802.11ad 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 802.11ad?** The PHY (Physical Layer) in 802.11ad handles high-speed wireless transmission using the 60 GHz band with directional communication and ultra-wide channels. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What modulation types are used in 802.11ad?** 802.11ad supports BPSK, QPSK, 16-QAM, and 64-QAM, depending on the physical layer variant and data rate. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How many PHY types exist in 802.11ad?** There are four PHY types: Control PHY, SC PHY, OFDM PHY, and Spread QPSK (SQPSK) PHY, each optimized for different use cases. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is SC PHY in 802.11ad?** Single Carrier PHY (SC PHY) uses single-carrier modulation, offering lower complexity and power consumption, suitable for handheld devices. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is OFDM PHY in 802.11ad?** OFDM PHY uses Orthogonal Frequency Division Multiplexing to achieve higher throughput, especially in less power-sensitive applications. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the bandwidth of 802.11ad PHY channels?** Each channel in 802.11ad is 2.16 GHz wide, far exceeding traditional Wi-Fi channel widths. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How fast is 802.11ad PHY?** It supports data rates up to 6.76 Gbps, depending on modulation and coding scheme. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the role of beamforming in PHY?** Beamforming focuses transmission and reception in specific directions, overcoming high path loss at 60 GHz. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11ad PHY full-duplex?** No, like other Wi-Fi PHYs, it operates in half-duplex mode—transmit and receive occur at different times. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What coding scheme is used in 802.11ad?** LDPC (Low-Density Parity-Check) coding is used for error correction in higher-rate transmissions, improving reliability. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11ad use convolutional coding?** Yes, for lower-rate transmissions (e.g., Control PHY), convolutional coding may be used instead of LDPC. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the Control PHY?** Control PHY supports robust, low-data-rate communication for link establishment and management. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the SQPSK PHY used for?** SQPSK (Spread QPSK) PHY is designed for robust transmission under noisy conditions, using spreading for additional gain. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the symbol rate in 802.11ad SC PHY?** The symbol rate can reach 1.76 Gsymbols/s depending on the modulation and configuration. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the guard interval in OFDM PHY?** Guard intervals in 802.11ad OFDM PHY reduce inter-symbol interference and can vary with configuration. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What FFT size does 802.11ad OFDM use?** The OFDM PHY uses a 512-point FFT for processing 512 subcarriers in the wide 2.16 GHz channel. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does PHY preamble work in 802.11ad?** The preamble includes training fields and synchronization sequences needed for accurate beamforming and channel estimation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11ad PHY support rate adaptation?** Yes, dynamic rate selection is used to switch between modulation and coding schemes based on link quality. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What affects PHY performance in 802.11ad?** Line-of-sight, antenna alignment, interference, and distance all significantly impact PHY layer performance. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the training field in PHY preamble?** It helps establish timing and phase synchronization and is used for beamforming training in directional links. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11ad PHY support MIMO?** No, 802.11ad uses beamforming and directional antennas instead of spatial multiplexing like traditional MIMO. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is spectral efficiency in 802.11ad PHY?** 802.11ad achieves high spectral efficiency due to wide bandwidth and high-order modulation, up to ~3.1 bps/Hz. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is PHY feedback handled?** Receivers provide channel feedback to optimize beamforming and select modulation and coding schemes. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the maximum PHY payload size?** The maximum PSDU (PHY Service Data Unit) size can be over 4,000 bytes, depending on mode and rate. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the MAC-PHY interface?** The MAC layer passes frames to the PHY layer, which encodes, modulates, and transmits them over the 60 GHz band. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does PHY handle interference in 60 GHz?** Directional beams and limited range reduce interference, but PHY must still adapt to reflection and blockage. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does PHY impact power consumption in 802.11ad?** Yes, higher data rates and beamforming require more processing and power—SC PHY is used to save energy. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What makes 802.11ad PHY different from 802.11a?** 802.11ad operates at much higher frequencies, uses wider channels, includes beamforming, and achieves multi-gigabit speeds. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What are typical use cases for 802.11ad PHY?** High-speed short-range applications like wireless docking, VR headsets, and uncompressed video streaming. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11ad PHY backward compatible?** No, it is not backward compatible with lower-frequency Wi-Fi standards like 802.11a/b/g/n/ac. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is 802.11ad PHY still relevant today?** It laid the foundation for 802.11ay and continues to be used in some enterprise and specialty wireless applications. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links ` .. _phy_ad_step17: .. tab-set:: .. tab-item:: Reference links * Reference links