CN101741771A - Channel estimation method and device - Google Patents

Abstract

The invention discloses channel estimation method and device. The device comprises a control module, a scattered pilot extracting module, a time domain interpolation module and an FIR (Finite Impulse Response) filter module, wherein the control module is used for storing input OFDM (Orthogonal Frequency Division Multiplexing) symbol data into an OFDM data buffer area of a channel estimating device; the scattered pilot extracting module is used for storing the scattered pilot of each OFDM symbol data, which is obtained from the OFDM symbol data stored in the OFDM data buffer area; the time domain interpolation module is used for reading the scattered pilot of the adjacent OFDM symbol from a scattered pilot buffer area and storing the scattered pilot after carrying out time domain linear interpolation processing into the scattered pilot buffer area; and the FIR filter module is used for obtaining a filter coefficient from a filter coefficient buffer area, obtaining the scattered pilot after time domain linear interpolation processing from the scattered pilot buffer area, carrying out FIR filter calculation according to the obtained filter coefficient and the scattered pilot and outputting a channel estimating result. The invention can favorably meet the requirement of the CMMB (China Mobile Multimedia Broadcasting) standard channel estimation processing function.

Description

Channel estimation methods and device

Technical field

The present invention relates to the communications field, in particular to a kind of channel estimation methods and device.

Background technology

China Mobile's DMB (China Mobile MultimediaBroadcasting, abbreviate CMMB as) system be utilize high-power S-band satellite-signal cover nationwide, utilize ground supplement translator with frequently simultaneously with content repeater satellite signal, mend point and cover the satellite-signal blind area, utilize mobile radio networks to make up return path, form the mobile media broadcasting network that One-to-All Broadcast and two-way interactive combine.

The broadcast channel physical layer bandwidth of CMMB standard definition comprises 8MHz and two kinds of options of 2MHz.Physical layer signal was 1 frame in per 1 second, was divided into 40 time slots.The length of each time slot is 25ms, comprises 1 beacon and 53 OFDMs (OrthogonalFrequency Division Multiplexing abbreviates OFDM as) symbol.

The formation of frequency-domain OFDM symbol be by with data subcarrier and scattered pilot with continuous pilot multiple connection be in the same place, form the OFDM frequency domain symbol, wherein, each OFDM symbol comprises Nv effectively subcarrier, under the 8MHz pattern, the value of Nv is 3076.

Write down in each time slot on n the OFDM symbol i effectively subcarrier be Xn (i), i=0,1 ..., Nv-1; 0≤n≤52.Fig. 1 is the schematic diagram of data subcarrier, scattered pilot and the continuous pilot method of salary distribution according to correlation technique, and the effective subcarrier allocation that shows the OFDM symbol as Fig. 1 is the method for salary distribution of data subcarrier, scattered pilot and continuous pilot.

Continuous pilot is to transmit the subcarrier of identical information on each OFDM symbol of same time slot.When Bf=8MHz, comprise 82 continuous pilot in each OFDM symbol.The position of continuous pilot in the OFDM symbol is as shown in table 1.

Under the table 18MHz pattern, the position of continuous pilot in the OFDM symbol

	?Bf＝8MHz
		Continuous pilot	?0，22，78，92，168，174，244，274，278，?344，382，424，426，496，500，564，608，650，?688，712，740，772，846，848，932，942，950，?980，1012，1066，1126，1158，1214，1244，1276，?1280，1326，1378，1408，1508，1537，1538，?1566，1666，1736，1748，1794，1798，1830，?1860，1916，1948，2008，2062，2094，2124，?2132，2142，2226，2228，2302，2334，2362，?2386，2424，2466，2510，2574，2578，2648，?2650，2692，2730，2796，2800，2830，2900，?2906，2982，2996，3052，3075

Each continuous pilot adopts binary phase shift keying (Binary Phase Shift Key, abbreviating BPSK as) modulation system transmits 1 bit information, the BPSK modulation system as shown in Figure 2, wherein, partial continuous pilot tone (position sees Table 2) is used to transmit 16 bit transfer indication informations, and all the other continuous pilot transmit fixed bit " 0 ".

The position that is used for the continuous pilot of system information under the table 28MHz pattern

Bit	??Bf＝8MHz
		??0	??22、650、1860、2466
??1	??78、688、1916、2510
		??2	??92、712、1948、2574
??3	??168、740、2008、2578
		??4	??174、772、2062、2648
??5	??244、846、2094、2650
		??6	??274、848、2124、2692
??7	??278、932、2132、2730
		??8	??344、942、2142、2796
??9	??382、950、2226、2800
		??10	??424、980、2228、2830
??11	??426、1012、2302、2900
		??12	??496、1066、2334、2906
??13	??500、1126、2362、2982
		??14	??564、1158、2386、2996
??15	??608、1214、2424、3052

Scattered pilot sends known symbol 1+0j, in each time slot in the 1st OFDM symbol effective subcarrier number m value rule of scattered pilot correspondence as follows:

Bf＝8MHz：

if(mod(1，2)＝＝0)

$m=\left\{\begin{array}{cc}8p+1,& p=\mathrm{0,1,2},...,191\\ 8p+3,& p=\mathrm{192,193,194},...,383\end{array}\right.$

if(mod(1，2)＝＝1)

$m=\left\{\begin{array}{cc}8p+5,& p=\mathrm{0,1,2},...,191\\ 8p+7,& p=\mathrm{192,193,194},...,383\end{array}\right.$

Because there are a series of complicated phenomenons such as multipath, Doppler effect, noise and interference in channel, therefore, when receiving the CMMB signal, in order to guarantee the quality of reception, channel estimating just becomes an indispensable processing procedure.

In correlation technique,, following several method is arranged generally for channel estimating:

(1) ratio method, this method realizes simple, but noise inhibiting ability is poor.

(2) linear least mean-square poor (Linear Minimum Mean Square Error abbreviates LMMSE as) method, this method has noise suppressed preferably, but needs the statistical property of channel and noise, realizes complicated.

(3) time domain correlation method, this method has noise suppressed preferably, but operand is bigger.

Therefore, because there is above-mentioned defective in present channel estimation methods, can not satisfy the CMMB system to needs simple in structure, low in resources consumption, that realize performance such as easy.

Summary of the invention

The defective that exists at present channel estimation methods can not satisfy the CMMB system problem of needs simple in structure, low in resources consumption, as to realize performance such as easy is proposed the present invention, for this reason, the present invention aims to provide a kind of channel estimation methods and device, to address the above problem.

According to an aspect of the present invention, provide a kind of channel estimating apparatus.

Channel estimating apparatus according to the present invention comprises: control module, and the orthogonal frequency division multiplex OFDM symbol data that is used for importing stores the OFDM data buffer zone of channel estimating apparatus into; The scattered pilot extraction module is used for obtaining the scattered pilot of each OFDM symbol data from the OFDM symbol data of OFDM data buffer area storage, and the scattered pilot that obtains is stored into the scattered pilot buffering area of channel estimating apparatus; The time domain interpolation module is used for reading from the scattered pilot buffering area scattered pilot of adjacent OFDM symbol, carry out the time domain linear interpolation processing, and the scattered pilot that will carry out after the time domain linear interpolation processing stores the scattered pilot buffering area into; Limit for length's impulse response FIR filtration module is arranged, be used for obtaining filter factor from the filter coefficient buffering area of channel estimating apparatus, obtain scattered pilot after the time domain linear interpolation processing from the scattered pilot buffering area, carry out FIR filtering according to the filter factor that obtains and scattered pilot and calculate and the delivery channel estimated result.

Preferably, control module also is used to dispatch scattered pilot extraction module, time domain interpolation module, FIR filtration module, OFDM data buffer area, scattered pilot buffering area, filter coefficient buffering area.

Preferably, the OFDM data buffer zone comprises two random access memory rams.

Carry out ping-pong operation when preferably, the OFDM data buffer zone is used for the OFDM symbol data stored.

Preferably, the scattered pilot extraction module is used for directly extracting scattered pilot or converting the continuous pilot the OFDM symbol data of OFDM data buffer area storage to scattered pilot from the OFDM symbol data of OFDM data buffer area storage.

Preferably, the scattered pilot buffering area comprises three block RAMs.

Preferably, the filter coefficient buffering area comprise be used for according to time slot to the input filter factor carry out ping-pong operation/following two and half districts.

According to an aspect of the present invention, provide a kind of channel estimation methods.

According to channel estimation methods of the present invention, be applied to China Mobile's digital multimedia broadcasting system, comprise the steps: from OFDM input data, to obtain the scattered pilot of the adjacent OFDM symbol of current OFDM symbol, and scattered pilot is carried out the time domain linear interpolation processing; Carry out filtering according to scattered pilot after the time domain linear interpolation processing and the filter factor that obtains and calculate, obtain channel estimation results.

Preferably, importing the scattered pilot that obtains the adjacent OFDM symbol of current OFDM symbol the data from OFDM comprises: the scattered pilot that directly extracts the adjacent OFDM symbol of current OFDM symbol from OFDM input data; The continuous pilot of OFDM being imported the adjacent OFDM symbol of current OFDM symbol in the data converts scattered pilot to.

Preferably, scattered pilot being carried out the time domain linear interpolation processing comprises: the scattered pilot of the adjacent OFDM symbol of current OFDM symbol is carried out arithmetic average.

Preferably, before carrying out filtering calculating, said method also comprises: the subcarrier between two adjacent discrete pilot tones of same OFDM symbol is carried out zero insertion handle.

By the present invention, control module in the channel estimating apparatus is saved to the OFDM data buffer zone with it after receiving OFDM input data, extract the scattered pilot of this symbol then, and the startup interpolating module carries out time domain interpolation, dispatching the FIR filtration module at last calculates and the delivery channel estimated result, the defective that has solved present channel estimation methods existence can not satisfy the CMMB system to simple in structure, low in resources consumption, realize the problem of the needs of performance such as easy, apparatus structure provided by the invention is simple, the hardware resource service efficiency is high and be easy to realization, can satisfy the needs that the CMMB standard channel is estimated processing capacity well.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 is the schematic diagram of data subcarrier, scattered pilot and the continuous pilot method of salary distribution according to correlation technique;

Fig. 2 is the schematic diagram according to the BPSK constellation mapping of correlation technique;

Fig. 3 is the structured flowchart according to the channel estimating apparatus of the embodiment of the invention;

Fig. 4 is the schematic diagram according to the channel estimation works flow process of the embodiment of the invention;

Fig. 5 is the OFDM0 buffering area use schematic diagram according to the embodiment of the invention;

Fig. 6 is the OFDM1 buffering area use schematic diagram according to the embodiment of the invention;

Fig. 7 is the OFDM51 buffering area use schematic diagram according to the embodiment of the invention;

Fig. 8 is the OFDM52 buffering area use schematic diagram according to the embodiment of the invention;

Fig. 9 is the schematic diagram according to the FIR filter construction of the embodiment of the invention;

Figure 10 is the flow chart according to the channel estimation methods of the embodiment of the invention.

Embodiment

Functional overview

Consider that the defective that present channel estimation methods exists can not satisfy the CMMB system to simple in structure, low in resources consumption, realize the problem of the needs of performance such as easy, the embodiment of the invention provides a kind of channel estimation methods and device, can be applied to the pattern of CMMB standard 8MHz bandwidth, determine channel estimating according to scattered pilot information known in the transmission signals, in above-mentioned channel estimating apparatus, control module is saved to the OFDM data buffer zone with it after receiving OFDM input data, extract the scattered pilot of this symbol then, and start interpolating module and carry out time domain interpolation, dispatch the FIR filtration module at last and calculate and the delivery channel estimated result.

Need to prove that under the situation of not conflicting, embodiment and the feature among the embodiment among the application can make up mutually.Describe the present invention below with reference to the accompanying drawings and in conjunction with the embodiments in detail.

Device embodiment

According to embodiments of the invention, a kind of channel estimating apparatus is provided, this device is used to realize the channel estimating of CMMB standard.Fig. 3 is the structured flowchart according to the channel estimating apparatus of the embodiment of the invention, as shown in Figure 3, this device comprises: control module 2, scattered pilot extraction module 4, time domain interpolation module 6, limit for length's impulse response (Finite ImpulseResponse abbreviates FIR as) filtration module 8 is arranged, below said structure is described.

Control module 2, the OFDM symbol data that is used for importing stores the OFDM data buffer zone of channel estimating apparatus into; Control module 2 also is used for dispatching each module of this channel estimating apparatus, includes but not limited to lower module: scattered pilot extraction module, time domain interpolation module, FIR filtration module, OFDM data buffer area, scattered pilot buffering area, filter coefficient buffering area.

Scattered pilot extraction module 4 is used for obtaining the scattered pilot of each OFDM symbol data from the OFDM symbol data of OFDM data buffer area storage, and the scattered pilot that obtains is stored into the scattered pilot buffering area of channel estimating apparatus;

Particularly, scattered pilot extraction module 4 scattered pilot that obtains each OFDM symbol data comprises following dual mode:

(1) from the OFDM symbol data of OFDM data buffer area storage, directly extracts scattered pilot.

(2) convert the continuous pilot in the OFDM symbol data of OFDM data buffer area storage to scattered pilot.

Time domain interpolation module 6 is used for reading from the scattered pilot buffering area scattered pilot of adjacent OFDM symbol, carry out the time domain linear interpolation processing, and the scattered pilot that will carry out after the time domain linear interpolation processing stores the scattered pilot buffering area into.

FIR filtration module 8, be used for obtaining filter factor from the filter coefficient buffering area of channel estimating apparatus, obtain scattered pilot after (reading) time domain linear interpolation processing from the scattered pilot buffering area, carry out FIR filtering according to the filter factor that obtains and scattered pilot and calculate and the delivery channel estimated result.

This channel estimating apparatus also comprises following buffering area: OFDM data buffer zone 1, scattered pilot buffering area 3, filter coefficient buffering area 5 are described each buffering area below.

OFDM data buffer zone 1 comprises two random asccess memory (Random AccessMemory abbreviates RAM as), carries out ping-pong operation when according to the scheduling of control module the OFDM symbol data being stored.

Scattered pilot buffering area 3 comprises 3 block RAMs, and this 3 block RAM structure unanimity recycles, and every block RAM is preserved this symbol scattered pilot, and the average of adjacent-symbol scattered pilot.

Filter coefficient buffering area 5, that is, a block RAM is divided into/following two and half districts, according to time slot the filter factor of importing is carried out ping-pong operation, and preserves the filter factor of this time slot.

In addition, this channel estimating apparatus can also comprise: top-level module 0, be responsible for integrated input/output interface, inner each module and the RAM of this device.

Pattern at CMMB standard 8MHz bandwidth is described in conjunction with the implementation procedure of above-mentioned channel estimating apparatus to the embodiment of the invention below.

Fig. 4 is the schematic diagram according to the channel estimation works flow process of the embodiment of the invention, and as shown in Figure 4, system enters IDLE (free time) 0 state after receiving the reset reset signal; If receive the start enabling signal, then enter SAVE (that is, the storage of OFDM symbol data) 1 state, otherwise continue to keep idle condition.

After entering the SAVE state, an OFDM symbol data of importing is saved in the OFDM data buffer zone, the SAVE state finishes to enter PEXT (scattered pilot extraction) 2 states after (save_over).

After entering the PEXT state, extract the scattered pilot of current sign and deposit the scattered pilot buffering area in, then convert continuous pilot subcarrier 1537,3075 to scattered pilot, deposit the scattered pilot buffering area in the lump in.If current is the scattered pilot that extracts OFDM0, owing to there are not the OFDM1 data, can not carry out the time domain linear interpolation, so the PEXT state turns back to the IDLE state after finishing according to the scattered pilot of adjacent-symbol; Otherwise the PEXT state finishes to transfer to PINS (time domain interpolation) 3 states after (pext_over).

After entering the PINS state, according to the average of adjacent-symbol scattered pilot, carry out the time domain linear interpolation, obtain the input of 4 times of interpolation FIR of this symbol filter, the PINS state enters FILT (filtering) 4 states after finishing (pins_over).

After entering the FILT state, read scattered pilot and filter coefficient after the linear interpolation, carry out FIR filtering and calculate, the channel estimation results after output is calculated.Filtering finish the back if current be that OFDM51 is carried out filtering, because OFDM52 time domain linear interpolation need be OFDM51 as adjacent-symbol, so need transfer to the PEXT state, extract the scattered pilot of OFDM51 again and cover the deposit position of scattered pilot buffering area OFDM50; Otherwise return the IDLE idle condition.

The OFDM data buffer zone is made up of two block RAMs, carries out ping-pong operation, preserves indicator register ofdm_save_num by data and indicates that current is the input data of preserving which OFDM symbol.The scattered pilot buffering area is made up of 3 block RAMs, recycles, and extracts indicator register ofdm_pext_num by scattered pilot and determines that current is the scattered pilot that extracts which OFDM symbol.Describe the occupation mode of buffering area in detail below with reference to Fig. 5, Fig. 6, Fig. 7 and Fig. 8.

Fig. 5 is the OFDM0 buffering area use schematic diagram according to the embodiment of the invention, as shown in Figure 5, after first symbol OFDM 0 data of time slot are preserved, starting scattered pilot extracts, after having extracted the scattered pilot of OFDM0, so also do not have the scattered pilot of adjacent-symbol at this moment can't carry out filtering owing to current, control module turns back to idle condition and waits for next symbol initial signal.

Fig. 6 is the OFDM1 buffering area use schematic diagram according to the embodiment of the invention, as shown in Figure 6, when extracting the scattered pilot of OFDM1, it need be write simultaneously scattered pilot buffer RAM piece buffer b and buffer c, like this follow-up when carrying out the time domain linear interpolation, can directly use interpolating module to finish time domain linear interpolation to OFDM0.

Fig. 7 uses schematic diagram according to the OFDM51 buffering area of the embodiment of the invention, as shown in Figure 7, behind the scattered pilot that extracts OFDM52, asks for the scattered pilot average of OFDM50 and OFDM52 and is inserted into the scattered pilot buffer RAM of OFDM51.

Fig. 8 is the OFDM52 buffering area use schematic diagram according to the embodiment of the invention, as shown in Figure 8, after end is calculated in OFDM51 filtering, control module turns back to scattered pilot and extracts state, again extract the scattered pilot of OFDM51 and store buffer c into, carry out the filtering input that the time domain linear interpolation obtains OFDM52 then.

Fig. 9 is the schematic diagram according to the FIR filter construction of the embodiment of the invention, as shown in Figure 9, in order to save hardware resource, the FIR filter adopts flowing structure, I, the multiplexing complex multiplier of Q two paths of data, accumulator is responsible for each complex multiplication result is added up, and exports the channel estimation results after the saturated processing at last.

According to scattered pilot position formula as can be seen, if the channel estimation results of all subcarriers of output, then follow-up separating when shining upon need be carried out the judgement of four kinds of situations for the scattered pilot subcarrier.According to table 2 as can be known, numbering 0,1537,1538,3075 these four continuous pilot do not comprise system information, if remove this four continuous pilot during channel estimating output, then effective subcarrier number m value rule of the scattered pilot correspondence of n OFDM symbol is reduced in each time slot:

if?mod(n，2)＝＝0

m＝8p

if?mod(n，2)＝＝1

m＝8p+4

Based on above-mentioned consideration, for each OFDM symbol, only export 1～1536 and 1539～3074 channel estimation results of totally 3072 subcarriers, can simplify the difficulty of subsequent treatment like this and save resource.

Method embodiment

According to embodiments of the invention, a kind of channel estimation methods is provided, be applied to the CMMB system, this method can realize in conjunction with above-mentioned channel estimating apparatus.Figure 10 is the flow chart according to the channel estimation methods of the embodiment of the invention, and as shown in figure 10, this method comprises following step S102 and step S104, and concrete operations are as follows:

Step S102 imports the scattered pilot that obtains the adjacent OFDM symbol of current OFDM symbol the data from OFDM, and scattered pilot is carried out the time domain linear interpolation processing; The time domain linear interpolation processing here is meant that the scattered pilot with the adjacent OFDM symbol of current OFDM symbol carries out arithmetic average.

Wherein, import the scattered pilot that obtains the adjacent OFDM symbol of current OFDM symbol the data from OFDM and comprise following dual mode:

(1) imports the scattered pilot that directly extracts the adjacent OFDM symbol of current OFDM symbol the data from OFDM.

(2) continuous pilot of OFDM being imported the adjacent OFDM symbol of current OFDM symbol in the data converts scattered pilot to.

Step S104 carries out filtering according to scattered pilot after the time domain linear interpolation processing and the filter factor that obtains and calculates, and obtains channel estimation results; Before carrying out filtering calculating, need carry out zero insertion to the subcarrier between two adjacent discrete pilot tones of same OFDM symbol and handle.

By this embodiment, according to the scattered pilot of current OFDM symbol, use its adjacent OFDM symbol scattered pilot to carry out linear interpolation in time domain, adopt 4 times of interpolations, the variable FIR filters of coefficient to realize the channel estimating of CMMB system at frequency domain.

Below in conjunction with example the implementation procedure that realizes channel estimating under the CMMB standard 8MHz bandwidth mode is described.

At first, convert continuous pilot subcarrier 1537 and 3075 to scattered pilot;

${\mathrm{HP}}_l\left(k\right)=C_l\left(k\right)\·\frac{\sqrt{2}}{2}(1-j)$ k＝1037，3075

Then scattered pilot is carried out time domain interpolation, particularly, utilize the scattered pilot of former and later two OFDM symbols carry out arithmetic average obtain current sign the time domain interpolation result (that is, above-mentioned step S102) at corresponding subcarrier place;

HP _l(k)＝(HP _l-1(k)+HP _l+1(k))/2

K value rule is as follows:

if(mod(1，2)＝＝0)

$k=\left\{\begin{array}{ccc}8p+5,& p=\mathrm{0,1,2},...,191& 0\≤k\≤1537\\ 8p+1543,& p=\mathrm{0,1,2},...,191& 1538\≤k\≤3075\end{array}\right.$

if(mod(1，2)＝＝1)

$k=\left\{\begin{array}{ccc}8p+1,& p=\mathrm{0,1,2},...,191& 0\≤k\≤1537\\ 8p+1540,& p=\mathrm{0,1,2},...,191& 1538\≤k\≤3075\end{array}\right.$

Through behind the time domain interpolation, the interval in OFDM symbol between former and later two adjacent pilot frequencies is 4 subcarriers, it is carried out 4 times of zero insertions handle and obtain HP _l(m);

if(0≤m≤1537)

${\mathrm{HP}}_l\left(m\right)=\left\{\begin{array}{cc}{\mathrm{HP}}_l\left(k\right),& m=4k+1\\ 0,& m\≠4k+1\end{array}\right.$

if(1538≤m≤3075)

${\mathrm{HP}}_l\left(m\right)=\left\{\begin{array}{cc}{\mathrm{HP}}_l\left(k\right),& m=4k+1539\\ 0,& m\≠4k+1539\end{array}\right.$

Then to HP _l(m) carry out the FIR Filtering Processing that filter factor is Coef (n), can obtain the channel estimation results after the interpolation (that is, above-mentioned step S104).

$\widehat{{\mathrm{HP}}_l\left(m\right)}=\underset{n=1}{\overset{q}{\mathrm{\Σ}}}\mathrm{Coef}\left(n\right)\·{\mathrm{HP}}_l(m-n)$

By the above embodiment of the present invention, the channel estimation methods of time domain linear interpolation, frequency domain interpolation filtering has been proposed, it is realized simple and can satisfy the needs of CMMB system on performance.Recycling of the ping-pong operation of OFDM data buffer zone and scattered pilot buffering area saved the expense of hardware RAM resource effectively.Filter coefficient is that unit is kept among the special-purpose RAM with the time slot, can adjust performance of filter neatly according to the actual state of channel like this.The FIR filter adopts pipeline mode, and multiplexing multiplier has been saved hardware resource.Remove four useless continuous pilot during the delivery channel estimated result, simplified the follow-up mapping processing of separating.In sum, channel estimation methods provided by the invention and apparatus structure are simple, and the hardware resource service efficiency is high and be easy to realization, can satisfy the needs that the CMMB standard channel is estimated processing capacity well.

Obviously, those skilled in the art should be understood that, above-mentioned each module of the present invention or each step can realize with the general calculation device, they can concentrate on the single calculation element, perhaps be distributed on the network that a plurality of calculation element forms, alternatively, they can be realized with the executable program code of calculation element, thereby, they can be stored in the storage device and carry out by calculation element, perhaps they are made into each integrated circuit modules respectively, perhaps a plurality of modules in them or step are made into the single integrated circuit module and realize.Like this, the present invention is not restricted to any specific hardware and software combination.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (11)

1. a channel estimating apparatus is characterized in that, comprising:

Control module, the orthogonal frequency division multiplex OFDM symbol data that is used for importing stores the OFDM data buffer zone of described channel estimating apparatus into;

The scattered pilot extraction module be used for obtaining the scattered pilot of each OFDM symbol data from the described OFDM symbol data of described OFDM data buffer area storage, and the described scattered pilot that will obtain stores the scattered pilot buffering area of described channel estimating apparatus into;

The time domain interpolation module is used for reading from described scattered pilot buffering area the scattered pilot of adjacent OFDM symbol, carry out the time domain linear interpolation processing, and the scattered pilot that will carry out after the time domain linear interpolation processing stores described scattered pilot buffering area into;

Limit for length's impulse response FIR filtration module is arranged, be used for obtaining filter factor from the filter coefficient buffering area of described channel estimating apparatus, obtain scattered pilot after the described time domain linear interpolation processing from described scattered pilot buffering area, carry out FIR filtering according to the described filter factor that obtains and described scattered pilot and calculate and the delivery channel estimated result.

2. device according to claim 1, it is characterized in that described control module also is used to dispatch described scattered pilot extraction module, described time domain interpolation module, described FIR filtration module, described OFDM data buffer area, described scattered pilot buffering area, described filter coefficient buffering area.

3. device according to claim 1 is characterized in that, described OFDM data buffer zone comprises two random access memory rams.

4. device according to claim 1 is characterized in that, carries out ping-pong operation when described OFDM data buffer zone is used for the storage of described OFDM symbol data.

5. device according to claim 1, it is characterized in that described scattered pilot extraction module is used for directly extracting scattered pilot or converting the continuous pilot the described OFDM symbol data of described OFDM data buffer area storage to scattered pilot from the described OFDM symbol data of described OFDM data buffer area storage.

6. device according to claim 1 is characterized in that, described scattered pilot buffering area comprises three block RAMs.

7. device according to claim 1 is characterized in that, described filter coefficient buffering area comprise be used for according to time slot to the input filter factor carry out ping-pong operation/following two and half districts.

8. a channel estimation methods is applied to China Mobile's digital multimedia broadcasting system, it is characterized in that, described method comprises:

From OFDM input data, obtain the scattered pilot of the adjacent OFDM symbol of current OFDM symbol, and described scattered pilot is carried out the time domain linear interpolation processing;

Carry out filtering according to described scattered pilot after the time domain linear interpolation processing and the filter factor that obtains and calculate, obtain channel estimation results.

9. method according to claim 8 is characterized in that, the scattered pilot that obtains the adjacent OFDM symbol of current OFDM symbol from OFDM input data comprises:

From described OFDM input data, directly extract the scattered pilot of the adjacent OFDM symbol of described current OFDM symbol;

The continuous pilot of described OFDM being imported the adjacent OFDM symbol of current OFDM symbol described in the data converts scattered pilot to.

10. method according to claim 8 is characterized in that, described scattered pilot is carried out the time domain linear interpolation processing comprise:

The scattered pilot of the adjacent OFDM symbol of described current OFDM symbol is carried out arithmetic average.

11. method according to claim 8 is characterized in that, before carrying out filtering calculating, described method also comprises:

Subcarrier between two adjacent discrete pilot tones of same OFDM symbol is carried out zero insertion to be handled.

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