IEC TS 61334-5-4:2001

Distribution automation using distribution line carrier systems - Part 5-4: Lower layer profiles - Multi-carrier modulation (MCM) profile

Is a technical specification describing the requirements of the multicarrier modulation approach which incorporates the services provided by the physical layer entity and the MAC sublayer with the purpose of building up a set of standards for effective communication on MV and LV network for distribution line carrier systems, in the context of IEC 61334-1-1.
This publication is of high relevance for Smart Grid.

General Information

• Status: Published
• Publication Date: 28-Jun-2001
• ICS: 33.200 - Telecontrol. Telemetering
• Technical Committee: TC 57 - Power systems management and associated information exchange
• Drafting Committee: WG 9 - TC 57/WG 9
• Current Stage: PPUB - Publication issued
• Start Date: 29-Jun-2001
• Completion Date: 30-Jun-2001

Overview

IEC TS 61334-5-4:2001 is a technical specification developed by the International Electrotechnical Commission (IEC) focusing on distribution automation using distribution line carrier (DLC) systems. This document defines the requirements of the multi-carrier modulation (MCM) approach at the physical and data link (MAC) layers, central to ensuring robust and efficient communication over medium voltage (MV) and low voltage (LV) networks. The aim is to support effective, reliable, and flexible communication channels across power distribution lines, forming a crucial part of smart grid infrastructure. Designed within the IEC 61334 standards framework, it supports system interoperability and paves the way for improved automation and monitoring in modern electrical distribution networks.

Key Topics

• Multi-carrier Modulation (MCM):
  The standard describes the principles and benefits of MCM, also referred to as Orthogonal Frequency Division Multiplex (OFDM) or Discrete Multitone (DMT). This modulation scheme allows the transmission of data across multiple subcarriers, improving robustness and bandwidth efficiency.

• Physical Layer and MAC Sublayer:
  The interaction between the physical layer and the Medium Access Control (MAC) sublayer is described in detail, specifying how protocol data units (PDUs) are structured, encoded, and transmitted. Key MAC functions include medium access control, error detection, and routing.

• Robustness and Flexibility:
  MCM is highlighted for its resilience to noise, interference, and channel distortion typical in power line communication. Features like cyclic prefix insertion, convolutional encoding, interleaving, and error correction coding enhance communication reliability.

• Domain-based Communication Architecture:
  The network is organized into logical domains, each managed by a master station, with initiators and slave stations providing flexible, dynamic control of communications.

• Interoperability Considerations:
  The specification aligns with existing IEC standards to ensure compatibility and ease of integration with other distribution automation systems.

Applications

The IEC TS 61334-5-4 guideline is especially relevant in:

• Smart Grid Communications:
  Enables reliable data exchange for monitoring and control applications, essential for distribution automation, fault detection, load management, and remote asset monitoring.

• Power Line Communications (PLC):
  Used for communication over existing electrical distribution lines, reducing the need for dedicated communication infrastructure in MV and LV networks.

• Substation Automation:
  Facilitates the exchange of metering, control, and status data between substations, master control units, and field devices.

• Advanced Metering Infrastructure (AMI):
  Supports robust and flexible communication as part of modern metering systems for enhanced energy management by utilities and consumers.

• Future-proof Distribution Networks:
  Its modular and configurable approach ensures ongoing adaptability as power distribution systems evolve and expand.

Related Standards

IEC TS 61334-5-4:2001 fits within a broader suite of IEC standards for distribution automation, with key references including:

• IEC 61334-1-1:
  General considerations for distribution automation system architecture

• IEC 61334-3-1:
  Mains signalling requirements, frequency bands, and output levels for DLC systems

• IEC 61334-4-1:
  Data communication protocols and reference models vital for aligning lower-layer profiles

Additional closely related standards on power system control and smart grid communications from IEC TC 57 and other organizations further extend its practical impact in utilities automation.

---

Keywords:
IEC TS 61334-5-4, multi-carrier modulation, MCM profile, distribution line carrier, power line communications, MAC sublayer, physical layer, smart grid, distribution automation, communication protocol, MV/LV networks, OFDM, DMT, PLC automation.

Standards Content (Sample)

TECHNICAL IEC
SPECIFICATION
TS 61334-5-4
Fi rs t edition
2001-06
Di stribu tion automati on using
distribution line carrier ssytems –
Part 5-4:
Lower laeyr pr ofiles –
Multi-carrier modul ati on (M CM ) pr ofile
Reference number
IEC/TS 61334-5-4:2001 (E)
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
600 00 seri es. For exam pl e, IEC 34 -1 is now referr ed to as IEC 60034-1.
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
bas e p ublication incorporating am endm ent 1 a nd the bas e pu blication incorp or ating
am endm ents 1 and 2.
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TECHNICAL IEC
SPECIFICATION
TS 61334-5-4
First edition
2001-06
Distribution automation using
distribution line carrier systems –
Part 5-4:
Lower layer profiles –
Multi-carrier modulation (MCM) profile
 IEC 2001  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
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International Electrotechnical Commission
For price, see current catalogue

– 2 –TS 613 34-5-4  IEC:2001(E)
CONT ENTS
FOREWORD . .4
1Scope and obj ect.6
2Normative referenc es .6
3Def initions and abbreviations.6
3.1Def initions .6
3.2Abbreviations .7
4Lower layer pr ofile structure.8
4.1Physical layer.8
4.2MAC sublayer .9
5Physical layer spec if ic at ion.9
5.1Modul ation.9
5. 1.1Purpose.9
5. 1.2The multic arrier m odulation (MCM) principle.9
5.2Physical layer data format . 10
5. 2.1Purpose. 10
5. 2.2Transmission method, overview. 10
5. 2.3Configuration parameters. 11
5. 2.4PHY PDU format, CR C encoding an d padding. 12
5. 2.5Convolutional encoding. 13
5. 2.6Segm entation and interleaving. 14
5. 2.7Preamble. 14
5.2.8Modul ation. 14
5.3PHY servic es . 15
5. 3.1PHY to MAC interface. 15
6MAC sublayer protocol specif ic ation. 17
6.1Overview. 17
6. 1.1MAC communication ne twork archit ec ture. 17
6. 1.2Features of the MAC sublayer. 17
6.2Transmission pr ocedures. 17
6.3MAC servic es . 18
6. 3.1MAC to LLC in terface. 18
6. 3.2MAC layer management in terface. 20
6.4MAC PD U format . 22
6. 4.1MAC control field. 22
6. 4.2Addr ess field. 23
6. 4.3LLC PDU. 23
6.5MAC addresses . 24
6.6Used MAC PD Us . 25
6. 6.1Inf ormation PDU. 25
6. 6.2Repetition control PDU. 25
6.7MAC invalid PDU. 25
6.8MAC pr oc ed ur es . 25
6. 8.1MACphy procedures. 26
6. 8.2MACrore pr ocedures. 26

TS 61334-5-4  IEC:2001(E)– 3 –
6.9 MAC timer values . 30
6.10 MAC state transition diagrams/tables. 30
6.10.1 Startup. 30
6.10.2 MAC sublayer . 31
6.10.3 Non-initiator MAC sublayer . 34
Figure 1 – Layered architecture of the DLC-M protocol stack. 8
Figure 2 – Sample frequency representation of multicarrier modulation . 9
Figure 3 – Transmitter data flow diagram (one telegram). 11
Figure 4 – Block diagram of encoder . 13
Figure 5 – MAC transmission using MAC service class 0 (postponed confirmation) . 18
Figure 6 – MAC transmission using MAC service class 1 or 2 (round-trip delayed
confirmation) . 18
Figure 7 – Example for transmission of a MAC PDU with 1 repetition using MAC
service class 1 or 2 . 27
Figure 8 – Time-sequence chart for (error-free) routing repeater procedure. 28
Figure 9 – MAC startup state diagram . 30
Figure 10 – Initiator MAC state diagram . 31
Figure 11 – Non-initiator MAC state diagram . 34
Table 1 – MAC domain IDs. 24
Table 2 – MAC node IDs . 24
Table 3 – MAC predefined addresses. 24
Table 4 – Mapping to IEC 61334-4-1 predefined MAC addresses . 25
Table 5 – MAC startup state table . 31
Table 6 – MAC startup state description . 31
Table 7 – Initiator MAC state table . 32
Table 8 – Initiator MAC state description . 32
Table 9 – Initiator MAC procedures . 33
Table 10 – Initiator MAC variables. 33
Table 11 – Initiator MAC conditions . 33
Table 12 – Non-initiator MAC state table . 34
Table 13 – Non-initiator MAC state description. 36
Table 14 – Non-initiator MAC procedures . 36
Table 15 – Non-initiator MAC variables . 37
Table 16 – Non-initiator MAC conditions. 37

– 4 –TS 61334-5-4  IEC:2001(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIST RIBUTI ON AUTOMATION USING
DIST RIBUTI ON LINE CARRIER SYSTEMS –
Part 5-4: Low er layer profiles –
Multi-carrier mo dulatio n (MCM) profile
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this technical specification may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
The subject is still under technical development or where, for any other reason, there is
the future but no immediate possibility of an agreement on an International Standard.
IEC 61334-5-4, which is a technical specification, has been prepared by IEC technical
committee 57: Power system control and associated communications.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
57/479/CDV 57/517/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
A bilingual version of this publication may be issued at a later date.

TS 61334-5-4  IEC:2001(E)– 5 –
The committee has decided that the contents of this publication will remain unchanged until
2004. At this date, the publication will be
transformed into an International Standard;
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.
– 6 –TS 61334-5-4  IEC:2001(E)
DISTRIBUTION AUTOMATION USING
DISTRIBUTION LINE CARRIER SYSTEMS –
Part 5-4: Lower layer profiles –
Multi-carrier modulation (MCM) profile
1 Scope and object
This technical specification describes the requirements of the multicarrier modulation (MCM)
approach which incorporates the services provided by the physical layer entity and the MAC
sublayer with the purpose of building up a set of standards for effective communication on MV
and LV network for distribution line carrier (DLC) systems, in the context of IEC 61334-1-1.
Different technical approaches in developing communication systems for DLC communication
are in progress. As a consequence, at present, different lower layer profiles are feasible with
acceptable results in terms of performance and cost-effectiveness. In many cases, the
differences amongst solutions are minor and it is possible to find a common root.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61334. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this part of IEC 61334 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 61334-1-1, Distribution automation using distribution line carrier systems – Part 1:
General considerations – Section 1: Distribution automation system architecture
IEC 61334-3-1, Distribution automation using distribution line carrier systems – Part 3-1:
Mains signalling requirements – Frequency bands and output levels
IEC 61334-4-1, Distribution automation using distribution line carrier systems – Part 4: Data
communication protocols – Section 1: Reference model of the communication system
3 Definitions and abbreviations
3.1 Definitions
For the purpose of this part of IEC 61334, the following definitions apply.
3.1.1
control direction
communication direction from the central system to a field device
3.1.2
domain
logical section of a DLC communication network

TS 61334-5-4  IEC:2001(E)– 7 –
3.1.3
hops
number of routing repetitions required for communication between the master and a specific
station
3.1.4
initiator
a station that controls medium access for one domain. The master station may delegate its
'initiatorship' for a limited time to one of the slave stations registered in its domain
NOTE Being an initiator is a dynamic property of a station.
3.1.5
initiator PDU
a PDU that is sent from an initiator to a non-initiator, possibly using routing repeaters for
multi-hop communication
3.1.6
master station
station that works as communication master for a domain
NOTE Being a master station is a static property of a station.
3.1.7
monitoring direction
communication direction from a field device to the central system
3.1.8
non-initiator
a station that is not in the initiator role
NOTE Being a non-initiator is a dynamic property of a station.
3.1.9
non-initiator PDU
a PDU that is sent from a non-initiator to an initiator, possibly using routing repeaters for
multi-hop transmission
NOTE Non-initiator PDUs are only sent in reaction to initiator PDUs.
3.1.10
routing repetition
re-sending a PDU with a modified address field because the destination station cannot
communicate directly with the source station. The routing repetition procedure does not
involve a network layer but is located in the MAC sublayer instead. A synonymous for routing
repetitions is forwarding in the mobile communications context
3.1.11
slave station
station that works as a communication slave within a domain. It normally operates as non-
initiator, but may be switched to operate as initiator
NOTE Being a slave station is a static property of a station.
3.2 Abbreviations
DLC Distribution line carrier
DMT Discret multitone
HV High voltage
LLC Logical link control
– 8 –TS 61334-5-4  IEC:2001(E)
LMI Layer management interface
LV Low voltage
M_SDU MAC layer service data unit
MCM Multicarrier modulation
MIB Management information base
MV Medium voltage
OFDM Orthogonal frequency division multiplex
P_SDU Physical layer service data unit
PDU Protocol data unit
SDU Service data unit
SMAP System management application process
4 Lower layer profile structure
The MCM lower layer profile exhibits the structure shown in the following figure. This
technical specification describes the function of the physical layer and the MAC sublayer.
SMAP
LLC
LLC
Data link
layer
MACrore
LMI
MAC
MACphy
PHY
Physical
layer
Analog signal processing and coupling
device
IEC  987/01
Figure 1 – Layered architecture of the DLC-M protocol stack
4.1 Physical layer
The physical layer provides services to the MAC sublayer to transfer a MAC protocol data unit
to a remote MAC sublayer entity. It is independent of the physical characteristics and the
implementation of the mains attachment unit.
MIB
TS 61334-5-4  IEC:2001(E)– 9 –
4.2 MAC sublayer
The MAC sublayer provides services to the LLC sublayer and uses services of the physical
layer to transmit LLC PDUs to a remote station. The main functions of the MAC sublayer are
error detection and control of medium access.
Furthermore, it provides means for repeater usage which is transparent to the higher protocol
layers.
For better understanding, the MAC sublayer is further subdivided into two functional units
denoted as MACphy and MACrore. MACphy denotes the part of the MAC sublayer responsible
for interfacing to the physical layer, whereas MACrore denotes the part of the MAC sublayer
that interfaces the LLC sublayer and is responsible for addressing and routing repetitions.
5 Physical layer specification
5.1 Modulation
5.1.1 Purpose
Multicarrier modulation (MCM), also known as orthogonal frequency division multiplex
(OFDM) or discrete multitone (DMT) is a modulation technique which combines an excellent
bandwidth efficiency (high data rates) with the possibility of a very flexible bandwidth
allocation. In combination with error correction coding, MCM is very robust in presence of
narrowband jammers, impulsive noise, and frequency selective attenuation, as typically seen
on power lines.
5.1.2 The multicarrier modulation (MCM) principle
In multicarrier modulation, the channel bandwidth is divided into a number of sub-channels. In
each sub-channel, a carrier is modulated at a much lower data-rate. A multicarrier modulation
scheme can be viewed as consisting of N independently modulated carriers with different
carrier frequencies. If the carrier frequencies are selected appropriately, the various carriers
are orthogonal, so that they do not interfere with each other. A sample representation of a
multicarrier modulated signal in the frequency is shown in figure 2.
Spectrum
Frequency
IEC  988/01
Figure 2 – Sample frequency representation of multicarrier modulation
There are several advantages of the multicarrier modulation scheme as compared to
traditional single carrier or spread spectrum systems:
− MCM achieves a much higher bandwidth efficiency than spread spectrum systems. If the
bandwidth of each carrier is sufficiently small, a data-rate close to the theoretical Shannon
limit can be achieved;
– 10 –TS 61334-5-4  IEC:2001(E)
− MCM allows an extremely flexible allocation and use of a given channel bandwidth. As an
example, the lower and the upper limit of the used frequency band can be easily
configured. In addition, certain frequencies inside this frequency band can be suppressed,
for example to prevent interference with other systems. It is also possible to use two or
more non-contiguous sub-bands for the transmission of a single data stream;
− each of the carriers can be modulated individually, with different modulation schemes, if
appropriate. Typical examples of carrier modulation schemes are FSK, PSK, and QAM,
with a different number of bits per carrier. With this flexible choice, the available signal to
noise ratio can be used optimally for each carrier;
NOTE 1 The peak power required for a large number of carriers is about 10 dB higher than that of a single-carrier
system. However, there are known ways to reduce the peak power of traditional MCM without affecting its
performance.
− MCM is considerably more robust against intersymbol interference (ISI) or group delay
distortion caused by the transmission channel than narrowband systems. This is mainly
due to the fact that the parallel transmission on several carriers leads to a longer symbol
duration. Furthermore, ISI can be completely eliminated by inserting guard intervals or a
cyclic prefix between the symbols;
− MCM is robust in presence of narrowband interferers (continuous wave noise), because
such jammers typically destroy only a single carrier. With proper forward error correction
coding, the destroyed bits can be reconstructed;
− in combination with a well-designed interleaver and forward error correction coding
scheme, MCM can be made robust against impulsive noise.
NOTE 2 This implies a more complex receiver structure, compared with, for example a simple FSK receiver, but
the advantages listed above more than justify the use of MCM. There are FFT-based receiver structures whose
complexity increases with M log M, where M is the number of carriers.
Due to the block processing of the MCM demodulator, an inherent transmission delay is
introduced. However, for typical power line communication applications this delay is
negligible.
5.2 Physical layer data format
5.2.1 Purpose
This clause covers the services required for the PHY layer and the transmission methods
which are used to provide the information flow through the physical channel (power
distribution network).
5.2.2 Transmission method, overview
This subclause specifies the transmission method of the MCM profile. The chosen modulation
scheme is multicarrier differential phase shift keying with I carriers (IC-DPSK). The carrier
frequencies are multiples of 4,5 kHz and the number I and the carrier frequencies are

configurable. I bits per symbol are transmitted, leading to a gross data rate of I⋅4,5 kbit/s. To
increase the robustness with respect to channel impairments, a rate 1/2 convolutional code is
used and the length information and the integrity of a telegram are checked with cyclic
redundancy check codes. The synchronization preamble assures a robust synchronization
even in bad channel conditions.
To improve the performance in channels with a large group delay distortion, a cyclic prefix of
configurable length can be used for the modulation of the payload. The synchronization
preamble is always transmitted without cyclic prefix.
The data is transmitted with 288 k samples per second (64 samples per symbol ). In the
receiver, the signal is sampled at 288 kHz and a 64 point FFT is performed.
When a cyclic prefix is used, there are N samples per symbol.
SS
———————
TS 61334-5-4  IEC:2001(E)– 11 –
It is assumed that the P_SDU Q(m), m = 0.8M–1, Q(m) ∈ [0,1] is to be transmitted with I bits/
symbol using I subcarriers. The length information and the payload are each protected with a
separate CRC. The resulting bit stream is padded and segmented into blocks which are
interleaved and encoded. The data are then prepended by the synchronization sequence and
modulated, see figure 3. A detailed description of each function is given below.
M = # MAC octets
telegram Q(m), m=0.8M-1
P = # padding bits
Y = # PHY blocks
CRC encoding
L = PHY block length
and padding
I = # subcarriers
Ir= # subcarriers in preamble
S(m), m=0.8M+P+59
B = # PHY symbols in payload
N = # samples per symbol (excl. cyclic prefix)
Convolutional
Nss = # samples per symbol (incl. cyclic prefix)
encoder
s(t) = transmitted signal
C(m), m=0.16M+2P+119
Segmentation
B(m,k), m=0.L-1, k=0.Y-1
Interleaver
V(m,k), m=0.L-1, k=0.Y-1
Synchronization
sequence Mapper
Z(m,k), m=0.I-1, k=0.B-1
D(m,k), m=0.Ir-1, k=0.B+23
Differential
encoder
A(m,k), m=0.I-1, k=0.B+24
Modulator
s(t), t=0.24N+B*Nss
IEC  989/01
Figure 3 – Transmitter data flow diagram (one telegram)
5.2.3 Configuration parameters
The physical layer as described below is specified by the following design parameters, which
can be configured in the network or adapted to the changing channel conditions. These
parameters have to be identical in a network to achieve compatibility.
− Number I of subcarriers 1 ≤ I ≤ N/2–1. A typical value is N = 64.
− Indices i to i of subcarriers The subcarrier frequency is i ⋅288 kHz /N, 1 ≤ i ≤ N/2–1. This
1 I x x
permits usage of non-contiguous frequency bands. Theoretical frequency range is from
288 kHz/N to 144–288/N kHz (i.e. excluding i = 0 and i = N/2). Practical frequency range
x x
to be chosen in accordance with IEC 61334-3-1.

– 12 –TS 61334-5-4  IEC:2001(E)
− Phases cos(ϕ ) and sin(ϕ ) to cos(ϕ ) and sin(ϕ ) of each subcarrier ϕ is the carrier phase
1 1 I I x
of the subcarrier at index i . The phases can be chosen to reduce the peak power.
x
Compatibility can be achieved even with different phases.
− Usage flag r to r for preamble of each subcarrier r = 1 indicates that subcarrier x is to be
1 I x
used in the preamble. Otherwise, r = 0.
x
NOTE This definition implies that the set of subcarriers used in the preamble is a subset of the subcarriers used
in the payload.
− Preamble phases cos(ϕ ) and sin(ϕ ) to cos(ϕ ) and sin(ϕ ) of each subcarrier ϕ is the
r1 r1 rI rI rx
carrier phase of the subcarrier at index i to be used in the preamble. ϕ is only
x rx
meaningful for {x| r = 1}. The phases can be chosen to reduce the peak power.
x
Compatibility can be achieved even with different phases.
− Length of cyclic prefix in samples, N This is introduced to cater for large group delay
CP
variations. Range is 0.63, default is 0.
− Block length (L) in bits. Blocks are defined in the segmentation process (see 5.2.6).
5.2.4 PHY PDU format, CRC encoding and padding
The PHY telegram structure is shown here,
Field Preamble LEN RES PAD_LEN LEN_CRC PL PAD PL CRC FLUSH
name
Length 25 8 8 8 16 8M P 16 4
(bits)
Preamble S(m)
Preamble and S(m) are encoded and modulated separately.
5.2.4.1 Preamble
See below.
5.2.4.2 LEN
LEN is the length of S in blocks: LEN = (8M + PAD LEN + 60)/BLOCK LEN
5.2.4.3 RES
The RES field is reserved for future use. It shall contain 0 for the current version.
5.2.4.4 PAD LEN
The PAD LEN field is the length P of the PAD field in bits.
5.2.4.5 LEN CRC
The LEN CRC field U (m), m = 0.15, contains the CRC checksum over the fields LEN, RES
L
and PAD LEN. It is calculated as follows:
m 16 13 12
the remainder of the division of the polynomial S(m)x by the polynomial X + X + X +
∑
m=0
11 10 8 6 5 2
X + X + X + X + X + X + 1 is inverted and forms U (m), U (0) is the LSB.
L L
NOTE This polynomial is taken from IEC 60870-5-1 for format class FT3. It represents an optimum BCH-code with
Hamming distance 6 for block lengths ≤ 151 bits.

TS 613 34-5-4  IEC:2001(E)– 13 –
U(m) is then inserted into S(m):L
S(m + 24) = U(m ), m = 0.15L
5.2.4.6 PL
The payload fiel d cont ains th e PHY SDU of M byte s.
5.2.4.7 PAD
The padding field is used to ensure that the encoded PHY telegram exactly fits into one or
mult iple PHY blocks, see below.
5.2.4.8 PL CRC
The PL CRC field U(m), m = 0.15, contains the CRC checksum over the PL field. It is
PL
calculated as follows:
8M−1
16 13m
The remainder of the division of the polynomial S(m+)x by the polynomial X + X +
∑
m=0
12 11 108652
X + X + X + X + X + X + X + 1 is inverted and forms U(m ), U(0) is the L SB.
PL PL
NOTE This polynomial is taken from IEC 60870 -5 -1 for form at class FT3. It represents an optimum B CH-code with
Hamming distanc e 6 for bl ock lengths ≤ 15 1 bits.
U(m ) is then in se rted into S(m):PL
S(m + 8M + 40 + P) = U (m ), m = 0.15PL
5.2.4.9 FLUSH
The FLUSH field is used to flush the convolut iona l encoder, see be low.
5.2.5 Convolutional encoding
The uncoded PHY telegram S(m), m = 0.8M + P + 59 is convolutionally encoded to form the
encoded PHY telegram C(m), m = 0.16M + 2P + 119. The encoder is a rate 1/2 convolutional
encoder with constraint length G = 5 and code generator “polynomials” 10111 and 11001. At
the beginning, the encoder state is set to zero. The bit generated by the first code generator
is output first. T he use of the FLUSH field causes the encoder to be flushed, such that at the
end th e encoder is ag ain in state zero. The block diagram of the en coder is show n in figure 4.
++
E 2
ataD in
E 1
+++
IEC  990/01
Figur e 4 – Block diagram of encoder
oder outnc
oder outnc
– 14 –TS 61334-5-4  IEC:2001(E)
5.2.6 Segmentation and interleaving
The encoded PHY telegram is segmented into PHY blocks over which intra-block interleaving
is performed. The length of a PHY block, L, is a system parameter and has to be agreed upon
in order to achieve compatibility between suppliers.
Since the length of the encoded PHY telegram C(m) is 16M + 120 + 2P, it can be segmented
into Y PHY blocks of length L using P padding bits:
Y =  (16M + 120)/L 
P = (Y ⋅ L – (16M + 120))/2
The segmentation into blocks B(m,k) is done as follows:
B(m,k) = C(m  + k⋅ L), m = 0. L–1, k = 0.Y–1
The first index specifies the bit inside a block and the second index is the block number.
The block B(m,k) is transformed into a block V(m,k) using intra-block interleaving. The
interleaving depends on the number I of subcarriers and on channel conditions and has to be
agreed upon by the suppliers. Default is non-interleaving.
The resulting interleaved PHY telegram V(m,k) of size L⋅Y is mapped into Z(m,k) of size I⋅B,
where B is the number of symbols, B = Y ⋅L/I.
Z((m + k⋅L) mod I, (m + k⋅L) div I) = V(m,k), m = 0.L–1, k = 0.Y–1
Z(m,k) now contains the interleaved data to be transmitted. m = 0.I–1 denotes the carrier
number, k = 0.B–1 the symbol number.
5.2.7 Preamble
The synch preamble consists of the sequence X(k) (sync preamble).
X(0.24) = 1 1 1 1 1 0 1 0 1 1 1 0 0 1 1 0 1 0 0 0 0 0 0 0 1
The preamble is repeated in all subcarriers that are used in the preamble to form the burst
D(m,k):
D(m,k) = X(k),k = 0.22 ,  m = {0.N/2–1|r = 1}
m
5.2.8 Modulation
The preamble D(m,k) is transmitted using multicarrier differential phase shift keying with I
r
subcarriers. The unmodulated PHY telegram Z(m,k) is modulated as a multicarrier differential
phase shift keying (MC-DPSK) signal with I subcarriers and I bits per symbol.
First, the preamble D(m,k), m = {0.N/2–1|r = 1}, k = 0.22 is differentially encoded in the
m
time domain, yielding the differentially encoded preamble A(m,k), m = {0.N/2–1|r = 1}, k =
m
0.23:
A(m,0) = 1,  m = {0.N/2–1|r = 1}
m
A(m,k) = 2(D(m,k–1) ⊕ A(m,k–1))–1,   m = {0.N/2–1|r = 1}, k = 1.23
m
TS 61334-5-4  IEC:2001(E)– 15 –
where A(m,0) is the reference symbol for the preamble, and the symbol ⊕ represents
modulo-2 addition.
The unmodulated PHY telegram Z(m,k) is then differentially encoded:
A(m,24) = 1, m = {i }, k = 1.I
k
A(m,k) = 2(Z(m,k–25) ⊕ A(m,k–1))–1, k = 25.B + 24, m = {i }, k = 1.I
k
where A(m,24) is the reference symbol for the payload.
Now, A(m,k) is a ternary signal to be transmitted on frequency k at time n. A(m,k) has values
+1 for a binary ‘1’, –1 for a binary ‘0’ and 0 if no signal is to be transmitted.
Each symbol is modulated to form the signal s(t):
Preamble:
 t   t 
   
s(t) Am,  cos(2 f (i )t / N ) p t N  t 0.24N 1/N
= π ⋅ + ϕ ⋅ − = −
∑ 0 m rm 1
     
N N
   
   
m={m|r =1}
m
Payload:
For each symbol, generate a signal, using the data bits
I
 t   t 
   
Am,  cos(2πf ⋅ (i )t / N + ϕ ) ⋅ p t − N  t = 0.N − 1
0 m m 1
∑
     
N N
   
   
m=1
resulting in a vector of N = 64 samples. Copy of the last N samples of the 64-sample vector
CP
into an N -sample vector. Prepend this N -sample vector to the original 64-sample,
CP CP
resulting in an (N + 64)-sample symbol.
CP
p (t) is a rectangular pulse of length N:
1 t = 0.N − 1

p (t) =

0 otherwise

f = 288/N kHz. The bits shall be transmitted in increasing order of their numbering.
The preamble shall always be transmitted without cyclic prefix.
5.3 PHY services
5.3.1 PHY to MAC interface
5.3.1.1 PHY_DATA.request
5.3.1.1.1 Function
The PHY_DATA.request primitive is passed to the PHY layer entity to request that a PHY
PDU be sent to one or several remote PHY entity or entities using the PHY transmission
procedures.
– 16 –TS 61334-5-4  IEC:2001(E)
5.3.1.1.2 Structure
The semantics of this primitive are as follows:
PHY_DATA.request{
P_SDU}.
The P_SDU (PHY service data unit) parameter specifies the PHY service data unit to be
transmitted by the PHY layer entity. There is sufficient information associated with P_SDU for
the PHY sublayer entity to determine the length M of the data unit.
5.3.1.1.3 Use
The primitive is generated by the MACphy sublayer entity whenever data is to be transmitted
to a peer MAC entity or entities.
The receipt of this primitive will cause the PHY entity to perform all PHY specific actions (see
5.2.2) and pass the properly formed PDU to the mains attachment unit for transfer to the peer
PHY layer entity or entities.
5.3.1.2 PHY_DATA.confirm
5.3.1.2.1 Function
The PHY_DATA.confirm primitive has only local significance and provides an appropriate
response to a PHY_DATA.request primitive. The PHY_DATA.confirm primitive tells the MAC
sublayer entity whether the P_SDU of the previous PHY_DATA.request has been successfully
transmitted.
5.3.1.2.2 Structure
The semantics of this primitive are as follows:
PHY_DATA.confirm{
Result}.
The result parameter is used to pass status information back to the local requesting entity. It
is used to indicate the success or failure of the previous associated PHY_DATA.request.
5.3.1.2.3 Use
The primitive is generated in response to a PHY_DATA.request.
It is assumed that the MAC sublayer has sufficient information to associate the confirm with
the corresponding request.
5.3.1.3 PHY_DATA.indication
5.3.1.3.1 Function
This primitive defines the transfer of data from the PHY layer entity to the MAC sublayer
entity.
5.3.1.3.2 Structure
The semantics of this primitive are as follows:
PHY_DATA.indication{
P_SDU}.
The P_SDU parameter specifies the PHY service data unit as received by the local PHY
sublayer entity.
TS 61334-5-4  IEC:2001(E)– 17 –
5.3.1.3.3 Use
The PHY_DATA.indication is passed from the PHY layer entity to the MAC sublayer entity to
indicate the arrival of a valid PDU.
6 MAC sublayer protocol specification
6.1 Overview
6.1.1 MAC communication network architecture
The communication network is subdivided into domains. Each of these domains is organized
around a master station. Slave stations in a domain are registered to that master station.
Communication with a different master station is supported for test and network management.
Medium access within a domain is controlled by one station at a time. This station is called
the 'initiator'.
Communication always involves the current 'initiator'. Direct communication between any two
stations, of which neither is an 'initiator', is not supported.
6.1.2 Features of the MAC sublayer
The MAC sublayer exhibits the following features:
− both confirmed and unconfirmed transmission of PDUs;
− initiator controlled medium access;
− support of varying processing times in remote stations using different MAC service
classes;
− multi-hop transmission (routing repetitions) transparent to MAC users;
− transmission error detecting capabilities for transmission failures on any hop level through
cascaded timers.
6.2 Transmission procedures
The MAC sublayer provides different service classes. Dependent on the requested service
class, different transmission procedures are used.
MAC service class 0 uses the postponed confirmation scheme (figure 5): the MAC sublayer
generates the confirmation at the end of the transmission by the physical layer.
MAC service classes 1 and 2 use round-trip delayed confirmation (figure 6): the MAC sublayer
starts at a timer as long as the round trip delay needed for the remote station to transmit an
LLC frame back. MAC service class 1 sets the timer value to T , MAC service class 2 sets
delay1
the timer value to T (see 6.9).
delay2
– 18 –TS 613 34-5-4  IEC:2001(E)
Init iatorRepeat erNon-in it iator
MA_DATA.request
MA_DATA.indication
MA_DATA.confirm
IEC  991/01
Figur e 5 – MAC transmission using MAC service class 0 (post poned co nfirmation)
Init iatorRepeat erNon-in it iator
MA_DATA.request
MA_DATA.indication
Maximum dur ation
depends on
MAC service cl ass
MA_DATA.request
MA_DATA.confirm
MA_DATA.confirm
MA_DATA.indication
IEC  992/01
Figur e 6 – MAC transmission using MAC service class 1 or 2 (r ound-tr ip delayed c onfirmation)
6.3 MAC services
6.3.1 MAC to LLC interf ace
6.3.1.1 MA_DATA.request
6.3.1.1.1 Function
The MA_DATA.request primitive is passed to the MACrore sublayer entity to request that a
MAC SDU be sent to one or several remote MACrore entity or entities using the MACrore
tran smission procedures.
6.3.1.1.2 Structure
The semant ics of this pr im itive are as follows:
MA_DAT A.reques t{
Destin ation_addr ess,
M_SDU,
Service_class}.
TS 61334-5-4  IEC:2001(E)– 19 –
The Destination_address parameter specifies an individual or group MAC address.
NOTE 1 A non-initiator MAC may only use an individual initiator MAC address as Destination_address.
The M_SDU (MAC service data unit) parameter specifies the MAC service data unit to be
transmitted by the MAC sublayer entity. There is sufficient information associated with
M_SDU for the MACrore sublayer entity to determine the length of the data unit.
The Service_class parameter specifies the type of service that the MACrore sublayer entity
has to use to transmit the M_SDU. The parameter can take the following values which are
associated with a certain MAC confirmation scheme:
0: 'Postponed Confirmation, no reply from remote': The MAC sublayer postpones the confirmation until
the complete transmission, including repetition steps, is carried out. Service class '0' is intended to
be used with PDUs where no answer from the remote station(s) is allowed.
1,2: 'Round-trip delayed Confirmation 1,2': After transmission of a PDU, the MAC sublayer starts a timer
with a value that takes the transmission time to the remote station (including processing time in
intermediate repeaters), processing time in the remote station and transmission time of a reply (with
a limited size) into account. After reception of a PDU from the remote MAC entity, the timer is
stopped. At expiration of the timer, a MA_DATA.confirm with bad transmission status is generated.
Service_class 1 and service_class 2 differ by the allowed processing time and the maximum size of
the reply PDU.
NOTE 2 The source MAC address is not specified since it is a local parameter that the MAC sublayer will fill in
itself with regard to the protocol rules.
6.3.1.1.3 Use
The primitive is generated by the LLC sublayer entity whenever data is to be transmitted to a
peer LLC entity or entities.
The receipt of this primitive will cause the MAC entity to prepend all MAC specific fields (cf.
MAC PDU description below) and pass the properly formed PDU to the lower layers of the
protocol for transfer to the peer MAC sublayer entity or entities.
6.3.1.2 MA_DATA.confirm
6.3.1.2.1 Function
The MA_DATA.confirm primitive has only local significance and provides an appropriate
response to a MA_DATA.request primitive. The MA_DATA.confirm primitive tells the LLC
sublayer entity whether the M_SDU of the previous MA_DATA.request could be transmitted.
6.3.1.2.2 Structure
The semantics of this primitive are as follows:
MA_DATA.confirm{
Transmission_status}.
The Transmission_status parameter is used to pass status information back to the local
requesting entity. It is used to indicate the
...