Energy Efficiency and Goodput Enhancement of IEEE 802.11a Wireless LAN via Dynamic Fragmentation and Link Adaptation

• Main Authors: Chia-Liang Zhuo, 卓家良
• Other Authors: Jyh-horng Wen
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/47095748664246590426

碩士 === 國立中正大學 === 通訊工程研究所 === 94 === In recent years, wireless local area network (WLAN) has received significant attention from the industry and academia because it enables users, wherever they are, to get abundant information from Internet. WLAN not only offers quite a few advantages, but also raises potential research issues, such as link adaptation, power control and channel estimation. This thesis will focus on fragmentation and link adaptation for further discussions and researches. In the fragmentation scheme of IEEE 802.11 standard, if the size of the MSDU (Media Access Control Service Data Units) is larger than the fragmentation threshold, it is divided into several equal sections of smaller MPDUs (Media Access Control Protocol Data Units). Many previous researches only considered a single fragmentation threshold and link adaptation scheme in order to improve network performances. Although transmitter can adjust the transmission rate dynamically based on channel information, it transmits the same number of bits for each transmission packet due to single fragmentation threshold. This way, however, leads to a limit improvement of network performance. In order to make a significant improvement, in this thesis, we propose dynamic fragmentation and link adaptation algorithm. In the proposed algorithm, multiple fragmentation thresholds, instead of a single one, can be selected according to different transmission rates when a particular target packet error occurs. Under this circumstance, the channel is able to be more effectively utilized as well. We simulate the proposed algorithm under log-normal shadowing channel model and the results show that the proposed algorithm achieves much better performances than other link adaptation schemes.