DIGITAL SIGNAL PROCESSING

Power Line Communication

Power Line Communication

Introduction

Power line communication (PLC) is a technique transmitting voice or data at a rapid speed through a power line in a house, an office, a building, and a factory, etc. Power-line communication systems have become increasingly viewed employed as an attractive alternative to conventional hard-wired communication systems, which require dedicated communication wiring, and wireless systems, which involve complex and costly transmitter and receiver circuits. In power line communication, the existing alternating current (AC) power wires serve as a transmission medium by which information is relayed from a transmitter or control station to one or more receivers or loads connected downstream from an AC source. There is a significant advantage to the use of alternating current (AC) power lines for purpose of communication between electronic devices using a power line communication system. Since no new wires are required to implement the function of communication, power-line communication systems greatly reduce the complexity and effort of installation, particularly in building retrofit applications in which it is highly desirable to be able to install an energy control system with little or no alteration of the existing electrical wiring. The powerline communication technology utilizes a power line as a signal transmission channel. This technology makes it possible to perform communication between a plurality of communication devices by connecting each of those devices to a receptacle installed in each room in a house. Use of existing power lines as a communication medium eliminates installation costs for adding dedicated communication wiring to existing structures. Such a power line communication system can be used for monitoring and controlling basic function including energy management, security, and safety control in applications including homes, factories, offices, automobiles and aircraft. Electric utility companies utilize power line communication systems to provide a means for a central station to communicate command signals to remote receivers which are located at the sites of electric energy consumers (Dostert, 1997).

The infrastructure for providing broadband Internet access is presently insufficient to meet demand. With some modification, the infrastructure of the existing power distribution systems can be used to provide data communication in addition to power delivery, thereby forming a power line communication (PLC) system. Development of a power line communication system would therefore provide more users with high-speed telecommunications access. The PLC communication may be applied to various fields such as super high-speed Internet communication, Internet phone, home networking system, home automation and remote metering system just by connecting a plug of a computer to a power source without using LAN or a telephone. The usual power distribution system in a building is a system of wires, electric outlet receptacles, fuses and/or circuit breakers, switches and controls and permanently wired fixtures and appliances, installed for the purpose of distributing low frequency AC power in the building. In the PLC system, a radio frequency communication signal of a few hundreds Hz to a few tens MHz is transmitted together with an alternating power to a power line supplying the alternating power having frequencies of ...