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Multiple-Input Multiple-Output (MIMO) techniques have recently become an important research field for enhancing the performance of in-home Power Line Communication (PLC) systems by exploiting the additional Protective Earth wire. The development of such systems requires an accurate description of the propagation channel. This paper presents a statistical model for the MIMO PLC channel, based on an extensive set of MIMO channel measurements performed in five houses. In this model, the Phase-Neutral link is described as a multipath channel with frequency variable attenuation, following a formalism first proposed by Zimmermann and extended statistically by Tonello. The full channel matrix is obtained by suitably modifying the path phase. The resulting channel matches our experimental measurements, and reproduces the correlation observed in the measured MIMO channel matrix.

HomePlug AV2 is the solution identified by the HomePlug Alliance to achieve the improved data rate performance required by the new generation of multimedia applications without the need to install extra wires. Developed by industry-leading participants in the HomePlug AV Technical Working Group, the HomePlug AV2 technology provides Gigabit-class connection speeds over the existing AC wires within home. It is designed to meet the market demands for the full set of future in-home networking connectivity. Moreover, HomePlug AV2 guarantees backward interoperability with other HomePlug systems. In this paper, the HomePlug AV2 system architecture is introduced and the technical details of the key features at both the PHY and MAC layers are described. The HomePlug AV2 performance is assessed, through simulations reproducing real home scenarios.

International audienceDespite being a well-established ingredient to many wireless systems, multiple input multiple output (MIMO) signal processing has only recently been considered for broadband power line communications (PLC). Adapting multiple-antenna transmission and reception techniques to a wired medium such as the electrical grid requires solving a number of issues, both regarding the physics of electromagnetic transmission and the optimization of the signal processing strategies. In the last few years, significant steps were made to demonstrate the benefits of MIMO PLC and to develop the necessary hardware. As a result, MIMO PLC has been adopted in several broadband PLC specifications, precisely as part of ITU-T G.hn in Recommendation G.9963, and as part of the industry specification HomePlug AV2, which is backward compatible to IEEE 1901. This article reviews important aspects of MIMO PLC, highlighting its similarities and main differences with classical wireless MIMO. It focuses first on the peculiarities of the electrical grid, with a survey of PLC channel and noise characterization in a MIMO context. It further estimates MIMO PLC channel capacity adhering to the electromagnetic compatibility regulations currently in force. Besides, MIMO signal processing techniques most suited to PLC environments are discussed, allowing for throughput predictions. It is found that eigenbeamforming is the best choice for MIMO PLC: the full spatial diversity gain is achieved for highly attenuated channels and maximum multiplexing gain is achieved for channels with low attenuation by utilizing all spatial streams. It is shown that upgrading from a conventional single input single output (SISO) PLC configuration to a 2 by 2 MIMO configuration the throughput can be more than doubled while coverage is increased. The survey concludes with a review of specific MIMO PLC system implementations in the specifications ITU-T G.9963 and HomePlug AV2

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