802.11ac Interface

This chapter describes a structure of a medium access control (MAC) layer, a physical layer convergence procedure (PLCP) sub‐layer, and a physical medium dependent (PMD) sub‐layer. It discusses management frames, control frames, and MAC header structure, in the MAC layer. The management frames indicate that the access point has an 802.11 ac interface by including the very high throughput (VHT) capabilities information element. The PMD sub‐layer improves the rate of the 802.11 ac radio interface relative to the 802.11n interface. The chapter discusses transmission chain, frequency plan, frequency multiplexing, spatial multiplexing, and modulation and coding scheme in PMD sub‐layer. The 802.11 ac interface operates in the Unlicensed‐National Information Infrastructure (U‐NII) band at 5 GHz. On the 802.11n interface, an access point can simultaneously transmit several streams spatially multiplexed to a single station using the Single User ‐ Multiple Input Multiple Output (SU‐MIMO) mechanism.