How a standard is born: IEEE P1901.2 for narrowband OFDM PLC
History: The Formative Stages of a Standard
Formation of the P1901.2 work group started in early 2009 with PLC discussions among several companies attending automotive standards meetings. The discussions centered on how to standardize on a sub-500kHz PLC solution that would meet the upcoming automotive specifications SAE J2931/3 and ISO/IEC 15118-3. At that time, there was limited standardization effort for PLC solutions above the CENELEC® band in the low-frequency (FCC and lower) range. Further discussions took place mid-November 2009 in Denver, Colorado, at a NIST-sponsored PAP15 meeting, where NIST (National Institute of Standards and Technology) outlined the need for powerline standards with global coexistence. After additional meetings and with direction from the Board of Governors of the IEEE® Communication Society (Comsoc), it was determined that the best path forward would be to approach IEEE for sponsorship of a new standard effort for a PLC solution below 500kHz.
A table similar to Figure 1 was presented to the IEEE Comsoc in late 2009. At this meeting the IEEE Comsoc agreed to sponsor a new standard development around LF NB PLC.
Consequently, the next step was to generate a working-group PAR (project authorization request). Over the next month, a PAR2 was developed, submitted, and approved with the following scope:
Scope: This standard specifies communications for low-frequency (less than 500kHz) narrowband powerline devices via alternating current and direct current electric powerlines. This standard supports indoor and outdoor communications over a low-voltage line (line between transformer and meter, less than 1000V), through a transformer low-voltage to medium-voltage (1000V up to 72kV), and through transformer medium-voltage to low-voltage powerlines in both urban and in long-distance (multi-kilometer) rural communications. The standard uses transmission frequencies less than 500kHz. Data rates will be scalable to 500kbps depending on the application requirements. This standard addresses grid-to-utility meter, electric vehicle-to-charging station, and within home area networking communications scenarios. Lighting and solar-panel powerline communications are also potential uses of this communications standard. This standard focuses on the balanced and efficient use of the powerline communications channel by all classes of low-frequency narrowband (LF NB) devices, defining detailed mechanisms for coexistence between different LF NB standards developing organizations (SDO) technologies, assuring that desired bandwidth may be delivered. It also ensures coexistence with broadband powerline (BPL) devices by minimizing out-of-band emissions in frequencies greater than 500kHz. The standard addresses the necessary security requirements that assure communication privacy and allow use for security sensitive services. This standard defines the physical layer and the medium access sublayer of the data link layer, as defined by the International Organization for Standardization (ISO) Open Systems Interconnection (OSI) Basic Reference Model.3
With additional explanatory notes:
The effort will consider existing narrowband powerline communications technologies, which operate below 500kHz as a starting point, and will review coexistence, EMC, and performance data in the application scenarios covered. The standards initiative will harmonize with technologies operating in the same field (LF NB), data rate (scalable to 500kbps) and frequency band (frequencies 500kHz and lower), along with unifying ongoing global smart grid PLC projects). IP addressing will also be a priority with consideration for IPv6 or IPv6/IPv4 dual stack to support legacy device operation. These will form the basis for detailed scope of task group that will work within P1901.2 to develop the components of the final standard.4
As a result of the approved PAR, the IEEE P1901.2 work group formed several subgroups to address solutions for various key areas. These areas included harmonization technologies operating in a low-frequency band; robustness for through-transformer communication; defining limits and testing for EMC; defining a complete coexistence mechanism with existing SDO technologies; and prioritizing IP addressing.