CN1574820A - Time domain synchronous orthogonal frequency division multiplex receiving device and equalization method thereof - Google Patents
Time domain synchronous orthogonal frequency division multiplex receiving device and equalization method thereof Download PDFInfo
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- CN1574820A CN1574820A CNA2004100482960A CN200410048296A CN1574820A CN 1574820 A CN1574820 A CN 1574820A CN A2004100482960 A CNA2004100482960 A CN A2004100482960A CN 200410048296 A CN200410048296 A CN 200410048296A CN 1574820 A CN1574820 A CN 1574820A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B7/005—Control of transmission; Equalising
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Abstract
The invention relates to a TDS-OFDM receiving device using different equalizing methods according to channel status and a equalizing method, which comprises: a synchronous unit which is used to enable the OFDM signal according to the receiving of the antenna, transformation to baseband and the analog-digital conversion to be synchronous; a demultiplexer which is used to decompose the OFDM signal received from the synchronous element to a plurality of signals comprising the synchronous information and the OFDM code elements; a time domain equilibrium element which is used to use the OFDM code elements in the synchronous information equilibrium time domain; a first FFT unit which is used to transform the correlation of the synchronous information by the FFT; a second FFT unit which is used to transform the OFDM code elements by the FFT; a frequency domain equilibrium unit which is used to use the correlation of the synchronous information transformed in the first FFT unit to balance the OFDM code elements transformed in the second FFT unit; and a channel state confirmation unit which is used to calculate the correlation of the synchronous information to estimate the channel state, and choose one of the time domain equilibrium unit and the frequency domain equilibrium unit for equilibrium based on the estimated channel state. So the receiving function is improved by choosing one of the time and the frequency domain equilibrium units according to channel state.
Description
Technical field
The present invention relates to a kind of time-domain synchronization OFDM (TDS-OFDM) receiving system that uses different equalizers according to channel status.More specifically, the present invention relates to a kind ofly use one of time-domain equalizer and frequency-domain equalizer to carry out balanced selectively and improve the TDS-OFDM receiving system and the equalization methods thereof of the reception of TDS-OFDM system according to channel status.
Background technology
The OFDM scheme will be converted to predetermined block-based parallel data with the code element row of series form input, and parallel code element is multiplexed to the subcarrier frequency that has nothing in common with each other.The OFDM scheme is used multicarrier, and these are very different with the conventional method of using single carrier.In multicarrier, each carrier wave has orthogonality each other.Orthogonality is meant that two carrier multiplication are zero characteristic, and this is to use the necessary condition of multicarrier.The OFDM scheme is mainly used fast Fourier transform (FFT) and invert fast fourier transformation (IFFT).Therefore, orthogonality and the FFT based on intercarrier realizes the OFDM scheme.
Ofdm signal comprises multicarrier, and each multicarrier has very little bandwidth.Therefore, the entire spectrum shape becomes square basically, correspondingly, compares frequency efficiency with the situation of using single carrier and has improved.In addition, because the waveform of the waveform of ofdm signal and white Gaussian noise is identical, transmits color with other broadcasting services such as line-by-line inversion (PAL) and order and compare with memory system (SECAM), ofdm signal has interference still less.
Recently, in order to improve the speed of terrestrial digital television (DTV) transmission system standard, proposed digital multimedia terrestrial broadcast (DMB-T), this is the new transmission standard of land DTV.Use the transmission system of DMB-T also to use the TDS-OFDM scheme.Inverse discrete Fourier transformer inverse-discrete/discrete Fourier transform (DFT) (IDFT/DFT) processor that the OFDM modulating unit uses 3780-to order.
Yet, on transmission channel, may produce multiple distorted signals according to channel status.Signal is subjected to the influence of the distortion that distortion especially produces owing to multipath very big, and distortion is fatal in digital broadcasting.For compensating distortion, for receiving terminal provides the mistake of equalizer with the compensation transmission channel.
Fig. 1 is the block diagram of the TDS-OFDM receiving system of routine, and this device comprises: rf receiver unit (RF RX) 10, analog to digital converter (ADC) 12, lock unit 14, demultiplexer 16, pseudo noise (PN) correlation unit 20, a FFT unit 30, the 2nd FFT unit 40, frequency-domain balancing unit 50 and forward error correction device (FEC) unit 60.
Demultiplexer 16 will be decomposed into PN sequence, GI and OFDM code element and output from the OFDM broadcast singal that lock unit 14 receives.GI is inserted between PN sequence and the OFDM code element, to suppress the inter symbol interference (ISI) in the multi-path environment.
Be output to 40, the two FFT unit 40, the 2nd FFT unit by FFT conversion OFDM code element, to output to frequency-domain balancing unit 50 from the OFDM code element of demultiplexer 16 outputs.
Frequency-domain balancing unit 50 is based on the PN correlation that receives from a FFT unit 30, the OFDM code element of the balanced conversion that receives from the 2nd FFT unit 40.
As mentioned above, conventional TDS-OFDM receiving system uses the PN correlation to estimate channel status, and uses estimated channel state equalization frequency domain.Yet, when the information of channel status because distortion and noise component(s) and when inaccurate, equalization function worsens.
Summary of the invention
The objective of the invention is to address the above problem at least and/or shortcoming and the advantage that describes below at least is provided.Therefore, the object of the present invention is to provide a kind of time-domain synchronization OFDM (TDS-OFDM) receiving system and equalization methods thereof, this device uses one of time-domain equalizer and frequency-domain equalizer to carry out equilibrium according to channel status, and improves the receiving efficiency of TDS-OFDM system thus.
In order to realize above-mentioned aspect of the present invention, a kind of TDS-OFDM receiving system is provided, comprising: lock unit, be used for receive through antenna, downconvert to base band and through OFDM (OFDM) signal Synchronization of analog-to-digital conversion; Demultiplexer, the ofdm signal that is used for receiving from lock unit are decomposed into a plurality of signals that comprise synchronizing information and OFDM code element; The time domain equalization unit is used for using the OFDM code element of the balanced time domain of synchronizing information; The first fast Fourier transform (FFT) unit is used for the correlation by FFT conversion synchronizing information; The 2nd FFT unit is used for the code element by FFT conversion OFDM; Frequency-domain balancing unit is used to use the correlation in the synchronizing information of a FFT unit conversion, balanced OFDM code element in the 2nd FFT unit conversion; With the channel status determining unit, be used to calculate the correlation of synchronizing information, with the estimation channel status, and, select one of time domain equalization unit and frequency-domain balancing unit to be used for equilibrium based on the estimated channel state.
Lock unit uses synchronizing information, and synchronizing information is the PN sequence.
The time domain equalization unit is one of DFF (DFE), Kalman's equalizer and data recirculation (data recycling) equalizer.
The channel status determining unit is estimated the length and the time of delay of multipath, if length and time of delay, then select the time domain equalization unit respectively less than first and second threshold values, otherwise, select frequency-domain balancing unit.
A kind of equalization methods of TDS-OFDM receiving system comprises the steps: that (a) will receive, downconvert to base band through antenna and by the OFDM of analog-to-digital conversion (OFDM) signal Synchronization; (b) synchronous ofdm signal is decomposed into a plurality of signals that comprise synchronizing information and OFDM code element; (c) correlation of calculating synchronizing information to be estimating channel status, and selects one of time domain equalization pattern and frequency domain equalization pattern based on the estimated channel state; (d) when in step (c), selecting the time domain equalization pattern, use the OFDM code element in the balanced time domain of synchronizing information, and pass through the OFDM code element of FFT conversion equilibrium; (e) when in step (c), selecting the frequency domain equalization pattern, the correlation of conversion synchronizing information and OFDM code element, and the OFDM code element of the conversion in the balanced frequency domain of the correlation of the synchronizing information of use conversion.
Step (a) is used synchronizing information, and synchronizing information is the PN sequence.
Time domain equalization is one of decision feedback equalization (DFE), Kalman's equilibrium and data recirculation equilibrium.
Step (c) is estimated the length and the time of delay of multipath, if length and time of delay, then select the time domain equalization pattern respectively less than first and second threshold values, otherwise, select the frequency domain equalization pattern.
Description of drawings
By the detailed description that the reference accompanying drawing carries out exemplary embodiments of the present invention, above-mentioned purpose of the present invention and other characteristics will become apparent, wherein:
Fig. 1 is the block diagram of conventional TDS-OFDM receiving system;
Fig. 2 is the block diagram of the TDS-OFDM receiving system of embodiments of the invention; With
Fig. 3 be the expression embodiment of the invention use different equalization methods to carry out the flow chart of the equalization methods of balanced TDS-OFDM receiving system according to channel status.
It should be understood that label identical among the figure represents identical figure and structure.
Embodiment
Below, describe the present invention with reference to the accompanying drawings in detail.
Fig. 2 is the block diagram of the TDS-OFDM receiving system of the embodiment of the invention.With reference to Fig. 2, the TDS-OFDM receiving system comprises: rf receiver unit (RF RX) 100, ADC 120, lock unit 140, demultiplexer 160, channel status determining unit 200, first switch 210, second switch 220, a FFT unit 310, the 2nd FFT unit 320, time domain equalization unit 400, frequency-domain balancing unit 500 and FEC unit 600.
RF RX 100 will downconvert to base band through the OFDM broadcast singal that antenna receives, and ADC 120 will be digital signal from the analog signal conversion of RF RX 100.
Lock unit 140 uses the PN sequence that sends as synchronizing information to carry out symbol timing and Frequency Synchronization.
Demultiplexer 160 will be decomposed into PN sequence, GI and OFDM code element and output from the OFDM broadcast singal that lock unit 140 receives.
One of the time domain equalization unit 400 that provides in the channel status determining unit 200 selection TDS-OFDM receiving systems and frequency-domain balancing unit 500 are carried out equilibrium to use selecteed balanced unit.
Time domain equalization unit 400 uses the PN sequence usually, and this sequence is an OFDM broadcast singal synchronizing information.Balanced scope depends on the length of PN sequence.When having long multipath in the channel, time domain equalization unit 400 may not work fully.The frequency-domain balancing unit 500 of use PN correlation is not subjected to the influence of the multipath in the PN sequence length in equilibrium.Therefore, although there is long multipath in the channel, balanced efficient can not worsen.But 500 pairs of noises of frequency-domain balancing unit are very sensitive.
Therefore, channel status determining unit 200 is calculated the PN correlation that receives from demultiplexer 160, and uses the PN correlation to estimate the length and the time of delay of multipath in the channel.If the length of multipath is less than predetermined first threshold T
1, and time of delay is less than the second predetermined threshold value T
2, then channel status determining unit 200 is adjusted first and second switches 210 and 220, sending to time domain equalization unit 400 from the OFDM code element of the output of demultiplexer.Therefore, channel status determining unit 200 is provided with the path, thereby OFDM code element quilt in time domain equalization unit 400 is balanced, and is sent to FEC unit 600 by the 2nd FFT unit 320.On the other hand, the length when multipath is equal to or greater than first threshold T
1, or be equal to or greater than the second threshold value T time of delay of multipath
2, then channel status determining unit 200 is adjusted first and second switches 210 and 220 path is set, so that be sent to frequency-domain balancing unit 500 from the OFDM code element of demultiplexer 160 outputs by the 2nd FFT unit 320.Channel status determining unit 200 is based on the length of multipath and select one of two balanced units time of delay.Length and ghost image scope according to time domain equalization unit 400 manageable multipaths are determined length and time of delay.
Time domain equalization unit 400 uses the OFDM code element from the balanced time domain of PN sequence information that demultiplexer 160 receives.For time domain equalization unit 400, can adopt DFF (DFE), Kalman's equalizer and data recirculation equalizer.
When channel status determining unit 200 output PN correlations to a FFT unit 310, this correlation is the correlation of the information that is used for channel status that calculates between reference signal row and the PN sequence, the one FFT unit 310 passes through FFT conversion PN correlation, and it is outputed to frequency-domain balancing unit 500.The OFDM code element that frequency-domain balancing unit 500 receives from the 2nd FFT unit 320 based on the PN correlation equilibrium that receives from a FFT unit 310.
FEC unit 600 uses the corresponding error detection method to detect the mistake of balanced OFDM code element, and corrects detected mistake.
Fig. 3 be the expression embodiment of the invention use the flow chart of equalization methods of the TDS-OFDM receiving system of different equalization methods according to channel status.With reference to Fig. 3, the OFDM broadcast singal that receives through antenna is down converted to base band in RFRX 100, be converted to digital signal in ADC 120, quilt synchronous (S810) in lock unit 140.
Demultiplexer 160 will be decomposed into PN sequence, GI and OFDM code element and output (S820) from the OFDM broadcast singal that lock unit 140 receives.
Channel status determining unit 200 is calculated the PN correlation of the PN sequence that receives from demultiplexer 160, and uses the PN correlation to estimate the length and the time of delay (S830) of multipath in the channel.
If the length of multipath is less than predetermined first threshold T
1And time of delay is less than the second predetermined threshold value T
2, then channel status determining unit 200 is provided with the path, so that OFDM code element quilt balanced (S851) in time domain equalization unit 400 is transformed in the 2nd FFT unit 320, and sends to FEC unit 600 (S861) by the 2nd FFT unit 320.
On the other hand, the length when multipath is equal to or greater than first threshold T
1And be equal to or greater than the second threshold value T time of delay of multipath
2The time, channel status determining unit 200 is provided with the path, so that be sent to frequency-domain balancing unit 500 from the OFDM code element of demultiplexer 160 outputs by the 2nd FFT unit 320.Channel status determining unit 200 outputs to a FFT unit 310 with the PN correlation, so that the PN correlation is transformed and outputs to frequency-domain balancing unit 500 (S853).The OFDM code element that frequency-domain balancing unit 500 receives from the 2nd FFT unit 320 based on the PN correlation equilibrium that receives from a FFT unit 310.(S863)。
FEC unit 600 uses the corresponding error detection method to detect the mistake of balanced OFDM code element, and corrects detected mistake (S870).
Be appreciated that receiving efficiency from the description of the invention described above embodiment, in time domain equalization unit and frequency-domain balancing unit, select one according to channel status for the TDS-OFDM system that improves.Therefore, can solve the problem of conventional receiving system, promptly because conventional receiving system is only balanced and can not compensate the problem of the little multipath that is caused by correlation shake and noise in frequency domain.
Although represented and described the present invention with reference to its specific embodiment, it should be appreciated by those skilled in the art, under the situation that does not break away from the spirit and scope that are defined by the following claims, can do the modification of various forms and details.
Claims (10)
1, a kind of time-domain synchronization OFDM (TDS-OFDM) receiving system comprises:
Lock unit is used for and will receives, downconvert to base band through antenna and by the OFDM of analog-to-digital conversion (OFDM) signal Synchronization;
Demultiplexer, the ofdm signal that is used for receiving from lock unit are decomposed into a plurality of signals that comprise synchronizing information and OFDM code element;
The time domain equalization unit is used for using the OFDM code element of the balanced time domain of synchronizing information;
The first fast Fourier transform (FFT) unit is used for the correlation by FFT conversion synchronizing information;
The 2nd FFT unit is used for the code element by FFT conversion OFDM;
Frequency-domain balancing unit is used to use the correlation in the synchronizing information of a FFT unit conversion, balanced OFDM code element in the 2nd FFT unit conversion; With
Channel status determining unit, the correlation that is used to calculate synchronizing information to be estimating channel status, and select one of time domain equalization unit and frequency-domain balancing unit to be used for equilibrium based on the estimated channel state.
2, TDS-OFDM receiving system according to claim 1, wherein, lock unit uses synchronizing information.
3, TDS-OFDM receiving system according to claim 1, wherein, synchronizing information is the PN sequence.
4, TDS-OFDM receiving system according to claim 1, wherein, the time domain equalization unit is one of DFF (DFE), Kalman's equalizer and data recirculation equalizer.
5, TDS-OFDM receiving system according to claim 1, wherein, the channel status determining unit is estimated the length and the time of delay of multipath, if length and time of delay are respectively less than first and second threshold values, then select the time domain equalization unit, otherwise, frequency-domain balancing unit selected.
6, the equalization methods of a kind of time-domain synchronization OFDM (TDS-OFDM) receiving system comprises the steps:
(a) will receive, downconvert to base band and through antenna by the OFDM of analog-to-digital conversion (OFDM) signal Synchronization;
(b) synchronous ofdm signal is resolved into a plurality of signals that comprise synchronizing information and OFDM code element;
(c) correlation of calculating synchronizing information to be estimating channel status, and selects one of time domain equalization pattern and frequency domain equalization pattern based on the estimated channel state;
(d) when in step (c), selecting the time domain equalization pattern, use the OFDM code element in the balanced time domain of synchronizing information, and pass through the OFDM code element of FFT conversion equilibrium; With
(e) when in step (c), selecting the frequency domain equalization pattern, the correlation of conversion synchronizing information and OFDM code element, and the OFDM code element of the conversion in the balanced frequency domain of the correlation of the synchronizing information of use conversion.
7, equalization methods as claimed in claim 6, wherein, step (a) is used synchronizing information.
8, equalization methods as claimed in claim 6, wherein, synchronizing information is the PN sequence.
9, equalization methods as claimed in claim 6, wherein, time domain equalization is one of decision feedback equalization (DFE), Kalman's equilibrium and data recirculation equilibrium.
10, equalization methods as claimed in claim 6, wherein, step (c) is estimated the length and the time of delay of multipath, if length and time of delay, then select the time domain equalization pattern respectively less than first and second threshold values, otherwise, select the frequency domain equalization pattern.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020030039579A KR20040110341A (en) | 2003-06-18 | 2003-06-18 | TDS-OFDM receiver for using different equalizers according to channel status and method for equalizing of TDS-OFDM receiver |
| KR39579/2003 | 2003-06-18 |
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| CN1574820A true CN1574820A (en) | 2005-02-02 |
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| CNA2004100482960A Pending CN1574820A (en) | 2003-06-18 | 2004-06-18 | Time domain synchronous orthogonal frequency division multiplex receiving device and equalization method thereof |
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Cited By (6)
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| WO2009012630A1 (en) * | 2007-07-25 | 2009-01-29 | Zte Corporation | Receiver and method for multi-user interfere eliminating based on frequency domain equalization combined with time domain |
| CN101854316A (en) * | 2009-03-30 | 2010-10-06 | 华为技术有限公司 | Method for electrical equalization and electrical depolarization, receiving end device and communication system |
| CN101305608B (en) * | 2005-11-07 | 2010-10-13 | Lg电子株式会社 | Apparatus for receiving a signal of orthogonal frequency division multiplexing |
| CN101146082B (en) * | 2006-09-12 | 2012-08-08 | 索尼株式会社 | OFDM receiver and OFDM signal receiving method |
| CN101164309B (en) * | 2005-03-10 | 2015-04-08 | 高通股份有限公司 | Method and device for placing collection window for FFT |
| CN105450557A (en) * | 2014-06-17 | 2016-03-30 | 北京司响无限文化传媒有限公司 | Air sound wave communication channel equalization method and device based on channel characteristics |
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| KR100793789B1 (en) * | 2006-03-09 | 2008-01-11 | 엘지전자 주식회사 | An apparatus for estimating channel and a method thereof |
| KR100849799B1 (en) * | 2006-11-28 | 2008-07-31 | 삼성전기주식회사 | Ofdm receiver co-using time and frequency domain equalizing and time domain equalizer |
| KR100909279B1 (en) | 2007-08-07 | 2009-07-27 | 한국전자통신연구원 | Demodulation Device and Method in Transmission System |
| KR101005843B1 (en) * | 2009-05-11 | 2011-01-05 | 한국해양연구원 | Method and Apparatus for the Hybrid Augmented Channel Equalization of the Receiver for Underwater Acoustic Communication |
| US11316598B2 (en) * | 2017-12-28 | 2022-04-26 | Intel Corporation | Method and apparatus for low power synchronization of bluetooth systems |
-
2003
- 2003-06-18 KR KR1020030039579A patent/KR20040110341A/en not_active Application Discontinuation
-
2004
- 2004-06-18 CN CNA2004100482960A patent/CN1574820A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101164309B (en) * | 2005-03-10 | 2015-04-08 | 高通股份有限公司 | Method and device for placing collection window for FFT |
| CN101305608B (en) * | 2005-11-07 | 2010-10-13 | Lg电子株式会社 | Apparatus for receiving a signal of orthogonal frequency division multiplexing |
| CN101146082B (en) * | 2006-09-12 | 2012-08-08 | 索尼株式会社 | OFDM receiver and OFDM signal receiving method |
| WO2009012630A1 (en) * | 2007-07-25 | 2009-01-29 | Zte Corporation | Receiver and method for multi-user interfere eliminating based on frequency domain equalization combined with time domain |
| CN101854316A (en) * | 2009-03-30 | 2010-10-06 | 华为技术有限公司 | Method for electrical equalization and electrical depolarization, receiving end device and communication system |
| WO2010111897A1 (en) * | 2009-03-30 | 2010-10-07 | 华为技术有限公司 | Electronic equalization and electronic depolarization method, receiving end equipment and communication system |
| US8218614B2 (en) | 2009-03-30 | 2012-07-10 | Huawei Technologies Co., Ltd. | Electronic equalization and electronic depolarization method, receiving end equipment, and communication system |
| CN105450557A (en) * | 2014-06-17 | 2016-03-30 | 北京司响无限文化传媒有限公司 | Air sound wave communication channel equalization method and device based on channel characteristics |
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| KR20040110341A (en) | 2004-12-31 |
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