ETSI TS 103 323 V1.1.1 (2015-03)

PowerLine Telecommunications (PLT); Spectral Management of neighbouring PLT networks based on Dynamic Spectral Management (DSM)

DTS/PLT-00045

General Information

• Status: Published
• Publication Date: 16-Mar-2015
• Technical Committee: PLT - Powerline Telecommunications
• Current Stage: 12 - Completion
• Due Date: 18-Mar-2015
• Completion Date: 17-Mar-2015

Standards Content (Sample)

ETSI TS 103 323 V1.1.1 (2015-03)






TECHNICAL SPECIFICATION
PowerLine Telecommunications (PLT);
Spectral Management of neighbouring PLT networks based on
Dynamic Spectral Management (DSM)

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2 ETSI TS 103 323 V1.1.1 (2015-03)



Reference
DTS/PLT-00045
Keywords
network, powerline
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3 ETSI TS 103 323 V1.1.1 (2015-03)
Contents
Intellectual Property Rights . 4
Foreword . 4
Executive summary . 4
Modal verbs terminology . 4
Introduction . 4
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Abbreviations . 6
4 Configuration of the PLT network in customer premises . 7
5 Solution based on iterative bit-loading . 8
6 Recommendation based on DSM for NN PLT coexistence in a MDU . 13
History . 14

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4 ETSI TS 103 323 V1.1.1 (2015-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Powerline Telecommunications
(PLT).
Executive summary
Addressing the coexistence problems of PLT neighbourhood networks operating in customer environments, the present
document describes spectral management for OFDM based transceivers for minimizing the impact like the drop of
bitrate.
The solution is based on spectral management reducing the power level of interfering PLT carriers on PLT
neighbourhood carriers and spreading data on remaining PLT carriers. The Dynamic Spectral Management (DSM)
processing implemented in PLT modems is suitable for second generation PLT modems operating up to 80 MHz.
The present document propose a new approach for solving the interference caused by neighbouring networks, when at
least two customers are using PLT modems on powerline.
It is proposed to adopt this approach, so that PLT home networking transceivers are equipped with Dynamic Spectral
Management (DSM) in the domain master.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The majority of the population in the world live in multi-dwelling unit (MDU) buildings. The need for sharing high-
speed networking within these often closely spaced units has resulted in an increase in the use of High Frequency (HF)
generated by powerline telecommunications (PLT).
The PLT networks within a given MDU will be in close proximity to each other, and connect to the same wiring, so the
signals will be detectable on adjacent networks. This may appear as a source of interference, which can limit the PLT
throughputs.
This is a common problem of all networking technology whose signals are not physically constrained. Neighbouring
Networks (NN) interference occurs when signals transmitted over one home network propagate to neighbouring
networks.
For PLT, signals can transfer to other PLT networks through inductive propagation or due to low attenuation when the
networks share common feeder lines as the number of PLT deployed systems increases.
The present document describes a technique based on DSM to address this problem.
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5 ETSI TS 103 323 V1.1.1 (2015-03)
Dynamic Spectrum management (DSM) has been recognized as a key technology for tackling multi-user crosstalk
interference for DSL broadband access.
The present document proposes a method based on dynamic spectral management multi-user signals from several PLT
modems operating in neighbouring networks. Inside this network the domain master modem have the capacity to handle
complex DSM operations.
The solution, described in the present document, is based on minimization of the interference by coordination at
Physical layer level using dynamic spectral management approach.
Solving this interference at signal level is important for the next generation of PLT modems and in large scale
deployments of next generation home networks with peaceable relationship with users in a vicinity.
DSM methods can avoid unnecessary impoliteness between neighbours using PLT modems if their Domain Master
modems integrate efficient carrier management using DSM.
PLT networks communicate using high frequency signals transmitted over a residence's mains power wiring. The signal
power is generally sufficient to allow communication between all the in-home power sockets; however, this means the
signals can also propagate beyond the intended residence.
Many PLT technologies transmit at the highest signal strength allowed, to overcome noise and ensure they can pass data
at the maximum rate within their own network; however, this increases the problem for their neighbours. The number of
neighbouring networks affected depends on the PLT signal strength, topology of the MDU wiring, and the impedance
between networks. It is quite common for PLT networks more than one floor away to detect signals from another PLT
network.
This interference occurs when a line in the electrical network is situated close to a line in this other network. This is
because, as these high-rate technologies use at least partially the same reserved frequency band, and the same data
coding method by distribution over carrier frequencies, in this case OFDM, when a line in the electrical network is
situated in the vicinity of a line in this other network, the transmission performance of the transmission channel of each
of the two networks degrades, causing in particular losses of transmission rate on these two networks.
This interference is amplified when the modems in the two local networks are supplied by the same electrical source
since, in this case, coupling by conduction between the modems occurs.
The use of the electrical network and another network for distributing the services of a triple-play offer therefore poses
the problem of interference between a powerline signal that is transmitted between modems on an electrical network
and a signal that is transmitted on another network, which may be an electrical network possibly distinct from the first.
More precisely, this iterative method consists, at each iteration, of optimizing the transmission rate of the transmission
channel on the line and the transmission power level of the signal transmitted on this channel, considering the
interference on the other lines in this network as noise and subject to a given spectral density profile.

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6 ETSI TS 103 323 V1.1.1 (2015-03)
1 Scope
The present document defines requirements on coexistence between two PLT transceivers operating in the same
frequency band and on same electrical cables on different neighbouring networks.
The present document includes a solution based on signal processing algorithms for minimizing of the interferences
caused by one PLT on other PLT network based on spectral management
It is assumed the PLT network is based on a master and slaves modems.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] W. Yu et al: "An Adaptive Multiuser Power Control Algorithm for VDSL", GLOBECOM01,
vol. 1, 2001.
[i.2] ETSI TR 102 269: "PowerLine Telecommunications (PLT); Hidden Node review and statistical
analysis".
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BF Frequency Band
DM1 Domain Master for user 1
DM2 Domain Master for user 2
DSL Digital Subscriber Line
DSM Dynamic Spectrum Management
HF High Frequency
MAC Medium Access Controller (Layer 2)
MCPL PLT Modem Courant porteur en Ligne
MDU Multi-Dwelling Unit
MIMO Multiple Input Multiple Output
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7 ETSI TS 103 323 V1.1.1 (2015-03)
NN Neighbouring Networks (PLT)
OFDM Orthogonal Frequency Division Multiplexing (Multi-carrier transmission)
PHY Physical Layer /transmission (Layer 1)
PLT PowerLine Telecommunication
PSD Power spectral density
R Electrical Network 1
1
R Electrical Network 2
2
S PLT signal for user 1
1
S PLT signal for user 2
2
SNR(F) Signal to Noise Ratio at frequency F
VDSL Very high speed Digital Subscriber Line (15 MHz)
VDSL2 Second generation of VDSL (30 MHz)
4 Configuration of the PLT network in customer
premises
It is assumed that the Service Provider has installed a network using the same PLT technology in each user unit. These
networks will interfere with one another to an extent dependent on their relative physical location, potential for signal
propagation between networks, and the electrical path the signals can take between networks.
The configuration of the PLT networks in close proximity to apartments, which may or may not be the case, depending
on MDU wiring rules for each country.
The PLT signals can cross over between networks over the in-building wiring. Typically, there is 20 to 40 dB
attenuation between networks due to the circuit breakers, meters, cable distances and topology; however, this value will
vary between individual PLT nodes and between PLT networks.
According to ETSI TR 102 269 [i.2], the median attenuation @ 15 MHz between sockets in the same flat is 40 dB,
while median attenuation @ 15 MHz between in different flats is 60 dB. Roughly, this would add 20 dB for median
inter unit attenuation.
Each network in the MDU building experiences its own set of interference, distinct from that of other networks.
Therefore, each network has its own NN PLT networks mitigation needs. The interference a PLT network experiences
is known as the network's interference pattern. Further, each node in each network has its own node interference pattern.
NN interference can be time varying with respect to amplitude or even presence.
These nodes not only experience NN interference when they are powered up, they also change the interference pattern
for all networks and nodes that detect their signals.
This interference occurs when a line in the electrical network is situated close to a line in this other network. This is
because, as these high-rate technologies use at least partially the same reserved frequency band, and the same data
coding method by distribution over carrier frequencies.
However, as the number of PLT networks deployed in the building increases, neighbouring network interference
increases and service deteriorates, with resultant service calls.
The local network's nodes detect the NN signals as noise, thus raising the noise floor and reducing the signal to noise
ratio (SNR) of the local nodes, effecting their throughput and ability to overcome other noise they encounter.

Figure 1: Illustration of two electrical networks R1 and R2 interfering in a MDU
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8 ETSI TS 103 323 V1.1.1 (2015-03)
As stated previously, PLT networks interference is deemed to be high when another PLT signal is strong enough to be
detected by a local network node as a valid PLT signal and that this signal's power level is enough to overcome local
PLT signals.
When signals are at this level, the interfered networks' ability to pass data deteriorates and they shall use some form of
mutual mitigation, or they will operate with a significantly lower throughput or even lose connectivity.
The newly introduced Multiple Input, Multiple Output (MIMO) PLT modems is a means of having multiple transmit
paths and receive paths when 3-wire cabling and sockets are used in residences. MIMO may actually exacerbate NN
interference in that MIMO-PLT may enable PLT signals from one unit to reach another unit with a stronger overall
signal.
The power leads have higher attenuation than other lead types due to transiting breakers and meters. While this
interference MIMO-PLT pattern is similar to SISO-PLT as MIMO signal paths between living units.
With PLT signal transmission over the power grid network, there is signal attenuation due to the breakers and meters.
This attenuation, in most cases, however, it is not enough to eliminate inter-unit network interference.
5 Solution based on iterative bit-loading
The present clause describes a method for reducing interference between a signals transmitted by power line modem
networks within the neighbourhood vicinity. In general terms, the present document describe a method of reducing
interference between a powerline signal S transmitted between modems MCPL1 in an electrical network R and a
1 1
signal S transmitted between modems MCPL2 in another network R . The signals S and S are coded by the
2 2 1 2
distri
...