DVB-T2

DVB-T2 is fundamentally different from DVB-T in both the system level architecture (MAC layer - Media Access Control ) and the physical layer features, as a result of which DVB-T receivers are incompatible with DVB-T2.

The following features have been developed for DVB-T2:

• OFDM modulation with QPSK , 16- QAM , 64-QAM or 256-QAM groups.
• OFDM modes 1k, 2k, 4k, 8k, 16k, 32k and "32k ext". The character length for 32k mode is about 4 ms.
• Relative lengths of guard intervals: 1/128, 1/32, 1/16, 19/256, 1/8, 19/128 and 1/4. (For 32k mode, a maximum of 1/8).
• Forward Error Correction (FEC) with cascading LDPC and BCH correction codes (as in DVB-S2 and DVB-C2).
• DVB-T2 supports channel bandwidth : 1.7; five; 6; 7; 8 and 10 MHz, moreover, 1.7 MHz is designed for mobile television .
• transmission / reception in MISO mode ( English Multiple Input, Single Output ) using the Alamouti method, that is, the receiver processes signals from two or more transmitting antennas.

The following table compares the available modes in DVB-T and DVB-T2. ^[one]

Maximum data transfer rate with a bandwidth of 8 MHz, 32K subcarriers, with a guard interval of 1/128, PP7 subcarrier layout: ^[2]

The DVB-T standard was designed exclusively for transmitting the MPEG-TS transport stream, but unlike DVB-T, DVB-T2 has the ability to transmit several independent transport streams of different nature and structure. Each digital stream is placed in its main stream - the so-called channel of the physical layer PLP ( Eng. Physical Layer Pipe ). For this, the function of preprocessing input data is introduced.

Input preprocessing

Creating a physical layer channel (PLP) that can contain one of the following flows:

• transport stream (TS) - a sequence of packets of a fixed length
• generalized encapsulated stream (GSE) - packets of variable or fixed length, which is indicated in the headers of these packets
• generalized continuous stream (GCS) - a sequence of packets without specifying their length or a maximum length of 64 kbps.
• generalized stream combined into fixed-length packets (GFPS) - a format for compatibility with DVB-S2, can be replaced by GSE.

Input Processing

Data is collected in groups called streaming ( English Baseband ) frames (BB frames) defined by modulation and coding parameters (MODCOD), in versions of “normal” or “short” length. One or more PLP streams can be transmitted

Bit Interleaved Encoding and Modulation (BICM)

• Forward Error Correction (FEC): Each BB frame is converted to an FEC frame of N _ldpc bits by adding parity data. Normal FEC frames contain 64,800 bits, while short FEC frames contain 16,200 bits. Effective coding ratio 32 208/64 800 (1/2), 38 688/64 800 (3/5), 43 040/64 800 (2/3), 48 408/64 800 (3/4), 51 648 / 64 800 (4/5), 53 840/64 800 (5/6)
  • External coding: Bowes – Chowdhury – Hockingham (BCH) code, capable of correcting 10 or 12 errors in an FEC frame. It is used to calculate the parity of information field data. The BCH generator polynomial has the following degrees: one hundred and sixtieth (160), one hundred and sixty-eighth (168), or one hundred and ninety-second (192).
  • Internal coding: low density parity check (LDPC) code
• Bit interleaving
  • Interleaving a block of parity bits
  • Paging
• Demultiplexing bits in codeword cells
• Gray conversion of codeword cells into a signal constellation : QPSK (4-QAM), 16-QAM, 64-QAM, or 256-QAM transforms are used.
• Constellation rotation and cyclic quadrature (Q) delay: in addition, the constellation can rotate counterclockwise up to 30 degrees. In addition, the quadrature (imaginary) part of the cells is cyclically shifted by one cell
• Cell Interleaving
• Temporary interleaving - used for resistance to impulse noise, various information components are interleaved with a period of about 70 ms.

Shaping

The transmitted stream is organized into superframes, which consist of DVB-T2 frames (up to 255) and parts of the perspective extension frame (FEF). FEFs are used to reserve space for information that may appear in the future and transmitted to OFDM.

• Cell Conversion: Cells are converted to OFDM symbols. The DVB-T2 frame consists of:
  • P1 character - used for synchronization
  • one or more P2 characters - sends the L1 signaling configuration parameter
  • regular data symbols - contain PLP data (there are three types: common PLP, PLP type 1 and PLP type 2), auxiliary streams and dummy characters to fill
  • frame close character (for some parameters)
• Frequency interleaving: random interleaving is done for each OFDM symbol (except P1)

OFDM Generation

• MISO mode ( English multiple input single output - many inputs, one output) was introduced for single-frequency networks: Alamouti preprocessing is additionally applied to pairs of OFDM symbol cells.
• Implement pilot and false tone reservation. Three classes of pilot tones are added: constant (with a fixed position), scattered (cyclically moving position), or edge (boundary position). There are 8 different configurations for the diffuse pilot tone (PP1 ... PP8). In addition, a number of dummy subcarriers are not modulated and reserved to reduce the dynamic range of the DVB-T2 output signal (this reduces non-linear distortion in power amplifiers during transmission).
• Inverse Discrete Fourier Transform (IDFT): The classic IDFT is used to transition from the frequency domain to the time domain, shifting the position of the subcarriers relative to the average carrier frequency. Available from 1k (1024) to 32k (32768) subcarriers. There is also an advanced mode that allows additional data to be filled in the available bandwidth using more active subcarriers and reducing the number of zero guard subcarriers.
• Reducing the ratio of peak power to average (PAPR) - increases the efficiency of the transmitter in power.
• Adding a guard interval: a cyclic prefix is ​​inserted before the IDFT symbol to highlight the signal when there are echoes in the transmission channel. Intervals from 1/128 to 1/4 of the IDFT length are allowed.
• Adding P1 symbol: P1 symbol is a separately created 1k OFDM symbol, always inserted in the frame header. It transmits several bits of information (distribution, scrambling and DBPSK modulation), serves to synchronize (in time and frequency) and identify the stream on the receiving side.
• Digital to Analog Conversion (DAC): DVB-T2 samples are converted to an analog complex BB signal (I and Q). The sampling rate depends on the bandwidth of the allocated frequency band. For example, with a channel width of 8 MHz, the sampling interval of complex samples is 7/64 μs.

DVB-T2 allows you to provide various digital services and services:

• Multi-channel multiplexing ;
• Standard definition television SDTV in aspect ratio 4: 3 and 16: 9 ;
• High Definition Television HDTV ;
• Ultra High Definition Television UHDTV ;
• 3D TV in DVB 3D-TV standard;
• Interactive hybrid television in the HbbTV standard;
• Video on demand ;
• TV guide ;
• Teletext
• Subtitles
• Stereo sound ;
• Surround sound ;
• Dolby Digital Sound;
• Multisound (choice of broadcasting language);
• Digital radio ;
• Synchronization of time and date with digital broadcasting;
• Data transmission in the DVB-DATA standard;
• Direct and reverse communication channels for interactive services in DVB-RCS and DVB-RCT standards ;
• Broadband internet access
• Warning system .

The list contains all digital services and DVB-T2 services. Many digital services and services are interactive .

The digital signal DVB-T2 is received by an etheric collective or individual (outdoor or indoor) antenna connected to various receivers:

• digital or universal TV with support for DVB-T2;
• receiver (TV set-top box) DVB-T2 for a TV or monitor ;
• TV tuner DVB-T2 for computer .

Europe

• Germany: one multiplex (HD), trial launch on May 31, 2016. Regular (commercial) broadcasting will begin on March 29, 2017 ^[3]
• UK: One Multiplex (HDTV), trial launch in December 2009, fully launched in April 2010.
• Italy: one multiplex, trial launch in October 2010.
• Sweden: two multiplexes, full launch in November 2010.
• Finland: five multiplexes, trial launch in January 2011, fully in February 2011.
• Spain: two multiplexes, full launch in 2010.

Russia

DVB-T2 is defined as a standard for digital terrestrial television in the framework of the Federal Target Program “Development of Broadcasting in the Russian Federation for 2009-2018” ^[4] . On March 16, 2012, by the decision of the State Commission on Radio Frequencies for Broadcasting in DVB-T2 standard, the radio frequencies of the meter (174-230 MHz) and decimeter frequency ranges (470-790 MHz) on 6-12 and 21-60 frequency channels, respectively, were adopted ^{[5 ]} .

The sole executor of the work under the federal target program “Development of Broadcasting in the Russian Federation for 2009-2018” was defined as “ Russian Television and Radio Broadcasting Network ” (RTRS) ^[6] . This state-owned operator organized the broadcasting of two multiplexes in the DVB-T2 standard - RTRS-1 and RTRS-2 ^[7] , and expanded broadcasting (regional multiplex) in the Republic of Crimea and Sevastopol ^[8] . Channel packets formed by RTRS are free and open for reception ( FTA ), the conditional access system for signal encryption is not used ^{[9] [10]} . In accordance with the DVB-T2 standard, free, social digital services and services are implemented: standard definition television (SDTV), digital radio, stereo sound, subtitles, teletext, TV guide, time and date synchronization with digital broadcasting.

At the end of 2018, in Russia, the digital television broadcasting system had more than 5 thousand objects and 10 thousand transmitters; in 2019, it was planned to turn off analog broadcasting and switch to DVB-T2. ^{[11] [12]}

Ukraine

In 2010, Odessa ORTPTS organized a test broadcast of one multiplex in the DVB-T2 standard , at the same time Odessa OTRPC applied for a national provider license ^[13] . However, in 2011, only one company, Zeonbud , received a license for a digital television network operator using the DVB-T2 standard ^[14] . In 2011 ^[14] –2015 ^[15] , this operator used the COURT ^[14] Irdeto Cloaked CA under the concept of Free-to-view . Four nationwide FTA multiplexes are being broadcast - MX-1, MX-2, MX-3 and MX-5. Multiplexes consist of 32 television channels, of which 28 are nationwide and 4 regional, 10 high (HDTV) and 22 standard (SDTV) definition; the compression standard is MPEG4 ^[16] .

Belarus

RUE Beltelecom and RUE Belarusian Radio and Television Broadcasting Center in 2013 implemented a joint project of commercial digital broadcasting ^[17] in the DVB-T2 standard - “2nd Multiplex” ^[18] and “3rd Multiplex” ^[19] under ZALA brand. The broadcast began on August 1, 2013 in the cities of Berezino and Krupki , the digital broadcasting network DVB-T2 is being developed in the republic ^[20] . In 2016, RUE “BRTPC” was reorganized by joining RUE “Beltelecom” ^[21] , which from this moment has been a natural monopoly in broadcasting ^[22] .

Kyrgyzstan

In Bishkek ^[23] and in the rest of the republic, digital broadcasting is carried out in the DVB-T2 standard.

Tajikistan

Four state television channels of Tajikistan switched to digital broadcasting - Shabakai Avval (Channel One), Safin Television , Jahonnamo, Bahoriston children's channel ^[24] , as well as Sinamo (Cinema) and Varzish HD (Sport HD). Broadcast in the DVB-T2 standard is carried out in the cities of Dushanbe , Kurgan-Tube , Khujand , Kulyab and Khorog , the coverage area is about 51% ^{[ what? ]} countries. In addition, two independent television channels of the city of Khujand, “Asia” and “SM-1” ^[25] , which later abandoned digital broadcasting, started digital broadcasting.

Armenia

In November 2014, test broadcasting DVB-T2 ^{[26] [27] was} launched in Yerevan and nearby cities.

• DVB-T

• Nick Wells, Chris Knox. DVB-T2: A New Broadcast Standard for High Definition Television // Tele-Sputnik: Journal. - 2008. - No. 11 (157) .
• I. Shakhnovich. DVB-T2 - a new standard for digital television broadcasting // ELECTRONICS: Science, Technology, Business: magazine. - 2009. - No. 6 .
• Alexander Serov. DVB-T2 - second generation digital television // 625: journal. - 2009. - No. 07 . - ISSN 0869-7914 . Archived {a.

• Information on the DVB-T2 standard on the official website of the DVB Consortium
• Information on the DVB-T2 standard on the official website of ROHDE & SCHWARZ