Lately, researchers were trying to put a lot of efforts to enhance the performance of Wireless LANs. IEEE 802.11 algorithm, DCF, was an interesting subject for studies. Most studies were concentrating on avoiding collisions, packets loss, decreasing transmission delay and enhancing the overall performance of the network. Double Increment Double Decrement (DIDD) was introduced as a solution that enhance the performance by applying some changes in the algorithm. The main changes were applied on the Contention Window (CW). IEEE 802.11e introduced a new algorithm (EDCA) that introduces a QoS to the performance and though improves the overall performance of the WLAN This thesis aim is to study the performance of three different MAC algorithms by applying two different scenarios on legacy DCF, DIDD and EDCA. Analyzing different output results and checking the QoS of each algorithm. Simulations are implemented in Network Simulator 2 (ns-2) to simulate the network and communication procedures. By deducing and analyzing the output results of the main simulation, DIDD shows improvements that are slightly better than the legacy DCF, while EDCA shows better results from both DCF and DIDD. Though, EDCA shows a noticeable enhancement in the performance of the WLAN.