List and describe three technologies in 802.11ac.
What will be an ideal response?
Spectrum. 802.11ac will operate in the less-crowded 5 GHz spectrum. It will not support
the 2.4 GHz spectrum.
Increased channel bandwidth. Whereas 802.11n uses channels up to 40-MHz-wide channels, the 802.11ac standard uses channel bandwidths up to 80 MHz. To achieve this, it was necessary to adapt automatic radio tuning capabilities so that higher bandwidth channels are only used when necessary in order to conserve spectrum use.
MU-MIMO. A variation of MIMO known as Multi-User MIMO (MU MIMO) is implemented in 802.11ac. MU-MIMO enables the simultaneous transmission of different data frames to different clients. This requires that equipment is able to utilize the spatial awareness of the different remote users. It also implements sophisticated queuing systems that can take advantage of opportunities to transmit to multiple clients when the conditions are right.
Error correction coding. Advances in chip manufacturing technology have enabled designers to take advantage of additional levels of processing power so that more sensitive coding techniques that depend on finer distinctions in the received signal can be used. This reduces the number of error correction check bits needed.
Beam forming. Under 802.11n, transmit beam forming (TxBF) was available, but many products did not take advantage of it. With IEEE 802.11ac, TxBF is a standard feature, and all products that implement it will be interoperable. This can result in increased range and coverage area.
Improved battery life. Because of its increased speed in file transfers and similar activities, mobile users may find that by using 802.11ac they can increase their battery life (because it takes less time for activities that require the device to draw significant battery power).
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