Previously, we learned that G.hn is an ITU-T protocol designed for communications over any wired medium such as Powerlines, Coax, Twisted-pair etc. Let’s now explore how this is done at a high level. On the left, is a diagram for Ethernet communications and on the right an equivalent for G.hn communications. These diagrams illustrate at a high level how Ethernet frames are wrapped into G.hn frames and transmitted over any wired medium using OFDM modulation.  Instead of Ethernet’s Multi-level transmit encoding, G.hn uses orthogonal frequency division multiplexing OFDM modulation which utilize multiple frequency carriers for data encoding to overcome harsh wire conditions; achieving high signal to noise ratio and very long distance communications. The G.hn frames further protect the data with LDPC Forward Error Correction for resilience over noisy wires like Power Lines. The G.hn Media Access Controller predominately utilizes Time Division Multiple Access (TDMA) with secondary provision for Collision Avoidance Carrier Sense Media Access (CSMA/CA). This means G.hn is non-contention based communications protocol that can also be compatible with contention based arbitration of a wire medium by large number of communication nodes.  G.hn communications can be secure with the use of AES 128-bit based encryption and 802.1x authentication protocol. Lastly, unlike Ethernet where active switches are required to connect multiple nodes, G.hn does not require active switching and all that is needed is to connect the wires together. Not only can G.hn communicate over any wires but it can handle harsh conditions of power lines in a home, building and even the grid, making it suitable for PLC for home, office or SmartGrid networking.