Abstract
The IEEE 802.11 wireless Local Area Network (LAN) provides high bandwidth for data transmission in low tier wireless networks. However, the access method of IEEE 802.11 cannot meet the Quality of Service (QoS) requirements for all kinds of traffics. In this paper, we propose some modifications and mechanisms for the IEEE 802.11 Medium Access Control (MAC) protocol to provide the QoS guarantee according to the characteristics of the traffic. We adopt four different traffic classes: namely conversational class, streaming class, interactive class, and background class proposed, by the UMTS [3]. The Connection Admission Control (CAC) and the scheduling algorithm provide the guarantee of the QoS requirements for real-time traffic (conversational and streaming classes) based on the polling in Point Coordination Function (PCF) mode and for non-real-time traffic (interactive and background classes) based on the modified CSMA/CA with different access priorities in the DCF mode.