Computer based simulation model realization of OFDM communication over power lines

Although Power Line Communication (PLC) is not a new technology, its use to support data transmission over low voltage (LV) distribution networks is still the focus of ongoing research. This thesis focuses on the channel modelling and performance evaluation of narrowband (NB) PLC system. First, the channel modelling approaches of PLC are studied. Then, the proposed PLC channel modelling method based on the bottom-up approach for LV narrowband PLC in a frequency band between 9 kHz and 490 kHz is presented. This proposed model employs the transmission and scattering matrix methods to calculate the transfer function of a typical LV PLC network which comprises two common cable types (copper cables and aluminium conductor steel reinforced). Unlike the top-down approaches, this model is scalable as the network complexity increases and can better describe the network behaviour as a function of physical parameters.In addition, the noise characteristics and popular noise reduction techniques of PLC are studied. The major impairment to the PLC is the impulsive noise which is mainly generated by the switching transient in the network. Hence, a new technique is proposed to mitigate the impact of impulsive noise on data transmission over power lines. This proposed technique is an optimal Clipping/Blanking nonlinearity technique which is based on the minimum bit error rate (BER) search. Results obtained from the simulation of this technique demonstrate that performance has been enhanced in the NB-PLC system. The performance of the narrowband PLC system is also evaluated in both physical (PHY) and medium access control (MAC) layers. Since Orthogonal Frequency Division Multiplexing (OFDM) is a suitable modulation scheme for hostile environment of the power line, it is used to evaluate the PHY layer performance. As a result of the PHY layer performance analyses, it is found that the BER performance between neighbouring points in the typical LV PLC network is reasonable, but communication beyond one hop have to rely on upper layer protocols. In the MAC layer performance evaluation of the PLC system, the widely known random access MAC protocol that uses the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) will be utilised. The MAC performance evaluation of the PLC system demonstrates a significant packet loss in LV PLC network even with a light traffic condition due to the noisy channel. Furthermore, the goodput declines abruptly once the individual transmission rate is high enough to block the network. In addition, the simulation results show that the channel errors can be reduced by adjusting the MAC parameters to allow the re-transmissions mechanisms to recoup the lost packets.

Broadband low-voltage power line communication (PLC) has many advantages including less investment cost, construction speed, and convenient access. Since the orthogonal frequency division multiplexing (OFDM) technology has strong anti-jamming and anti-frequency selective fading characteristics naturally it becomes a better low voltage power line communication solution. We proposed an OFDM channel estimation method based on compressed sensing (CS) technique according to the channel characteristics of low-voltage power lines. CS algorithm in OFDM system was discussed and an orthogonal matching pursuit (OMP) algorithm was applied to reconstruct the PLC channel information. The simulation results showed that the communication channel estimation method based on CS technique was feasible in PLC system, and the validity of information transmission in OFDM systems can be enhanced.

The power-line communication (PLC) technique involves sending information through an electrical conductor for a commercial or domestic purpose. Lately, electronic means of communication have gained popularity for the transfer of information. Conversely, there is an increased requirement for more transmission media, like the use of power line as a communication channel for remote data delivery. This paper focuses on determining the data rate profile achievable using the single-carrier/multicarrier modulation techniques with Reed- Solomon concatenated convolutional (RS-CC) codes for data transmission through a power line channel. In this investigation, MATLAB/SIMULINK was used to explore a low-voltage power line as a communication channel for high data transmission rate. Data transmission was accomplished by utilizing a parametric model of a power line channel with the different kinds of noise considered in the simulation. In the designed power-line communication (PLC) system, single-carrier modulation offered a maximum of 14.4 Mbps reduction in the data rate when the uncoded 64-quadrature amplitude modulation (QAM) was compared to coded 64-QAM with 1/2 forward error correction (FEC). In the OFDM power-line communication (PLC) system, the decrease in the data rate was maximal at 39 Mbps when the uncoded 16-QAM was contrasted with the 16-QAM having 1/2 FEC. It was evident that the increased code rate of the PLC system using single-carrier and OFDM modulation implied increased data rate profiles

This keynote discusses the behavior of noise in indoor power line communications (PLC) channels. Some ideas to improve system performance based on the knowledge of PLC noise are also introduced. The power-line noise at an outlet is the sum of noise waveforms produced and emitted to the lines from the appliances connected to the power-line network. In the design and the analysis of wireless communication systems, stationary additive white Gaussian noise (AWGN) is often assumed. In PLC systems, however, the statistical behavior of the man-made noise is quite different from that of the stationary AWGN. The fact that the noise in power-lines is not AWGN is often believed to be a cause of low quality of communications. However, Gaussian is the distribution of the largest entropy, and communications under non-Gaussian noise may achieve better performance if the system is designed to adapt the noise statistics. In other words, PLC systems retain large potential for performance improvement if the behavior of the noise is clarified and taken into account in the system design. For narrow-band indoor PLC, we have a mathematically tractable and accurate model based on experimental measurements. In this model, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power-line noise can be described in close form formula with a small set of parameters. In wide-band indoor PLC, we have made measurements with high speed sampling (50MHz) with long observation duration (10.4s).

Power-line Communications (PLC) effectively uses the pervasive power grid as a high data rate communication medium. Despite its advantages, the presence of severe multipath fading and susceptibility to impulsive noise make reliable communication in a PLC system challenging. In PLC systems, orthogonal frequency-division multiplexing (OFDM) is an attractive choice mainly due to its resilience to multipath fading. However, OFDM signals suffers from large peak-to-average power ratio (PAPR) thus resulting in non-linear signal distortions at the transmitter. Therefore, for an OFDM-based PLC system, the combined effect of large PAPR and the presence of impulsive noise results in high bit error rate (BER). This paper proposes the use of precoding at the transmitter to reduce PAPR, and blanking non-linearity at the receiver to mitigate impulsive noise. Precoding is a data-independent and robust PAPR reduction scheme that essentially distributes the power of the individual OFDM symbols over the entire OFDM block. Blanking is an effective impulsive noise mitigation technique that results in better BER performance at the receiver. Simulation results show that, with the combination of precoding and blanking, significant gains in BER performance for an OFDM based PLC system can be obtained with minimal increase of transceiver complexity.

Power line communication (PLC) utilizes power lines for the purpose of electronic data transmission. The performance of a PLC system is significantly affected by the additive and multiplicative power line noises; the additive noises are of two types, namely background noise and impulsive noise. Whereas, the multiplicative PLC noise leads to fading in the received signal strength. In this paper, we evaluate the performance of a PLC system over log-normal fading channel under Nakagami-m distributed additive background noise assuming binary phase shift keying modulation scheme. The analysis involving log-normal fading is very complicated. Hence we use a novel gamma approximation to log-normal distribution for our analysis. We evaluate the probability density function of the decision variable. A closed-form expression of the analytical average bit error rate of the considered system is derived. We also compute the diversity order of the considered PLC system. The validity of the derived analytical expressions is closely verified by the simulation results.

The paper presents a methodology proposal for testing and evaluation of communication systems in Smart Grids, especially for Power Line Communication (PLC) systems. The PLC technology is widely used in power grid as a part of Advanced Metering Infrastructure (AMI) allowing mainly data transfers between a management system at utility and customer-premises smart meters. However, the PLC technology on medium voltage (MV) lines is often used for remote control and monitoring of distribution transformers as well. Since power grid and consequently power lines have different transmission parameters affected by their placement and potentially burdened by interferences, the PLC systems have to be evaluated on site before placed to production. In this paper, authors propose a methodology for long-term benchmarking of the PLC systems using newly developed testing tools. The methodology is subsequently tested on real power grid and a selection of results is presented.

The nature of the Power Line Communication (PLC) equipment is complex because it is considered as an information equipment for Electro-Magnetic Compatibility (EMC) standardization, but it is used to inject High-Frequency (HF) and Very High Frequency (VHF) frequency signals on the existing power network which is not designed to guide these frequencies. This PLC system issue leads to some difficulty to finalize EMC standardization of PLC equipment. This paper shows some EMC issues due to the parasitic radiation of HF and VHF PLC systems. An original method using radiofrequency analysis is used to demonstrate that power lines act as antennas for PLC frequencies, as if the PLC system was a radiofrequency system. So, we can define the PLC system as a "not intended radiofrequency system", i.e. a family product which have to comply not only with EMC standards but also with Radio Equipment Directive (RED) system.

Modern hospitals are beginning to adopt E-HEALTH as efficient complements to the traditional healthcare services. To support the E-HEALTH services, a locatable, radiation-free and high-capacity communication system is urgently needed in hospitals. Power line communication (PLC) system can use the ubiquitous power line network to power the light-emitting diode (LED) lights while serving as the backbone network for the indoor visible light communication (VLC) systems naturally. In this paper, an integrated broadband power line and visible light communication systems with OFDM modulation is proposed for the indoor hospital applications. This gives a brand-new solution to replace the conventional wireless communication systems in hospitals.

The emissions from the power line communication (PLC) system should be investigated for the influence to the electromagnetic environment. The method of moment (MOM) has been studied to estimate the emitted electric field. However, the MOM is difficult to treat the dielectric material of the cable. This paper proposes the method of creating the wire grid model considering the dielectric material of the power line cable. The radius of the wire was determined from the per unit length inductance of the cable. The admittance is inserted between wires to present the effect of the dielectric material, and the value is determined from the admittance calculated by using the FEM based on the two-dimension model. The other admittance was inserted between each wire and ground and the value was also determined from the FEM results. The appliances were presented by T-type network based on the measurement results. The common mode input impedance and radiated magnetic field were measured and compared with the calculated one, and the evaluation indicated that the well agreement was obtained. A simple model of the indoor power line system was constructed and the radiated magnetic field was calculated. The evaluation was indicated that the calculation results almost agreed with the measured one. These results mean that the wire grid model is effective to estimate the radiated electromagnetic field from PLC system.

HF Band Power Line Communication (PLC) is rapidly gaining popularity with new network systems not only in the home, but also in places where the number of users is relatively large. Since the PLC uses wide frequency band for data modulation, some coexistence conditions with other services were provided. We investigated the performance of three types of PLC systems, HD-PLC, HomePlug and UPA, under unfavorable conditions such as connecting the PLC modem to the uninterruptible power supply (UPS) outlet or simultaneously using it with a different PLC system. Although violating the proper instructions, each PLC system could still transfer data to some degrees. It was confirmed that UPS and PLC act as a source of noise for the other PLC systems and the degree of interference varies with the PLC systems used.

In this paper, a method of frame synchronization for narrow-band power line communication (PLC) system employing orthogonal frequency division multiplexing (OFDM) technique is presented. For PLC channel is affected by frequency-selective fading and narrow-band interference problems, frame synchronization can't be achieved by doing correlation between received signal and known data. Instead a special synchronization symbol and proper algorithm are needed so that receiver can start its FFT at the right time. The algorithm is verified in real power line noise and multipath channels, and the performance is evaluated in terms of BER in MATLAB environment.

Power line infrastructure is available almost everywhere. Positioning systems aim to estimate where a device or target is. Consequently, there may be an opportunity to use power lines for positioning purposes. This survey article reports the different efforts, working principles, and possibilities for implementing positioning systems relying on power line infrastructure for power line positioning systems (PLPS). Since Power Line Communication (PLC) systems of different characteristics have been deployed to provide communication services using the existing mains, we also address how PLC systems may be employed to build positioning systems. Although some efforts exist, PLPS are still prospective and thus open to research and development, and we try to indicate the possible directions and potential applications for PLPS.

Power Line Communications have been the subject of an important research work. At the same time, the growing demand for multimedia communications provides a good prospect for PLC as a promising transmission technique for the “last mile” access network. Orthogonal Frequency Division Multiplexing (OFDM) is a spectrally efficient multicarrier modulation technique for high speed data transmission over multipath fading channels. High Peak-to-Average Power Ratio (PAPR) is a major drawback of OFDM. The high PAR of the OFDM signal has to be considered when setting the range of the digital-to-analog converter (DAC) and dimensioning the line-driver. This paper introduced an improved PAPR reduction scheme using constant envelope modulation. Furthermore, by utilizing continuous phase modulation (CPM) in a CE-OFDM system, the PAPR can be effectively reduced to 0 dB. The paper describes a CE-OFDM based modem for Power Line Communications (PLC) over the low voltage distribution network. Relying on a preliminary characterization of a PLC network, a complete description of the modem is given.

Communication is the transfer of information from one point to another over a channel. However, as technology is growing, more information is needed to be passed over large distances for the realization of the world being a global village. There is the need to place a reliable communication system that will transmit effortlessly both data and voice over a channel. Power Line Communication (PLC) also known as Broadband over Power Line (BPL) technology offers high speed and broadband communication services to homes connected to the power lines. This makes use of the electrical lines for transmission of data up to the last mile and there is no need of separating copper cables, short haul satellite systems, optical fibre cable and Wi-Fi. This work presented an overview of a voice and data communication over PLC in terms of the various types, equipment use, method of communication, application, regulatory activities on PLC and the challenges facing the implementation of power line for transmitting voice and data. Therefore, PLC is a viable alternative to all other methods of transmission as it is readily available and can be easily implemented in rural areas where other communication systems are not implemented for the transmission of voice and data communication. Keywords: Communication, Power Line Communication, Broadband over Power Line, Voice and Data Communication, Broadband over Power Line, Transmission, Electrical Line. DOI : 10.7176/MTM/9-8-03 Publication date : August 31st 2019