CN107248967A - A kind of channel estimation methods and device applied to ofdm system - Google Patents
A kind of channel estimation methods and device applied to ofdm system Download PDFInfo
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- CN107248967A CN107248967A CN201610579107.5A CN201610579107A CN107248967A CN 107248967 A CN107248967 A CN 107248967A CN 201610579107 A CN201610579107 A CN 201610579107A CN 107248967 A CN107248967 A CN 107248967A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/06—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
- H04L25/061—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a kind of channel estimation methods and device applied to ofdm system, belong to wireless communication technology field, every frame data of ofdm system transmission include M training sequence and N number of OFDM symbol, each OFDM symbol includes P data subcarrier and Q pilot sub-carrier, frequency response of this channel estimation methods based on training sequence respectively at pilot sub-carrier and at data subcarrier, obtain the weight of first OFDM symbol, again using " being used as weight with the difference of the frequency response at pilot sub-carrier at data subcarrier ", preserve the changing rule between subcarrier, calculating is iterated successively asks frequency response of each OFDM symbol at data subcarrier, solve and carry out ofdm system channel estimation currently with interpolation algorithm, the technical problem of time selective fading caused by being difficult to resist Doppler frequency shift when recovering frequency response, this programme can effectively antagonize certain Doppler frequency shift, so as to improve the accuracy of channel estimation, reduce the bit error rate.
Description
Technical field
The present invention relates to wireless communication technology field, more particularly to a kind of channel estimation methods applied to ofdm system and
Device.
Background technology
With the progress in epoch, developing rapidly for mobile communication particularly cellular cell makes user thoroughly break away from terminal and set
Standby constraint, realize complete personal mobility, reliable transmission means and continuation method.Into 21 century, mobile communication will
It is gradually evolved into social development and progressive essential instrument.
At present, the development course of mobile communication technology is as follows：1) the first Generation Mobile Communication System (1G) standard formulation is in 20
The eighties in century, it is the system for being only limitted to voice communication.Because 1G is realized based on analog circuit, therefore its stability has
Limit, communication quality can not be completely secured, and it mainly uses frequency multiplexing technique, and broadband utilization rate is very low, be not suitable for working as
The rare situation of preceding frequency spectrum.2) second generation mobile communication system (2G) originates from the 1990s, 2G standards start to use number
Word technology, substantially increases the stability and reliability of system.3) 3-G (Generation Three mobile communication system) (3G) in developing in recent years
Come, 3G technology has increased to a new height relative to preceding two generation technique, but 3G technology can not provide broadband many matchmakers
The application of body business.Therefore in communication system of new generation (4G), high-speed, high-quality and diversified data service are research
One of emphasis.
In past wireless communication system, usually using single carrier transmission, this transmission means is in speed compared with Gao Shihui
Cause intersymbol interference (ISI, Inter Symbol Interference) because channel width is excessive.And orthogonal frequency division multiplexing
Carrier wave is divided into multiple subcarriers with (OFDM, Orthogonal Frequency Division Multiplexing) technology,
Make after packet to transmit on each subcarrier, the bandwidth of so each subcarrier can be very small, less than coherence bandwidth, can be with
Reduce ISI.In addition, to select suitable carrier wave interval to cause orthogonal between each subcarrier for OFDM technology, and adjacent carrier is in frequency
It is overlapping on domain, improves band efficiency.Therefore OFDM technology with its high transfer rate, high spectrum utilization and effectively it is right
The technical advantages such as mitigating frequency-selective fading signal, as 4G communications, WLAN (WLAN, Wireless Local Area
Newworks), Wireless Personal Network (WPAN, Wireless Personal Area Network) and the key technology of broadcast.Its
In, 4G communications include Long Term Evolution plan (LTE, Long Term Evolution) and the worldwide interoperability for microwave accesses of 4G standards
(WiMAX, Worldwide Interoperability for Microwave Access) (i.e. 802.16 wireless MANs)；
WLAN includes Institute of Electrical and Electric Engineers (IEEE, Institute of Electrical an Electronics
Engineers) the 802.11a/g/n agreements of standard；Broadcast includes digital audio broadcasting (DAB, Digital Audio
) and DVB (DVB, Digital Video Broadcasting) Broadcasting.
When known to the frequency domain response of channel, on the premise of additive noise influence is not considered, pass through frequency domain equalization, OFDM
The influence of multipath channel can be completely eliminated in receiver.But, in most of OFDM receivers, the information of channel is unknown
's.Need to estimate channel in the relevant detection of ofdm system；Specifically, channel estimation mainly has three steps：Estimation, is inserted
Value and equilibrium.Wherein, " estimation " is to utilize pilot tone, gone with the pilot frequency information of receiving terminal divided by transmitting terminal pilot frequency information, come
To the frequency response of channel；" interpolation " is that the frequency for recovering whole subcarriers using the frequency response at pilot tone with interpolation algorithm is rung
Answer (being equally estimate)；" equilibrium " is the signal divided by the frequency response that recovers using the reception of receiving terminal, is just obtained
Send the estimate of end signal.The precision of channel estimation will directly affect the performance of whole ofdm system.
Channel estimation is carried out to ofdm system by the following two kinds of programs in the prior art：
Scheme one：Using linear interpolation algorithm, the response estimation value to former and later two pilot tone frequencies of OFDM channels is carried out
Estimation obtains the frequency response of the channel.But, this method is only with the channel estimation value of two adjacent pilot frequency locations, interpolation
Obtain the channel response at the data carrier between two pilot tones.Its basis assumes that each data between adjacent pilot frequencies channel
The transfer function of subchannel be according to certain slope linear change, and receiving terminal have higher translational speed movement lead to
In letter system, have due to time selective fading caused by Doppler frequency shift (in the system Doppler frequency shift 180Hz with
It is interior), linear interpolation precision is not high.
Scheme two：Using Gauss interpolation algorithm (i.e. quadratic interpolation algorithm), led using subchannel data and its forward and backward three
The response of frequency channel is estimated.But, this method complexity is very high and confrontation time selective fading indifferent.
That is, existing in the prior art：Ofdm system channel estimation is carried out using interpolation algorithm, is rung recovering frequency
Seasonable to be difficult to time selective fading caused by confrontation Doppler frequency shift, precision of channel estimation is not high, and error rate of system is not excellent enough
The technical problem of change.
The content of the invention
The present invention is recovering frequency for present in prior art, ofdm system channel estimation is carried out using interpolation algorithm
Rate is difficult to time selective fading caused by confrontation Doppler frequency shift when responding, precision of channel estimation is not high, and error rate of system is not
The technical problem enough optimized can effectively antagonize one there is provided a kind of channel estimation methods and device applied to ofdm system
Determine Doppler frequency shift, so as to improve the accuracy of channel estimation, reduce the bit error rate.
On the one hand, the invention provides a kind of channel estimation methods applied to ofdm system, the ofdm system is used for
Every frame data of transmission include M training sequence and N number of OFDM symbol, and M is that positive integer, N are integer more than or equal to 2, wherein,
Each OFDM symbol includes P data subcarrier and Q pilot sub-carrier, the channel estimation side in N number of OFDM symbol
Method comprises the following steps：
S1, by minimum variance principle algorithm, obtain first frequency response and i-th of second frequency response, wherein, i according to
The secondary round numbers on 1~N of interval, first frequency response for the M training sequence frequency response, described i-th the
Two frequency responses are frequency of i-th of OFDM symbol at Q pilot sub-carrier included by itself in N number of OFDM symbol
Response；
S2, based on first frequency response, obtain the 3rd frequency response and the 4th frequency response, and based on the described 3rd
Frequency response and the 4th frequency response, obtain the first weight；Wherein, the 3rd frequency response rings for the first frequency
Frequency response in answering at P data subcarrier of correspondence, the 4th frequency response is corresponding Q in first frequency response
Frequency response at pilot sub-carrier；
S3, the i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, based on the i-th weight and described i-th
Second frequency is responded, and obtains i-th of the 5th frequency responses, and i-th weight is entered based on i-th of the 5th frequency responses
Row updates, to obtain i+1 weight, until when i values are N-1, obtaining N weights；Wherein, i-th of the 5th frequencies are rung
It should be frequency response of i-th of the OFDM symbol at P data subcarrier included by itself；
S4, responded based on the N weights and n-th second frequency, obtain the frequency response of n-th the 5th；
S5, by receiving signal divided by the frequency response of the n-th the 5th, obtain the n-th estimation frequency for sending signal
Response.
Optionally, first weight is specially the difference of the 3rd frequency response and the 4th frequency response.
Optionally, i-th of second frequency response, including：I-th of pilot amplitude frequency response and i-th of pilot tone phase
Bit frequency is responded；Wherein, i-th of pilot amplitude frequency response is Q pilot tone of i-th of OFDM symbol included by itself
Amplitude-frequency response at subcarrier, i-th of pilot phase frequency response is i-th of OFDM symbol included by itself
Phase-frequency response at Q pilot sub-carrier；The step S3 is specifically included：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, is led based on the i-th weight and described i-th
Frequency amplitude-frequency response, obtains i-th of data amplitude frequency response；Meanwhile, based on the i-th weight and i-th of pilot phase
Frequency response, obtains i-th of data phase frequency response；Wherein, i-th of data amplitude frequency response is described i-th
Amplitude-frequency response of the OFDM symbol at P data subcarrier included by itself, i-th of data phase frequency response
For phase-frequency response of i-th of the OFDM symbol at P data subcarrier included by itself；
Obtained based on i-th of data amplitude frequency response, i-th of data phase frequency response and public formula (I)
I-th of the 5th frequency responses；Wherein, public formula (I) is expressed as：E is the bottom of natural logrithm
Number, j is imaginary unit；
I-th weight is updated based on i-th of the 5th frequency responses, to obtain i+1 weight, until i
When value is N-1, N weights are obtained.
Optionally, in the step S3：The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, is based on
I-th weight and i-th of second frequency response, obtain i-th of the 5th frequency responses, are specially：
Make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, pass through the i-th weight and described i-th the
Two frequency responses are summed, to obtain i-th of the 5th frequency responses.
Optionally, in the step S3, i-th weight is updated based on i-th of the 5th frequency responses, with
I+1 weight is obtained, is specifically included：
By receiving signal divided by i-th of the 5th frequency responses, obtain corresponding with i-th of the 5th frequency responses
Transmission signal i-th of estimated frequency response；
Hard decision is carried out to i-th of estimated frequency response, to obtain i-th of hard decision frequency response；
By receiving signal divided by i-th of hard decision frequency response, i-th of revised frequency response is obtained；
Ask poor by i-th of revised frequency response and i-th of second frequency response, i-th weight is entered
Row updates, to obtain i+1 weight.
On the other hand, present invention also offers a kind of channel estimating apparatus applied to ofdm system, the ofdm system
Every frame data for transmission include M training sequence and N number of OFDM symbol, and M is that positive integer, N are integer more than or equal to 2,
Wherein, each OFDM symbol includes P data subcarrier and Q pilot sub-carrier in N number of OFDM symbol, and the channel is estimated
Counter device includes：
Training sequence and pilot carrier frequency response acquiring unit, for by minimum variance principle algorithm, obtaining first frequency
Response and i-th of second frequency response, wherein, the i round numbers on 1~N of interval successively, the first frequency response is the M
The frequency response of individual training sequence, i-th of second frequency response exists for i-th of OFDM symbol in N number of OFDM symbol
The frequency response at Q pilot sub-carrier included by itself；
First Weight Acquisition unit, for based on first frequency response, obtaining the 3rd frequency response and the 4th frequency
Response, and based on the 3rd frequency response and the 4th frequency response, obtain the first weight；Wherein, the 3rd frequency
The frequency response at P data subcarrier of correspondence in being responded for the first frequency is responded, the 4th frequency response is described
Frequency response in first frequency response at Q pilot sub-carrier of correspondence；
Weight updating block, for making the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on i-th
Weight and i-th of second frequency response, obtain i-th of the 5th frequency responses, and based on i-th of the 5th frequency responses
I-th weight is updated, to obtain i+1 weight, until when i values are N-1, obtaining N weights；Wherein, it is described
I-th of the 5th frequency responses are frequency response of i-th of the OFDM symbol at P data subcarrier included by itself；
Frequency response acquiring unit at OFDM symbol data subcarrier, for based on the N weights and the frequency of n-th second
Rate is responded, and obtains the frequency response of n-th the 5th；
Final estimated frequency response acquiring unit, for by receiving signal divided by the frequency response of the n-th the 5th, obtaining
The n-th estimated frequency response of signal must be sent.
Optionally, first weight is specially the difference of the 3rd frequency response and the 4th frequency response.
Optionally, i-th of second frequency response, including：I-th of pilot amplitude frequency response and i-th of pilot tone phase
Bit frequency is responded；Wherein, i-th of pilot amplitude frequency response is Q pilot tone of i-th of OFDM symbol included by itself
Amplitude-frequency response at subcarrier, i-th of pilot phase frequency response is i-th of OFDM symbol included by itself
Phase-frequency response at Q pilot sub-carrier；The weight updating block is specifically included：
Amplitude-phase frequency acquisition module, for making the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value,
Based on the i-th weight and i-th of pilot amplitude frequency response, i-th of data amplitude frequency response is obtained；Meanwhile, based on i-th
Weight and i-th of pilot phase frequency response, obtain i-th of data phase frequency response；Wherein, i-th of data
Amplitude-frequency response is amplitude-frequency response of i-th of the OFDM symbol at P data subcarrier included by itself, institute
I-th of data phase frequency response is stated for phase of i-th of the OFDM symbol at P data subcarrier included by itself
Frequency response；
Frequency response acquisition module at digital subcarrier, for based on i-th of data amplitude frequency response, described
I data phase-frequency response and public formula (I) obtain i-th of the 5th frequency responses；Wherein, public formula (I) is expressed as：E is the truth of a matter of natural logrithm, and j is imaginary unit；
Weight update module, for being updated based on i-th of the 5th frequency responses to i-th weight, to obtain
I+1 weight is obtained, until when i values are N-1, obtaining N weights.
Optionally, the weight updating block is used to make the i round numbers on 1~N-1 of interval successively, and takes a fixed value in i
When, responded based on the i-th weight and i-th of second frequency, obtain i-th of the 5th frequency responses, particularly for：
Make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, pass through the i-th weight and described i-th the
Two frequency responses are summed, to obtain i-th of the 5th frequency responses.
Optionally, the weight updating block is used to carry out i-th weight based on i-th of the 5th frequency responses
Update, to obtain i+1 weight, specifically including is used for：
By receiving signal divided by i-th of the 5th frequency responses, obtain corresponding with i-th of the 5th frequency responses
Transmission signal i-th of estimated frequency response；
Hard decision is carried out to i-th of estimated frequency response, to obtain i-th of hard decision frequency response；
By receiving signal divided by i-th of hard decision frequency response, i-th of revised frequency response is obtained；
Ask poor by i-th of revised frequency response and i-th of second frequency response, i-th weight is entered
Row updates, to obtain i+1 weight.
The one or more technical schemes provided in the present invention, have at least the following technical effects or advantages：
Due in the present invention, by using intrinsic in ofdm system communication protocol, known training sequence and pilot tone
Frequency response, estimating frequency response of the OFDM symbol at data subcarrier in the frame data to be transmitted, and thus
To the estimate of primary signal.Efficiently solve and carry out ofdm system channel estimation using interpolation algorithm in the prior art,
Recover to be difficult to time selective fading caused by confrontation Doppler frequency shift during frequency response, precision of channel estimation is not high, and system is missed
The technical problem that code check not enough optimizes, realizes and is believed in the case of environment relatively severe (Doppler frequency shift is less than 180Hz)
Estimate with balanced to reduce the bit error rate of system in road.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the accompanying drawing used required in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
The embodiment of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis
The accompanying drawing of offer obtains other accompanying drawings.
Fig. 1 is the matrix sequence schematic diagram of the frame data provided in an embodiment of the present invention transmitted based on ofdm system；
Fig. 2 is a kind of channel estimation methods flow chart applied to ofdm system provided in an embodiment of the present invention；
Fig. 3 is a kind of channel estimating apparatus structured flowchart applied to ofdm system provided in an embodiment of the present invention；
Fig. 4 is another channel estimating apparatus structured flowchart applied to ofdm system provided in an embodiment of the present invention.
Embodiment
The embodiment of the present invention is solved in the prior art by providing a kind of channel estimation methods applied to ofdm system
Exist, ofdm system channel estimation is carried out using interpolation algorithm, confrontation Doppler frequency shift is difficult to when recovering frequency response and is led
The time selective fading of cause, precision of channel estimation is not high, the technical problem that error rate of system not enough optimizes.Using this programme energy
Certain Doppler frequency shift is enough effectively antagonized, so as to improve the accuracy of channel estimation, the bit error rate is reduced.
The technical scheme of the embodiment of the present invention is in order to solve the above technical problems, general thought is as follows：
The embodiments of the invention provide a kind of channel estimation methods applied to ofdm system, the ofdm system is used to pass
Defeated every frame data include M training sequence and N number of OFDM symbol, and M is that positive integer, N are integer more than or equal to 2, wherein, institute
Stating each OFDM symbol in N number of OFDM symbol includes P data subcarrier and Q pilot sub-carrier, the channel estimation methods
Comprise the following steps：S1, by minimum variance principle algorithm, obtain first frequency response and i-th of second frequency response, its
In, the i round numbers on 1~N of interval successively, first frequency response for the M training sequence frequency response, described the
I second frequency response is i-th of OFDM symbol in N number of OFDM symbol at Q pilot sub-carrier included by itself
Frequency response；S2, based on first frequency response, obtain the 3rd frequency response and the 4th frequency response, and based on described
3rd frequency response and the 4th frequency response, obtain the first weight；Wherein, the 3rd frequency response is the described first frequency
Frequency response in rate response at P data subcarrier of correspondence, the 4th frequency response is right during the first frequency is responded
Answer the frequency response at Q pilot sub-carrier；S3, make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, base
Responded in the i-th weight and i-th of second frequency, obtain i-th of the 5th frequency responses, and based on described i-th the 5th frequencies
Rate response is updated to i-th weight, to obtain i+1 weight, until when i values are N-1, obtaining N weights；Its
In, i-th of the 5th frequency responses are frequency of i-th of the OFDM symbol at P data subcarrier included by itself
Rate is responded；S4, responded based on the N weights and n-th second frequency, obtain the frequency response of n-th the 5th；S5, by connecing
The collection of letters number divided by the frequency response of the n-th the 5th, obtain the n-th estimated frequency response for sending signal.
It can be seen that, in the present invention program, by using intrinsic in ofdm system communication protocol, known training sequence and
The frequency response of pilot tone, to estimate frequency response of the OFDM symbol at data subcarrier in the frame data to be transmitted, and by
This obtains the estimate of primary signal.Efficiently solve and estimated in the prior art using interpolation algorithm progress ofdm system channel
Meter, time selective fading caused by confrontation Doppler frequency shift is difficult to when recovering frequency response, and precision of channel estimation is not high, is
The technical problem that the system bit error rate not enough optimizes, realizes and enters in the case of environment relatively severe (Doppler frequency shift is less than 180Hz)
Row channel estimation and equalization is to reduce the bit error rate of system.
In order to be better understood from above-mentioned technical proposal, below in conjunction with Figure of description and specific embodiment to upper
State technical scheme to be described in detail, it should be understood that the specific features in the embodiment of the present invention and embodiment are to the application
The detailed description of technical scheme, rather than the restriction to technical scheme, in the case where not conflicting, the present invention is implemented
Technical characteristic in example and embodiment can be mutually combined.
Embodiment one
Fig. 1 and Fig. 2 are refer to, the embodiments of the invention provide a kind of channel estimation methods applied to ofdm system, institute
State ofdm system be used for transmit every frame data include M training sequence (A1~AM) and N number of OFDM symbol (B1~BN), M is just
Integer, N are the integer more than or equal to 2, wherein, N number of OFDM symbol (B1~BN) in each OFDM symbol include P data
Subcarrier (C1~CP) and Q pilot sub-carrier (D1~DQ), the channel estimation methods comprise the following steps：
S1, pass through minimum variance principle (LS, Least Squared) algorithm, obtain first frequency response (HLTS) and i-th
Individual second frequency responds (Hpilot_i), wherein, the i round numbers on 1~N of interval successively, the first frequency responds (HLTS) for institute
The frequency response of M training sequence is stated, i-th of second frequency responds (Hpilot_i) it is i-th in N number of OFDM symbol
Frequency response of the OFDM symbol at Q pilot sub-carrier included by itself；
Specifically, according to the difference of the host-host protocol of ofdm system, its P data for transmitting each OFDM symbol is carried
The specific number and arrangement mode of ripple and Q pilot sub-carrier are also different.For example, using in 802.11a/g it is intrinsic,
Known training sequence and pilot tone obtain frequency response, and obtain by frequency response the estimate of primary signal；802.11a/g
In define to have in a frame and have 64 subcarriers in 2 training sequences, each OFDM symbol, in this 64 subcarriers, 48
Subcarrier sends the information subcarrier (being referred to as data subcarrier) of information for only carrying, and 4 subcarriers are known pilot tone
Carrier wave, other 12 subcarriers are zero subcarrier.Fig. 1 is only that the P data subcarrier and Q for being directed to its certain host-host protocol are led
The arrangement mode of frequency subcarrier, understands for convenience, and special concentrate Q pilot sub-carrier is arranged under P data subcarrier
Side.
In the host-host protocol of ofdm system, intrinsic, known training sequence and pilot sub-carrier are generally included, is trained
The frequency response of sequence and pilot sub-carrier can be obtained by calculating.In the present embodiment, calculated and obtained using LTS algorithms
First frequency responds (HLTS) (correspondence training sequence) and i-th of second frequency response (Hpilot_i) (correspondence pilot sub-carrier).By
Include Q pilot sub-carrier (D in each OFDM symbol1~DQ), therefore, for N number of OFDM symbol, make i successively in interval 1
The upper round numbers of~N, you can try to achieve the second frequency response corresponding to each OFDM symbol in N number of OFDM symbol
(Hpilot_i)。
S2, based on the first frequency respond (HLTS), obtain the 3rd frequency response (HLTS_data) and the 4th frequency response
(HLTS_pilot), and based on the 3rd frequency response (HLTS_data) and the 4th frequency response (HLTS_pilot), obtain first
Weight (w1)；Wherein, the 3rd frequency response (HLTS_data) respond (H for the first frequencyLTS) in P data of correspondence it is sub
Frequency response at carrier wave, the 4th frequency response (HLTS_pilot) respond (H for the first frequencyLTS) in correspondence Q lead
Frequency response at frequency subcarrier；
Specifically, Fig. 1 is referred to, first frequency response (HLTS) the correspondence separator bar L left sides M longitudinal direction sequence (A1~
AM), the 3rd frequency response (HLTS_data) respond (H for first frequencyLTS) in P data subcarrier of correspondence (i.e. transverse direction sequence C '1
~C'P) place frequency response, the 4th frequency response (HLTS_pilot) respond (H for first frequencyLTS) in correspondence Q pilot tone son load
Ripple (i.e. horizontal sequence D '1~D'Q) place frequency response.
S3, make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on the i-th weight (wi) and it is described
I-th of second frequency responds (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), and based on described i-th the 5th frequencies
Rate responds (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), until when i values are N-1,
Obtain N weights (wN)；Wherein, i-th of the 5th frequency response (Hdata_i) it is i-th of OFDM symbol in itself institute
Including P data subcarrier at frequency response；
S4, based on the N weights (wN) and n-th second frequency response (Hpilot_N), obtain the frequency of n-th the 5th and ring
Answer (Hdata_N)；
S5, by receiving signal (Y) divided by the frequency response (H of the n-th the 5thdata_N), obtain the N for sending signal
Individual estimated frequency response (Xest_N)。
In specific implementation process, LS algorithms can be represented simply as lower formula (II) in step S1：
In upper formula (II), HLSCorrespondence first frequency response (HLTS) or i-th of second frequency response (Hpilot_i), YLSIt is to connect
Training sequence signal or pilot signal that receiving end is received, XLSIt is training sequence signal or pilot signal that transmitting terminal is sent.
In step s 2, the first weight (w1) it is specially the 3rd frequency response (HLTS_data) and the described 4th frequency
Rate responds (HLTS_pilot) difference.It is represented by following formula (III)：
w1=HLTS_data-HLTS_pilot (III)
In formula (III), weight w1Actually in order to preserve changing rule of the training sequence on frequency domain.Due to adjacent
OFDM symbol is varied less in the changing rule of frequency domain, therefore can be replaced by previous OFDM symbol in the changing rule of frequency domain
Change of the previous OFDM symbol on frequency domain.Therefore can be by above by training sequence at pilot sub-carrier and at data subcarrier
Frequency response (HLTS_pilot、HLTS_data) the first weight w for trying to achieve1, it is used as N number of OFDM symbol (B1~BN) in the 1st
The weight of OFDM symbol.
Further, because the transmission signal (Signal) of ofdm system is complex signal, you can be expressed as amplitude and phase is negative
Shown in the form of index, such as following formula (IV)：
Signal=AejP (IV)
In formula (IV), A represents amplitude, and P represents phase, and e is the truth of a matter of natural logrithm, and j is imaginary unit.In step S3
In, i-th of weight (wi) it is used to calculate the frequency for obtaining i-th of OFDM symbol at P data subcarrier included by itself
Response, when the transmission signal of channel is time multiplexed signal, i-th of weight (wi) it is segmented into amplitude weight and phase weights.
Corresponding, i-th of second frequency responds (Hpilot_i), including：I-th of pilot amplitude frequency response
(Apilot_i) and i-th of pilot phase frequency response (Ppilot_i)；Wherein, i-th of pilot amplitude frequency response (Apilot_i)
For amplitude-frequency response of i-th of OFDM symbol at Q pilot sub-carrier included by itself, i-th of pilot phase
Frequency response (Ppilot_i) it is phase-frequency response of i-th of OFDM symbol at Q pilot sub-carrier included by itself；Institute
Step S3 is stated to specifically include：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, based on the i-th weight (wi) amplitude weight
With i-th of pilot amplitude frequency response (Apilot_i), obtain i-th of data amplitude frequency response (Adata_i)；Meanwhile, base
In the i-th weight (wi) phase weights and i-th of pilot phase frequency response (Ppilot_i), obtain i-th of data phase frequency
Rate responds (Pdata_i)；Wherein, i-th of data amplitude frequency response (Adata_i) for i-th of OFDM symbol at itself
Amplitude-frequency response at P included data subcarrier, i-th of data phase frequency response (Pdata_i) it is described
Phase-frequency response of i-th of OFDM symbol at P data subcarrier included by itself；
Based on i-th of data amplitude frequency response (Adata_i), i-th of data phase frequency response (Pdata_i)
I-th of the 5th frequency response (H are obtained with public formula (I)data_i)；Wherein, public formula (I) is expressed as：E is the truth of a matter of natural logrithm, and j is imaginary unit；
Based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1
Weight (wi+1), until when i values are N-1, obtaining N weights (wN)。
Further, in specific implementation process, in the step S3：Make the i round numbers on 1~N-1 of interval successively, and
When i takes a fixed value, based on the i-th weight (wi) and i-th of second frequency response (Hpilot_i), obtain i-th the 5th frequencies
Rate responds (Hdata_i), it is specially：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, passes through the i-th weight (wi) and described i-th
Individual second frequency responds (Hpilot_i) summation, to obtain i-th of the 5th frequency response (Hdata_i).Specifically, can be under
Formula (V) is represented：
Hdata_i=wi+Hpilot_i (V)
In addition, in the step S3, based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) enter
Row updates, to obtain i+1 weight (wi+1), specifically include：
By receiving signal (Y) divided by i-th of the 5th frequency response (Hdata_i), obtain and described i-th the 5th frequencies
Rate responds (Hdata_i) corresponding i-th of estimated frequency response (X for sending signalest_i)；
To i-th of estimated frequency response (Xest_i) hard decision is carried out, to obtain i-th of hard decision frequency response
(XHD_i)；Wherein, " hard decision " is to i-th of estimated frequency response (Xest_i) be first demodulated, then be modulated, have
Shown in body such as following formula (VI)：
XHD_i=mod (demod (Xest_i)) (VI)
Further, by receiving signal (Y) divided by i-th of hard decision frequency response (XHD_i), obtain i-th of amendment
Frequency response afterwards
Pass through i-th of revised frequency response(H is responded with i-th of second frequencypilot_i) ask poor,
To the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), shown in formula (VII) specific as follows：
In brief, step S3 central idea is：(1) with i-th weight (w corresponding with i-th of OFDM symboli) ask
Frequency response (H of i-th of OFDM symbol at P data subcarrier included by itselfdata_i)；(2) frequency response is used
(Hdata_i) the corresponding frequency response (X for sending signal of estimationest_i)；(3) it is based on frequency response (Xest_i) corrected
Frequency response afterwards(4) revised frequency response is usedUpdate the i-th weight (wi), and obtain i+1
Weight (wi+1).Wherein, the i round numbers on 1~N-1 of interval successively.Until when i values are N-1, obtaining N weights (wN)。
Further, then step S5 is performed, to obtain n-th estimated frequency response (Xest_N), i.e., channel final estimation frequency
Rate is responded.
Sum it up, application scheme, is primarily based on training sequence respectively at pilot sub-carrier and at data subcarrier
Frequency response, the weight of first OFDM symbol is obtained, then using " frequency response and pilot sub-carrier at data subcarrier
The difference of the frequency response at place is used as weight ", the changing rule between subcarrier is preserved, calculating is iterated successively and asks each OFDM to accord with
Frequency response number at data subcarrier, solves and carries out ofdm system channel estimation using interpolation algorithm in the prior art,
It is difficult to time selective fading caused by confrontation Doppler frequency shift when recovering frequency response, precision of channel estimation is not high, system
The technical problem that the bit error rate not enough optimizes, this programme can be effective against the caused time selective fading of receiving terminal movement and many
Frequency selective fading caused by the effect of footpath, so as to improve the accuracy of channel estimation, reduces the bit error rate.
Embodiment two
Based on same inventive concept, Fig. 3 is refer to, the embodiment of the present invention additionally provides a kind of letter applied to ofdm system
Road estimation unit, every frame data that the ofdm system is used to transmit include M training sequence and N number of OFDM symbol, and M is just whole
Number, N are the integer more than or equal to 2, wherein, each OFDM symbol includes P data subcarrier and Q in N number of OFDM symbol
Individual pilot sub-carrier, the channel estimating apparatus includes：
Training sequence and pilot carrier frequency response acquiring unit 31, for by minimum variance principle algorithm, obtaining the first frequency
Rate responds (HLTS) and i-th of second frequency response (Hpilot_i), wherein, i round numbers, described first on 1~N of interval successively
Frequency response (HLTS) be the M training sequence frequency response, i-th of second frequency response (Hpilot_i) it is the N
Frequency response of i-th of OFDM symbol at Q pilot sub-carrier included by itself in individual OFDM symbol；
First Weight Acquisition unit 32, for responding (H based on the first frequencyLTS), obtain the 3rd frequency response
(HLTS_data) and the 4th frequency response (HLTS_pilot), and based on the 3rd frequency response (HLTS_data) and the 4th frequency
Respond (HLTS_pilot), obtain the first weight (w1)；Wherein, the 3rd frequency response (HLTS_data) rung for the first frequency
Answer (HLTS) in correspondence P data subcarrier at frequency response, the 4th frequency response (HLTS_pilot) it is the described first frequency
Rate responds (HLTS) in correspondence Q pilot sub-carrier at frequency response；
Weight updating block 33, for making the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on the
I weights (wi) and i-th of second frequency response (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), and based on institute
State i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), until
When i values are N-1, N weights (w is obtainedN)；Wherein, i-th of the 5th frequency response (Hdata_i) it is i-th of OFDM
Frequency response of the symbol at P data subcarrier included by itself；
Frequency response acquiring unit 34 at OFDM symbol data subcarrier, for based on the N weights (wN) and n-th
Second frequency responds (Hpilot_N), obtain the frequency response (H of n-th the 5thdata_N)；
Final estimated frequency response acquiring unit 35, for being rung by receiving signal (Y) divided by the frequency of the n-th the 5th
Answer (Hdata_N), obtain the n-th estimated frequency response (X for sending signalest_N)。
In specific implementation process, the first weight (w1) it is specially the 3rd frequency response (HLTS_data) with it is described
4th frequency response (HLTS_pilot) difference.
In specific implementation process, i-th of second frequency responds (Hpilot_i), including：I-th of pilot amplitude frequency
Respond (Apilot_i) and i-th of pilot phase frequency response (Ppilot_i)；Wherein, i-th of pilot amplitude frequency response
(Apilot_i) it is amplitude-frequency response of i-th of OFDM symbol at Q pilot sub-carrier included by itself, described i-th
Pilot phase frequency response (Ppilot_i) it is phase frequency of i-th of OFDM symbol at Q pilot sub-carrier included by itself
Rate is responded；The weight updating block 33 is specifically included：
Amplitude-phase frequency acquisition module 331, a fixed value is taken for making the i round numbers on 1~N-1 of interval successively, and in i
When, based on the i-th weight (wi) and i-th of pilot amplitude frequency response (Apilot_i), obtain i-th of data amplitude frequency and ring
Answer (Adata_i)；Meanwhile, based on the i-th weight (wi) and i-th of pilot phase frequency response (Ppilot_i), obtain i-th of number
According to phase-frequency response (Pdata_i)；Wherein, i-th of data amplitude frequency response (Adata_i) accorded with for i-th of OFDM
Amplitude-frequency response number at P data subcarrier included by itself, i-th of data phase frequency response
(Pdata_i) it is phase-frequency response of i-th of the OFDM symbol at P data subcarrier included by itself；
Frequency response acquisition module 332 at digital subcarrier, for based on i-th of data amplitude frequency response
(Adata_i), i-th of data phase frequency response (Pdata_i) and public formula (I) obtain i-th of the 5th frequency responses
(Hdata_i)；Wherein, public formula (I) is expressed as：E is the truth of a matter of natural logrithm, and j is imaginary number list
Position；
Weight update module 333, for based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi)
It is updated, to obtain i+1 weight (wi+1), until when i values are N-1, obtaining N weights (wN)。
In specific implementation process, the weight updating block 33 is used to make the i round numbers on 1~N-1 of interval successively, and
When i takes a fixed value, based on the i-th weight (wi) and i-th of second frequency response (Hpilot_i), obtain described i-th the 5th
Frequency response (Hdata_i), particularly for：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, passes through the i-th weight (wi) and described i-th
Individual second frequency responds (Hpilot_i) summation, to obtain i-th of the 5th frequency response (Hdata_i)。
In specific implementation process, the weight updating block 33 is used to be based on i-th of the 5th frequency responses
(Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), specifically including is used for：
By receiving signal (Y) divided by i-th of the 5th frequency response (Hdata_i), obtain and described i-th the 5th frequencies
Rate responds (Hdata_i) corresponding i-th of estimated frequency response (X for sending signalest_i)；
To i-th of estimated frequency response (Xest_i) hard decision is carried out, to obtain i-th of hard decision frequency response
(XHD_i)；
By receiving signal (Y) divided by i-th of hard decision frequency response (XHD_i), obtain i-th of revised frequency
Rate is responded
Pass through i-th of revised frequency response(H is responded with i-th of second frequencypilot_i) ask poor,
To the i-th weight (wi) be updated, to obtain i+1 weight (wi+1)。
As described above, the above-mentioned channel estimating apparatus applied to ofdm system is used to realize above-mentioned channel estimation side
Method, so, the channel estimating apparatus is consistent with one or more embodiments of above-mentioned channel estimation methods, herein just no longer one by one
Repeat.
, but those skilled in the art once know basic creation although preferred embodiments of the present invention have been described
Property concept, then can make other change and modification to these embodiments.So, appended claims are intended to be construed to include excellent
Select embodiment and fall into having altered and changing for the scope of the invention.
Obviously, those skilled in the art can carry out the essence of various changes and modification without departing from the present invention to the present invention
God and scope.So, if these modifications and variations of the present invention belong to the scope of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to comprising including these changes and modification.
Claims (10)
1. a kind of channel estimation methods applied to ofdm system, every frame data that the ofdm system is used to transmit include M
Training sequence and N number of OFDM symbol, M are that positive integer, N are integer more than or equal to 2, wherein, it is each in N number of OFDM symbol
OFDM symbol includes P data subcarrier and Q pilot sub-carrier, it is characterised in that the channel estimation methods include following
Step：
S1, pass through minimum variance principle algorithm, obtain first frequency response (HLTS) and i-th of second frequency response (Hpilot_i),
Wherein, the i round numbers on 1~N of interval successively, the first frequency responds (HLTS) rung for the frequency of the M training sequence
Should, i-th of second frequency responds (Hpilot_i) be N number of OFDM symbol in i-th of OFDM symbol included by itself
Q pilot sub-carrier at frequency response；
S2, based on the first frequency respond (HLTS), obtain the 3rd frequency response (HLTS_data) and the 4th frequency response
(HLTS_pilot), and based on the 3rd frequency response (HLTS_data) and the 4th frequency response (HLTS_pilot), obtain first
Weight (w1)；Wherein, the 3rd frequency response (HLTS_data) respond (H for the first frequencyLTS) in P data of correspondence it is sub
Frequency response at carrier wave, the 4th frequency response (HLTS_pilot) respond (H for the first frequencyLTS) in correspondence Q lead
Frequency response at frequency subcarrier；
S3, make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on the i-th weight (wi) and it is described i-th
Second frequency responds (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), and based on i-th of the 5th frequency responses
(Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), until when i values are N-1, obtaining the
N weights (wN)；Wherein, i-th of the 5th frequency response (Hdata_i) it is P of i-th of the OFDM symbol included by itself
Frequency response at individual data subcarrier；
S4, based on the N weights (wN) and n-th second frequency response (Hpilot_N), obtain the frequency response of n-th the 5th
(Hdata_N)；
S5, by receiving signal (Y) divided by the frequency response (H of the n-th the 5thdata_N), the n-th for obtaining transmission signal is estimated
Count frequency response (Xest_N)。
2. the channel estimation methods of ofdm system are applied to as claimed in claim 1, it is characterised in that first weight
(w1) it is specially the 3rd frequency response (HLTS_data) and the 4th frequency response (HLTS_pilot) difference.
3. the channel estimation methods of ofdm system are applied to as claimed in claim 1, it is characterised in that described i-th second
Frequency response (Hpilot_i), including：I-th of pilot amplitude frequency response (Apilot_i) and i-th of pilot phase frequency response
(Ppilot_i)；Wherein, i-th of pilot amplitude frequency response (Apilot_i) it is Q of i-th of OFDM symbol included by itself
Amplitude-frequency response at individual pilot sub-carrier, i-th of pilot phase frequency response (Ppilot_i) it is i-th of OFDM symbol
Phase-frequency response at Q pilot sub-carrier included by itself；The step S3 is specifically included：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, based on the i-th weight (wi) and i-th of pilot tone
Amplitude-frequency response (Apilot_i), obtain i-th of data amplitude frequency response (Adata_i)；Meanwhile, based on the i-th weight (wi) and institute
State i-th of pilot phase frequency response (Ppilot_i), obtain i-th of data phase frequency response (Pdata_i)；Wherein, described i-th
Individual data amplitude-frequency response (Adata_i) it is width of i-th of the OFDM symbol at P data subcarrier included by itself
Spend frequency response, i-th of data phase frequency response (Pdata_i) it is P of i-th of the OFDM symbol included by itself
Phase-frequency response at individual data subcarrier；
Based on i-th of data amplitude frequency response (Adata_i), i-th of data phase frequency response (Pdata_i) and it is public
Formula (I) obtains i-th of the 5th frequency response (Hdata_i)；Wherein, public formula (I) is expressed as：
E is the truth of a matter of natural logrithm, and j is imaginary unit；
Based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight
(wi+1), until when i values are N-1, obtaining N weights (wN)。
4. the channel estimation methods of ofdm system are applied to as claimed in claim 1, it is characterised in that in the step S3：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, based on the i-th weight (wi) and i-th second frequencies
Rate responds (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), it is specially：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, passes through the i-th weight (wi) and described i-th second
Frequency response (Hpilot_i) summation, to obtain i-th of the 5th frequency response (Hdata_i)。
5. the channel estimation methods of ofdm system are applied to as claimed in claim 1, it is characterised in that in the step S3,
Based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight
(wi+1), specifically include：
By receiving signal (Y) divided by i-th of the 5th frequency response (Hdata_i), obtain and rung with i-th of the 5th frequencies
Answer (Hdata_i) corresponding i-th of estimated frequency response (X for sending signalest_i)；
To i-th of estimated frequency response (Xest_i) hard decision is carried out, to obtain i-th of hard decision frequency response (XHD_i)；
By receiving signal (Y) divided by i-th of hard decision frequency response (XHD_i), obtain i-th of revised frequency response
Pass through i-th of revised frequency response(H is responded with i-th of second frequencypilot_i) ask poor, to institute
State the i-th weight (wi) be updated, to obtain i+1 weight (wi+1)。
6. a kind of channel estimating apparatus applied to ofdm system, every frame data that the ofdm system is used to transmit include M
Training sequence and N number of OFDM symbol, M are that positive integer, N are integer more than or equal to 2, wherein, it is each in N number of OFDM symbol
OFDM symbol includes P data subcarrier and Q pilot sub-carrier, it is characterised in that the channel estimating apparatus includes：
Training sequence and pilot carrier frequency response acquiring unit, for by minimum variance principle algorithm, obtaining first frequency response
(HLTS) and i-th of second frequency response (Hpilot_i), wherein, the i round numbers on 1~N of interval successively, the first frequency rings
Answer (HLTS) be the M training sequence frequency response, i-th of second frequency response (Hpilot_i) it is N number of OFDM
Frequency response of i-th of OFDM symbol at Q pilot sub-carrier included by itself in symbol；
First Weight Acquisition unit, for responding (H based on the first frequencyLTS), obtain the 3rd frequency response (HLTS_data) and
4th frequency response (HLTS_pilot), and based on the 3rd frequency response (HLTS_data) and the 4th frequency response
(HLTS_pilot), obtain the first weight (w1)；Wherein, the 3rd frequency response (HLTS_data) responded for the first frequency
(HLTS) in correspondence P data subcarrier at frequency response, the 4th frequency response (HLTS_pilot) it is the first frequency
Respond (HLTS) in correspondence Q pilot sub-carrier at frequency response；
Weight updating block, for making the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on the i-th weight
(wi) and i-th of second frequency response (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), and based on described i-th
Individual 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1 weight (wi+1), until i values
During for N-1, N weights (w is obtainedN)；Wherein, i-th of the 5th frequency response (Hdata_i) it is i-th of OFDM symbol
Frequency response at P data subcarrier included by itself；
Frequency response acquiring unit at OFDM symbol data subcarrier, for based on the N weights (wN) and the frequency of n-th second
Rate responds (Hpilot_N), obtain the frequency response (H of n-th the 5thdata_N)；
Final estimated frequency response acquiring unit, for by receiving signal (Y) divided by the frequency response of the n-th the 5th
(Hdata_N), obtain the n-th estimated frequency response (X for sending signalest_N)。
7. the channel estimating apparatus of ofdm system is applied to as claimed in claim 6, it is characterised in that first weight
(w1) it is specially the 3rd frequency response (HLTS_data) and the 4th frequency response (HLTS_pilot) difference.
8. the channel estimating apparatus of ofdm system is applied to as claimed in claim 6, it is characterised in that described i-th second
Frequency response (Hpilot_i), including：I-th of pilot amplitude frequency response (Apilot_i) and i-th of pilot phase frequency response
(Ppilot_i)；Wherein, i-th of pilot amplitude frequency response (Apilot_i) it is Q of i-th of OFDM symbol included by itself
Amplitude-frequency response at individual pilot sub-carrier, i-th of pilot phase frequency response (Ppilot_i) it is i-th of OFDM symbol
Phase-frequency response at Q pilot sub-carrier included by itself；The weight updating block is specifically included：
Amplitude-phase frequency acquisition module, for making the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, is based on
I-th weight (wi) and i-th of pilot amplitude frequency response (Apilot_i), obtain i-th of data amplitude frequency response
(Adata_i)；Meanwhile, based on the i-th weight (wi) and i-th of pilot phase frequency response (Ppilot_i), obtain i-th of data
Phase-frequency response (Pdata_i)；Wherein, i-th of data amplitude frequency response (Adata_i) it is i-th of OFDM symbol
Amplitude-frequency response at P data subcarrier included by itself, i-th of data phase frequency response (Pdata_i)
For phase-frequency response of i-th of the OFDM symbol at P data subcarrier included by itself；
Frequency response acquisition module at digital subcarrier, for based on i-th of data amplitude frequency response (Adata_i), institute
State i-th of data phase frequency response (Pdata_i) and public formula (I) obtain i-th of the 5th frequency response (Hdata_i)；Wherein,
Public formula (I) is expressed as：E is the truth of a matter of natural logrithm, and j is imaginary unit；
Weight update module, for based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) carry out more
Newly, to obtain i+1 weight (wi+1), until when i values are N-1, obtaining N weights (wN)。
9. the channel estimating apparatus of ofdm system is applied to as claimed in claim 6, it is characterised in that the weight updates single
Member is used to make the i round numbers on 1~N-1 of interval successively, and when i takes a fixed value, based on the i-th weight (wi) and it is described i-th
Second frequency responds (Hpilot_i), obtain i-th of the 5th frequency response (Hdata_i), particularly for：
The i round numbers on 1~N-1 of interval successively is made, and when i takes a fixed value, passes through the i-th weight (wi) and described i-th second
Frequency response (Hpilot_i) summation, to obtain i-th of the 5th frequency response (Hdata_i)。
10. the channel estimating apparatus of ofdm system is applied to as claimed in claim 6, it is characterised in that the weight updates
Unit is used to be based on i-th of the 5th frequency response (Hdata_i) to the i-th weight (wi) be updated, to obtain i+1
Weight (wi+1), specifically including is used for：
By receiving signal (Y) divided by i-th of the 5th frequency response (Hdata_i), obtain and rung with i-th of the 5th frequencies
Answer (Hdata_i) corresponding i-th of estimated frequency response (X for sending signalest_i)；
To i-th of estimated frequency response (Xest_i) hard decision is carried out, to obtain i-th of hard decision frequency response (XHD_i)；
By receiving signal (Y) divided by i-th of hard decision frequency response (XHD_i), obtain i-th of revised frequency response
Pass through i-th of revised frequency response(H is responded with i-th of second frequencypilot_i) ask poor, to institute
State the i-th weight (wi) be updated, to obtain i+1 weight (wi+1)。
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| CN115189990B (en) * | 2022-06-29 | 2023-05-30 | 南京邮电大学 | OFDM time domain channel prediction method and system based on circulation deposit learning network |
| CN117424784A (en) * | 2023-12-19 | 2024-01-19 | 成都国恒空间技术工程股份有限公司 | OFDM system channel estimation method based on leading and pilot frequency |
| CN117424784B (en) * | 2023-12-19 | 2024-02-23 | 成都国恒空间技术工程股份有限公司 | OFDM system channel estimation method based on leading and pilot frequency |
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