Electrical and Computer Engineering Department-College of Engineering-Sultan Qaboos University Quality of Service for Voice IP in Wireless Local Area Network Wadheh Hafidh AL Manthari Abstract Applying voice communication in Wireless Local Area network (WLAN) is a challenging task. This is because of the strict requirement of voice communication in term of delay and bandwidth. In order to fulfill these requirements, IEEE (Institute of Electrical and Electronic Engineers) has developed the 802.1 l e standard to address the Quality of Service (QoS) requirements in WLAN. This thesis utilizes OPNET modeler to program and simulate the Enhanced Distributed Channel Access (EDCA); which is the traffic priority technique of the 802.lle IEEE standard. Four priority levels were set for the different traffic types with the voice traffic having the highest priority. Several scenarios of network setups were simulated in order to evaluate the performance of the newly programmed QoS under different conditions. Assigning the highest priority to the voice traffic allowed the voice traffic to have the smallest media access delay, lowest number of backoff slots and retransmission attempts while maintaining high throughput. These results helped utilizing the WLAN for voice communication.