Adaptive end-to-end optimization of mobile video streaming using QoS negotiation

Video streaming over wireless links is a non-trivial problem due to the large and frequent changes in the quality of the underlying radio channel combined with latency constraints. We believe that every layer in a mobile system must be prepared to adapt its behavior to its environment. Thus layers must be capable of operating in multiple modes; each mode will show a different quality and resource usage. Selecting the right mode of operation requires exchange of information between interacting layers. For example, selecting the best channel coding requires information about the quality of the channel (capacity, bit-error-rate) as well as the requirements (latency, reliability) of the compressed video stream generated by the source encoder. In this paper we study the application of our generic QoS negotiation scheme to a specific configuration for mobile video transmission. We describe the results of experiments studying the overall effectiveness, stability, and dynamics of adaptation of our distributed optimization approach

Quality of Service Controlled Adaptive Video Coding over IEEE 802.11 Wireless Links

In this paper we present the initial results of experiments where encoded video data is transmitted over an IEEE 802.11a wireless link. The changing link state and the perhaps changing constraints imposed by mobile device or user, will move the optimal settings of both the video encoder and the IEEE 802.11 network layer. The video encoder and the network layer will negotiate their options facilitated by a Quality of Service negotiation scheme called "Adaptive Resource Contracts", thereby jointly optimizing their parameters. When time is a constraint, this optimization has to be fast and simple, maybe even at the cost of finding suboptimal solutions, as long as the found settings will give a better Quality of Service than fixed parameter settings