CN101237436B - A method and circuit for detecting carrier frequency deviation and sampling frequency deviation - Google Patents
A method and circuit for detecting carrier frequency deviation and sampling frequency deviation Download PDFInfo
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Abstract
The invention provides a method for detecting the carrier frequency shift and the sampling frequency shift in an OFDM system and a circuit thereof. The method for detecting the carrier frequency shift and the sampling frequency shift in the OFDM system comprises the following steps that: related calculations are done on two adjacent code elements on each sub-carrier with a steering signal in order to obtain the related information of each steering signal; the channel frequency response energy of each carrier and each channel serial number are adopted to obtain the information of each channel; the related information of each steering signal, the channel frequency response energy of each sub-carrier and each channel serial number are adopted to obtain the related information of each steering channel; the related information of each steering channel and the information of each channel are adopted to obtain the related detection information of the frequency shift and the sampling shift. The invention combines all the information and the arithmetic elements necessary to the application, thereby decreasing the complexity of the circuit. The method of splitting operation can be also adopted to decrease the difficulty of the multiply operation and the division operation and to keep the accuracy of information.
Description
Technical field
The present invention is about OFDM modulation (OFDM, Orthogonal Frequency DivisionMultiplex) system, especially about the method and the circuit of detected carrier frequency shift (FS) and sampling frequency deviation in the ofdm system.
Background technology
At present, in digit broadcasting system, be extensive use of the OFDM modulation tech.The topmost advantage of OFDM modulation tech is that the ability of anti-multipath decline is strong, yet but very responsive for carrier frequency shift or sampling frequency deviation.Especially when fundamental frequency signal adopts high exponent number quadrature amplitude modulation (QAM, QuadratureAmplitude Modulation) modulation, be example with 64QAM, its tolerable carrier frequency offset is about one thousandth.So detected carrier frequency shift (FS) or sampling frequency deviation are problem important in the ofdm system.
At the general Digital Television (DVB-T that adopts the OFDM modulation tech, Digital VideoBroadcasting-Terrestrial) or digital audio broadcasting (DAB, Digital AudioBroadcasting) the detected carrier frequency shift (FS) of being adopted in the receiver or the method for sampling frequency deviation are carried out fast fourier transform (FFT with received signal R earlier, Fast Fourier Transform) obtain frequency domain information z (l, k).Wherein k represents the sequence number of subcarrier, and 1 represents the sequential sequence number of OFDM symbol.Correct at the FFT window, intercarrier is disturbed under (ICI, Inter Channel Interference) very little situation mutually, can be expressed as:
C (l, k), H (l, k), f, ζ,
N (l, k) white Gaussian noise that causes of the code element, channel frequency response, carrier frequency shift, sampling frequency deviation, carrier wave initial phase deviation, phase noise and the receiving terminal that send of expression respectively.Continuously guided signal (CP, Continual Pilot) transmission value of same position in each OFDM code element is the same, and the steering signal on adjacent two code element same positions is made related operation, can obtain:
The detection technique of existing carrier frequency shift and sampling frequency deviation is as described below.Earlier with z
d(l is k) according to the subcarrier separated into two parts.The CP of first
-Be the subcarrier that is distributed in the centered carrier left side, k ∈ [(K-1)/2,0).Second portion CP
+Be the subcarrier that is distributed in centered carrier the right, k ∈ [0 ,+(K-1)/2).First is added up with the bit position mutually of second portion, obtains:
Pass through θ
+(l) and θ
-(l) cooperate proper circuit to carry out the detected value that computing can obtain carrier frequency shift and sampling frequency deviation.
This existing detection method realizes easily that actually but smaller in signal noise, perhaps error is bigger under the frequency selective fading serious situation, and convergence rate is slower.In view of this, the present invention proposes a kind of least mean-square error technology of utilizing in signal noise under the smaller and frequency selective fading serious situation, the accurate method of detected carrier frequency shift (FS) and sampling frequency deviation still is to meet the stronger demand of ofdm system.
Summary of the invention
The invention provides a kind of method that detects carrier frequency shift and sampling frequency deviation in the ofdm system, at first received signal R being carried out FFT handles, obtain frequency-domain information, interior adjacent two code elements of frequency-domain information that will have each subcarrier of steering signal are again carried out related operation, obtain each steering signal relevant information; To have the channel frequency response energy addition of each subcarrier of steering signal again, obtain first channel information; The channel frequency response energy that then will have each subcarrier of steering signal is multiplied by addition again after separately the channel designator respectively, obtains second channel information; After the channel frequency response energy that will have each subcarrier of steering signal again was multiplied by separately channel designator square respectively, addition again obtained the 3rd channel information; Then the phase information of each steering signal relevant information is multiplied by the channel frequency response energy addition again of each subcarrier respectively, obtains the first pilot channel relevant information with steering signal; Phase information with each steering signal relevant information is multiplied by the channel frequency response energy of each subcarrier with steering signal and the channel designator addition again that is multiplied by respectively separately respectively again, obtains the second pilot channel relevant information; After then the 3rd channel information being multiplied by the first pilot channel relevant information earlier, the product that deducts the second channel information and the second pilot channel relevant information again is to obtain one first difference, the product of first channel information and the 3rd channel information deduct second channel information square obtaining one second difference, described first difference divided by described second difference to obtain the detection relevant information of frequency shift (FS); After at last first channel information being multiplied by the second pilot channel relevant information earlier, the product that deducts the second channel information and the first pilot channel relevant information again is to obtain one the 3rd difference, the product of first channel information and the 3rd channel information deduct second channel information square obtaining one the 4th difference, described the 3rd difference divided by described the 4th difference to obtain the detection relevant information of sample offset; Above-mentioned computing can be adopted the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.
The present invention also provides a kind of circuit that detects carrier frequency shift and sampling frequency deviation in the ofdm system, carries out said method with first to the 7th circuit respectively; Wherein also can adopt the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.
The present invention also provides a kind of circuit that detects carrier frequency shift and sampling frequency deviation in the ofdm system, merges to use needed information and arithmetic element, calculates each pilot channel relevant information and the complexity of each channel information with the reduction circuit with two circuit; Wherein also can adopt the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.
In sum, the method of a kind of detected carrier frequency shift (FS) provided by the invention and sampling frequency deviation and circuit have to merge uses needed information and arithmetic element, reduce the complexity of circuit, also can adopt the method that splits computing with difficulty that lowers the multiplication and division computing and the advantage of possessing the accuracy of information.
Description of drawings
Fig. 1 is the method flow diagram according to carrier frequency shift and sampling frequency deviation in the detection ofdm system of one embodiment of the invention;
Fig. 2 is the circuit block diagram of carrier frequency shift and sampling frequency deviation in the demonstration detection ofdm system according to another embodiment of the present invention;
Fig. 3 is the circuit block diagram of carrier frequency shift and sampling frequency deviation in the demonstration detection ofdm system according to another embodiment of the present invention.
The main element symbol description:
11～carry out FFT and related operation obtains each steering signal relevant information, 12～carry out computing according to the channel frequency response of each subcarrier with channel designator separately to obtain each channel information, 13～carry out computing according to each steering signal relevant information and its channel frequency response to obtain each pilot channel relevant information, 14～carry out computing according to each channel information and each pilot channel relevant information, 15～obtain the detection relevant information of frequency shift (FS) and sample offset, 21～the first computing circuits, 22～the second computing circuits, 23～the 3rd computing circuits, 24～the 4th computing circuits, 25～the 5th computing circuits, 26～the 6th computing circuits, 27～the 7th computing circuits, 31～the first computing circuits, 32～the second computing circuits, 33～the 3rd computing circuits, 311～FFT arithmetic element, 312～related operation unit, 313～channel energy arithmetic element, 321,322,331,333,335～accumulator, 323,324,332,334～multiplier.
Embodiment
According to one embodiment of the invention, at first, the received signal R of receiving terminal in the ofdm system is carried out FFT handle, obtaining the information of received signal R on frequency domain, as follows:
C (l, k), H (l, k), f, ζ,
N (l, k) white Gaussian noise that causes of the code element, channel frequency response, carrier frequency shift, sampling frequency deviation, carrier wave initial phase deviation, phase noise and the receiving terminal that send of expression respectively.Interior adjacent two code elements of frequency-domain information that will have each subcarrier of steering signal are again carried out related operation, obtain each steering signal relevant information, as shown in the formula:
In order to simplify computing, the phase bit position of only getting each steering signal relevant information carries out subsequent detection, obtains:
Smaller in order to improve prior art in signal noise, the perhaps bigger shortcoming of error under the frequency selective fading serious situation, one embodiment of the invention consider that more the influence of noise and frequency selective fading is to detect.The suffered noise effect of each subcarrier is different with the influence of frequency selective fading, causes the confidence level difference of each subcarrier, so utilize each sub-carrier frequencies response energy | H (l, k) |
2The confidence level that reflects each subcarrier is to promote the accuracy that detects.Be expressed as and the component of noise can be similar to:
var(n′(l，k))≈σ
2/|H(l，k)|
2
With each sub-carrier frequencies response energy | H (l, k) |
2As weight, thereby obtain utilizing the expression formula of detection frequency shift (FS) of square error method and sample offset as follows:
Make the square-error minimum, make frequency shift (FS) and sample offset detected value the most accurate, following formula can be carried out partial differential to frequency shift (FS) f and sample offset ζ respectively, obtain:
Solve an equation and obtain:
According to above theoretical foundation, we can obtain a kind of method that detects carrier frequency shift and sampling frequency deviation in the ofdm system, and Fig. 1 is the method flow diagram according to one embodiment of the invention.Step 11 is carried out the FFT processing with received signal, obtains frequency-domain information, and interior adjacent two code elements of frequency-domain information that will have each subcarrier of steering signal are again carried out related operation, obtain each steering signal relevant information.
Then carry out step 12, carry out computing according to the channel frequency response of each subcarrier with channel designator separately and obtain each channel information.Wherein
Be about to have the channel frequency response energy addition of each subcarrier of steering signal, resulting first channel information.
The channel frequency response energy that will have each subcarrier of steering signal is multiplied by addition again after separately the channel designator, resulting second channel information respectively.And the 3rd channel information
The channel frequency response energy that will have each subcarrier of steering signal is multiplied by addition again after separately the channel designator square respectively.
Carrying out step 13 again carries out computing according to each steering signal relevant information and its channel frequency response and obtains each pilot channel relevant information.The first pilot channel relevant information wherein
Each steering signal relevant information is multiplied by the channel frequency response energy addition again of each subcarrier respectively with steering signal.
Each steering signal relevant information is multiplied by the channel frequency response energy of each subcarrier with steering signal and the channel designator addition again that is multiplied by respectively separately respectively.It should be noted that in the aforesaid equation
Represent phase noise, can ignore its influence at this.
Obtain carrying out step 14 again after the information of t1, t2, t3, s1, s2 each channel information and each pilot channel relevant information are carried out computing, can enter step 15, obtain the detection relevant information of frequency shift (FS) f and sample offset ζ.Detailed method deducts second channel information t2 again and is multiplied by the second pilot channel relevant information s2 for the 3rd channel information t3 is multiplied by the first pilot channel relevant information s1, again divided by the first channel information t1 be multiplied by deduct behind the 3rd channel information t3 second channel information t2 square, can obtain the detection relevant information of frequency shift (FS) f; Deduct second channel information t2 again and be multiplied by the first pilot channel relevant information s1 and the first channel information t1 is multiplied by the second pilot channel relevant information s2, again divided by the first channel information t1 be multiplied by deduct behind the 3rd channel information t3 second channel information t2 square, obtain the detection relevant information of sample offset ζ.
In order to ensure the accuracy of above-mentioned each information, its bit width may be bigger.So have certain degree of difficulty in above-mentioned every multiplication and division computing actual carrying out.Can adopt the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.For example t1 has 20, and t3 has 30.Can be expressed as respectively:
t1＝a
1·2
10+a
0
t3＝c
2·2
20+c
1·2
10+c
0
A wherein
iAnd C
i(i ∈ 0,1,2) all are 10 integers.Adopt the fractionation computing to carry out multiplying each other of t1 and t3, can be expressed as follows:
t
1·t
3＝(a
1·c
2)·2
30+(a
1·c
1+a
0·c
2)·2
20+(a
1·c
0+a
0·c
1)+a
0·c
0
The multiplier that only need use 10 in calculating process carries out a thus
iAnd C
iThe phase multiplication, greatly reduce the cost of arithmetic element.Certainly, above-mentioned each information also similarly method adopt and split computing and carry out multiplication or division to reduce the cost of arithmetic element.
Fig. 2 is the circuit block diagram of carrier frequency shift and sampling frequency deviation in the demonstration detection ofdm system according to another embodiment of the present invention.In order to realize the detection method of sample offset and frequency shift (FS), can utilize several circuit in conjunction with running.Wherein comprise first computing circuit 21, received signal R has been carried out FFT handle in the frequency-domain information of each subcarrier that has steering signal in the frequency-domain information of back gained adjacent two code elements and carry out related operation, obtained each steering signal relevant information.
Second computing circuit 22 is coupled to first computing circuit 21 to receive each steering signal relevant information, will have the channel frequency response energy addition of each subcarrier of steering signal, obtains the first channel information t1.The 3rd computing circuit 23 is coupled to first computing circuit 21 to receive each steering signal relevant information, and the channel frequency response energy that will have each subcarrier of steering signal is multiplied by addition again after separately the channel designator respectively, obtains second channel information t2.The 4th computing circuit 24 is coupled to first computing circuit 21 to receive each steering signal relevant information, and the channel frequency response energy that will have each subcarrier of steering signal is multiplied by addition again after separately the channel designator square respectively, obtains the 3rd channel information t3.
The 5th computing circuit 25, be coupled to first computing circuit 21 to receive each steering signal relevant information, each steering signal relevant information is multiplied by the channel frequency response energy addition again of each subcarrier with steering signal respectively, obtains the first pilot channel relevant information s1.The 6th computing circuit 26, be coupled to first computing circuit 21 to receive each steering signal relevant information, each steering signal relevant information is multiplied by the channel frequency response energy of each subcarrier with steering signal and the channel designator k addition again that is multiplied by respectively separately respectively, obtains the second pilot channel relevant information s2.
The 7th computing circuit 27 is coupled to second to the 6th computing circuit to receive each channel information and each pilot channel relevant information.The 3rd channel information is multiplied by the first pilot channel relevant information to be deducted second channel information again and is multiplied by the second pilot channel relevant information, again divided by first channel information be multiplied by deduct behind the 3rd channel information second channel information square, resulting frequency offset information is delivered to frequency synchronisation circuit to reduce receiving terminal and the nonsynchronous error of transmitting terminal frequency; First channel information is multiplied by the second pilot channel relevant information to be deducted second channel information again and is multiplied by the first pilot channel relevant information, again divided by first channel information be multiplied by deduct behind the 3rd channel information second channel information square, resulting sample offset information is delivered to the sample-synchronous circuit to reduce receiving terminal and transmitting terminal nonsynchronous error of sampling.
The internal structure of the 7th computing circuit 27 also can be divided into four parts, and first is t1t3_t2t2_com, with first channel information be multiplied by deduct behind the 3rd channel information second channel information square.Second portion is t2s2_t3s1_car, second channel information is multiplied by the second pilot channel relevant information deducts the 3rd channel information again and be multiplied by the first pilot channel relevant information.Third part is t2s1_t1s2_sam, second channel information is multiplied by the first pilot channel relevant information deducts first channel information again and be multiplied by the second pilot channel relevant information.The 4th part is a division circuit, and the result of second portion delivers to frequency synchronisation circuit to reduce receiving terminal and the nonsynchronous error of transmitting terminal frequency divided by the result of first with resulting frequency offset information; The result of third part is divided by the result of first, and resulting sample offset information is delivered to the sample-synchronous circuit to reduce receiving terminal and transmitting terminal nonsynchronous error of sampling, and division circuit can be multiplexing.
In this embodiment, also can run into the problem of information accuracy and computational complexity, also can adopt the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.
Fig. 3 is for showing circuit block diagram according to another embodiment of the present invention.Because each pilot channel relevant information and the needed information of each channel information and employed arithmetic element are very similar, also can merge needed information of application and arithmetic element to reduce the complexity of circuit.Circuit after the improvement has comprised first computing circuit 31, has a FFT arithmetic element 311, a related operation unit 312 and a channel energy arithmetic element 313.FFT arithmetic element 311 is carried out FFT with received signal R and is handled.Handle in the frequency-domain information of each subcarrier that related operation unit 312, back and channel energy arithmetic element 313 have steering signal respectively in the frequency-domain information with gained adjacent two code elements and carry out related operation and Energy Estimation, export each steering signal relevant information θ (l respectively, k) with each sub-carrier frequencies response energy | H (l, k) |
2
The 3rd computing circuit 33, be coupled to first computing circuit 31 with receive each steering signal relevant information θ (l, k) with each sub-carrier frequencies response energy | H (l, k) |
2The 3rd computing circuit 33 has the channel frequency response energy addition that an accumulator 331 will have each subcarrier of steering signal, obtains the first channel information t1.The channel frequency response energy that utilizes a multiplier 332 will have each subcarrier of steering signal again utilizes an accumulator 333 additions after being multiplied by separately channel designator k respectively again, obtains second channel information t2.The channel frequency response energy that utilizes a multiplier 334 will have each subcarrier of steering signal again is multiplied by channel designator square k separately respectively
2After, utilize an accumulator 335 additions again, obtain the 3rd channel information t3.In specific implementation, because to each sub-carrier frequencies response energy | H (l, k) |
2Required precision is not high, and the continuous pilot signal real part absolute value that sends all is 4/3, and imaginary part all is 0, can use received signal z (l, real part absolute value k) | Re (z (l, k)) | replace | H (l, k) |
2, and can with | Re (z (l, k)) | be quantized into and make things convenient for 2 of computing
n, 2
N-1＜| Re (z (l, k)) |≤2
nThereby, in the circuit with | H (l, k) |
2The multiplier that multiplies each other can omit, and reduces the bit wide of computational complexity and intermediate object program, and does not bring obvious influence on the performance.
The 4th computing circuit 34, be coupled to the second and the 3rd computing circuit 32,33 to receive each steering signal relevant information, the 3rd channel information t3 is multiplied by the first pilot channel relevant information s1 to be deducted second channel information t2 again and is multiplied by the second pilot channel relevant information s2, again divided by the first channel information t1 be multiplied by deduct behind the 3rd channel information t3 second channel information t2 square, resulting frequency offset information is delivered to frequency synchronisation circuit to reduce receiving terminal and the nonsynchronous error of transmitting terminal frequency; The first channel information t1 is multiplied by the second pilot channel relevant information s2 to be deducted second channel information t2 again and is multiplied by the first pilot channel relevant information s1, again divided by the first channel information t1 be multiplied by deduct behind the 3rd channel information t3 second channel information t2 square, resulting sample offset information is delivered to the sample-synchronous circuit to reduce receiving terminal and transmitting terminal nonsynchronous error of sampling.
Similarly, in this embodiment, also can run into the problem of information accuracy and computational complexity, also can adopt the method that splits computing, with difficulty that lowers the multiplication and division computing and the accuracy of possessing information.
Though the present invention illustrates and describes as embodiment with one or more specific example at this, details shown in but should not limiting the invention to, however still can not deviate under the spirit of the present invention and in the field of claim equalization and scope, realize many different modifications and structural change.Therefore, preferably the claim of being enclosed is explained widely and with the method that meets field of the present invention.
Claims (23)
1. method that detects carrier frequency shift and sampling frequency deviation in the ofdm system is characterized in that the method for carrier frequency shift and sampling frequency deviation comprises following steps in the described detection ofdm system:
Received signal is carried out FFT handle, obtain frequency-domain information, interior adjacent two code elements of frequency-domain information that will have each subcarrier of steering signal are again carried out related operation, obtain each steering signal relevant information;
To have the channel frequency response energy addition of each subcarrier of steering signal, obtain first channel information;
Described channel frequency response energy with each subcarrier of steering signal is multiplied by addition again after separately the channel designator respectively, obtains second channel information;
After described channel frequency response energy with each subcarrier of steering signal was multiplied by described channel designator separately square respectively, addition again obtained the 3rd channel information;
The phase information of described each steering signal relevant information is multiplied by described channel frequency response energy addition again with each subcarrier of steering signal respectively, obtains the first pilot channel relevant information;
After the phase information of described each steering signal relevant information being multiplied by the channel frequency response energy and channel designator of described each subcarrier with steering signal respectively, addition again obtains the second pilot channel relevant information;
After described the 3rd channel information is multiplied by the described first pilot channel relevant information earlier, the product that deducts described second channel information and the described second pilot channel relevant information again is to obtain one first difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one second difference, described first difference divided by described second difference to obtain the detection relevant information of frequency shift (FS);
After described first channel information is multiplied by the described second pilot channel relevant information earlier, the product that deducts described second channel information and the described first pilot channel relevant information again is to obtain one the 3rd difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one the 4th difference, described the 3rd difference divided by described the 4th difference to obtain the detection relevant information of sample offset.
2. the method for carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 1, carry out related operation after resulting described each steering signal relevant information contain phase information.
3. the method for carrier frequency shift and sampling frequency deviation in the detection ofdm system according to claim 1, it is characterized in that the accuracy of the described information of bit width sufficient to guarantee of described first, second and the 3rd channel information and described first and second pilot channel relevant information.
4. the method for carrier frequency shift and sampling frequency deviation in the detection ofdm system according to claim 3, it is characterized in that the bit width of described first, second and the 3rd channel information and described first and second pilot channel relevant information is more than 10.
5. the method for carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 1, utilizes the fractionation computing to assist to carry out the multiplication and division computing.
6. the method for carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 1, utilizes each subcarrier to transmit high exponent number quadrature amplitude modulation modulating signal.
7. the method for carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 6, utilizes each subcarrier transmission 64QAM signal.
8. the method for carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 1, and described ofdm system meets DVB-T standard or DAB standard.
9. circuit that detects carrier frequency shift and sampling frequency deviation in the ofdm system is characterized in that the circuit of carrier frequency shift and sampling frequency deviation comprises in the described detection ofdm system:
First computing circuit carries out FFT with received signal and handles in the frequency-domain information of each subcarrier that has steering signal in the frequency-domain information of back gained adjacent two code elements and carry out related operation, obtains each steering signal relevant information;
Second computing circuit will have the channel frequency response energy addition of each subcarrier of steering signal, obtain first channel information;
The 3rd computing circuit is multiplied by addition again after separately the channel designator respectively with described channel frequency response energy with each subcarrier of steering signal, obtains second channel information;
The 4th computing circuit, described channel frequency response energy with each subcarrier of steering signal is multiplied by described channel designator separately square respectively after, addition again obtains the 3rd channel information;
The 5th computing circuit is multiplied by described channel frequency response energy addition again with each subcarrier of steering signal respectively with the phase information of described each steering signal relevant information, obtains the first pilot channel relevant information;
The 6th computing circuit, the phase information of described each steering signal relevant information is multiplied by the channel frequency response energy and channel designator of described each subcarrier with steering signal respectively after, addition again obtains the second pilot channel relevant information; And
The 7th computing circuit, after described the 3rd channel information is multiplied by the described first pilot channel relevant information earlier, the product that deducts described second channel information and the described second pilot channel relevant information again is to obtain one first difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one second difference, the frequency offset information that described first difference obtains divided by described second difference is delivered to frequency synchronisation circuit to reduce receiving terminal and the nonsynchronous error of transmitting terminal frequency; After described first channel information is multiplied by the described second pilot channel relevant information earlier, the product that deducts described second channel information and the described first pilot channel relevant information again is to obtain one the 3rd difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one the 4th difference, the sample offset information that described the 3rd difference is obtained divided by described the 4th difference is delivered to the sample-synchronous circuit to reduce receiving terminal and transmitting terminal nonsynchronous error of sampling.
10. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 9, carry out related operation after resulting described each steering signal relevant information contain phase information.
11. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 9, described first to the 7th computing circuit utilization splits computing and reduces computational complexity.
12. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 9, the multiplier in described first to the 7th computing circuit is not more than 10.
13. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 9, utilizes each subcarrier to transmit high exponent number quadrature amplitude modulation modulating signal.
14. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 13, utilizes each subcarrier transmission 64QAM signal.
15. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 9, described ofdm system meets DVB-T standard or DAB standard.
16. a circuit that detects carrier frequency shift and sampling frequency deviation in the ofdm system is characterized in that the circuit of carrier frequency shift and sampling frequency deviation comprises in the described detection ofdm system:
First computing circuit carries out FFT with received signal R and handles in the frequency-domain information of each subcarrier that has steering signal in the frequency-domain information of back gained adjacent two code elements and carry out related operation, obtains each steering signal relevant information;
Second computing circuit, the phase information of described each steering signal relevant information is obtained the first pilot channel relevant information with adding up after relative each sub-carrier frequencies response energy multiplies each other, after the phase information of described each steering signal relevant information is multiplied by relative each sub-carrier frequencies response energy and its subcarrier sequence number, add up again, obtain the second pilot channel relevant information;
The 3rd computing circuit, the channel frequency response energy addition that will have each subcarrier of steering signal, obtain first channel information, described channel frequency response energy with each subcarrier of steering signal is multiplied by addition again after separately the channel designator respectively, obtain second channel information, after described channel frequency response energy with each subcarrier of steering signal was multiplied by described channel designator separately square respectively, addition again obtained the 3rd channel information;
The 4th computing circuit, after described the 3rd channel information is multiplied by the described first pilot channel relevant information earlier, the product that deducts described second channel information and the described second pilot channel relevant information again is to obtain one first difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one second difference, the frequency offset information that described first difference obtains divided by described second difference is delivered to frequency synchronisation circuit to reduce receiving terminal and the nonsynchronous error of transmitting terminal frequency; After described first channel information is multiplied by the described second pilot channel relevant information earlier, the product that deducts described second channel information and the described first pilot channel relevant information again is to obtain one the 3rd difference, the product of described first channel information and described the 3rd channel information deduct described second channel information square obtaining one the 4th difference, the sample offset information that described the 3rd difference is obtained divided by described the 4th difference is delivered to the sample-synchronous circuit to reduce receiving terminal and transmitting terminal nonsynchronous error of sampling.
17. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 16, carry out related operation after resulting described each steering signal relevant information contain phase information.
18. the circuit of carrier frequency shift and sampling frequency deviation in the detection ofdm system according to claim 16, it is characterized in that the accuracy of the described information of bit width sufficient to guarantee of described first, second and the 3rd channel information and described first and second pilot channel relevant information.
19. the circuit of carrier frequency shift and sampling frequency deviation in the detection ofdm system according to claim 18, it is characterized in that the bit width of described first, second and the 3rd channel information and described first and second pilot channel relevant information is more than 10.
20. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 18, utilizes the fractionation computing to assist to carry out the multiplication and division computing.
21. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 18, utilizes each subcarrier to transmit high exponent number quadrature amplitude modulation modulating signal.
22. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 21, utilizes each subcarrier transmission 64QAM signal.
23. the circuit of carrier frequency shift and sampling frequency deviation is characterized in that in the detection ofdm system according to claim 18, described ofdm system meets DVB-T standard or DAB standard.
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| CN1175171A (en) * | 1997-07-24 | 1998-03-04 | 北京信威通信技术有限公司 | Method for device of carrier exalting and compensating in frequency spreading communication system |
| US6198782B1 (en) * | 1999-02-11 | 2001-03-06 | Motorola, Inc. | Estimation of frequency offsets in OFDM communication systems |
| US6704374B1 (en) * | 2000-02-16 | 2004-03-09 | Thomson Licensing S.A. | Local oscillator frequency correction in an orthogonal frequency division multiplexing system |
| CN1574821A (en) * | 2003-06-20 | 2005-02-02 | 三星电子株式会社 | TDS-OFDM receiver and signal processing method thereof |
| CN1816032A (en) * | 2005-02-04 | 2006-08-09 | 三星电子株式会社 | Apparatus and method for compensating for a frequency offset in a wireless communication system |
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| CN1175171A (en) * | 1997-07-24 | 1998-03-04 | 北京信威通信技术有限公司 | Method for device of carrier exalting and compensating in frequency spreading communication system |
| US6198782B1 (en) * | 1999-02-11 | 2001-03-06 | Motorola, Inc. | Estimation of frequency offsets in OFDM communication systems |
| US6704374B1 (en) * | 2000-02-16 | 2004-03-09 | Thomson Licensing S.A. | Local oscillator frequency correction in an orthogonal frequency division multiplexing system |
| CN1574821A (en) * | 2003-06-20 | 2005-02-02 | 三星电子株式会社 | TDS-OFDM receiver and signal processing method thereof |
| CN1816032A (en) * | 2005-02-04 | 2006-08-09 | 三星电子株式会社 | Apparatus and method for compensating for a frequency offset in a wireless communication system |
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