802.11ac PHYs ================ .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the PHY in IEEE 802.11ac?** The PHY (Physical Layer) in 802.11ac is responsible for transmitting and receiving data over the wireless medium using advanced radio technologies. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What modulation does 802.11ac use?** 802.11ac uses OFDM with modulation types including BPSK, QPSK, 16-QAM, 64-QAM, and 256-QAM for higher data rates. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is OFDM in 802.11ac?** OFDM divides the wireless channel into multiple orthogonal subcarriers that transmit data simultaneously, improving throughput and robustness. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How many subcarriers are used in 802.11ac OFDM?** Depending on channel width, 802.11ac uses 52 subcarriers for 20 MHz channels, up to 234 subcarriers for 80 MHz, and 468 subcarriers for 160 MHz channels. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What coding technique is used in 802.11ac PHY?** It uses convolutional coding and optionally LDPC (Low-Density Parity-Check) coding for enhanced error correction. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is LDPC in 802.11ac?** LDPC is an advanced error-correcting code that improves data reliability and throughput compared to traditional convolutional coding. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What data rates are supported by 802.11ac PHY?** 802.11ac supports data rates from around 6.5 Mbps up to several Gbps depending on channel width, MIMO streams, and modulation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Which modulation corresponds to the highest data rate in 802.11ac?** 256-QAM modulation combined with multiple spatial streams and wide channels achieves the highest throughput. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the channel width in 802.11ac?** 802.11ac supports 20 MHz, 40 MHz, 80 MHz, and optionally 160 MHz channel widths for wider bandwidth and higher speeds. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is MU-MIMO in 802.11ac?** Multi-User MIMO allows simultaneous data transmission to multiple devices using multiple antennas, increasing network efficiency. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How many spatial streams does 802.11ac support?** Up to 8 spatial streams can be used to increase throughput, depending on device capabilities. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is beamforming in 802.11ac?** Beamforming focuses the radio signal toward specific clients to improve signal quality and range. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the OFDM symbol duration in 802.11ac?** Similar to 802.11a/n, around 4 microseconds per OFDM symbol, including a guard interval. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the guard interval in 802.11ac?** 802.11ac supports both standard 800 ns and optional short 400 ns guard intervals for reduced latency and increased throughput. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What FFT size is used in 802.11ac?** The FFT size scales with channel width: 64 points for 20 MHz, 128 for 40 MHz, 256 for 80 MHz, and 512 for 160 MHz. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11ac PHY handle multipath effects?** OFDM, beamforming, and advanced error correction reduce multipath interference in dense environments. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11ac PHY full-duplex?** No, 802.11ac operates in half-duplex mode like other Wi-Fi standards. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the PHY preamble in 802.11ac?** The preamble contains training fields used for synchronization, channel estimation, and beamforming feedback. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11ac PHY support backward compatibility?** It supports backward compatibility with 802.11a/n devices via mixed mode operation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11ac use dynamic rate adaptation?** Yes, it dynamically adjusts modulation, coding, and spatial streams based on channel conditions. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What limits the range of 802.11ac?** Like 802.11a/n, 802.11ac uses 5 GHz, which has shorter range and less wall penetration compared to 2.4 GHz. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11ac PHY widely used today?** Yes, it remains common in many modern Wi-Fi devices and access points for high-speed wireless networking. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links ` .. _phy_ac_step17: .. tab-set:: .. tab-item:: Reference links * Reference links