Throughput Analysis , Improvement and QoS Differentiation in Contention Based IEEE 802.11(e) WLANs

• Main Authors: TSUNG-CHE WU, 吳宗哲
• Other Authors: JENG-JI HUANG
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/9b9ruj

碩士 === 國立臺灣師範大學 === 應用電子科技學系 === 97 === Both IEEE 802.11 and IEEE 802.11e define a mechanism apiece for stations to contend for channel resources without arrangement in advance. In this thesis we focus on the contention-based mechanisms and present three studies on them. In the first part, a novel model is proposed by considering the transmission probability of a specific station will increase or decrease after each time slot, and, based on this model, the throughput of 802.11 DCF is analyzed. Secondly, the 802.11 DCF mechanism is modified to improve its throughput in a hybrid environment by adding an extra part in front of every data packet using the basic access mechanism to protect it from collision with RTS packet(s). Finally, the contention window is adaptively adjusted in 802.11e EDCA, in order that the portion of QoS received by each service class under channel errors will remain the same as that under error-free channels.