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).
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.
Evolution of the Internet 1945 1995 Memex Conceived 1945 WWW Created 1989 Mosaic Created 1993 A Mathematical Theory of Communication 1948 Packet Switching Invented 1964 Silicon Chip 1958 First Vast Computer Network Envisioned 1962 ARPANET 1969 TCP/IP Created 1972 Internet Named and Goes TCP/IP 1984 Hypertext Invented 1965 Age of eCommerce Begins 1995
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
High speed Internet Access
Share market dealing & personal banking
News, travel & leisure information
Chatrooms & newsgroups
E-mail & instant messaging
Personal websites and online magazines
Educational materials & research resources
Work at home
Internet radio & webcast concerts
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
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.
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
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
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."
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 .
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
Choose modulation schemes robust enough to work in hostile
– Direct Sequence Spread Spectrum (DSSS)
– Orthogonal Frequency Division Multiplexing (OFDM)
– Single Carrier
OFDM Spread Spectrum Techniques (FH and DS) Single Carrier Spectral Efficiency Good Poor Moderate Robustness Against Channel Distortions Excellent Not Good Good Robustness Against Impulsive Noise Fair Fair Good Ability to adapt to channel changes Excellent Fair Good Implementation Costs (Equalizers, etc.) Fair Poor Poor (Equalizers required)
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.
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.
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.