CN1466287A - Transmitting system and method for modulating transmitted signal by OFDM - Google Patents
Transmitting system and method for modulating transmitted signal by OFDM Download PDFInfo
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- CN1466287A CN1466287A CNA021432821A CN02143282A CN1466287A CN 1466287 A CN1466287 A CN 1466287A CN A021432821 A CNA021432821 A CN A021432821A CN 02143282 A CN02143282 A CN 02143282A CN 1466287 A CN1466287 A CN 1466287A
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- ofdm
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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
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0041—Arrangements at the transmitter end
-
- 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
- H04L27/2602—Signal structure
- H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
Abstract
An OFDM transmission system capable of transmitting OFDM signals of a multiple service mode through allotted channels is provided to increase the use efficiency of allotted frequency bandwidth by transmitting source data corresponding to a plurality of service modes. A plurality of forward error connection(FEC) units(100) execute coding for correcting errors generated in transmitting a plurality of source data according to service modes. A plurality of mapping units(200) map the error-coded source data by symbol units. A frame forming unit(300) combines the mapped source data for forming one orthogonal frequency division multiplexing(OFDM) frame. An inverse fast fourier transform(IFFT) unit(500) executes IFFT by allotting multiple subcarriers to the OFDM frame by source data. A guard interval(GI) insertion unit(600) inserts a guard interval into the OFDM frame to prevent interferences between OFDM frames.
Description
Invention field
The present invention relates to a kind of OFDM (OFDM) emission system and corresponding OFDM launching technique, relate in particular to a kind of OFDM emission system and corresponding OFDM launching technique, the ofdm signal after by the OFDM modulation signal that is launched also will being modulated is inserted in a plurality of subcarriers and transmits.
Background technology
High definition TV (HDTV) broadcast system mainly comprises video encoder and modulator.The digital data compression of about 1Gbps that video encoder will obtain from high-definition video source is to the data of 15-18Mbps.Modulator is launched the numerical data of these several 10Mbps to the recipient by the limited frequency band channel of about 6-8MHz.The terrestrial broadcast system of using VHF (the very high frequency(VHF))/UHF (hyperfrequency) that distributes to television broadcasting is adopted in digital HDTV broadcasting.
In Europe, adopt OFDM (OFDM) method as the high definition TV terrestrial broadcast system, wherein, the OFDM method is a kind of Ditital modulation method of the double effects that is used to obtain to improve every bandwidth for transmission speed and prevents to disturb.
In the OFDM method, the code element stream of serial input is transformed to the parallel data of predetermined cell block.This paralleled code element a plurality ofly has the subcarrier of different frequency respectively by multiplexed by using.Such OFDM method is used a plurality of carrier waves, with traditional single carrier transmission method in essence different is arranged.Orthogonal between these a plurality of carrier waves.Orthogonality means a kind of feature, and promptly two carrier multiplication will be " zero ", and this is to use the requirement of these a plurality of carrier waves.This OFDM method by fast Fourier transform (FFT) and simply the inverse fast Fourier transform (IFFT) that obtains of the definition by orthogonality between subcarrier and FFT realize.
Simultaneously, the advantage of OFDM method is as follows:
The TV method of terrestrially transmitting of the characteristic of channel that is determined as have that transmission quality is disturbed by the reflected wave that produces in the signals transmission, cochannel and adjacent-channel interference etc., so the design condition of this transmission system is very complicated.On the contrary, OFDM is powerful for multipath.That is, because use a plurality of carrier waves, the code element transmission time can be increased.This makes OFDM more blunt for the caused interference signal of multipath comparatively speaking, has therefore prevented to be worsened by long echo-signal.And OFDM also is powerful for existing signal, and having prevented is influenced by the cochannel interference.Because these characteristics can configuring single-frequency network network (SFN).Here SFN mean single broadcast by single frequency to home broadcasting.This causes that greatly cochannel disturbs, and therefore can use the OFDM method, because it is very powerful for such environment.By this way, SFN can use limited frequency resource effectively.
Simultaneously, ofdm signal is made up of a plurality of carrier waves, and each carrier wave has very narrow frequency band.Because a plurality of spectrums of carrier have the waveform near rectangle, therefore has higher relatively frequency efficiency than single carrier wave.In addition, in the OFDM method situation below is favourable, promptly because the waveform of ofdm signal is identical with white Gaussian noise (WGN), ofdm signal is compared with other form as the broadcasting service of line-by-line inversion (PAL), forsequential color and storage (SECAM) etc., produces less interference.Therefore, in the OFDM method, each carrier wave can use different modulator approach modulation, therefore can realize hierarchical transmission.
Fig. 1 has schematically shown common OFDM emission system.
This OFDM emission system comprises that a FEC (forward error correction) coding unit 10, IFFT (inverse fast Fourier transform) unit 20, a GI (protection at interval) insert unit 30 and a RF (radio frequency) up-conversion unit 40.
Coding is carried out in FEC error correction coding unit 10, is used for proofreading and correct the error code that the source data of scheduled transmission business model takes place in transmission course.Source data after the 20 pairs of error correction codings in IFFT unit is carried out inverse Fourier transform.GI inserts unit 30 and inserts a protection at interval, is used to suppress the interference between the source data after the inverse Fourier transform.RF up-conversion unit 40 will insert protection source data at interval and up-convert to radiofrequency signal., launched to the recipient through antenna 50 by the source data of up-conversion by transmission channel.
Fig. 2 shows giving an example by the frame structure of the data of traditional OFDM emission system emission.In the drawings, business model is illustrated as mpeg data.
The frame structure of the mpeg data by the emission of traditional OFDM emission system is to belong in IFFT unit 20, is used to the type of a plurality of subcarrier inverse Fourier transforms of the predetermined N number of fast Fourier transform.At this moment, this mpeg data comprises the frame with the predetermined N number similar number of a plurality of subcarriers.
The a plurality of subcarriers of traditional OFDM emission system by predetermined number are emitted as a kind of source data of predetermined business model, only launch single business, and no matter according to the desired transmission speed of business model.Therefore, traditional OFDM emission system inverse Fourier transform source data, promptly a kind of business model and with its emission, and no matter a plurality of subcarriers of predetermined number.Therefore, because responding a kind of business model emission source data, traditional OFDM emission system, can not use a plurality of subcarriers of predetermined number effectively regardless of the business model of the source data that will be launched.
In addition, because traditional OFDM emission system is to the source data of the predetermined frequency band emission that is used for a kind of business model corresponding to business model, the service efficiency of predetermined frequency band is very low, unless the source data of emission corresponding service pattern.
Summary of the invention
Therefore, one object of the present invention is, provides a kind of according to business model, can effectively utilize the OFDM emission system and the corresponding OFDM launching technique of predetermined frequency band more.
Another object of the present invention is to, provide a kind of and can pass through predetermined band transmission corresponding to the corresponding OFDM launching technique of the OFDM emission system of the ofdm signal of more miscellaneous service pattern.
For achieving the above object, the invention provides a kind of OFDM (OFDM) emission system, by OFDM modulate emission signal, this system comprises: a plurality of forward error corrections (FEC) coding unit, be used for the multiple source data corresponding to a plurality of business models are carried out coding, so that the error code at the receiver place that takes place in the correction data transmission, wherein, each FEC coding unit is carried out the coding corresponding to a kind of source data of business model; A plurality of map unit, link to each other corresponding with described a plurality of FEC coding units, each map unit is used for the source data after the respective coding is mapped as code element; One becomes frame unit, be used for to be a plurality of OFDM frames by the grouping of bits after described a plurality of map unit mappings, these a plurality of OFDM frames are divided into the frame group of predetermined number, and in each frame group, insert a letter head, wherein, the letter head comprises about being included in the information of each source data in a plurality of business models in the OFDM frame in groups; An inverse fast Fourier transform (IFFT) unit is by described OFDM frame being carried out the inverse fast Fourier transform of a plurality of subcarriers, so that described OFDM frame is modulated to the OFDM code element; The unit is inserted in protection at interval (GI), is used for inserting between the OFDM code element being used to the protection that suppresses to disturb (GI) at interval; And a radio frequency (RF) up-conversion unit, be used for up-converting to radiofrequency signal with inserting GI OFDM code element afterwards.
Best, described OFDM emission system comprises that also a protection frequency band (GB) inserts the unit, is used for inserting the protection frequency band in the both sides of an OFDM frame that is formed by described one-tenth frame unit.
The type of described source data comprises mpeg data, voice data and datacast data.
The number of a plurality of subcarriers that is used for inverse Fourier transform is respectively corresponding to any one of 2048 2K, 4096 4K and 8192 s' 8K.
According to another aspect of the present invention, the OFDM launching technique of a kind of OFDM of utilization emission system by OFDM modulate emission signal is provided, this method may further comprise the steps: the multiple source data corresponding to a plurality of business models are carried out coding, so that the error code that takes place in the correction data transmission at the receiver place, wherein, carry out by a FEC coding unit corresponding to a kind of coding of source data of business model; Source data after the respective coding is mapped as corresponding code element; To be a plurality of OFDM frames by the grouping of bits after described a plurality of map unit mappings, these a plurality of OFDM frames are divided into the frame group of predetermined number, and in each frame group, insert a letter head, wherein, the letter head comprises about being included in the information of each source data in a plurality of business models in the OFDM frame in groups; By described OFDM frame being carried out the inverse fast Fourier transform of a plurality of subcarriers, so that described OFDM frame is modulated to the OFDM code element; Between the OFDM code element, insert and be used to the protection that suppresses to disturb (GI) at interval; And the OFDM code element that will insert after the GI up-converts to radiofrequency signal.
Best, in above-mentioned OFDM launching technique, insert protection frequency band (GB) in the both sides of an OFDM frame.
The type of described source data comprises mpeg data, voice data and datacast data.
The number of a plurality of subcarriers that is used for inverse Fourier transform is respectively corresponding to any one of 2048 2K, 4096 4K and 8192 s' 8K.
According to the present invention, by launch source data with predetermined frequency band, can improve the utilization ratio of predetermined frequency band, and can provide various widely business by frequency band corresponding to the multiple business pattern.
Description of drawings
Following detailed description in conjunction with the drawings, above-mentioned purpose of the present invention, characteristic and advantage will be more obvious, wherein:
Fig. 1 has schematically shown the block diagram of common OFDM emission system;
Fig. 2 shows the frame structure by the data of traditional OFDM emission system emission;
Fig. 3 shows the block diagram according to the OFDM emission system of the preferred embodiments of the present invention;
Fig. 4 shows giving an example as the OFDM frame that forms among Fig. 3;
Fig. 5 shows the figure from a plurality of OFDM frames of the one-tenth frame unit of Fig. 3 output along time shaft;
Fig. 6 shows according to the preferred embodiments of the present invention, utilizes the flow chart of the OFDM launching technique of OFDM emission system.
Embodiment
Now with reference to accompanying drawing the preferred embodiments of the present invention are described.
Fig. 3 shows the block diagram according to the OFDM emission system of the preferred embodiments of the present invention.
This OFDM emission system comprises: a plurality of FEC (forward error correction) coding unit 100; a plurality of map unit 200; a plurality of one-tenth frame units 300; a GB (protection frequency band) inserts unit 400; an IFFT (inverse fast Fourier transform) unit 500; a GI (protection at interval) inserts unit 600, and a RF (radio frequency) up-conversion unit 700.
RF up-conversion unit 700 will insert protection ofdm signal at interval and up-convert to radiofrequency signal.Ofdm signal behind this RF up-converter is launched by transmission channel through antenna 800.
Therefore, can be in predetermined bandwidth emission according to the ofdm signal of multiple business pattern.In addition, because the recipient receives multiple business, the business that can select and recover to want in an OFDM frame.In addition, because multiple business, can improve the utilization ratio of predetermined frequency band with a predetermined band transmission.
The one-tenth frame unit 300 of this embodiment preferably will form a plurality of OFDM frames corresponding to the source data of the business model of multiple input, then a plurality of OFDM frames will be divided into the group of predetermined number, and insert a letter head in each frame group.At this moment, this letter head comprises the information about each source data that is included in the multiple business pattern in the OFDM frame in groups.
Fig. 4 shows giving an example as the OFDM frame that forms among Fig. 3.According to the OFDM frame, comprise mpeg data, voice data and datacast data according to the source data of business model.The one-tenth frame unit 300 of this embodiment according to every kind of desired transmission speed of business model, is provided with the predetermined portions of mpeg data, voice data and datacast data, and corresponding source data is inserted in the predetermined portions.In the drawings, in an OFDM frame, mpeg data occupies maximum zone, and datacast data occupies second largest zone then, and voice data occupies the third-largest zone etc. then.
In addition, as shown in the figure, this OFDM frame has the shape of inserting unit 400 insertion protection frequency bands on the both sides of frame by GB.And corresponding OFDM frame is to be formed by the N number with 0 a plurality of subcarriers of counting to " N-1 " individual a plurality of subcarriers.At this moment, N comprises 2K, 4K and 8K.Therefore protect frequency band to be comprised in the middle of the number of corresponding a plurality of subcarriers of predetermined frequency band.
Fig. 5 shows the figure from a plurality of OFDM frames of the one-tenth frame unit of Fig. 3 output along time shaft.As shown in the figure, the number of quilt frame in groups is m in becoming frame unit 300.Therefore letter head (H) is inserted in groups m the OFDM frame.This letter head (H) comprise source data about each OFDM frame corresponding to every kind of business model (data broadcasting (1), audio frequency (1), MPEG (1), data broadcasting (2), audio frequency (2), MPEG (2) ... data broadcasting (m), audio frequency (m), MPEG (m)) information.
Therefore, the OFDM receiver receives has the insertion ofdm signal about the letter head of the information of the source data of OFDM frame wherein, by analyzed this letter head (H), the source data that can extract and recover to want before recovering the ofdm signal that receives.
Fig. 6 shows according to the preferred embodiments of the present invention, utilizes the flow chart of the OFDM launching technique of OFDM emission system.
At first, FEC coding unit 100 with a FEC coding unit 120, the 2nd FEC coding unit 140 and the 3rd FEC coding unit 160, corresponding to every kind of business model, carry out the coding be used for proofreading and correct the error code that the transmission course as the source data of mpeg data, voice data and datacast data takes place respectively.
According to the present invention,, can improve the utilization ratio of predetermined frequency band and can provide miscellaneous service widely by frequency band by with the source data of predetermined band transmission corresponding to the multiple business pattern.
Although the present invention is illustrated and is described with reference to its certain preferred embodiment, it will be understood by those of skill in the art that under the situation that does not break away from the spirit and scope that define in the appending claims, can carry out the modification on various forms and the details.
Claims (8)
1. an OFDM (OFDM) emission system, by OFDM modulate emission signal, this system comprises:
A plurality of forward error corrections (FEC) coding unit, be used for the multiple source data corresponding to a plurality of business models are carried out coding, so that the error code at the receiver place that takes place in the correction data transmission, wherein, each FEC coding unit is carried out the coding corresponding to a kind of source data of business model;
A plurality of map unit, link to each other corresponding with described a plurality of FEC coding units, each map unit is used for the source data after the respective coding is mapped as code element;
One becomes frame unit, be used for to be a plurality of OFDM frames by the grouping of bits after described a plurality of map unit mappings, these a plurality of OFDM frames are divided into the frame group of predetermined number, and in each frame group, insert a letter head, wherein, the letter head comprises about being included in the information of each source data in a plurality of business models in the OFDM frame in groups;
An inverse fast Fourier transform (IFFT) unit is by described OFDM frame being carried out the inverse fast Fourier transform of a plurality of subcarriers, so that described OFDM frame is modulated to the OFDM code element;
The unit is inserted in protection at interval (GI), is used for inserting between the OFDM code element being used to the protection that suppresses to disturb (GI) at interval; And
A radio frequency (RF) up-conversion unit is used for up-converting to radiofrequency signal with inserting GI OFDM code element afterwards.
2. the system as claimed in claim 1 comprises that also a protection frequency band (GB) inserts the unit, is used for inserting the protection frequency band in the both sides of an OFDM frame that is formed by described one-tenth frame unit.
3. system as claimed in claim 2, wherein, described source data comprises at least a data in mpeg data, voice data and the datacast data.
4. system as claimed in claim 3, wherein, the number of a plurality of subcarriers that is used for carrying out inverse fast Fourier transform is respectively corresponding to any one of 2048 2K, 4096 4K and 8192 s' 8K.
5. one kind is utilized the OFDM launching technique of OFDM emission system by OFDM modulate emission signal, and this method may further comprise the steps:
To carrying out coding, so that the error code that takes place in the correction data transmission, wherein, carry out by a FEC coding unit corresponding to a kind of coding of source data of business model at the receiver place corresponding to the multiple source data of a plurality of business models;
Source data after the respective coding is mapped as corresponding code element;
To be a plurality of OFDM frames by the grouping of bits after described a plurality of map unit mappings, these a plurality of OFDM frames are divided into the frame group of predetermined number, and in each frame group, insert a letter head, wherein, the letter head comprises about being included in the information of each source data in a plurality of business models in the OFDM frame in groups;
By described OFDM frame being carried out the inverse fast Fourier transform of a plurality of subcarriers, so that described OFDM frame is modulated to the OFDM code element;
Between the OFDM code element, insert and be used to the protection that suppresses to disturb (GI) at interval; And
Up-convert to radiofrequency signal with inserting GI OFDM code element afterwards.
6. method as claimed in claim 6 also comprises step: insert protection frequency band (GB) in the both sides of an OFDM frame.
7. method as claimed in claim 6, wherein, described source data comprises at least a data in mpeg data, voice data and the datacast data.
8. method as claimed in claim 7, wherein, the number of a plurality of subcarriers that is used for inverse Fourier transform is respectively corresponding to any one of 2048 2K, 4096 4K and 8192 s' 8K.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020020033255A KR20030095709A (en) | 2002-06-14 | 2002-06-14 | OFDM Transmitting System capable of transmitting the OFDM signal of multi-service mode according to predetermined a channel |
| KR33255/2002 | 2002-06-14 | ||
| KR33255/02 | 2002-06-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1466287A true CN1466287A (en) | 2004-01-07 |
| CN1319299C CN1319299C (en) | 2007-05-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB021432821A Expired - Fee Related CN1319299C (en) | 2002-06-14 | 2002-09-25 | Transmitting system and method for modulating transmitted signal by OFDM |
Country Status (2)
| Country | Link |
|---|---|
| KR (1) | KR20030095709A (en) |
| CN (1) | CN1319299C (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101115184B (en) * | 2006-07-27 | 2010-07-21 | 华为技术有限公司 | Method for transmitting, receiving broadcast service and corresponding device and broadcasting system |
| CN1973476B (en) * | 2004-07-30 | 2010-09-01 | 诺基亚公司 | Point-to-point repair request mechanism for point-to-multipoint transmission systems |
| CN101953132A (en) * | 2008-03-28 | 2011-01-19 | 高通股份有限公司 | Method and system for transmit upsampling via IFFT |
| CN101262461B (en) * | 2007-03-09 | 2011-04-20 | 株式会社日立制作所 | OFDM modulator |
| CN102315855A (en) * | 2010-05-06 | 2012-01-11 | 联发科技股份有限公司 | Method according to the mode of operation regulating system clock of non-baseband module |
| CN103560857A (en) * | 2007-08-30 | 2014-02-05 | Lg电子株式会社 | Apparatus for transmitting and receiving a signal and method for transmitting and receiving a signal |
| CN1933390B (en) * | 2005-09-15 | 2014-08-13 | 三星电子株式会社 | Method for generating a frame in an orthogonal frequency division multiple access communication system |
| CN104270332A (en) * | 2005-03-10 | 2015-01-07 | 高通股份有限公司 | Efficient Employment Of Digital Upsampling Using Ifft In Ofdm Systems For Simpler Analog Filtering |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4396423B2 (en) * | 2004-07-05 | 2010-01-13 | パナソニック株式会社 | OFDM receiver |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR970013907A (en) * | 1995-08-25 | 1997-03-29 | 정장호 | High speed data transfer |
| KR20000021965A (en) * | 1998-09-30 | 2000-04-25 | 정선종 | Framer device for radio transmission in atm(asynchronous transfer mode) data |
| KR20000074899A (en) * | 1999-05-27 | 2000-12-15 | 박태진 | Frequency hopping/orthogonal frequency division multiplexing communication system |
| KR20010027280A (en) * | 1999-09-13 | 2001-04-06 | 정선종 | Parallel combinatory processing adaptive communication system and method for supporting multi-transmission rate |
| KR100883942B1 (en) * | 2000-07-12 | 2009-02-18 | 퀄컴 인코포레이티드 | Multiplexing of real time services and non-real time services for ofdm systems |
| CN1332556A (en) * | 2001-04-27 | 2002-01-23 | 清华大学 | Channel transmission method for ground digital multimeldia television broadcast system |
-
2002
- 2002-06-14 KR KR1020020033255A patent/KR20030095709A/en not_active Application Discontinuation
- 2002-09-25 CN CNB021432821A patent/CN1319299C/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1973476B (en) * | 2004-07-30 | 2010-09-01 | 诺基亚公司 | Point-to-point repair request mechanism for point-to-multipoint transmission systems |
| CN104270332A (en) * | 2005-03-10 | 2015-01-07 | 高通股份有限公司 | Efficient Employment Of Digital Upsampling Using Ifft In Ofdm Systems For Simpler Analog Filtering |
| CN1933390B (en) * | 2005-09-15 | 2014-08-13 | 三星电子株式会社 | Method for generating a frame in an orthogonal frequency division multiple access communication system |
| CN101115184B (en) * | 2006-07-27 | 2010-07-21 | 华为技术有限公司 | Method for transmitting, receiving broadcast service and corresponding device and broadcasting system |
| CN101262461B (en) * | 2007-03-09 | 2011-04-20 | 株式会社日立制作所 | OFDM modulator |
| CN103560857A (en) * | 2007-08-30 | 2014-02-05 | Lg电子株式会社 | Apparatus for transmitting and receiving a signal and method for transmitting and receiving a signal |
| CN101953132A (en) * | 2008-03-28 | 2011-01-19 | 高通股份有限公司 | Method and system for transmit upsampling via IFFT |
| US9100254B2 (en) | 2008-03-28 | 2015-08-04 | Qualcomm Incorporated | Method and system for transmit upsampling via IFFT |
| CN102315855A (en) * | 2010-05-06 | 2012-01-11 | 联发科技股份有限公司 | Method according to the mode of operation regulating system clock of non-baseband module |
| CN102315855B (en) * | 2010-05-06 | 2014-03-05 | 联发科技股份有限公司 | Methods for adjusting system clock in terms of operational status of non-baseband module and electronic devices using same |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1319299C (en) | 2007-05-30 |
| KR20030095709A (en) | 2003-12-24 |
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