CN101132386A - Interference restraining method for orthogonal frequency division multiplexing signal - Google Patents
Interference restraining method for orthogonal frequency division multiplexing signal Download PDFInfo
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- CN101132386A CN101132386A CNA2007100714143A CN200710071414A CN101132386A CN 101132386 A CN101132386 A CN 101132386A CN A2007100714143 A CNA2007100714143 A CN A2007100714143A CN 200710071414 A CN200710071414 A CN 200710071414A CN 101132386 A CN101132386 A CN 101132386A
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Abstract
This invention relates to a method for suppressing interference in OFDM signals including: segmenting received OFDM signals according to the order of data flows and superposing n data for the segments, carrying out FFT conversion to data of each segment to get frequency domain data of the received signals and computing mean power of the frequency domain to set three thresholds according to the mean power, comparing the power of the frequency domain with the three thresholds to test out interference to be screened. This invention provides a frequency domain process method for single frequency and shared frequency interference in the OFDM signals.
Description
Technical field
The invention belongs to digital signal transmission field, inhibition method to disturbing in the ofdm signal in particularly a kind of digital quadrature frequency division multiplexing (OFDM) receiver.
Background technology
OFDM is a kind of transmission plan of multi-carrier modulation, and ofdm system adopts a large amount of mutually orthogonal subcarriers to carry out transfer of data.Narrow band interference such as low intensive single-frequency, same simulated television frequently only can be damaged a spot of subcarrier, and the data of most of subcarrier still remain intact.But in high-intensity single-frequency, can damage plurality of subcarriers with narrow band interference such as simulated televisions frequently, cause taking defeat.In the symbol synchronization process of ofdm system, middle high strength is disturbed can influence correlation of data, can cause the data of OFDM to have correlation everywhere, rather than only just has correlation in the data of Cyclic Prefix or suffix, can cause the sign synchronization of OFDM to be failed.
Summary of the invention
The object of the present invention is to provide a kind of disturbance restraining method of ofdm signal, can effectively eliminate the influence of interference such as single-frequency, same simulated television frequently the OFDM receiver.
The present invention proposes the interference mitigation technology that a kind of frequency domain is handled.The time domain OFDM signal that receives is transformed to detection and the shielding that frequency domain disturbs, eliminate and disturb the influence that brings, time domain is returned in conversion again.
The interference mitigation technology of ofdm signal of the present invention may further comprise the steps:
At first the orthogonal frequency-division multiplex singal that receives is carried out segmentation according to the order of data flow, every segment data comprises M data of order, M=2
nBack one piece of data with the last period M-N+1 data as the segmentation starting point, the overlapping N of a front and back section data; Every segment data is carried out FFT (fast Flourier) conversion, obtain the frequency domain data x of received signal
i
According to frequency domain data x
iCalculate frequency domain data x
iPower p
i=| x
i|
2, to p
iCarry out low-pass filtering, low-pass filtering adopts IIR (infinite impulse response) low pass filter, and its filtering equations is y (n)=A * y (n-1)+x (n), and the result of low-pass filtering is as average power P; Set three thresholding T
1, T
2And T
3, T
1=P * k
1, T
2=P * k
2, T
3=P * k
3, k wherein
2＞k
1, k
2＞k
3
Power p with frequency domain data
iCompare with three thresholdings setting, greater than thresholding T
1For the strong jamming point, these data are suppressed, it is forced to zero, the influence of interference-shielded; If the power p of frequency domain data
iGreater than thresholding T
2, with the power p of each Q point data before and after this point data
iWith thresholding T
3Relatively, if greater than thresholding T
3Think to disturb, it is forced to zero, the influence of interference-shielded.
Frequency domain data after the interference-shielded is carried out IFFT (contrary fast Flourier) conversion, obtain time-domain signal, by digital AGC (automatic gain control) module inhibit signal power stability.
This method provides a kind of frequency domain technique to the single-frequency in the ofdm signal, co-channel interference, can detect single-frequency effectively and with frequently interference, and thoroughly eliminate single-frequency and co-channel interference, guaranteed in the receiver be not subjected to single-frequency synchronously and with influence frequently.
Description of drawings
Fig. 1 is the data sementation schematic diagram in the inventive method;
Fig. 2 detects in the inventive method and inhibition interference schematic diagram.
Embodiment
Enter the FFT/IFFT module behind the buffer of input data through two table tennis selections among the present invention and carry out the FFT conversion, enter Interference Detection again and suppress the shielding that module is disturbed, return the FFT/IFFT module afterwards and carry out the IFFT conversion, the last power stability that keeps shielding back signal again by digital AGC.
Input signal carries out segmentation according to the order of data flow, every segment data comprises M data of order, back one piece of data with the last period M-N+1 data as the segmentation starting point, the overlapping N of a front and back section data, owing to when carrying out the FFT conversion, have new data to bring, the data of twice FFT conversion simultaneously need N point lap (0＜N＜M), therefore importing data will be introduced into two buffers to carry out ping-pong operation, will enter two bufferings simultaneously in the lap data, each buffer is filled with just to read after the data and carries out the FFT computing.The input data overlapping relation of two bufferings as shown in Figure 1, FIFO_en0, FIFO_en1 are that FIFO writes and enables, the final data of FFT is identical with the most preceding data of FFT next time each time.
As Fig. 2, be the signal power statistics module in the frame of broken lines, signal power is carried out the IIR low pass filter, the IIR low pass filter adopts y (n)=0.999 * y (n-1)+x (n).k
1, k
2, k
3Get 10,15,5 respectively, respectively corresponding thresholding T
1, T
2And T
3If the power of frequency domain data surpasses thresholding T
1, just think to disturb, it is forced to zero, shield the influence of this interference.If the power of frequency domain data surpasses thresholding T
2, with the power and the thresholding T of each 3 point data before and after this point data
3Relatively, if surpass thresholding T
3Just think it also is to disturb, it is forced to zero.Interference shielding and the signal demand after the IFFT conversion are suppressed to disturb the power of back signal by the digital AGC module stability.
Claims (1)
1. orthogonal frequency-division multiplex singal suppresses the method for interference, it is characterized in that the concrete steps of this method are:
The orthogonal frequency-division multiplex singal that receives is carried out segmentation according to the order of data flow, and every segment data comprises M data of order, M=2
nBack one piece of data with the last period M-N+1 data as the segmentation starting point, the overlapping N of a front and back section data; Every segment data is carried out fast fourier transform, obtain the frequency domain data x of received signal
i
According to frequency domain data x
iCalculate frequency domain data x
iPower p
i=| x
i|
2, to p
iCarry out low-pass filtering, the filtering equations of low-pass filtering is y (n)=A * y (n-1)+x (n), and the result of low-pass filtering is as average power P; Set three thresholding T
1, T
2And T
3, T
1=P * k
1, T
2=P * k
2, T
3=P * k
3, k wherein
2＞k
1, k
2＞k
3
Power p with frequency domain data
iCompare with three thresholdings setting, greater than thresholding T
1For the strong jamming point, these data are suppressed, it is forced to zero, the influence of interference-shielded; If the power p of frequency domain data
iGreater than thresholding T
2, with the power p of each Q point data before and after this point data
iWith thresholding T
3Relatively, if greater than thresholding T
3Think to disturb, it is forced to zero, the influence of interference-shielded;
Frequency domain data after the interference-shielded is carried out contrary fast fourier transform, obtain time-domain signal, by digital Auto Gain control module inhibit signal power stability.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710071414 CN101132386B (en) | 2007-09-24 | 2007-09-24 | Interference restraining method for orthogonal frequency division multiplexing signal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710071414 CN101132386B (en) | 2007-09-24 | 2007-09-24 | Interference restraining method for orthogonal frequency division multiplexing signal |
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| Publication Number | Publication Date |
|---|---|
| CN101132386A true CN101132386A (en) | 2008-02-27 |
| CN101132386B CN101132386B (en) | 2013-01-30 |
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Cited By (7)
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|---|---|---|---|---|
| WO2010135946A1 (en) * | 2009-05-27 | 2010-12-02 | 中兴通讯股份有限公司 | Method and apparatus for realizing decimal frequency offset estimation |
| CN102006252A (en) * | 2010-11-30 | 2011-04-06 | 中国工程物理研究院电子工程研究所 | Single-tone signal identification method |
| CN102546505A (en) * | 2010-12-30 | 2012-07-04 | 联芯科技有限公司 | Automatic gain control method and device |
| CN101860509B (en) * | 2009-04-13 | 2012-10-10 | 扬智科技股份有限公司 | Method and device for processing co-channel interference and communication system thereof |
| CN102811190A (en) * | 2011-05-31 | 2012-12-05 | 上海明波通信技术股份有限公司 | Suppression method for single-frequency interference in OFDM (Orthogonal Frequency Division Multiplexing) communication system |
| CN103685126A (en) * | 2013-12-17 | 2014-03-26 | 中国联合网络通信集团有限公司 | Method for eliminating single-frequency interference and receiver |
| WO2014082263A1 (en) * | 2012-11-29 | 2014-06-05 | 华为技术有限公司 | Method and apparatus for processing signal |
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| CN1859346A (en) * | 2006-04-29 | 2006-11-08 | 北京理工大学 | Orthogonal frequency division mulplex system based on fractional order Fourier transformation |
| CN1992689A (en) * | 2005-12-31 | 2007-07-04 | 方正通信技术有限公司 | Method for improving inter-carrier interference of OFDM system |
| WO2007091562A1 (en) * | 2006-02-06 | 2007-08-16 | Sony Corporation | Demodulating device, method and program |
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| CN1490944A (en) * | 2003-09-19 | 2004-04-21 | 清华大学 | Sectional demodifying computing method for effectively reducing interfaces between sub-carrier |
| WO2006088326A2 (en) * | 2005-02-18 | 2006-08-24 | Lg Electronics Inc. | Wireless multiple access system for suppressing inter-cell interference |
| CN1992689A (en) * | 2005-12-31 | 2007-07-04 | 方正通信技术有限公司 | Method for improving inter-carrier interference of OFDM system |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101860509B (en) * | 2009-04-13 | 2012-10-10 | 扬智科技股份有限公司 | Method and device for processing co-channel interference and communication system thereof |
| WO2010135946A1 (en) * | 2009-05-27 | 2010-12-02 | 中兴通讯股份有限公司 | Method and apparatus for realizing decimal frequency offset estimation |
| CN101902426B (en) * | 2009-05-27 | 2012-12-19 | 中兴通讯股份有限公司 | Method and device for realizing decimal frequency deviation estimation |
| CN102006252B (en) * | 2010-11-30 | 2013-05-29 | 中国工程物理研究院电子工程研究所 | Single-tone signal identification method |
| CN102006252A (en) * | 2010-11-30 | 2011-04-06 | 中国工程物理研究院电子工程研究所 | Single-tone signal identification method |
| CN102546505A (en) * | 2010-12-30 | 2012-07-04 | 联芯科技有限公司 | Automatic gain control method and device |
| CN102546505B (en) * | 2010-12-30 | 2014-04-09 | 联芯科技有限公司 | Automatic gain control method and device |
| CN102811190A (en) * | 2011-05-31 | 2012-12-05 | 上海明波通信技术股份有限公司 | Suppression method for single-frequency interference in OFDM (Orthogonal Frequency Division Multiplexing) communication system |
| CN102811190B (en) * | 2011-05-31 | 2015-04-22 | 上海明波通信技术股份有限公司 | Suppression method for single-frequency interference in OFDM (Orthogonal Frequency Division Multiplexing) communication system |
| WO2014082263A1 (en) * | 2012-11-29 | 2014-06-05 | 华为技术有限公司 | Method and apparatus for processing signal |
| CN104137498A (en) * | 2012-11-29 | 2014-11-05 | 华为技术有限公司 | Method and apparatus for processing signal |
| CN104137498B (en) * | 2012-11-29 | 2018-02-06 | 华为技术有限公司 | A kind of signal processing method and device |
| CN103685126A (en) * | 2013-12-17 | 2014-03-26 | 中国联合网络通信集团有限公司 | Method for eliminating single-frequency interference and receiver |
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