OFDM signal transmission characteristics through a switchboard for a power line communication

In this paper, we paid to attention for the switchboard actually used at house, and evaluated the transmission loss characteristic of the power line transmission model with the switchboard, and its influence to the transmission speed of OFDM signal. First, in case of power line transmission model without the circuit line, it was confirmed that the transmission loss characteristics inside a circuit breaker and through a main breaker are almost the same characteristics, but the transmission loss in the in-phase is smaller by about 10dB than that in the out-of-phase. PHY rate of in-phase transmission is full PHY rate of about 185Mbps, but PHY rate of out-of-phase transmission decreases to 150Mbps. Next, in case of power line transmission model with the branch line, the transmission loss characteristic in the in-phase and the out-of-phase transmissions had sharp attenuation of about 20dB at the frequency of around 4MHz, because of the signal resonance in the branch line (10m length). However, this sharp attenuation did not affect to PHY rate in the in-phase transmission, if anything, in the out-of-phase transmission, PHY rate was improved by the branch line. Finally, PHY rate of PLC modem was calculated by MATLAB/ Simulink, and compared with measurement value. It was understood that the calculation value almost agreed with the measurement one in the in-phase transmission.