4th default threshold value, described when channel estimating carried out to nonreference signal position timedomain filtering based on Doppler power spectra symbol between correlation models be linear interpolation model.
A kind of immediate timedomain filtering model can be selected according to the scene of reality by self adaptation, thus performance preferably channel estimation methods is provided.
In addition, the described decision method obtained when carrying out channel estimating to nonreference signal position according to described decision parameter also comprises: the exponent number determining described timedomain filtering according to described moving velocity of terminal, described moving velocity of terminal is larger, described timedomain filtering exponent number is less, described moving velocity of terminal is less, and described timedomain filtering exponent number is larger.
A kind of immediate timedomain filtering model can be selected according to the scene of reality by self adaptation, thus performance preferably channel estimation methods is provided.
Accompanying drawing explanation
Fig. 1 is the reference signal distribution map in two time slots in prior art on one, antenna port place subcarrier;
Fig. 2 is the channel estimation methods schematic flow sheet of first embodiment of the invention;
Fig. 3 is the channel estimating apparatus structural representation of seventh embodiment of the invention;
Fig. 4 is the acquiring unit structural representation of seventh embodiment of the invention;
Fig. 5 is the acquiring unit structural representation of eighth embodiment of the invention;
Fig. 6 is the acquiring unit structural representation of ninth embodiment of the invention;
Fig. 7 is the acquiring unit structural representation of tenth embodiment of the invention;
Fig. 8 is the acquiring unit structural representation of eleventh embodiment of the invention.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the embodiments of the present invention are explained in detail.But, persons of ordinary skill in the art may appreciate that in each execution mode of the present invention, proposing many ins and outs to make reader understand the application better.But, even without these ins and outs with based on the many variations of following execution mode and amendment, each claim of the application technical scheme required for protection also can be realized.
First embodiment of the invention provides a kind of channel estimation methods, and as shown in Figure 2, this channel estimation methods comprises:
S101, carry out channel estimating according to the data of reference signal position, obtain the first channel estimation value.
First channel estimation value is vector or matrix.This step is same as the prior art, does not repeat them here.
S102, utilize first channel estimation value measure decision parameter.
Decision parameter, for characterizing the correlated characteristic of channel, specifically comprises one of following or its combination in any: maximum multipath time delay, multipath meansquare value and moving velocity of terminal.
The method utilizing the first channel estimation value to measure decision parameter is prior art, and therefore not to repeat here in the present invention.
S103, obtain decision method when channel estimating carried out to nonreference signal position according to described decision parameter.
Decision method when carrying out channel estimating to nonreference signal position comprises: when nonreference signal position channel estimating performs, the sequencing of frequency domain filtering and timedomain filtering, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and exponent number.
Comprise according to the decision method that described decision parameter obtains when carrying out channel estimating to nonreference signal position:
The moving velocity of terminal obtained will be measured in step s 102, compare with the first threshold value preset; When described moving velocity of terminal is greater than the first default thresholding, when carrying out channel estimating to nonreference signal position, advanced row frequency domain filtering carries out timedomain filtering again; When described moving velocity of terminal is less than or equal to the first default thresholding, first carries out timedomain filtering when channel estimating is carried out to nonreference signal position and carry out frequency domain filtering again.
The speed of fast mobile terminal all can have an impact to the frequency domain characteristic of signal and time domain specification, when moving velocity of terminal is very fast, the frequency domain of signal can produces Doppler frequency shift diffusion, thus cause the time selective fading of signal in time domain.Therefore, when moving velocity of terminal is larger, first performs frequency domain filtering and carry out timedomain filtering again.
In actual applications, the first thresholding preset can get 30km(km)/h(hour) value between ~ 100km/h, concrete value size can adjust according to the needs of practical application.
Example, suppose that the moving velocity of terminal that step S102 measurement obtains is 90km/h, the first thresholding preset is 60km/h, because moving velocity of terminal is that to be greater than the first default thresholding be 60km/h to 90km/h, then step S103 can adjudicate advanced row frequency domain filtering when obtaining carrying out channel estimating to nonreference signal position in this scene channel and carries out timedomain filtering again.
In the step S103 of the embodiment of the present invention, only obtain the sequencing of execution TimeFrequency Domain Filtering when channel estimating carried out to nonreference signal position and timedomain filtering according to decision parameter, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and exponent number still conventionally in method determine.
S104, carry out channel estimating according to the data of described decision method to described nonreference signal position, obtain second channel estimated value, using described second channel estimated value as final channel estimation value.
Specifically, in this step, according in step s 103 judge obtain channel estimating is carried out to nonreference signal position time, perform the sequencing of TimeFrequency Domain Filtering and timedomain filtering, and crosscorrelation model between the subcarrier of the frequency domain filtering based on distribution of multipath time delay determined in prior art and exponent number, based on Doppler power spectra symbol between correlation models and exponent number, channel estimating is carried out to the data of described nonreference signal position.
Embodiment of the present invention in terms of existing technologies, when carrying out channel estimating to the data of nonreference signal position, first utilize the first channel estimation value to measure decision parameter, the first channel estimation value carries out channel estimating according to the data of reference signal position and obtains; Then decision method when channel estimating carried out to nonreference signal position is obtained according to described decision parameter; Then carry out channel estimating according to the data of described decision method to described nonreference signal position, obtain second channel estimated value, using described second channel estimated value as final channel estimation value.With prior art, in order to the execution sequence of the frequency domain filtering of simple use that designs and timedomain filtering is certain, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and the channel estimation methods determined of exponent number compare, the judgement of the execution sequence of frequency domain filtering and timedomain filtering can be carried out according to the speed of fast mobile terminal in different scenes, carrying out filtering when channel estimating according to the corresponding filter sequence that moving velocity of terminal is corresponding can obtain than fixing filter sequence preferably performance, improve the performance of channel estimating.
Second embodiment of the invention provides a kind of channel estimation methods, second execution mode is substantially identical with the first execution mode, difference part is: in the first embodiment, according to the comparative result of moving velocity of terminal with the first threshold value preset, decisionmaking is in the channel estimating of nonreference signal position, be that advanced row frequency domain filtering carries out timedomain filtering again, still first carry out timedomain filtering and carry out frequency domain filtering again.And in the present embodiment, the sequencing of frequency domain filtering and timedomain filtering still can be determined by prior art, but need comparing according to the business of maximum multipath time delay and multipath meansquare value and the second default threshold value or the 3rd threshold value, the crosscorrelation model between the subcarrier of the frequency domain filtering based on distribution of multipath time delay in the channel estimating of decisionmaking nonreference signal position.
Specifically, in the process performing step S103, comprise according to the decision method that decision parameter obtains when carrying out channel estimating to nonreference signal position: the business of described maximum multipath time delay and multipath meansquare value is compared with the second threshold value preset; When the business of described maximum multipath time delay and multipath meansquare value is greater than the second default threshold value, described is exponential decay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the second default threshold value, described is even delay model or linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position.In the step S103 of the embodiment of the present invention, only according to described decision parameter obtain channel estimating carried out to nonreference signal position time based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model, perform the sequencing of TimeFrequency Domain Filtering and timedomain filtering, frequency domain filtering exponent number, based on Doppler power spectra symbol between correlation models and exponent number still conventionally in method determine.
Multipath delay is that signal is propagated the signal in different path when receiving caused in the channel and arrived the time difference of receiving terminal along different paths, maximum multipath time delay represents the time difference between the signal component arrived the earliest and the signal component arrived at the latest, and multipath meansquare value represents root mean square time delay.
At present, based on the frequency domain filtering of distribution of multipath time delay subcarrier between totally three kinds, crosscorrelation model: exponential decay model, evenly delay model and linear attenuation model.Abovementioned three kinds of models cut both ways, and exponential decay model calculates more complicated, but closer to the channel scenario of reality; Even delay model calculates simple, but substantially cannot close to actual channel scenario; The calculating complexity of linear attenuation model and performance are between abovementioned two kinds of models.
In actual applications, the second threshold value preset can get the value between 2 ~ 20, and concrete value size can adjust according to the needs of practical application.
Example, suppose that the business of the maximum multipath time delay that step S102 measurement obtains and multipath meansquare value is 6, the second threshold value 8 preset, because the business of maximum multipath time delay and multipath meansquare value is less than the second default threshold value, be even delay model or linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when therefore channel estimating being carried out to nonreference signal position.
Or, the crosscorrelation model between present embodiment can obtain in the following way based on the subcarrier of the frequency domain filtering of distribution of multipath time delay:
The business of described maximum multipath time delay and multipath meansquare value is compared with the 3rd threshold value preset; When the business of described maximum multipath time delay and multipath meansquare value is greater than the 3rd default threshold value, described is linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the 3rd default threshold value, described is even delay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when carrying out channel estimating to nonreference signal position.
In actual applications, the 3rd thresholding preset can get the value between 1 ~ 5, and concrete value size can adjust according to the needs of practical application.
Example, suppose that the business of the maximum multipath time delay that step S102 measurement obtains and multipath meansquare value is 6, the 3rd threshold value 4 preset, because the business of maximum multipath time delay and multipath meansquare value is greater than the 3rd default threshold value, be linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when therefore channel estimating being carried out to nonreference signal position.
Or, the crosscorrelation model between present embodiment can obtain in the following way based on the subcarrier of the frequency domain filtering of distribution of multipath time delay:
The business of described maximum multipath time delay and multipath meansquare value is compared with the second threshold value preset and the 3rd default threshold value simultaneously; When the business of described maximum multipath time delay and multipath meansquare value is less than the second default threshold value, be even delay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when channel estimating carried out to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is more than or equal to the second default threshold value and is less than described the 3rd default threshold value simultaneously, be linear attenuation model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when channel estimating carried out to nonreference signal position; When the business of described maximum multipath time delay and multipath meansquare value is more than or equal to the 3rd default threshold value, be exponential decay model based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay when channel estimating carried out to nonreference signal position.
It should be noted that, the prerequisite that the present embodiment is set up is that described the second default threshold value is less than described the 3rd default threshold value.
Example, suppose that the business of the described maximum multipath time delay that step S102 measurement obtains and multipath meansquare value is 3, described the second default threshold value 2, described the 3rd default threshold value 5, business due to described maximum multipath time delay and multipath meansquare value meets and is greater than described the second default threshold value and is less than described the 3rd default threshold value simultaneously, when therefore judging to obtain to carry out channel estimating to nonreference signal position based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay as linear attenuation model.
So, immediate frequencyfiltering model can be selected according to different scenes, improve the performance of channel estimating.
Third embodiment of the invention provides a kind of channel estimation methods, 3rd execution mode is substantially identical with the first execution mode, difference part is: in the first embodiment, according to the comparative result of moving velocity of terminal with the first threshold value preset, decisionmaking is in the channel estimating of nonreference signal position, be that advanced row frequency domain filtering carries out timedomain filtering again, still first carry out timedomain filtering and carry out frequency domain filtering again.And in the present embodiment, the sequencing of frequency domain filtering and timedomain filtering still can be determined by prior art, but need the exponent number carrying out the frequency domain filtering in the channel estimating of decisionmaking nonreference signal position according to maximum multipath time delay.
In the process performing step S103, also comprise according to the decision method that described decision parameter obtains when carrying out channel estimating to nonreference signal position: the exponent number determining described frequency domain filtering according to described maximum multipath time delay, described maximum multipath time delay is larger, described frequency domain filter exponent number is less, described maximum multipath time delay is less, and described frequency domain filter exponent number is larger.In the step S103 of the embodiment of the present invention, only obtain exponent number nonreference signal position being carried out to channel estimating TimeFrequency Domain Filtering according to described decision parameter, perform the sequencing of TimeFrequency Domain Filtering and timedomain filtering, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model, based on Doppler power spectra symbol between correlation models and exponent number still conventionally in method determine.
In actual applications, the span of maximum multipath time delay is 0us(microsecond) ~ 20us, the span of frequency domain filter exponent number is 2 ~ 24.Example, between maximum multipath time delay and frequency domain filter exponent number, the corresponding relation of value can reference table 1.
Table 1
Example, suppose that the value of the maximum multipath time delay that step S102 measurement obtains is 12us, table lookup and 1 can to obtain, when carrying out channel estimating to nonreference signal position in this channel scenario, advanced line frequency territory filter order is 5 ~ 9, and when namely carrying out channel estimating to nonreference signal position in this scene, advanced line frequency territory filter order is any one value in 5,6,7,8 and 9.
Corresponding relation between maximum multipath time delay and described frequency domain filter exponent number can be arranged according to the needs of practical application, and this is not restricted in the present invention.
So, under the prerequisite ensureing filtering performance, the selection of frequency domain filtering exponent number can be carried out according to different scenes, reduce the complexity of design of filter when frequency domain selectivity is comparatively large and time domain selectivity is large.
Four embodiment of the invention provides a kind of channel estimation methods, 4th execution mode is substantially identical with the first execution mode, difference part is: in the first embodiment, according to the comparative result of moving velocity of terminal with the first threshold value preset, decisionmaking is in the channel estimating of nonreference signal position, be that advanced row frequency domain filtering carries out timedomain filtering again, still first carry out timedomain filtering and carry out frequency domain filtering again.And in the present embodiment, the sequencing of frequency domain filtering and timedomain filtering still can be determined by prior art, but need according to by described moving velocity of terminal with preset the 4th threshold value compare, come decisionmaking timedomain filtering based on Doppler power spectra symbol between correlation models.
In the process performing step S103, comprise according to the decision method that described decision parameter obtains when carrying out channel estimating to nonreference signal position: described moving velocity of terminal and the 4th threshold value preset are compared; When described moving velocity of terminal is greater than the 4th default threshold value, described when channel estimating carried out to nonreference signal position timedomain filtering based on Doppler power spectra symbol between correlation models be Jakes Power Spectrum Model; When described moving velocity of terminal is less than the 4th default threshold value, when channel estimating carried out to nonreference signal position timedomain filtering based on Doppler power spectra symbol between correlation be linear interpolation model.In the step S103 of the embodiment of the present invention, only according to described decision parameter obtain channel estimating carried out to nonreference signal position time based on Doppler power spectra symbol between correlation models, perform the sequencing of TimeFrequency Domain Filtering and timedomain filtering, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, timedomain filtering exponent number still conventionally in method determine.
At present, timedomain filtering based on Doppler power spectra symbol between correlation totally two kinds: Jakes Power Spectrum Model and linear interpolation model.Jakes Power Spectrum Model accuracy is higher, but the complexity of design is relatively high, and linear interpolation model more described Jakes Power Spectrum Model accuracy is lower, but the complexity of design is also relatively low.
In actual applications, the 4th threshold value preset can get the value between 30km/h ~ 150km/h, and concrete value size can adjust according to the needs of practical application.
Example, suppose that the moving velocity of terminal that step S102 measurement obtains is 90km/h, the 4th threshold value preset is 100km/h, because moving velocity of terminal is that 90km/h is less than the 4th default threshold value 100km/h, then can to adjudicate when obtaining carrying out channel estimating to nonreference signal position described in this channel scenario based on the correlation models between the symbol of Doppler power spectra is linear interpolation model.
So, immediate timedomain filtering model can be selected according to different scenes, improve the performance of channel estimating.
Fifth embodiment of the invention provides a kind of channel estimation methods, 5th execution mode is substantially identical with the first execution mode, difference part is: in the first embodiment, according to the comparative result of moving velocity of terminal with the first threshold value preset, decisionmaking is in the channel estimating of nonreference signal position, be that advanced row frequency domain filtering carries out timedomain filtering again, still first carry out timedomain filtering and carry out frequency domain filtering again.And in the present embodiment, the sequencing of frequency domain filtering and timedomain filtering still can be determined by prior art, but need the exponent number determining described timedomain filtering according to described moving velocity of terminal.
In the process performing step S103, comprise according to the decision method that described decision parameter obtains when carrying out channel estimating to nonreference signal position: the exponent number determining described timedomain filtering according to described moving velocity of terminal, moving velocity of terminal is larger, timedomain filtering exponent number is less, moving velocity of terminal is less, and timedomain filtering exponent number is larger.In the step S103 of the embodiment of the present invention, only according to described decision parameter obtain channel estimating carried out to nonreference signal position time timedomain filtering exponent number, the correlation models between the crosscorrelation model between the sequencing of described execution TimeFrequency Domain Filtering and timedomain filtering, the subcarrier of the described frequency domain filtering based on distribution of multipath time delay and exponent number, the described symbol based on Doppler power spectra still conventionally in method determine.
In actual applications, the scope of moving velocity of terminal is 0km/h ~ 500km/h, and the scope of the exponent number of timedomain filtering is 2 ~ 6.Determining according to described moving velocity of terminal, in the method for described timedomain filtering, first can arrange multiple thresholding, then carrying out corresponding according to described multiple thresholding segmentation with the exponent number of described timedomain filtering.Example, for described moving velocity of terminal, the first default cervical orifice of uterus is limited to 50km/h, and the second default cervical orifice of uterus is limited to 100km/h.Then more described moving velocity of terminal and described the first default cervical orifice of uterus is limit and described the second default cervical orifice of uterus is limit size.When described moving velocity of terminal is less than described the first default cervical orifice of uterus in limited time, can arrange described timedomain filtering exponent number is 5 or 6; Be more than or equal to described the first default cervical orifice of uterus limit when described moving velocity of terminal and be less than described the second default cervical orifice of uterus in limited time simultaneously, can arrange described timedomain filtering exponent number is 3 or 4; When described moving velocity of terminal is more than or equal to described the second default cervical orifice of uterus in limited time, can arrange described timedomain filtering exponent number is 2.Corresponding relation between described moving velocity of terminal and described time domain filtering exponent number can be arranged according to the needs of practical application, and this is not restricted in the present invention.
So, under the prerequisite ensureing filtering performance, the selection of timedomain filtering exponent number can be carried out according to different scenes, reduce the complexity of design of filter when frequency domain selectivity is comparatively large and time domain selectivity is large.
Sixth embodiment of the invention provides a kind of channel estimation methods, 5th execution mode is substantially identical with the first execution mode, difference part is: in the process performing step S103, according to the embodiment of the present invention one, the embodiment of the present invention two, the embodiment of the present invention three, the embodiment of the present invention four and the execution mode described in the embodiment of the present invention five obtain the sequencing of execution TimeFrequency Domain Filtering when carrying out channel estimating to nonreference signal position and timedomain filtering, crosscorrelation model between the subcarrier of the described frequency domain filtering based on distribution of multipath time delay and exponent number, based on Doppler power spectra symbol between correlation models and exponent number in one or more, for not according to the decision method that the execution mode in the embodiment of the present invention one to embodiment five obtains, can conventionally in method determine.
So, under the prerequisite ensureing filtering performance, the flexibility of channel estimation methods can be increased, also improves the accuracy of channel estimation methods simultaneously.
Seventh embodiment of the invention provides a kind of channel estimating apparatus 3, and as shown in Figure 3, described channel estimating apparatus 3 comprises:
Measuring unit 30, for utilizing the first channel estimation value to measure decision parameter, described first channel estimation value carries out channel estimating according to the data of reference signal position and obtains, and decision parameter is for characterizing the correlated characteristic of channel.
Acquiring unit 31, for obtaining decision method when carrying out channel estimating to nonreference signal position according to described decision parameter.
Decision parameter specifically comprises one of following or its combination in any: maximum multipath time delay, multipath meansquare value and moving velocity of terminal.
Processing unit 32, for carrying out channel estimating according to the data of described decision method to described nonreference signal position, obtains second channel estimated value, using described second channel estimated value as final channel estimation value.
Further, as shown in Figure 4, described acquiring unit 31 comprises following subelement:
First compares subelement 3101, for described moving velocity of terminal and the first threshold value preset being compared.
First judges subelement 3102, for when described moving velocity of terminal is greater than the first default thresholding, judge described when channel estimating carried out to nonreference signal position advanced person's row frequency domain filtering carry out timedomain filtering again.
Second judges subelement 3103, for when described moving velocity of terminal is less than or equal to the first default thresholding, judges describedly first to carry out timedomain filtering when carrying out channel estimating to nonreference signal position and carry out frequency domain filtering again.
Embodiment of the present invention in terms of existing technologies, when carrying out channel estimating to the data of nonreference signal position, first measuring unit utilizes the first channel estimation value to measure decision parameter, and described first channel estimation value carries out channel estimating according to the data of reference signal position and obtains; Then acquiring unit obtains decision method when carrying out channel estimating to nonreference signal position according to described decision parameter; Then processing unit carries out channel estimating according to the data of described decision method to described nonreference signal position, obtains second channel estimated value, using described second channel estimated value as final channel estimation value.With prior art, in order to the execution sequence of the frequency domain filtering of simple use that designs and timedomain filtering is certain, based on the frequency domain filtering of distribution of multipath time delay subcarrier between crosscorrelation model and exponent number, based on Doppler power spectra symbol between correlation models and the channel estimating apparatus determined of exponent number compare, the judgement of the execution sequence of frequency domain filtering and timedomain filtering can be carried out according to the speed of fast mobile terminal in different scenes, carrying out filtering when channel estimating according to the corresponding filter sequence that moving velocity of terminal is corresponding can obtain than fixing filter sequence preferably performance, improve the performance of channel estimating.
Eighth embodiment of the invention provides another kind of channel estimating apparatus, 8th execution mode is roughly the same with the 7th execution mode, as shown in Figure 5, main distinction part is: described acquiring unit is for obtaining the crosscorrelation model between the described subcarrier based on the frequency domain filtering of distribution of multipath time delay.
Described acquiring unit 31 also comprises following subelement:
Second compares subelement 3104, for the business of described maximum multipath time delay and multipath meansquare value and the second threshold value preset being compared.
3rd judges subelement 3105, for when the business of described maximum multipath time delay and multipath meansquare value is greater than the second default threshold value, judge described when channel estimating carried out to nonreference signal position based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay as exponential decay model.
4th judges subelement 3106, for when the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the second default threshold value, judge described when channel estimating carried out to nonreference signal position based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay as even delay model or linear attenuation model.
Or
Described second compares subelement 3104, for the business of described maximum multipath time delay and multipath meansquare value and the 3rd threshold value preset being compared.
3rd judges subelement 3105, for when the business of described maximum multipath time delay and multipath meansquare value is greater than the 3rd default threshold value, judge described when channel estimating carried out to nonreference signal position based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay as linear attenuation model.
4th judges subelement 3106, for when the business of described maximum multipath time delay and multipath meansquare value is less than or equal to the 3rd default threshold value, judge described when channel estimating carried out to nonreference signal position based on the crosscorrelation model between the subcarrier of the frequency domain filtering of distribution of multipath time delay as even delay model.
So, described acquiring unit can select immediate frequencyfiltering model according to different scenes, improve the performance of channel estimating.
Ninth embodiment of the invention provides another kind of channel estimating apparatus, and the 9th execution mode is roughly the same with the 7th execution mode, and as shown in Figure 6, main distinction part is: described acquiring unit is for obtaining the exponent number of described frequency domain filtering.
Described acquiring unit 31 also comprises following subelement:
First determines subelement 3107, and for determining the exponent number of described frequency domain filtering according to described maximum multipath time delay, described maximum multipath time delay is larger, and described frequency domain filter exponent number is less, and described maximum multipath time delay is less, and described frequency domain filter exponent number is larger.
So, described acquiring unit under the prerequisite ensureing filtering performance, can carry out the selection of frequency domain filtering exponent number according to different scenes, reduce the complexity of design of filter when frequency domain selectivity is comparatively large and time domain selectivity is large.
Tenth embodiment of the invention provides another kind of channel estimating apparatus, tenth execution mode is roughly the same with the 7th execution mode, as shown in Figure 7, main distinction part is: described acquiring unit is for obtaining the correlation models between the described symbol based on Doppler power spectra.
Described acquiring unit 31 also comprises following subelement:
3rd compares subelement 3108, for described moving velocity of terminal and the 4th threshold value preset being compared;
5th judges subelement 3109, during for being greater than the 4th default threshold value when described moving velocity of terminal, judge described when channel estimating carried out to nonreference signal position timedomain filtering based on Doppler power spectra symbol between correlation models as Jakes Power Spectrum Model;
6th judges subelement 3110, during for being greater than the 4th default threshold value when described moving velocity of terminal, judge described when channel estimating carried out to nonreference signal position based on the correlation models between the symbol of Doppler power spectra as linear interpolation model.
So, described acquiring unit can select immediate timedomain filtering model according to different scenes, improve the performance of channel estimating.
Eleventh embodiment of the invention provides another kind of channel estimating apparatus, and the 11 execution mode is roughly the same with the 7th execution mode, and as shown in Figure 8, main distinction part is: described acquiring unit is for obtaining the exponent number of described timedomain filtering.
Described acquiring unit 31 also comprises following subelement:
Second determines subelement 3111, and for determining the exponent number of described timedomain filtering according to described moving velocity of terminal, described moving velocity of terminal is larger, and described timedomain filtering exponent number is less, and described moving velocity of terminal is less, and described timedomain filtering exponent number is larger.
So, described acquiring unit under the prerequisite ensureing filtering performance, can carry out the selection of timedomain filtering exponent number according to different scenes, reduce the complexity of design of filter when frequency domain selectivity is comparatively large and time domain selectivity is large.
It is worth mentioning that, each module involved in present embodiment is logic module, and in actual applications, a logical block can be a physical location, also can be a part for a physical location, can also realize with the combination of multiple physical location.The operation principle of each physical location can describing in reference method embodiment, and the present invention does not repeat them here.In addition, in order to outstanding innovative part of the present invention, the unit not too close with solving technical problem relation proposed by the invention is not introduced in present embodiment, but this does not show the unit that there is not other in present embodiment.
Persons of ordinary skill in the art may appreciate that the respective embodiments described above realize specific embodiments of the invention, and in actual applications, various change can be done to it in the form and details, and without departing from the spirit and scope of the present invention.
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