MIMO-OFDM narrowband-PLC transmission through distribution transformers: Modeling and achievable data rates

In this paper, the data transmission possibility through distribution transformers is investigated by means of a multiple-input multiple-output (MIMO) narrowband power-line communication (NB-PLC) system utilizing orthogonal frequency-division multiplexing (OFDM). Multi-conductor transmission line theory is used for the accurate modeling of distribution lines, while a simple but efficient measurement-based methodology is adopted for the characterization of the transformer medium-to-low-voltage (MV/LV) side. The equivalent lumped channel frequency response matrix of the 3-phase MV lines cascaded with the distribution transformer is characterized. MIMO-OFDM signal processing techniques are applied to enhance the achievable data rates. The transmit power budget and bit allocation across the OFDM sub-channels are optimized to maximize the data rate through the distribution transformer. The achievable data rates are calculated for different test cases, MV line lengths, and transmission bandwidths, revealing the possibility for an efficient application of two-way MV/LV PLC communications in the framework of smart grid.