13-07-2012, 09:44 AM
A NEW CONCEPT OF DIGITAL POWER LINE CARRIER COMMUNICATION FOR RURAL APPLICATIONS
[attachment=27514][attachment=27514]
ABSTRACT:
This paper describes cost-effective technique for the implementing rural wireless communication network by exploiting
remote RF concept and using existing power line as a physical medium. System level simulation consisting of power
line communication (PLC) transmitter and receiver has been carried out using Simulink 5.0 for noise evaluation. PLC
transmitter and receiver system is proposed using forward error correcting codes (FEC) and orthogonal frequency
division multiplexing (OFDM). It is shown that OFDM can be effectively utilised for base band signal modulation to
achieve both reduced EMI and improved signal-to-noise ratio. MATLAB simulation results indicating the probable
choice of carrier frequencies for PLC are presented.
INTRODUCTION:
There is a great disparity between the rural and urban masses in respect of access to Information and Communication
Technologies (ICTs) and thus leading to greater digital divide between them. Although numerous techniques have been
proposed to minimize this gap by effectively extending ICTs for rural applications to provide locally applicable content
and services but they prove to be expensive due to requirements of wireless infrastructure.
Recently, there has been resurgence of interest in using the existing power line for rural communication as
implementation of orthogonal frequency division multiplexing (OFDM) has become feasible due to technological
advancements. This has opened the gateway for achieving improved SNR (signal to noise ratio) using PLC and utilizing
the easily accessible rural power line as communication medium. Further, the cost of communication can be drastically
reduced by using remote RF in which the existing mobile wireless networks or traditional circuit switched networks of
urban areas can be extended to rural areas [1] [5] [6]. The suggested technique can thus provide cost effective solution
for implementation of wireless communication network without the need of exclusive wireless infrastructure. The PLC
can be used to extend the connection between a wireless radio base station and its antenna, in circuit switched networks
similar concept is implemented via VoIP (voice over IP). This extension can be to provide wireless services to new and
remote areas using radio equipment from an existing location.
This is achieved by transmitting the base band signal through already existing power line to remote rural areas, while
the remote RF is proposed to provide all the necessary backend support for communication network protocol
implementation and resource sharing. The signal processing techniques along with the OFDM offers better solution for
transmission of base band signal on power line. It has been shown that OFDM [9] is relatively immune to EMI, which
has been the prime driving force in studying its SNR performance for PLC [1]. Our simulation results indicate that
OFDM has greater potential for its use in PLC due to having reduced EMI and thus it has been used for generating base
band signal that is launched on power line.
BACKGROUND:
The application for the power line communication would be a system where the wiring would impose the main
expenses and a radio based system would not be feasible or too expensive. These prerequisites for power line
communication system would be met by high voltage or medium voltage power lines because power cables are up to
several tens/hundreds of kilometers and approaching even remote and rural areas. In addition to this PLC requires less
bandwidth.
The voice and data can be integrated using VoIP leading to development of a myriad of multimedia applications. The
international Telecommunications Union (ITU) emphasizes that VoIP can be used in certain areas without the need for
fixed line access [7]. For an example, it can be combined with wireless data technologies, such as Wi-Fi, to serve rural
and remote areas. It is also cheaper for consumers due to the tariff structure. However, when using VoIP, consumers
face a trade off between price and quality. The ITU suggest nevertheless that VoIP can be used to enhance access to
basic telecommunications. Hassan et al. argue that VoIP gives rise to low cost voice calls [8] and several calls can share
the same bandwidth. This is because there is no need for a dedicated communication line per each call as in Plain Old
Telephone Service (POTs).
MATLAB SIMULATION:
The base band signal from legacy networks to provide backend infrastructure support has been generated by Bernoulli
binary generator [3] block (512 kbps). Reed Solomon (RS) double error correcting (15,11) code has been used as FEC
code for base band signal to be sent to remote RF system. Coherent QPSK modulation and training (pseudo noise
sequence generation) blocks are used to provide input to OFDM symbol generation (IFFT add cyclic prefix block).
Training insertion block identifies training pattern in OFDM symbol and place them at predefined position in OFDM
symbol to facilitate training process. The parallel to serial (P/S) conversion block converts parallel data in to serial form
which is sent through power line using PLC coupler. The PLC noise [2] [10] is predominantly due to radio frequency
interference [4] [11] and impulsive noise. The development of PLC noise block is based on the assumption that
impulsive noise is generated because of switching of inductive loads. The switching inductive loads on the power line
cause fluctuating power factor which produces harmonics that interferes with carrier frequency of lower side of
spectrum used and hence generates noise.
The PLC receiver section is similar to the transmitter. The channel estimator and channel compensation blocks are used
to characterise the fluctuating noisy channel of power line and hence to improve SER. The complete Simulink 5.0
system level block diagram is shown in figure 1. The symbol error rates (SERs) with and without RS FEC code can be
observed in scope1 and scope2 respectively. It can be seen that SER is less with RS FEC code.
[attachment=27514][attachment=27514]
ABSTRACT:
This paper describes cost-effective technique for the implementing rural wireless communication network by exploiting
remote RF concept and using existing power line as a physical medium. System level simulation consisting of power
line communication (PLC) transmitter and receiver has been carried out using Simulink 5.0 for noise evaluation. PLC
transmitter and receiver system is proposed using forward error correcting codes (FEC) and orthogonal frequency
division multiplexing (OFDM). It is shown that OFDM can be effectively utilised for base band signal modulation to
achieve both reduced EMI and improved signal-to-noise ratio. MATLAB simulation results indicating the probable
choice of carrier frequencies for PLC are presented.
INTRODUCTION:
There is a great disparity between the rural and urban masses in respect of access to Information and Communication
Technologies (ICTs) and thus leading to greater digital divide between them. Although numerous techniques have been
proposed to minimize this gap by effectively extending ICTs for rural applications to provide locally applicable content
and services but they prove to be expensive due to requirements of wireless infrastructure.
Recently, there has been resurgence of interest in using the existing power line for rural communication as
implementation of orthogonal frequency division multiplexing (OFDM) has become feasible due to technological
advancements. This has opened the gateway for achieving improved SNR (signal to noise ratio) using PLC and utilizing
the easily accessible rural power line as communication medium. Further, the cost of communication can be drastically
reduced by using remote RF in which the existing mobile wireless networks or traditional circuit switched networks of
urban areas can be extended to rural areas [1] [5] [6]. The suggested technique can thus provide cost effective solution
for implementation of wireless communication network without the need of exclusive wireless infrastructure. The PLC
can be used to extend the connection between a wireless radio base station and its antenna, in circuit switched networks
similar concept is implemented via VoIP (voice over IP). This extension can be to provide wireless services to new and
remote areas using radio equipment from an existing location.
This is achieved by transmitting the base band signal through already existing power line to remote rural areas, while
the remote RF is proposed to provide all the necessary backend support for communication network protocol
implementation and resource sharing. The signal processing techniques along with the OFDM offers better solution for
transmission of base band signal on power line. It has been shown that OFDM [9] is relatively immune to EMI, which
has been the prime driving force in studying its SNR performance for PLC [1]. Our simulation results indicate that
OFDM has greater potential for its use in PLC due to having reduced EMI and thus it has been used for generating base
band signal that is launched on power line.
BACKGROUND:
The application for the power line communication would be a system where the wiring would impose the main
expenses and a radio based system would not be feasible or too expensive. These prerequisites for power line
communication system would be met by high voltage or medium voltage power lines because power cables are up to
several tens/hundreds of kilometers and approaching even remote and rural areas. In addition to this PLC requires less
bandwidth.
The voice and data can be integrated using VoIP leading to development of a myriad of multimedia applications. The
international Telecommunications Union (ITU) emphasizes that VoIP can be used in certain areas without the need for
fixed line access [7]. For an example, it can be combined with wireless data technologies, such as Wi-Fi, to serve rural
and remote areas. It is also cheaper for consumers due to the tariff structure. However, when using VoIP, consumers
face a trade off between price and quality. The ITU suggest nevertheless that VoIP can be used to enhance access to
basic telecommunications. Hassan et al. argue that VoIP gives rise to low cost voice calls [8] and several calls can share
the same bandwidth. This is because there is no need for a dedicated communication line per each call as in Plain Old
Telephone Service (POTs).
MATLAB SIMULATION:
The base band signal from legacy networks to provide backend infrastructure support has been generated by Bernoulli
binary generator [3] block (512 kbps). Reed Solomon (RS) double error correcting (15,11) code has been used as FEC
code for base band signal to be sent to remote RF system. Coherent QPSK modulation and training (pseudo noise
sequence generation) blocks are used to provide input to OFDM symbol generation (IFFT add cyclic prefix block).
Training insertion block identifies training pattern in OFDM symbol and place them at predefined position in OFDM
symbol to facilitate training process. The parallel to serial (P/S) conversion block converts parallel data in to serial form
which is sent through power line using PLC coupler. The PLC noise [2] [10] is predominantly due to radio frequency
interference [4] [11] and impulsive noise. The development of PLC noise block is based on the assumption that
impulsive noise is generated because of switching of inductive loads. The switching inductive loads on the power line
cause fluctuating power factor which produces harmonics that interferes with carrier frequency of lower side of
spectrum used and hence generates noise.
The PLC receiver section is similar to the transmitter. The channel estimator and channel compensation blocks are used
to characterise the fluctuating noisy channel of power line and hence to improve SER. The complete Simulink 5.0
system level block diagram is shown in figure 1. The symbol error rates (SERs) with and without RS FEC code can be
observed in scope1 and scope2 respectively. It can be seen that SER is less with RS FEC code.