A Survey of QoS Techniques in 802.11
The most important functions of the MAC layer for a wireless network include controlling channel access, maintaining Quality of Service (QoS), and providing security. Wireless links have characteristics that differ from those of fixed links, such as high packet loss rate, bursts of packet loss, packet re-ordering, and large packet delay and packet delay variation. Furthermore, the wireless link characteristics are not constant and may vary in time and place. The mobility of users poses additional requirements, as the end-to-end path may be changed when users change their point of attachment. Users expect to receive the same QoS after they have changed their point of attachment.