CN101119353A - Ldpc coding based tds-ofdm communication system transmitter - Google Patents
Ldpc coding based tds-ofdm communication system transmitter Download PDFInfo
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Abstract
An OFDM (Orthogonal frequency-division multiplexing) communication system is provided. The system includes at least two programs being simultaneously transmitted under one spectrum. Each program is respectively modulated under a different or similar scheme. Each of the at least two programs commonly share a control frame. The control frame is transmitted under a similar or more robust modulation scheme than the at least two programs' modulations respectively.
Description
Related application is quoted
The application advocates to be disclosed in the right that on July 25th, 2006, provisional application number are 60/820,316 United States Patent (USP), and the full content that relates to this application is integrated with the application by reference.
Technical field
The invention belongs to communication technical field, specifically, relate to based on low-density checksum (LDPC, Low-density Parity Check) Bian Ma time-domain synchronization OFDM (TDS-OFDM, Time Domain Synchronous-Orthogonal FrequencyDivision Multiplexing) communication system transmitter.
Background technology
The internet signal transmission is different from the digital television signal transmission, but all is faced with the various challenges of continuous proposition.The problem that the transmitting internet signal is faced is the reliable broadcast and the multicast of message, for transmitter and reception provide mobility, and the restriction of the rate of information throughput (" speed ").The problem that transmitting digital TV signal faced provides interactive system, and the message transmission capability of point-to-point is provided, and moves reception.The digital television signal transmission system is efficiently from certain meaning, because central payload of the frame of each transmission or data division account for very big ratio in the entire frame the inside.Simultaneously, the variation characteristic of transmission channel should be able to be confirmed and compensate to such communication system, includes but not limited to the time-delay of each frame when transmission.
OFDM (OFDM, Orthogonal frequency-divisionmultiplexing) modulation system is a technique known.OFDM, be also sometimes referred to as Discrete multi-tone modulation (DMT, Discrete Multitone Modulation), be a kind of based on frequency division multiplexing (FDM, Frequency-Division Multiplexing) the complex modulation technology transmitted of thought, each frequency channel is used better simply modulation system.In OFDM, the frequency of FDM and modulation are quadrature each other, so just can eliminate the interference of interchannel substantially.Conventional OFDM transmission need have a protection at interval between the OFDM Frame, isolate the OFDM frame that is sent, and realizes protection.More precisely, protection is that the circulation of OFDM data repeats at interval, and it has been represented to preventing that data are subjected to disturbing between the subcarrier of frequency domain and the inter-frame-interference of time domain, required time period between the OFDM Frame.
Authorize people such as Yang Lin, U.S. Patent number is that 7,072,289 patent has been described a kind of Domain Synchronous OFDM (TDS-OFDM, Time-Domain Synchronous OFDM) modulation system.In the TDS-OFDM modulation, (PN, Pseudo-Noise) sequence realize synchronous and channel estimating etc. to insert pseudorandom in the protection between the Frame at interval.TDS-OFDM modulation and conventional OFDM or coded OFDM are modulated different; because the TDS-OFDM modulation system does not adopt the circulation of OFDM data to repeat in protection at interval; and be to use a PN sequence; receiver is under the situation of extraneoas loss spectrum efficiency not like this; can realize synchronous faster; frame and regularly recovery faster, and more the channel estimating of robust is recovered information transmitted.In an application, the TDS-OFDM modulation scheme is used the 3780 point fast Fourier conversion (FFT, FastFourier Transform) of 3780 symbolic representation regular lengths.This fixing FFT length is distinctive for the TDS-OFDM modulation system.Conventional OFDM modulation uses 2
nThe FFT of integral multiple length, therefore, do not fix.
In communication channel, error correction commonly used and channel coding schemes reduce error of transmission.Low-density checksum (LDPC, Low-density Parity Check) sign indicating number is a kind of error correcting code that is used in noisy communication channel transmission information and carries out forward error correction (FEC, Forward Error Correction).The LDPC sign indicating number can be regarded a kind of coding with binary parity check matrix as, and the element of parity matrix nearly all is 0.Although LDPC coding and other error correction codings can not guarantee errorless transmission, the probability of loss of information can drop to required degree.The LDPC coding is first kind can make message transmission rate near theoretical maximum, i.e. the encoding scheme of shannon limit.When just finding, the LDPC coding is considered in most of the cases because the amount of calculation of algorithm and encoder is excessive can't practical application, thereby is not used widely.Yet, after the LDPC sign indicating number is rediscovered, in communication system, be used widely.
Summary of the invention
According to an aspect of the present invention, a kind of TDS-OFDM transmitter based on the LDPC coding comprises: a receiving moving pictures expert group standard-2 (MPEG-2) transmits stream and the encoder of encoded data stream is provided, and this encoder comprises that one is adopted the LDPC sign indicating number that MPEG-2 is transmitted the LDPC encoder that stream is encoded; And time-domain synchronization OFDM (TDS-OFDM) modulator that receives the LDPC encoded data stream and produce the digital baseband output signal, modulator adopts the TDS-OFDM modulation scheme.Digital baseband signal comprises a plurality of signal frames, and each signal frame comprises the protection interval of a pseudorandom (PN) sequence as signal frame.
According to another aspect of the present invention, generation and transmission comprise based on the method for the TDS-OFDM modulation signal of LDPC: receive MPEG-2 and transmit stream as input traffic, with pseudorandom (PN) sequence with the input traffic randomization, the later data flow of randomization is carried out the sign indicating number (BCH of BCH Bose-Chadhuri-Hocquengham, Bose, Chaudhuri﹠amp; HocquenghemType of Code) coding; the later data flow of Bose-Chaudhuri-Hocquenghem Code is carried out the LDPC coding; the later data flow of LDPC coding is carried out the TDS-OFDM modulation; produce digital baseband signal; digital baseband signal comprises a plurality of signal frames, and each signal frame comprises the protection interval of a pseudorandom (PN) sequence as signal frame.
Description of drawings
Following specific descriptions and accompanying drawing help better to understand the present invention.
Fig. 1 is the block diagram based on the TDS-OFDM transmitter of LDPC that meets one embodiment of the invention;
Fig. 2 has described the frame structure schematic diagram of TDS-OFDM signal frame;
Fig. 3 has described the schematic diagram based on the TDS-OFDM transmitter function module of LDPC that meets one embodiment of the invention;
Fig. 4 has described the flow chart of data processing figure based on the TDS-OFDM transmitter input signal of LDPC that meets one embodiment of the invention;
Fig. 5 is the concrete flow chart of data processing figure of a kind of LDPC sign indicating number of the present invention, meets the corresponding separately embodiment of the invention;
Fig. 6 is the concrete flow chart of data processing figure of a kind of LDPC sign indicating number of the present invention, meets the corresponding separately embodiment of the invention;
The concrete flow chart of data processing figure of a kind of LDPC sign indicating number of Fig. 7 the present invention meets the corresponding separately embodiment of the invention;
Fig. 8 (a) has described the frame structure schematic diagram of the signal frame that has PN420;
Fig. 8 (b) has described the frame structure schematic diagram of the signal frame that has PN595;
Fig. 8 (c) has described the frame structure schematic diagram of the signal frame that has PN945.
Embodiment
According to principle of the present invention, in the TDS-OFDM communication system based on LDPC, the TDS-OFDM transmitter based on LDPC that is adopted comprises a LDPC encoder and a TDS-OFDM modulator.TDS-OFDM transmitter based on LDPC receives multiplexing MPEG-2 transmission stream as input signal, carries out LDPC coding and TDS-OFDM modulation, produces the output signal on digital I road and digital Q road.Transmitter adopts the forward error correction based on LDPC to realize the performance that communication system is good.The output signal on numeral I road and digital Q road can directly feed back to the methods of digital predistortion device of digital transmitter, transmits on communication channel then.Transmitter can be operated on single-frequency or the multi-frequency network.
TDS-OFDM communication system based on LDPC has many advantages with respect to legacy system, especially strengthens receptivity in digital television broadcasting system.Unified outstanding characteristic of the TDS-OFDM communication system based on LDPC that the present invention proposes is in each signal frame, and the number of MPEG-2 transmission stream packets is a predetermined integer (for example, 2,3,4,6,8,9,12) normally.In the OFDM of routine modulating system, each signal frame all has the packet that ascertains the number under all situations, and this generally is impossible.
In the present invention, the United States Patent (USP) 7 that the TDS-OFDM communication system has referred to use preamble to mention, 072,289 (name is called " adopt pseudo random sequence fill " in the OFDM modulating system, license to people such as Yang Lin, this patent integral body is integrated with this patent by reference) described in the communication system of TDS-OFDM modulation system.In the TDS-OFDM modulation, one is satisfied pseudorandom (PN) sequence of selecting orthogonality and closed relationship and is added in the protection interval of data block.The PN sequence is used for regularly recovery, carrier frequency recovery, channel estimating and synchronous.The PN sequence makes that the receiver of TDS-OFDM communication system can reach faster synchronously, frame and regularly recovering faster, and the channel estimating of robust more.
In this description, also used forward error correction based on LDPC, adopted one group of three LDPC sign indicating number, their characteristic is consistent with the application of TDS-OFDM communication system, and has special advantage.Especially, the TDS-OFDM transmission plan consistent with the present invention uses 3780 symbols, and the parameter of LDPC sign indicating number also is transferred to 3780 symbols consistent with the TDS-OFDM transmission plan.In TDS-OFDM communication system of the present invention, use forward error correction based on LDPC that super error correction performance near the channel shannon limit is provided.In one embodiment, TDS-OFDM transmitter based on LDPC of the present invention has used 3 quasi-cyclic LDPC codes, the description of these yards was proposed by Chen Lei referring on March 13rd, 2007, application number is 11/685,539, name is called the U.S. Patent application of " based on the many speed LDPC sign indicating number in the TDS-OFDM communication system of LDPC ", this patent application integral body is integrated with this patent by reference, as a reference.In this patent application 11/685,539,0.4,0.6,0.8 quasi-cyclic LDPC code and their corresponding parity-check matrix three kinds of code checks have been described are.When three kinds of LDPC sign indicating numbers in this patent application 11/685,539 be used in that the present invention mentions based on the TDS-OFDM transmitter of LDPC the time, that communication system can reach is superpower, near the error-correcting performance of channel shannon limit.
Fig. 1 is the block diagram based on the TDS-OFDM transmitter of LDPC that meets one embodiment of the invention.Referring to Fig. 1, a TDS-OFDM transmitter 20 based on LDPC, it receives MPEG-2 and transmits stream as input signal, produces a digital I and digital Q signal as output signal.In the present embodiment, the input signal of passing to transmitter 20 is assumed to and goes the parallel MPEG-2 that shakes to transmit stream fully.Any serial-to-parallel conversion (digital video broadcasting-Asynchronous Serial Interface (DVB-ASI for example, Digital VideoBroadcasting-Asynchronous Serial Interface) conversion) or program clock reference (PCR, Program Clock Reference) proofread and correct and all to suppose in transmitter 20 outsides and handle.As shown in Figure 1, the DVB-ASI input signal is passed to DVB-ASI to parallel module 10, carries out DVB-ASI to parallel conversion, and then passes to MPEG PCR correction module 12 and carry out the correction of MPEG PCR.Handle later MPEG-2 through these and transmit the TDS-OFDM transmitter 20 conduct inputs of spreading to based on LDPC.
In one embodiment, realize as monolithic integrated circuit based on the TDS-OFDM transmitter 20 of LDPC.DVB-ASI realizes beyond the integrated circuit of transmitter 20 to parallel modular converter 10 and MPEG PCR correction module 12.In other embodiments, the TDS-OFDM transmitter based on LDPC can be combined on the same integrated circuit with conversion, correcting circuit.The integrated level of transmitter 20 is not a key factor to realization of the present invention.
In the TDS-OFDM transmitter 20 based on LDPC, MPEG-2 transmits and spreads to coder module 22, produces coded data stream.Coder module 22 is used a LDPC encoder and input signal is carried out quasi-cyclic LDPC is encoded forward error correction is provided.The later data flow of encoding is passed to TDS-OFDM modulator block 24, and this module adopts the TDS-OFDM modulation scheme to produce the output signal of digital I and digital Q.
Digital output signal based on the TDS-OFDM transmission plan of LDPC is combined into a series of Hierarchichal frame structure.Fig. 2 has shown the frame structure of TDS-OFDM signal frame.Referring to Fig. 2, a TDS-OFDM signal frame comprises the Frame of 3780 symbols, and a protection prefix, variable-length at interval.Frame comprises 3744 symbols of carrying data load and carries 36 symbols of transmission parameter signaling (TPS, Transmission Parameter Signaling).The TPS symbols carry can make demodulator or receiver be fitted to the information of input transmission mode, for example FEC ISN code check and time domain interleaver sizes automatically.
In one embodiment, protection length at interval can be frame length (3780 symbols) divided by 9 (420 symbols), shown in Fig. 8 (a), also can be that frame length is divided by 4 (945 symbols), shown in Fig. 8 (c).Protection length at interval also can be 595 symbols, shown in Fig. 8 (b).
Describe now the formation of the TDS-OFDM transmitter based on LDPC of the present invention in detail.Fig. 3 is the schematic diagram based on the functional module of the TDS-OFDM transmitter of LDPC that meets the embodiment of the invention.Referring to Fig. 3, comprise a coder module 222 and a TDS-OFDM modulator 224 based on the TDS-OFDM transmitter 200 (being called " transmitter 200 " later on) of LDPC.Transmitter 200 reception MPEG-2 transmission streams (TS, Transport Stream) and clock signal produce corresponding digital I and the digital Q output signal of getting as input signal.
The coder module 222 of transmitter 200 comprises 232, one Bose-Chaudhuri-Hocquenghem Code devices 234 of a randomization module and a LDPC encoder 236.Randomization module pseudorandoms of 232 usefulness (PN) sequence is with the input traffic randomization.Randomization was finished before BCH and forward error correction.In receiver/demodulator, recover the PN sequence, and the randomized payload user data that is used to decode.
In one embodiment, the PN sequence that randomization module 232 adopts is that 32767 symbols are long.Further, in a facility example, the PN sequence is by multinomial 1+x
14+ x
15Produce, initial condition is 100101010000000.Randomization module 232 all is reset to initial condition at each signal frame.Other situation it with free-running operation until resetting once more.
The Bose-Chaudhuri-Hocquenghem Code device 234 as outer code coder is coupled in the output of randomization module 232.In the present embodiment, the Bose-Chaudhuri-Hocquenghem Code device adopts BCH (762,752) sign indicating number, is that the binary system of BCH (1023,1013) sign indicating number shortens sign indicating number, and generator polynomial is 1+x
3+ x
10
After data flow was by Bose-Chaudhuri-Hocquenghem Code, signal was sent to the LDPC encoder 236 as ISN FEC encoder.LDPC encoder 236 is weaved into quasi-circulating low-density parity check (QC-LDPC, Quasi-cyclic Low Density Parity Check) sign indicating number to signal.In the present embodiment, the LDPC encoder is the LDPC sign indicating number (code check 0.4, code check 0.6, code check 0.8) of three kinds of different rates.Further, in the present embodiment, three kinds of LDPC sign indicating numbers offer LDPC encoder 236 by LDPC sign indicating number module 238.In other embodiments, the LDPC sign indicating number can offer LDPC encoder 236 by firmware or software.In one embodiment, being described in of three LDPC sign indicating numbers is that on March 13rd, 2007 was proposed by Chen Lei, name is called in the U.S. Patent application of " based on the many speed LDPC sign indicating number in the TDS-OFDM communication system of LDPC ", and application number is 11/685,539.
In the coder module 222 of transmitter 200, information via Bose-Chaudhuri-Hocquenghem Code device 234LDPC encoder 236 waiting for transmission is handled.The Bose-Chaudhuri-Hocquenghem Code device 234 of design and LDPC encoder 236 produce accurate 3780 symbols (3744 the symbol that LDPC generates and the TPS pilot tone of 36 walsh codes), make with 3780 the contrary fast fourier transform (IFFT, Inverse FFT) of modulator block 224 consistent.
Input traffic is given TDS-OFDM modulator 224 through after randomization and encoding.TDS-OFDM modulator 224 comprises 242, one contrary FFT (IFFT of 240, one time domain interleavers of a rate converter; Inverse FFT) module 246; a protection interval insert module 248, and root side's raised cosine (SRRC, Square Root RaisedCosine) filter 250.
In the present embodiment, the TDS-OFDM modulating system is based on different modulation systems (quadriphase PSK (QPSK, Quad Phase Shift Keying), 16 quadrature amplitude modulation (QAM, Quadrature Amplitude Modulation), 64QAM) with different encoder bit rates (0.4,0.6,0.8) multirate system.In this description, QPSK represents quarternary phase-shift keying (QPSK) (QuadPhase Shift Keying), and QAM represents quadrature amplitude modulation (Quadrature AmplitudeModulation).The output signal of outer sign indicating number BCH and ISN LDPC is by bit.According to different modulation systems and code rate, rate converter 240 is merged into byte with the bit output of coder module 222, and adjusts the speed of byte output clock, makes the MPEG-2 bag output signal of modulator evenly to distribute in whole modulated process.
After the rate conversion, signal is coupled to time domain interleaver 242.In TDS-OFDM modulator 224, time domain interleaver 242 is used for strengthening the resistivity that transmits to interference noise.Time domain interleaver 242 is convolutional deinterleaver, needs the memory 244 that size is B* (B-1) * M/2, and wherein B is the quantity of branch, and M is the degree of depth.
After the time domain interleaving block, signal is passed to contrary FFT (IFFT) module 246 of carrying out 3780 inverse Fourier transform operations.In the present embodiment, TDS-OFDM modulator 224 both can be operated under the multi-carrier mode, can be operated under the single carrier mode again.Under multi-carrier mode, shine upon later symbol and be considered to frequency domain data.Therefore, when being elected to the majority carrier mode, signal passes to IFFT module 246, and the IFFT operation becomes corresponding time-domain signal with symbol transition.On the other hand, under single carrier mode, shine upon later symbol and directly just think time domain data.Therefore, when selecting single carrier mode, the IFFT operation will be skipped.
Next step, protection insert module is at interval inserted selected protection at interval, and PN420 or PN595 or PN945 are shown in Fig. 8 (a)-(c).Last signal frame is passed to root side's raised cosine (SRRC, Square Root Raised Cosine) filter 250.After the filtering, modulating data is with digital I and the output of digital Q signal.
Referring to the flow chart of Fig. 4, process is described below based on the data flow of the TDS-OFDM transmitter 200 of LDPC.Referring to Fig. 4, start from receiving MPEG-2 based on the TDS-OFDM modulation system 300 of LDPC and transmit stream as input (step 302).MPEG-2 transmits stream and at first carries out randomization, transmits at frequency domain without any frequency spectrum spike (step 304) guaranteeing.Transmit stream then and deliver to the outer sign indicating number Bose-Chaudhuri-Hocquenghem Code device (step 308) that adopts certain particular B CH code word.The Bose-Chaudhuri-Hocquenghem Code device adds 10 check bits, and 752 bits are weaved into 762 bits.The output signal of Bose-Chaudhuri-Hocquenghem Code device is sent to and is carried out LDPC coding (step 310).The LDPC coding uses one of three kinds of LDPC code words 312 of different code checks.The LDPC coding converts the data flow of several 762 bits to according to operating rate the data block of 7493 bit sizes.5 of the erasure signal piece check bits produce 7488 bits (step 314) then.
Then 7488 bits of LDPC encoder output are sent to and are carried out TDS-OFDM modulation (step 316).At first, 7488 bits carry out rate transition (step 318) through rate converter.Rate converter becomes 3780 symbols (3744 symbols that LDPC produces and the TPS pilot tone of 36 walsh codes) compatible with IFFT length 7488 bits switch.Then, the time domain interleaving block carries out the convolution expansion, and this does not change the size of data block, and just changes the order (step 320) of 3780 symbols.When being elected to the majority carrier mode, 3780 symbols are sent to and are done 3780 contrary FFT conversion (IFFT).IFFT is converted to time-domain signal (step 322) with frequency domain information.If what select is single carrier mode, the IFFT operation is just skipped.Then insert protection (step 324) at interval.The protection of PN420, PN595 or PN945 is distinguished corresponding 420 symbols, 595 symbols or 945 symbols at interval, is inserted in the beginning of the frame of each 3780 symbol.Then output is delivered to the SRRC filter and is carried out frequency spectrum shaping (step 326) and obtain digital I and Q signal (step 328).Digital output signal also can pass through up conversion, and exports as digital intermediate frequency (IF, Intermediate Frequency).
Fig. 5 to Fig. 7 is the flow chart that the designed difference based on the TDS-OFDM transmitter of LDPC of three kinds of different LDPC sign indicating numbers realizes according to the present invention.Referring to flow chart shown in Figure 5 400, when selecting LDPC (7493, the 3048) code word of code check 0.4 (step 408), randomizer provides 752 input signal bits, and they are expressed as 3008 symbols (752 * 4) (step 402).752 bits are weaved into 762 bits (step 404) in the Bose-Chaudhuri-Hocquenghem Code device, produce 3048 symbols (762 * 4).The LDPC encoder is weaved into 7493 bits (step 406) with signal then.Delete 5 check bits and obtain 7488 bits (step 410).Then 7488 bits are modulated (step 412) according to the TDS-OFDM modulation system, produce 3780 symbols (step 414) of each digital I and digital Q output signal.
Referring to flow chart shown in Figure 6 500, when selecting LDPC (7493, the 4572) code word of code check 0.6 (step 508), randomizer provides 752 input signal bits, and they are expressed as 4512 symbols (752 * 6) (step 502).752 bits are weaved into 762 bits (step 504) in the Bose-Chaudhuri-Hocquenghem Code device, produce 4572 symbols (762 * 6).The LDPC encoder is weaved into 7493 bits (step 506) with signal then.Delete 5 check bits and obtain 7488 bits (step 510).Then 7488 bits are modulated (step 512) according to the TDS-OFDM modulation system, produce 3780 symbols (step 514) of each digital I and digital Q output signal.
Referring to flow chart shown in Figure 7 600, when selecting LDPC (7493, the 6096) code words (step 608) of code check 0.8, randomizer provides 752 input signal bits, and they are expressed as 6016 symbols (752 * 8) (step 602).752 bits are weaved into 762 bits (step 604) in the Bose-Chaudhuri-Hocquenghem Code device, produce 6096 symbols (762 * 8).The LDPC encoder is weaved into 7493 bits (step 606) with signal then.Delete 5 check bits and obtain 7488 bits (step 610).Then 7488 bits are modulated (step 612) according to the TDS-OFDM modulation system, produce 3780 symbols (step 614) of each digital I and digital Q output signal.
In conjunction with the accompanying drawings specific embodiments of the invention are had been described in detail above, but the present invention is not restricted to the foregoing description.Not breaking away under the spirit and scope situation of claim of the present invention, can make various modifications or change.Additional claim has defined the present invention.
Claims (19)
1. the TDS-OFDM transmitter based on LDPC is characterized in that, by forming with the lower part:
An encoder receives MPEG-2 transmission stream and provides encoded data stream, encoder to comprise and uses low density parity check code, and promptly the LDPC sign indicating number transmits the LDPC encoder that stream is encoded to MPEG-2; And
A time-domain synchronization OFDM; be the TDS-OFDM modulator, receive the LDPC encoded data stream, and produce the output signal of digital baseband with the TDS-OFDM modulation system; digital baseband signal is made up of signal frame, and each signal frame comprises one as protection PN sequence at interval.
2. the TDS-OFDM transmitter based on LDPC as claimed in claim 1 is characterized in that described encoder comprises:
A randomizer receives MPEG-2 and transmits stream as input traffic, and with the PN sequence input traffic carried out randomization;
A Bose-Chaudhuri-Hocquenghem Code device receives randomized input traffic, and with BCH code randomized data flow is encoded; And
A LDPC encoder receives the data flow of Bose-Chaudhuri-Hocquenghem Code, and with the LDPC sign indicating number Bose-Chaudhuri-Hocquenghem Code data flow is encoded.
3. the TDS-OFDM transmitter based on LDPC as claimed in claim 2 is characterized in that described LDPC sign indicating number comprises a QC-LDPC sign indicating number, and this yard selected from one group of quasi-cyclic LDPC code of different code checks 0.4,0.6,0.8.
4. the TDS-OFDM transmitter based on LDPC as claimed in claim 3, it is characterized in that, described one group of quasi-cyclic LDPC code comprises (7493 of a code check 0.4,3048) QC-LDPC sign indicating number, (7493 of a code check 0.6,4572) QC-LDPC sign indicating number, (7493,6096) QC-LDPC sign indicating number of a code check 0.8.
5. the TDS-OFDM transmitter based on LDPC as claimed in claim 4 is characterized in that, described LDPC encoder produces the bit of 7493 LDPC encoded data streams, and deletion is 5 check bits wherein, produces the bit of 7488 LDPC encoded data streams.
6. the TDS-OFDM transmitter based on LDPC as claimed in claim 1 is characterized in that described TDS-OFDM modulator is operated under the multi-carrier mode, TDS-OFDM modulator composed as follows:
A rate converter receives LDPC coded data stream, and the bit of encoded data stream is merged into byte, and adjusts the speed of byte output clock;
A time domain interleaver, the data flow of acceptance rate transducer output, and carry out the convolution expansion;
An IFFT receives the data flow that the time domain interleaver is exported, and frequency domain information is converted to time-domain signal, and IFFT produces the Frame of OFDM symbol;
A protection interval insert module is inserted the PN sequence in the protection between Frame at interval, each is protected at interval and signal frame of Frame formation; And
A SRRC carries out filtering to signal frame, produces digital baseband signal.
7. the TDS-OFDM transmitter based on LDPC as claimed in claim 1 is characterized in that described TDS-OFDM modulator is operated under the single carrier mode, TDS-OFDM modulator composed as follows:
A rate converter receives LDPC coded data stream, and the bit of encoded data stream is merged into byte, and adjusts the speed of byte output clock;
A time domain interleaver, the data flow of acceptance rate transducer output, and carry out the convolution expansion;
A protection interval insert module is inserted the PN sequence in the protection between Frame at interval, each is protected at interval and signal frame of Frame formation; And
A SRRC carries out filtering to signal frame, produces digital baseband signal.
8. the TDS-OFDM transmitter based on LDPC as claimed in claim 6 is characterized in that the length of described IFFT is fixed as 3780 symbols, and the LDPC code word is also adjusted down 3780 symbol lengths of IFFT.
9. the TDS-OFDM transmitter based on LDPC as claimed in claim 1 is characterized in that described digital baseband signal is made of digital I and digital Q.
10. a method that produces and transmit based on the TDS-OFDM modulation signal of LDPC is characterized in that, is made of following steps:
Receive MPEG-2 and transmit stream as input traffic;
With pseudo random sequence input traffic is carried out randomization;
With BCH code randomized data flow is encoded;
With the LDPC sign indicating number Bose-Chaudhuri-Hocquenghem Code data flow is encoded; And
With the TDS-OFDM modulation system LDPC encoded data stream is modulated, produced digital baseband signal, digital baseband signal is made up of signal frame, and each signal frame comprises one as protection PN sequence at interval.
11. generation as claimed in claim 10 and transmission is characterized in that based on the method for the TDS-OFDM modulation signal of LDPC, described the LDPC encoded data stream modulated, and when being modulated to multi-carrier modulation, comprising:
The LDPC encoded data stream is carried out the rate conversion;
Rate data converted stream is carried out the convolution expansion;
Carry out inverse fast fourier transformed, frequency domain information is converted to time-domain signal, produce the Frame of OFDM symbol;
Insert the PN sequence in the protection at interval of Frame, a protection interval and a Frame constitute a signal frame; And
With the SRRC filter signal frame is carried out filtering, produce digital baseband signal.
12. generation as claimed in claim 11 and transmission are based on the method for the TDS-OFDM modulation signal of LDPC, it is characterized in that, describedly the LDPC encoded data stream is carried out rate conversion comprise the encoded data stream bit is merged into byte, and adjust the speed of byte output clock.
13. generation as claimed in claim 10 and transmission is characterized in that based on the method for the TDS-OFDM modulation signal of LDPC, described the LDPC encoded data stream modulated, and when being modulated to single-carrier modulated, comprising:
The LDPC encoded data stream is carried out the rate conversion;
Rate data converted stream is carried out the convolution expansion;
Insert the PN sequence in the protection at interval of Frame, Frame of estrangement constitutes a signal frame between a protection; And
With the SRRC filter signal frame is carried out filtering, produce digital baseband signal.
14. generation as claimed in claim 12 and transmission are based on the method for the TDS-OFDM modulation signal of LDPC, it is characterized in that, describedly the LDPC encoded data stream is carried out rate conversion comprise the encoded data stream bit is merged into byte, and adjust the speed of byte output clock.
15. generation as claimed in claim 10 and transmission is characterized in that based on the method for the TDS-OFDM modulation signal of LDPC, describedly the later data flow of Bose-Chaudhuri-Hocquenghem Code is carried out the LDPC coding comprises and delete a surplus N check bit.
16. generation as claimed in claim 10 and transmission is characterized in that based on the method for the TDS-OFDM modulation signal of LDPC described LDPC sign indicating number comprises a QC-LDPC sign indicating number, this yard selected from one group of quasi-cyclic LDPC code of different rates 0.4,0.6,0.8.
17. generation as claimed in claim 16 and transmission are based on the method for the TDS-OFDM modulation signal of LDPC, it is characterized in that, described one group of quasi-cyclic LDPC code comprises (7493 of a code check 0.4,3048) QC-LDPC sign indicating number, (7493 of a code check 0.6,4572) QC-LDPC sign indicating number, (7493,6096) QC-LDPC sign indicating number of a code check 0.8.
18. generation as claimed in claim 17 and transmission are based on the method for the TDS-OFDM modulation signal of LDPC, it is characterized in that, describedly the later data flow of Bose-Chaudhuri-Hocquenghem Code is carried out LDPC coding comprise that encoded data stream produces the bit of 7493 LDPC encoded data streams, deletion is 5 check bits wherein, produce the bit of 7488 LDPC encoded data streams.
19. generation as claimed in claim 10 and transmission is characterized in that based on the method for the TDS-OFDM modulation signal of LDPC described digital baseband signal is made of digital I and digital Q.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82031606P | 2006-07-25 | 2006-07-25 | |
| US60/820,316 | 2006-07-25 | ||
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| CN101420410B (en) * | 2008-10-27 | 2010-12-22 | 宁波大学 | Interference resistant modulation method for digital television terrestrial broadcast transmitter |
| CN101931796B (en) * | 2009-06-22 | 2012-07-04 | 北京北广科技股份有限公司 | Full frequency algorithm in digital television channel processing system |
| CN103001906A (en) * | 2011-09-13 | 2013-03-27 | 清华大学 | TDS-OFDM (time domain synchronous-orthogonal frequency division multiplexing) interfering signal generation method |
| CN103716145A (en) * | 2009-01-29 | 2014-04-09 | Lg电子株式会社 | Apparatus for transmitting and receiving a signal and method of transmitting and receiving a signal |
| CN104836767A (en) * | 2015-04-13 | 2015-08-12 | 江苏技睿通信科技有限公司 | Millimeter waves indoor communication system capable of flexibly configuring guard interval |
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| CN106874139A (en) * | 2015-12-10 | 2017-06-20 | 联发科技（新加坡）私人有限公司 | It is a kind of for error checking and the decoding method corrected, device and processor |
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| CN101420410B (en) * | 2008-10-27 | 2010-12-22 | 宁波大学 | Interference resistant modulation method for digital television terrestrial broadcast transmitter |
| CN103716145A (en) * | 2009-01-29 | 2014-04-09 | Lg电子株式会社 | Apparatus for transmitting and receiving a signal and method of transmitting and receiving a signal |
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| CN101931796B (en) * | 2009-06-22 | 2012-07-04 | 北京北广科技股份有限公司 | Full frequency algorithm in digital television channel processing system |
| CN103001906A (en) * | 2011-09-13 | 2013-03-27 | 清华大学 | TDS-OFDM (time domain synchronous-orthogonal frequency division multiplexing) interfering signal generation method |
| CN103001906B (en) * | 2011-09-13 | 2015-02-18 | 清华大学 | TDS-OFDM (time domain synchronous-orthogonal frequency division multiplexing) interfering signal generation method |
| WO2015192681A1 (en) * | 2014-06-17 | 2015-12-23 | 华为技术有限公司 | Method and device for synchronizing data transmission |
| CN106034244A (en) * | 2015-03-20 | 2016-10-19 | 上海数字电视国家工程研究中心有限公司 | Signal coding and modulating method and demodulating and decoding method and device |
| CN106878766A (en) * | 2015-03-20 | 2017-06-20 | 上海数字电视国家工程研究中心有限公司 | Signalling coding modulating device and demodulation code translator |
| CN106034244B (en) * | 2015-03-20 | 2018-12-18 | 上海数字电视国家工程研究中心有限公司 | Signalling coding modulator approach and demodulation interpretation method and device |
| CN104836767A (en) * | 2015-04-13 | 2015-08-12 | 江苏技睿通信科技有限公司 | Millimeter waves indoor communication system capable of flexibly configuring guard interval |
| CN106874139A (en) * | 2015-12-10 | 2017-06-20 | 联发科技（新加坡）私人有限公司 | It is a kind of for error checking and the decoding method corrected, device and processor |
| US11601313B2 (en) * | 2018-12-28 | 2023-03-07 | Hughes Network Systems, Llc | Efficient cyclic prefix generation with half tone offset |
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