Research About The Low-voltage PowerLine Network Communication Technology

PowerLine Communication technology is catching our attention greatly now, which uses the power line as a communication media to create a high speed data channel and supply services such as high speed Internet access, and create great economic and social profit. Using the technology, we can get a broad band access within rang of a distribution transformer as well as a home LAN through outlet of every house. It's a complementarity and extent of other broad band access method. As the high speed power line communication uses the intrinsic powerline and the number of power users of 220V is much larger than that of CATV and ADSL, this technology has a large number of latent users.This paper presents the characteristics of data communication over low-voltage power line, the principle and implementing method of OFDM and the PLC-USB terminal. Orthogonal Frequency Division Multiplexing (OFDM) with signal processing techniques for high data reliability in noisy media conditions. Power line communication (PLC) technology, however, the technology has not been widely adopted in network businesses due to low speed, low functionality, high cost and other barriers. OFDM is one of the technologies for resolving this problem .The principle of OFDM is simple, that is instead of transmitting at a high transmission rate on a single carriers, transmitting at a low transmission rate on multiple carriers. The coupling module of PLC-USB terminal provides a low impedance path for the high frequency communication signal .The functions of the AFE module are including filters, AGC and TX/RX switch. The INT51X1 implements patented PowerPacket OFDM technology, which forms the basis for the HomePlug 1.0.1 Specification. Specifically tailored to reliably deliver up to 14 Mbps over the difficult power line communication environment. The IC combats deep attenuation notches, noises sources, and multi-path fading by allocating usable frequencies according to the signal to noise ratio (SNR). The MAC implements a CSMA/CA scheme with automatic repeat request (ARQ) for reliable delivery of Ethernet packets via packet encapsulation. INT51X1 integrated 10-bit ADC, 10-bit DAC and AGC Control circuitry.PLC-USB terminal is available for use in a wide range of settings, including residential (in-home), commercial (offices, apartments , hotels, warehouses), transportation and defense applications .At present, this PLC-USB terminal has been used by many people and it is already of enough competition capability to provide fast, reliable and inexpensive communication services for residential users by power distribution lines now available.