802.11ac Overview

The P802.11ac standard is an enhancement of the 802.11n-2009 standard (see 802.11n HT OFDM Overview) to improve data throughput capabilities of 802.11 wireless LANs and provide better support for multiple users and multiple data streams.

The VSA can demodulate 802.11ac signals that adhere to IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org P802.11ac/D2.0.

802.11ac adds the following features:

additional signal bandwidths of 80 and 160 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second.
an 80+80 MHz non-contiguous channel bandwidth mode
256-QAM Quadrature Amplitude Modulation modulation for data subcarriers
increased maximum number of spatial streams from four to eight
support for multiple user transmission for up to four users

80+80 MHz Mode

The non-contiguous 80+80 MHz mode splits the signal into two separate 80 MHz bands which are not contiguous in frequency. For the purpose of transmitter testing, these two signals can be thought of as independent 80 MHz signals which can be demodulated separately (each 80 MHz signal contains enough information in the preamble for a receiver to demodulate it without even seeing the other 80 MHz signal).

This mode supports a 2-channel SISO measurement. It does not support a MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. measurement.

Frame formats

Unlike 802.11n that has two HT high throughput frame formats, 802.11ac only defines only one VHT very high throughput (VHT) physical (PHY) layer protocol data unit (PPDU):A PPDU transmitted using the TXVECTOR FORMAT parameter equal to VHT. frame format which is similar to HT-mixed where the burst starts with the legacy preamble and is followed by a VHT preamble.