Link adaptation and cross-layer signaling for wireless video-streaming in a shared medium

Changes in the quality of wireless links impose great demands on video codecs and underlying network layers when seamless video-streaming is to be achieved. Moreover, it is not enough that only the video codec or only the radio adapts to these changes; the efforts should he applied in both layers, and - if possible - synchronized. So, on the one hand, a responsive link adaptation method should be employed in the radio. And, on the other hand, the video codec should be able to follow the changes in the maximum throughput due to wireless link performance variations. In this paper we present the results of video-streaming over 802.11a link in the presence of background traffic, generated by other stations sharing the same medium. We show that great improvements in the quality of the video can be achieved by cross-layer signaling between the link layer and the video coder. However, we show that this is only realizable if a correct estimation can he made of the throughput decline due to the medium sharing.