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Chapter 2 System Overview
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2.1
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2.1.1
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Network Reference Block Diagram
System Reference Model
At the highest level of abstraction, the HomePlug GREEN PHY system consists of the
functional blocks shown in Figure 2-1. Note that the basic reference model is identical to
HomePlug AV.
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Figure 2-1: System Block Diagram
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On the transmit side:
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
The PHY layer performs error-control correction, mapping into OFDM Symbols, and
generation of time-domain waveforms.
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
The MAC determines the correct position of transmission, formats data frames into
fixed-length entities for transmission on the channel and ensures timely and error-free
delivery through Automatic Repeat Request (ARQ).
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
The Convergence layer performs bridging, classification of traffic into Connections, and
data delivery smoothing functions.
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The receive side performs the corresponding functions, in reverse.
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defined.
Copyright © 2010,2012, HomePlug Powerline Alliance, Inc. All rights reserved.
Subject To the Terms and Conditions of the HomePlug Limited Copyright License
Agreement or the HomePlug Sponsor Members and Associate Members Agreements
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2.1.2
Protocol Layer Diagram
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3
Figure 2-2 shows the protocol entities defined in this specification interface as they relate to
each other.
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Protocol entities that get directly involved in the transfer of user payload make up the Data
Plane of the protocol stack. Protocol entities that are involved in creating, managing and
terminating the flow of data make up the Control Plane. Protocol entities communicate with
each other through Service Access Points (SAPs), i.e., well-defined interfaces described
through primitives, which can be thought of as precursors of Application Programming
Interfaces (APIs) between blocks that implement the protocol entities.
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The specification has chosen to define the Control Plane as a single monolithic entity, called
the “Connection Manager” (CM), rather than defining interfaces and primitives within the
Control Plane. In each logical network (refer to Section 2.2.2) one station, called the Central
Coordinator (CCo) (refer to Error! Reference source not found.), is responsible for setting
up and maintaining the logical network, managing the communication resource on the wire,
and coordinating with neighbor networks that use the same wire resource (refer to Error!
Reference source not found.). The CCo may be viewed as a network-wide control plane
entity. There is precisely one active CCo per network.
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Figure 2-2: Protocol Layer Architecture
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2.2
2
2.2.1
Network Concepts
Physical Network
The Physical Network (PhyNet) of a given STA (station) is the set of STAs that can physically
communicate with the STA  at least at the level of Frame Control (FC) and ROBO mode
(i.e., it is the set of STAs seen by the PHY). All stations in a PhyNet have the potential to
interfere with each other, but they also have the capability to minimize the mutual
interference through coordination (refer to Error! Reference source not found.).
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Note: A PhyNet is relative to a given STA, and it is possible that the PhyNets of physically
close-by STAs are distinct. Figure 2-3 shows three examples of PhyNets, where the lines
indicate ability to communicate on the PHY level. It is assumed that all STAs that can
communicate with each of the depicted STAs in Figure 2-3 are shown in the figure. The
PhyNets of all STAs in the three examples are summarized in Table 2-1. Note that:
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
In the first example (Figure 2-3a,) all stations can communicate with each other and the
PhyNet of all stations is the same set {A,B,C,D,CCo}.
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
In the third example (Figure 2-3c), the PhyNet of D does not include the CCo.
Furthermore, STA D is not in the PhyNet of the CCo, making D a “hidden station.” A
hidden STA is a station that does not belong to the PhyNet of the CCo, but belongs to the
PhyNet of at least one STA that is in the PhyNet of the CCo.
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Table 2-1: PhyNets in Figure 2-3
Physical Networks (PhyNets) in …
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21
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2.2.2
STA
Figure 2-3a
Figure 2-3b
Figure 2-3c
A
{A,B,C,D,CCo1}
{A,B,CCo1}
{A,B,CCo1}
B
{A,B,C,D,CCo1}
{A,B,CCo1}
{A,B,CCo1}
C
{A,B,C,D,CCo1}
{C,D,CCo2}
{C,D,CCo1}
D
{A,B,C,D,CCo1}
{C,D,CCo2}
{C,D}
CCo1
{A,B,C,D,CCo1}
{A,B,CCo1,CCo2}
{A,B,C,CCo1}
CCo2
N/A
{C,D,CCo1,CCo2}
N/A
Logical Networks and SubAVLNs
An AV In-Home Logical Network (AVLN) is the set of STAs, typically used in a home
environment, that possess the same Network Identifier (NID) and NMK known by the CCo
(refer to Section Error! Reference source not found.). An AVLN typically will have a single
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Network Membership Key (NMK) (refer to Error! Reference source not found.), but may
have more than one NMK for secure distribution of different Network Encryption Keys (NEKs –
refer to Section Error! Reference source not found.). If the CCo elects to deploy multiple
NEKs (possibly using multiple NMKs), several logical subnetworks of the AVLN are formed.
These are called sub-AVLNs. Coordination, clock reference, and scheduling are performed on
the basis of an AVLN. Cryptographic isolation is provided at the level of the sub-AVLN.
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An AVLN is managed by a single STA called the Central Coordinator (CCo). Broadband Access
over Power Lines (BPL) is beyond the scope of this specification, although Error! Reference
source not found. addresses the coexistence between AVLNs and BPL networks.
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Note: An AVLN can coincide with the PhyNet of one or more STAs (as in Figure 2-3a) or be a
subset of the PhyNet of a STA (as AVLN_1 in Figure 2-3b relative to the PhyNet of CCo1), or
span the PhyNets of multiple STAs (as in Figure 2-3c). AVLN_1 and AVLN_2 in Figure 2-3b can
form a pair of Neighbor Networks (refer to Error! Reference source not found.).
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2.2.3
Communication Inside an AVLN
Two stations belonging to an AVLN will be able to communicate with each other if they
belong to each other’s PhyNet (see Figure 2-3). Note that it is possible, but not likely in
typical deployments, that a broadcast transmission inside an AVLN is not received by all the
stations of the AVLN. For example, in Figure 2-3c, broadcast transmissions from STA A will
not be heard by stations C or D. Further, broadcast transmissions from CCo1 will not be
heard by STA D, creating the need for STA C to act as a Proxy Coordinator (refer to Section
Error! Reference source not found.) to manage STA D as part of the AVLN.
AVLN
CCo1
A
C
B
D
(a)
AVLN_1
CCo1
CCo2
AVLN_2
A
C
D
B
(b)
AVLN
CCo1
A
C
B
D
(c)
1
2
Figure 2-3: Examples of PhyNets and AVLNs
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2.3
Station Roles
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Each node in an AV Logical Network must have a minimum functionality, as described in the
rest of this specification. Such a node is referred to as an AV Station, GREEN PHY Station, or
simply “Station” (STA). In addition to the minimum functionality, STAs may also implement
optional features.
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Each STA in an AVLN shall be capable of managing the network, and as a minimum is
responsible for:
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
Association and authentication of new STAs
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
Provisioning of Terminal Equipment Identifiers
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
CSMA-Only mode of operation and Passive Coordination of medium allocation with
neighboring networks
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Such a STA is called a Level-0 Central Coordinator (CCo) station (i.e., CCo without QoS
support).
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A STA that, in addition to the above functions, also provides:
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
Uncoordinated mode of operation
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
Provisioning of Global Link Identifiers, Admission control, and TDMA Scheduling for
Global Links
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is called a Level-1 CCo station. Level-1 CCos do not support Coordinated Mode.
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A STA that, in addition to the above functions, also provides:
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
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is called a Level-2 CCo station. The designation of Level-3 CCo is reserved for future CCos
with advanced capabilities. At minimum, all stations are required to implement Level-0 CCo
functionality. A station implementing HomePlug AV may support Level-1 or Level-2 CCo
functionality. A station implementing only GREEN PHY is only required to implement Level-0
CCo functionality. More detailed description about CCo capabilities can be found in Section
Error! Reference source not found..
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The abbreviation CCo may refer to any of these types of Central Coordinator, and in the
absence of further qualification, its meaning should be clear from the context. CCos can
either be preconfigured as such or be automatically selected using the procedures of Error!
Reference source not found.. Only one STA in an AVLN can play the role of Central
Coordinator at a time. An AVLN with a Level-x CCo is also referred to as Level-x AVLN
throughout the specification.
Coordinated Mode-based coordination with CCos of neighboring networks (NCCos)
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One or more of the non-CCo stations of an AVLN may play a role in managing hidden STAs.
Such STAs are called Proxy Coordinators (PCo) (refer to Error! Reference source not
found.). The PCo functionality is optional.
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One or more stations in the AVLN may act as bridges to other networks. The bridge is
responsible for routing traffic between the AVLN and the other network based on a list of
MAC addresses of devices it is bridging for. The bridge is also responsible for providing this
list to other stations in the AVLN so other stations can efficiently deliver traffic within the
AVLN using unicast transmissions.
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2.4
This section provides an overview of security goals, controls, and issues as perceived during
development of this specification. This section and all its subsections are informative.
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Security Overview
2.4.1
Security Goals and Constraints
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An AVLN (or sub-AVLN) should be equivalent to a Category 5 wired network as much as
practical. Specifically:
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
Network stations (STAs) should not be allowed to join a user’s AV Logical Network
(AVLN) unless the user is confident that the station is the equipment he wants to add.
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
STAs within the same AVLN are assumed to be trustworthy (i.e., they do not perform
hostile actions or divulge keys deliberately).
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
STAs within a sub-AVLN should be able to communicate confidentially (message contents
should not be exposed to stations outside the sub-AVLN).
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
STAs within an AVLN should have confidence in the integrity of the messages they
receive (i.e., they were neither damaged nor deliberately changed, nor are they replays
or forgeries).
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
It should be hard for a different AVLN to “capture” a STA, but it should be easy for a
user to reclaim a device he owns that was “captured” by another network.
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
A user should be able to reset a device and give or sell it to another user.
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2.4.2
Threat Model
We assume that a neighbor may be able to eavesdrop on transmissions within a residence,
and may also be able to send transmissions to stations within that residence, without the
knowledge of the users in that residence. We try to protect the system against
knowledgeable attackers with reasonable resources, but not against well-funded attackers.
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As a point of reference, one may assume that the attacker has access to a handful (say 10)
of the fastest commercially available PCs today.
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We also assume that for most situations (particularly in regard to Simple Connect Security
Level), the attacker will not have access to specialized hardware for signal processing or
MPDU reception, other than commercially available HomePlug AV or HomePlug GREEN PHY
chips.
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All hosts that have access to the network as a member of the AVLN or through a bridge that
has joined the AVLN are considered to be benign.
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2.5
HomePlug GREEN PHY Operation Under Various Regulatory Jurisdictions
The frequency bands and the transmit power that can be used by power line communication
systems can change based on the regulatory jurisdiction. As with HomePlug AV, the GREEN
PHY system uses the Tone Mask (refer to Section Error! Reference source not found.) and
Amplitude Map (refer to Section Error! Reference source not found.) to enable
modification of the transmit power spectrum to comply with regulatory constraints.
HomePlug GREEN PHY currently defines the Tone Mask and Amplitude Map for operation
within North America. Tone Masks and Amplitude Maps for other regulatory jurisdictions will
be set by HomePlug as regulations for those regions become clear.
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2.6
Parameter Specifications
Table 2-2 lists the HomePlug AV parameter specifications.
Table 2-2: HomePlug AV Parameter Specifications
Parameter
Value
Allocation Interframe Spacing (AIFS)
30 sec min.
AllocationTimeUnit
10.24 sec
Section Reference
5.6
Error! Reference
source not found.
Error! Reference
source not found.
Error! Reference
source not found.
Error! Reference
source not found.
Beacon To Beacon Interframe Spacing (B2BIFS)
90 sec ±0.5 sec
Error! Reference
source not found.
Table 2-2: HomePlug AV Parameter Specifications
Parameter
Value
Section Reference
Burst Interframe Spacing (BIFS)
20 ±0.5 sec
Error! Reference
source not found.
CCo_Failure_Time
≥ 10 Beacon Periods
Error! Reference
source not found.
CFPI_EIFS
250 sec
Error! Reference
source not found.
CIFS
35.84 ±0.5 sec
(from start of extended Symbol(s) until start
of PRS0)
Error! Reference
source not found.
(HomePlug 1.0.1
specification)
CIFS_AV
100 ±0.5 sec
Error! Reference
source not found.
Contention-Free Interframe Spacing (CFIFS_AV)
30 sec min. to 140 sec max.
Error! Reference
source not found.
CTS-MPDU Gap (CMG)
120 ±0.5 sec
Error! Reference
source not found.
Default Maximum MSDU Size
1522 octets
Error! Reference
source not found.
Discovered_List_Expire_Time
3 to 5 minutes
Error! Reference
source not found.
EIFS_AV
2920.64 ±5.0 sec
Error! Reference
source not found.
Extended Interframe Space (EIFS)
1695.0 ±5.0 sec
Error! Reference
source not found.
FAIL_WAIT
1 sec  FAIL_WAIT  5 sec
Error! Reference
source not found.
FHM_TimeOut
 1 sec
Error! Reference
source not found.
FragMMI_ReassemblyTimeOut
 1 sec
Error! Reference
source not found.
GI (Guard Interval)
5.56 sec, 7.56 sec, 47.12 sec
Error! Reference
source not found.
HP1_FC_Thresh
2
Error! Reference
source not found.
HP1_FC_Thresh_Interval
1 second
Error! Reference
source not found.
HP1D_ReportDuration
1 sec
Error! Reference
source not found.
Table 2-2: HomePlug AV Parameter Specifications
Parameter
Value
Section Reference
IDLE_BEACON_SLOT_TIMEOUT
 10 * Beacon Period
Error! Reference
source not found.
LBDAT_EXPIRE_TIME
 100 sec
Error! Reference
source not found.
LinkStatusTimeout
 MaxDiscoverPeriod
Error! Reference
source not found.
MaxBeaconSlot
8
Error! Reference
source not found.
MAX_BIR_TIME
100 sec
Error! Reference
source not found.
Max_Missed_Beacon
2
Error! Reference
source not found.
MaxFL_AV
2501.12 sec ≤ MaxFL_AV ≤ 5241.6 sec
Maximum Beacon scan time (MaxScanTime)
4 sec
Error! Reference
source not found.
Maximum CCo Beacon Scan Time
(MaxCCoScanTime)
2 sec
Error! Reference
source not found.
Maximum Discover Period (MaxDiscoverPeriod)
10 seconds
Error! Reference
source not found.
MaxNoBeacon
>10
Error! Reference
source not found.
Max_Reassembly_Timer (for Connectionless
traffic)
5 ms  Max_TX_Timer  1 s
Error! Reference
source not found.
Max_TEK_Lifetime
120 seconds
Error! Reference
source not found.
MAX_TONE_MAPS
7
Error! Reference
source not found.
MMEResponse_WaitTime
2 seconds
Error! Reference
source not found.
Max_TX_Timer (for Connectionless traffic)
5 ms  Max_TX_Timer  1 s
Error! Reference
source not found.
MIN_BIR_TIME
100 ms
Error! Reference
source not found.
MinCSMARegion
1500 sec
Error! Reference
source not found.
Minimum Beacon scan time (MinScanTime)
2 sec
Error! Reference
source not found.
11.5.10.1
Table 2-2: HomePlug AV Parameter Specifications
Parameter
Value
Section Reference
Minimum CCo Beacon Scan time
(MinCCoScanTime)
1 sec
Error! Reference
source not found.
Priority Resolution Slot (PRS)
35.84 ±0.5 sec
Error! Reference
source not found.
(HomePlug 1.0.1
specification)
RBAT_EXPIRE_TIME
> 100 sec
Error! Reference
source not found.
RIFS_AV
30 sec to 160 sec
Error! Reference
source not found.
RIFS_AV_default
140 ±0.5 sec
Error! Reference
source not found.
RIFS_hp1
26.0 ±0.5 sec
Error! Reference
source not found.
(HomePlug 1.0.1
specification)
RTS/CTS Gap (RCG)
120 ±0.5 sec
Error! Reference
source not found.
SHM_TimeOut
> 1 sec
Error! Reference
source not found.
Slot Time
35.84 ±0.5 sec
Error! Reference
source not found.
(HomePlug 1.0.1
specification)
Unassociated STA Advertisement Interval (USAI)
1 sec
Error! Reference
source not found.
Table 2-3: HomePlug GREEN PHY parameters differing from HomePlug AV 1.1
Parameter
1
Value
Section Reference
MAX_TONE_MAPS
0
Max_Route_Update_Time
30 minutes
5.10.1.1
Min_Route_Update_Time
5 minutes
5.10.1.1
RDR_Significant_Change
10 percent
5.10.1.1
Error! Reference
source not found..3