After its release as an IEEE standard in 2003, Power over Ethernet (PoE) has continued its upward spiral in performance, demonstrating an ability to transfer Ethernet data at faster speeds and dc power at higher levels—all in a single eight-wire bundle. And every enhancement to the standard adds to its popularity, so much so that most analysts project global revenue from PoE power-sourcing equipment (PSE) and powered devices (PDs) will reach at least $3 billion in 2025 from less than $1 billion today. To meet the challenge of the latest PoE standard, PSE equipment and the PDs themselves will need controllers capable of handling it.
When PoE emerged in 2003 as the IEEE 802.3af standard, only 13 W at 350 mA could be transferred over a distance of 100 m, which was sufficient for powering some VoIP systems, CCTV cameras, and RFID along with other types access control. However, devices such as videoconferencing, Wi-Fi routers, pan-tilt-zoom or heated cameras, and door interlock systems draw more current, so they were beyond the means of 802.3af to power them.
In 2009, the IEEE 802.3at enhancement was ratified, which increased power to 25.5 W at 600 mA, solving the problem for some of these systems. However, others were still tethered to the 120-V ac mains. The next version, 802.3bt, brings maximum power to about 90 W, which accommodates many more types of devices, including even cellular small-cell base stations. It should be ratified before the end of the year.
In addition, since PoE was first standardized, almost all electronic systems have become far more efficient, further adding to the list of potential PoE candidates. Thus, thanks to the increased power delivery of PoE combined with more efficient devices in general, 802.3bt should significantly boost PoE’s popularity in the future.
Facilitating the Smart Building
One of the key target markets for 802.3bt is the so-called “smart” building, as it incorporates a significant portion of the devices that can be PoE-powered. It also offers the added benefit of allowing every one of them to have its own IP address. The latter will be enormously important in these buildings, which will incorporate hundreds or even thousands of sensors and all must be monitored and controlled from a single management system, either locally or virtually anywhere via the internet.