While 802.11n was a revolutionary enhancement over 802.11a/g, and necessitated an entire book for proper presentation of the new technology, 802.11ac is more of an evolutionary improvement over 802.11n by providing wider bandwidth channels and multi-user MIMO. As such we felt that the treatment of new 802.11ac features could be addressed by a few extra chapters in an update of our original 802.11n book, now an 802.11n/ac book.

The new single user Very High Throughput physical layer packet structure is described in a new Chapter 7, including a description of 80 MHz and 160 MHz waveforms. The new downlink multi-user MIMO mechanism in 802.11ac is presented in a new Chapter 14. Enhancements to channel access for 802.11ac have been added to Chapter 11. Several new basic service set and clear channel assessment rules to manage 80 MHz and 160 MHz operation and coexistence are described in Chapter 11. Modifications to 802.11n channel model Doppler component are given in Chapter 3 and Chapter 13. Furthermore, we discuss the simplification of single user transmit beamforming in 802.11ac in Chapter 13.