It’s been about 7 years since 802.11n Wi-Fi devices operating in both the 2.4 GHz and 5 GHz frequency ranges hit the market, despite the fact that the standard wasn’t ratified until nearly 2 years later.
But now a new generation in wireless technology has arrived!
Operating strictly in the 5 GHz frequency range (5.17 - 5.33 GHz band), IEEE published the 5th Generation 802.11ac™-2013 Wireless LAN Specification early this year with current generation devices providing up to a 3-fold increase in throughput and the potential to eventually provide up to 10-fold at 6.77 Gb/s.
These speeds will rival many existing 100 and 1000 Mb/s wired connections, but there are some considerations.
Like 802.11n, 802.11ac also uses multiple-input-multiple-output (MIMO) technology were multiple signals from one device using different antennas are multiplexed using various spatial streams within the same spectral channel. Compared to 4 spatial streams with 802.11n, 802.11ac increases that number up to 8. For now, most 802.11ac devices in the market are limited to 3.
For most current deployments, 802.11ac devices use an 80 MHz channel width compared to 40 MHz for 802.11n, effectively doubling the data rate. IEEE 802.11ac also has the option of providing 160 MHz channel bandwidth with contiguous and non-contiguous 80+80 MHz channel bonding.
IEEE 802.11ac uses a more efficient modulation scheme MCS 8/9 (256QAM), which provides an additional 33% improvement in data rate for the same channel spectral width compared to 802.11n.
There is a lot more to the IEEE 802.11ac technology, and if you want to know more, there are plenty of various references available. One good example can be found here.
To take advantage of the high data throughput promised by IEEE 802.11ac, gigabit Ethernet connections will be the minimum—with some access points requiring two connections for a 3X3 MIMO with 3 spatial streams to support all existing 2.4 and 5 GHz devices.
One reason that 10GBASE-T is not deployed today for 802.11ac access points may be the requirements for remote powering. PoE switches and midspan injectors are not yet available for 10GBASE-T, but this will change as a new IEEE Study Group is looking at the more efficient option of powering devices, including 10GBASE-T links, using all 4 pairs.
Consequently, it makes sense to install at least one Category 6A cable to each 802.11ac access point. These cables will be required for next generation 802.11 devices.
Looking back at his 42-year career in the cabling industry, Paul Kish was one of the founding fathers of the industry. Retiring from Belden in 2015, Paul was recognized as an expert in cable transmission. He served as a role model, an innovator and a thought leader. Paul was a key contributor to the development of cabling standards with TIA, ISO and IEEE, and also served on the BICSI Technical Information & Methods Committee.