19-08-2014, 11:13 AM
BROADBAND OVER POWER LINES (BPL) FOR INDIAN TELECOM NETWORK PROJECT REPORT
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Abstract
In this paper various aspects of Broadband over Power line (BPL) in
Communication Network have been presented. The objective of this paper is to
highlight the BPL access technology in term of features, working, drawbacks,
deployment & future challenges, advantages and scope etc. BPL is now a growing
communication network technology which is quite fast hitting the competitive
market of broad band internet services in international telecom environment. In
addition, value added services like internet, voice, video applications etc. can also be
provided by BPL. Broad band over power lines may also be an effective viable
alternative for providing broadband in India. BPL technology has evolved rapidly
over the past few years. This has been possible due to world wide technological
developments and innovations on broadband over power lines
Introduction
The basic concept of this technology is that it offers high speed internet access to our
homes through the commonly accessible electrical paths, thus eliminating the need of
transmission of data over last mile through copper cable, short haul satellite systems,
optical fibre cable and wireless technologies such as Wi-Max, Wi-Fi etc.
In BPL technology, by combining the technological principles of Radio, wireless
networking, and modems, a mechanism has been created where one can plug in his
computer into any electrical outlet in his home to have instantaneous access to high speed
internet.
BPL uses the existing power grid infrastructure to provide high-speed, broadband Internet
access to homes and businesses. It is a new innovation based upon existing Power-Line
Communications (PLC) technology.
Background and current trends
Past BPL trends
Using power lines for telecommunication is very old and traditional, the term ‘Power
Line Carrier (PLC)’ has been used to refer to the use of electrical lines as a medium for
telecommunications.
Electric companies have deployed technologies such as SCADA (Supervisory Control
and Data Acquisition) over powerlines to perform simple command/control functions at
remote locations, such as sub-stations, using the electric transmissions lines as the
medium.
Electric company linesmen have also used the transmission lines by tapping the wire with
specialized radios for communicating with each other along through the line. On a
smaller scale, in-home intercom systems have been available for many years that use the
electric lines of the building to deliver audio data over the buildings electrical lines.
Current Status of BPL in the World
A number of foreign governments including USA, Australia, Austria, China, Finland,
Hong Kong, Hungary, Ireland, Italy, Korea, Japan, Netherlands, Poland, and Switzerland
are currently studying BPL technology or have permitted equipment trials. The outcomes
have shown mixed results and have led some administrations to ban BPL systems while
other administrations have allowed deployment under various conditions. A number of
administrations have suspended BPL trials pending international developments.
BPL deployment in India
Many rural residents and rural entrepreneurs in India don’t have access to DSL, FTTX,
Wireless, cable or other telephone medium. But mostly rural users in India have the
power lines. BPL technology is desirable option for those residents who want to get
broadband service. On the urban side, BPL may be used as another cheaper technology
for broadband services. BPL for broadband application may be considered an effective
and less costly solution as access network. The Broad Band Over Power Line
communication network technologies are new for Indian telecom network and will grow
extensively in near future
BPL Working
Broad band over power lines uses Power Line Communications (PLC) technology to
provide broad band internet access over ordinary power lines. A computer (or any other
device) would need only to plug a BPL “modem” into any outlet in an equipped building
to have high speed internet access in this case.
Internet signals using a fibre are dropped at medium voltage using a device called “ head
end” Once the data is dropped onto the medium voltage lines, it cannot travel too far
before it degrades. To overcome the problem of degradation of data before it reaches its
final customer destination in a healthy condition, special devices which act as repeaters
are installed on the medium voltage lines to amplify the data for further smooth
transmission. Finally internet is accessed by the end user using the plug in BPL modem
The function of BPL Modems
BPL modems use silicon chipsets specially designed to handle the workload of extracting
data out of an electric current. These modems are capable of handling power noise on a
wide spectrum. BPL modems are roughly the size of a comon power adapter and plugs
into a common wall socket and an ethernet cable running to computer finishes th
connection. There are various approaches available as far as last mile solution for BPL is
concerned. While some carry the signal in with electricity on the power line, others use
wireless links on the poles to send the data wirelessly into the homes. The BPL Modem
simply plugs into the wall and then into subscribers computer. These modems are capable
of speeds comparable to DSL or cable modems
OFDM Modulation
Orthogonal frequency-division multiplexing (OFDM) is a frequency multiplexing scheme
utilized as a digital multi carrier modulation method. In this technique, a large number o
closely spaced orthogonal sub carriers are used to carry data. The data is further divided
into several data cannels, one for each sub carrier. Each sub carrier is then modulated
with a conventional modulation scheme. Low symbol rate helps in maintaining total data
rates similar to conventional modulation schemes in the same range of bandwidth.
International Standardization
Interoperability that ensures that products from different vendors work well together to
create healthy competition in the marketplace, accelerate technical innovation and ensure
that customers get the best products at the best price has been one of the key issues
confronting the power line industry. Unfortunately, incompatible PHY/MAC standards
led to the creation of multiple industry alliances.
However, realizing that an altogether different approach was needed to address the issue
of interoperability in a comprehensive manner, a number of companies started an effort
inside ITU-T to create a unified G.hn networking standard that would bring three key
advantages
Issues, Challenges, Uncertainties and Drawbacks
Because of enormous variations in the physical characteristics of the electricity network
and virtual absence of international standards make the provisioning of service far from
being standard and a repeatable process. Besides, the amount of bandwidth that a BPL
system can provide compared to cable and wireless is in question. The issues being faced
by BPL is that power lines are inherently very noisy due to high energy that they carry.
Thus, turning on or off every time of any electrical device introduces a click into the line.
And this becomes quite predominant in case of enegy saving devices which introduce
quite noisy harmonics into the line. The system has thus to be designed to effetively deal
with these natural signalling disruptions.
Another major issue is signal strength and operating frequency. The system is expected to
use frequencies of 10 to 30 MHZ. Since power lines are unshielded and act as antennas
for the signals they carry, they have to interfere with short wave radio frequencies over
which BPL operates. And this interference becomes quite perceptible in cases where the
antennas are physically close to the power lines. However, this interference considerably
diminishes and is barely perceptible where the antennas are moderately separated from
the power network.
Conclusion, Recommendations and Future of BPL
In a Country like India where broad band penetration is extremely low and the costs of
laying down copper cable or providing short haul satellite for providing broad band for its
final leg of journey is very high, providing broad band over power lines holds a great
promise, provided issues relating to interference etc are sorted out. Even in advanced
Countries like USA, Europe etc., the larger issues of interference remain unaddressed
because of absence of stringent regulatory measures.Even in the absence of these
regulatory measures, BPL is gaining ground in these Countries despite strong protests
from those agencies which are vulnerable to interference because of BPL.
In our Country where serious financial constraints exist in terms of heavy investments to
be made for laying copper or installing satellite as a mode of final broad band
transmission, giving serious consideration and priority to BPL would be worthwhile,
while addressing other pertinent issues. Another great potential that BPL holds in future
is that it can be used as a backhaul for wireless communications, for instance by hanging
Wi-Fi access points or cell phone base stations on poles, thus allowing end users within a
certain range to connect with the equipment they already have.