broadband over power

8/2/2019 Broadband Over Power

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2007 Bechtel Corporation. All rights reserved. 1

INTRODUCTION

There are two basic means of providingcommunications services: wireless or wireline.On the wireless side, the main hurdle is

scarceness of radio frequency (RF) spectrum and

the associated huge cost. In the US, spectrum is

viewed as a scarce national resource, closely

guarded by the Federal Communications

Commission (FCC). Based on the FCCs personal

communications services (PCS) auctions, the

median value of 1 MHz of spectrum per pop was

around US$1.68 [1]. Simple math shows that

a bare minimum of 10 MHz of spectrum(a pair of 5 MHz, enough for only one channel

of current frequency division duplex [FDD]

technologies such as universal mobile

telecommunications system [UMTS]) that

covers 300 million US pops could cost close to

US$5 billion! And there is the cost of deploying

the network. On top of this, there are the ongoing

site rental or lease fees, which, on a nationwide

basis, could translate to hundreds of millions

or even billions of dollars annually. These factorsmake widespread usage of wireless broadband

relatively difficult and expensive!

On the wireline side, there are currently two

means of providing broadband services: digital

subscriber line (DSL) through telephone company

telephone lines, and cable modem through cable

company coaxial cable lines. Now, with the

advent of broadband over power lines (BPL or

BoPL), a third wired option is emerging that uses

electric utility power lines. Power lines are

attractive for communications purposes because

they have an omnipresence that reaches mosthomes and businesses, even in the most rural

areas. This ubiquity implies a possible reduction

in both time and cost for broadband deployment

In this sense, power lines, like RF spectrum, can

be considered a very valuable national resource,

or even a national treasure. And, of course, there

is the inside-home power line wiring that can

literally turn every outlet plug into a broadband

communications access port.

BROADBAND OVER POWER LINES (BPL)

AbstractThe Internets proliferation has focused attention on the importance of providing widespreadaccess to broadband services. Many studies show that such access can have profound positive socioeconomicimpacts. Currently, however, broadband access is available to relatively few people worldwide. Broadbandaccess has traditionally been provided via either DSL or cable. More recently, wireless and satellite broadbandaccess has also gained significant momentum. Now, a thirdwiredoption is emerging: broadband over

power lines (BPL).

Power lines, however, were designed to deliver power, not communications, which poses three main hurdles forBPL. First, the variation in power line channel characteristics and performance over time and location must be

appropriately considered. Second, measures must be put into place to ensure that BPL does not causeinterference for the existing rightful owners of the spectrum. Third, the regulatory issues accompanying anynew technology must be addressed.

As these hurdles are overcome, as standards mature, and as inexpensive standards-based equipment becomesmore widely available, the concerns about the risks of BPL investment and deployment will gradually diminishThen, the right business and deployment models will enable BPL to capture a significant portion of the thrivingbroadband market.

Key Wordsaccess BPL, BPL, broadband over power lines, capacity, channel characteristics, coupler,extractor, FCC, injector, in-house BPL, interference, low voltage (LV) line, medium voltage (MV) line, noise,NTIA, Part 15, PLC, power line communications, repeater, Subpart G, transformer bypass

Issue Date: January 2007

Lee Lushbaugh

[email protected]

S. RasoulSafavian, PhD

[email protected]


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Bechtel Telecommunications Technical Journal2

ABBREVIATIONS, ACRONYMS, AND TERMS

AC alternating current

AMR automated meter reading

AP access point

ARRL American Radio Relay League

AWGN additive white gaussian noise

BoPL broadband over power linesBPL broadband over power lines

CALEA Communications Assistancefor Law Enforcement Act

CENELEC European Committee forElectrotechnical Standardization

CFR Code of Federal Regulations(47 CFR addressestelecommunications)

CPE consumer premises equipment

CSMA/CA carrier sensing multipleaccess/collision avoidance

DAS distributed antenna system

dBm power in decibels withreference to 1 milliwatt

DSL digital subscriber line

EHV extremely high voltage(> 300 kV)

EM electromagnetic

EMC EM compatibility

EMI EM interference

ETSI European Telecommunications

Standards InstituteFCC Federal Communications

Commission

FDD frequency division duplex

FTTH fiber to the home

GDP gross domestic product

HDTV high definition television

HF high frequency (3 to 30 MHz)

HV high voltage (36 to 300 kV)

IEEE Institute of Electrical andElectronics Engineers

ISP Internet service provider

LAN local area network

LF low frequency

LV low voltage (< 1 kV)

MAC medium access control

MO&O Memorandum ofOpinion & Order (FCC)

MTL multiconductor transmissionline

MV medium voltage (1 to 36 kV)

NEC numerical EM code

NMS network management system

NOI Notice of Inquiry

NPRM Notice of Proposed RuleMaking (FCC)

NTIA National Telecommunicationsand Information Administration

OFDM orthogonal frequency divisionmultiplexing

OPERA Open PLC European ResearchAlliance

OSS operations support system

PC personal computer

PCS personal communications

services

PL power line

PLC power line communications

POP point of presence

PSTN public switched telephonenetwork

QoS quality of service

R&D research and development

R&O Report & Order (FCC)

RF radio frequency

RMS root mean square

ROI return on investment

SCADA supervisory control and dataacquisition

SW shortwave (5.9 to 26.1 MHz)

UHF ultra high frequency

UMTS universal mobiletelecommunications system

UPA Universal PowerlineAssociation

USAC Universal Service

Administrative Company

USF Universal Service Fund

UTC United Telecom Council

VHF very high frequency(30 to 300 MHz)

VoIP voice over Internet Protocol


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Considering that broadband penetration is

currently less than 4 percent globally, the huge

growth potential for the broadband market is

obvious. BPL could provide a quick and attractive

solution. Of course, successful BPL deployment

requires not only a solid technical performance

and field trial records, but also realistic and viable

business and deployment plans.

This paper first examines the current state of

broadband access and the importance of havingthis access. Then, a quick overview of the electric

power grid and how it can be altered to allow

BPL sets the stage for a review of the current BPL

players, field trials, commercial deployments,

and standards bodies. This is followed by a brief

examination of the potential benefits of BPL to

the electric utility companies, service providers,

and end-users and a look at the main

challenges for BPL, namely harsh power line

channel characteristics and performance issues,

interference concerns, and the regulatory

activities surrounding BPL. The paper continues

with a review of the BPL business models and

economic issues before presenting conclusions

and closing remarks.

BROADBAND ACCESS

Current State of Access

Despite the widespread and spectacular growth

of broadband technologies in the last few years,

significant regions of the world, including rural

and low income areas in the US, still do not have

access to broadband services. In fact, out of the6.7 billion people who currently inhabit our

planet, roughly 3.7 billion (60 percent) have

access to electrical power services, whereas only

about 2 billion (30 percent) have access to some

type of telephony services (wireline and/or

wireless), and only roughly 250 million

(3.7 percent) have access to broadband

services [2, 3]. In the US, out of a population of

300 millionand using a relaxed definition

of broadband as only 200 kbps in at least one

direction (Internet to user [receiving or downlink]

or user to Internet [transmitting or uplink])only

roughly 50 million people currently have accessto broadband services.

A major hurdle to deploying broadband services

is the high cost of deploying the so-called last-mile

access. The last mile (also sometimes referred

to as the first mile, local loop, or access network)

is defined as the part of the network that

links users with broadband services. From a

communications perspective, power lines, due to

their omnipresence and the fact that they have

already reached electrical power users in homes

and offices, would seem to solve this access issue.

In this sense, they may be considered as a

possible third set of broadband wires reaching

homes or businesses (the other two being

DSL and cable modem). Of course, last-mile

broadband access could also be provided

wirelessly via fixed wireless, cellular, or

satellite systems.The wiring inside a home or office can also be

used to provide a local area network (LAN)

connecting computers, printers, and smart

appliances and basically turning every outlet into

an Internet connection. This is sometimes referred

to as last-inch access or connectivity.

It is worth noting that while industrialized

countries typically have severalalbeit

sometimes prohibitively priceytelephony and

broadband options, less developed countries may

have access only to power line services and

frequently lack well-established conventionaltelecommunications infrastructure. It is here that

power line communications can be particularly

useful and effective. Households connected to

power lines may be quickly provided with

telephony via voice over Internet Protocol (VoIP)

and broadband Internet services, with minimal

need for a new major infrastructure and its

associated huge financial investment. For many

of those underserved communities, this would be

their first access to telephony, Internet, and

related services.

Importance of Access

Numerous studies have shown a direct

relationship between the availability and

penetration rate of broadband and an

improvement in productivity, quality of

education, quality of health care, generation of

new high-paying jobs, and facilitation of new

channels for commerce. These, in turn, can all

lead directly to national economic growth (with a

direct impact on gross domestic product [GDP])

and even enhanced national security. According

to Thomas L. Friedman, the frequently quoted

op-ed commentator on globalization:Jobs, knowledge use and economic growthwill gravitate to those societies that are themost connected, with the most networks andthe broadest amount of bandwidthbecausethese countries find it easiest to amass,deploy and share knowledge in order todesign, invent, manufacture, sell, provideservices, communicate, educate and enter-tain. Connectivity is now productivity. [4]

January 2007 Volume 5, Number 1 3

Considering that

broadband

penetration is

currently less than

4 percent globally,

the huge growth

potential for the

broadband market

is obvious.

BPL could provide

a quick and

attractive solution.


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Unfortunately, both nationally and globally, a

large digital divide, or gap, separates those

with regular and effective access to digital

technologies and those without. More

specifically, a gap exists between people who

have effective high-speed Internet access (the

information haves) and those who do not (the

information have-nots). Realizing the importance

of broadband, US President George W. Bush, on

April 26, 2004, called for providing universal andaffordable broadband access in every part of

America by 2007 as part of his initiative to create

A New Generation of American Innovation [5].

With respect to the presidents broadband

initiative, BPL could play an important role

by offering:

Affordability: With no need for new wiring

or major infrastructure deployment, BPL

creates an alternative broadband solution

that could lead to lower prices for broadband

consumers.

Universality: BPL could facilitate and speed

up connecting the rural and low income

parts of America to broadband services,

thereby helping to bridge the digital divide.

Thus, power lines could perform double duty by

delivering electrical power services and

providing broadband information services. BPL

deployment, in turn, holds the promise of

providing both telephony (via VoIP) and

broadband services to all 3.7 billion people on

our planet who have access to power lines!

It is also worth mentioning that power line

communications (PLC) is not a new subject, but

one that has been around for decades. Several

power companies around the globe have been

using power lines for low-speed applications

(a few kbps in the low frequency [LF] portion of

the spectrum), such as power line meteringand control. The recent renewed interest in

using power lines for communications revolves

specifically around providing BPL applications.

The main idea is to use specialized equipment

to slightly modify the existing power grid to

allow it to also carry high speed data over a

broad spectrum range (high frequency [HF], the

lower portion of very high frequency [VHF],

and potentially beyond) without causing

unreasonable interference to the rightful

incumbent users of those RF bands. Furthermore,

this has to be done in an economically and

financially viable manner.

ELECTRIC POWER GRID

Overview of Grid Structure and Topology

While the details of electric power grid structures

and topologies differ from country to country,

High VoltageTransmission Lines

Medium VoltageTransmission Lines

PowerSubstation

Power Plant

PowerSubstation

Low VoltageTransmission Lines

Low VoltageTransmission Lines

Medium VoltageTransmission Lines

High Voltage Transmission(69 kV and Above)

Primary Distribution Medium Voltage(2.4 to 35 kV)

Secondary Distribution Low Voltage(Up to 600 V)

Figure 1. Typical Electric Power Grid

US President

George W. Bush,

in April 2004,

called for providing

universal and

affordable

broadband access

in every part of

America by 2007

as part of his

initiative to create

A New Generation

of American

Innovation.


5/20


a power grid basically consists of power

plants or generators, transmission substations,

transmission lines, power substations with

transformers to change voltage levels, and

distribution lines that collectively generate

and carry the electricity from power plants all

the way to wall plugs. See Figure 1.

Power plants are basically spinning electricity

generators. Spinning can be performed by a

steam turbine, and steam can be created by

burning fossil fuel or from a nuclear reactor.

A generators output is three-phase alternating

current (AC) power at voltage levels in the

thousands. The three single phases are

synchronized and offset by 120 degrees.

Three-phase current is chosen because single-

phase AC goes through a full cycle (from zero

to peak to zero to other peak and back to

zero) at the line rate, which is 60 timesper second in the US and 50 in the other parts

of the world. With three synchronized phases, on

the other hand, one of the three phases is nearing

a peak at any given instant. More phases could be

used, but this implies more wires and higher cost;

three seems to be a good compromise between

cost and performance.

Power P, transferred over lines and delivered to

customers, is equal to the product of voltage V

and current I (P = IV). Power loss in the line

grows with the square of the current, that is,

Ploss = Rline I2, where Rline is the line resistance

and depends on the line material and increases

with the length of the line. For a given generated

P and a given Rline , to reduce Ploss , current Imust

be made as small as possible. This means that

the line voltage must be made as large as possible,

especially for long-distance transmissions.

Transmission substations located next to power

plants use large transformers to step up generator

output from thousands of volts to hundreds of

thousands of volts (typically between 155,000 and

765,000 volts), thus allowing megawatts of power

transmission over distances of 300 miles or more.

At power substations, voltages are stepped down

and lines are branched out to cover larger areas.

This is performed successively, transforming and

branching out from extremely high voltage (EHV,

typically 155 to 765 kV) to high voltage (HV,

typically 45 to 155 kV), and then from HV to

medium voltage (MV, typically 2 to 45 kV), and

finally from MV to low voltage (LV, typically

100 to 600 V) for delivery to homes or businesses.

The result is a tree-structured power distribution

hierarchy. Basically, EHV and HV are used to

transmit AC electric power, and MV and LV are

used to distribute it. See Figure 2.

The structures needed to support EHV and HV

lines are typically tall, massive towers. MV and

LV lines, on the other hand, are typicallymounted on street poles. In the US, street poles

are typically 10 meters high, located 50 meters

apart, and support three wires that carry the

three separate phases, plus a neutral (possibly

grounded) wire. A network of MV lines is usually

referred to as the primary distribution; a network

of LV lines is the secondary distribution.

In the US, at the primary distribution level, most

power lines are aerial or overhead. At the

secondary distribution level, particularly in

newer urban areas, most lines run underground.

Overhead lines are more susceptible thanunderground lines to producing radiation

interference and to picking up interference. But

underground lines are used less due to the

prohibitive cost of burying cables. In the US,

MV lines typically run between 15 and 50 km.

As mentioned, levels and structures of branching,

network architectures, and voltage levels vary

from country to country. For instance, in the US,

TransformerGeneration

MV

EHV HV MV

MV

MV

MVHV

HV

Transformer

Transmission Distribution

LV

LV LV

LV

LV

LVLV

LV

LV

Consumption

Figure 2. From Generation to Consumption: Power Grid Hierarchies

A power grid

basically consists

of power plants

or generators,

transmission

substations,

transmission lines,

power substations

with transformers

to change

voltage levels, and

distribution lines

that collectively

generate and

carry the electricity

from power plants

all the way

to wall plugs.


6/20


typically fewer than a dozen homes are served

by a single MV/LV transformer, whereas in

Japan this number is about 30 and in Europe it

is several hundred. This affects not only the

communications characteristics, but also the

economic viability of a BPL system. (BPL business

models are examined later in this paper.)

Altering the Power Grid To Allow BPL

EHV and HV lines are usually too noisy totransmit broadband communications signals;

only MV and LV lines are used for BPL. MV

lines are usually less branched than LV lines,

making point-to-point connections possible.

MV networks allow communication over

longer distances because of their weaker signal

attenuation and lower noise level.

To use power lines for broadband communi-

cations, the broadband signal must be injected

into and extracted from the lines through

couplers. LV couplers may be capacitive or

inductive, depending on distribution systemtopology, performance requirements, and cost. In

capacitive coupling, a capacitor is responsible for

the actual coupling, and the signal is modulated

onto the networks voltage waveform. In

inductive coupling, an inductor is used to couple

the signal onto the networks current waveform.

Inductive couplers are known to be rather lossy,

but since they require no physical connection to

the network, they are safer to install on energized

lines than capacitive couplers. MV couplers are

typically inductive. It is important that couplers

be easy-to-install passive devices with low failurerates that can be used outdoors and installed on

energized lines.

Line noise, limitations on the amount of signal

power that can be injected into power lines

without causing unacceptable interference for

other spectrum users, and signal attenuation as

the signal traverses the line make it necessary to

regenerate or repeat the signal periodically. This

can be done by using MV couplers to couple the

broadband signal off of the MV line so that it can

be regenerated if necessary and amplified before

being fed back onto the MV line through another

coupler. Repeaters, on the other hand, could add

latency (especially if the signal is regenerated)

MobileNetwork

PSTN

BackhaulBox

Power Substation

Backhaul Network

Internet

Access BPL In-House BPL

Power Generator

MVLines

MV Coupler

MVLines

HVTransmission Lines

RepeaterBox

TransferBypass

Box

MVCoupler

LV CouplerMV

Coupler

LV Lines

PC

VoIPPhone

MVLines

LV Lines toHomes/Businesses

MVLine

MVCoupler

LVCoupler

LV Line toHome/Business

TransferBypass

Box

Transformer

LVLine

Coax

Figure 3. Typical BPL Architecture

Couplers should be

easy-to-install

passive devices

with low failure

rates that

can be used

outdoors and

installed on

energized lines.


7/20


and could also create single points of failure,

because a single bad repeater can bring down an

entire communications line.

The distribution transformers that changevoltage levels between MV and LV lines are

particularly harsh on the weak broadband signal.

Transformers, which are intended to pass low

frequencies near 50 or 60 Hz, appear as open

circuits for the passage of higher frequency

signals and typically attenuate and distort the

weak broadband signal beyond reconstruction

and usability. This implies that BPL signals

going between MV and LV lines need to bypass

the transformers. Typically, the bypass box can

also have built-in repeating functionality at a

small incremental cost. The recent capability to

effectively and safely bypass transformers hasbeen instrumental to the success and deployment

of BPL.

A point-of-presence (POP) is needed to connect

the BPL network to a backhaul network such

as the Internet, a public switched telephone

network (PSTN), or a mobile network. The

connection is made through a backhaul network

box coupled to an MV distribution line, typically

next to a power substation where multiple

MV lines are connected. The backhaul network

box is typically a bidirectional device that

converts data formats, aggregates andconcentrates uplink data streams, provides

routing functionality, helps allocate bandwidth

and resources, generates billing and charging

data, and provides various backhaul Ethernet

interfaces to fiber optic or wireless connections.

Figure 3 illustrates a typical BPL architecture.

A BPL network, like any other communications

network, also requires a network management

system (NMS) or operations support system

(OSS) to observe and manage network resources

and perform billing and other back-end tasks.

BPL Deployment Options

The MV and LV line portions of the BPL are

usually referred to as the access BPL, while the

portion inside a home or office using the inside

wiring is called the in-house BPL. BPL can be

deployed either as end-to-end BPL or as hybrid

BPL, using one of the three options illustrated

in Figure 4.

An end-to-end BPL system uses both access

BPL and in-house BPL, i.e., power lines are used

all the way from the power substation to

the end user. Two of the three BPL deployment

options involve the access BPL portion of an

end-to-end system: the BPL signal can either

(1) bypass the MV/LV transformer (as does

CURRENT Technologies equipment) or (2) go

through the transformer (as does MainNet

Communications equipment).

The third BPL deployment option is hybrid BPL.

In this option, typically only the MV lines are

used, and a fixed wireless network replaces the

LV lines and in-house BPL (Amperion takes

this approach). In hybrid BPL, the bypass box

does not couple the broadband signal to/from

the LV line but converts it to/from a wirelessformat and delivers it to the wireless access point

(AP) also located on the pole.

These different deployment options have their

associated performance and cost tradeoffs. For

end-to-end BPL, bypass boxes and LV couplers

must be installed on all LV lines, and in-house

BPL modems are required. For hybrid BPL,

bypass boxes with wireless conversion boards,

The MV and LV line

portions of the BPL

are usually

referred to as

theaccessBPL,

while the portion

inside a home or

office using the

inside wiringis called the

in-houseBPL.

BPL can be

deployed either

as end-to-end BPL

or as hybrid BPL .

Substationwith Modem

Injector

Option 1Transformer

Bypass System

Option 3Wireless Connection

Option 2

ThroughTransformer

Repeater

Extractor

Coupler

Coupler

Router

WirelessTransmitter

with AntennaWireless Receiver

with Antenna

Figure 4. BPL Deployment Options


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wireless APs, and existing standard wireless

user modems are required, but LV transformer

bypasses and LV couplers are not. Also

associated with hybrid BPL are the usual

existing issues regarding wireless performance

in unlicensed spectrum and the current state

of wireless quality of service (QoS), security,

and so forth.

INDUSTRY PLAYERS, FIELD TRIALS,

COMMERCIAL DEPLOYMENTS, AND

STANDARDS BODIES

Industry Players, Field Trials, and

Commercial Deployments

Globally, the number of BPL players (electric

utility companies, equipment manufacturers,

investors, etc.), field trials, and commercial

deployments has been growing steadily in the

last few years. In the US alone, there have been

more than 39 trial deployments [6]. CURRENT

Technologies is currently offering commercialBPL services with Duke Energy in Cincinnati,

Ohio, with plans to expand elsewhere within

Dukes 1.5-million-customer service territory in

Ohio, Indiana, and Kentucky. CURRENT

Technologies is also planning to deploy BPL

services to potentially 2 million residents of

Dallas, Texas, using TXU Electric delivery. The

City of Manassas, Virginia, has been offering

citywide BPL services using MainNet equipment

since 2005. Progress Energy and EarthLink plan

to provide BPL services in North Carolina using

Amperion equipment.

There are also commercial deployments in Spain,

Germany, Korea, Chile, Brazil, and the UK.

In Spain, Endesa began service in 2003

in Saragossa and Barcelona; Iberdrola initiated

service in Madrid and Valencia in the same year.

Power Plus Communications has started offering

services in Germany, as has Scottish Southern

Electric in the UK.

Standards Bodies

Standardization is of paramount importance

to the success of any new technology

such as BPL. To this end, the Open PLCEuropean Research Alliance (OPERA), European

Telecommunications Standards Institute (ETSI),

Institute of Electrical and Electronics Engineers

(IEEE), Universal Powerline Association (UPA),

European Committee for Electrotechnical

Standardization (CENELEC), and HomePlug

Powerline Alliance have been leading the

activities and creating their own standards.

OPERAa consortium of currently 37

organizations, including electric utility

companies, PLC equipment manufacturers, and

universitiesis a research and development

(R&D) project with funding from the European

Commission to create and promote open global

specifications for low-cost, high-performance,

high-speed power line communications. Its

first specification documents were released on

February 21, 2006. These specifications will bepromoted through international standardization

organizations, including IEEE and ETSI [7].

The IEEE BPL study group drove the creation

of the BPL-related Pxxxx working groups.

The IEEE P1675 Standard for Broadband

over Power Line Hardware Working Group

is chartered to develop standards for

power line hardware installation and safety.

The IEEE P1775 Powerline Communication

Equipment Electromagnetic Compatibility

(EMC) Requirements Testing and Measurement

Methods Working Group is focused on

PLC equipment, electromagnetic compatibility

requirements, and testing and measurement

methods. The IEEE P1901 Draft Standard

for Broadband over Power Line Networks:

Medium Access Control and Physical Layer

Specifications Working Group is responsible for

defining the medium access control (MAC) and

physical layers for high speed (greater than

100 Mbps at the physical layer) for both

in-house and access BPL. The standard will focus

on transmission frequencies below 100 MHz.

The specifications of these working groups are

scheduled for release in 2007 [8].The UPA has also released a number of

specifications related to different aspects of

power line technology. Three main specifications

are the UPA coexistence specification, released in

June 2005; the UPA access BPL specification,

endorsed by OPERA and released in

February 2006; and the UPA in-house BPL

specification, called Digital Home Standard v1.0

and also released in February 2006. The UPA

also works with and through international

standardization bodies such as IEEE and ETSI to

promote its standards [9].

The HomePlug Powerline Alliance was founded

in 2000 and currently has over 65 member

companies. The alliances standards (HomePlug

1.0 and AV) are for home networking over

power lines (in-house BPL). The HomePlug 1.0

specification allows for speeds up to 14 Mbps.

The current HomePlug AV specification allows

for speeds greater than 100 Mbps (suitable for

Globally,

the number of

BPL players (electric

utility companies,

equipment

manufacturers,

investors, etc.),

field trials, and

commercialdeployments

has been growing

steadily in

the last few years.


9/20


high definition television [HDTV] and VoIP) and

is compatible with HomePlug 1.0. In 2004, to

provide a harmonized end-to-end BPL standard,

the HomePlug Powerline Alliance started looking

into creating an access BPL standard planned for

completion by early 2007 [10].

POTENTIAL BENEFITS

Benefits to Service Providers

From a service providers point of view, BPL

could provide large cost savings. The first, and by

far the most important, factor is that the

transmission medium, i.e., the power lines, is

already in place. There is no need to purchase

spectrum or to hang, dig, or lay new wires,

because most of the required infrastructure

already exists. There is also no need for the

difficult, expensive, and time-consuming site

acquisition, permitting, and licensing tasks

needed for a typical deployment. Given the

omnipresence of power lines, BPL also holds thepromise of being able to provide genuinely

ubiquitous coverage. These factors imply

potential cost and time savings that could level

the BPL deployment playing field a bit more

compared with DSL and cable, both of which

have significant deployment head starts.

Benefits to Electric Utilities

For the electric utility companies, BPLs benefits

are twofold: (1) It can create new sources of

revenue from an existing investment, and

(2) it can help create a smart grid for the utilitycompanies that would enable enhanced utility

applications [11, 12] such as:

System monitoring from any point on the

electric grid

Load shifting and balancing

Optimized asset utilization and management

Performance of preventive maintenance and

improvement of service reliability and

customer satisfaction by avoiding power

outages and emergencies

Advanced supervisory control and data

acquisition (SCADA)

Fault detection, fault analysis, and adaptive

self-healing

Automatic outage detection, restoration

detection, and verification

BPL-enabled electricity meters that enable

time-of-day and real-time pricing through

automated meter reading (AMR) with

remote disconnect (and reconnect) and

theft detection

Real-time video surveillance of the sensitive

national power infrastructure (e.g., grid

and substations)

Benefits to End Users

End users can benefit from BPL deployment

because:

BPL could create competition and thus help

reduce end-user service prices.

BPL could provide high user throughputs,

as discussed later in this paper.

In some places, BPL may be the only viable

choice (e.g., in rural areas), although satellite-

based service may also be of interest in

these areas.

BPL could be used for smart appliances,

connected and controlled through a PC andremotely. While these devices could possibly

be controlled through a DSL or a cable

modem connection, BPL may provide a more

integrated (neater) solution.

BPL may provide a more ubiquitous and

reliable service coverage area.

The explosive growth of the Internet and the

recent deregulation of telecommunications in the

US and Europe have led to the renewed interest

in BPL. Extensive research on BPL channel

modeling [1320] and a considerable amount of

interference analysis [2125] have taken place.Concurrently, there have been a large number

of field trials and measurements to validate

various models [2131], along with advances in

signal processing such as the newer adaptive

modulation and coding techniques [28] and

faster, cheaper processors and electronics.

Nonetheless, despite its renewed attractiveness,

BPL must overcome implementation challenges

as well as regulatory concerns before it can

become a viable avenue of broadband access. The

next sections of this paper examine in more

detail the key implementation challenges and

regulatory concerns facing BPL.

IMPLEMENTATION CHALLENGES

The Nature of the Power Grid

The most obvious challenges to implementing

BPL arise from the fact that power line grids were

originally developed to transmit electrical power

The explosive

growth of the

Internet and

the recent

deregulation of

telecommunications

in the US and

Europe have led to

the renewedinterest in BPL .


10/20


(high voltage AC at low frequencies of 50 or 60 Hz)

from a small number of sources (the generators)

to a large number of sinks (the end customers).

Power grids were neither designed nor devised

for communications purposes. Even though the

interest in using power lines for communications

is not new, their early use for data transmission

was mainly for simple, low-data-rate (a few

kilobits per second) remote monitoring and meter

reading applications at a low frequency (typicallyonly up to a few hundred kilohertz).

The main challenges to BPL arising from the

nature of the power grid have been the extremely

harsh, unpredictable, time-and-location-variable

characteristics of the power line channel,

and potential interference concerns (in both

directions) [1325]. Because power lines are not

twisted and have no shielding, they can produce

electromagnetic radiation that is easily detected

by radio receivers. For the same reasons, power

lines can also easily pick up nearby radio

frequency signals. Thus, addressing mutual

interference is not only a challenge, but becomes

a valid regulatory concern.

A related challenge facing BPL centers around

data sensitivity. To prevent interception of

sensitive data by unintended and unauthorized

receivers, data encryption is a must.

The fact that the power line grid is a shared

medium and BPL is a contention-based system

creates additional challenges. Because all users

share the available channel capacity or

bandwidth, as the number of users goes up,

per-user throughput goes down. In the US, thereare typically 50 homes per substation. An average

available throughput of 50 Mbps implies roughly

an average of 1 Mbps per user, a speed on par

with the current average speeds delivered by DSL

or cable modem. However, BPL is thought to be

distance limited, similar to DSL. Thus, the

distance between the customers home and the

supplying substation is a factor in the

bit rate available to the user.

Channel Characteristics and Capacity

Power Line NoiseIn general, a power line channel is a very

harsh and noisy transmission medium. The noise

on the line is typically time, location, and

frequency dependent.

Time-variable behavior is due mainly to the

dynamically changing nature of the load

connected to the power lines. Line branching, the

number and types of branches, the lengths of line

segments, the types of power line equipment

connected (such as capacitor banks and

transformers), and the kinds of loads connected

all affect channel characteristics. Furthermore,

impedance mismatches caused by unterminated

stubs and line branches cause signal reflections

and create a frequency-dependent fading

channel, much like the multipaths typically seen

in mobile wireless communication channels.

MV and LV lines have very different noisecharacteristics. The MV grid is usually less

branched than the LV grid, and LV lines are

typically terminated at time-varying consumer

electrical appliances. Noise on the LV grid is

typically the sum of background noise, impulsive

noise, and synchronous/nonsynchronous (with

the power line frequency) colored noise,

generated primarily by electrical appliances; this

noise is certainly not an additive white gaussian

noise (AWGN). On the MV grid, the on/off

switching of the capacitor banks used to correct

the power factor typically causes high noise

peaks [14]. At the same time, background noise

and narrow-band noise are dominant on MV

lines. The background noise is environmental

noise that is highly dependent on weather,

location, and elevation. The narrow-band noise

is caused by RF interferers such as amateur or

shortwave (SW) radios and varies randomly

across location and time. Noise levels on

MV lines are typically as much as 20 to 30 dB

higher than on LV lines in the frequency range

of 1 to 20 MHz [21].

Channel Attenuation

Power lines have been modeled in the literatureby using either statistical approaches based

on extensive measurements or deterministic

approaches based on multiconductor trans-

mission line (MTL) theory and numerical

analysis. Carsons earlier MTL model [17]

allowed for ground impedance but did not

include ground admittance, which cannot be

ignored in higher frequencies and/or under

poor conductive ground plane conditions.

The subsequent MTL models in [18, 19] include

ground admittance.

A simple matched uniform MV line segment withno connected device or junctions could have as

little as 1 dB/km ohmic absorption or attenuation

loss. For a complex overhead MV network, on the

other hand, the amplitude of the channel

frequency response (or, equivalently, the channel

attenuation) in the frequency range of 10 kHz to

100 MHz shows highly frequency-dependent

attenuations of as high as 40 dB/km caused by

reflections from abrupt discontinuities and

The main challenges

to BPL arising from

the nature of

the power grid

have been

the extremely harsh,

unpredictable,

time-and-

location-variablecharacteristics of

the power line

channel,

and potential

interference

concerns (in both

directions).


11/20


mismatched impedances [23]. LV network losses

are typically higher than MV network losses and

could be as high as 100 dB/km [14].

Performance Improvements

Conditioning the grid can improve power

line performance by minimizing impedance

mismatches, terminating stubs, filtering noise,

etc. These options, however, may deteriorate or

diminish the advantages of power line grids. A

better approach is to use modulation and codingschemes robust enough to work in the hostile

power line channel environment. Currently, most

BPL products use orthogonal frequency division

multiplexing (OFDM), well known for its

excellent robustness against channel distortions

such as multipath and impulsive noise and for its

good spectral efficiency, reasonable cost, and

ability to avoid certain bands.

In BPL systems, multiple user modems are

connected in a bus or star topology. Some type

of MAC must be implemented to provide

communications through shared bandwidth onpower lines. To provide the necessary QoS

for applications that require bandwidth

and performance guarantees, such as video

streaming, the carrier sensing multiple

access/collision avoidance (CSMA/CA) protocol

may be used. This widely used scalable

protocol, also used in the wireless fidelity

(IEEE 802.11) MAC layer, is suitable for power

line channel characteristics.

Capacity and Spectral Efficiency

Depending on the bandwidth used on the powerlines (typically a frequency range between 2 and

100 MHz), on the BPL injection power level

(typically 1 to 30 dBm), and on load and channel

conditions, throughputs in the range of tens, or

even hundreds, of megabits per second and

spectral efficiencies in the range of 1 to 20 bps/Hz

can be achieved [20]. Theoretical and field trials

have also claimed throughputs of the same order

of magnitude, and even in the gigabit-per-second

range if larger frequency bandwidths in

the upper VHF/ultra high frequency (UHF)

spectrum and higher input signal powers are

used. In the US, however, this may not be a viableoption, considering that licensed spectrum in the

VHF and UHF bands is heavily occupied.

A system developed by Corridor Systems, Inc., in

the US uses MV power lines in frequency ranges

from VHF through microwave as distributed

antenna systems (DASs) to extend existing

cellular network coverage [29]. The cellular

network RF signal is picked up by the Corridor

equipment, converted into a proprietary BPL

format, and injected into and transported down

the MV lines. At cellular dead zones, the Corridor

equipment converts the signal back to its original

format for re-radiation by local antennas. Thus,

MV lines are used to carry cellular signals to areas

too difficult or expensive to reach by cellular

networks, conventional repeaters, or DASs.

Interference Concerns and Regulatory IssuesUnlike the twisted wires of telephone companies

and the shielded cables of cable companies, long

unshielded, untwisted, overhead power lines can

act as large antennas and be natural sources and

targets of electromagnetic interference (EMI). In

addition, BPL signals tend to radiate from the

injectors and repeaters spaced along the power

lines. This raises concerns about interfering

with the rightful owners of the radio spectrum in

the BPL range of operation [30]. The most

concerned and vocal opponents of BPL in the

US are amateur radio operators, through the

American Radio Relay League (ARRL), andgovernment agencies.

The US FCC started examining the use of power

lines for broadband communications services by

issuing a Notice of Inquiry (NOI) on April 23,

2003. The NOI sought information on potential

interference from BPL systems and associated

changes that may be needed to accommodate BPL

systems in Part 15 of the FCCs rules published

in the Telecommunications Code of Federal

Regulations (47 CFR).

Part 15 addresses RF devices. Part 15, Subpart A,addresses general issues. Section 15.3 defines

terms used in the FCCs rules. Subpart B

addresses unintentional radiators, with Section

15.109 defining the radiated emission limits.

Subpart C deals with intentional radiators, with

Section 15.209 defining the corresponding general

requirements and radiated emission limits.

Section 15.3 (f) defines a carrier current system as

a system, or part of a system, that transmits RF

energy by conduction over electric power lines.

A carrier current system can be designed so that

the RF signals are received by conduction directly

from the connection to the electric power lines

(unintentional radiator) or so that the signals are

received as over-the-air radiation from the

electric power lines (intentional radiator). Carrier

current systems operate on an unlicensed basis

under Part 15. As a general condition of

operation, Part 15 devices may not cause harmful

interference to authorized radio services and

must accept any interference they receive.

Unlike the

twisted wires of

telephone

companies and

the shielded cables

of cable companies,

long unshielded,

untwisted, overhead

power lines can actas large antennas

and be

natural sources

and targets of EMI.


12/20


The FCC amended the existing Section 15.3 to

include Sections 15.3 (ff) for access BPL and

15.3 (gg) for in-house BPL, as follows:

Section 15.3 (ff) Access BPL: A carriercurrent system installed and operated on anelectric utility service as an unintentionalradiator that sends radio frequency energyon frequencies between 1.705 MHz and80 MHz over medium voltage lines or overlow voltage lines to provide broadband

communications and is located on thesupply side of the utility services points ofinterconnection with customer premises.

Section 15.3 (gg) In-House BPL: A carriercurrent system, operating as an unintentionalradiator, that sends radio frequency energyby conduction over electric power lines thatare not owned, operated or controlled by anelectric service provider. The electric powerlines may be aerial (overhead), underground,or inside the walls, floors or ceilings ofuser premises. In-House BPL devices mayestablish closed networks within a userspremises or provide connections to AccessBPL networks, or both.

In its response to the FCCs NOI, the

National Telecommunications and Information

Administration (NTIA) of the US Department

of Commerce described the federal governments

usage of the 1.7 to 80 MHz spectrum, identified

associated interference concerns, and outlined the

studies it planned to conduct to address those

concerns. In April 2004, the NTIA published

its Phase 1 Study technical report, NTIA

Report 04-413, Potential Interference from

Broadband over Power Line (BPL) Systems to

Federal Government Radiocommunications at1.7 80 MHz [31]. In this report, the NTIA

defined interference risks to radio reception in the

immediate vicinity of overhead power lines

used by an access BPL system. The radio systems

to be considered in interference analyses included

a land vehicular receiver, a ship-borne receiver,

a receiver using a rooftop antenna (e.g., a base

or fixed-service station), and an aircraft receiver

in flight. The study included various

measurement campaigns and the use of

numerical electromagnetic code (NEC) software

to characterize BPL signal radiation and

propagation and to evaluate interference risks.

The report also suggested means for reducing

interference risks and identified techniques for

mitigating local interference should it occur.

The Phase 1 Study focused on simple BPL

deployment models. The Phase 2 Study is

focusing on evaluating the effectiveness of the

NTIAs Phase 1 recommendations and on the

results of a study of potential interference via

ionospheric propagation of BPL emissions

resulting from the mature large-scale deployment

of BPL networks. As of the date of this paper, the

Phase 2 Study report had not yet been released.

Some of the NTIAs Phase 1 Study highlights

include:

In the 1.7 to 80 MHz spectrum, the dominant

propagation modes are ground waves, space

waves, and sky waves. Ground waves consistof direct waves, ground-reflected waves, and

surface waves. Direct waves decay at a rate

proportional to the square of their distance

from their source. Ground-reflected waves

(along with direct waves) decay at the rate of

distance raised to the power of four. Ground-

reflected waves may be of no major concern if

the radiator is relatively far from ground.

Surface waves propagate close to the ground

and have a substantially higher rate of

attenuation than direct waves. Ground wave

propagation is pertinent on BPL signal paths

below the power line horizon. Space wavesinvolve only direct waves and occur over

elevated signal paths, e.g., signal paths above

the power line horizon. Sky waves are

particularly important in the HF band (for

BPL, 1.7 to 30 MHz) and have temporal and

spatial variability. Here, signal paths are

represented as rays reflected and refracted by

the ionosphere. Sky waves can extend the

signals reach to several kilometers.

The space around a radiator is typically

divided into three regions: reactive near-

field, radiating near-field, and far-field.These regions are typically defined as:

where ris the distance from the radiator, D is

the largest linear dimension of the radiator,

and is wavelength. For BPL systems, the

victim receiver is typically in the radiating

near-fields, although far-fields are important

because of sky waves and at distances seen

by aircraft receivers.

D3

r< 0.62

D3

0.62 < r< 2

D2

r> 2

D2

Reactive Near-Field

Radiating Near-Field

Far-Field

The FCC amended

the existing

Section 15.3

to include

Sections 15.3 (ff)

for access BPL

and 15.3 (gg)

for in-house BPL .


13/20


The NTIA also provided some recommendations

and suggested some interference mitigation

techniques; these include:

Mandatory registration of certain parameters

of planned and deployed BPL systems

A requirement for BPL devices to be

frequency agile (i.e., to have notching and

retuning capabilities) and to have remote

power reduction and shutdown capabilitiesto eliminate interference if any is reported

Use of minimal required power

Avoidance of locally used radio frequencies

Use of symmetry and differential mode

signal injection to minimize radiation [31, 23].

Symmetry is defined in terms of impedance

between conductors and ground. If, for a

two-wire line, the impedance between each

conductor and ground is equal, the line is

symmetrical or balanced. Balanced lines are

necessary for differential mode transmission,in which the currents are equal in magnitude

and flow in opposite directions on the

conductors. The fields radiating from these

conductors tend to cancel each other.

Subsequent to the above activities, the FCC

released its Notice of Public Rule Making

(NPRM) in February 2004, and received more

than a thousand comments and replies from

many concerned parties [32]. The FCC eventually

finalized its decision by adopting its Report &

Order (R&O) FCC 04-245 on October 14, 2004

(published in the Federal Register on January 7,

2005) [33]. The FCC considered various petitions

to reconsider the R&O and subsequently

amended the Part 15 rules to modify some of the

previous specified exclusion zones and add a few

new exclusion zones. However, the FCC denied

other petitions to reconsider other aspects and

published the final Memorandum Opinion &

Order (MO&O) on August 7, 2006, and the new

amended rules in 47 CFR.

The FCC basically decided to keep BPL under

existing Part 15 unlicensed device rules and

added Subpart G for access BPL. More

specifically, Sections 15.601, 15.607, 15.611, and15.613 of this new Subpart include the following

new rules:

Exclusion Bands: These are certain bands

of frequencies within which access BPL

operations are not permitted.

Exclusion Zones: These are certain

geographic areas within which access

BPL operations are not allowed.

Consultation: A consultation is to be held

between an entity operating access BPL and a

licensed public safety or other designated

point of contact, for the purpose of avoiding

potential harmful interference.

Equipment Authorization: Because BPL is a

new technology, the FCC has required that

all BPL-related equipment be certified.

Certification is an equipment authorization by

the FCC or its designated entities, as opposedto verification, which is a manufacturers self-

approval procedure. The rules adopted in the

R&O require that all access BPL devices

manufactured, imported, marketed, or

installed 18 months or later after the Federal

Register publication of the R&O (i.e., after

July 7, 2006) must comply with the

newly adopted requirements of Subpart G

of Part 15 for BPL devices, including

certification of the equipment.

Databases: Publicly available databases are

to be created and maintained by an industry-sponsored entity recognized by the FCC and

the NTIA. They are to contain information

regarding existing and planned access BPL

systems. Each database should be available

within 30 days before initiation of the specific

systems service and should include the

following information:

The name of the access BPL provider

The frequency of the access BPL

operation

The postal ZIP codes served by the

specific access BPL operation

The manufacturer and type of access

BPL equipment and its associated

FCC identification, etc.

Complete contact information for a

person at the BPL operators company

in charge of resolving any interference

complaints

The proposed or actual date of access

BPL operation

Interference Mitigation and Avoidance:

Access BPL systems are basically required toadhere to the NTIA recommendations for

interference mitigation and avoidance

mentioned above.

Field Limits: Access BPL systems that

operate in the 1.705-to-30-MHz band over

MV lines must comply with the radiation

limits for intentional radiators provided in

Section 15.209. Systems operating in the

Because BPL is

a new technology,

the FCC has

required that

all BPL-related

equipment

be certified.

Certificationis

an equipmentauthorization

by the FCC or its

designated entities,

as opposed to

verification, which is

a manufacturers

self-approval

procedure.


14/20


30-to-80-MHz band over MV lines mustcomply with the radiation limits for

unintentional radiators provided in Section

15.109 (b). Systems operating over LV lines

must comply with the Section 15.109 (a) and

(e) limits. Radiation emission limits for access

BPL equipment are summarized in Table 1.

The FCC also decided to eliminate conducted

emission limits and testing for BPL systems

because of the danger and inconvenience

associated with measuring power line

conducted emissions.

Measurement Procedure and Guidelines:

The FCC requires that access BPL system

emissions be measured in situ to demonstrate

compliance with the new Part 15 rules.

Measurements are to be made at a minimum

of three overhead and three underground

representative points and according to the

measurement guidelines outlined in

Appendix C of the NPRM. For access BPL

systems installed on overhead power lines, to

take into account the effect of line length, the

received measurement antenna will be

moved down-line parallel to the power line,starting from the access BPL signal injection

equipment location, to find the maximum

emissions at each frequency within the

frequency range of the access BPL device.

The distance from the measurement antenna

to power line is the slant distance or range,

as shown in Figure 5.

Because the distances rspecified in the guidelines

may coincide with unsafe locations (e.g., the

middle of a highway), the guidelines also specify

how to extrapolate a distance correction factor

from measurements made at distances other thanas specified in the rules. For frequencies below

30 MHz, the measured values are reduced by

40 log(10) (30/r); for frequencies at or above

30 MHz, the measured value is increased by

20 log(10) (r/10). The guidelines also specify the

type of measurement antenna (loop or linear)

and the type of detector (peak, quasi-peak, or root

mean square [RMS]).

It is worth mentioning again that the FCC

recognized the interference potential of BPL

systems. That is why the FCC decided that, even

though access BPL systems remain under thenewly added Subpart G of Part 15 for unlicensed

device rules, their operations cannot cause

harmful interference and the systems must accept

any outside interference. Furthermore, any BPL

resultant interference must be corrected and

resolved by the BPL operator immediately,

without ceasing broadband service to the public.

On November 3, 2006, the FCC also decided to

classify BPL-enabled Internet access services as

information services. By virtue of being considered

information services, BPL services become free

from many, if not all, common carrier regulationsand associated fees and taxes. Specifically,

the FCCs Order finds that the transmission

The FCC recognized

the interference

potential of

BPL systems.

That is why the

FCC decided that,

even though access

BPL systems remain

under the newlyadded Subpart G

of Part 15

for unlicensed

device rules,

their operations

cannot cause

harmful interference

and the systems

must accept

any outsideinterference.

Power Line

Type

Frequency

(MHz)

Field Strength

Limits (V/m)Measurement

Distance (m)

LV or MV 1.70530 30 30

LV 3080 100 3

MV 3080 90 10

Table 1. Radiation Limits

RingAnten na

Antenn a Hei ght

Distance Specified in Rule (e.g., 30 m for


15/20


component underlying BPL-enabled access

services is telecommunications and that

providing this telecommunications transmission

component as part of a functionally integrated,

finished BPL-enabled Internet access service

offering is an information service. The FCCs

decision was based on its desire to regulate

similar services in a similar manner. The FCCs

Order places BPL-enabled Internet access services

on an equal regulatory footing with otherbroadband services such as DSL or cable modem

Internet access services [34].

The FCC may, however, still decide to require

BPL operators who provide VoIP services to

contribute to the Universal Service Fund (USF),

based on a percentage of their gross revenues.

The USF was created by the FCC in 1997,

following enactment of the Telecommunications

Act of 1996, primarily to ensure that rural

and low-income customers receive levels of

telecommunications service similar to those in

nonrural areas. All telecommunications carriers

that provide service internationally and

between states are required to contribute to the

USF. The Universal Service Administrative

Company (USAC) submits fund size and

administrative cost projections for each quarter

in accordance with FCC rules.

The FCC also released a new R&O in May 2006

regarding law enforcement and emergency

services [35]. More specifically, the FCC resolved

a second R&O in the Communications Assistance

for Law Enforcement Act (CALEA) and

Broadband Access Services proceedings. As a

result of this FCC Order, VoIP- and facilities-based broadband access providers, such as

BPL operators who provide VoIP services,

must bring their networks into compliance

with wiretap, surveillance, and other official

law enforcement and emergency services

requirements by May 14, 2007.

BUSINESS MODELS AND ECONOMIC ISSUES

Depending on their particular businessand financial objectives, electric utilitycompanies can choose one of three businessmodels with respect to their BPL deployment. As

presented below, each model has successively

more associated risks and rewards:

The Landlord or Retail Model: In this

model, the electric utility company leases

its facilities to another company (preferably

one with prior communications experience)

that builds and operates the BPL system.

End users interface only with this company

for all customer care, billing, and support.

The electric utility company only collects

leases on its facilities, and may also receive

smart-grid services from the same

BPL service builder/provider. This model

requires the lowest investment from the

electric company and provides it with a new

source of income along with its existing

investments. This is the lowest risk, if any,model for the electric company.

The Wholesale Model: In this model,

the electric company builds out the BPL

network and leases it to another company,

which wholesales the bandwidth to

communications service providers or

Internet service providers (ISPs) that operate

the network and interface with customers.

This is a medium risk option, and the BPL

network can be used to provide smart-grid

services for the electric company.

The Service Provider Model: This is themost aggressive model. The electric utility

company builds and operates the BPL

network and interfaces directly with the

customers. Here, the electric company needs

to acquire the communications expertise

required to build, operate, and maintain

the BPL network. Of course, the electric

company must also market the broadband

services. This model carries the most risk,

but offers the greatest potential return on

investment (ROI).

Currently, precise data regarding BPLdeployment costs is not publicly available.

Various estimates show that BPL costs per home

passed could range from $50 to $300, depending

on the electric grids architecture, the need for

repeaters, the number of homes connected to the

substation, and similar factors. This cost includes

not only the cost of equipment and installation,

but also the cost over time of maintenance,

equipment replacement, and upgrades.

Consumer premises equipment (CPE) costs

currently range from $50 to $200. Assuming a

conservative initial deployment with a subscriber

penetration rate of 10 percent (blended over rural,suburban, and urban areas), which is typical

of current initial deployment results, and a

$100-per-home-passed deployment cost and a

$100 CPE cost, the initial BPL deployment cost

becomes about $1,100 per subscriber. This

number is in line with numbers published in

the final BPL report from United Telecom

Council (UTC) Research and The Shpigler Group,

In November 2006,

the FCC decided

to classify

BPL-enabled

Internet access

services as

information

services.

By virtue ofbeing considered

information

services, BPL

services become

free from many,

if not all,

common carrier

regulations and

associated fees

and taxes.


16/20


which compares deployment costs for various

broadband technologies [36, 37]. See Figure 6.

It is also interesting to note that, even though

deploying BPL in rural areas could be less

expensive than deploying DSL, cable, or fiber, it

may still be prohibitively expensive per capita.

With this in mind, BPL operators may choose,

instead, to compete with DSL, cable, and other

service providers in suburban and urban areas

where some sort of broadband services already

exists. Ironically, this would defeat the main

reason that the FCC adopted BPL: to accelerate

the availability of broadband services in

underserved areas. Furthermore, prior experience

and research have shown that BPL service

needs to be either significantly better (e.g., have

higher user throughputs), cheaper, or both, to

be able to convince subscribers to change

existing services to BPL or to attract new

subscribers to this new technology.

With this in mind, BPL service penetration PBPLwould typically be some function of BPL service

cost CBPL , including CPE, installation and setup,

and a monthly service fee; the service costs of

existing broadband services Cexisting ; the available

data throughput of BPL RBPL ; and the data

throughput of existing services Rexisting [38]. Asimple formulation could be:

where is a weighting factor (e.g., 10 or 20)

that reflects the importance of performance

versus cost.

In this formulation, PBPL becomes null if its cost

and data rates are the same as those of existing

broadband services. Of course, this formulation

does not take into account the value that BPL

offers by providing smart-grid services.

(Assessing the potential revenue and savings

from BPL smart grid services would be the

subject of another study.)

CONCLUSIONS

Even though the importance and directsocioeconomic impact of access to broadbandservices are well understood, currently only

4 percent of the Earths population has access

to some type of broadband services, typically

via DSL or cable modem. BPL offers a new,

potentially powerful alternative means of

providing high-speed Internet services, VoIP, and

other broadband services to homes and

businesses by using existing MV and LV power

lines. Because roughly 60 percent of Earths

inhabitants have access to power lines, BPL couldplay a significant role in bridging the existing

digital divide. But the success of BPL, like

that of any new technology in its infancy,

depends on more than strong theoretical

results or successful field testing. It also depends

greatly on the appropriate business models and

deployment plans.

As the regulatory uncertainties and interference

issues surrounding BPL dissipate, and with the

success of many field trials and early commercial

deployments, the release of various standards,

and the growing availability of reasonably pricedstandardized and reliable equipment, the road

to BPL is becoming increasingly well paved

and broadband over power lines seems to be

well energized. Indeed, BPLs future looks

very bright!

ACKNOWLEDGMENTS

One of the authors, S. Rasoul Safavian, wouldlike to express his gratitude for usefuldiscussions with Professor Mohsen Kavehrad of

the Electrical Engineering Department at thePennsylvania State University, several staff

members of the Federal Communications

Commission, and David Shpigler of The

Shpigler Group.

AccessMethod

Wireless

DSL

Cable Modem

BPL

Satellite

FTTH

Deployment Cost per Subscriber ($)

$1,825

$1,408

$1,007

$900

$828

$800

0 400 800 1,200 1,600 2,000

Figure 6. Deployment Costs for

Different Access Technologies

PBPL = Min{100, Max{0, [(CexistingCBPL)

+[log2(RBPL) log2( Rexisting)]]}}

As the regulatory

uncertainties and

interference issues

surrounding

BPL dissipate, and

with the success of

many field trials and

early commercial

deployments,the release of

various standards,

and the growing

availability of

reasonably priced

standardized and

reliable equipment,

the road to BPL

is becoming

increasinglywell paved.


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TRADEMARKS

Amperion is a trademark of Amperion, Inc.

CURRENT Technologies is a registered

trademark of CURRENT Communications

Group, LLC.

EarthLink is a registered trademark of EarthLink,

Inc.

HomePlug is a registered trademark of the

HomePlug Powerline Alliance.

P1675 is a trademark of the IEEE.

REFERENCES

[1] T. Farrar, ATC: The Future of Mobile SatelliteServices? TMF Associates report, publishedFebruary 2006/updated August 2006(http://www.tmfassociates.com/ATC.html).

[2] Information about and images of the Earthin a website by The Ozone Hole, Inc.(http://www.solcomhouse.com/earth.html).

[3] C. Howson, Technology Outlook forBroadband & Mobile Networks, BROADWANWorkshop, Cuenca, Spain, November 2005(http://www.telenor.no/broadwan/WorkshopNovember2005/Howson_BROADWAN_Cuenca_Workshop.pdf).

[4] T.L. Friedman, The Lexus and The Olive Tree:Understanding Globalization, Farrar, Strausand Giroux, 2000.

[5] Promoting Innovation and Competitiveness President Bushs Technology Agenda(http://www.whitehouse.gov/infocus/technology/).

[6] United Power Line Council (UPLC) BPL

Deployments Map (http://www.uplc.utc.org/file_depot/0-10000000/0 10000/7966/conman/BPL+Map+12_12.pdf).

[7] Open PLC European Research Alliance (OPERA)(http://www.ist-opera.org/).

[8] IEEE BPL Study Group and Working Groupmeeting information re Standardizationof Broadband Over Power Line Technologies(http://grouper.ieee.org/groups/bpl/index.html).

[9] Universal Powerline Association (UPA)(http://www.upaplc.com/page_viewer.asp?category=Home&sid=2).

[10] HomePlug Powerline Alliance(http://www.homeplug.org/en/index.asp).

[11] S. Houle, Building the Smart Grid TXU BPLInitiative (http://www.gulfcoastpower.org/default/2-06meeting-houle-austin.pdf).

[12] J.M. Bradbury, Broadband over Power Linesa Foundation for the Utility of the Future,Energy Summit 2006 (http://www.enrg.lsu.edu/conferences/energysummit2006/

Jay_Bradbury_2.pdf).

[13] M. Gotz, M. Rapp, and K. Dostert,Power Line Channel Characteristics andTheir Effect on Communication System Design,IEEE Communications Magazine, Vol. 42, No. 4,April 2004, pp. 78-86.

[14] H. Ferreira, O. Hooijen, and H. Grove,Power Line Communications: An Overview,IEEE Conference Proceedings for AFRICON 1996,Stellenbosch, South Africa, September 1996,Vol. 2, pp. 558563.

[15] M. Zimmermann and K. Dostert,A Multipath Model for the Powerline Channel,IEEE Transactions on Communications, Vol. 50,No. 4, April 2002, pp. 553559.

[16] M. Zimmermann and K. Dostert, Analysis andModeling of Impulsive Noise in Broad-bandPowerline Communications, IEEE Transactionson Electromagnetic Compatibility, Vol. 44, No. 1,February 2002, pp. 249258.

[17] J.R. Carson, Wave Propagation in OverheadWires with Ground Return, Bell SystemsTechnical Journal, Vol. 5, May 1926, pp. 539554.

[18] M. DAmore and M.S. Sarto, A NewFormulation of Lossy Ground Return Parametersfor Transient Analysis of Multi-Conductor

Dissipative Lines, IEEE Transactions on PowerDelivery, Vol. 12, No. 1, January 1997, pp. 303314.

[19] P. Amirshahi and M. Kavehrad, High-FrequencyCharacteristics of Overhead MulticonductorPower Lines for Broadband Communications,IEEE Journal on Selected Areas in Communications,Vol. 24, No. 7, July 2006, pp. 12921303.

[20] P. Amirshahi and M. Kavehrad, TransmissionChannel Model and Capacity of Overhead Multi-Conductor Medium-Voltage Power-Lines forBroadband Communications, IEEE Proceedingsof CCNC 2005, Las Vegas, NV, January 2005,pp. 354358.

[21] J.J. Lee, Measurements of the Communications

Environment in Medium Voltage PowerDistribution Lines for Wideband Power LineCommunications, Proceedings of ISPLC 2004,Zaragoza, Spain, pp. 6974.

[22] M. Zhang and W. Lauber, Evaluation of theInterference Potential of PLC Systems,Proceedings of the 2006 IEEE InternationalSymposium on Power Line Communications andits Applications (ISPLC-2006), Orlando, FL,March 2006, pp. 296301.

[23] P.S. Henry, Interference Characteristics ofBroadband Power Line CommunicationSystems Using Aerial Medium Voltage Wires,IEEE Communications Magazine, Vol. 43, No. 4,April 2005, pp. 9298.

[24] R.G. Olsen, Technical Considerations forBroadband Powerline (BPL) Communication,Proceedings of 15th International Zurich Symposiumon Electromagnetic Compatibility (EMC Zurich 05),Zurich, February 2005.

[25] L.S. Cohen, J.W. de Graaf, A. Light, and F. Sabath,The Measurement of Broadband over PowerLine Emissions, Proceedings of the 2005 IEEEInternational Symposium on ElectromagneticCompatibility (EMC 2005), Chicago, IL, Vol. 3,pp. 988991.


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[26] W. Liu, H. Widmer, and P. Raffin, BroadbandPLC Access Systems and Field Deploymentin European Power Line Networks,IEEE Communications Magazine, Vol. 41, No. 5,May 2003, pp. 114118.

[27] B. Malowanchuk, Broadband over Power Line(BPL) Interference: Fact or Fiction? La Revue desRadioamateurs Canadiens (Canadas Amateur Radio

Magazine), July & August 2004, pp. 3944(http://www.arrl.org/tis/info/HTML/plc/files/Barry.pdf).

[28] H. Dai and H.V. Poor, Advanced SignalProcessing for Power Line Communications,IEEE Communications Magazine, Vol. 41, No. 5,May 2003, pp. 100107.

[29] Corridor Systems, Inc.(http://www.corridor.biz/).

[30] ARRL comments on ET 03-104, the FCC Noticeof Inquiry on Broadband Over Power Line(http://www.arrl.org/announce/regulatory/et03-104).

[31] NTIA Report 04-413, Potential Interference fromBroadband over Power Line (BPL) Systems toFederal Government Radio Communicationsat 1.7 - 80 MHz Phase 1 Study, Volume I,

NTIA, U.S. Department of Commerce, April 2004(http://www.ntia.doc.gov/ntiahome/fccfilings/2004/bpl/).

[32] FCC 04-29, Notice of Proposed Rule Making,in the Matter of Carrier Current Systems,including Broadband over Power Line Systemsand Amendment of Part 15 regarding newrequirements and measurement guidelines forAccess Broadband over Power Line Systems,February 2004 (http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-29A1.pdf).

[33] FCC Report and Order 04-245, ET Dockets 04-37and 03-104, in the Matter of Amendment ofPart 15 regarding new requirements andmeasurement guidelines for Access Broadband

over Power Line Systems and Carrier CurrentSystems, including Broadband over Power LineSystems, October 2004(http://www.hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-245A1.doc).

[34] W.D. Gardner, FCC Endorses Broadbandover Powerline, TechWeb Technology News,November 3, 2006 (http://www.techweb.com/wire/mobile/193501695).

[35] FCC 06-56, Second Report and Order andMemorandum Opinion and Order, ET DocketNo. 04-295 and RM-10865, in the Matter ofCommunications Assistance for Law EnforcementAct and Broadband Access and Services,released May 2006/finalized December 2006.

[36] Opportunities in Broadband over Power Line,Report by The Shpigler Group and UTC Research,

July 2004 (http://www.igigroup.com/st/pages/utc.bopl.html).

[37] David Shpigler, private communication,December 2006.

[38] P.A. Brown, Identifying Some Techno-Economic Criteria in PLC/BPL Applicationsand Commercialization, Proceedings of the9th International Symposium on Power LineCommunications (ISPLC) and its Applications,Vancouver, Canada, April 2005, pp. 234239.

BIOGRAPHIES

Lee Lushbaugh, principal vicepresident, Bechtel Corporation,and general manager, Tele-

communications, Americas,provides day-to-day oversightfor both business developmentand operational activitiesin the region. During 2006,the regional staff reachedapproximately 1,500 employees

working in 35 markets across the continental UnitedStates. Previously, Lee has served as director ofengineering and as the program director of severalnationwide wireless programs and a fiber deploymentprogram. He joined Bechtel Telecommunications in1996 as vice president/manager of engineering and wasthe initial developer of its engineering department.

Lee joined Bechtel Corporation in 1974 and, before

joining Bechtel Telecommunications, held bothfunctional and operational roles in the fossil power andnuclear business lines, including the plant design, civil,and mechanical engineering disciplines.

Lee received a BS in Mechanical Engineering fromthe University of Maryland. He is a RegisteredProfessional Engineer in various states, a member of theAmerican Society of Mechanical Engineers, and a SixSigma Champion.

Rasoul Safavian brings morethan 15 years of experiencein the wired and wirelesscommunications industry tohis position as BechtelTelecommunications vice

president of Technology,Americas Regional BusinessUnit. He is charged withestablishing and maintaining

the overall technical vision for Bechtels Americanmarkets and providing guidance and direction toits specific technological activities. In fulfillingthis responsibility, he is well served by hisbackground in cellular/PCS, fixed microwave, satellitecommunications, wireless local loops, and fixednetworks; his working experience with major 2G, 2.5G,3G, and 4G technologies; his exposure to the leadingfacets of technology development as well as itsfinancial, business, and risk factors; and his extensiveacademic, teaching, and research experience.

Before joining Bechtel in June 2005, Dr. Safavian

oversaw advanced technology research anddevelopment activities, first as vice president of theAdvanced Technology Group at Wireless Facilities, Inc.,then as chief technical officer and vice president ofengineering at GCB Services. Earlier, over an 8-yearperiod at LCC International, Inc., he progressedthrough several positions. Initially, as principalengineer at LCCs Wireless Institute, he was in chargeof CDMA-related programs and activities. Next, aslead systems engineer/senior principal engineer,


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he provided nationwide technical guidance for LCCsXM satellite radio project. Then, as senior technicalmanager/senior consultant, he assisted key clients withthe design, deployment, optimization, and operation of3G wireless networks.

Dr. Safavian has spoken at numerous conferencesand industry events and has been publishedextensively, including technical papers in theprevious three issues of the Bechtel TelecommunicationsTechnical Journal.

Dr. Safavian is quite familiar with the Electrical

Engineering departments of four universities: TheGeorge Washington University, where he has been anadjunct professor for several years; The PennsylvaniaState University, where he is an affiliated facultymember; Purdue University, where he received hisPhD in Electrical Engineering, was a graduate researchassistant, and was later a member of the visiting faculty;and the University of Kansas, where he received bothhis BS and MS degrees in Electrical Engineering andwas a teaching and a research assistant. He is a seniormember of the IEEE and a past official reviewer ofvarious transactions and journals.


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broadband over power

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