Rate adaptivity is an important concept in data intensive applications such as video communications. In this paper, we
present an example rate adaptive, live, video communications system over IEEE 802.11 wireless networks, which
integrate channel estimation, rate adaptive video encoding, wireless transmission, reception, and playback. The video
stream over the wireless network conforms to the RTP payload format for H.264 video, and can be retrieved and
displayed by many popular players such as QuickTime and VLC. A live, video-friendly, packet-dispersion-based
algorithm will be used to estimate the available bandwidth, which is then used to trigger rate control to achieve rate
adaptive video coding on the fly.