Cisco Cisco Aironet 1850e Access Points Libro blanco
IEEE 802.11ac Wave 2 AP’s: Cisco, Aruba, Ruckus
5
DR151120D
Copyright © Miercom 2015
5 February 2016
Notes:
(1) Spatial streams: the number of sending and receiving antennas supported, more spatial
streams helps boost data rates and distance.
(2) MU-MIMO: Multi-User, Multiple-Input, Multiple-Output, increases client density, the
number of simultaneously supported clients requires beamforming support.
(3) The above theoretical capacities are based on PHY rate and these configurations:
802.11n: three spatial streams x 150 Mbps per spatial stream; 40-MHz channel, 400 ns
guard interval, 64-QAM modulation at 5/6 rate.
guard interval, 64-QAM modulation at 5/6 rate.
Wave 1: three spatial streams x 433.3 Mbps per spatial stream; 80-MHz channel, 400
ns guard interval, 256-QAM modulation at 5/6 rate.
ns guard interval, 256-QAM modulation at 5/6 rate.
Wave 2: three spatial streams x 866.7 Mbps per spatial stream; 160-MHz channel, 400
ns guard interval, 256-QAM modulation at 5/6 rate.
ns guard interval, 256-QAM modulation at 5/6 rate.
The table shows the characteristics of the specifications that are built into products, and not
necessarily the maximum allowed by the particular standard. For example, while the IEEE
802.11ac standard allows up to eight spatial streams to be supported by an 802.11ac-compliant
device, Wave 2 products support up to three, and optionally four, downlink spatial streams.
The same is true regarding data rates. The standards specify the data rates relative to the
signaling support of compliant products at the Layer-1 physical, or PHY, level. But this does not
equate to the data rate that users would experience. Overhead above the physical level, such as
MAC and Ethernet at Layer-2, IP at Layer 3, and UDP – and especially TCP – at Layer-4, reduce the
effective, actually achievable data rates. In addition, predicted max data rates usually assume a
perfect WiFi environment, devoid of interference and other electromagnetic anomalies, which is
seldom the case.
To summarize, there are four notable advantages of Wave 2 – versus products based on Wave 1
and earlier WiFi standards:
necessarily the maximum allowed by the particular standard. For example, while the IEEE
802.11ac standard allows up to eight spatial streams to be supported by an 802.11ac-compliant
device, Wave 2 products support up to three, and optionally four, downlink spatial streams.
The same is true regarding data rates. The standards specify the data rates relative to the
signaling support of compliant products at the Layer-1 physical, or PHY, level. But this does not
equate to the data rate that users would experience. Overhead above the physical level, such as
MAC and Ethernet at Layer-2, IP at Layer 3, and UDP – and especially TCP – at Layer-4, reduce the
effective, actually achievable data rates. In addition, predicted max data rates usually assume a
perfect WiFi environment, devoid of interference and other electromagnetic anomalies, which is
seldom the case.
To summarize, there are four notable advantages of Wave 2 – versus products based on Wave 1
and earlier WiFi standards:
(1) Higher data rates: Up to 2.6 Gbps in the 5 GHz band
(2) Multi-User MIMO (Multiple-Input, Multiple Output) support
(3) 160-MHz channel width support; key to increased data rate, essentially double Wave 1
(4) Fourth Spatial Stream: supporting four transmitting and receiving antennas, versus just
(2) Multi-User MIMO (Multiple-Input, Multiple Output) support
(3) 160-MHz channel width support; key to increased data rate, essentially double Wave 1
(4) Fourth Spatial Stream: supporting four transmitting and receiving antennas, versus just
three in Wave 1-based products.
Is IEEE 802.11ac the last WiFi standard? Almost certainly not, as wireless technology marches
onward. Several additional 802.11 committees are already huddling to develop future WiFi
standards which, by all indications, will deliver even greater data rates, densities and distances.
Higher frequencies – well above the 5 GHz band of IEEE 802.11ac – are being eyed for future WiFi
standards, as well as data rates up to 100 Gbps.
onward. Several additional 802.11 committees are already huddling to develop future WiFi
standards which, by all indications, will deliver even greater data rates, densities and distances.
Higher frequencies – well above the 5 GHz band of IEEE 802.11ac – are being eyed for future WiFi
standards, as well as data rates up to 100 Gbps.