WO2015026547A1 - Mode à faible brouillage par le canal adjacent pour un système de télévision numérique - Google Patents

Mode à faible brouillage par le canal adjacent pour un système de télévision numérique Download PDF

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Publication number
WO2015026547A1
WO2015026547A1 PCT/US2014/050477 US2014050477W WO2015026547A1 WO 2015026547 A1 WO2015026547 A1 WO 2015026547A1 US 2014050477 W US2014050477 W US 2014050477W WO 2015026547 A1 WO2015026547 A1 WO 2015026547A1
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WIPO (PCT)
Prior art keywords
carriers
bandwidth
carrier
mode
modulated signal
Prior art date
Application number
PCT/US2014/050477
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English (en)
Inventor
John Sidney Stewart
Max Ward Muterspaugh
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Thomson Licensing
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Publication date
Application filed by Thomson Licensing filed Critical Thomson Licensing
Priority to CA2921750A priority Critical patent/CA2921750C/fr
Priority to US14/913,399 priority patent/US11202113B2/en
Priority to MX2016002319A priority patent/MX2016002319A/es
Priority to KR1020167007092A priority patent/KR102364907B1/ko
Publication of WO2015026547A1 publication Critical patent/WO2015026547A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/238—Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
    • H04N21/2383—Channel coding or modulation of digital bit-stream, e.g. QPSK modulation
    • 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
    • H04L25/03821—Inter-carrier interference cancellation [ICI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving MPEG packets from an IP network
    • H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
    • 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
    • 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
    • H04L5/0044—Arrangements for allocating sub-channels of the transmission path allocation of payload
    • 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
    • H04L5/0058—Allocation criteria
    • H04L5/0066—Requirements on out-of-channel emissions

Definitions

  • the present principles relate to communication systems and in particular, to adjacent channel interference in digital television systems.
  • ATSC 3.0 Advanced Television Systems Committee
  • ATSC A/53 which comprises an 8-VSB (8 level, Vestigial Sideband) modulation system.
  • ATSC 3.0 is expected to emerge within the next decade and it intends to support delivery to fixed devices of content with video resolutions up to Ultra High Definition 3840 x2160 at 60 frames per second (fps).
  • the intention of the system is to support delivery to portable, handheld and vehicular devices of content with video resolution up to High Definition 1920x1080 at 60fps.
  • the system is also expected to support lower video resolutions and frame rates.
  • OFDM is a method of encoding digital data on multiple carrier frequencies.
  • the sub-carrier frequencies are chosen so that the sub- carriers are orthogonal to each other, meaning that cross-talk between the subchannels is eliminated and inter-carrier guard bands are not required. This greatly simplifies the design of both the transmitter and the receiver; unlike conventional FDM, a separate filter for each sub-channel is not required.
  • the orthogonality allows for efficient modulator and demodulator implementation using the FFT (Fast Fourier Transform) algorithm on the receiver side, and inverse FFT on the transmitter side.
  • the size of the FFT identifies the number of carriers in the OFDM modulation system. Frequency selective channels are characterized either by their delay spread or coherence bandwidth.
  • a single fade or interference can cause the whole link to fail, but in multi-carrier systems, like OFDM, only a few of the total sub carriers will be affected. This way, multipath fading can be easily eliminated in OFDM, with simpler equalization techniques than in single carrier systems.
  • the present principles describe methods and apparatuses which provide a solution to adjacent channel interference when a multi-carrier modulation system (e.g., OFDM) replaces a legacy modulation system (e.g., ATSC) and co-exists with it for a period of time.
  • the adjacent channel interference can be reduced by blocking (setting to 0) and not using some of the carriers at the edge of the spectrum during the period of transition from the legacy system to the multi-carrier system. This effectively reduces the bandwidth of the channel and consequently, the adjacent channel interference caused by the multi-carrier signal, without the need of complex and expensive filtering, while maintaining compatibility with the spectral mask of the legacy system.
  • the present principles propose a mechanism to allow for the unblocking of the removed carriers once the interference problem becomes less strict, that is, when the legacy system is finally turned off.
  • an apparatus for transmitting a multi-carrier modulated signal including: a source (1 1 1 , 200) for providing data, the data including a bandwidth parameter, the bandwidth parameter including a normal bandwidth mode, at least one reduced bandwidth mode and at least one extended bandwidth mode; and a multi-carrier modulator (1 14) for modulating the data by allocating the data to a plurality of carriers on a physical channel according to the bandwidth parameter to create the modulated signal.
  • the at least one reduced bandwidth mode has a smaller number of carriers than the normal bandwidth mode and the at least one extended bandwidth mode has a larger number of carriers than the normal bandwidth mode.
  • the apparatus may further include: a channel encoder (1 13) for at least channel encoding the data prior to the multi-carrier modulator.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers evenly on both edges of the spectrum of the modulated signal.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers on only one edge of the spectrum of the modulated signal.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers unevenly on both edges of the spectrum of the modulated signal.
  • At least one reduced carrier mode may be used for reducing adjacent channel interference on at least one adjacent channel to the physical channel carrying the multi-carrier signal.
  • At least one adjacent channel may carry a modulated signal satisfying a spectral mask for a legacy communication system.
  • the legacy communication system may be ATSC and the multi-carrier modulation may be OFDM.
  • an apparatus for receiving a multi-carrier modulated signal including: a multi-carrier demodulator (124, 310) for demodulating the modulated signal, the signal including a plurality of signaling data and other than signaling data modulated symbols, the modulated symbols including a plurality of carriers on a physical channel, to obtain demodulated data symbols, wherein demodulating the other than signaling data symbol is performed according to a bandwidth parameter; and a signaling data detector (322) for detecting signaling data from demodulated signaling data symbols and for recovering the bandwidth parameter, the bandwidth parameter including a normal bandwidth mode, at least one reduced bandwidth mode and at least one extended bandwidth mode.
  • the at least one reduced bandwidth mode has a smaller number of carriers than the normal bandwidth mode and the at least one extended bandwidth mode has a larger number of carriers than the normal bandwidth mode.
  • the apparatus may further include: a channel decoder (123, 320) for at least channel decoding the demodulated data symbols after the multi-carrier demodulator.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers evenly on both edges of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers on only one edge of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers unevenly on both edges of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced carrier mode may be used for reducing adjacent channel interference on at least one adjacent channel to the physical channel carrying the multi-carrier signal.
  • At least one adjacent channel may carry a modulated signal satisfying a spectral mask for a legacy communication system.
  • the legacy communication system may be ATSC and the multi-carrier modulation may be OFDM.
  • the demodulator for the signaling data symbols which do not contain the bandwidth parameter may perform demodulation according to the bandwidth parameter.
  • a method for transmitting a multi-carrier modulated signal including: providing data (910), the data including a bandwidth parameter, the bandwidth parameter including a normal bandwidth mode, at least one reduced bandwidth mode and at least one extended bandwidth mode; and multi-carrier modulating (940) the data by allocating the data to a plurality of carriers on a physical channel according to the bandwidth parameter to create the modulated signal.
  • the at least one reduced bandwidth mode has a smaller number of carriers than the normal bandwidth mode and the at least one extended bandwidth mode has a larger number of carriers than the normal bandwidth mode.
  • the method may further include: channel encoding (930) the data prior to multi-carrier modulating.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers evenly on both edges of the spectrum of the modulated signal. At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers on only one edge of the spectrum of the modulated signal. At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers unevenly on both edges of the spectrum of the modulated signal. At least one reduced carrier mode may be used for reducing adjacent channel interference on at least one adjacent channel to the physical channel carrying the multi-carrier signal. The at least one adjacent channel may carry a modulated signal satisfying a spectral mask for a legacy communication system.
  • the legacy communication system may be ATSC and the multi-carrier modulation may be OFDM.
  • a method for receiving a multi-carrier modulated signal including : multi-carrier demodulating (1 01 0) the modulated signal, the signal including a plurality of signaling data and other than signaling data modulated symbols, the modulated symbols including a plurality of carriers on a physical channel, to obtain demodulated data symbols, wherein demodulating the other than signaling data symbol is performed according to a bandwidth parameter; and detecting signaling data (1 030) from demodulated signaling data symbols and for recovering the bandwidth parameter, the bandwidth parameter including a normal bandwidth mode, at least one reduced bandwidth mode and at least one extended bandwidth mode.
  • the at least one reduced bandwidth mode has a smaller number of carriers than the normal bandwidth mode and the at least one extended bandwidth mode has a larger number of carriers than the normal bandwidth mode.
  • the method may further include: channel decoding (1 020) the demodulated data symbols after the multi-carrier demodulator.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers evenly on both edges of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers on only one edge of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced bandwidth mode may be created by eliminating normal bandwidth carriers unevenly on both edges of the spectrum of the modulated signal and the demodulator disregards eliminated carriers.
  • At least one reduced carrier mode may be used for reducing adjacent channel interference on at least one adjacent channel to the physical channel carrying the multi-carrier signal.
  • At least one adjacent channel may carry a modulated signal satisfying a spectral mask for a legacy communication system.
  • the legacy communication system may be ATSC and the multi-carrier modulation may be OFDM. Demodulating the signaling data symbols which do not contain the bandwidth parameter may be performed according to the bandwidth parameter.
  • Figure 1 illustrates a simplified block diagram of a general digital communication system applicable to the digital broadcasting channel
  • FIG. 2 illustrates an exemplary transmitter source according to the present principles
  • Figure 3 illustrates an exemplary demodulator and channel decoder according to the present principles
  • Figure 4 illustrates an exemplary spectrum of the transmission signal as a function of the bandwidth parameter according to the present principles
  • Figure 5 illustrates an exemplary spectrum of the transmission signal according to the present principles for an FFT size parameter of 4K;
  • Figure 6 illustrates an exemplary spectrum of the transmission signal according to the present principles for an FFT size parameter of 8K
  • Figure 7 illustrates an exemplary spectrum of the transmission signal according to the present principles for an FFT size parameter of 1 6K;
  • Figure 8 illustrates an exemplary spectrum of the transmission signal according to the present principles for an FFT size parameter of 32K
  • Figure 9 illustrates a flowchart of a method for transmitting a signal according to the present principles.
  • Figure 1 0 illustrates a flowchart of a method for receiving a signal according to the present principles.
  • the present principles relate to communication systems and in particular, to adjacent channel interference in digital television systems.
  • various elements hereby discussed are well known and will not be described in detail.
  • DVD-T2 Digital Video Broadcasting
  • familiarity with the standards and recommended practices of ETSI EN 302 755 and ETSI TS 1 02 832 is assumed and not described herein.
  • familiarity with digital terrestrial television broadcasting system for the US is assumed and not described herein.
  • familiarity with the standards and recommended practices of ATSC A/53, A/1 53 and A/54 is assumed and not described herein.
  • inventive concept may be implemented using conventional programming techniques, which, as such, will not be described herein.
  • Figure 1 shows a simplified block diagram 1 00 of a general digital communication system applicable to the digital broadcasting channel, independent of the modulation system and system architecture.
  • the transmitter device 1 1 0 includes the following components:
  • a source 1 1 1 for the audio, video, signaling or control and other ancillary data e.g., program guide
  • a source encoder 1 12 including audio and video encoders to compress the audio and video data
  • a channel encoder 1 13 including at least some of the functions of randomizing, interleaving, channel coding and frame mapping to process the compressed, signaling and ancillary digital data for robustness and to add levels of error correcting encoding functionality;
  • a modulator 1 14 to convert the processed digital data into modulation symbols, which can be, for example, VSB (ATSC) or OFDM (DVB-T2).
  • modulation symbols can be, for example, VSB (ATSC) or OFDM (DVB-T2).
  • ATSC VSB
  • D/A digital-to-analog
  • an antenna 1 15 representing the functionalities of up-conversion, RF amplification and over-the-air broadcasting.
  • an antenna for reception 125 which includes the functionalities of over- the-air reception, RF down-conversion and tuning;
  • demodulator 124 to recover the digital data from the modulation symbols and includes the functionalities of analog-to-digital conversion (D/A), gain control, carrier and symbol timing recovery, equalization and header or preamble sync detection;
  • channel decoder 123 to recover the compressed and ancillary data by performing the inverse functionalities of the channel encoder, including error correcting decoding, de-interleaving and de-randomizing;
  • a source decoder 122 to decompress the audio and video data, including video and audio decoders
  • a source encoder 1 12 and a channel encoder 1 13, although common in general communications systems, are not essential for a system according to the present principles.
  • a source decoder 122 and a channel decoder 123 although common in general communications systems, are not essential for a system according to the present principles.
  • the transmitter and receiver may not require an antenna, if the transmission system is other than over-the-air (e.g., over cable).
  • a receiving device includes, but is not limited to: a television, a set-top box, a computer, a mobile phone, an automobile receiver and a tablet.
  • DVB-T Digital Terrestrial Television
  • DVB-T2 uses OFDM (orthogonal frequency division multiplex) modulation with a large number of sub-carriers delivering a robust signal, and offers a range of different modes, making it a very flexible standard.
  • DVB-T2 uses the same error correction coding as used in DVB-S2 and DVB-C2: LDPC (Low Density Parity Check) coding combined with BCH (Bose-Chaudhuri- Hocquengham) coding, offering a very robust signal. The number of carriers, guard interval sizes and pilot signals can be adjusted, so that the overheads can be optimized for any target transmission channel. DVB-T2 offers more robustness, flexibility and at least 50% more efficiency than any other DTT system. It supports SD, HD, UHD, mobile TV, or any combination thereof.
  • LDPC Low Density Parity Check
  • BCH Bose-Chaudhuri- Hocquengham
  • FFT Fast Fourier Transform
  • the DVB-T2 specification allows for either the normal number of carriers or an extended number of carriers to be used. This is signaled to the receiver using one bit of the L1 pre-signaling data. This one-bit field, called BWT_EXT. indicates whether the normal (0) or extended (1 ) carrier set is to be used. The exact number of carriers for each FFT size is given in the DVB-T2 specification.
  • the adjacent channel interference When a new broadcast system is deployed, as it will eventually be the case for ATSC 3.0, one impairment which must be considered is the adjacent channel interference.
  • the present principles propose to reduce or prevent adjacent channel interference by temporarily blocking (setting to 0) and not using (i.e., allocating data to) the carriers at the edges of the channel spectrum during the transition period in which both systems will co-exist. This effectively reduces the bandwidth of the channel and also has the effect of reducing adjacent channel interference caused by the multi-carrier signal without the need of complex and expensive filtering.
  • apparatuses and methods are provided for a transmitter/transmitting and a receiver/receiving of a multi-carrier (e.g., OFDM) modulated signal which will co-exist with a pre-existing modulated signal in a transmission system for a period of time.
  • the transmitter transmits a signal including signaling data including a bandwidth parameter which sets the number of carriers per modulated symbol to be a normal number, a plurality of extended numbers or a plurality of reduced numbers.
  • the choice of the value of the bandwidth parameter and how many carriers to add (or eliminate) per bandwidth extended (or reduced) mode are a function of the pre-existing modulated signal and its installed base of transmitters and receivers.
  • the bandwidth parameter and how many carriers to add (or eliminate) per bandwidth extended (or reduced) mode are also a function of the intended FFT size of the multi-carrier system (which defines the total number of carriers over which the FFT is performed), since the roll-off factor may change with the total number of carriers.
  • the choice of the bandwidth parameter and how many carriers to add (or eliminate) per bandwidth extended (or reduced) mode are also a function of the transmission power, distribution of transmitters in the broadcasting area, topography of the area, geographical allocation of the physical channels to transmitters, etc.
  • Figure 2 shows additional details of the source 1 1 1 of Figure 1 , including the video source 210, audio source 220, other ancillary data source 230 and a signaling data source or generator 240.
  • the various sources may not be co-located and may be provided via various forms of data links (e.g., satellite, cable, microwave).
  • the signaling data source is a function of the communication system and may have a number of fixed parameters as well as variable parameters which can be provided via a user interface or another type of input (e.g., a file, a remote data link).
  • the signaling data source includes a bandwidth parameter 242 which identifies one of the bandwidth modes of operation (normal, reduced or extended).
  • the signaling parameters may or not be channel encoded (in channel encoder 1 13).
  • channel encoder 1 13 For example, in ATSC, signaling data like the field and segment sync are not channel encoded; in DVB-T2 all signaling parameters are channel encoded in the L1 pre and post signaling.
  • the modulator 1 14 creates a multi- carrier modulated signal consisting of a sequence of modulation symbols by allocating data to a plurality of carriers per modulation symbol, for signaling data and non-signaling data (video, audio, other ancillary data).
  • the non-signaling data is allocated to the plurality of carriers per modulation symbol according to the bandwidth parameter mode.
  • modulation symbols which do not include the bandwidth parameter may also be created based on the bandwidth parameter.
  • the bandwidth parameter is sent in a preamble or header symbol for each frame of data, and is used to modulate all the remaining symbols of the multi-carrier transmission system, including the remaining data signaling symbols.
  • the preamble symbol is first demodulated and the bandwidth parameter is recovered or extracted and used to demodulate all the remaining symbols in a frame.
  • the transmitter may establish a desirable bandwidth of operation with a reduced number of carriers per symbol in the multi-carrier channel to minimize, reduce or prevent adjacent channel interference.
  • demodulation 124 is first performed to acquire the signaling data at a signaling data detector and set the receiver parameters accordingly. If the signaling data was channel encoded at the transmitter (at channel encoder 1 13), the signaling data detector must reside inside or after the channel decoder 123; otherwise, it can reside inside or after the demodulator 124.
  • the receiver extracts the various parameters contained in the signaling data to set its various modes of operation associated with its various data related blocks (including but not limited to modulation, e.g., constellation size, FFT size; FEC; interleaving; data distribution within the frame; etc.).
  • the parameters are then sent to the various blocks in order for demodulation and decoding to be performed on the video, audio and other ancillary data.
  • the receiver is set to a mode of operation that is compatible with the transmission system and will know which carriers are present in the multi-carrier signal. When in a reduced carrier mode, the receiver will disregard a pre-determined number of carriers associated with that mode, for a certain FFT size.
  • Figure 3 shows an exemplary block diagram according to the present principles depicting a multi-carrier demodulator 310 and channel decoder 320.
  • the demodulator 310 for all practical purposes, can be shown as composed of two blocks: the signaling data demodulator 312 and the audio/video/ancillary data demodulator 314.
  • the signaling data demodulator 312 demodulates the signaling data symbols and sends the demodulated signaling data symbols to the signaling data detector 322.
  • the signaling data 326 is recovered from several potential levels of interleaving, randomizing and channel encoding for protection of the data against channel impairments.
  • the signaling data 326 is recovered (including the bandwidth parameter), it is then sent to other blocks of the receiver, including the audio/video/ancillary (non- signaling) data demodulator 314 and the audio/video/ancillary data channel decoder 324. These two blocks will demodulate and decode the audio, video and other ancillary (data other than signaling) data symbols as a function of the several signaling data parameters 326, including the bandwidth parameter.
  • the transmitters can set their bandwidth parameters to the normal and/or extended modes of operation. Since the bandwidth parameter is a part of the signaling data, it is transmitted on the stream and the receivers will be able to automatically adjust to the new operation mode, by acquiring the new signaling data and extracting the new bandwidth parameter. That way, the system makes the best utilization of the spectrum at all times and without a major service interruption.
  • the new multi-carrier modulated signal is a DVB-T2 type of signal, that is, a signal that has a frame, super-frame and physical layer pipe (PLP) architecture, modulation, FEC and signaling etc. defined similarly to DVB-T2, but with the addition of some important changes to accommodate new conditions and transmission systems not envisioned by the DVB-T2 standard body.
  • PLP physical layer pipe
  • the present principles can be implemented for DVB-T2 type systems by adding a signaling bit to the pre-existing L1 signaling data, such that the parameter BWT EXT can now be defined as in Table 1 .
  • extended carrier mode implies a larger number of carriers than the normal mode and reduced carrier mode implies a smaller number of carriers than the normal mode.
  • BWT_EXT value is "00"
  • the transmission system operates in normal mode of operation, with a normal number of carriers N 0
  • the BW_EXT value is "01”
  • the system operates in extended carrier mode of operation, with an extended number of carriers N-,
  • the BW_EXT value is "10”
  • the system operates in reduced carrier mode 0, with a reduced number of carriers N 2
  • the BW_EXT value is "1 1 ", the system operates in reduced carrier mode 1 , with a reduced number of carriers N 3 .
  • the number of carriers can be such that: N 3 ⁇ N 2 ⁇ N 0 ⁇ N 1 .
  • Figure 4 shows an exemplary spectrum of the transmission signal according to the present principles derived from a DVB-T2 signal for a 6 MHz channel bandwidth (which is the US channel bandwidth), and FFT size of 32K, for a Normal carrier mode 310, Extended carrier mode 340, Reduced carrier mode 0 320 and Reduced carrier mode 1 330.
  • Figure 4 shows the relationship between the modes in Table 1 and the corresponding bandwidth of their transmitted signal: the smaller the number of carriers, the smaller the bandwidth will be. Therefore, adjacent channel interference can be appropriately dealt with on a system by system basis, by setting the appropriate mode.
  • the pre-existing or legacy modulated signal is the ATSC DTT signal currently in operation in the US and other countries.
  • Ni and N 0 may satisfy the DVB-T2 normal and extended bandwidth settings; N 2 may represent an up to 8% reduction of N 0 and N 3 may represent an up to 15% reduction of N 0 .
  • Table 2 shows the number of carriers of an exemplary system according to the present principles derived from a DVB-T2 system, when N 3 represents a 10-1 1 % reduction of N 0 .
  • N 3 represents a 10-1 1 % reduction of N 0 .
  • the reduction in the number of carriers represents a reduction in occupied bandwidth by 600 KHz and an approximate 1 .5 dB improvement in adjacent channel interference rejection.
  • Figures 5 to 8 show exemplary one-sided symmetrical spectra of the transmission signal of Table 2, for a 6 MHz channel bandwidth and FFT sizes of 4K, 8K, 16 ⁇ and 32 ⁇ , respectively.
  • plots of the Normal (510, 610, 710, 810), Reduced (reduced carrier mode, 520, 620, 720, 820) and Extended modes (when applicable, 640, 740, 840) are shown against the Federal Communications Commission (FCC) mask for the ATSC broadcasting transmission signal (530, 630, 730, 830).
  • FCC Federal Communications Commission
  • Table 3 shows the Adjacent Channel Leakage Power Ratio (ACLR) for the transmission signal of Table 2 and Figures 4 to 7, under the various parameters.
  • ACLR Adjacent Channel Leakage Power Ratio
  • an optimal solution may be accomplished, which satisfies the FCC mask and the broadcasters' demands for high bit rate and performance.
  • the lower FFT modes may be given a 12% reduction, while to higher FFT modes may be given a 9% reduction.
  • the reduction of carriers may be asymmetrical on both sides of the spectrum, may be on just one side of the spectrum and may not need to affect every channel of the spectrum for which the new system applies.
  • its lower adjacent channel is ATSC and the upper adjacent channel is also according to the present principles
  • reduction of carriers may just be applied to the lower side of the spectrum.
  • the reduction of carriers may equivalently be applied to both sides of the spectrum with a shift in center frequency applied to the channel to shift the center frequency towards the upper adjacent channel, therefore more easily satisfying the requirement on the lower adjacent side of the channel and vice-versa.
  • FIG. 9 shows a flowchart 900 of a method for transmitting a signal according to the present principles.
  • data is provided 910, including signaling and non-signaling data from source 1 1 1 or 200.
  • the signaling data includes a bandwidth parameter which is set 920 according to a normal, at least one reduced or or at least one extended mode, as in the example of Table 1 .
  • the data may be encoded 930 according to a source encoder 1 12 and/or channel encoder 1 15.
  • the data is then allocated to multiple carriers in multiple modulation symbols according to the setting of the bandwidth parameter 940.
  • the modulated signal transmitted 950.
  • a reduced bandwidth mode may be created by evenly eliminating normal bandwidth carriers on both edges of the spectrum of the modulated signal.
  • a reduced bandwidth mode may be created by eliminating normal bandwidth carriers on only one edge of the spectrum of the modulated signal. This would be desirable when only one side of the spectrum presents an adjacent channel interference problem.
  • a reduced bandwidth mode may be created by eliminating normal bandwidth carriers unevenly on both edges of the spectrum of the modulated signal. This would be desirable if the two adjacent channels present distinct interference problems.
  • FIG. 10 shows a flowchart 1000 of a method for receiving a signal according to the present principles.
  • the signal is received and initially demodulated 1010 to recover signaling parameters.
  • the signaling parameters and non-signaling data may or may not be channel encoded, in which case they are first channel decoded 1020 to recover the signaling and non-signaling data.
  • the signaling parameters are recovered and identified 1030, they are fed to the various blocks to specifically set up their functionalities according to the values of the parameters.
  • one of the signaling parameters to be recovered is the bandwidth parameter, which will influence the demodulation of additional symbols according to the bandwidth mode set up at the transmitter side.
  • the non-signaling data may be source decoded (or decompressed) 1040 and finally sent to an audio/video display device 1050.
  • the present principles may apply to other multi-carrier modulation systems besides OFDM, e.g., discrete multi-tone (DMT) and to other types of single- carrier or multi-carrier pre-existing or legacy systems besides 8-VSB, e.g., single carrier QAM modulation.
  • DMT discrete multi-tone
  • 8-VSB single carrier QAM modulation
  • the present principles are applicable to other types of communications systems, e.g., Wireless-Fidelity (Wi-Fi), cellular, cable, satellite, etc.
  • Wi-Fi Wireless-Fidelity
  • the inventive concept is also applicable to stationary or mobile receivers. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present principles.

Abstract

L'invention concerne des procédés et des appareils qui permettent de remédier au brouillage par le canal adjacent lorsqu'un système de modulation multiporteuse (ex : OFDM) remplace un système de modulation existant et qu'ils coexistent pendant un certain temps. Le brouillage par le canal adjacent peut être réduit par blocage (réglage à 0) et non-utilisation de certaines des porteuses en bordure de spectre pendant la période de transition. Cela diminue efficacement la largeur de bande du canal, et par conséquent le brouillage par le canal adjacent dû au signal multiporteuse. Toutefois, à un certain moment, le système existant est désactivé, et le brouillage par le canal adjacent sur les canaux d'origine n'est plus important. La présente invention comprend un mécanisme qui permet de débloquer les porteuses supprimées une fois que le problème de brouillage est atténué.
PCT/US2014/050477 2013-08-22 2014-08-11 Mode à faible brouillage par le canal adjacent pour un système de télévision numérique WO2015026547A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA2921750A CA2921750C (fr) 2013-08-22 2014-08-11 Mode a faible brouillage par le canal adjacent pour un systeme de television numerique
US14/913,399 US11202113B2 (en) 2013-08-22 2014-08-11 Low adjacent channel interference mode for a digital television system
MX2016002319A MX2016002319A (es) 2013-08-22 2014-08-11 Modo de interferencia de canal adyacente bajo para un sistema de television digital.
KR1020167007092A KR102364907B1 (ko) 2013-08-22 2014-08-11 디지털 텔레비전 시스템을 위한 낮은 인접 채널 간섭 모드

Applications Claiming Priority (2)

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US201361868786P 2013-08-22 2013-08-22
US61/868,786 2013-08-22

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WO2015026547A1 true WO2015026547A1 (fr) 2015-02-26

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