Optimized MIMO-OFDM design for narrowband-PLC applications in medium-voltage smart distribution grids

In this paper, a multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system is proposed for narrowband power-line communication (NB-PLC) applications in medium-voltage (MV) networks. Multi-conductor transmission line theory is used for accurate MV NB-PLC channel characterization and evaluation of the spatial correlation between the phase conductors. By optimizing the indices of the active OFDM sub-channels, the bit allocation across them, and the transmit power allocation across the spatial beams, the proposed MIMO-OFDM design can achieve significant data rate gains over single-input single-output OFDM transmission. The achievable MIMO-OFDM data rates are evaluated for an MV overhead network with different lengths, coupler impedances and branches, showing that the proposed MIMO-OFDM design is an efficient implementation of NB-PLC technology in MV smart distribution grids.