There are some exciting new developments in the world of BASE-T Ethernet and wireless.
Last November, the IEEE 802.3 working group held a Call for Interest (CFI) on the need to develop the next generation BASE-T for wireless access points (WAPs). The main issues raised in the CFI were that next generation 802.11ac Wave 2 devices will require multi-gigabit Ethernet data rates, and that there is a gap between the 1 Gb/s and the 10 Gb/s data rates needed to support Wave 2 devices.
The IEEE 802.11ac wireless standard was approved in December 2013. Current Wave 1 devices are using 80 MHz channels and Single-User Multiple-Input and Multiple-Output (MIMO) antennas with a maximum radio speed of 1.3 Gb/s. To support these devices, the network connection speed needs to be at least 75% of the radio speed. Therefore gigabit Ethernet connections over Category 6 or high-end Category 5e cabling are adequate to support Wave 1 devices.
Next generation Wave 2 devices will use 160 MHz channels and more advanced features such as Multiple-User MIMO. It is projected that Ethernet data rates needed to support these devices will approach 2 Gb/s within 12 months, and 4 Gb/s in the next 24-36 months.
Hence the dilemma...
So What is the Solution?
One solution would be to provide multiple gigabit Ethernet connections to each WAP and aggregate the bandwidth. This is not very cost effective.
A better solution would be to provide a 10 gigabit Ethernet connection over Category 6A cabling. Ultimately, this is the way to go.
However, in the meantime, physical layer (PHY) vendors would like to make use of the existing installed base of cabling at an intermediate data rate of 2.5 Gb/s or 5 Gb/s over Category 6 cabling. Or maybe, keeping their fingers crossed, make it work over Category 5e cabling under some conditions.
The chart illustrates the channel bandwidth and encoding requirements that are needed to support gigabit data rates. 10GBASE-T provides a more efficient use of bandwidth as it uses a higher encoding efficiency than 1000BASE-T.
So What is the Drawback?
The drawback is that 10GBASE-T is much more sensitive to external noise such as alien crosstalk (AXT).
What PHY vendors want to do is use 10GBASE-T technology, including the internal noise cancellation algorithms, but scale back the data rate. The net effect of a lower data rate is that less bandwidth is required. For example, Category 6, which is specified to 250 MHz, may be able to support 5 Gb/s, which requires a minimum bandwidth of 200 MHz. This all sounds good; however, detailed cabling requirements still need to be determined.
The Achilles heel when supporting higher data rates for installed base cabling is AXT performance, in particular where Category 5e or Category 6 cables are tightly bundled. These cables are not specifically designed for optimal AXT performance. This is part of the work that needs to be undertaken in the IEEE 802.3 task force.
So in conclusion, the formation of the “Next Generation Enterprise Base-T Access” task force was overwhelmingly approved by the IEEE 802.3 membership. The work is proceeding under the leadership of Intel, Broadcom and Cisco.
It is recognized that the need for the application is imminent and that the technology is already proven. It wouldn’t be surprising to see a standard coming to fruition by mid-2016, and commercial products also available in the same timeframe.
It is clear to see that the wire is what matters for Wave 2 wireless.