IEEE P1901

IEEE P1901 ("IEEE P1901 Draft Standard for Broadband over Power Line Networks: Medium Access Control and Physical Layer Specifications") is an IEEE draft standard for broadband over power line networks defining medium access control and physical layer specifications. Although baseline approval was originally expected for 2008, the two negative confirmation votes that took place in July 2008 (Miami meeting) and Oct 2008 (Madrid meeting) could make this milestone difficult to achieve. After 2 negative confirmation votes, the P1901 process has been reset.

cope

The project will develop a standard for high speed (>100 Mbit/s at the physical layer) communication devices via alternating current electric power lines: so-called "Broadband over Power Line" (BPL) devices. The standard will use transmission frequencies below 100 MHz; it will be usable by all classes of BPL devices, including those used for the first-mile/last-mile connection (<1500 m to the premise), to broadband services, as well as BPL devices used in buildings for LANs and other data distribution (<100 m between devices). This standard will focus on the balanced and efficient use of the power line communications channel by all classes of BPL devices, defining detailed mechanisms for coexistence and interoperability between different BPL devices, and ensuring that desired bandwidth and quality of service may be delivered. P1901 will address the necessary security questions to ensure the privacy of communications between users and allow the use of BPL for security sensitive services. This standard is limited to the physical layer and the medium access sub-layer of the data link layer, as defined by the International Organization for Standardization (ISO) Open Systems Interconnection (OSI) Basic Reference Model. The effort will begin with an architecture investigation, and this will form the basis for detailed scope of task groups that will work within P1901 to develop the components of the final standard.

Purpose

New modulation techniques offer the possibility to use the power lines for high speed communications. This new high speed media is open, and locally shared by several BPL devices. Without an independent, openly defined standard, BPL devices serving different applications will conflict with one another and provide unacceptable service to all parties. The standard will provide a minimum implementation subset which allows the fair coexistence of the BPL devices. The full implementation will provide the interoperability among the BPL devices, as well as interoperability with other networking protocols, such as bridging for seamless interconnection via 802.1. It is also the intent of this effort to quickly progress towards a robust standard so powerline applications may begin to impact the marketplace. The standard will also comply with EMC limits set by national regulators, so as to ensure successful coexistence with wireless and telecommunications systems.

"Dual PHY" Controversy

The proposal selected by the P1901 Working Group in October 2007 has been controversial, because it does not provide a unified PHY layer. Instead, the proposal included two different PHY layers, one based on OFDM modulation and another based on Wavelet modulation. Each PHY is optional, and implementers of the specification would not be forced to include both. This would mean that devices that use the OFDM PHY would not interoperate with devices based on Wavelet PHY. Some members of P1901 maintain that this lack of interoperability defeats the purpose of having a standard [http://www.edn.com/blog/630000263/post/220026822.html How To Kill The Home Networking Industry] , provides an overview of the controversy around the dual-PHY proposal at P1901] .

The IEEE has a long history of controversial PHYs, with 802.11 having four PHY which all lack of interoperability, leading to one of the most successful standards around.

A vote on July 2008 to confirm the "dual PHY" proposal failed to get the required number of backers. The confirmation vote failed [http://www.eetimes.com/news/design/showArticle.jhtml?articleID=208808680 Powerline standard stuck in stalemate] , HomePlug/Panasonic proposal fails in latest vote] . A second vote in October 2008 also failed to get the required number of positive votes (75%) [http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=210605077 Standard to unify powerline shot down in Madrid] , Standard to unify powerline shot down in Madrid] . The IEEE P1901 process specifies that if the proposal suffers two negative confirmation votes, the process has to be reset, and the three last surviving proposals have to be reconsidered by the group. During the October 2008 P1901, a reset indeed did occur and a new eliminate vote was made which reconfirmed the HomePlug/Panasonic proposal as the candidate P1901 baseline. See http://grouper.ieee.org/groups/1901/.

ee also

*Power line communication

External links

* [http://grouper.ieee.org/groups/1901/ IEEE P1901 Official site]
* [http://standards.ieee.org/board/nes/projects/1901.pdf IEEE P1901 PAR] describes the official scope of the work group

References

----This article incorporates some information taken from [http://grouper.ieee.org/groups/1901/ IEEE P1901 Official site] with permission.