CN105743823A - Signal channel estimation method and device - Google Patents
Signal channel estimation method and device Download PDFInfo
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- CN105743823A CN105743823A CN201410756801.0A CN201410756801A CN105743823A CN 105743823 A CN105743823 A CN 105743823A CN 201410756801 A CN201410756801 A CN 201410756801A CN 105743823 A CN105743823 A CN 105743823A
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Abstract
The invention relates to the technical field of mobile communication and discloses a signal channel estimation method and device. The signal channel estimation method comprises following steps: caching the maximum multipath time delay spread of multiple subframes before a current subframe; obtaining a zero-forcing solution according to received cell pilot frequency position signals extracted from the time frequency two-dimensional signals received from the current subframe; estimating the maximum multipath time delay spread and Doppler expansion corresponding to the current subframe according to the zero-forcing solution; performing anti-jitter processing to a maximum multipath time delay spread estimation result based on the Doppler expansion and using the processed result as an updated maximum multipath time delay spread estimation value of the current subframe; determining correlation functions of signal channel impulse response according to the preset signal channel time delay power spectrum shape and the updated maximum multipath time delay spread; performing dynamic interception to obtain correlation function segment with corresponding according segment length according to the updated maximum multipath time delay spread, and performing frequency domain LMMSE filtering to the zero-forcing solution to obtain a signal channel estimation value. By means of the method, the accuracy of signal channel estimation is increased.
Description
Technical field
The present invention relates to mobile communication technology field, particularly to a kind of channel estimation methods and device.
Background technology
LTE (Long Term Evolution)/LTE-A (LTE-Advanced) system have employed OFDM (friendship frequency division multiplexing) multiple access technique, its physical resource includes OFDM symbol (in time domain) and several wireless resource blocks (on frequency domain) of time-frequency two-dimensional, and wherein each wireless resource block is made up of 12 subcarriers again.In existing terminal, the channel estimating of LTE (-A) system is generally based on what cell common pilots (CRS) realized, cell common pilots is embedded in several Radio Resource grids of each wireless resource block (RE (resource element)) by compartment of terrain, as shown in Figure 1.Wherein, Domain Index when k, l are respectively for resource element frequency domain index, resource element, R0、R1Respectively antenna port 0, reference marks in antenna port 1.
In prior art, LTE (-A) receives the channel estimating of terminal and comprises the steps:
Step 1, extracts the reception signal of cell common pilots CRS position from the time-frequency two-dimensional signal that present sub-frame receives, and is receiving the cell common pilots sequence that terminal local generation is identical with transmitting terminal simultaneously；Then the pilot frequency sequence signal of the pilot frequency locations received generated divided by this locality, it is thus achieved that compel null solution.
Step 2, by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, obtains the impulse response of time domain channel, and estimates this maximum multipath delay spread corresponding to urgent null solution.
Step 3, according to the channel delay Power Spectrum Model with robustness set in advance and the channel delay power spectrum determining reality according to the maximum multipath delay spread estimated in step 2, then determines that the correlation function of channel impulse response.
Step 4, intercepts fixing correlation function section, and the ZF channel estimating solution that step 1 is obtained carries out frequency domain LMMSE filtering, it is thus achieved that more accurate channel estimating solution.
But, there is the deficiency of two aspects in above-mentioned prior art:
First, in estimating maximum multipath delay spread, robustness is not enough.Complexity due to wireless environment, terminal suffers from the interference of noise and adjacent cell when doing channel estimating, and this interference is random and time-varying, and the footpath corresponding to maximum multipath delay spread is often more weak, therefore, when running into somewhat larger interference, this footpath is just flooded by background noise.The inaccuracy estimated due to maximum multipath delay spread result in the inaccurate of channel estimation results.
Secondly, intercept fixing correlation function section to be filtered urgent null solution lacking adaptivity.Owing to needing the correlation function section inversion operation being intercepted when filtering, and inversion operation to consume substantial amounts of hardware resource, and the computing of this part has tended to take up most operand and computational complexity in channel estimating.Intercepting fixing correlation function section, be non-remunerative for the channel that actual multi-path delay spread is less, the performance boost exchanged for because it consumes substantial amounts of computing is only small；And be inadequate for the bigger channel of actual multi-path delay spread.
Summary of the invention
It is an object of the invention to provide a kind of channel estimation methods and device, making the channel maximum multipath delay spread that estimation obtains more accurate, thus improve the accuracy of channel estimating, improving receiver performance；Meanwhile, channel estimation methods has adaptivity flexibly, it is possible to make channel estimating performance and hardware complexity be compromised.
For solving above-mentioned technical problem, embodiments of the present invention provide a kind of channel estimation methods, comprise the steps of
The maximum multipath delay spread of the some subframes before receiving terminal buffer memory present sub-frame；
Receiving terminal extracts the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal that present sub-frame receives, and is simultaneously generated the cell common pilots sequence identical with transmitting terminal, and utilizes the signal of described pilot frequency locations divided by described pilot frequency sequence, obtains and compels null solution；
Receiving terminal, by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimates the maximum multipath delay spread corresponding to present sub-frame；Wherein, channel estimation sequence is channel impulse response；
Receiving terminal estimates doppler spread according to urgent null solution, to determine a weight coefficient sequence according to doppler spread, and summation that the maximum multipath delay spread estimated value weighting of some subframes before the weight coefficient sequence determined and present sub-frame and buffer memory is multiplied, it is thus achieved that the result after weighted sum is gone forward side by side row cache as the maximum multipath delay spread estimated value of the present sub-frame of renewal；
Receiving terminal determines the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining described channel impulse response；
Receiving terminal intercepts the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating, and utilizes the correlation function section intercepted to invert, and described urgent null solution carries out frequency-domain linear least mean-square error LMMSE filtering, it is thus achieved that channel estimating solution；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of described maximum multipath delay spread and intercepting.
Embodiments of the present invention additionally provide a kind of channel estimating apparatus, it is applied to receiving terminal, comprises: cache module, extraction module, generation module, urgent null solution acquisition module, maximum multipath delay spread estimation module, doppler spread estimation module, weight coefficient sequence determine that module, more new module, correlation function determine module, correlation function section interception module, channel estimating solution acquisition module；
Described cache module, for the maximum multipath delay spread estimated value of present sub-frame of maximum multipath delay spread and the renewal of the some subframes before buffer memory present sub-frame；
Described extraction module, for extracting the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal of present sub-frame reception；
Described generation module, for generating the cell common pilots sequence identical with transmitting terminal；
Described urgent null solution acquisition module, is used for the signal utilizing described pilot frequency locations divided by described pilot frequency sequence, obtains and compel null solution；
Described maximum multipath delay spread estimation module, for by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimating the maximum multipath delay spread corresponding to present sub-frame；Wherein, channel estimation sequence is channel impulse response；
Described doppler spread estimation module, for estimating doppler spread according to urgent null solution；
Described weight coefficient sequence determines module, for determining a weight coefficient sequence according to doppler spread；
Described more new module, for summation that the maximum multipath delay spread estimated value weighting of the weight coefficient determined sequence with present sub-frame and some subframes before of buffer memory is multiplied, it is thus achieved that the result after weighted sum is as the maximum multipath delay spread estimated value of the present sub-frame updated；
Described correlation function determines module, for determining the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining described channel impulse response；
Described correlation function section interception module, for intercepting the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of described maximum multipath delay spread and intercepting；
Described channel estimating solution acquisition module, for utilizing the correlation function section of intercepting to invert, and carries out frequency-domain linear least mean-square error LMMSE filtering, it is thus achieved that channel estimating solution to described urgent null solution.
Embodiment of the present invention is in terms of existing technologies, it is based on doppler spread to estimate to carry out stabilization process to maximum multipath delay spread, specifically, it it is the maximum multipath delay spread estimated value of the present sub-frame situation that is no longer only dependent upon present sub-frame, but determined by present sub-frame and some subframe weightings before, decrease the impact due to burst noise, interference etc., the channel maximum multipath delay spread making estimation is more accurate, thus improve the accuracy of channel estimating, improve receiver performance；And, intercept correlation function section based on maximum multipath delay spread adaptively, make channel estimation methods have adaptivity flexibly, it is possible to make channel estimating performance and hardware complexity be compromised.
It addition, in the step of the maximum multipath delay spread of some subframes before described receiving terminal buffer memory present sub-frame, it is possible to the only comprehensive maximum multipath delay spread value of buffer memory one；Wherein, this comprehensive maximum multipath delay spread value is the result of the maximum multipath delay spread value estimated by some subframes before comprehensive present sub-frame.Adopt the program, receiving terminal inner buffer comprehensive after present sub-frame maximum multipath delay spread estimated value, the information of some subframes before having contained, so, not only can improve the estimation performance of channel, and more save memory space.
It addition, intercept the step of the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating at described receiving terminal before, it is possible to comprise the steps of the segment length's mapping table pre-saving maximum multipath delay spread with correlation function section；Intercepting according to the maximum multipath delay spread after updating at described receiving terminal in the step of correlation function section of corresponding segment length, receiving terminal intercepts the correlation function section of corresponding segment length according to described mapping table and the maximum multipath delay spread after renewal.That is, the segment length's mapping table that can pre-save maximum multipath delay spread and correlation function section in Project Realization realizes, and namely falls into which span according to maximum multipath delay spread interval, is mapped to the correlation function segment length of correspondence, method is simple, it is easy to accomplish.
Accompanying drawing explanation
Fig. 1 is CRS pilot frequency design of the prior art；
Fig. 2 is the channel estimation methods schematic flow sheet according to first embodiment of the invention；
Fig. 3 is the channel estimation methods schematic flow sheet according to second embodiment of the invention；
Fig. 4 is the channel estimating apparatus structural representation according to third embodiment of the invention.
Detailed description of the invention
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, it will be understood by those skilled in the art that in each embodiment of the present invention, propose many ins and outs in order to make reader be more fully understood that the application.But, even without these ins and outs with based on the many variations of following embodiment and amendment, it is also possible to realize the application each claim technical scheme required for protection.
First embodiment of the present invention relates to a kind of channel estimation methods, and idiographic flow is as in figure 2 it is shown, comprise the steps of
Step 201, the maximum multipath delay spread of the some subframes before receiving terminal buffer memory present sub-frame, and segment length's mapping table of maximum multipath delay spread and correlation function section is set.For sake of convenience, by " the some subframes before present sub-frame " referred to as " before some subframes ".In the present embodiment, some subframes before of receiving terminal buffer memory preset number；Wherein, this preset number is the integer more than 1；And in the mapping table, span interval and correlation function segment length's one_to_one corresponding of maximum multipath delay spread, namely which span interval is maximum multipath delay spread fall into and be just mapped to the correlation function segment length of correspondence.
Step 202, receiving terminal extracts the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal that present sub-frame receives, and utilizes the signal acquisition of this pilot frequency locations to compel null solution.Specifically, in this step, the signal of the pilot frequency locations in the community extracting reception be simultaneously generated the cell common pilots sequence identical with transmitting terminal, and utilize the signal of pilot frequency locations divided by this pilot frequency sequence, obtain and compel null solution.This step is prior art, does not repeat them here.
Step 203, receiving terminal, by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimates the maximum multipath delay spread corresponding to present sub-frame and doppler spread.Wherein, channel estimation sequence is channel impulse response.This step is prior art, does not repeat them here.
In this step, receiving terminal estimates doppler spread by pilot frequency sequence carries out the mode of conjugate multiplication acquisition phase contrast.Estimating Doppler expands to prior art, does not repeat them here.When practical application, receiving terminal can also pass through to compare the phase contrast of the channel impulse response of current time slots and default comparison time slot in present sub-frame and obtain doppler spread.
Step 204, receiving terminal obtains, based on doppler spread, the maximum multipath delay spread value of present sub-frame updated and goes forward side by side row cache.
Specifically, in this step, following sub-step is comprised:
Step 2041, receiving terminal determines a weight coefficient sequence according to doppler spread.Wherein, this weight coefficient sequence isK is weight coefficient, and T is the buffer storage length of the maximum multipath delay spread of some subframes before of institute's buffer memory, and each weight coefficient is corresponding to the maximum multipath delay spread of a subframe, k0The maximum multipath delay spread of corresponding present sub-frame, k1The maximum multipath delay spread of previous sub-frame of corresponding present sub-frame, by that analogy.And, this weighting sequence has the following characteristics that
First, this weight coefficient sequence is accumulative equal to 1, namely
Secondly, the k in this weight coefficient sequence0It is the monotonically increasing function of doppler spread, front T-1 coefficient kiIt it is the monotonic decreasing function of doppler spread.Namely for k0, by doppler spread Dopple(1)The k obtained0 (1)With by doppler spread Dopple(2)The k obtained0 (2)If, Dopple(1)>Dopple(2), then k0 (1)>k0 (2).For (kT-1,kT-2,...,k1) it is then contrary situation.
Step 2042, the maximum multipath delay spread estimated value weighting of some subframes before the weight coefficient sequence determined and present sub-frame and buffer memory is multiplied summation by receiving terminal, it is thus achieved that the result after weighted sum is gone forward side by side row cache as the maximum multipath delay spread estimated value of the present sub-frame of renewal.In this step, the mode of the maximum multipath delay spread estimated value of the present sub-frame of receiving terminal buffer update is: the maximum multipath delay spread of subframe before all preservations is moved rearwards by one, the maximum multipath delay spread of T subframe before is removed, the maximum multipath delay spread estimated value of the present sub-frame updated is moved into.
Generally speaking, in step 204, the lifting of channel estimating performance is shown two aspects: first, the maximum multipath delay spread estimated value of present sub-frame is no longer only dependent upon the situation of present sub-frame, but determined by present sub-frame and some subframe weightings before, therefore improve the order of accuarcy of estimation, decrease the impact due to burst noise, interference etc..Secondly, the weight coefficient adopted is relative and doppler spread is adaptive, doppler spread reflection is receiving terminal (i.e. mobile terminal, it is called for short " UE ") speed of movement velocity, mean that when doppler spread is bigger the movement velocity of UE is fast, the change of its multi-path environment also relatively acutely, therefore gives present sub-frame more weight in weight coefficient sequence；Otherwise, if doppler spread is less means that the movement velocity of UE is slow, the change of its multi-path environment is also relatively slower, the more weight of subframe before therefore giving in weight coefficient sequence.Adaptive weighting makes the estimation of maximum multipath have more robustness.
Step 205, receiving terminal determines the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining channel impulse response.Wherein, channel delay spectrum shape set in advance can be following any one: rectangle, index shape or triangle, correspond respectively to rectangle spectrum, exponential spectrum and three angular spectrums.Correlation function is prior art to utilize maximum multipath delay spread to determine, does not repeat them here.
Channel estimation methods in present embodiment has adaptivity flexibly, the channel less for actual multi-path delay spread, correlation bandwidth is bigger, shortens the size of correlation matrix, saves computing and hardware consumption；The size of correlation matrix is added, thus obtaining bigger performance gain the channel relatively big for actual multi-path delay spread, correlation bandwidth is less.Owing to this adaptive algorithm is that the maximum multipath delay spread with actual channel matches, it is possible to obtain the better compromise of channel estimating performance and hardware complexity.
Step 206, receiving terminal intercepts the correlation function section of corresponding segment length according to mapping table and the maximum multipath delay spread after renewal, utilize the correlation function section intercepted to invert, and urgent null solution is carried out frequency domain LMMSE (linear minimum mean-squared error) filtering, it is thus achieved that channel estimating solution；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of maximum multipath delay spread and intercepting.Specifically, maximum multipath delay spread is big, intercepts shorter correlation function section, otherwise maximum multipath delay spread is little, then intercept longer correlation function section.
In wireless communications, maximum multipath delay spread is with correlation bandwidth inversely, therefore the maximum multipath delay spread that basis estimates is adaptively adjusted the segment length of correlation function and can average out in channel estimating performance and hardware spending, when the correlation bandwidth of reality is less, it is possible to reduce unnecessary hardware spending.
Compared with prior art, it is based on doppler spread to estimate to carry out stabilization process to maximum multipath delay spread, decrease the impact due to burst noise, interference etc., the channel maximum multipath delay spread value making estimation is more accurate, thus improve the accuracy of channel estimating, improve receiver performance；And, intercept correlation function section based on maximum multipath delay spread adaptively, make channel estimation methods have adaptivity flexibly, it is possible to make channel estimating performance and hardware complexity be compromised.
Second embodiment of the present invention relates to a kind of channel estimation methods.Second embodiment and the first embodiment are roughly the same, and main distinction part is in that: in the first embodiment, and before receiving terminal buffer memory is multiple, the maximum multipath delay spread of some subframes, improves channel estimating performance.And in second embodiment of the invention, the receiving terminal only comprehensive maximum multipath delay spread value of buffer memory one, so, not only can improve the estimation performance of channel, and more save memory space.
Specifically, in the present embodiment, comprise step 301～306, wherein, step 302,303,305 to 306 respectively to the step 202 in the first embodiment, 203,205 similar to 206, do not repeat them here.Only difference is introduced below:
In step 301, receiving terminal is the comprehensive maximum multipath delay spread value of buffer memory one only.Wherein, this comprehensive maximum multipath delay spread value is the result of the maximum multipath delay spread value estimated by some subframes before comprehensive present sub-frame.Receiving terminal inner buffer comprehensive after present sub-frame maximum multipath delay spread estimated value, the information of some subframes before having contained, so, not only can improve the estimation performance of channel, and more save memory space.
Specifically, in this step, if buffer memory first, the then maximum multipath delay spread of several subframes of buffer memory, and utilize the maximum multipath delay spread of several subframes of weight coefficient sequence and buffer memory to be weighted summation, obtain described comprehensive maximum multipath delay spread value, then discharge the maximum multipath delay spread of several subframes of buffer memory；Wherein, weight coefficient sequence isOtherwise, the only maximum multipath delay spread of a subframe before buffer memory present sub-frame, wherein, weight coefficient sequence is (k1,k0), this sequence is determined by doppler spread.
In step 304, if not buffer memory first, weight coefficient sequence then only has two values, i.e. (k1,k0), wherein, k1Corresponding comprehensive maximum multipath delay spread.And the mode of the maximum multipath delay spread estimated value of the present sub-frame of receiving terminal buffer update is: the comprehensive maximum multipath delay spread of the subframe before originally preserved is deleted, and the maximum multipath delay spread of the present sub-frame after renewal is inserted (the comprehensive maximum multipath delay spread being called present sub-frame).
Due to UE inner buffer comprehensive after present sub-frame maximum multipath delay spread estimated value, the information of some subframes before having contained, therefore equally possible lifting channel estimating performance, but more save memory space.
The step of various methods divides above, is intended merely to description clear, it is achieved time can be merged into a step or some step is split, and is decomposed into multiple step, as long as comprising identical logical relation, all in the protection domain of this patent；To adding inessential amendment in algorithm or in flow process or introducing inessential design, but do not change the core design of its algorithm and flow process all in the protection domain of this patent.
Third embodiment of the invention relates to a kind of channel estimating apparatus, it is applied to receiving terminal, as shown in Figure 4, comprise: cache module, extraction module, generation module, urgent null solution acquisition module, maximum multipath delay spread estimation module, doppler spread estimation module, weight coefficient sequence determine that module, more new module, correlation function determine module, correlation function section interception module, channel estimating solution acquisition module.
Cache module, for the maximum multipath delay spread estimated value of present sub-frame of maximum multipath delay spread and the renewal of the some subframes before buffer memory present sub-frame.In the present embodiment, the maximum multipath delay spread estimated value of the present sub-frame updated, by the maximum multipath delay spread of subframe before all preservations is moved rearwards by one and the maximum multipath delay spread of T subframe is before removed, is moved into by cache module.
Extraction module, for extracting the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal of present sub-frame reception.
Generation module, for generating the cell common pilots sequence identical with transmitting terminal.
Compel null solution acquisition module, be used for the signal utilizing pilot frequency locations divided by pilot frequency sequence, obtain and compel null solution.
Maximum multipath delay spread estimation module, for by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimating the maximum multipath delay spread corresponding to present sub-frame.Wherein, channel estimation sequence is channel impulse response.
Doppler spread estimation module, for estimating doppler spread according to urgent null solution.In the present embodiment, doppler spread estimation module can obtain the mode of phase contrast and estimate doppler spread by pilot frequency sequence carries out conjugate multiplication, or obtains doppler spread by comparing the phase contrast of the channel impulse response of current time slots and default comparison time slot in present sub-frame.
Weight coefficient sequence determines module, for determining a weight coefficient sequence according to doppler spread.
More new module, for summation that the maximum multipath delay spread estimated value weighting of the weight coefficient determined sequence with present sub-frame and some subframes before of buffer memory is multiplied, it is thus achieved that the result after weighted sum is as the maximum multipath delay spread estimated value of the present sub-frame updated.
Correlation function determines module, for determining the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining channel impulse response.
Correlation function section interception module, for intercepting the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of maximum multipath delay spread and intercepting.And, pre-save segment length's mapping table of maximum multipath delay spread and correlation function section in correlation function section interception module, for the correlation function section intercepting corresponding segment length according to this mapping table with the maximum multipath delay spread after renewal.
Channel estimating solution acquisition module, for utilizing the correlation function section of intercepting to invert, and carries out frequency domain LMMSE filtering, it is thus achieved that channel estimating solution to urgent null solution.
It is seen that, present embodiment is the system embodiment corresponding with the first embodiment, and present embodiment can be worked in coordination enforcement with the first embodiment.The relevant technical details mentioned in first embodiment is still effective in the present embodiment, in order to reduce repetition, repeats no more here.Correspondingly, the relevant technical details mentioned in present embodiment is also applicable in the first embodiment.
It is noted that each module involved in present embodiment is logic module, in actual applications, a logical block can be a physical location, it is also possible to be a part for a physical location, it is also possible to realize with the combination of multiple physical locations.Additionally, for the innovative part highlighting the present invention, do not introduced by the unit less close with solving technical problem relation proposed by the invention in present embodiment, but this is not intended that in present embodiment to be absent from other unit.
Four embodiment of the invention relates to a kind of channel estimating apparatus.4th embodiment and the 3rd embodiment are roughly the same, and main distinction part is in that: in the third embodiment, and before cache module buffer memory is multiple, the maximum multipath delay spread of some subframes, improves channel estimating performance.And in four embodiment of the invention, cache module is the comprehensive maximum multipath delay spread value of buffer memory one only；Wherein, this comprehensive maximum multipath delay spread value is the result combining the maximum multipath delay spread value estimated by some subframes before present sub-frame.So, channel estimating performance can not only be improved, it is also possible to save memory space.
Owing to the second embodiment is mutually corresponding with present embodiment, therefore present embodiment can be worked in coordination enforcement with the second embodiment.The relevant technical details mentioned in second embodiment is still effective in the present embodiment, and the technique effect that can reach in this second embodiment is in the present embodiment too it is achieved that in order to reduce repetition, repeat no more here.Correspondingly, the relevant technical details mentioned in present embodiment is also applicable in the second embodiment.
It will be understood by those skilled in the art that the respective embodiments described above are to realize specific embodiments of the invention, and in actual applications, it is possible in the form and details it is done various change, without departing from the spirit and scope of the present invention.
Claims (13)
1. a channel estimation methods, it is characterised in that comprise the steps of
The maximum multipath delay spread of the some subframes before receiving terminal buffer memory present sub-frame；
Receiving terminal extracts the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal that present sub-frame receives, and is simultaneously generated the cell common pilots sequence identical with transmitting terminal, and utilizes the signal of described pilot frequency locations divided by described pilot frequency sequence, obtains and compels null solution；
Receiving terminal, by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimates the maximum multipath delay spread corresponding to present sub-frame；Wherein, channel estimation sequence is frequency domain channel impulse response；
Receiving terminal estimates doppler spread according to urgent null solution, to determine a weight coefficient sequence according to doppler spread, and summation that the maximum multipath delay spread estimated value weighting of some subframes before the weight coefficient sequence determined and present sub-frame and buffer memory is multiplied, it is thus achieved that the result after weighted sum is gone forward side by side row cache as the maximum multipath delay spread estimated value of the present sub-frame of renewal；
Receiving terminal determines the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining described channel impulse response；
Receiving terminal intercepts the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating, and utilizes the correlation function section intercepted to invert, and described urgent null solution carries out frequency-domain linear least mean-square error LMMSE filtering, it is thus achieved that channel estimating solution；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of described maximum multipath delay spread and intercepting.
2. channel estimation methods according to claim 1, it is characterised in that in the step of the maximum multipath delay spread of the some subframes before described receiving terminal buffer memory present sub-frame,
The only comprehensive maximum multipath delay spread value of buffer memory one；
Wherein, this comprehensive maximum multipath delay spread value is the result of the maximum multipath delay spread value estimated by some subframes before comprehensive present sub-frame.
3. channel estimation methods according to claim 2, it is characterised in that in the step of the comprehensive maximum multipath delay spread value of described only buffer memory one,
If buffer memory first, the then maximum multipath delay spread of several subframes of buffer memory, and utilize the maximum multipath delay spread of several subframes of weight coefficient sequence and buffer memory to be weighted summation, obtain described comprehensive maximum multipath delay spread value, then discharge the maximum multipath delay spread of several subframes of buffer memory；Wherein, described weight coefficient sequence isK is weight coefficient, and T is the buffer storage length of the maximum multipath delay spread of some subframes of institute's buffer memory, and each weight coefficient is corresponding to the maximum multipath delay spread of a subframe, k0The maximum multipath delay spread of corresponding present sub-frame；And the k in this weight coefficient sequence0It is the monotonically increasing function of doppler spread, front T-1 coefficient kiIt it is the monotonic decreasing function of doppler spread；
Otherwise, the only maximum multipath delay spread of a subframe before buffer memory present sub-frame, wherein, weight coefficient sequence is (k1,k0), this sequence is determined by doppler spread.
4. channel estimation methods according to claim 1 and 2, it is characterised in that described weight coefficient sequence is
Wherein, k is weight coefficient, and T is the buffer storage length of the maximum multipath delay spread of some subframes before of institute's buffer memory, and each weight coefficient is corresponding to the maximum multipath delay spread of a subframe, k0The maximum multipath delay spread of corresponding present sub-frame；
And the k in this weight coefficient sequence0It is the monotonically increasing function of doppler spread, front T-1 coefficient kiIt it is the monotonic decreasing function of doppler spread.
5. channel estimation methods according to claim 4, it is characterised in that the result after described acquisition weighted sum go forward side by side as the maximum multipath delay spread estimated value of present sub-frame updated row cache step in,
The maximum multipath delay spread estimated value of the present sub-frame updated, by the maximum multipath delay spread of subframe before all preservations is moved rearwards by one and the maximum multipath delay spread of T subframe is before removed, is moved into by receiving terminal.
6. channel estimation methods according to claim 1, it is characterised in that intercept the step of correlation function section of corresponding segment length according to the maximum multipath delay spread after updating at described receiving terminal before, comprise the steps of
Pre-save segment length's mapping table of maximum multipath delay spread and correlation function section；
Intercept in the step of correlation function section of corresponding segment length according to the maximum multipath delay spread after updating at described receiving terminal,
Receiving terminal intercepts the correlation function section of corresponding segment length according to described mapping table and the maximum multipath delay spread after renewal.
7. channel estimation methods according to claim 1, it is characterised in that estimate in the step of doppler spread according to urgent null solution at described receiving terminal,
The mode obtaining phase contrast by described pilot frequency locations channel impulse response carries out conjugate multiplication estimates doppler spread；Or,
Doppler spread is obtained by comparing the phase contrast of the channel impulse response of current time slots and default comparison time slot in present sub-frame.
8. channel estimation methods according to claim 1, it is characterised in that described channel delay spectrum shape set in advance be following any one: rectangle, index shape or triangle.
9. a channel estimating apparatus, it is applied to receiving terminal, it is characterized by comprising: cache module, extraction module, generation module, compel null solution acquisition module, maximum multipath delay spread estimation module, doppler spread estimation module, weight coefficient sequence determine that module, more new module, correlation function determine module, correlation function section interception module, channel estimating solution acquisition module；
Described cache module, for the maximum multipath delay spread estimated value of present sub-frame of maximum multipath delay spread and the renewal of the some subframes before buffer memory present sub-frame；
Described extraction module, for extracting the signal of the pilot frequency locations of the community of reception from the time-frequency two-dimensional signal of present sub-frame reception；
Described generation module, for generating the cell common pilots sequence identical with transmitting terminal；
Described urgent null solution acquisition module, is used for the signal utilizing described pilot frequency locations divided by described pilot frequency sequence, obtains and compel null solution；
Described maximum multipath delay spread estimation module, for by carrying out Fourier transform according to the channel estimation sequence compeling null solution acquisition, estimating the maximum multipath delay spread corresponding to present sub-frame；Wherein, channel estimation sequence is channel impulse response；
Described doppler spread estimation module, for estimating doppler spread according to urgent null solution；
Described weight coefficient sequence determines module, for determining a weight coefficient sequence according to doppler spread；
Described more new module, for summation that the maximum multipath delay spread estimated value weighting of the weight coefficient determined sequence with present sub-frame and some subframes before of buffer memory is multiplied, it is thus achieved that the result after weighted sum is as the maximum multipath delay spread estimated value of the present sub-frame updated；
Described correlation function determines module, for determining the channel delay power spectrum of reality according to the maximum multipath delay spread of channel delay spectrum shape set in advance Yu renewal, and maps the correlation function determining described channel impulse response；
Described correlation function section interception module, for intercepting the correlation function section of corresponding segment length according to the maximum multipath delay spread after updating；Wherein, segment length's one_to_one corresponding of the correlation function section of the size of described maximum multipath delay spread and intercepting；
Described channel estimating solution acquisition module, for utilizing the correlation function section of intercepting to invert, and carries out frequency-domain linear least mean-square error LMMSE filtering, it is thus achieved that channel estimating solution to described urgent null solution.
10. channel estimating apparatus according to claim 9, it is characterised in that described cache module is the comprehensive maximum multipath delay spread value of buffer memory one only；
Wherein, this comprehensive maximum multipath delay spread value is the result combining the maximum multipath delay spread value estimated by some subframes before present sub-frame.
11. channel estimating apparatus according to claim 10, it is characterized in that, the maximum multipath delay spread estimated value of the present sub-frame updated, by the maximum multipath delay spread of subframe before all preservations is moved rearwards by one and the maximum multipath delay spread of T subframe is before removed, is moved into by described cache module.
12. channel estimating apparatus according to claim 9, it is characterized in that, segment length's mapping table of maximum multipath delay spread and correlation function section is pre-saved, for the correlation function section intercepting corresponding segment length according to this mapping table with the maximum multipath delay spread after renewal in described correlation function section interception module.
13. channel estimating apparatus according to claim 9, it is characterized in that, described doppler spread estimation module, mode for obtaining phase contrast by described pilot frequency locations channel impulse response carries out conjugate multiplication estimates doppler spread, or, obtain doppler spread by comparing the phase contrast of the channel impulse response of current time slots and default comparison time slot in present sub-frame.
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