Video Applications Quality Improvement in Wireless Systems:QoS Negotiation and Rate Control

Internet was based on simple principles, providing only one best-effort service, i.e. without any delay or packet loss guarantee. This service is sufficient for applications such as electronic mail which have no real time constraints. However, video communication needs to be monitored and adapted when it traverses best-effort environment. The transmission of a continuous flow, like streaming video, witness very strict time constraints. That´s why we need services adapted to specific application needs with a guaranteed QoS (quality of service). This paper presents a context-aware mechanism for the improvement of the wireless video applications quality. This can be done by negotiating the desired QoS between the user terminal and the network entities and by adapting the video communication´s rate to the channel´s current situation. The decision regarding the needed QoS parameters and the rate control is based on context information (user´s profile, applications needs and network monitoring)