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PLC: Electrifying Communications

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VoicenData Bureau
New Update

A

wise man once said, progress is the path from the primitive, via

the complicated to the simple.
Thanks to Power-line

Communications (PLC), telephoning via the electricity supply

network from any power supply socket to any telephone in the

world is possible now.

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"I need to send some

urgent e-mails. Where can I connect my PC to the network?"

Shahid Ali asked the receptionist shortly after his arrival at

his company’s freshly opened branch office. "I know that

when the building was being renovated it was planned to have a

communication socket in every room, but I cannot find one!"

The receptionist’s radiant smile quickly soothed the new

colleague, but her answer almost knocked him for six.

"Every power socket in this building is a communications

connection. And you not only have Internet access, you can

telephone as well."

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Difficulties

Overcome

This

scenario could occur in every office building or household in

the not too distant future. Since what was once thought to be

impossible has become a reality: Telephoning via the electricity

supply network from any power supply socket to any telephone in

the world. For a long time even the experts doubted this

development. The objections against a universal network for

electricity supply and communications were overwhelming. The

electricity supply network is considered to be an extremely

demanding transmission channel. Since the signal, which is fed

into the network suffers attenuation on the long path from the

transmitter to the receiver. The greater the distance, the

greater the attenuation. Over and above this the electromagnetic

compatibility of PLC is regarded as a real challenge.

Interference must be avoided. Thus certain frequency bands are

disallowed for wire bound transmission procedures such as PLC,

depending on national regulations.

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In principle, it is

possible today for every electricity socket to be turned into an

interface for a PC printer, telephone or other communications

devices. And solutions are available today that offer

communication over the electricity supply network. Vendors claim

that the transmission over the electricity supply network using

PLC is so good that for the first time voice traffic and high

speed data can be transmitted right from the transformer station

to every socket in the building.

The success potential of

the PLC approach does not, however, lie just in the technology

but also in the new services which can be implemented using it.

All devices that are powered from the mains supply are connected

to the same network. Hence diverse new service and applications

come to mind which will combine communications and IT devices

such as the telephone and the PC with traditional electrical

devices. Examples range from facility management, credit card

verification, the control of heating, air conditioning or

ventilation systems, through to electronic newspapers and tele-conferencing.

The broadband PLC system with which Ali’s company will soon be

equipped, permits access to the network from every room in the

building without the need to lay new cables.

The system functions as

follows: In the electricity supply company’s transformer

station, a PLC modem modulates the high frequency signal of the

telecommunications backbone network onto the low-voltage local

electricity supply network over which it is carried into the

building. According to vendors data rates of more than 1 Mbit/s

have already been achieved. This is 20 times the speed of ISDN,

which is 64 Kbit/s. It is important to note that the PLC

solution not only covers the path from the transformer station

to the building but can also connect the mains supply circuits

within the building. Every power socket in the building is thus

connected to the communications network. This brings tremendous

advantages, for example, for a company that needs to install a

local area network in an old building. After all, the in-house

PLC local area network for networking computers and peripheral

equipment can easily be based on the existing mains cabling.

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The electricity supply

cables permit solutions with which transmission rates of up to

10 Mbit/s can be achieved. Every PLC modem provides two

transparent interfaces for TCP/IP so that the system can easily

be integrated into existing computer networks.

It is important to ensure

that the further development of PLC does nor result in

proprietary solutions. Rather, an open power-line platform must

be built up with interfaces, which are strictly defined. The

services that are to be offered over the low-voltage power

supply network are then "mounted" on this open

platform. Solutions should also take investment costs into

account. The interfaces of the PLC are oriented to existing

technologies and standards. PLC customers will get an

"Always On" service. It is for this reason that

packet-oriented solutions as used in the Internet, for example,

are used. Equally, the interfaces must also be the customary

ones (Ethernet, USB, etc.). It thus makes sense for PLC

solutions to be created through close cooperation between

electricity supply companies, telecommunications suppliers and

service providers. Then in future there will be: One network for

everything.

Courtesy:

Ascom

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