CN1725748A - Measure the method and apparatus of digital signal carrier wave frequency error - Google Patents

Measure the method and apparatus of digital signal carrier wave frequency error Download PDF

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Publication number
CN1725748A
CN1725748A CNA2005100853151A CN200510085315A CN1725748A CN 1725748 A CN1725748 A CN 1725748A CN A2005100853151 A CNA2005100853151 A CN A2005100853151A CN 200510085315 A CN200510085315 A CN 200510085315A CN 1725748 A CN1725748 A CN 1725748A
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output
nuclear
prs
result
delayer
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朴赞燮
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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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
    • H04L27/2657—Carrier synchronisation
    • 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
    • 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
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The carrier frequency error measuring equipment and the method for a kind of OFDM of being used for (OFDM) demodulated digital signal are disclosed.In thick carrier restorer, use PRS (phase reference code) to measure in the processing of carrier frequency error, needn't obtain all correlations about whole PRS.In other words, only 16 samplings are obtained correlations, and, obtain the size of whole correlations by the correlation that the principle combinations according to the nuclear of PRS should obtain.Therefore, reduce hardware size and power consumption significantly.

Description

Measure the method and apparatus of digital signal carrier wave frequency error
Technical field
The present invention relates to a kind of digit receiver system.More particularly, the present invention relates to a kind of carrier frequency error of measuring OFDM (OFDM) the digital broadcast data frame that the digit receiver system receives, recover equipment and the method handled to be used for thick carrier wave with the result that in the ofdm signal demodulation, uses this measurement.
Background technology
Available terrestrial radio broadcast system mainly comprises Europe, the U.S. and Nippon Standard at present, and all these has adopted the OFDM scheme.EUREKA-147, i.e. Ou Zhou digital audio broadcasting (DAB) scheme is used the strong COFDM (coded OFDM) of the multipath fading of anti-surface wave.At the DAB of the adopted DMB as DMB of Korea S, and the sound quality of tight dish (CD) grade, various service and the fabulous mobile quality of reception are provided based on Europe.
Figure 1A has shown the structure of COFDM digital data frames.With reference to Figure 1A, Frame has the null symbol (a) of following 76 OFDM code elements thereafter.Beginning in these 76 code elements be PRS (phase reference code) (b).Valid data code element (c), (d) follow in PRS (b) back.Null symbol (a) and PRS (b) have constituted the synchronizing channel of frame.
PRS (b) is data known between reflector and receiver, and provides phase reference for the differential modulation of next OFDM code element.In addition, PRS (b) also is used to detect the time synchronized of frame and code element.
Figure 1B shows an example by the PRS of FFT (fast fourier transform) demodulation, always has 1536 samplings (or sub-carrier signal).More particularly, the PRS of Figure 1B is in the transmission mode 1 of DAB system, and it is the signal by the frequency domain of FFT demodulation.
By convention, the thick carrier recovery system operation in the OFDM receiving system is to find and to compensate thick carrier frequency error.Thick carrier frequency error can be found by the degrees of offset of placing a pilot tone and measurement and reference position in frequency domain.Correlation generally is used to find pilot tone.PRS plays pilot tone in the DAB/DMB system.Problem is to increase inevitably for the size of the correlation hardware that obtains PRS.In first transmission mode of DAB, 1536 PRS are arranged, this just means the unacceptable macrostructure of acquisition correlation needs.Like this to the demand of big hardware for the low-power consumption of digital received system big obstacle.
Summary of the invention
Therefore, the object of the present invention is to provide a kind of Apparatus for () and method therefor, this equipment and method are measured the carrier for digital signal frequency error according to the demodulation of OFDM (OFDM) scheme, and by using PRS (phase reference code) to reduce the hardware size that is used to measure carrier frequency error.
By a kind of carrier for digital signal frequency error that is used to measure is provided, above-mentioned aspect of the present invention and/or other characteristics can be implemented basically, this digital signal by OFDM (OFDM) by demodulation and the PRS (phase reference code) of the combination that comprises at least one four nuclear arranged, this equipment comprises: correlator, obtain transmission PRS and and four nuclears of the predetermined local PRS that is complementary of the PRS of transmission between correlation; Delayer, with four nuclears of output delay of correlator, the twice of four nuclears, four nuclears three times, and the result's summation to postponing; And maximum value detector, in the output of adder, detect peaked position.
Correlator can comprise: first delayer, the PRS of reception frequency domain, and a nuclear of output delay, the twice of a nuclear and three times code element of a nuclear; 16 correlators obtain the correlation between half different set of nuclear of predetermined local PRS of half set and the PRS that is matched with transmission of nuclear of output of first delayer respectively; Second delayer postpones half of a kernel, the output of exporting 16 correlators of this delay with in the output of 16 correlators each; And first adder, to the output of 16 correlators and the output summation of second delayer.
First delayer can comprise: the 1-1 delayer, and with 32 samplings of PRS symbol delay of the frequency domain that receives, and the output result; The 1-2 delayer is with 32 samplings of output delay and the output result of 1-1 delayer; With the 1-3 delayer, with 32 samplings of output delay and the output result of 1-2 delayer.
16 correlators can comprise: first correlator, first of the PRS of the frequency domain that to receive and local PRS preset the correlation between half of nuclear; Second correlator obtains second of the output of 1-1 delayer and local PRS and presets correlation between half of nuclear; Third phase closes device, obtains the 3rd of the output of 1-2 delayer and local PRS and presets correlation between half of nuclear; With the 4th correlator, obtain the 4th of the output of 1-3 delayer and local PRS and preset correlation between half of nuclear.
Second delayer can comprise: the 2-1 delayer, with the half of the nuclear of output delay of first correlator and export the result; The 2-2 delayer is with the half of the nuclear of output delay of second correlator and export the result; The 2-3 delayer, third phase is closed device a nuclear of output delay half and export the result; With the 2-4 delayer, with the half of the nuclear of output delay of the 4th correlator and export the result.
Correlator can comprise: the 5th correlator, with the PRS of the frequency domain that receives and local PRS first presets nuclear that half multiplies each other and exports the result; The 3rd adder is to per four output summations of the 5th correlator; The phase difference compensation parts are about the phase difference between four nuclears of output compensation of the 3rd adder; With the 4th delayer,, obtain the correlation of each nuclear and the result that output obtains subsequently with the number that the output delay of phase difference compensation parts is examined.
The 3rd adder can comprise: the 3-1 adder, to the first, the 5th, the 9th and the 13 output summation of the 5th correlator; The 3-2 adder is to the second, the 6th, the tenth and the 14 output summation of the 5th correlator; The 3-3 adder is to the 3rd, the 7th, the 11 and the 15 output summation of the 5th correlator; With the 3-4 adder, to the 4th, the 8th, the 12 and the 16 output summation of the 5th correlator.
The phase difference compensation parts can comprise: the first phase difference compensation parts, about the output summation and the output result of 3-1 to 3-4 adder; The second phase difference compensation parts are about the phase differences of the output of 3-1 to 3-4 adder compensation first and second nuclears and export the result; Third phase potential difference compensating unit is about the phase difference of the output of 3-1 to 3-4 adder compensation the first and the 3rd nuclear and export the result; With the 4th phase difference compensation parts, about the phase difference of the output of 3-1 to 3-4 adder compensation the first and the 4th nuclear and export the result.
The 4th delayer can comprise: the 4-1 delayer, with the nuclear of output delay and the output result of the second phase difference compensation parts; The 4-2 delayer is with the twice of the nuclear of output delay of third phase potential difference compensating unit and export the result; With the 4-3 delayer, with three times of the nuclear of output delay of the 4th phase difference compensation parts and export the result.
According to an aspect of the present invention, provide a kind of method that is used to measure the digital signal carrier wave frequency error.This digital signal by OFDM (OFDM) by demodulation and have a PRS (phase reference code) of the combination that comprises at least one four nuclear.This method can comprise: obtain transmission PRS and and four nuclears of the predetermined local PRS that is complementary of the PRS of transmission between correlation; With four nuclears of output delay of correlator, the twice of four nuclears, four nuclears three times, and the result's summation to postponing; With the peaked position of detection in the output of adder.
The step that obtains correlation can comprise: (a) receive the PRS of frequency domain and output and have a nuclear having postponed a nuclear, twice, three times the code element of a nuclear; (b) obtain correlation between half different set of nuclear of half set of nuclear of output of step (a) and the predetermined local PRS that is complementary with the PRS of transmission respectively; (c) with half of the nuclear of each 16 correlator output delay of step (b), the output of exporting 16 correlators; (d) to the output of step (b) and the output summation of step (c).
Step (a) can comprise: (a-1) with 32 samplings of PRS symbol delay and the output result of the frequency domain that receives; (a-2) 32 of the output delaies of step (a-1) are sampled and the output result; (a-3) 32 of the output delaies of step (a-2) are sampled and the output result.
Step (b) can comprise: first of the PRS of the frequency domain that (b-1) to receive and local PRS presets the correlation between half of nuclear; (b-2) obtain half the correlation that second of the output of step (a-1) and local PRS presets nuclear; (b-3) obtain half the correlation that the 3rd of the output of step (a-2) and local PRS presets nuclear; (b-4) obtain half the correlation that the 4th of the output of step (a-3) and local PRS presets nuclear.
Step (c) can comprise: (c-1) with the half of the nuclear of output delay of step (b-1) and export the result; (c-2) with the half of the nuclear of output delay of step (b-2) and export the result; (c-3) with the half of the nuclear of output delay of step (b-3) and export the result; (c-4) with the half of the nuclear of output delay of step (b-4) and export the result.
The step that obtains correlation can comprise: (f) first half that presets nuclear of the PRS of the frequency domain that receives and local PRS multiplied each other and export the result; (g) per four outputs of step (f) are sued for peace; (h) about the phase difference between four nuclears of output compensation of step (g); (i) number that the output delay of step (h) is examined obtains the correlation of each nuclear and the result that output obtains subsequently.
Step (g) can comprise: (g-1) the first, the 5th, the 9th, the 13 output of step (f) is sued for peace; (g-2) the second, the 6th, the tenth, the 14 output of step (f) is sued for peace; (g-3) the 3rd, the 7th, the 11, the 15 output of step (f) is sued for peace; (g-4) the 4th, the 8th, the 12, the 16 output of step (f) is sued for peace.
Step (h) can comprise: (h-1) output of step (g-1) to (g-4) is sued for peace and the output result; (h-2) output with respect to step (g-1) to (g-4) compensates the phase difference of first and second nuclears and exports the result; (h-3) output with respect to step (g-1) to (g-4) compensates the phase difference of the first and the 3rd nuclear and exports the result; (h-4) output with respect to step (g-1) to (g-4) compensates the phase difference of the first and the 4th nuclear and exports the result.
Step (i) can comprise: (i-1) one of the output delay of step (h-2) is examined and the output result; (i-2) with the twice of the nuclear of output delay of step (h-2) and export the result; (i-3) with three times of the nuclear of output delay of step (h-2) and export the result.
Description of drawings
By the description of with reference to the accompanying drawings certain embodiments of the invention being carried out, above-mentioned aspect of the present invention and characteristics will become clearer, wherein:
Figure 1A represents the structure of COFDM (OFDM of coding) digital data frames;
Figure 1B represents the example by the PRS (phase reference code) in the frequency domain of FFT (fast fourier transform) demodulation;
Fig. 2 A represents to constitute 4 nuclears (kernel) of the PRS that uses according to the embodiment of the invention;
Fig. 2 B is illustrated in phase place rotation between two adjacent nuclears of Fig. 2 A;
Fig. 3 is the carrier frequency error measuring equipment block diagram according to the embodiment of the invention, and this equipment is measured carrier frequency error from the digital signal of OFDM demodulation;
Fig. 4 is a carrier frequency error measuring equipment block diagram according to another embodiment of the present invention, the carrier for digital signal frequency error of this device measuring OFDM demodulation;
Fig. 5 is the block diagram of the 5th correlator of the measuring equipment of Fig. 4; With
Fig. 6 is the flow chart that provides for the method for explaining measurement carrier frequency error in the OFDM receiving system according to the embodiment of the invention.
Embodiment
Now will be at length with reference to the preferred embodiments of the present invention, the example is represented in the accompanying drawings.
Explain characteristics of the present invention and aspect before, the structure of PRS (phase reference code) will be described briefly.
Fig. 2 A represents four nuclears according to the formation PRS of the embodiment of the invention.PRS can be configured as shown in Fig. 2 A and based on following mathematic(al) representation.
[equation 1]
Z l , k = e j φ k
Wherein, Z L, kRepresent that its each subcarrier is a plurality of subcarriers of the PRS of plural number.Value φ kDetermine each plural number, and be determined according to the mathematic(al) representation of following each nuclear about Fig. 2 A:
[equation 2]
φ k = π 2 ( h i , k - k ′ + n )
PRS is the combination at random of four unit nuclears of Fig. 2 A.Each nuclear has 32 plural numbers to form.More particularly, determined PRS when combining about predetermined value " n " when each nuclear with rotatable phase.
Each nuclear has two identical manifolds (e) and (f).Adjacent nuclear has the phase place rotation according to predetermined rule.
Fig. 2 B is illustrated in two phase place rotations between the adjacent nuclear.
With reference to Fig. 2 B, according to two nuclear phase position rotations of predetermined rule, and per four samplings repeat once.Such rule application changes phase difference in all four nuclears.The present invention proposes to improve the structure that obtains correlation based on the pre-defined rule in four nuclears that are present in PRS.
Fig. 3 is a block diagram of measuring the carrier frequency error measuring equipment of carrier frequency error from the digital signal of OFDM demodulation.
Measuring equipment 300 according to the embodiment of the invention can be realized in thick carrier resetting device (not shown).Thick carrier resetting device is by the sub-carrier frequencies of the unit that will be shifted with its local PRS that presets that the PRS that transmits be complementary, with the relevant correlation of PRS that obtains and transmit.Here, the PRS of transmission is in frequency domain and passes through FFT (fast fourier transform) by demodulation.Therefore, thick carrier resetting device obtains the poor of the position of maximum related value and itself and reference point.The integral multiple of the difference of maximal correlation position and reference point is confirmed as thick carrier frequency error.Thick then carrier resetting device recovers the carrier frequency error of measurement.
With reference to Fig. 3, comprise 16 correlators 330, first delayer 310, second delayer 350, the 3rd delayer 390, first adder 370, second adder 301 and maximum value detector 303 according to the measuring equipment 300 of the embodiment of the invention.
Can be configured so that 16 correlators 330 obtain 16 relevant correlations of sampling with the preceding sampling set (e) of each nuclear according to the measuring equipment 300 of the embodiment of the invention, because post-sampling collection (f) identical with preceding sampling set (e) (Fig. 2 A), so second delayer 350 postpones second sampling set (f), carries out then and computing.Repeat above-mentioned processing, first delayer 310 is sampled as unit delay with 32, and the result obtains the correlation about four nuclears.The correlation of 370 pairs of four nuclears of first adder summation, and repeat above-mentioned processing, the 3rd delayer 390 is sampled as unit delay with 128.Second adder 301 is carried out summation operation.Maximum value detector 303 detect about second adder 301 and peaked position, thereby the thick carrier frequency error of ensuing circuit (not shown) energy measurement.
First delayer 310 comprises 1-1 delayer 311,1-2 delayer 313 and 1-3 delayer 315, and each delayer outputs to 16 correlators 330 with the PRS of the delay of 32 samplings.
16 correlators 330 comprise first to the 4th correlator 331,333,335,337, and this each correlator obtains the correlation of 16 samplings respectively.The first all correlators 331, second correlator 333, third phase close device 335 and all are configured with identical structure except the input of the different correlation of each reception with the 4th correlator 337.
Local PRS is preset in 16 correlators 330 with the nuclear structure identical with the PRS of transmission.Here because nuclear back 16 samplings with preceding 16 identical, so only preceding 16 samplings of input nucleus.
Therefore, first correlator 331 is sequentially taken advantage of the PRS and local PRS first nuclear phase of transmission, and by summation obtains correlation to the result.First correlator 331 is exported this correlation then.
Second nuclear of the local PRS that 333 acquisitions of second correlator are preset is about the correlation of the PRS of the transmission of 32 sampling delay.
Third phase closes device 335 and the 4th correlator 337 also obtains correlation as first correlator 331 and second correlator 333.
Second delayer 350 will postpone the unit of 16 samplings respectively from four outputs of 16 correlators 330, and output to first adder 370.Second delayer comprises that 2-1 is to 2-4 delayer 351,353,355,357.Therefore, obtain correlation, sampling set (e) (Fig. 2 A) before this sampling set (f) repeats about the post-sampling collection (f) of each nuclear.
First adder 370 comprises 1-1 adder 371,1-2 adder 373,1-3 adder 375,1-4 adder 377 and 1-5 adder 379.The output summation of 370 pairs 16 correlators 330 of first adder and second delayer 350, and 379 couples of 1-1 of 1-5 adder are to the output summation of 1-4 adder 371,373,375 and 377.
1-5 adder 379 and be imported into the 3rd delayer 390.
The 3rd delayer 390 comprises that 3-1 is to 3-3 delayer 391,393,395.The output of the delays of 128 samplings by output 1-5 adder 379, the correlation that 1-5 adder 379 obtains about all nuclears of PRS.Because PRS has four nuclears that 128 sampling repeated combinations are arranged, so the processing that correlation can not need other being used to obtain correlation by postponing simply obtains.
3-1 delayer 391 is with 4 nuclears of output delay (128 samplings just) of 1-5 adder 379.
3-2 delayer 393 is with 4 nuclears of output delay (128 samplings just) of 3-1 delayer 391.
3-3 delayer 395 is with 4 nuclears of output delay (128 samplings just) of 3-2 delayer 393.
Second adder 301 try to achieve the output of first adder 370 and the 3rd delayer 390 output and, obtain final correlation, and the value that will obtain outputs to maximum value detector 303.
Maximum value detector obtains the position of the PRS maximum related value of local PRS and transmission from the output of second adder 301.Position based on the maximum related value that is obtained by maximum value detector 303 has the thick carrier resetting device (not shown) compensating carrier frequency error according to the measuring equipment 300 of the embodiment of the invention.
Fig. 4 is the block diagram of carrier frequency error measuring equipment according to another embodiment of the present invention, and this equipment is measured carrier frequency error from the digital signal of OFDM demodulation.
With reference to Fig. 4, measuring equipment 400 has the structure similar to the measuring equipment 300 of Fig. 3.Unique difference is that the equipment 400 of Fig. 4 does not have first delayer 310 and 16 correlators 330, still comprises the 5th correlator 401, the 3rd adder 410, differs compensating unit 430 and the 4th delayer 450.Therefore, the same parts of Fig. 4 is with reference to the identical label of Fig. 3, and its detailed being described as will be omitted for purpose of brevity.
The measuring equipment 400 of Fig. 4 can omit second correlator 333, third phase and close device 335 and the 4th correlator 337, and this is because it has utilized regularity in four nuclears (Fig. 2 A and Fig. 2 B) of PRS.Therefore, the size of hardware can be reduced widely.
The measuring equipment 400 of Fig. 4 is taken advantage of with the nuclear phase of a selection of 4 nuclears of the local PRS that produces in receiver at the PRS of the 5th correlator 401 with transmission.Per four results summation that 410 pairs of the 3rd adders multiply each other.Because phase difference compensation parts 430 multiply each other with the output of the 3rd adder 410 and from the phase difference that calculates the nuclear of selecting the nuclear of (calculation-intended) intentionally, so the correlation of each nuclear can be obtained.Afterwards, because the 4th delayer 450 postpones repetition periods, so obtain the output identical with 16 correlators 330 of Fig. 3.
The 5th correlator 401 is taken advantage of the nuclear phase of a selection of the PRS of transmission and 4 nuclears of local PRS.
Fig. 5 is the 5th a correlator block diagram of the measuring equipment of Fig. 4.With reference to Fig. 5, the 5th correlator 401 comprises 16 delayer 401a to 401p and 16 multiplier 403a to 403p.
Each delayer 401a to 401p postpones a sample unit with the PRS of transmission, and the output result.
16 samplings of the nuclear of the output of multiplier 403a to 403p self-dalay device in future 401a to 401p and the selection of local PRS are multiplied each other, and the result is outputed to the 3rd adder 410.
The 5th correlator 401 can not use multiplier 403a to 403p, but is replaced by the combination of being used general adder (not shown) and subtracter (not shown) by the mode of addition well known in the art and subtraction to use.
As shown in Figure 5, the 3rd adder 410 is respectively to the output summation of per four multipliers of 403a to 403p.The 3rd adder 410 comprises 3-1 to 3-4 adder 411,413,415,417.The output of the 3rd adder 410 is sent to phase difference compensation parts 430.
The output of the output of the first multiplier 403a of 411 pairs the 5th correlators 401 of 3-1 adder, the output of the 5th multiplier 403e, the 9th multiplier 403i and the output of the 13 multiplier 403m summation, and the output of 413 couples second multiplier 403b of 3-2 adder, the output of the 6th multiplier 403f, the output of the tenth multiplier 403j and the output summation of the 14 multiplier 403n.Be equally applicable to 3-3 adder 415 and 3-4 adder 417.
Phase difference compensation parts 430 comprise first to fourth phase difference compensation parts 431,433,435,437.The phase difference and the output multiplication of the 3rd adder 410 that phase difference compensation parts 430 are provided with the difference of each nuclear (Fig. 2 B), and to the multiplied result summation, thereby the correlation of acquisition 16 samplings identical with the correlation of 16 correlators 330.
The compensation of the first phase difference compensation parts 431 is to four first phase differences that output is predetermined of 3-1 to 3-4 adder 411,413,415,417, to four results' summations and output addition and.
In the same way, second to the 4th phase difference compensation parts, 433,435,437 compensation, second to the 4th phase difference.Phase difference is corresponding value, and this value is used to compensate the poor of phase place rotation between the nuclear of the local PRS that is input to the 5th correlator 401 and its excess-three nuclear.Because first phase difference is " 0 ", so the first phase difference compensation parts 431 are directly sued for peace and the output result to 4 outputs of 3-1 to 3-4 adder 411,413,415,417.
The output of the 4th delayer 450 phase retardation difference compensating units 430.
4-1 delayer 451 is with 32 samplings of output delay of the second phase difference compensation parts 433.
4-2 delayer 453 is with 64 samplings of output delay of third phase potential difference compensating unit 435.
4-3 delayer 455 is with 96 samplings of output delay of the 4th phase difference compensation parts 437.
The output of the 4th delayer 450 is identical with the output of 16 correlators 330 of Fig. 3.The output of the 4th delayer 450 is imported into second delayer 350.
According to a further aspect in the invention, the 4th delayer 450 can be set at phase difference compensation parts front to carry out delay in advance.
According to a further aspect in the invention, part correlation can additionally be used to minimize by may influencing that the symbol timing error produces.
Fig. 6 is the carrier frequency error method of measurement flow chart that is provided to explain OFDM (OFDM) receiving system according to the embodiment of the invention.The flow chart of Fig. 6 is based on the measuring equipment 400 of Fig. 4.
One of 4 nuclears of the local PRS that the PRS of transmission and the inside of receiver produce are at the 5th correlator 401 multiply each other (S601).
Per four results that multiply each other in the 5th correlator 401 are sequentially obtained, summation in 3-1 to 3-4 adder 411,413,415,417, and this result is output to phase difference compensation parts 430.
Phase difference compensation parts 430 will be at the nuclears of the selection that just is imported into the 5th correlator 401 and are had a mind to participate in the predetermined phase difference between the nuclear of computing and the output multiplication of 3-1 to 3-4 adder 411,413,415,417, and multiplied result is sued for peace.
By in the 4th delayer 450, accumulating and postponing a repetition period, obtain the correlation of 16 samplings (e) (or sub-carrier signal) of each nuclear.The output of the first phase difference compensation parts 431 is directly transmitted, the output of the second phase difference compensation parts 433 has been delayed 32 samplings, the output of third phase potential difference compensating unit 435 has been delayed 64 samplings, and the output of the 4th phase difference compensation parts 437 has been delayed 96 samplings (S603).
For the correlation of second sampling set (f) that obtains each nuclear, the output of the 4th delayer 450 is delayed 16 samplings at second delayer 350.This result is summed in the 1-1 to 1-4 of first adder 370 adder 371,373,375,377 then.
The output of 1-1 to 1-4 adder 371,373,375,377 is sued for peace in 1-5 adder 379.The correlation identical (S605) of result and 128 samplings.
The 3rd delayer 390 postpones the output and nuclear corresponding 128 samplings of repetition period of 1-5 adder 379 cumulatively.
When the output summation of the output of 301 pairs of 1-5 adders 379 of second adder and the 3rd delayer 390, obtain final correlation (S607).
From final correlation, maximum value detector 303 detects the position of maximum related value, thereby can measure carrier frequency error (S609).
The example of the carrier frequency error method of measurement of OFDM receiving system is with reference to of the present invention several
Embodiment is described.
As above explain, using PRS to measure in the carrier frequency error, with a final correlation of equipment acquisition that obtains the correlation of 16 samplings with reference to several embodiments of the present invention.As a result, reduced to comprise for example size of the hardware of multiplier component significantly, and computation requirement and power consumption are reduced greatly also.
Aforesaid embodiment and advantage are exemplary, are not interpreted as limiting the present invention.This religion is stated and can easily be applied to other types equipment.In addition, the description meant for illustration of the embodiment of the invention does not limit the scope of the claims, and a lot of replacements, modification and change are obvious to those skilled in the art.

Claims (18)

1, a kind of equipment that is used to measure the carrier for digital signal frequency error, by demodulation and the PRS (phase reference code) of the combination that comprises at least one four nuclear is arranged, this equipment comprises this digital signal by OFDM (OFDM):
Correlator, obtain transmission PRS and and four nuclears of the predetermined local PRS that is complementary of the PRS of transmission between correlation;
Delayer, with four nuclears of output delay of correlator, the twice of four nuclears, four nuclears three times, and the result's summation to postponing; With
Maximum value detector detects peaked position in the output of adder.
2, equipment as claimed in claim 1, wherein, correlator comprises:
First delayer, the PRS of reception frequency domain, and a nuclear of output delay, the twice of a nuclear and three times code element of a nuclear;
16 correlators obtain the correlation between half different set of nuclear of predetermined local PRS of half set and the PRS that is matched with transmission of nuclear of output of first delayer respectively; With
Second delayer postpones half of a kernel, the output of exporting 16 correlators of this delay with in the output of 16 correlators each;
First adder is to the output of 16 correlators and the output summation of second delayer.
3, equipment as claimed in claim 2, wherein, first delayer comprises:
The 1-1 delayer, with 32 samplings of PRS symbol delay of the frequency domain that receives, and the output result;
The 1-2 delayer is with 32 samplings of output delay and the output result of 1-1 delayer; With
The 1-3 delayer is with 32 samplings of output delay and the output result of 1-2 delayer.
4, equipment as claimed in claim 3, wherein, 16 correlators comprise:
First correlator, first of the PRS of the frequency domain that to receive and local PRS preset the correlation between half of nuclear;
Second correlator obtains second of the output of 1-1 delayer and local PRS and presets correlation between half of nuclear;
Third phase closes device, obtains the 3rd of the output of 1-2 delayer and local PRS and presets correlation between half of nuclear; With
The 4th correlator obtains the 4th of the output of 1-3 delayer and local PRS and presets correlation between half of nuclear.
5, equipment as claimed in claim 4, wherein, second delayer comprises:
The 2-1 delayer is with the half of the nuclear of output delay of first correlator and export the result;
The 2-2 delayer is with the half of the nuclear of output delay of second correlator and export the result;
The 2-3 delayer, third phase is closed device a nuclear of output delay half and export the result; With
The 2-4 delayer is with the half of the nuclear of output delay of the 4th correlator and export the result.
6, equipment as claimed in claim 1, wherein, correlator comprises:
The 5th correlator is with the PRS of the frequency domain that receives and local PRS first presets nuclear that half multiplies each other and exports the result;
The 3rd adder is to per four output summations of the 5th correlator;
The phase difference compensation parts are about the phase difference between four nuclears of output compensation of the 3rd adder; With
The 4th delayer with the number that the output delay of phase difference compensation parts is examined, obtains the correlation of each nuclear and the result that output obtains subsequently.
7, equipment as claimed in claim 6, wherein, the 3rd adder comprises:
The 3-1 adder is to the first, the 5th, the 9th and the 13 output summation of the 5th correlator;
The 3-2 adder is to the second, the 6th, the tenth and the 14 output summation of the 5th correlator;
The 3-3 adder is to the 3rd, the 7th, the 11 and the 15 output summation of the 5th correlator; With
The 3-4 adder is to the 4th, the 8th, the 12 and the 16 output summation of the 5th correlator.
8, equipment as claimed in claim 7, wherein, the phase difference compensation parts comprise:
The first phase difference compensation parts are about the output summation and the output result of 3-1 to 3-4 adder;
The second phase difference compensation parts are about the phase differences of the output of 3-1 to 3-4 adder compensation first and second nuclears and export the result;
Third phase potential difference compensating unit is about the phase difference of the output of 3-1 to 3-4 adder compensation the first and the 3rd nuclear and export the result; With
The 4th phase difference compensation parts are about the phase difference of the output of 3-1 to 3-4 adder compensation the first and the 4th nuclear and export the result.
9, equipment as claimed in claim 8, wherein, the 4th delayer comprises:
The 4-1 delayer is with the nuclear of output delay and the output result of the second phase difference compensation parts;
The 4-2 delayer is with the twice of the nuclear of output delay of third phase potential difference compensating unit and export the result; With
The 4-3 delayer is with three times of the nuclear of output delay of the 4th phase difference compensation parts and export the result.
10, a kind of method that is used to measure the carrier for digital signal frequency error, by demodulation and have the PRS (phase reference code) of the combination that comprises at least one four nuclear, the method comprising the steps of by OFDM (OFDM) for this digital signal:
Obtain transmission PRS and and four nuclears of the predetermined local PRS that is complementary of the PRS of transmission between correlation;
With four nuclears of output delay of correlator, the twice of four nuclears, four nuclears three times, and the result's summation to postponing; With
In the output of adder, detect peaked position.
11, method as claimed in claim 10, wherein, the step that obtains correlation comprises:
(a) receive the PRS of frequency domain and output and have three times the code element that has postponed a nuclear, the twice of a nuclear, a nuclear;
(b) obtain correlation between half different set of nuclear of half set of nuclear of output of step (a) and the predetermined local PRS that is complementary with the PRS of transmission respectively;
(c) with half of the nuclear of output delay of each 16 correlator of step (b), the output of exporting 16 correlators; With
(d) to the output of step (b) and the output summation of step (c).
12, method as claimed in claim 11, wherein, step (a) comprising:
(a-1) with 32 samplings of PRS symbol delay and the output result of the frequency domain that receives;
(a-2) 32 of the output delaies of step (a-1) are sampled and the output result; With
(a-3) 32 of the output delaies of step (a-2) are sampled and the output result.
13, method as claimed in claim 12, wherein, step (b) comprising:
(b-1) first of the PRS of the frequency domain that to receive and the local PRS correlation that presets between half of nuclear;
(b-2) obtain half the correlation that second of the output of step (a-1) and local PRS presets nuclear;
(b-3) obtain half the correlation that the 3rd of the output of step (a-2) and local PRS presets nuclear; With
(b-4) obtain half the correlation that the 4th of the output of step (a-3) and local PRS presets nuclear.
14, method as claimed in claim 13, wherein, step (c) comprising:
(c-1) with the half of the nuclear of output delay of step (b-1) and export the result;
(c-2) with the half of the nuclear of output delay of step (b-2) and export the result;
(c-3) with the half of the nuclear of output delay of step (b-3) and export the result; With
(c-4) with the half of the nuclear of output delay of step (b-4) and export the result.
15, method as claimed in claim 10, wherein, the step that obtains correlation comprises:
(f) first half that presets nuclear of the PRS of the frequency domain that receives and local PRS multiplied each other and export the result;
(g) per four outputs of step (f) are sued for peace;
(h) about the phase difference between four nuclears of output compensation of step (g); With
(i) number that the output delay of step (h) is examined obtains the correlation of each nuclear and the result that output obtains subsequently.
16, method as claimed in claim 15, wherein, step (g) comprising:
(g-1) the first, the 5th, the 9th, the 13 output of step (f) is sued for peace;
(g-2) the second, the 6th, the tenth, the 14 output of step (f) is sued for peace;
(g-3) the 3rd, the 7th, the 11, the 15 output of step (f) is sued for peace; With
(g-4) the 4th, the 8th, the 12, the 16 output of step (f) is sued for peace.
17, method as claimed in claim 16, wherein, step (h) comprising:
(h-1) output of step (g-1) to (g-4) is sued for peace and the output result;
(h-2) output with respect to step (g-1) to (g-4) compensates the phase difference of first and second nuclears and exports the result;
(h-3) output with respect to step (g-1) to (g-4) compensates the phase difference of the first and the 3rd nuclear and exports the result; With
(h-4) output with respect to step (g-1) to (g-4) compensates the phase difference of the first and the 4th nuclear and exports the result.
18, method as claimed in claim 17, wherein, step (i) comprising:
(i-1) one of the output delay of step (h-2) is examined and the output result;
(i-2) with the twice of the nuclear of output delay of step (h-2) and export the result; With
(i-3) with three times of the nuclear of output delay of step (h-2) and export the result.
CNA2005100853151A 2004-07-22 2005-07-22 Measure the method and apparatus of digital signal carrier wave frequency error Pending CN1725748A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101145834B (en) * 2006-09-12 2010-12-15 美国博通公司 Method and system for estimating signal error in a communication system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101145834B (en) * 2006-09-12 2010-12-15 美国博通公司 Method and system for estimating signal error in a communication system

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BRPI0503020A (en) 2006-03-07

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