Multimedia systems and equipment - Multimedia signal transmission - Dependable line code with error correction

IEC TR 63094:2017(E) specifies the line code 4b/10b for dependable multimedia signal transmission required for complex machines, such as robots and automobiles. This document corresponds to the functions specified in layer 1 to layer 2 of the OSI reference model (ISO/IEC 7498).
The purpose of this document is to facilitate the development and use of the 4b/10b in dependable systems by providing a line code protocol. This document provides a line code protocol for interconnections among distributed real-time systems, including embedded systems, control systems, amusement systems, robot systems, and intelligent buildings. The 4b/10b can achieve the line code with ECC (error code correction).

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IEC TR 63094

Edition 1.0 2017-06


Multimedia systems and equipment – Multimedia signal transmission –
Dependable line code with error correction

IEC TR 63094:2017-06(en)

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IEC TR 63094


Edition 1.0 2017-06





Multimedia systems and equipment – Multimedia signal transmission –

Dependable line code with error correction




ICS 33.160.60; 35.110 ISBN 978-2-8322-4337-4

  Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission

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– 2 – IEC TR 63094:2017 © IEC 2017
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 9
4 4b/10b line code . 9
4.1 Overview. 9
4.2 Forward error correction (FEC) . 9
4.3 Embedded clock . 9
4.4 DC balance . 9
4.5 4b/10b data encoding. 10
4.6 Frame format . 10
4.6.1 Frame . 10
4.6.2 Setup command . 10
4.6.3 Idle command . 11
4.7 Encoding. 11
4.8 Decoding . 11
4.9 Error handling . 11
4.9.1 1-bit error . 11
4.9.2 2-bit error . 12
4.9.3 Over 3-bit error . 12
Annex A (informative) Real-time scheduling . 13
Annex B (informative) Characteristics of embedded clock . 14
Annex C (informative) Characteristics of DC balance . 15
Annex D (informative) Implementation of a decoder . 16
Bibliography . 17

Figure 1 – A humanoid robot . 6
Figure A.1 – EDF scheduling . 13

Table 1 – The 4b/10b data transform . 10
Table 2 – Setup command . 10
Table 3 – Idle command . 11
Table 4 – The 4b/10b look-up . 11
Table B.1 – The length of successive 0 or 1 in case of 1-bit error . 14
Table C.1 – An example of the isomery of 0 and 1 in a successive 10-bit window . 15

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IEC TR 63094:2017 © IEC 2017 – 3 –


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IEC TR 63094, which is a technical report, has been prepared by IEC technical committee 100:
Audio, video and multimedia systems and equipment.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
100/2823A/DTR 100/2871/RVDTR

Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

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– 4 – IEC TR 63094:2017 © IEC 2017
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IEC TR 63094:2017 © IEC 2017 – 5 –
This document defines a line code that incorporates error correction capability to
communicate reliably among multimedia components, I/O peripherals and computers. A
number of complex multimedia machines, in particular robots, automobiles, and network
routers, have a growing demand for distributed processing. In addition, modernization of
facilities such as factories, offices, schools, and homes is creating a ubiquitous and
multimedia computing environment. Unlike conventional PC applications for documentation
and Internet applications that exchange texts without hard time constraints, these types of
cooperative computing require reliable real-time responses to physical events occurring in the
real world. In order for distributed nodes to cooperate in real-time, an interconnecting network
shall realize real-time and dependable communication without re-sending on noisy
environments. The 4b/10b provides a dependable line code for such real-time
communications between multimedia components, I/O peripherals and/or computers by
providing embedded clock, DC balance, error detection and error correction features.
The real-time aspect means that the exactness of the system including operations and
communications depends not only on the result, but also on the time it took to achieve the
result. In the narrow sense, the real-time aspect means that the time constraint, including
deadlines or cycles, must be met.
Real-time tasks with the time constraints are generally scheduled and executed by a real-time
scheduler and a real-time operating system. Most real-time scheduling algorithms assume
that the WCET (worst-case execution time) of each task is given. A real-time scheduling
algorithm converts a time constraint of each real-time task to a priority. Most real-time
operating systems based on such real-time schedulers pre-empt and execute tasks in order of
priority at every tick to meet the time constraint.
As real-time scheduling algorithms, the earliest deadline first (EDF) scheduler, the rate
monotonic (RM) scheduler, and their variations have been established, as explained in Annex
A. These algorithms commonly schedule tasks based on priorities determined by the time
Most real-time scheduling algorithms assume that the WCRT (worst-case response time) of
each communication packet is given in case of communication. In order to apply real-time
scheduling algorithms to real-time communications, pre-emptive communication, which is
achieved by Responsive Link (ISO/IEC 24740), and the error correction capability to prevent
the re-sending a broken packet are required.
A line code is a lowest-level communication protocol on a communication line. Most current
line codes have a few typical functions including embedded clock, DC balance and basic error
detection features. The 8b/10b codec is a major example, which is used for PCI Express, USB
3.0, SATA, IEEE1394b, and 10GbE. But no conventional line code has an error correction
When an encoded code (a 10b code) is broken during communication, the multi-bits of the
decoded code (the 8b code) are corrupted. In other words, when a single bit error occurs in
an encoded 10-bit code, the decoded 8-bit code (a byte) is completely broken.
When an error is detected on the decoder, the broken data is normally re-transmitted under
an upper-level communication protocol. However, re-transmission is not allowed in order to
realize real-time communication.
It is hard for a bit-level error correction code that includes the Hamming code and the BCH
code to incorporate error correction capability, because multi-bits of the decoded code are
broken even if a single-bit error occurs on the encoded code.

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– 6 – IEC TR 63094:2017 © IEC 2017
In order to incorporate error correction capability on the 8b/10b codec, a block-level error
correction including RS (Reed-Solomon) is required as a large packet-level error correction.
But the block-level error correction is not suitable for real-time communication, because the
communication latency becomes longer as it is impossible to correct the corrupted data until
all corresponding packets are received.
The line code 4b/10b has the following distinctive features for real

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