CWNA Wireless Network Administrator

Answer - D - The 802.11e amendment defines quality of service (QoS) at the MAC sub-layer.

Key Takeaway: 802.11e is a specification that defines QoS mechanisms for wireless devices that support bandwidth-sensitive applications, such as voice and video. 802.11e enhances the 802.11 MAC layer with a coordinated TDMA construct and adds error-correcting mechanisms for delay-sensitive applications, such as voice and video.