電機工程學系 ; Video transport over Wireless LANs (WLANs) may suffer from signal fading, noise interference, and network congestion which will cause packet loss or packet error. Should a packet loss occur in some frame, it will not only affect the corresponding frame but may also lead to error propagation to the following frames until reaching the next intra-coded frame. In addition, the bandwidth of WLAN is usually far less than that of wired networks, thus protection mechanisms for error control has an innate limitation. In this paper, we first propose a scheme to estimate the error propagation effect of a concealed lost packet. Consider the error-prone characteristic of WLANs and the scenario under limited resource; we propose a prioritized retransmission mechanism to protect against the bursty packet losses in WLAN environments. Experimental results show that the proposed method can usually significantly improve the quality of video streaming over WLANs as compared to play-out deadline-based methods.