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Powerline Communication 1. INTRODUCTION Connecting to the Internet is a fact of life for business, government, and most households. The lure of e- commerce, video on demand, and e-mail has brought 60 million people to the Internet. Once they get to the Internet, they find out what it’s really like. That includes long waits for popular sites, substantial waits for secure sites, and horrible video quality over the web. Telephone companies have offered high bandwidth lines for many years. For the most part, the cost of these lines and the equipment needed to access them has limited their usefulness to large businesses. The lone exception has been ISDN (Integrated Services Digital Network) which has won over some residential customers. ISDN offers fast Internet access (128k) at a relatively low cost. Here the solution is Powerline communications (or PLC). Powerline communications is a rapidly evolving market that utilizes electricity power lines for the high-speed transmission of data and voice services. None of the available Internet access services offer the right balance of cost, convenience, and speed. Digital Powerline technology could change all that. It gives customers high speed Internet access through electrical networks. Lower costs are achieved because the service is Dept. of AE&I 1 SJCET
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Page 1: Powerline Communication

Powerline Communication

1. INTRODUCTION

Connecting to the Internet is a fact of life for business, government, and

most households. The lure of e-commerce, video on demand, and e-mail has brought 60

million people to the Internet. Once they get to the Internet, they find out what it’s

really like. That includes long waits for popular sites, substantial waits for secure sites,

and horrible video quality over the web.

Telephone companies have offered high bandwidth lines for many years.

For the most part, the cost of these lines and the equipment needed to access them has

limited their usefulness to large businesses. The lone exception has been ISDN

(Integrated Services Digital Network) which has won over some residential customers.

ISDN offers fast Internet access (128k) at a relatively low cost.

Here the solution is Powerline communications (or PLC). Powerline

communications is a rapidly evolving market that utilizes electricity power lines for the

high-speed transmission of data and voice services.

None of the available Internet access services offer the right balance of

cost, convenience, and speed. Digital Powerline technology could change all that. It

gives customers high speed Internet access through electrical networks. Lower costs are

achieved because the service is implemented on standard electrical lines. The service is

also convenient

because it’s already in your home. Internet access through Digital Powerline would be

at (at least) 1Mbps, 20 times faster than a standard phone/modem connection.

2. HISTORY OF PLC

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The technology has roots going back to the 1940s.It has been used by

power utilities for simple telemetering and control of electrical equipment in their

networks.

What is new is the integration of activities outside the building with

those inside the building at a much higher bandwidth, 2.5 mbps or higher.

3. OVERVIEW OF TECHNOLOGY

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PLC works by transmitting high frequency data signals through the same

power cable network used for carrying electricity power to household users. Such signal

cannot pass through a transformer. This requires devices that combine the voice and

data signals with the low-voltage supply current in the local transformer stations. The

signal makes its way to neighborhoods and customers who could access either it

wirelessly, through utility poles.

Digital Powerline use a network, known as a High Frequency

Conditioned Power Network (HFCPN), to transmit data and electrical signals. A

HFCPN uses a series of Conditioning Units (CU) to filter those separate signals. The

CU sends electricity to the outlets in the home and data signals to a communication

module or "service unit". The service unit provides multiple channels for data, voice,

etc. Base station servers at local electricity substations connect to the Internet via fiber

or broadband coaxial cable. The end result is similar to a neighborhood local area

network.

3.1 THE SERVER:

The Digital Powerline base station is a standard rack mountable system

designed specifically for current street electricity cabinets. Typically, one street cabinet

contains twelve base station units, each capable of communicating over 1 of 40 possible

radio channels. These units connect to the public telecommunications network at E1 or

T1 (*see appendix D) speeds over some broadband service.

Several options, with different costs, can provide broadband Internet

service to each base station. The simplest solution is connecting leased lines to each

substation. This solution is potentially quite costly because of the number of lines

involved. A wireless system has also been suggested to connect base stations to the

Internet. This option reduces local loop fees, but increases hardware costs. Another

alternative involves running high bandwidth lines, along side electric lines, to

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substations. These lines could be fiber (*See appendix C), ATM, or broadband coaxial

cable. This option avoids local loop fees, but is beset by equipment fees. The actual

deployment of Digital Powerline will probably involve a mix of these alternatives,

optimized for cost efficiency in different areas and with different service providers.

These base stations typically serve approximately 50 customers,

providing over 20 MHz of usable spectrum to near end customers and between 6 and 10

MHz of useable spectrum to far end customers. The server operates via IP to create a

LAN type environment for each local service area.

3.2 THE HFCPN CONDITIONING UNIT:

The conditioning Unit (CU) for the Digital Powerline Network is placed

near the electric meter at each customer’s home. The CU uses band pass filters to

segregate the electricity and data signals, which facilitate the link between a customer’s

premise and an electricity substation.

The CU contains three coupling ports. The device receives aggregate

input from its Network Port (NP). This aggregate input passes through a high pass filter.

Filtering allows data signals to pass to a Communications Distribution Port (CDP) and a

low pass filter sends electric signals to the Electricity Distribution Port (EDP).

The 50 Hz signal flows from the low pass filter, out of the EDP and to

the electricity meter. The low pass filter also serves to attenuate extraneous noise

generated by electrical appliances at the customer premises. Left unconditioned, the

aggregation of this extraneous noise from multiple homes would cause significant

distortion in the network.

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Fig:1 -HFCPN Conditioning Unit

The high pass filter facilitates two way data traffic to and from the

customer premise. Data signals flow through the CDP to the customer’s service unit via

standard coaxial cable.

3.3 SERVICE UNIT:

The service unit is a wall or table mountable multi-purpose data

communications box. The unit facilitates data connections via BNC connectors to cable

modems and telephone connections via standard line termination jacks.

Fig:2-Service Unit

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The service unit provides its own line power for ringing and contains a

battery backup in case of power outage. Alternative Differential Pulse Code Modulation

(ADPCM) is used for speech sampling. Because Digital Powerline allows for the

termination of multiple radio signals at the customer premises, the service unit can

facilitate various Customer Premises Equipment (CPE) simultaneously. In a manner

similar to ISDN, data (computers) and voice (telephones) devices can coexist without

interfering with each other.

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4. CASE STUDY

4.1 Powerline Trials: Seymour Park Primary School:-

Fig:3-Stanley Rd. Distribution Grid

Digital Powerline technology was first tested in a public setting at the Seymour Park

Primary School in Manchester, UK. Twelve PCs were connected to a single Digital

Powerline outlet. Dedicated high-speed access to the Internet turned out to be a great

success in the eyes of students and teachers. Nortel’s Digital Powerline web site quotes

Seymour Head teacher, Jenny Dunn; "The high speed connection really lets us take

advantage of the educational potential of the Internet. With a normal connection the

children could lose interest waiting for pages to download. The new system means

information arrives virtually instantaneously, thereby maximizing teaching time and

keeping children on task. This set is amazingly flexible in educational terms, and not

only gives us the additional medium with which to improve standards, but prepares us

for the National Grid for Learning."

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4.2 Powerline Trials: Stanley Road

Following the success at Seymour Park, a more comprehensive trial was

initiated at the Stanley Road electricity substation, also located in Manchester. The crux

of this trial was to test the limits of Powerline technology and make sure that it could

meet industry standards even in worst case scenarios.

The Stanley Road substation was set up to use two distributors to serve

two distinct neighborhoods. Northumberland Close is located 350 meters from the

substation and Seymour Close is located 600 meters from the substation. Fifteen users

were chosen between the two neighborhoods to participate in the pilot program. They

received various data and telephone services as well as remote metering/information

services.

Unfortunately, the results of the trial are unobtainable. Nortel and

Nor.Web claim that the results of this trial and similar trials in the United States are

being protected for competitive reasons. The only indication of the trial’s success is a

subjective quote from Nor.Web. The quote states that "results produced over this period

have now proved conclusively that Nor.Web’s technology provides a commercially

viable alternative to established means of telecommunications delivery to customer

premises."

5. APPLICATION AREAS OFFERED BY PLC:

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PLC offers end-users a broad spectrum of applications and services

including broadband Internet access, voice over IP, multimedia services,

telecommunication, home automation and energy management(near energy services).

Powerline offers the opportunity for the PC to be integrated into the household as never

before. As part of the household power grid, PCs could easily be programmed to turn

off lights and control security devices.

5.1 Powerline telecommunication:

Powerline telecommunications is a rapidly evolving market that utilizes

electricity power lines for the high speed transmission of data and voice services. The

especially exciting thing about the potential for PLT is that it holds the promise of

solving the underlying structural problem confronting the local access market today.

PLT can provide the holy-grail of a much needed, highly elusive, alternative source of

ubiquitous local loops other than the incumbent telco operator, something we sadly have

yet to see happen on a sufficient scale and scope. Indeed, what make PLT so attractive

from a public policy point of view are the facts that:

The power grid is ubiquitous; it constitutes an existing network infrastructure to

billions of private consumers and businesses

The power grid offers last-mile conductivity

The power grid supports information based services with strong growth

potential.

5.2 Home Automation:

The Home Plug Powerline Alliance (HPA), a U.S. consortium of 90

members, including such high-tech giants as Cisco, Intel, Motorola, and Hewlett-

Packard is working on technology to link appliances such as TVs, computers and

cookers via the home electrical system.

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Appliance makers like Samsung Electronics Co. have been solidifying

cooperation with their technology partners to enable them to market Internet-

controllable home appliances this year. Samsung plans to set up a “Dream LG” site on

its homepage to advertise its Internet-enabled products to potential customers.

5.3 Internet access:

Last December Intellon announced its PowerPacketTM Powerline

networking chipset, the first product certified as compliant with the HPA’s 1.0

Specification introduced earlier that year. The chipset allows users to access the Internet

and connect computers and other devices at speeds up to 14 mbps by simply plugging

into power outlets throughout a home or small office.

5.4 Power management (near energy services):

Near energy services are defined as energy services with in the confines

of current business which ads new forms, features and scales. Examples are remote

billing, remote metering, demand side e management distribution automation and

remote control of supply. Advantages of such system for utilities lie in their potential

for cost cutting and improving customer loyalty.

6. POTENTIAL ADVANTAGES OF DIGITAL

POWERLINE COMMUNICATION

This telecommunications model has multiple advantages over others

including speed, an established local loop, and dedicated connections. These advantages

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make Digital Powerline technology an attractive alternative for telecommunications

systems.

In the Digital Powerline model, small LANs are created; they terminate

at each local electricity substation. These LANs will share a T1/E1 connection to the

Internet, similar to a corporation leasing a T1 line. Individual users should experience

tremendous speed increases over conventional 28.8kbs or 56kps dialup connections,

even at peak usage.

Another inherent advantage to the Digital Powerline model is the fact

that it works well over the existing electric power infrastructure (at least in the UK, see

the Limitations section below). Only the substation server equipment and customer

conditioning/service units need to be installed in order to establish a Digital Powerline

network.

Dedicated, multipurpose communication lines make the Digital

Powerline model an attractive option for the information age. Wide bandwidth and

frequency division multiplexing allow for multiple lines to a single household. Ideally,

an entire family could utilize their own communication devices simultaneously, whether

telephone or PC, without interrupting one another.

Powerline carry signals for long distances without requiring

regeneration. Their near light speed propagation makes them very powerful for fast

delivery of video and audio data. There is no topology limitation for power lines.

High transmission rate, right now 3 mbps in uploading and downloading.

The data transmission rate is expected up to 200 mbps in the future by improving the

PLC chip.

Permanent on-line connection with the potential for lower charges. No

need for complicated wiring and additional installations. Move your computers and

appliances where you want. Secure data-encryption. Lower investment costs compared

to those envisaged for other broadband data access systems.

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7. Potential Extensions to Digital Powerline Technology:

There are many possible extensions to the Digital Powerline model.

Those mentioned in reviews and technical journals include "the wired home" and

remote customer information services. Since Digital Powerline creates a LAN type

environment by running IP, people could theoretically control all of the appliances in

their home from their PC or a remote device. Each home on the neighborhood LAN

would operate as a sub-network of the LAN and each electrical outlet could be treated

as a node on that sub-network.

The Nortel web site predicts, "It could also be feasible to have an

Internet address for every plug in the house, through which you could e-mail, for

example: ‘fridge@home’ and study the picture relayed by the video camera to see what

shopping you require; or you could remotely turn the lights off and the burglar alarm on

using your own password."

Remote services such as remote metering have already been tested under

this model and many more services are possible. Because the service provider can keep

track of electricity and bandwidth usage via the network, customers will also be able to

monitor their usage, reliably predict billing and keep an eye on household usage (i.e. the

teenager’s phone usage).

8. CURRENT LIMITATIONS OF DIGITAL POWERLINE

TECHNOLOGY

8.1 Electro-Magnetic Radiation Issues:

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Powerline solutions, like phone line solutions, are unintentional

radiators. Emissions can potentially cause interference with radio, television,

community antenna television, telephone and DSL services.

Second generation PLC technologies are using techniques like OFDM,

which substantially reduce the potential of interference to radio users, thanks to a

decrease in transmitted power spectral density. The OFDM modulation spreads the

signal over a very wide bandwidth, thus reducing the amount on power injected at a

single frequency. Field trials of PLC technologies carried out during the last 2 years in

Europe (Spain, Italy, Germany), North America, South America (Chile, Brazil) and

Asia (Singapore) have shown that interference with radio users is no longer a problem

for PLC. The same technique explains why current PLC technology does not affect

other appliances in the home.

8.2 Addressing Issue:

As the number of users and devices connected to Power Lines increases

by orders of magnitude, it becomes clear that we cannot satisfy the demand using

IPv4/NAT, at least not without enormous administrative complexity. A much larger

address space is needed to provide end-to-end connectivity in a simple manner and to

allow new applications and services to work in a transparent manner.

Clearly, the solution of problem is with IPv6, or Next Generation

Internet Addresses (IPNG) unlimited address space of IPv6 is needed to provide end-to-

end connectivity and allow new applications and services to work in a transparent

manner across PLC networks at massive scale (imagine every power socket in Beijing

or Mumbai becoming an Internet access point!).

8.3 Security:

The transmission of data over a network that anybody has access to

could also pose a data security problem, however. Tapping the signal could allow

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somebody to eavesdrop on communications. Only data encryption eliminates that

problem.

8.4 Noise interference:

Power line networking is also vulnerable to interference from devices

connected to the power infrastructure, such as microwaves and computers.

This can be solved by either using repeaters or dynamic chang of

frequencies.

8.5 Regulatory and standardization issues:

Powerline's maximum access speed is shared with all users connected to

the same local network station. The more people that are simultaneously on the Internet,

the lower the speed obtained.

Several implementation issues have held back Digital Powerline in North

America and the UK. Respectively, the problems are the numbers of users per

transformer and the size and shape of light poles.

In North America, a transformer serves from 5 to 10 households while in

Europe a transformer serves 150 households. Digital Powerline signals cannot pass

through a transformer. Therefore, all electrical substation equipment needed for Digital

Powerline has to be located after the transformer. Since there are fewer households per

transformer in North America, predicted equipment costs are prohibitive. However, this

conclusion has been debated. Analysts suggest that 100% subscription rates are possible

in the US, and that at such rates Digital Powerline is profitable. Conventional wisdom

suggests that there is a way to make Digital Powerline profitable in North America,

whether it is through bundling a variety of services or higher fees.

Soon after the first trials of Digital Powerline in the UK, some

unanticipated problems arose. Certain radio frequencies were suddenly deluged with

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traffic, making it impossible to transmit on those frequencies. BBC, amateur radio, and

the UK’s emergency broadcasting service were affected. The apparent culprits were

standard light poles. Then it became clear that by pure chance British light poles were

the perfect size and shape to broadcast Digital Powerline signals. This situation posed

problems not just because of the frequencies involved but also because anyone could

listen in on the traffic. Nor.Web is addressing the problem by proposing to lease the

frequencies involved from their owners and offering amateur radio operators a new

frequency. Negotiations on this topic are currently taking place in London. The privacy

issue has not been fully addressed at this point, besides suggestions that all sensitive

information should be encrypted.

While the promise of Powerline Telecommunications is great, it is

important for everyone to understand that this technology is in its infancy and there are

several hurdles the Powerline industry is working hard to overcome to make PLT a true

close substitute to the existing incumbent public switched telephone network (PSTN) in

the United States. Specifically, the main weaknesses of PLT products and services are

that:

(a) They are still at the developmental stage;

(b) There is no significant installed customer base to date;

(c) And the distances that Powerline technology can cover are limited.

Moreover, the industry is working hard to resolve the complex issues of

standardization and interoperability.

9. THE MARKET OF DIGITAL POWER LINE

Trends in both the electric and telecommunications industry have lead to a

climate where Digital Powerline should be a big player. These trends include customer

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demand for affordable and high speed Internet access, deregulation of electrical utilities,

and the repercussions of a variety of telecommunications legislation.

Customers want cheaper, faster, and more reliable access to the Internet right

now. Not only can Digital Powerline provide that type of service, but it will be available

before other broadband access technologies. Therefore Digital Powerline has both a

time to market and cost advantage.

The utility industry is facing deregulation in North America, Europe, and some

parts of Asia. Deregulation means increased competition in the slow growing electricity

market with little protection for utilities. An unenviable position indeed. Consequently,

many utilities are actively seeking to diversify into other, more profitable, industries.

For many utilities telecommunications and Internet services have been a sensible

choice. That option can only become more popular as Digital Powerline matures.

Digital Powerline offers a deregulated utility several options and advantages. The

utility can either lease the rights to implement Digital Powerline on its electrical grid or

develop the technology itself. The advantages include the low cost of the local loop,

differentiating the utility from other utilities, and bundling a variety of services.

The most recent telecommunications act has tried to make it easier for all types

of telecommunications firms to sell local services and long distance services. However,

Regional Bells actually have control over local lines and charge other companies who

place calls on their lines. Many of the larger phone companies have sought to get

around these charges by building or leasing their own networks to connect to local

points. Digital Powerline is an existing network that fits those needs. Expect to see

smaller telecommunications companies partnering with electrical utilities to provide

alternative local phone service.

9.1 Who is testing or has tested the technology?

PLC abroad:

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Proof that the PLC concept works in practice was furnished by a series of

field trials by Main.net of Israel, ASCOM of Switzerland and some other companies in

16 European countries from Portugal to Scandinavia, as well as in Hong Kong, Korea,

India, Singapore and the Americas. These trials fulfilled all expectations of reliability,

functionality and the practical applications of Powerline communications. The first

installations are now already up and running or about to go live.

Users in Germany include the electricity companies RWE Energie Essen

and EnBW Energie Baden-Württemberg, while in Spain the energy and telecoms group

Endesa uses PLC technology. Lina.Net of Iceland, a subsidiary of Reykjavik Energy,

has recently begun introducing PLC technology with the declared objective of providing

private households with fast Internet access over the power grid rather than the

telephone network. In Sweden SYDKRAFT, one of the leading energy providers in

Scandinavia uses PLC for bridging the last mile as well as for networking inside

buildings.

PLC in USA:

New York-based Ambient - which will partner with Cisco, perhaps the

technology's largest supporter, and Bechtel on future projects - is working with the

utility Consolidated Edison of New York and Southern Telecom of Atlanta, a subsidiary

of Southern Co., a leading energy company to expand its testing to several hundred

homes. Results indicated that high frequency data transmissions could be transmitted

and received over distances of more than half a mile, with minimal signal loss. In recent

months, Ambient has achieved throughput speeds in excess of 20 mbps, and

connectivity over distances of 1.5 miles. Up to 200 users can be supported on a single

distribution circuit. Pricing for the systems is not yet available. Ambient expects to go

fully commercial with its systems by first quarter 2003.

Powerline Technologies in Reston, Virginia, is trying out its system with

two utilities in the East and one in the Midwest. Earlier last year, the company finished

initial PLT tests in suburban Atlanta, where a handful of households accessed the Net

through a specially designed modem that can hit speeds greater than 1.5 mbps.

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Owing to recent advances for PLC in Europe, and the efforts of a handful

of U.S. PLC vendors – including one backed by American Electric Power (AEP), PLC

is closer to being a commercial reality in the U.S. than ever before. Beta tests scheduled

by each of these firms over the next 12 months will be crucial to resolving outstanding

technical hurdles, standardizing equipment and deployment techniques, and building

interest and partnerships with utilities.

10. CONCLUSION

Digital Powerline technology is an exciting alternative to connecting to

the Internet via phone and modem. Though this technology is not commercially

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available yet, it should be available before other broadband technologies due to the

relatively low cost of its local loop. Moreover, its high speeds will provide Internet

access, video on demand, local phone, and long distance phone services to customers.

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11. REFERENCES

1.www.powerlineworld.com/powerlineintro.html

2. www.powerlinecommunications.net/

3. www.powerline-plc.com

4. www.powerline.com

5. O’Neal Jr., J.B. (1986) "The residential power circuit as a

communication medium," IEEE

Trans. on Consumer Electronics, vol.

CE-32, No. 3, pp. 567-577. 

6. Malek, J.A. & Engstorm, J.R. (1976)

"R.F. impedance of United States

and European power lines," IEEE

Trans. on Elec. Comp., vol. EMC-

18, pp. 36-38. 

7. www.google.com

8. www.wikipedia.com

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