Research Of Multi-path Selection And Automatic Retransmission In Wireless LAN

With the development of computer network and communication technology, the Wireless Local Area Network (WLAN) has become more and more popular. Institute of Electrical and Electronics Engineers has defined a series of WLAN standards such as IEEE 802.11a, 802.11b, 802.11g. WLAN has been implemented in many places as a broadband wireless access technology. Many applications and services have been introduced to the practice and they require much higher quality of wireless transmission. This paper first generalizes the architecture of WLAN and educes the problems of current IEEE standards. The performance of Wireless LAN often suffers from link-layer frame losses. Automatic Repeat reQuest (ARQ) is one of the technologies designed and implemented in the wireless link layer to improve the transmission quality. Three popular kinds of ARQ have been introduced in this paper.Then the research focuses on the characteristics of the wireless transmission. Link-layer frame losses are often caused by noise, interference, multipath, attenuation, and user mobolity. These factors are related to the spatial path of the wireless channel. An experiement has been set up to show that frame losses often occur in burst.Since ARQ is not such efficient for burst losses, the combination of Multi-path Selection and ARQ is a better solution to deal with burst losses and independent losses seperately. The choice of threshold is analyzed in the later discussion. An experiement has been established to prove this solution is efficient for the wireless transmission especially in the mobile situation.