Analysis of frame aggregation A-MPDU technique in IEEE802.11n WLAN

number: 
2854
إنجليزية
Degree: 
Author: 
Mustafa Samih Hamoudi
Supervisor: 
Dr. Emad H. Al-Hemiary
year: 
2012
Abstract:

This thesis simulates and analyses the frame aggregation techniques introduced in IEEE802.11n Wireless Local Area Network (WLAN) standard. The frame aggregation technique is a method of concatenating Media Access Control (MAC) frames together over a designed aggregation time, to reduce transmission time and increase throughput.On the other hand, Transmission Control Protocol (TCP) is very important as it ensures reliability by self-clocking mechanisms whereby TCP acknowledgments prompt the release of new data segments onto the medium. It is therefore necessary to study the interaction of TCP mechanisms with MAC frame aggregation. Simulation in this thesis is carried out using Network Simulator (NS-2).Different simulations is implemented on the proposed scenario are implemented where throughput and delay are the performance measure. It has been found that a throughput of 68 Mbps is achieved with Single input Single output (SISO) for a window size of 2 Kbyte and aggregation size of 64 Kbyte, the application used in the simulation is File Transfer Protocol (FTP). Regarding the interaction with TCP, a comparison is made through simulations among different TCP congestion control algorithms, like Reno, NewReno, Vegas, Tahoe, and Selective Acknowledgments (SACK). It has been found that with different aggregation sizes, NewReno and SACK outperform the other techniques. As an example a throughput of 80 Mbps is achieved with TCP NewReno and window size of 8 Kbyte. Finally, TCP Vegas shows constant throughput versus offered network load due to the dependencies of Vegas on Round Trip Time (RTT) that may worsen the performance of TCP over wireless MAC aggregated links.