G.hn, a technology for existing-wire home networking that is intended to complement Wi-Fi, has been approved for use in Smart Grid applications by the National Institute of Standards and Technologies (NIST). This follows on the heels of last summer’s Electric Power Research Institute (EPRI) report to NIST that defined the full scope of communications among electric utilities, aggregators, regulators, and home/industrial consumers that will constitute the Smart Grid. G.hn would be one contender for communications between the electric meter and home appliances and electric-vehicle charging stations that will be capable of using electricity rates broadcast to the home in order to schedule operation. Ultimately, the Smart Grid will use a wide spectrum of communications technologies to link all its stakeholders. The goals of the Smart Grid are to achieve efficiency through load leveling and to make the power grid more robust in the face of natural disasters and sabotage. (see “Smart-Grid Report Maps Opportunities For U.S. Engineers,” ED Online 21465)
G.hn targets gigabit/second data rates over in-home electrical wiring, telephone/CAT5 twisted pair, and coax. The standard specifies a single physical layer based on FFT orthogonal frequency domain multiplexing (OFDM) and low-density parity-check (LDPC) forward error correction. It is intended to notch specific frequency bands to avoid interference with amateur radio and other licensed radio services. Other mechanisms are intended to avoid interference with legacy home networking and DSL technologies. At the medium access control layer, G.hn relies on TDMA and a "domain master" that schedules Transmission Opportunities (TXOPs) that can be used by devices in the "domain."
G.hn is supported by HomeGrid Forum, a global non-profit trade group.