Inhome Power Line Communications using Multiple Input Multiple Output Principles

Inhome power line communications (PLC) allows new and highly convenient networking functions without any additional wires to mains-powered devices. Today’s PLC systems feed and receive the signals differentially between the phase and neutral wire creating single input single output (SISO) transmission. 3-wire installations, including the protective earth wire, allow feeding and receiving on multiple ports, permitting multiple input multiple output (MIMO) transmission. Up to two transmit and four receive ports may be used. This thesis investigates the application of MIMO to inhome PLC. The characteristics of the MIMO-PLC channel, including the channel capacity, are analyzed based on MIMO measurements in several buildings. It will be shown that the MIMO channel capacity is doubled on average compared to SISO. In particular, the bitrate of highly attenuated channels is increased mostly leading to a significant improvement of the PLC’s coverage. A comparison of different MIMO schemes di- rects to the development of a dedicated MIMO-PLC system. The proposed system comprises precoded spatial multiplexing (Beamforming) in conjunction with adaptive OFDM (orthogonal frequency division multiplex) modulation. An implementation of a real-time system proves the expected gain of MIMO for real MIMO-PLC channels.