5G-Exclusive
Technology for the 5G Generation & Beyond
Galit Mendelson
Senior Manager of PoE Marketing & Business Development | Microchip Technology, (www.microchip.com)
How to deliver up to 90 watts of Power over Ethernet wiring in an existing switch infrastructure The Advancement of 5G and PoE
As next generation 5G technology comes to the mainstream, it opens new business opportunities that rely on a variety of IoT and Big Data applications driven by higher data rates and power. There is a greater need to connect powered devices (PDs) such as 802.11ac and 802.11ax access points, 5G small cells, IP surveillance cameras, LED luminaires, and other IoT appliances to Ethernet networks. Power-over-Ethernet (PoE) technology works well to power these devices in 5G deployments, facilitated by the latest IEEE® 802.3bt standard that pushes the power limits of Power Sourcing Equipment (PSE) and Powered Devices (PDs) to 90W and 71.3W respectively. Ensuring that the PDs that support this latest generation of PoE technology can still work with existing pre-IEEE® 802.3bt 2-pair and 4-pair PDs that support legacy PoE standards is a challenge. This issue has now been resolved since pre-standard and new IEEE® 802.3bt-2018-compliant PDs can share the same Ethernet infrastructure and don’t require changes to existing switches or cabling.
The Road to IEEE 802.3bt
The first PoE standard was ratified in 2003. Since then, PoE adoption has picked up as it is finding its way into powering new applications. PoE offers several advantages such as ease of installation and lower CAPEX and OPEX costs. It has also emerged as a unified and safe power standard that can be used worldwide. In the early years, the primary drawback with PoE was that the amount of power available wasn’t sufficient for devices such as IP video phones, 802.11n, and pan-tilt-zoom (PTZ) IP cameras, although it worked well for most IP phones and 802.11a/b/g access points. To address this, the Institute of Electrical and Electronic Engineers (IEEE) specified 30W at the PoE source when it released IEEE 802.3at-in 2009.
With devices such as PTZ security cameras, kiosks, POS terminals, thin clients, 802.11ac and 802.11ax access points, small cells, and connected LED lighting connected to the Ethernet network, there is demand for even higher power. Addressing this requirement, the new IEEE 802.3bt standard utilizes all four pairs of the structured wiring, thereby increasing the maximum PoE power. IEEE 802.3bt extends the power classification information exchanged during initial negotiation to allow meaningful power management capability, enabling support of multiple PoE classes, while also being backwardcompatible. In turn, this helps achieve higher power and more efficient PoE delivery systems. The IEEE 802.3bt standard was ratified in September 2018, five years after the Call for Interest (CFI) activity started. The new standard facilitates the expansion of PoE use cases since it pushes the power limit of PSEs and PDs to 90W and 71.3W respectively. This makes it a major catalyst to PoE market growth. In the past too, efforts were taken to increase power delivery to PDs. First, the IEEE 802.3af-2003 PoE standard was launched and could provide up to 15.4W of output power to each device over two pairs of Category 5e (Cat5e) cables. Then, the IEEE 802.3at-2009 standard, also known as PoE+, which is an extension of the first standard, could support 30W output power and 25.5W load power through the “Type 2” PSE/PD. We then saw the emergence of the HDBaseT Alliance, which helped standardize the HDBaseT protocol. This standard allowed the HDMI links to be extended up to 100m over Cat5e or better cables. In 2011, the Power over HDBaseT (PoH) standard, which was created by the HDBaseT Alliance, could extend the maximum power deliverable to 95W over four pairs. The following table summarizes the pre-IEEE 802.3bt standards:
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