Broadband Over Power Lines

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Introduction

• Broadband over Power Line (BPL) is a technology that allows Internet data to be transmitted over utility power lines. (BPL is also sometimes called Power-line Communications or PLC.)

• No phone, cable or satellite connection is required. BPL operates at speeds similar to those of digital subscriber line (DSL).

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Introduction• BPL works by modulating high-frequency radio

waves with the digital signals from the Internet using OFDM(Orthogonal frequency-division multiplexing ).

• All power line communications systems operate by impressing a modulated carrier signal on the wiring system.

• A BPL subscriber installs a modem that plugs into an ordinary wall outlet and pays a subscription fee similar to those paid for other types of Internet service.

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Evolution of the Internet

1945 1995

Memex Conceived

1945

WWWCreated

1989

MosaicCreated

1993

A Mathematical

Theory of Communication

1948

Packet Switching Invented

1964

SiliconChip1958

First Vast ComputerNetwork

Envisioned1962

ARPANET1969

TCP/IPCreated

1972

InternetNamed

and Goes

TCP/IP1984

HypertextInvented

1965

Age ofeCommerce

Begins1995

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Internet Growth Trends• 1977: 111 hosts on Internet• 1981: 213 hosts• 1983: 562 hosts• 1984: 1,000 hosts• 1986: 5,000 hosts• 1987: 10,000 hosts• 1989: 100,000 hosts• 1992: 1,000,000 hosts• 2001: 150 – 175 million hosts• 2002: over 200 million hosts• By 2010, about 80% of the planet will be on the Internet

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Internet Services• High speed Internet Access• Video-on-Demand• Interactive Games• Share market dealing & personal banking• News, travel & leisure information• Music/Movie Download• Chatrooms & newsgroups• E-mail & instant messaging• Personal websites and online magazines• Educational materials & research resources• Tele-medicine• Work at home• Internet radio & webcast concerts

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Types Of Internet Connections

Broadband Technologies

Wireless

3G Mobile

Wireline

Wi-Fi (Wireless Fidelity)

LMDS & MMDS

FSO (Free Space Optics)

Satellite

DSL (Digital Sub’s Line)

Cable Modem

Optical Fibre Technologies

PLC (Power Line Communication)

WiMAX

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Why BPL?

Like phone companies, power companies also have lines strung all over the world. The difference is that they have power lines in a lot more places than phone companies have fiber optics. This makes power lines an obvious vehicle for providing Internet to places where fiber optics haven't reached.

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• Key Architectural Choices For BPL System

Bypass Transformer or Pierce Transformer? (MV to LV Conversion)•Bypassing transformer allows lower and more predictable signal loss, piercing requires no equipment

Signal Repetition• Regenerating data packets at various points allows greater reach at the expense of lower bandwidth and greater latency

Bandwidth and latency • Desired service offerings• Latency sensitive applications – voice and gaming

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The power flowing down high-voltage lines is between 155,000 to 765,000 volts. That amount of power is unsuitable for data transmission. It's too "noisy."

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• BPL bypasses this problem by avoiding high-voltage power lines all together. The system drops the data off of traditional fiber-optic lines downstream, onto the much more manageable 7,200 volts of medium-voltage power lines.

• Once dropped on the medium-voltage lines, the data can only travel so far before it degrades. To counter this, special devices are installed on the lines to act as repeaters.

• The CT Coupler allows the data on the line to bypass transformers.

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CT Bridge• The CT Bridge can also: – Manage symmetric data transmission to all the

electrical outlets in the customer's home or office ("Symmetric" means that uploads and downloads are transmitted at the same speed.)

– Support WiFi hot spots – Handle data routing – Manage subscriber information – Employ Dynamic Host Configuration Protocol (DHCP -

The protocol that allows the management and assignment of IP addresses on a network)

– Support security encryption of all transmissions

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CT Coupler

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Block Diagram

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Multiplexing

• Choose modulation schemes robust enough to work in hostile

• channels– Direct Sequence Spread Spectrum (DSSS)– Orthogonal Frequency Division Multiplexing (OFDM)– Single Carrier

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OFDM

SpreadSpectrum

Techniques (FHand DS)

Single Carrier

SpectralEfficiency Good Poor Moderate

RobustnessAgainst Channel

DistortionsExcellent Not Good Good

RobustnessAgainst

Impulsive NoiseFair Fair Good

Ability to adaptto channel

changesExcellent Fair Good

ImplementationCosts

(Equalizers,etc.)

Fair Poor Poor (Equalizersrequired)

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OFDM

• Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies.

• OFDM is used by powerline devices to extend Ethernet connections to other rooms in a home through its power wiring.

• This modulation is particularly important with such a noisy channel as electrical wiring.

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OFDM

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BPL MODEM• BPL modems use silicon

chipsets specially designed to handle the work load of pulling data out of an electric current.

• Using specially developed modulation techniques and adaptive algorithms, BPL modems are capable of handling powerline noise on a wide spectrum.

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• This is the general conceptual arrangement. • An Injector serves to provide the main data signal, a • Repeater serves to boost the signal at regular intervals due to line noise (similar to

Telephone T1 provisions), and an • Extractor serves to convey the data across the power transformer to the user(s) as

each transformer may feed power to several customers.

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System#1

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System#2

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System#3

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Applications

• Home networking• Automotive Uses

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References

• How stuff works• wikipidia

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