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The IEEE Std 1901-2010 is a standard for high speed (up to 500 Mbit/s at the physical layer) communication devices via electric power lines, often called broadband over power lines (BPL).  The standard uses transmission frequencies below 100 MHz. This standard is usable by all classes of BPL devices, including BPL devices used for the connection (<1500m to the premises) to Internet access services as well as BPL devices used within buildings for local area networks, smart energy applications, transportation platforms (vehicle), and other data distribution applications (<100m between devices).
The IEEE Std 1901-2010 standard replaced a dozen previous powerline specifications. It includes a mandatory coexistence Inter-System Protocol (ISP). The IEEE 1901 ISP prevents interference when the different BPL implementations are operated within close proximity of one another.
The 1901 standard is mandatory to initiate SAE J1772 electric vehicle charging and the sole powerline protocol for IEEE 1905.1 heterogeneous networking. It was highly recommended in the IEEE P1909.1 smart grid standards because those are primarily for control of AC devices, which by definition always have AC power connections - thus no additional connections are required.
The IEEE P1901 Working Group started in June 2005. More than 90 organizations contributed to the standard. Half of the organizations were from US, a quarter from Japan and the last quarter from Europe.
IEEE 1901 completed a formal standard IEEE Std 1901-2010 published in December 2010. The working group which maintains and extends the standards is sponsored by the IEEE Power Line Communication Standard Committee (PLCSC).
The IEEE 1901 ISP coexistence protocol was extended to support the International Telecommunication Union's family of home networking standards known as G.hn, and adopted by the ITU-T as Recommendation ITU-T G.9972.
The Smart Grid Interoperability Panel (SGIP) initiated by the U.S. National Institute of Standards and Technology (NIST) mandates the implementation of the IEEE 1901 ISP coexistence mechanism (or ITU-T G.9972) in all technologies operating over power lines. NISTIR 7862: Guideline for the Implementation of Coexistence for Broadband Power Line Communication Standards  The IEEE 1901 standard is included in the SGIP Catalog of Standards 
The SAE J1772 and IEC 62196 standards for electric vehicle charging include IEEE 1901 as the standard for power line communication between the vehicle, off-board charging station, and the smart grid, without requiring an additional pin; SAE International and the IEEE Standards Association are sharing their draft standards related to the smart grid and vehicle electrification.
The 1901 standards include two different physical layers, one based on FFT orthogonal frequency-division multiplexing (OFDM) modulation and another based on wavelet OFDM modulation. Each PHY is optional, and implementers of the specification may, but are not required, to include both. The FFT PHY is derived from HomePlug AV technology and is deployed in HomePlug-based products. The Wavelet PHY is derived from HD-PLC technology and is deployed in HD-PLC-based products.
The fast Fourier transform (FFT) PHY includes a forward error correction (FEC) scheme based on convolutional turbo code (CTC). The second option "Wavelet PHY" includes a mandatory FEC based on concatenated Reed-Solomon (RS) and Convolutional code, and an option to use Low-Density Parity-Check (LDPC) code.
On top of these two physical layers, two different Media Access Control (MAC) layers were defined; one for In-home networking and the other for Internet access. Two MACs were needed because each application has different requirements.
To manage coexistence between PHYs and MACs the Inter-System Protocol (ISP) was developed. ISP enables various BPL devices and systems to share communication resources (frequency/time) when installed in a network with common electrical wiring. ISP allows 1901-compliant devices and ITU-T G.hn- compliant devices to co-exist. The protocol provides configurable frequency division for Access and time division for in-home with a granularity compatible with the Quality of Service (QoS) requirements of the most demanding audio and video applications.
Another trade group called the HomeGrid Forum was formed in 2008 to promote the ITU-T home networking standards known as G.hn. Recommendation ITU-T G.9972  approved in June 2010, specifies a coexistence mechanism for home networking transceivers capable of operating over powerline wiring. This recommendation is based on IEEE 1901 ISP.
IEEE 1675 was approved in 2008. It provided testing and verification standards for the hardware commonly used for broadband over power line (BPL) installations (primarily couplers and enclosures) and standard installation methods to ensure compliance with applicable codes and standards.
"IEEE 1775".: Power Line Communication EMC Working Group.
Other IEEE standards sponsored by the Power line Communication Standards Committee:
The IEEE 1901.2 Standard for Low Frequency (less than 500 kHz) Narrow Band Power Line Communications for Smart Grid Applications was authorized in 2010 and approved its standard by October 2012.
"IEEE P1909.1".: Recommended Practice for Smart Grid Communication Equipment -Test methods and installation requirements
The IEEE 1901 standards are promoted by trade groups such as the HomePlug Powerline Alliance and the HD-PLC Alliance. Panasonic is a member of the HD-PLC Alliance, and licenses its patents and technologies that support IEEE 1901. K-Micro (also a member) announced a product in 2011. The Qualcomm Hy-Fi networking marketing program combines IEEE 1901 (on AC outlets in every room) with IEEE 802.11ad branded as Wi-Fi (which does not penetrate walls).
Because IEEE 1905 includes and requires IEEE 1901 compliance, it and the nVoy certification regime indicate 1901 compliance also.
Generally consumers rely on the nVoy mark to show that the device supports IEEE 1901 gigabit networks.