Structure of Japan's Digital Broadcasting Standard

1. Structure of technical standard for digital broadcasting

Generally speaking, Digital broadcasting system is composed by 3 functional blocks, (1) Source coding block, (2) Multiplex block, and (3) Transmission coding block.

The structure of Japan's Digital broadcasting system is shown in Figure 1.

Figure 1: Structure of Japan's Digital Broadcasting system

Figure 1: Structure of Japan's Digital Broadcasting system

Note: both BML and MHP are available, But in Japan now BML is only service in.

As shown in Figure, "Source coding" and "Multiplex" are common for any digital broadcasting media.

For "transmission coding", the different coding technologies are adopted for each transmission media to optimize for transmission characteristics.

Figure 2: Structure of Technical standards for Japan's digital broadcasting

Figure 2: Structure of Technical Standards for Japan's digital broadcasting

Note: Cable transmission system standards are standardized at another consortium

Figure 2 shows the structure of Technical Standards for Japan's digital broadcasting. The standards for satellite / terrestrial broadcasting are standardized at ARIB. The standard of cable transmission system are standardized at another consortium. ARIB standards for digital broadcasting are described in Table 1.

Table 1: ARIB Standard for digital broadcasting
Digital Television Digital Sound Down load(*1)
Satellite Terrestrial Terrestrial Satellite
Transmission System STD-B20 STD-B31 STD-B29 STD-B41 List of Standards for Broadcasting (ARIB website)
Multiplex Coding & Multiplexing   STD-B32
Service Information   STD-B10
Source coding Coding & Multiplexing   STD-B32
Data Broadcasting Presentation Engine (BML)   STD-B24
Execution Engine (GEM-based)   STD-B23
CAS Conditional Access   STD-B25
Home servers System based on Home Servers   STD-B38
Receivers STD-B21 STD-B30 STD-B42
Operational Guidelines TR-B15 TR-B14(*2) TR-B13 TR-B26 List of Technical Reports for Broadcasting (ARIB website)

*1 : These ARIB STD and TR are downloaded from ARIB website.
*2 : The content of TR-B14 Volume 9 Chapter 4 and Appendix A "Technological Explanation" has been updated and the latest version is included in ITU-R Report BT.2209-1.

2. About ISDB-T transmission system

Japanese digital terrestrial broadcasting system adopts excellent technologies on transmission system.
The features of transmission system are as follows:

(1) Efficient frequency utilization
(a) Adopt OFDM transmission system considering SFN operation
(b) Adopt hierarchical transmission to realize the different reception service in the same frequency band.
(2) Mobile / handheld service in one transmission standard
(a) Time interleave: Improve mobile reception quality
(b) Partial reception: handheld service in the same channel
(3) Robustness against interference
(a) Adopt concatenated error correction with plural interleave
(b) Time interleave: very effective against impulse noise
(4) Flexibility for several type of service/reception style
(5) Commonality of TV / audio transmission system
(6) Auxiliary (AC) channel can be used for transmission network management

3. Outline of transmission parameter

ISDB-T transmission system has the flexibility for adjusting various kinds of broadcasting service.
In Table 2, Outline of ISDB-T transmission parameters are shown.

For the details of transmission parameters, see ARIB STD-B31(∗).
∗ : ARIB STD is downloaded from List of Standards for Broadcasting (ARIB website).

Table 2: Parameters of ISDB-T (in case of 6MHz bandwidth)
Item Mode (2k) Mode (4k) Mode (8k)
Number of OFDM segment 13
Useful bandwidth 5.575 MHz 5.573 MHz 5.572 MHz
Carrier spacing 3.968 kHz 1.984 kHz 0.992 kHz
Number of total carriers 1405 2809 5617
Modulation QPSK, 16QAM, 64QAM, DQPSK
Number of symbols / frame 204
Active symbol duration 252 us 504 us 1008 us
Guard interval duration 1/4, 1/8, 1/16, 1/32 of active symbol duration
Inner code Convolutional code (1/2, 2/3, 3/4, 5/6, 7/8)
Outer code RS(204,188)
Time interleave 0 - 0.5 second
Useful bit rate 3.651 - 23.234 Mbps