Influences of Periodically Switching Channels Synchronized with Power Frequency on PLC Equipment

The regulation on power line communication (PLC) has been eased in Japan, and the frequency band between 2 and 30 MHz can be used for in-home PLC. Several different types of commercial PLC equipment are available in the market. Almost all of them include PLC adapters that interconvert Ethernet signals and power line signals. An in-home network can easily be constructed by using these PLC adapters because there are many power outlets in every room. However, there are various factors that tend to destabilize the communication among PLC adapters. These factors involve time-varying channel response and noise characteristics, which are both synchronized with the power frequency. In particular, it has been observed that the noise in a power line varies more significantly than the channel response. Therefore, many PLC adapters contain certain features to mitigate the time-varying noise in a power line. We show a number of examples of more significant variations in the channel response synchronized with the power frequency due to the switching regulators used. This paper deals with such a time-varying channel response synchronized with the power frequency. We show that the performance of the PLC adapters suffers due the time-varying channel response and analyze its influences on the PLC adapters.