2030101030017 ; 電機工程學系 ; Roaming across multiple basic service sets (BSS) using access points (APs) in wireless LAN (WLAN) always pose considerable challenges, as it will cause heavy packet loss error. Especially for real-time video streaming, it will damage receiving video quality. In this paper, we combine the benefits of multiple descriptions coding (MDC) and multipath routing to maintain a best constant video quality despite packet loss when roaming in WLAN. By incorporating channel status detection mechanism to decide which channel will be selected or multiple channels will be used to take advantage of path diversity to deliver the streaming video content. The loss-rate and round-trip time are used to determine the channel status by using active probing. Simulation results indicate that the proposed method can significantly improve the quality of streamed video when mobile client roams in WLAN.