HD-PLC Alliance

The IEEE Standard for Coexistence between Different PLC Systems

The approval of standards for PLC by the IEEE P1901 (Institute of Electrical and Electronic Engineers) as a baseline technology has accelerated the widespread adoption of HD-PLC. The main reason that these standards have caused such an impact on the industry is the fact that they outline rules bringing together the various types of PLC. This ensures that HD-PLC can coexist with other IEEE systems on the same power line network.

HD-PLC Alliance's booth

HD-PLC Alliance's booth at International CES The approval of the PLC standard as a baseline technology by IEEE P1901 was mentioned on the main stage and at reception.

There are several standards for PLC, including HD-PLC, but in previous systems, data could not be exchanged when devices with different standards were connected in a network. This is because the signals sent by PLC devices with different standards were deemed as noise. Furthermore, since different PLC devices attempted to communicate with each other on a limited bandwidth, this could lead to disorderly communication and interference between devices. To alleviate this problem, IEEE established the P1901 Working Group in June 2005 to develop a standard for PLC.
Also, Panasonic System Networks Co., Ltd. (formerly, Panasonic Communications Co., Ltd.), a member of the HD-PLC Alliance, established CEPCA (Consumer Electrics Powerline Communication Alliance), an organization that promotes the standardization of PLC in cooperation with manufacturers who use other PLC standards in June 2006. They drew up a draft proposal for standardization prior to IEEE, and proposed it to IEEE P1901.

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Checking for Other Devices via Standard Identifying Signals

The IEEE P1901 standard specifies that a device that transmits PLC data must include a signal to identify which PLC standard was used to send the data. Devices such as the PLC adaptor send identifying signals periodically, which is like saying, “I (the device) was manufactured based on this standard”. A PLC device connected to the network checks data, and when it detects data of a different standard to its own, it realizes that another standard exists on the network. Then, the two devices automatically switch to a coexistence mode to avoid interfering with each other. This allows users to connect to a network without having to worry about the different standards, as long as they are using devices that are IEEE P1901-compliant.
This system is effective not only for in-home networks, but also in the future when it will be more common to use PLC via power lines connected to telephone poles instead of using access lines outside the home, such as optical fiber or ADSL. Since there are differences between indoor and outdoor networks, it is necessary to connect the two without any problems. This recently approved standard which can connect different types of networks, does not only apply to different PLC standards, but also, theoretically, for connecting indoor and outdoor networks. In addition, application in transport systems should become possible in the same way as indoor systems.

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