CN101888354B - Method and device for estimating channel - Google Patents

Method and device for estimating channel Download PDF

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CN101888354B
CN101888354B CN 200910107414 CN200910107414A CN101888354B CN 101888354 B CN101888354 B CN 101888354B CN 200910107414 CN200910107414 CN 200910107414 CN 200910107414 A CN200910107414 A CN 200910107414A CN 101888354 B CN101888354 B CN 101888354B
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extracting multiple
frequency domain
link
quality
channel estimation
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CN101888354A (en
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李萍
孙维菊
秦洪峰
李斌
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ZTE Corp
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ZTE Corp
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Abstract

The invention discloses a method and a device for estimating a channel. The method comprises the following steps of: presetting extracting multiple of at least two stages, and dynamically determining the current extracting multiple according to link quality; according to the current extracting multiple, extracting a received frequency domain demodulation reference mark and a local frequency domain demodulation reference mark; and figuring out the current frequency domain chain estimated value by using the extracted received frequency domain demodulation reference mark and the local frequency domain demodulation reference mark. The device comprises an extracting multiple judging module, a pilot frequency extraction module and a channel estimation module, wherein the extracting multiple judging module is used for presetting the extracting multiple of the at least two stages, and dynamically determining the current extracting multiple according to the link quality; the pilot frequency extraction module is used for extracting the received frequency domain demodulation reference mark and the local frequency domain demodulation reference mark according to the current extracting multiple; and the channel estimation module is used for figuring out the current frequency domain chain estimated value through the extracted received frequency domain demodulation reference mark and the local frequency domain demodulation reference mark. The method and the device have the advantages of reducing the complexity of a receiver and reducing the processing time delay.

Description

A kind of channel estimation methods and device
Technical field
The present invention relates to moving communicating field, specifically, relate to a kind of channel estimation methods and device.
Background technology
Along with the fast development of global economy, the personal communication devices has presented microminiaturized and diversified, rolls up in conjunction with the demand of the aspects such as data service such as Multimedia Message, game on line, video request program, music download and mobile TV.3-G (Generation Three mobile communication system) (be called for short 3G) although the network wireless performance greatly improve, the reply market challenges with the field such as meet consumers' demand, a lot of limitations are still arranged.
LTE (Long Term Evolution) project is the new technology development project of the maximum of 3GPP (3G technology standard mechanism) startup over the past two years, and it improves and strengthened the aerial access technology of 3G.Compare with 3G, LTE has more technical advantage, is embodied in higher user data rate, grouping transmission, the improvement that reduces system delay, power system capacity and covering and the aspects such as reduction of operation cost.
LTE ul transmissions scheme adopts with the multiplexing multi-address system of the single carrier frequency division of Cyclic Prefix (SC-FDMA), can be mutually orthogonal at frequency domain between up user, and obtain effective frequency domain equalization in receiver one side, can reduce the peak-to-average power ratio of launch terminal, reduce volume and the cost of terminal.
In wireless communication system, the propagation path between transmitter and receiver is very complicated and changeable, and wireless channel can cause receiving the distortion of signal, comprises amplitude, phase place and frequency.In order correctly to solve originating terminal signal, channel estimating is the requisite part of receiver.In the SC-FDMA transmission plan of up employing with Cyclic Prefix, use DFT to obtain frequency-region signal, then insert nil symbol and carry out frequency spectrum shift, signal after moving again by IFFT (therefore, the SC-FDMA system also claims the DFT-S-OFDM system), and designed demodulated reference signal (3GPP TS 36.211: " Evolved Universal Terrestrial Radio Access (E-UTRA) in transmitted signal; Physicalchannels and modulation " in provided design rule and the using method of reference signal) be used for doing channel estimating; patent " uplink multi-user code field pilot channel estimating system and method for estimation "; publication number: CN200610140251.5 has provided the existing channel method of estimation.Yet, how reducing on Receiver Complexity and processing delay, prior art still has the improvements of needs.
Summary of the invention
Because above-mentioned background the invention provides a kind of channel estimation methods and device, can effectively reduce Receiver Complexity and processing delay.
In order to solve the problems of the technologies described above, the present invention has adopted following technical scheme:
A kind of channel estimation methods comprises the steps:
A, the default two-stage extracting multiple at least of extracting multiple judge module are dynamically determined current extracting multiple according to link-quality;
B, pilot tone abstraction module extract receiving frequency domain demodulation reference mark and local frequency domain demodulation reference mark according to described current extracting multiple;
C, channel estimation module are by calculating current channel estimation in frequency domain value through reception frequency domain demodulation reference mark and the local frequency domain demodulation reference mark that extracts.
Above-mentioned channel estimation methods, extracting multiple judge module dynamically determine that according to link-quality extracting multiple carries out as follows:
A1, judge that whether the frequency domain resource of CU is less than default number of resource blocks; In this way, determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, carry out next step;
A2, judge whether current link-quality is up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, heighten step by step current extracting multiple.
Above-mentioned channel estimation methods, described steps A 2, further carry out as follows:
Judge that whether link-quality continues in time period recently up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, carry out next step;
Judge that historical extracting multiple is whether identical in time period recently, in this way, determine that current extracting multiple is the high one-level extracting multiple of historical extracting multiple, otherwise, determine that current extracting multiple is extracting multiple last time.
Above-mentioned channel estimation methods, in described step C, channel estimation module calculates current channel estimation in frequency domain value by the reception frequency domain demodulation reference mark of passing through extraction and local frequency domain demodulation reference mark to carry out as follows:
C1, by the channel estimation in frequency domain value that calculates the pilot tone point that is drawn into through the reception frequency domain demodulation reference mark that extracts and local frequency domain demodulation reference mark;
The channel estimation in frequency domain value of C2, the pilot tone point that obtained not being drawn into by the channel estimation in frequency domain value of the pilot tone point that is drawn into;
C3, obtained the channel estimation value of non-pilot tone point by the channel estimation in frequency domain value of pilot tone point.
Above-mentioned channel estimation methods, the frequency domain estimated value of the described pilot tone point that is drawn into comprises following processing: its interference and noise that carries out in time domain is eliminated.
Above-mentioned channel estimation methods in described step C3, is obtained the channel estimation value employing filtering mode of non-pilot tone point by the channel estimation in frequency domain value of pilot tone point.
Above-mentioned channel estimation methods, in described steps A 2, judging that current link-quality is whether up to standard carries out as follows:
Default link-quality value up to standard determines that the link-quality measurement index whether greater than default link-quality value up to standard, in this way, determines that link-quality is up to standard; Otherwise link-quality is not up to standard; Wherein, described link-quality measurement index comprises signal to noise ratio, Block Error Rate or the signal to noise ratio of receive data and the combination of Block Error Rate.
The invention also discloses a kind of channel estimating apparatus, comprising:
Extracting multiple judge module: be used for default two-stage extracting multiple at least, dynamically determine current extracting multiple according to link-quality;
Pilot tone abstraction module: be used for according to described current extracting multiple, extract receiving frequency domain demodulation reference mark and local frequency domain demodulation reference mark;
Channel estimation module: be used for by calculating current channel estimation in frequency domain value through reception frequency domain demodulation reference mark and the local frequency domain demodulation reference mark that extracts.
Above-mentioned channel estimating apparatus, described extracting multiple judge module comprise frequency domain resource judging unit and link-quality judging unit up to standard, wherein:
Frequency domain resource judging unit: be used for judging that whether the frequency domain resource of CU is less than default number of resource blocks; In this way, determine that current extracting multiple is the lowermost level extracting multiple; Transfer to link-quality judging unit up to standard and continue judgement;
Link-quality judging unit up to standard: be used for judging whether current link-quality is up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, heighten step by step current extracting multiple.
Above-mentioned channel estimating apparatus, link-quality judging unit up to standard comprise that link-quality continues judging unit up to standard and historical extracting multiple judging unit, wherein:
Link-quality continues judging unit up to standard: be used for judge that link-quality is whether lasting up to standard in time period recently, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, transfer to historical extracting multiple judging unit and continue judgement;
Historical extracting multiple judging unit: be used for judging that historical extracting multiple is whether identical in time period recently, in this way, determine that current extracting multiple is the high one-level extracting multiple of historical extracting multiple, otherwise, determine that current extracting multiple is extracting multiple last time.
Compared with prior art, beneficial effect of the present invention is:
By the extracting multiple of default different stage, come the high-level or low-level extracting multiple of choice for use according to link-quality, and complete extraction to demodulation reference mark according to the extracting multiple of choosing, and finally realize channel estimating.Be appreciated that for channel estimating, sample point is more, channel estimating is more accurate, and obviously, more sample point will bring larger operand, thereby causes the complexity of receiver and the increase of processing delay.And the present invention can adjust extracting multiple according to link-quality,, use the extracting multiple of higher level, thereby reduced sample point preferably the time at link-quality, Receiver Complexity and processing delay are reduced, and do not lose the accuracy of channel estimating.
Description of drawings
Fig. 1 is the channel estimating apparatus module diagram that the self adaptation of example of the present invention reduces complexity;
Fig. 2 is the channel estimation methods flow chart that the self adaptation of example of the present invention reduces complexity;
Fig. 3 is the flow chart that the employing extraction mode of example of the present invention obtains the pilot bit channel estimating;
Fig. 4 is the pilot frequency locations schematic diagram of the SC-FDMA PUSCH of the system channel demodulation reference signal of example of the present invention.
Embodiment
The below's contrast accompanying drawing also elaborates to the present invention in conjunction with embodiment, should be appreciated that preferred embodiment described herein only is used for description and interpretation the present invention, is not intended to limit the present invention.
See also Fig. 1, the description that it is exemplary the system configuration of channel estimating apparatus of the present invention.In this embodiment, this channel estimating apparatus is arranged on receiver end, comprises extracting multiple module 101, pilot tone abstraction module 102, channel estimation module 103, link-quality judgement and update module 104.Wherein:
Extracting multiple judge module 101: be used for default two-stage extracting multiple at least, dynamically determine current extracting multiple according to link-quality;
Pilot tone abstraction module 102: be used for according to described current extracting multiple, extract receiving frequency domain demodulation reference mark and local frequency domain demodulation reference mark;
Channel estimation module 103: be used for by calculating current channel estimation in frequency domain value through reception frequency domain demodulation reference mark and the local frequency domain demodulation reference mark that extracts.Can see from diagram, in this example, channel estimation module 103 comprises pilot bit channel estimation module 1031 and non-pilot symbol channel estimation module 1032.These two modules will describe in detail later.
Link-quality judgement and update module 104 are used for safeguarding, upgrade link-quality state (current) according to current link-quality measurement index, for using next time.
Extracting multiple judge module 101 is mainly used in determining according to link-quality user's current extracting multiple, i.e. this extracting multiple that should use of user.In this article, " dynamically " word is used for showing that channel estimating may occur repeatedly, corresponding, extracting multiple is also repeatedly determined.Therefore, we represent " this " with " current " word, " last time " expression " this " once front, the front several times of " history " expression " this ".
In one embodiment, extracting multiple judge module 101 can comprise:
Frequency domain resource judging unit: be used for judging that whether the frequency domain resource of CU is less than default number of resource blocks; In this way, determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, transfer to link-quality judging unit up to standard and continue judgement;
Link-quality judging unit up to standard: be used for judging whether current link-quality is up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, heighten step by step current extracting multiple.
In another embodiment, link-quality judging unit up to standard can comprise:
Link-quality continues judging unit up to standard: be used for judge that link-quality is whether lasting up to standard in time period recently, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, transfer to historical extracting multiple judging unit and continue judgement;
Historical extracting multiple judging unit: be used for judging that historical extracting multiple is whether identical in time period recently, in this way, determine that current extracting multiple is the high one-level extracting multiple of historical extracting multiple, otherwise, determine that current extracting multiple is extracting multiple last time.
Above-mentioned frequency domain resource judging unit, link-quality judging unit up to standard, link-quality continue judging unit up to standard, historical extracting multiple judging unit, all do not indicate in the drawings.Obviously, those skilled in the art can on the basis of understanding its function, adopt the variety of ways such as software, hardware to go to realize these unit.
At first we illustrate the working method of extracting multiple judge module 101, and take the above-mentioned embodiment that comprises the lasting judging unit up to standard of link-quality and historical extracting multiple judging unit as example, the below supposes a user, and default at least two other extracting multiple of level.In addition, two registers have also been defined, i.e. link-quality status register R and extracting multiple level status register T.
Link-quality status register R, its long L that is set as, i.e. R=[r 1r 2R L], each bit of R represents the link-quality state that once receives, and below standard with 0 expression, 1 expression is up to standard.Judge the link-quality state whether the mode of employing up to standard be: default link-quality value up to standard, determine that the link-quality measurement index whether greater than default link-quality value up to standard, in this way, determines that link-quality is up to standard; Otherwise link-quality is not up to standard; Wherein, the link-quality measurement index comprises signal to noise ratio, Block Error Rate or the signal to noise ratio of receive data and the combination of Block Error Rate, certainly, also can take other link-quality measurement index.R is initialized as full 0, can adopt a left side to go out the right side to it and enter (in this example, with r 1Record link-quality state constantly far away, r 1The near link-quality state constantly of record) time flag r is farthest removed in sliding type updating maintenance 1The link-quality state of original record, and replace flag r 2The link-quality state of original record, the like, until by flag r L-1Record identification position r LIn the link-quality state of original record, and at flag r LIn record this link-quality state.As seen, recorded the history value of link-quality in the link-quality status register, extracting multiple judge module 101 can carry out determining of extracting multiple according to these link-quality history value.Link-quality state in the link-quality status register can be undertaken constantly sliding upgrading by aforesaid link-quality judgement and update module 104.
Extracting multiple level status register T, its long L, T=[t of being set as equally 1t 2T L], each bit of T represents the extracting multiple of the demodulated reference signal of a channel estimating, T is initialized as full NULL (invalid), can adopt a left side to go out the sliding type updating maintenance that the right side enters (principle and link-quality status register R are similar, repeat no more) to it.
Be appreciated that r 1Link-quality when the front L secondary channel that can represent this channel estimating (current) is estimated, in this article, with r 1Secondary channel is carved into r when estimating LThis section duration in the moment that secondary channel is estimated is defined as the nearest time period., when the mode bit of link-quality status register R is 1 entirely, can be judged to be in the duration at this section, within the time period recently, link-quality continues up to standard.
Extracting multiple level status register T reflects the selected extracting multiple of front L secondary channel estimation, on the whole, claim that these extracting multiple are historical extracting multiple, especially, the last secondary channel of this channel estimating is estimated that selected extracting multiple is called last time extracting multiple, obviously, last time extracting multiple is data in historical extracting multiple.
The process that extracting multiple is determined is:
(1) judge the frequency domain resource N that user m takies RB, mWhether less than default number of resource blocks, if so, make S i=S (1); If not, carry out (2);
Wherein, S is demodulated reference signal extracting multiple grade, and in this example, the extracting multiple grade is divided into C maxLevel, S (1)＜S (2)＜...＜S (C max), i is the numbering of user m up channel time sequencing, i.e. S iIndicate user m in i extracting multiple constantly, as mentioned above, can claim S iBe current extracting multiple, S i-1Be extracting multiple last time; S (1) is the lowermost level extracting multiple.Wherein, the subscript of S represents constantly, the number expression extraction grade in the S unquote.
(2) judge whether the mode bit in link-quality status register R has 0, if make S i=S (1); (being that link-quality is lasting up to standard within the time period recently), carry out (3) if not;
(3) judgement extracting multiple level status register T, if the sampling grade in register T has not identical (historical extracting multiple is not identical), make S i=S i-1If the grade in register T is identical (historical extracting multiple is identical) entirely, makes S iBe S i-1Grade put forward higher leveled extracting multiple, and upgrade extracting multiple level status register;
According to above-mentioned setting, be appreciated that when link-quality was up to standard, choosing step by step of current extracting multiple heightened.We suppose that a kind of link-quality continues situation up to standard, under initial condition, sampling grade in extracting multiple level status register T is not identical, but during along with each channel estimating, all choose last time extracting multiple as current extracting multiple and constantly update extracting multiple level status register T, can reach the complete identical situation of sampling grade in extracting multiple level status register T, at this moment, extracting multiple will improve a grade, then, after new grade continued for some time, extracting multiple will continue to improve until reach highest extracting multiple.Obvious, this routine extracting multiple is determined scheme, when link-quality is lasting up to standard, will present the stable trend that improves.This will improve the stability that extracting multiple is adjusted.
In addition, in the situation that link-quality is up to standard at the very start, choosing of extracting multiple can be arbitrarily, for example, can be arranged on equally lowermost level, to guarantee stability.
Pilot tone abstraction module 102 is used for pilot tone is extracted, and concrete, its process comprises:
At first, extract the frequency domain data D of the corresponding sub-carrier positions of targeted customer m in the frequency domain data that receives m
Then, extract M continuous pilot sub-carrier of frequency domain corresponding to targeted customer m that receives, obtain the frequency domain demodulation reference mark Y that length is M m(k), k=1 ..., M namely receives frequency domain demodulation reference mark;
To Y m(k) carry out S iDoubly extract, obtaining length is M/S iThe reception frequency domain demodulation reference mark
Figure G2009101074143D00081
K=1 ..., M/S i
Then, generate pilot tone demodulation reference mark X in this locality according to the mode of transmitting terminal m(k), i.e. local frequency domain demodulation reference mark, and it is carried out S iDoubly extract, obtaining length is M/S iLocal frequency domain demodulation reference mark
Figure G2009101074143D00082
K=1 ..., M/S i
Channel estimation module 103 is used for carrying out channel estimating, and is concrete, and it comprises pilot bit channel estimation module 1031 and non-pilot symbol channel estimation module 1032.
Pilot bit channel estimation module 1031 is used for pilot bit is carried out channel estimating, comprising: the channel estimation in frequency domain value of calculating the demodulation reference mark that extracts
Figure G2009101074143D00083
K=1 ..., M/S i
Will
Figure G2009101074143D00084
Do inversefouriertransform (IFFT) to time domain
Figure G2009101074143D00085
To time domain
Figure G2009101074143D00086
Do and disturb and the noise elimination, obtain
Figure G2009101074143D00087
Figure G2009101074143D00088
h ~ ~ m ( n ) = h ~ m ( n ) n ≤ L w 0 n > L w , l CPThe length of expression Cyclic Prefix (CP);
Will
Figure G2009101074143D000810
Do Fourier transform (FFT) to frequency domain;
M/S with the pilot frequency locations that is extracted iIndividual some channel estimation in frequency domain realized other (M-M/S with the mode of interpolation i) the individual pilot tone point channel estimating that is not drawn into, obtain the M point channel estimation in frequency domain value of pilot frequency locations.
Non-pilot symbol channel estimation module 1032 carries out channel estimating to non-pilot symbol, and the channel estimation in frequency domain of pilot frequency locations is realized with the mode of filtering the channel estimating that non-pilot symbol is put.
The description that Fig. 2 is exemplary the flow process of channel estimation methods of the present invention, it comprises:
Step S201: the frequency domain resource N that judgement user m takies RB, mWhether less than default number of resource blocks, if so, make S i=S (1), execution in step S204; If not, execution in step S202.
Step S202: judge whether the mode bit in link-quality status register R has 0, if make S i=S (1), execution in step S204; If not, execution in step S203;
Step S203: judgement extracting multiple level status register T, not identical if the sampling grade in register T has, make S i=S i-1If the grade in register T is entirely identical, make S iBe S i-1Grade put forward higher leveled extracting multiple, and upgrade extracting multiple level status register;
S204: the frequency domain data D that extracts the corresponding sub-carrier positions of targeted customer m in the frequency domain data that receives mBy M continuous pilot sub-carrier of frequency domain corresponding to the targeted customer who receives, obtaining length is the reception frequency domain demodulation reference mark Y of M m(k), k=1 ..., M;
S205: to Y m(k), k=1 ..., M carries out S iDoubly extract, obtaining length is M/S iThe reception frequency domain demodulation reference mark
Figure G2009101074143D00091
K=1 ..., M/S i
S206: generate the pilot demodulated reference symbol in this locality according to the mode of transmitting terminal, and transform to frequency domain X m(k), and to X m(k) carry out S iDoubly extract, obtaining length is M/S iLocal frequency domain demodulation reference mark
Figure G2009101074143D00092
K=1 ..., M/S i
At step S207 to S208: calculate the pilot bit channel estimation value, the channel estimation in frequency domain value of pilot frequency locations is realized with filtering mode the channel estimating that non-pilot symbol is put.
At step S209 to S210: link-quality is judged and the renewal of sliding.
Referring to Fig. 3, for the channel estimating shown in step S207 to S208, its concrete step comprises:
Step S301 to S302: the channel estimation in frequency domain value of calculating the demodulation reference mark that extracts
Figure G2009101074143D00093
Figure G2009101074143D00101
K=1 ..., M/S i
Step S303: will
Figure G2009101074143D00102
Do inversefouriertransform (IFFT) to time domain
Figure G2009101074143D00103
Step S304: to time domain
Figure G2009101074143D00104
Do and disturb and the noise elimination;
Figure G2009101074143D00105
h ~ ~ m ( n ) = h ~ m ( n ) n ≤ L w 0 n > L w , l CPThe length of expression Cyclic Prefix (CP);
Step S305: will
Figure G2009101074143D00107
Do Fourier transform (FFT) to frequency domain;
Step S306: with the M/S of the pilot frequency locations that is extracted iIndividual some channel estimation in frequency domain realized other (M-M/S with the mode of interpolation i) the individual pilot tone point channel estimating that is not drawn into, obtain the M point channel estimation in frequency domain of pilot frequency locations; The channel estimation in frequency domain of pilot frequency locations is realized with the mode of filtering the channel estimating that non-pilot symbol is put.
Referring to Fig. 4, Fig. 4 shows the pilot frequency locations schematic diagram of the SC-FDMA PUSCH of system channel demodulation reference signal, and the below is elaborated to the method for channel estimating and channel post-processing as an example of the PUSCH channel example.
Following technical scheme is described for user m, and all user's adaptive channel estimation schemes are identical.If C max=3, S (1)＜S (2)＜S (3) makes S (1)=1, S (2)=2, S (3)=3.
If the frequency resource that judgement user m takies less than default number of resource blocks, is just done extracting multiple and is 1 channel estimating, when extracting multiple is 1, equals the uplink receiving demodulation reference mark not to be done extraction, directly carries out conventional channel estimating;
If greater than default number of resource blocks, judge according to L uplink quality before this user the multiple that this receiving demodulation reference symbol is extracted again, mode bit in link-quality status register R has 0, the extracting multiple grade of demodulated reference signal is S (1) so, extracting multiple is 1, does not namely do extraction; If the mode bit complete 1 in link-quality status register R, see again the state of extracting multiple level status register T, if each flag is different grade, keep so a nearest sampling grade constant, if be all same effective grade, just the sampling grade with this improves a rank, and the sampling rank remains unchanged after reaching the superlative degree.
The default number of resource blocks of acquiescence is relevant with modulation system and the characteristic of channel, can obtain by emulation, provides default value in embodiment:
AWGN EPA EVA
QPSK 5 15 25
16QAM 5 20 30
64QAM 5 25 50
Extract the frequency domain data D of the corresponding sub-carrier positions of targeted customer m in the frequency domain data that receives m, D mAccount for M subcarrier.
Then extract M continuous pilot sub-carrier of frequency domain on physical location corresponding to the targeted customer receive, obtain the frequency domain demodulation reference mark Y that length is M m(k), k=1 ..., M.
To Y m(k), k=1 ..., M carries out 3 times and (establishes the flag that the mode bit in R is in 1, T and be S 2, this extracting multiple upgrades to S 3) extract, obtaining length is the reception frequency domain demodulation reference mark of M/3
Figure G2009101074143D00111
K=1 ..., M/3;
Generate the pilot demodulated reference symbol in this locality according to the mode of transmitting terminal, and transform to frequency domain X m(k), and to X m(k) carry out 3 times of extractions, obtain
Figure G2009101074143D00112
Calculate the channel estimation in frequency domain value
Figure G2009101074143D00113
Figure G2009101074143D00114
Will
Figure G2009101074143D00115
Transform to time domain N=1 ..., M/3,
Figure G2009101074143D00117
K=1 ..., M/3;
The efficient channel impulse response window that calculates the targeted customer is long
Figure G2009101074143D00118
(calculating as an example of normal CP length example);
Filtering channel estimation window external noise, h ~ ~ m ( n ) = h ~ m ( n ) n ≤ L w 0 n > L w ;
Will be through the channel estimation value of channel post-processing
Figure G2009101074143D001110
Transform to frequency domain;
Figure G2009101074143D001111
k＝1，…，M/3，n＝1，…，M/3，
M/3 some channel estimation in frequency domain of the pilot frequency locations that is extracted realized the individual pilot tone point channel estimating that are not drawn into of other 2M/3 with the mode of interpolation, obtain the M point channel estimation in frequency domain H of pilot frequency locations m(k), k=1 ..., M;
Channel estimation in frequency domain H with pilot frequency locations M, slot0(k), H M, slot1(k) (subscript slot0, slot1 represent respectively the pilot bit of time slot 0 and time slot 1), k=1 ..., M realizes with the mode of filtering the channel estimating that non-pilot symbol is put.
Calculate the signal to noise ratio of this receive data, or the calculated data Block Error Rate, or it is combined to form specific index as the link-quality measurement index, as the signal to noise ratio with receive data, according to the user data signal to noise ratio of this execution, slide and upgrade link-quality status register R
If signal to noise ratio is better than set point, R M, i=[r 2r 3R L1];
If signal to noise ratio is not better than set point, R M, i=[r 2r 3R L0], wherein, subscript m identifying user m, i are expressed as the i secondary channel and estimate (current channel estimating).
Main purpose of the present invention is to provide a kind ofly can according to the frequency domain resource of CU size and this user chain quality, come self adaptation to reduce the channel estimating apparatus of complexity.the realization of this device is in the SC-FDMA system, by and real-time link-quality big or small according to the CU frequency domain resource, decide the density that the demodulated reference signal sequence is extracted, and demodulated reference signal is extracted, utilize the demodulated reference signal after extracting to do to received signal the channel estimating of pilot frequency locations at frequency domain, the channel estimation in frequency domain of pilot frequency locations is realized with the mode of filtering the channel estimating that non-pilot symbol is put, thereby complete SC-FDMA system channel characteristic estimating, and this link-quality is exported to this user's channel estimating next time, decide the density that the demodulated reference signal sequence is extracted with this link-quality, thereby realize adaptive reduction channel estimating complexity process.Adopt this self adaptation of the present invention to reduce channel estimating apparatus and the method for complexity, the channel estimation calculation amount is approximately reduced to original 1/S, reduces to process time-delay, reduces system loading, and reduces hardware cost, improves running efficiency of system.
The present invention is applicable to SC-FDMA system and ofdm system, any have signal and process, and the engineer of the knowledge background such as communication can design according to the present invention corresponding device, any modification of doing, be equal to replacement, improvement etc., it all should be included in thought of the present invention and scope.

Claims (8)

1. a channel estimation methods, is characterized in that, comprises the steps:
A, the default two-stage extracting multiple at least of extracting multiple judge module are dynamically determined current extracting multiple according to link-quality as follows,
A1, judge that whether the frequency domain resource of CU is less than default number of resource blocks; In this way, determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, carry out next step;
A2, judge whether current link-quality is up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, heighten step by step current extracting multiple;
B, pilot tone abstraction module extract receiving frequency domain demodulation reference mark and local frequency domain demodulation reference mark according to described current extracting multiple;
C, channel estimation module are by calculating current channel estimation in frequency domain value through reception frequency domain demodulation reference mark and the local frequency domain demodulation reference mark that extracts.
2. channel estimation methods as claimed in claim 1, is characterized in that, described steps A 2 is further carried out as follows:
Judge that whether link-quality continues in time period recently up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, carry out next step;
Judge that historical extracting multiple is whether identical in time period recently, in this way, determine that current extracting multiple is the high one-level extracting multiple of historical extracting multiple, otherwise, determine that current extracting multiple is extracting multiple last time.
3. channel estimation methods as claimed in claim 1, it is characterized in that, in described step C, channel estimation module calculates current channel estimation in frequency domain value by the reception frequency domain demodulation reference mark of passing through extraction and local frequency domain demodulation reference mark to carry out as follows:
C1, by the channel estimation in frequency domain value that calculates the pilot tone point that is drawn into through the reception frequency domain demodulation reference mark that extracts and local frequency domain demodulation reference mark;
The channel estimation in frequency domain value of C2, the pilot tone point that obtained not being drawn into by the channel estimation in frequency domain value of the pilot tone point that is drawn into;
C3, obtained the channel estimation value of non-pilot tone point by the channel estimation in frequency domain value of pilot tone point.
4. channel estimation methods as claimed in claim 3, is characterized in that, the frequency domain estimated value of the described pilot tone point that is drawn into comprises following processing: its interference and noise that carries out in time domain is eliminated.
5. channel estimation methods as claimed in claim 3, is characterized in that, in described step C3, obtained the channel estimation value employing filtering mode of non-pilot tone point by the channel estimation in frequency domain value of pilot tone point.
6. channel estimation methods as claimed in claim 1, is characterized in that, in described steps A 2, judging that current link-quality is whether up to standard carries out as follows:
Default link-quality value up to standard determines that the link-quality measurement index whether greater than default link-quality value up to standard, in this way, determines that link-quality is up to standard; Otherwise link-quality is not up to standard; Wherein, described link-quality measurement index comprises signal to noise ratio, Block Error Rate or the signal to noise ratio of receive data and the combination of Block Error Rate.
7. a channel estimating apparatus, is characterized in that, comprising:
Extracting multiple judge module: be used for default two-stage extracting multiple at least, dynamically determine current extracting multiple according to link-quality; Described extracting multiple judge module comprises frequency domain resource judging unit and link-quality judging unit up to standard, wherein, and frequency domain resource judging unit: be used for judging that whether the frequency domain resource of CU is less than default number of resource blocks; In this way, determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, transfer to link-quality judging unit up to standard and continue judgement;
Link-quality judging unit up to standard: be used for judging whether current link-quality is up to standard, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, heighten step by step current extracting multiple;
Pilot tone abstraction module: be used for according to described current extracting multiple, extract receiving frequency domain demodulation reference mark and local frequency domain demodulation reference mark;
Channel estimation module: be used for by calculating current channel estimation in frequency domain value through reception frequency domain demodulation reference mark and the local frequency domain demodulation reference mark that extracts.
8. channel estimating apparatus as claimed in claim 7, is characterized in that, link-quality judging unit up to standard comprises that link-quality continues judging unit up to standard and historical extracting multiple judging unit, wherein:
Link-quality continues judging unit up to standard: be used for judge that link-quality is whether lasting up to standard in time period recently, as not being to determine that current extracting multiple is the lowermost level extracting multiple; Otherwise, transfer to historical extracting multiple judging unit and continue judgement;
Historical extracting multiple judging unit: be used for judging that historical extracting multiple is whether identical in time period recently, in this way, determine that current extracting multiple is the high one-level extracting multiple of historical extracting multiple, otherwise, determine that current extracting multiple is extracting multiple last time.
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