CN1206856C - Orthogonal frequency-division multiplying transmitter able to increase transmitting efficiency, and its signal processing method - Google Patents
Orthogonal frequency-division multiplying transmitter able to increase transmitting efficiency, and its signal processing method Download PDFInfo
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- CN1206856C CN1206856C CNB021443092A CN02144309A CN1206856C CN 1206856 C CN1206856 C CN 1206856C CN B021443092 A CNB021443092 A CN B021443092A CN 02144309 A CN02144309 A CN 02144309A CN 1206856 C CN1206856 C CN 1206856C
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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
- H04L27/2634—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J13/00—Code division multiplex systems
- H04J13/0007—Code type
- H04J13/004—Orthogonal
- H04J13/0048—Walsh
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
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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
- H04L27/2602—Signal structure
- H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
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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
- H04L27/263—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators modification of IFFT/IDFT modulator for performance improvement
Abstract
An OFDM transmitter includes a FEC unit codes serial input signals; a S/P conversing unit converses encoding signals output from FEC unit; an IDFT unit inverse-discrete-Fourier-transforms a parallel encoding OFDM signal of frequency domain output from the S/P conversing unit into OFDM signal of time domain; a P/S conversing unit converses OFDM signal of parallel time domain output from IDFT into serial OFDM signal; a GI inserting unit inserts a GI into the serial OFDM signal to repress interference between OFDM symbols of serial OFDM signal; a synchronous insertion unit inserts synchronous information used for synchronization of the OFDM signal and channel prediction into the OFDM signal of GI, wherein synchronous information includes PN sequence and sending parameter; a filtering unit for filtering wave inserted OFDM signal of synchronous information; and a RF unit for conversing filtering OFDM code signal into RF signal, then sends the RF signal.
Description
Technical field
The present invention relates to OFDM (OFDM) transmitter, more particularly, relate to the OFDM transmitter that can improve transmitting efficiency.
Background technology
Usually, the broadcast system of HDTV (high definition TV) can roughly be divided into image encoding unit and modulating unit.The digital data compression of the about 1Gbps (Gigabits per second) with high image quality that the image encoding unit will obtain from image source becomes 15 MBPSs to 16 MBPSs.Modulating unit to the limited bandwidth channel of 8MHz, sends to receiver with the numerical data of about tens MBPSs by 6MHz.The high definition broadcasts of digital form has been selected ground broadcast mode simultaneously, and existing VHF (very high frequency(VHF))/UHF (hyperfrequency) channel that broadcasting is used of distributing to has been adopted on ground wherein broadcast mode simultaneously.So, use the modulator approach in the HDTV broadcast system should satisfy following condition.
At first, the modulator approach that is applied to HDTV broadcasting should have high spectrum efficiency, so that transmit the numerical data of about tens MBPSs to the limited bandwidth channel of 8MHz by 6MHz.Secondly, the modulator approach that is applied to the HDTV broadcast system has the multipath fading that causes because of building and structure, and like this, it should be antifading by force.The 3rd, the modulator approach that is applied to the HDTV broadcast system must have the cochannel (co-channel) that causes because of existing anolog TV signals to be disturbed, and like this, it should be that strong anti-cochannel disturbs.In addition, being applied to the modulator approach of HDTV broadcast system should be with the minimum interference of traditional television receiver.
So in Europe, the OFDM method is used as HDTV terrestrial broadcasting method, HDTV terrestrial broadcasting method wherein is a kind of Ditital modulation method, can improve the transfer rate of each bandwidth and can prevent and disturb.
The OFDM method is a kind of such method, can be that the unit will convert parallel data to as the symbol row of serial type input with the predetermined block, and, carry out the operation that parallel symbol is multiplexed into sub-carrier frequencies different from each other.The OFDM method adopts multicarrier, with traditional signal carrier method suitable difference is arranged.Multicarrier has orthogonality between each carrier wave.The quadrature characteristics are meant that when two carrier multiplication, the value that obtains is zero, and this is the requirement to the multicarrier that allows to use.The OFDM method realizes by FFT (fast fourier transform) and IFFT (contrary fast fourier transform), and, by the definition of orthogonality between the carrier wave and FFT, can easily obtain the OFDM method.
On the other hand, the advantage of OFDM method is as described below.In the TV method of terrestrially transmitting, the factor that delivery quality relied on has disturbing and adjacent channel interference such as reflected wave, cochannel of being produced in signal transmits, and like this, specifies the condition of transfer system very difficult.Yet OFDM has strong anti-multi channel characteristics.In other words, owing to used a plurality of carrier waves, the delivery time of symbol just can be expanded.And OFDM is not quite responsive to multi channel interference signal, and like this, even long echo-signal is arranged, efficient can not worsen yet.And OFDM or strong anti-existing signal, so, disturb the relevant considerable degree that do not affect with cochannel.Here, Single Frequency Network is meant and uses single-frequency to carry out single broadcasting in China.So, when the same frequency interference becomes serious, just can adopt the OFDM mode, because it can resist above-mentioned situation by force.When adopting Single Frequency Network, limited frequency just can be used effectively.
Simultaneously, ofdm signal is made up of multicarrier, and each multicarrier has very narrow bandwidth.So the shape of entire spectrum almost is square, like this, its frequency efficiency increases relatively than the frequency efficiency of single carrier.Correspondingly, in the OFDM method, can be different to each carrier modulating method, so transmission can be operated at different layers.
Usually, use the time-division to transmit the OFDM transmitter of ofdm signal synchronously, rearrange the ofdm signal that forms about frequency axis, so that the single service that is assigned with based on the frequency band of time shaft about having set up to be provided.The OFDM transmitter inserts protection (GI) at interval before the ofdm signal that forms along time shaft, in case the interference between the stop signal.In addition, synchronizing information is inserted in before the GI, and is transmitted.
The synchronous insertion unit that is used to insert synchronizing information inserted timing synchronizing signal and the frame synchronization that is used for predicted channel before GI, and correspondingly, as shown in fig. 1, signal frame is made up of frame synchronization and frame section, and frame section wherein is made up of sample (sample) data of GI and predetermined number.
Fig. 1 shows the form of common ofdm signal,, in Fig. 1, shows physical channel frame structure of the present invention that is.Frame structure has layering, and basic frame structure is called as signal frame.The frame group is defined as one group of signal frame, and first frame of frame group is defined as frame group head.Superframe is defined as a cover frame group.The top layer of frame structure is called as the superframe group.As directed, a superframe group comprises 478 superframes, and a superframe comprises 512 frame groups, and a frame group comprises 255 signal frames.Physical channel is periodic, and with absolute time be synchronous.
Signal frame is the elementary cell that is used for downlink physical channel.A signal frame is dimeric, and a part is a frame sync segment, and another part is the frame section.The baseband signalling speed that is used for frame sync segment and frame section is the same, is defined as 7,56MSps.Frame sync segment is with two-phase PSK (BPSK) modulation, so as to obtain stable synchronously.Sync section comprises preamble (preamble) buffering, PN (pseudo noise) sequence and postamble (preamble) buffering.Number of symbols in sync section depends on the number of the symbol in preamble buffering and the postamble buffering, and is as shown in table 1.
Table 1, the number of symbols in sync section.
| Number of symbols in sync section | Number of symbols in the preamble buffering | Number of symbols in the PN sequence | Number of symbols in the postamble buffering |
| 256 | 0 | 255 | 1 |
| 304 | 24 | 255 | 25 |
| 384 | 25 | 255 | 104 |
The frame section is adopted the OFDM modulator approach.Discrete Fourier transform (DFT) (DFT) piece has 3780 symbols and keeps 550 microseconds.Protection is selected as 1/6,1/9,1/12,1/20 or 1/30 of DFT piece at interval, and is as shown in table 2.
Table 2, the number of symbols in an OFDM piece.
| Number of symbols in the OFDM piece | Protection is the ratio in DFT at interval | Number of symbols in protection at interval |
| 4410 | 1/6 | 630 |
| 4200 | 1/9 | 420 |
| 4095 | 1/12 | 315 |
| 3969 | 1/20 | 189 |
| 3906 | 1/30 | 1 26 |
According to selected frame sync segment and OFDM protection interval, a signal frame will have different numbers of symbols, and will be as shown in table 3.Table 3 has also been listed and the corresponding time of signal frame.
Table 3, the number of the symbol in signal frame.
| The time of frame sync segment (microsecond) | The number of the symbol in signal frame | The number of the symbol in frame sync segment | The number of the symbol in the OFDM piece |
| 617.2 | 4666 | 256 | 4410 |
| 623.5 | 4717 | 304 | 4410 |
| 634.1 | 4794 | 384 | 4410 |
| 589.4 | 4456 | 256 | 4200 |
| 595.8 | 4504 | 304 | 4200 |
| 606.3 | 4584 | 384 | 4200 |
| 575.5 | 4351 | 256 | 4095 |
| 581.9 | 4399 | 304 | 4095 |
| 592.5 | 4479 | 384 | 4095 |
| 558.9 | 4225 | 256 | 3969 |
| 565.2 | 4273 | 304 | 3969 |
| 575.8 | 4353 | 384 | 3969 |
| 550.5 | 4162 | 256 | 3906 |
| 556.9 | 4210 | 304 | 3906 |
| 567.5 | 4290 | 384 | 3906 |
A frame group comprises 255 signal frames, and wherein, first signal frame is defined as frame group head.Signal frame in the frame group has unique frame number respectively, and frame number is from 0 to 254.Signal frame number (FN) is encoded into the frame synchronization PN sequence of current demand signal frame.The duration of frame group (duration) depends on the number of sample in its signal frame, and its scope is from 140.4 milliseconds to 161.7 milliseconds.
Superframe is numbered, and to become be from the 0 frame group number to maximum.Hyper Frame Number (SFN) and superframe group number (SFGN) are encoded in the first frame group head of superframe together.
Superframe group number (SFGN) is defined as being used for the data to the transmission of superframe group.The superframe group periodically repeated in a consecutive days, and, be encoded into preceding two bytes of the first frame group head of the superframe in the down link superframe group, its coded format be month, day and year, for example, ten's digit MMDDYY, as shown in table 4.At (PST) 0:0:0 Pacific standard time: in the morning (AM), physical channel frame structure just is reset, and begins a new superframe group.The number of the superframe in each superframe group is approximately 1130 to 1044.When resetting, last superframe of each superframe group may be incomplete.
The symbols sequence number (SSN) that transmits on the down link, the definition that is based on symbols is named.
As mentioned above, the lower layer of the synchronous channel structure of layering is comprised in the frame of down link.SFGN and SFN as the higher layer of the synchronous channel structure of layering are encoded in first frame group head of superframe.SFGN bag and DFN bag are defined as the superframe-synchronized bag, and be as shown in table 4.
Table 4, down link superframe-synchronized bag.
| D3 | D2 | D1 | D0 | M3 | M2 | M1 | M0 |
| Y6 | Y5 | Y4 | Y3 | Y2 | Y1 | Y0 | D4 |
| SFGN7 | SFGN6 | SFGN5 | SFGN4 | SFGN3 | SFGN2 | SFGN1 | SFGN0 |
| SFN7 | SFN6 | SFN5 | SFN4 | SFN3 | SFN2 | SFN1 | SFN0 |
| SFGN8 | SFN8 | FNG8 | BS4 | BS3 | BS2 | BS1 | BS0 |
[M3 ... M0]: month: from 1 to 12
[D4 ... D0]: day: from 1 to 31
[Y6 ... Y0]: year: from 0 to 99
[SFGN8 ... SFGN0]: the superframe group number
[SFN8 ... SFN0]: Hyper Frame Number
[BS4 ... BS0]: the identifier of base station, default value 0.
As shown in fig. 1,255 signal frames form a signal frame group.Frame synchronization has the PN sequence that is increased and the binary data of walsh code.
Here, frame synchronization is to have the PN sequence that is increased and the binary data value of the 16th walsh code, and PN sequence wherein is 255 data values by the block diagram output of Fig. 2 A, shown in walsh code wherein such as Fig. 2 B.
Fig. 2 A is the block diagram that is used to produce traditional linear feedback shift register (LFSR) of common PN sequence.
The base band frame synchronizing signal is made up of preamble buffering, PN sequence and postamble buffering.The preamble buffering can be defined as 0,24 and 25 symbols, and the postamble buffering can be defined as 1,25 and 104 symbols, and the PN sequence has 255 symbols.Unlike signal frame in the signal frame group has different frame synchronizing signals.So in order to discern, frame sync segment can be used as the certain synchronization features that is used for signal frame.Preamble buffering and postamble are defined as the cyclic extensions of PN sequence.
The PN sequence is defined as the m sequence on one 8 rank, and, realize by Fibonacci (Fibonacci) linear feedback shift register (LFSR).Its proper polynomial is x
8+ x
6+ x
5+ x+1.The state of the m sequence that obtains is decided by initial condition module (module).
By numerical value " 0 " is mapped to+1 and " 1 " be mapped to " 1 ", the PN sequence can be converted to the non-return-to-zero binary signal.N rank walsh code can produce by Hadamard (Hadamard) matrix.N rank Hadamard matrix can recursively be set up.
Second order Hadamard matrix H (2) is defined by:
0 0
0 1
Quadravalence Hadamard matrix H (4) is defined by:
0 0 0 0
0 1 0 1
0 0 1 1
0 1 1 0
Because N=2k, N rank Hadamard matrix H (N) are defined by:
H(N)＝H(2)×H(N/2)
N rank walsh code may be defined as a row of N rank Hadamard matrix.The walsh code word is a row of Hadamard matrix.The symbol of walsh code may be defined as the number of times of from 0 to 1 and from 1 to 0 conversion in code word.
Fig. 2 B shows the schematic diagram of the structure of the 16th walsh code, and the symbol of walsh code word is shown in the tabulation on the left side.
In order to realize the identification of a plurality of base stations, frame synchronization sequence is encoded with 16 rank walsh code words.Be used to discern the base station and the step of a PN sequence of walsh codes is as follows:
(1) by the CDTVN network manager, is base station selected one 16 rank walsh code.
(2) according to the preamble buffering/back sync buffering of PN sequence, each of code word " 1 " and each " 0 " are repeated 16/19/24 time, and like this, 16 walsh code is extended to 256/304/384 vector.
(3) with the frame synchronization sequence of coding, carry out XOR (XOR) operation by turn with the vector that in step (2), produces, to set up the frame synchronization sequence of walsh codes.
Correspondingly, 16 of the PN sequence data are coupled with the walsh code of a bit.Here, walsh code is used to discern the base station that sends data, that is, walsh code is the transmission identifier that is used to discern the base station.
Usually, because the influence of base station in a reception area is limited, be difficult to surpass the identification of 8 base stations.So, because 16 traditional rank walsh code are replaced to the walsh code on 8 rank, the zone of using 8 minimum rank walsh code, correct transmission meeting is more efficient, is used for channel and receives desired information to such an extent as to can send.
Summary of the invention
Problem in the prior art that the present invention is mentioned above being devoted to overcome.Correspondingly, the purpose of this invention is to provide a kind of OFDM (OFDM) transmitter, be used for sending the ofdm signal that has the useful information that is inserted into frame synchronization, so that receiver receives better.
By OFDM transmitter according to the present invention, can realize above-mentioned purpose.This OFDM transmitter comprises: forward error correction (FEC) unit is used for the signal encoding with the serial input; Serial (S/P) converting unit is used to change the encoded signals from the output of described FEC unit; Contrary discrete Fourier transform (DFT) (IDFT) unit is used for and will becomes the parallel time domain ofdm signal from the contrary discrete Fourier transform (DFT) of ofdm signal of the parallel encoding of the frequency domain of described S/P converting unit output; Parallel/serial (P/S) converting unit, be used for converting described parallel time domain ofdm signal to serial OFDM signal from the output of described IDFT unit; The unit is inserted in protection (GI) at interval, is used for inserting GI in serial OFDM signal, to be suppressed at the intersymbol interference between the OFDM symbols of serial OFDM signal; Insert the unit synchronously, be used for inserting synchronizing information, be used to insert the synchronous and channel estimating of the ofdm signal of GI at the ofdm signal that has inserted GI; Filter unit is used for the ofdm signal that synchronizing information has been inserted in filtering; And radio frequency (RF) unit, the ofdm signal that has been used for filtering is up-converted into the RF signal, and described RF signal sent, wherein, described synchronizing information comprises pseudo noise sequence and sends parameter, and described synchronous insertion unit comprises XOR gate, is used for described pseudo noise sequence and described transmission parameter are carried out xor operation.
According to the present invention, provide a kind of sending method of the OFDM of being used for transmitter.The method comprising the steps of: (a) signal encoding that serial is imported; (b) conversion of signals that is encoded that will produce in described step (a) becomes the ofdm signal of parallel encoding; (c) the contrary discrete Fourier transform (DFT) of the ofdm signal of the parallel encoding in the frequency-region signal that will produce in step (b) becomes the parallel time domain ofdm signal; (d) the described parallel time domain OFDM signal that will produce in described step (c) converts the ofdm signal of serial to; (e) in serial OFDM signal, insert GI, to be suppressed at the intersymbol interference between the OFDM symbol in the described serial signal; (f) in the ofdm signal that has inserted GI, insert synchronizing information, be used to insert the synchronous and channel estimating of the ofdm signal of GI; (g) ofdm signal of synchronizing information has been inserted in filtering; (h) with filtering ofdm signal be up-converted into the RF signal, and described RF signal sent, wherein, described synchronizing information comprises pseudo noise sequence and sends parameter, and described step (f) comprises the substep (f1) that described pseudo noise sequence and described transmission parameter is carried out xor operation.
And, according to the present invention, provide a kind of signal processing method in the OFDM transmitter.This signal processing method comprises step: the contrary discrete Fourier transform (DFT) of the ofdm signal in the frequency domain is become data in the time domain; To protect at interval (GI) be inserted into contrary discrete Fourier transform (DFT) ofdm signal, to be suppressed at the intersymbol interference between the OFDM symbol in the ofdm signal; With in the ofdm signal that has inserted GI, insert synchronizing information, be used for ofdm signal synchronously and channel estimating, wherein, synchronizing information comprises pseudo noise (PN) sequence and channel information.
Description of drawings
By description of the preferred embodiment of the present invention with reference to the accompanying drawings, objects and advantages of the present invention above-mentioned will be clearer, wherein:
Fig. 1 shows the schematic diagram of the data format of common ofdm signal;
Fig. 2 A is the block diagram that produces common PN sequence;
Fig. 2 B shows the schematic diagram of the structure of 16 rank walsh code;
Fig. 3 is the block diagram that is shown schematically in according to OFDM transmitter of the present invention;
Fig. 4 shows the block diagram of a preferred embodiment of the synchronous insertion unit of Fig. 3;
Fig. 5 shows the block diagram of another preferred embodiment of the synchronous insertion unit of Fig. 3;
Fig. 6 A shows the schematic diagram of the structure of 8 rank walsh code;
Fig. 6 B and Fig. 6 C show the schematic diagram of some data relevant with the sign map pattern with protecting interval mode; With
Fig. 7 shows the signal processing method in the OFDM transmitter of Fig. 3.
Embodiment
Below, will be described in greater detail with reference to the attached drawings according to a preferred embodiment of the invention.
Fig. 3 shows the block diagram according to the preferred embodiment of OFDM transmitter of the present invention.This OFDM transmitter has: FEC (forward error correction) unit 100, serial (S/P) converting unit 200, IDFT (contrary discrete Fourier transform (DFT)) unit 300, parallel/serial (P/S) converting unit, GI (protection at interval) insert unit 500, insert unit 600, filter unit 700 and RF unit 800 synchronously.
The error-detecting method that FEC unit 100 passes through about the foundation of OFDM symbol will be imported the data bit stream encryption, so that proofread and correct the mistake in receiver.
Serial converting unit 200 is carrying out serial data to export parallel data after the error correction coding.
Being converted into serial data from IDFT unit 300 output as N sample data of parallel data parallel/serial conversion unit 400 is output afterwards.
Unit GI to N the sample data relevant with the serial data of output inserts unit 500 insertion GI.It is in order to prevent the interference between the adjoining frame section of signal frame as shown in fig. 1 and that be made up of 255 frame sections that GI is provided.
Next, 700 pairs of ofdm signals of filter unit carry out filtering, and then, in RF unit 800, the ofdm signal of filtering is become RF (radio frequency) signal by upconversion process, and is sent on the channel.
Hereinafter, will the preferred embodiments of the present invention be described with reference to figure 4 and Fig. 5.Insert the information that receiving efficiency requires that improves with describing by lock unit 60.
Fig. 4 shows the preferred embodiment according to the synchronous insertion unit 600 of Fig. 3 of the present invention.Fig. 4 shows the block diagram that synchronizing signal produces, synchronizing signal is to combine with the PN sequence by the blended data with 8 rank walsh code and transmission supplemental characteristic to produce, wherein, the blended data of 8 rank walsh code is the transmission identifiers as the identification base station.
As shown in fig. 1, frame synchronization be inserted into have in IDFT 300 inverse Fourier transform data before inserted the frame section of GI the front.Frame synchronization is synchronizing information, is by XOR gate 619, with 8 rank walsh code shown in PN sequence 611, Fig. 6 A with send that supplemental characteristic 615 produces after mixing by multiplexer (MUX) 617.Sending supplemental characteristic here, is to be used for synchronously and the ISN speed data of channel estimating, to protect at least a of interval mode data and sign map mode data.
For the length of the length (16) of PN sequence being mixed output with MUX 617 is complementary, between MUX 617 and XOR gate 619, be provided with a duplicator (not shown).
On the other hand, Fig. 5 shows the block diagram of another preferred embodiment of the synchronous insertion unit of Fig. 3.Because the information that sends from the base station can be received machine examination usually and measure, synchronizing information is by XOR gate 629, only will send supplemental characteristic 625 and 621 mixing of PN sequence, and not comprise 8 rank walsh code.Sending supplemental characteristic is interior bit rate or GI pattern or the sign map pattern or the combination of interior bit rate, GI pattern and sign map pattern.For example, Fig. 6 B and Fig. 6 C show the schematic diagram based on constellation (constellation) and GI pattern (1/4,1/6,1/9,1/12,1/20 and 1/30) certain code relevant with sign map pattern (QPSK, 16QAM and 64QAM).In Fig. 6 C, two zero bits have been increased on the right side, to isolate GI pattern and sign map pattern.In Fig. 6 B, 8 Bit datas are selected code, in case the relation between the minimise data, and in Fig. 6 C, 6 Bit datas also can be selected code, with the correlation between the minimise data.
When use had the synchronous insertion unit of structure of Fig. 5, the length that sends supplemental characteristic was 16 bits.Correspondingly, a corresponding signal frame in easier difference and 15 patterns just.So, just can omit the global positioning system that is used for transmitting system (GPS) that often is used.
So, when desired information is added to the PN sequence, in receiver, just can easily retrieve the needed information of channel, so, just can improve receiving efficiency.
Fig. 7 has described a kind of method of treatment in accordance with the present invention signal, is used for the transmitter at OFDM, and the channel information data are inserted in the PN sequence.
In FEC 100 error correction coding serial data in serial converting unit 200, be output, with as parallel data (step S10).
In IDFT 300, the parallel data of having changed are become sample data (step S20) in the time domain by inverse Fourier transform.Then, the inverse Fourier transform in the time domain sample data, in parallel/serial conversion unit 400, be transformed into and be output (step S30) after the serial data.
It is that unit inserts GI (step S40) in the serial data of output with the frame section that GI inserts unit 500.When ofdm signal has been inserted into GI in GI insertion unit 500 after, insert unit 600 synchronously synchronizing information is inserted in the ofdm signal that has inserted GI, be used for the synchronous and channel estimating (step S50) of receiver side.
Synchronizing information can be PN sequence, eight rank walsh code 613 and the binding data that sends supplemental characteristic 615, as shown in Figure 4, maybe can be PN sequence 621 and the binding data that sends supplemental characteristic 625.In the channel information data can become bit rate or on receiver, be used to receive ofdm signal synchronously and the GI pattern of channel estimating, or, maybe can be the combination of interior bit rate, GI pattern and sign map pattern according to the sign map pattern of constellation.
Next, OFDM filtered unit 700 filtering then, are sent to wireless channel (step S60) by RF unit 800.
As mentioned above, combine with the PN sequence by comprising at least one the transmission parameter in interior bit rate, GI and the sign map pattern, come as frame synchronization, that is, synchronizing information can improve the receiving efficiency of receiver.
According to the present invention, in digit broadcasting system, the PN sequence is inserted into and increases the necessary information that is used for receiving terminal.Because receiver can easily retrieve the necessary information that is used for channel, receiving efficiency just can improve a lot.
Although described the preferred embodiments of the present invention, those skilled in the art should be appreciated that the present invention is not limited to described preferred embodiment, within the spirit and scope of the invention, variations and modifications can be arranged.Correspondingly, scope of the present invention is not limited to described scope, but is limited to appended claim.
Claims (13)
1. an orthogonal frequency division multiplex ransmitting send device, comprising:
Forward error correction unit is used for the signal encoding with the serial input;
The serial converting unit is used to change the encoded signals from described forward error correction unit output;
Contrary discrete Fourier transform unit is used for and will becomes the parallel time domain orthogonal frequency-division multiplex singal from the contrary discrete Fourier transform (DFT) of orthogonal frequency-division multiplex singal of the parallel encoding of the frequency domain of described serial converting unit output;
Parallel/the serial conversion unit, be used for converting described parallel time domain orthogonal frequency-division multiplex singal to serial time domain orthogonal frequency-division multiplex singal from described contrary discrete Fourier transform unit output;
Protection is inserted the unit at interval, is used for inserting protection at interval at serial time domain orthogonal frequency-division multiplex singal, to be suppressed at the intersymbol interference between the OFDM symbol in the serial time domain orthogonal frequency-division multiplex singal;
The insertion unit is used for inserting synchronizing information at the orthogonal frequency-division multiplex singal that has inserted the protection interval synchronously, has been used to insert the synchronous and channel estimating of protection orthogonal frequency-division multiplex singal at interval;
Filter unit is used for the orthogonal frequency-division multiplex singal that synchronizing information has been inserted in filtering; With
Radio frequency unit, the orthogonal frequency-division multiplex singal that has been used for filtering is up-converted into radiofrequency signal, and described radiofrequency signal sent,
It is characterized in that described synchronizing information comprises pseudo noise sequence and send parameter, and described synchronous insertion unit comprises XOR gate, be used for described pseudo noise sequence and described transmission parameter are carried out xor operation.
2. orthogonal frequency division multiplex ransmitting as claimed in claim 1 send device, and wherein, described synchronous insertion unit comprises:
Multiplexer is used to mix sender identification symbol and described transmission parameter, to produce the information of combination; With
Described XOR gate is used for the combined information and the described pseudo noise sequence that produce from described multiplexer are carried out xor operation.
3. orthogonal frequency division multiplex ransmitting as claimed in claim 2 send device, wherein, described synchronous insertion unit also comprises a duplicator, be used to repeat the bit of described combined information, so that the length of the length of described combined information and described pseudo noise sequence is complementary be used for described combined information is exported to described XOR gate.
4. orthogonal frequency division multiplex ransmitting as claimed in claim 2 send device, and wherein, described transmitter identifier is the walsh code that is used for identification of base stations.
5. the orthogonal frequency division multiplex ransmitting as any one claim in the claim 1 to 4 send device, and wherein, described transmission parameter comprises at least one in protection interval mode, interior bit rate and the sign map pattern.
6. orthogonal frequency division multiplex ransmitting as claimed in claim 5 send device, and wherein, the protection interval mode comprises in 1/4,1/6,1/9,1/12,1/20 and 1/30 pattern.
7. orthogonal frequency division multiplex ransmitting as claimed in claim 5 send device, and wherein, the sign map pattern comprises in two-phase PSK pattern, 16 quadrature amplitude modulation patterns and the 64 quadrature amplitude modulation patterns.
8. one kind is used for the sending method that orthogonal frequency division multiplex ransmitting send device, and the method comprising the steps of:
(a) signal encoding that serial is imported;
(b) conversion of signals that is encoded that will produce in described step (a) becomes the orthogonal frequency-division multiplex singal of parallel encoding;
(c) the contrary discrete Fourier transform (DFT) of the orthogonal frequency-division multiplex singal of the parallel encoding in the frequency-region signal that will produce in step (b) becomes the parallel time domain orthogonal frequency-division multiplex singal;
(d) the described parallel time domain orthogonal frequency-division multiplex singal that will produce in described step (c) converts the time domain orthogonal frequency-division multiplex singal of serial to;
(e) in serial time domain orthogonal frequency-division multiplex singal, insert protection at interval, to be suppressed at the intersymbol interference between the OFDM symbol in the described serial time domain orthogonal frequency-division multiplex singal;
(f) in having inserted protection orthogonal frequency-division multiplex singal at interval, insert synchronizing information, be used to insert the synchronous and channel estimating of protection orthogonal frequency-division multiplex singal at interval;
(g) orthogonal frequency-division multiplex singal of synchronizing information has been inserted in filtering; With
(h) with filtering orthogonal frequency-division multiplex singal be up-converted into radiofrequency signal, and described radiofrequency signal is sent,
It is characterized in that described synchronizing information comprises pseudo noise sequence and send parameter, and described step (f) comprises the substep (f1) that described pseudo noise sequence and described transmission parameter is carried out xor operation.
9. as claimed in claim 8ly be used for the sending method that orthogonal frequency division multiplex ransmitting send device, wherein, described step (f) also comprises substep:
(f2) sender identification is accorded with and sends parameter combinations to produce combined information; With
(f3) combined information and the described pseudo noise sequence that will produce in step (f2) is carried out xor operation.
10. as claimed in claim 9ly be used for the sending method that orthogonal frequency division multiplex ransmitting send device, wherein, described sender identification symbol is the walsh code that is used for identification of base stations.
11. as the sending method that orthogonal frequency division multiplex ransmitting send device that is used for of any one claim in the claim 8 to 10, wherein, described transmission parameter comprises at least one in protection interval mode, interior bit rate and the sign map pattern.
12. as the sending method that orthogonal frequency division multiplex ransmitting send device that is used for of claim 11, wherein, the protection interval mode comprises in 1/4,1/6,1/9,1/12,1/20 and 1/30 pattern.
13. as the sending method that orthogonal frequency division multiplex ransmitting send device that is used for of claim 11, wherein, the sign map pattern comprises in two-phase PSK pattern, 16 quadrature amplitude modulation patterns and the 64 quadrature amplitude modulation patterns.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR30395/2002 | 2002-05-30 | ||
| KR1020020030395A KR100864709B1 (en) | 2002-05-30 | 2002-05-30 | OFDM Transmitter capable of improving the quality of receiving and a method processing OFDM signal thereof |
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| Publication Number | Publication Date |
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| CN1463146A CN1463146A (en) | 2003-12-24 |
| CN1206856C true CN1206856C (en) | 2005-06-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB021443092A Expired - Fee Related CN1206856C (en) | 2002-05-30 | 2002-10-09 | Orthogonal frequency-division multiplying transmitter able to increase transmitting efficiency, and its signal processing method |
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| KR (1) | KR100864709B1 (en) |
| CN (1) | CN1206856C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101889273B (en) * | 2007-12-10 | 2013-03-27 | 佳能株式会社 | Signal transmission system and signal conversion circuit |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100927142B1 (en) * | 2002-10-07 | 2009-11-18 | 삼성전자주식회사 | Multicarrier transmission system and its method for improving transmission efficiency |
| KR100945340B1 (en) * | 2003-12-31 | 2010-03-08 | 엘지노텔 주식회사 | A data interface synchronization method for base station system operating multiple standard |
| TWI587649B (en) * | 2005-03-24 | 2017-06-11 | 英特爾股份有限公司 | Transmitting device, receiving device, and method applicable in an orthogonal frequency division multiplexing-code division multiple access system |
| CN1885844B (en) * | 2005-06-20 | 2011-09-07 | 中国科学院上海微系统与信息技术研究所 | Device for reducing peak-to-average ratio based on orthogonal multiplex multi-carrier transmission and its method |
| CN1925474B (en) * | 2005-08-29 | 2010-11-10 | 中国科学院上海微系统与信息技术研究所 | Single carrier frequency-division multi-address transmitting, receiving device based on multiple subband wave filter set and method thereof |
| CN101064707B (en) * | 2006-04-28 | 2010-05-12 | 北京泰美世纪科技有限公司 | Bandlimited stochastic sequence generating method and its apparatus |
| CN101127748A (en) * | 2006-08-15 | 2008-02-20 | 大唐移动通信设备有限公司 | Transmission method and device for uplink synchronization command word in OFDM mobile communication system |
| CN101312360B (en) * | 2007-05-25 | 2012-08-29 | 华为技术有限公司 | Filtering method and apparatus thereof, and crosstalk counteracting method and system thereof |
| KR100977096B1 (en) * | 2008-05-26 | 2010-08-23 | 광운대학교 산학협력단 | Method and apparatus on frame synchronization for OFDM system |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5751774A (en) * | 1996-04-04 | 1998-05-12 | Lucent Technologies Inc. | Transmission system for digital audio broadcasting |
| JP2000244441A (en) * | 1998-12-22 | 2000-09-08 | Matsushita Electric Ind Co Ltd | Ofdm transmitter-receiver |
| KR20000074899A (en) * | 1999-05-27 | 2000-12-15 | 박태진 | Frequency hopping/orthogonal frequency division multiplexing communication system |
| KR100342520B1 (en) * | 2000-08-18 | 2002-06-28 | 윤종용 | Method and apparatus for masking cyclic prefix in mobile communication system |
-
2002
- 2002-05-30 KR KR1020020030395A patent/KR100864709B1/en active IP Right Grant
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101889273B (en) * | 2007-12-10 | 2013-03-27 | 佳能株式会社 | Signal transmission system and signal conversion circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20030092660A (en) | 2003-12-06 |
| KR100864709B1 (en) | 2008-10-23 |
| CN1463146A (en) | 2003-12-24 |
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