WO2010047514A2 - Appareil pour transmettre et recevoir un signal et procédé de transmission et de réception de signal - Google Patents

Appareil pour transmettre et recevoir un signal et procédé de transmission et de réception de signal Download PDF

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Publication number
WO2010047514A2
WO2010047514A2 PCT/KR2009/006058 KR2009006058W WO2010047514A2 WO 2010047514 A2 WO2010047514 A2 WO 2010047514A2 KR 2009006058 W KR2009006058 W KR 2009006058W WO 2010047514 A2 WO2010047514 A2 WO 2010047514A2
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WIPO (PCT)
Prior art keywords
preamble
data
pilots
data symbols
bits
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PCT/KR2009/006058
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English (en)
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WO2010047514A3 (fr
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Woo Suk Ko
Sang Chul Moon
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Lg Electronics Inc.
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Publication of WO2010047514A3 publication Critical patent/WO2010047514A3/fr

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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
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H04L27/3411—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power reducing the peak to average power ratio or the mean power of the constellation; Arrangements for increasing the shape gain of a signal set
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • 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
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • H04L27/26132—Structure of the reference signals using repetition

Definitions

  • the present invention relates to a method for transmitting and receiving a signal and an apparatus for transmitting and receiving a signal, and more particularly, to a method for transmitting and receiving a signal and an apparatus for transmitting and receiving a signal with pilot distances changed for enhanced efficiency.
  • a digital television (DTV) system can receive a digital broadcasting signal and provide a variety of supplementary services to users as well as a video signal and an audio signal.
  • Digital Video Broadcasting (DVB)-C2 is the third specification to join DVB's family of second generation transmission systems. Developed in 1994, today DVB-C is deployed in more than 50 million cable tuners worldwide. In line with the other DVB second generation systems, DVB-C2 uses a combination of Low-density parity-check (LDPC) and BCH codes. This powerful Forward Error correction (FEC) provides about 5dB improvement of carrier-to-noise ratio over DVB-C. Appropriate bit-interleaving schemes optimize the overall robustness of the FEC system. Extended by a header, these frames are called Physical Layer Pipes (PLP). One or more of these PLPs are multiplexed into a data slice. Two dimensional interleaving (in the time and frequency domains) is applied to each slice enabling the receiver to eliminate the impact of burst impairments and frequency selective interference such as single frequency ingress.
  • PLP Physical Layer Pipes
  • the present invention relates to a digital transmission system and a physial layer signalling architectures.
  • the present invention relates to QAM (Quadruture Amplitude Modulation) method and a method of combining a modification of QAM using BRGC (Binary Reflected Gray Code) and a modification using non-uniform modulation.
  • QAM Quadrature Amplitude Modulation
  • BRGC Binary Reflected Gray Code
  • the present invention provides an efficient scattered pilot pattern and a preamble architecture and a decoder for them in a digital transmission system with enhanced spectrum efficiency using channel bonding method.
  • the present invention provides a preamble architecture for obtaining higher coding gain by increasing spectrum efficiency, and a decoder for efficiently decoding them.
  • the present invention suggests a scattered pilot pattern which can be used for the above efficient preamble architecture and a decoder for it.
  • a scattered pilot pattern which can be used for the above efficient preamble architecture and a decoder for it.
  • any of L1 signal trasported in a preamble of any tuner window positions can be decoded without using channel bonding information.
  • the present invention suggests an L1 signalling architecture which optimizes the above channel bonding system to reduce signalling overhead and an efficient decoder for them.
  • the present invention is directed to a method for transmitting and receiving a signal and an apparatus for transmitting and receiving a signal that substantially obviate one or more problems due to limitations and disadvantages of the related art.
  • An object of the present invention is to provide a method of transmitting broadcasting signal to a receiver having data for service and preamble data, the method comprising: mapping bits of preamble data into preamble data symbols and bits of data into data symbols; building at least one data slice based on the data symbols; building a signal frame based on the preamble data symbols and the data slice; modulating the signal frame by an Orthogonal Frequency Division Multiplexing (OFDM) method; and transmitting the modulated signal frame, wherein the modulated signal frame comprise at least one preamble pilots for the preamble data symbols and at least one scattered pilots for the data symbols, and the positions of the scattered pilots are regular and coincident with the positions of the preamble pilots.
  • OFDM Orthogonal Frequency Division Multiplexing
  • Another aspect of the present invention provides a method of receiving broadcasting signal, the method comprising; demodulating received signals by use of an Orthogonal Frequency Division Multiplexing(OFDM) method; detecting a signal frame from the demodulated signals, the signal frame comprising preamble symbols and data symbols; demapping into bits for the preamble symbols and bits for the data symbols; and decoding the bits for the preamble symbols by a shortened and a Punctured LDPC(Low Density Parity Check) decoding scheme, wherein the modulated signal frame comprise at least one preamble pilots for the preamble data symbols and at least one scattered pilots for the data symbols, and the positions of the scattered pilots are regular and coincident with the positions of the preamble pilots.
  • OFDM Orthogonal Frequency Division Multiplexing
  • Yet another aspect of the present invention provides a transmitter of transmitting broadcasting signal having data for service and preamble data to a receiver, the transmitter comprising: a mapper configured to map bits of preamble data into preamble data symbols and bits of data into data symbols; a data slice builder configured to build at least one data slice based on the data symbols; a frame builder configured to build a signal frame based on the preamble data symbols and the data slice; a modulator configured to Modulate the signal frame by an Orthogonal Frequency Division Multiplexing (OFDM) method; and a transmission unit configured to transmit the modulated signal frame, wherein the modulated signal frame comprise at least one preamble pilots for the preamble data symbols and at least one scattered pilots for the data symbols, and the positions of the scattered pilots are regular and coincident with the positions of the preamble pilots.
  • OFDM Orthogonal Frequency Division Multiplexing
  • Yet another aspect of the present invention provides a receiver of receiving broadcasting signal, the receiver comprising: a demodulator configured to demodulate received signals by use of an Orthogonal Frequency Division Multiplexing(OFDM) method; a frame parser configured to obtain a signal frame from the demodulated signals, the signal frame comprising preamble symbols and data symbols, a demapper configured to demap the obtained signal frame into bits for the preamble symbols and bits for the data symbols; and a decoder configured to decode the bits for the preamble symbols by a shortened and punctured LDPC(low density parity check) decoding scheme, wherein the modulated signal frame comprise at least one preamble pilots for the preamble data symbols and at least one scattered pilots for the data symbols, and the positions of the scattered pilots are regular and coincident with the positions of the preamble pilots.
  • OFDM Orthogonal Frequency Division Multiplexing
  • Fig. 1 is an example of 64- Quadrature amplitude modulation (QAM) used in European DVB-T.
  • QAM Quadrature amplitude modulation
  • Fig. 2 is a method of Binary Reflected Gray Code (BRGC).
  • BRGC Binary Reflected Gray Code
  • Fig. 3 is an output close to Gaussian by modifying 64-QAM used in DVB-T.
  • Fig. 4 is Hamming distance between Reflected pair in BRGC.
  • Fig. 5 is characteristics in QAM where Reflected pair exists for each I axis and Q axis.
  • Fig. 6 is a method of modifying QAM using Reflected pair of BRGC.
  • Fig. 7 is an example of modified 64/256/1024/4096-QAM.
  • Figs. 8-9 are an example of modified 64-QAM using Reflected Pair of BRGC.
  • Figs. 10-11 are an example of modified 256-QAM using Reflected Pair of BRGC.
  • Figs. 12-13 are an example of modified 1024-QAM using Reflected Pair of BRGC(0 ⁇ 511).
  • Figs. 14-15 are an example of modified 1024-QAM using Reflected Pair of BRGC(512 ⁇ 1023).
  • Figs. 16-17 are an example of modified 4096-QAM using Reflected Pair of BRGC(0 ⁇ 511).
  • Figs. 18-19 are an example of modified 4096-QAM using Reflected Pair of BRGC(512 ⁇ 1023).
  • Figs. 20-21 are an example of modified 4096-QAM using Reflected Pair of BRGC(1024 ⁇ 1535).
  • Figs. 22-23 are an example of modified 4096-QAM using Reflected Pair of BRGC(1536 ⁇ 2047).
  • Figs. 24-25 are an example of modified 4096-QAM using Reflected Pair of BRGC(2048 ⁇ 2559).
  • Figs. 26-27 are an example of modified 4096-QAM using Reflected Pair of BRGC(2560 ⁇ 3071).
  • Figs. 28-29 are an example of modified 4096-QAM using Reflected Pair of BRGC(3072 ⁇ 3583).
  • Figs. 30-31 are an example of modified 4096-QAM using Reflected Pair of BRGC(3584 ⁇ 4095).
  • Fig. 32 is an example of Bit mapping of Modified-QAM where 256-QAM is modified using BRGC.
  • Fig. 33 is an example of transformation of MQAM into Non-uniform constellation.
  • Fig. 34 is an example of digital transmission system.
  • Fig. 35 is an example of an input processor.
  • Fig. 36 is an information that can be included in Base band (BB).
  • Fig. 37 is an example of BICM.
  • Fig. 38 is an example of shortened/punctured encoder.
  • Fig. 39 is an example of applying various constellations.
  • Fig. 40 is another example of cases where compatibility between conventional systems is considered.
  • Fig. 41 is a frame structure which comprises preamble for L1 signaling and data symbol for PLP data.
  • Fig. 42 is an example of frame builder.
  • Fig. 43 is an example of pilot insert (404) shown in Fig. 4.
  • Fig. 44 is a structure of SP.
  • Fig. 45 is a new SP structure or Pilot Pattern PP5'
  • Fig. 46 is a suggested PP5' structure.
  • Fig. 47 is a relationship between data symbol and preamble.
  • Fig. 48 is another relationship between data symbol and preamble.
  • Fig. 49 is an example of cable channel delay profile.
  • Fig. 51 is an example of modulator based on OFDM.
  • Fig. 52 is an example of preamble structure.
  • Fig. 53 is an example of Preamble decoding.
  • Fig. 54 is a process for designing more optimized preamble.
  • Fig. 55 is another example of preamble structure
  • Fig. 56 is another example of Preamble decoding.
  • Fig. 57 is an example of analog processor.
  • Fig. 58 is an example of digital receiver system.
  • Fig. 59 is an example of analog processor used at receiver.
  • Fig. 60 is an example of demodulator.
  • Fig. 61 is an example of frame parser.
  • Fig. 62 is an example of BICM demodulator.
  • Fig. 63 is an example of LDPC decoding using shortening / puncturing.
  • Fig. 64 is an example of output processor.
  • service is indicative of either broadcast contents which can be transmitted/received by the signal transmission/reception apparatus.
  • Quadrature amplitude modulation using Binary Reflected Gray Code (BRGC) is used as modulation in a broadcasting transmission environment where conventional Bit Interleaved Coded Modulation (BICM) is used.
  • BICM Bit Interleaved Coded Modulation
  • Fig. 1 shows an example of 64-QAM used in European DVB-T.
  • BRGC can be made using the method shown in Fig. 2.
  • An n bit BRGC can be made by adding a reverse code of (n-1) bit BRGC (i.e., reflected code) to a back of (n-1) bit, by adding 0s to a front of original (n-1) bit BRGC, and by adding 1s to a front of reflected code.
  • the BRGC code made by this method has a Hamming distance between adjacent codes of one (1).
  • the Hamming distance between a point and the four points which are most closely adjacent to the point is one (1) and the Hamming distance between the point and another four points which are second most closely adjacent to the point, is two (2).
  • Such characteristics of Hamming distances between a specific constellation point and other adjacent points can be dubbed as Gray mapping rule in QAM.
  • AWGN Additive White Gaussian Noise
  • Fig. 3 shows an output close to Gaussian by modifying 64-QAM used in DVB-T.
  • Such constellation can be dubbed as Non-uniform QAM (NU-QAM).
  • Gaussian Cumulative Distribution Function can be used to make a constellation of Non-uniform QAM.
  • QAM can be divided into two independent N-PAM.
  • N-PAM By dividing Gaussian CDF into N sections of identical probability and by allowing a signal point in each section to represent the section, a constellation having Gaussian distribution can be made.
  • coordinate xj of newly defined non-uniform N-PAM can be defined as follows:
  • Fig. 3 is an example of transforming 64QAM of DVB-T into NU-64QAM using the above methods.
  • Fig. 3 represents a result of modifying coordinates of each I axis and Q axis using the above methods and mapping the previous constellation points to newly defined coordinates.
  • One embodiment of the present invention can modify QAM using BRGC by using characteristics of BRGC.
  • the Hamming distance between Reflected pair in BRGC is one because it differs only in one bit which is added to the front of each code.
  • Fig. 5 shows the characteristics in QAM where Reflected pair exists for each I axis and Q axis. In this figure, Reflected pair exists on each side of the dotted black line.
  • an average power of a QAM constellation can be lowered while keeping Gray mapping rule in QAM.
  • the minimum Euclidean distance in the constellation can be increased.
  • Fig. 6 shows a method of modifying QAM using Reflected pair of BRGC.
  • Fig. 6a shows a constellation and
  • Fig. 6b shows a flowchart for modifying QAM using Reflected pair of BRGC.
  • a target point which has the highest power among constellation points needs to be found.
  • Candidate points are points where that target point can move and are the closest neighbor points of the target point's reflected pair.
  • an empty point i.e., a point which is not yet taken by other points
  • the power of the target point and the power of a candidate point are compared. If the power of the candidate point is smaller, the target point moves to the candidate point.
  • Fig. 7 shows an example of modified 64/256/1024/4096-QAM.
  • the Gray mapped values correspond to Figs. 8 ⁇ 31 respectively.
  • other types of modified QAM which enables identical power optimization can be realized. This is because a target point can move to multiple candidate points.
  • the suggested modified QAM can be applied to, not only the 64/256/1024/4096-QAM, but also cross QAM, a bigger size QAM, or modulations using other BRGC other than QAM.
  • Fig. 32 shows an example of Bit mapping of Modified-QAM where 256-QAM is modified using BRGC.
  • Fig. 32a and Fig. 32b show mapping of Most Significant Bits (MSB). Points designated as filled circles represent mappings of ones and points designated as blank circles represent mappings of zeros. In a same manner, each bit is mapped as shown in figures from (a) through (h) in Fig. 32, until Least Significant Bits(LSB) are mapped.
  • Modified-QAM can enable bit decision using only I or Q axes as conventional QAM, except for a bit which is next to MSB (Fig. 32c and Fig. 32d).
  • a simple receiver can be made by partially modifying a receiver for QAM.
  • An efficient receiver can be implemented by checking both I and Q values only when determining bit next to MSB and by calculating only I or Q for the rest of bits. This method can be applied to Approximate LLR, Exact LLR, or Hard decision.
  • Non-uniform constellation or NU-MQAM can be made.
  • Pj can be modified to fit MQAM.
  • MQAM two PAMs having I axis and Q axis can be considered.
  • the number of points changes in MQAM. If a number of points that corresponds to jth value of PAM is defined as nj in a MQAM where a total of M constellation points exist, then Pj can be defined as follows:
  • MQAM can be transformed into Non-uniform constellation.
  • Pj can be defiend as follows for the example of 256-MQAM.
  • Fig. 33 is an example of transformation of MQAM into Non-uniform constellation.
  • the NU-MQAM made using these methods can retain characteristics of MQAM receivers with modified coordinates of each PAM.
  • an efficient receiver can be implemented.
  • a more noise-robust system than the previous NU-QAM can be implemented.
  • hybridizing MQAM and NU-MQAM is possible.
  • a more noise-robust system can be implemented by using MQAM for an environment where an error correction code with high code rate is used and by using NU-MQAM otherwise.
  • a transmitter can let a receiver have information of code rate of an error correction code currently used and a kind of modulation currently used such that the receiver can demodulate according to the modulation currently used.
  • Fig. 34 shows an example of digital transmission system.
  • Inputs can comprise a number of MPEG-TS streams or GSE (General Stream Encapsulation) streams.
  • An input processor module 101 can add transmission parameters to input stream and perform scheduling for a BICM module 102.
  • the BICM module 102 can add redundancy and interleave data for transmission channel error correction.
  • a frame builder 103 can build frames by adding physical layer signaling information and pilots.
  • a modulator 104 can perform modulation on input symbols in efficient methods.
  • An analog processor 105 can perform various processes for converting input digital signals into output analog signals.
  • Fig. 35 shows an example of an input processor.
  • Input MPEG-TS or GSE stream can be transformed by input preprocessor into a total of n streams which will be independently processed.
  • Each of those streams can be either a complete TS frame which includes multiple service components or a minimum TS frame which includes service component (i.e., video or audio).
  • each of those streams can be a GSE stream which transmits either multiple services or a single service.
  • Input interface module 202-1 can allocate a number of input bits equal to the maximum data field capacity of a Baseband (BB) frame. A padding may be inserted to complete the LDPC/BCH code block capacity.
  • the input stream sync module 203-1 can provide a mechanism to regenerate, in the receiver, the clock of the Transport Stream (or packetized Generic Stream), in order to guarantee end-to-end constant bit rates and delay.
  • the input Transport Streams are delayed by delay compensators 204-1 ⁇ n considering interleaving parameters of the data PLPs in a group and the corresponding common PLP.
  • Null packet deleting modules 205-1 ⁇ n can increase transmission efficiency by removing inserted null packet for a case of VBR (variable bit rate) service.
  • Cyclic Redundancy Check (CRC) encoder modules 206-1 ⁇ n can add CRC parity to increase transmission reliability of BB frame.
  • BB header inserting modules 207-1 ⁇ n can add BB frame header at a beginning portion of BB frame. Information that can be included in BB header is shown in Fig. 36.
  • a Merger/slicer module 208 can perform BB frame slicing from each PLP, merging BB frames from multiple PLPs, and scheduling each BB frame within a transmission frame. Therefore, the merger/slicer module 208 can output L1 signaling information which relates to allocation of PLP in frame.
  • a BB scrambler module 209 can randomize input bitstreams to minimize correlation between bits within bitstreams.
  • the modules in shadow in Fig. 35 are modules used when transmission system uses a single PLP, the other modules in Fig. 35 are modules used when the transmission device uses multiple PLPs.
  • Fig. 37 shows an example of BICM module.
  • Fig. 37a shows data path and Fig. 37b shows L1 path of BICM module.
  • An outer coder module 301 and an inner coder module 303 can add redundancy to input bitstreams for error correction.
  • An outer interleaver module 302 and an inner interleaver module 304 can interleave bits to prevent burst error.
  • the Outer interleaver module 302 can be omitted if the BICM is specifically for DVB-C2.
  • a bit demux module 305 can control reliability of each bit output from the inner interleaver module 304.
  • a symbol mapper module 306 can map input bitstreams into symbol streams.
  • Case 1 shows an example of using only NU-MQAM at low code rate for simplified system implementation.
  • Case 2 shows an example of using optimized constellation at each code rate.
  • the transmitter can send information about the code rate of the error correction code and the constellation capacity to the receiver such that the receiver can use an appropriate constellation.
  • Fig. 40 shows another example of cases where compatibility between conventional systems is considered. In addition to the examples, further combinations for optimizing the system are possible.
  • the ModCod Header inserting module 307 shown in Fig. 37 can take Adaptive coding and modulation (ACM)/Variable coding and modulation (VCM) feedback information and add parameter information used in coding and modulation to a FEC block as header.
  • ACM Adaptive coding and modulation
  • VCM Variariable coding and modulation
  • the Modulation type/Coderate (ModCod) header can include the following information:
  • the Symbol interleaver module 308 can perform interleaving in symbol domain to obtain additional interleaving effects. Similar processes performed on data path can be performed on L1 signaling path but with possibly different parameters (301-1 ⁇ 308-1). At this point, a shortened/punctured code module (303-1) can be used for inner code.
  • Fig. 38 shows an example of LDPC encoding using shortening / puncturing.
  • Shortening process can be performed on input blocks which have less bits than a required number of bits for LDPC encoding as many zero bits required for LDPC encoding can be padded (301c).
  • Zero Padded input bitstreams can have parity bits through LDPC encoding (302c).
  • bitstreams that correspond to original bitstreams zeros can be removed (303c) and for parity bitstreams, puncturing (304c) can be performed according to code-rates.
  • These processed information bitstreams and parity bitstreams can be multiplexed into original sequences and outputted (305c).
  • Fig. 41 shows a frame structure which comprises preamble for L1 signaling and data symbol for PLP data. It can be seen that preamble and data symbols are cyclically generated, using one frame as a unit. Data symbols comprise PLP type 0 which is transmitted using a fixed modulation/coding and PLP type 1 which is transmitted using a variable modulation/coding. For PLP type 0, information such as modulation, FEC type, and FEC code rate are transmitted in preamble (see Fig. 42 Frame header insert 401). For PLP type 1, corresponding information can be transmitted in FEC block header of a data symbol (see Fig. 37 ModCod header insert 307).
  • ModCod overhead can be reduced by 3 ⁇ 4% from a total transmission rate, for PLP type0 which is transmitted at a fixed bit rate.
  • Frame header remover r401 shown in Fig. 61 can extract information on Modulation and FEC code rate and provide the extracted information to a BICM decoding module.
  • ModCod extracting modules, r307 and r307-1 shown in Fig. 62 can extract and provide the parameters necessary for BICM decoding.
  • Fig. 42 shows an example of a frame builder.
  • a frame header inserting module 401 can form a frame from input symbol streams and can add frame header at front of each transmitted frame.
  • the frame header can include the following information:
  • Channel bonding environment is assumed for L1 information transmitted in Frame header and data that correspond to each data slice is defined as PLP. Therefore, information such as PLP identifier, channel bonding identifier, and PLP start address are required for each channel used in bonding.
  • PLP identifier e.g., a PLP type supports variable modulation/coding
  • ModCod field in Frame header if PLP type supports fixed modulation/coding to reduce signaling overhead.
  • a Notch band exists for each PLP, by transmitting the start address of the Notch and its width, decoding corresponding carriers at the receiver can become unnecessary.
  • Fig. 43 shows an example of Pilot Pattern 5 (PP5) applied in a channel bonding environment. As shown, if SP positions are coincident with preamble pilot positions, irregular pilot structure can occur.
  • PP5 Pilot Pattern 5
  • Fig. 43a shows an example of pilot inserting module 404 as shown in Fig. 42.
  • a single frequency band for example, 8 MHz
  • the available bandwidth is 7.61 MHz, but if multiple frequency bands are bonded, guard bands can be removed, thus, frequency efficiency can increase greatly.
  • Fig. 43b is an example of preamble inserting module 504 as shown in Fig. 51 that is transmitted at the front part of the frame and even with channel bonding, the preamble has repetition rate of 7.61 MHz, which is bandwidth of L1 block. This is a structure considering the bandwidth of a tuner which performs initial channel scanning.
  • Pilot Patterns exist for both Preamble and Data Symbols.
  • scattered pilot (SP) patterns can be used.
  • Pilot Pattern 5 (PP5) and Pilot Pattern 7 (PP7) of T2 can be good candidates for frequency-only interpolation.
  • Pilot patterns for preamble can cover all possible pilot positions for initial channel acquisition.
  • preamble pilot positions should be coincident with SP positions and a single pilot pattern for both the preamble and the SP is desired.
  • Preamble pilots could also be used for time-interpolation and every preamble could have an identical pilot pattern. These requirements are important for C2 detection in scanning and necessary for frequency offset estimation with scrambling sequence correlation. In a channel bonding environment, the coincidence in pilot positions should also be kept for channel bonding because irregular pilot structure may degrade interpolation performance.
  • GI guard interval
  • preamble pilot positions can be coincident with every SP positions of data symbol.
  • data slice where a service is transmitted can be determined regardless of 8 MHz bandwidth granularity.
  • transmission starting from SP position and ending at SP position can be chosen.
  • channel estimation module r501 shown in Fig. 60 can perform time interpolation to obtain pilots shown in dotted lines in Fig. 43 and perform frequency interpolation.
  • time interpolation to obtain pilots shown in dotted lines in Fig. 43 and perform frequency interpolation.
  • intervals for non-continuous points of which intervals are designated as 32 in Fig. 43, either performing interpolations on left and right separately or performing interpolations on only one side then performing interpolation on the other side by using the already interpolated pilot positions of which interval is 12 as a reference point can be implemented.
  • data slice width can vary within 7.61 MHz, thus, a receiver can minimize power consumption by performing channel estimation and decoding only necessary subcarriers.
  • Fig. 44 shows another example of PP5 applied in channel bonding environment or a structure of SP for maintaining effective distance x as 12 to avoid irregular SP structure shown in Fig. 43 when channel bonding is used.
  • Fig. 44a is a structure of SP for data symbol and
  • Fig. 44b is a structure of SP for preamble symbol.
  • x is pilot distance between pilots along the carrier index direction in Fig. 45
  • y pilot distance between pilots along the OFDM symbols direction in Fig. 45
  • z is is multiplication of x and y. Physically, x represents a channel delay profile, y represents a Doppler spread and z represents a pilot density. Frequency-only interpolation capability can still be maintained. Pilot positions are depicted in Fig. 45 for comparison with PP5 structure.
  • the proposed new SP patterns can be advantageous in that single SP pattern can be used for both single and bonded channel; no irregular pilot structure can be caused, thus a good channel estimation is possible; both preamble and SP pilot positions can be kept coincident; pilot density can be kept the same as for PP5 and PP7 respectively; and Frequency-only interpolation capability can also be preserved. That is, it is desirable for a good channel estimation that the positions of the scattered pilots are regular and coincident with the positions of the preamble pilots.
  • preamble structure can meet the requirements such as preamble pilot positions should cover all possible SP positions for initial channel acquisition; maximum number of carriers should be 3409 (7.61 MHz) for initial scanning; exactly same pilot patterns and scrambling sequence should be used for C2 detection; and no detection-specific preamble like P1 in T2 is required.
  • data slice position granularity may be modified to 16 carriers rather than 12, thus, less position addressing overhead can occur and no other problem regarding data slice condition, Null slot condition etc can be expected.
  • pilots in every preamble can be used when time interpolation of SP of data symbol is performed. Therefore, channel acquisition and channel estimation at the frame boundaries can be improved.
  • Fig. 47 shows a relationship between data symbol and preamble when preamble structures as shown in Fig. 52 and Fig. 53 are used.
  • L1 block can be repeated by period of 6 MHz.
  • For L1 decoding both frequency offset and Preamble shift pattern should be found. L1 decoding is not possible in arbitrary tuner position without channel bonding information and a receiver cannot differentiate between preamble shift value and frequency offset.
  • a receiver specifically for Frame header remover r401 shown in Fig. 61 to perform L1 signal decoding, channel bonding structure needs to be obtained. Because preamble shift amount expected at two vertically shadowed regions in Fig. 47 is known, time/freq synchronizing module r505 in Fig. 60 can estimate carrier frequency offset. Based on the estimation, L1 signaling path (r308-1 ⁇ r301-1) in Fig. 62 can decode L1.
  • Fig. 48 shows a relationship between data symbol and preamble when the preamble structure as shown in Fig. 55 is used.
  • L1 block can be repeated by period of 8 MHz.
  • Frequency offset can be easily estimated by using known Pseudo Random Binary Sequence (PRBS) sequence.
  • PRBS Pseudo Random Binary Sequence
  • preamble and data symbols are aligned, thus, additional sync search can become unnecessary. Therefore, for a receiver, specifically for the Frame header remover module r401 shown in Fig. 61, it is possible that only correlation peak with pilot scrambling sequence needs to be obtained to perform L1 signal decoding.
  • the time/freq synchronizing module r505 in Fig. 60 can estimate carrier frequency offset from peak position.
  • Fig. 49 shows an example of cable channel delay profile.
  • Slightly less delay coverage may not be an important in cable channel such as DVB-C2 system. For example, it can be 8 ⁇ s for PP5’ and 4 ⁇ s for PP7’ compared to 9.3 ⁇ s (PP5) and 4.7 ⁇ s (PP7). Meaningful delays can be covered by both pilot patterns even in a worst case. For preamble pilot position, no more than all SP positions in data symbol are necessary.
  • Edge carriers could be inserted for closing edge.
  • pilots are aligned at 8 MHz from each edge of the band, every pilot position and pilot structure can be repeated every 8 MHz.
  • this structure can support the preamble structure shown in Fig. 48.
  • "8 MHz" is an example of channel raster for a given system, and in a system which has other channel raster than 8 MHz, the repetition period can be different. That is, according to an embodiement of the present invention, the repetitioin period of the pilots including the preamble pilots and the scattered pilots can be delayed to be repeated with a period which is the same as channel raster of the system.
  • channel estimation module r501 in Fig. 60 can perform channel estimation using interpolation on preamble and data symbols because no irregular pilot pattern can occur, regardless of window position which is decided by data slice locations. At this time, using only frequency interpolation can be enough to compensate channel distortion from delay spread. If time interpolation is performed additionally, more accurate channel estimation can be performed.
  • pilot position and pattern can be repeated based on a period of 8 MHz.
  • a single pilot pattern can be used for both preamble and data symbols. L1 decoding can always be possible without channel bonding knowledge.
  • the proposed pilot pattern may not affect commonality with conventional system such as DVB-T2 because the same pilot strategy of scattered pilot pattern can be used; DVB-T2 already uses 8 different pilot patterns; and no significant receiver complexity can be increased by modified pilot patterns.
  • the period of PRBS can be 2047 (m-sequence); PRBS generation can be reset every 8 MHz, of which the period is 3584; pilot repetition rate of 56 can be also co-prime with 2047; and no PAPR issue can be expected.
  • the new pilot pattern reduces overhead by extending the pilot distance while maintaining capacity of the conventional system.
  • Fig. 51 shows an example of a modulator based on OFDM.
  • Input symbol streams can be transformed into time domain by IFFT module 501.
  • PAPR peak-to-average power ratio
  • ACE Active constellation extension
  • GI inserting module 503 can copy a last part of effective OFDM symbol to fill guard interval in a form of cyclic prefix.
  • Preamble inserting module 504 can insert preamble at the front of each transmitted frame such that a receiver can detect digital signal, frame and acquire time/freq offset acquisition. At this time, the preamble signal can perform physical layer signaling such as FFT size (3 bits) and Guard interval size (3 bits). The Preamble inserting module 504 can be omitted if the modulator is specifically for DVB-C2.
  • Fig. 52 shows an example of a preamble structure for channel bonding, generated at preamble inserting module 504 in Fig. 51.
  • One complete L1 block should be “always decodable” in any arbitrary 7.61 MHz tuning window position and no loss of L1 signaling regardless of tuner window position should occur.
  • L1 blocks can be repeated in frequency domain by period of 6 MHz. Data symbol can be channel bonded for every 8 MHz. If, for L1 decoding, a receiver uses a tuner such as the tuner r603 represented in Fig. 59 which uses a bandwidth of 7.61 MHz, the Frame header remover r401 in Fig. 61 needs to rearrange the received cyclic shifted L1 block (Fig. 53) to its original form. This rearrangement is possible because L1 block is repeated for every 6MHz block.
  • Fig. 53a can be reordered into Fig. 53b.
  • Fig. 54 shows a process for designing a more optimized preamble.
  • the preamble structure of Fig. 52 uses only 6MHz of total tuner bandwidth 7.61 MHz for L1 decoding. In terms of spectrum efficiency, tuner bandwidth of 7.61 MHz is not fully utilized. Therefore, there can be further optimization in spectrum efficiency.
  • Fig. 55 shows another example of preamble structure or preamble symbols structure for full spectrum efficiency, generated at Frame Header Inserting module 504 in Fig. 51.
  • L1 blocks can be repeated in frequency domain by period of 8 MHz.
  • One complete L1 block is still "always decodable" in any arbitrary 7.61 MHz tuning window position. After tuning, the 7.61 MHz data can be regarded as a virtually punctured code. Having exactly the same bandwidth for both the preamble and data symbols and exactly the same pilot structure for both the preamble and data symbols can maximize spectrum efficiency.
  • Other features such as cyclic shifted property and not sending L1 block in case of no data slice can be kept unchanged.
  • the number of active carriers per channel can be different depending upon the counting method as any skilled person in the art would appreciate. That is, in Fig. 46, 3409 active carriers per single channel corresponding to bandwidth of 7.61 MHz are transmitted. However, if not counting either of channel edges, it can be said that the number of carriers per single channel is 3408.
  • Fig. 56 shows a virtually punctured code.
  • the 7.61 MHz data among the 8 MHz L1 block can be considered as punctured coded.
  • Frame header remover r401 in Fig. 61 needs to rearrange received, cyclic shifted L1 block into original form as shown in Fig. 56.
  • L1 decoding is performed using the entire bandwidth of the tuner.
  • a spectrum of the rearranged L1 block can have a blank region within the spectrum as shown in upper right side of Fig. 56 because an original size of L1 block is 8 MHz bandwidth.
  • the block can have a form which appears to be punctured as shown in lower right side of Fig. 56.
  • This L1 block can be decoded at the punctured/shortened decode module r303-1 in Fig. 62.
  • the entire tuner bandwidth can be utilized, thus spectrum efficiency and coding gain can be increased.
  • an identical bandwidth and pilot structure can be used for the preamble and data symbols.
  • the proposed new preamble structure can be advantageous in that it's fully compatible with previously used preamble except that the bandwidth is different; L1 blocks are repeated by period of 8 MHz; L1 block can be always decodable regardless of tuner window position; Full tuner bandwidth can be used for L1 decoding; maximum spectrum efficiency can guarantee more coding gain; incomplete L1 block can be considered as punctured coded; simple and same pilot structure can be used for both preamble and data; and identical bandwidth can be used for both preamble and data.
  • Fig. 57 shows an example of an analog processor.
  • a DAC module 601 can convert digital signal input into analog signal. After transmission frequency bandwidth is up-converted (602) and analog filtered (603) signal can be transmitted.
  • Fig. 58 shows an example of a digital receiver system.
  • Received signal is converted into digital signal at an analog process module r105.
  • a demodulator r104 can convert the signal into data in frequency domain.
  • a frame parser r103 can remove pilots and headers and enable selection of service information that needs to be decoded.
  • a BICM demodulator r102 can correct errors in the transmission channel.
  • An output processor r101 can restore the originally transmitted service stream and timing information.
  • Fig. 59 shows an example of analog processor used at the receiver.
  • a Tuner/AGC module r603 can select desired frequency bandwidth from received signal.
  • a down converting module r602 can restore baseband.
  • An ADC module r601 can convert analog signal into digital signal.
  • Fig. 60 shows an example of demodulator.
  • a frame detecting module r506 can detect the preamble, check if a corresponding digital signal exists, and detect a start of a frame.
  • a time/freq synchronizing module r505 can perform synchronization in time and frequency domains. At this time, for time domain synchronization, a guard interval correlation can be used. For frequency domain synchronization, correlation can be used or offset can be estimated from phase information of a subcarrier that is transmitted in the frequency domain.
  • a preamble removing module r504 can remove preamble from the front of detected frame.
  • a GI removing module r503 can remove guard interval.
  • a FFT module r501 can transform signal in the time domain into signal in the frequency domain.
  • a channel estimation/equalization module r501 can compensate errors by estimating distortion in transmission channel using pilot symbol.
  • the Preamble removing module r504 can be omitted if the demodulator is specifically for DVB-
  • Fig. 61 shows an example of frame parser.
  • a pilot removing module r404 can remove pilot symbol.
  • a freq deinterleaving module r403 can perform deinterleaving in the frequency domain.
  • An OFDM symbol merger r402 can restore data frame from symbol streams transmitted in OFDM symbols.
  • a frame header removing module r401 can extract physical layer signaling from header of each transmitted frame and remove header. Extracted information can be used as parameters for following processes in the receiver.
  • Fig. 62 shows an example of a BICM demodulator.
  • Fig. 62a shows a data path and
  • Fig. 62b shows a L1 signaling path.
  • a symbol deinterleaver r308 can perform deinterleaving in the symbol domain.
  • a ModCod extract r307 can extract ModCod parameters from front of each BB frame and make the parameters available for following adaptive/variable demodulation and decoding processes.
  • a Symbol demapper r306 can demap input symbol streams into bit Log-Likelyhood Ratio (LLR) streams.
  • the Output bit LLR streams can be calculated by using a constellation used in a Symbol mapper 306 of the transmitter as reference point.
  • LLR Log-Likelyhood Ratio
  • the Symbol demapper r306 of the receiver can obtain a constellation using the code rate and constellation capacity information transmitted from the transmitter.
  • the bit mux r305 of the receiver can perform an inverse function of the bit demux 305 of the transmitter.
  • the Inner deinterleaver r304 and outer deinterleaver r302 of the receiver can perform inverse functions of the inner interleaver 304 and outer interleaver 302 of the transmitter, respectively to get the bitstream in its original sequence.
  • the outer deinterleaver r302 can be omitted if the BICM demodulator is specifically for DVB-C2.
  • the inner decoder r303 and outer decoder r301 of the receiver can perform corresponding decoding processes to the inner coder 303 and outer code 301 of the transmitter, respectively, to correct errors in the transmission channel. Similar processes performed on data path can be performed on L1 signaling path, but with different parameters (r308-1 ⁇ r301-1). At this point, as explained in the preamble part, a shortened/punctured code module r303-1 can be used for L1 signal decoding.
  • Fig. 63 shows an example of LDPC decoding using shortening / puncturing.
  • a demux r301a can separately output information part and parity part of systematic code from input bit streams.
  • a zero padding (r302a) can be performed according to a number of input bit streams of LDPC decoder, for the parity part, input bit streams for (r303a) the LDPC decoder can be generated by de-puncturing punctured part.
  • LDPC decoding (r304a) can be performed on generated bit streams, zeros in information part can be removed and output (r305a).
  • Fig. 64 shows an example of output processor.
  • a BB descrambler r209 can restore scrambled (209) bit streams at the transmitter.
  • a Splitter r208 can restore BB frames that correspond to multiple PLP that are multiplexed and transmitted from the transmitter according to PLP path.
  • a BB header remover r207-1 ⁇ n can remove the header that is transmitted at the front of the BB frame.
  • a CRC decoder r206-1 ⁇ n can perform CRC decoding and make reliable BB frames available for selection.
  • a Null packet inserting modules r205-1 ⁇ n can restore null packets which were removed for higher transmission efficiency in their original location.
  • a Delay recovering modules r204-1 ⁇ n can restore a delay that exists between each PLP path.
  • An output clock recovering modules r203-1 ⁇ n can restore the original timing of the service stream from timing information transmitted from the input stream synchronization modules 203-1 ⁇ n.
  • An output interface modules r202-1 ⁇ n can restore data in TS/GS packet from input bit streams that are sliced in BB frame.
  • An output postprocess modules r201-1 ⁇ n can restore multiple TS/GS streams into a complete TS/GS stream, if necessary.
  • the shaded blocks shown in Fig. 64 represent modules that can be used when a single PLP is processed at a time and the rest of the blocks represent modules that can be used when multiple PLPs are processed at the same time.
  • ModCod information in each BB frame header that is necessary for ACM/VCM By transmitting ModCod information in each BB frame header that is necessary for ACM/VCM and transmitting the rest of the physical layer signaling in a frame header, signaling overhead can be minimized.
  • Modified QAM for a more energy efficient transmission or a more noise-robust digital broadcasting system can be implemented.
  • the system can include transmitter and receiver for each example disclosed and the combinations thereof.
  • An Improved Non-uniform QAM for a more energy efficient transmission or a more noise-robust digital broadcasting system can be implemented.
  • a method of using code rate of error correction code of NU-MQAM and MQAM is also described.
  • the system can include transmitter and receiver for each example disclosed and the combinations thereof.
  • the suggested L1 signaling method can reduce overhead by 3 ⁇ 4% by minimizing signaling overhead during channel bonding.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Radio Relay Systems (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

L'invention concerne un procédé de transmission et de réception d'un signal ainsi qu'un appareil pour transmettre et recevoir un signal selon des distances pilotes qui sont modifiées afin d'améliorer l'efficacité. L'invention consiste à modifier les distances pilotes afin d'obtenir d'une coïncidence entre les positions pilotes de préambule pour les symboles de données de préambule, et les positions pilotes dispersées pour les symboles de données, et afin de réduire la surcharge en retardant la distance pilote.
PCT/KR2009/006058 2008-10-21 2009-10-20 Appareil pour transmettre et recevoir un signal et procédé de transmission et de réception de signal WO2010047514A2 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9313531B2 (en) 2010-10-06 2016-04-12 Thomson Licensing Device and method for content delivery adapted for synchronous playbacks
CN111865550A (zh) * 2020-08-12 2020-10-30 雅泰歌思（上海）通讯科技有限公司 基于双路导频的无帧头无线通讯方法

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US7548506B2 (en) * 2001-10-17 2009-06-16 Nortel Networks Limited System access and synchronization methods for MIMO OFDM communications systems and physical layer packet and preamble design
US8040831B2 (en) * 2005-03-04 2011-10-18 Cisco Technology, Inc. Method and system for control channel beamforming
JP2007295356A (ja) * 2006-04-26 2007-11-08 Fujitsu Ltd Ｏｆｄｍａ通信装置
US8208522B2 (en) * 2008-03-07 2012-06-26 Nokia Corporation System and methods for receiving OFDM symbols having timing and frequency offsets

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9313531B2 (en) 2010-10-06 2016-04-12 Thomson Licensing Device and method for content delivery adapted for synchronous playbacks
CN111865550A (zh) * 2020-08-12 2020-10-30 雅泰歌思（上海）通讯科技有限公司 基于双路导频的无帧头无线通讯方法
CN111865550B (zh) * 2020-08-12 2022-12-20 雅泰歌思（上海）通讯科技有限公司 基于双路导频的无帧头无线通讯方法

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