QoS Support Of Scalable Video Transmission Over Wireless Networks Through Cross-layer Design

With the rapid development of the wireless networks,more and more multimedia application based on wireless networks are now emerged. However, the characteristics of the wireless networks restricted the development of such applications.Therefore, how to transport video traffic reliably in wireless networks is a hot research topic.At present, as the extention of H.264/AVC standard, H.264/SVC has the advantage of scalability and adaptability. This thesis considers the scalability of H.264/SVC and the QoS guarantee scheme of IEEE 802.11e, a combination of both would ensure the QoS of the video transmission in Wireless Network with IEEE 802.11e MAC protocol. Based on the study of the structure of the video coding and network characteristics, this thesis proposed a new cross-layer mapping scheme to ensure the QoS of the video transmission in Wireless Network.This thesis studies the decoding dependency of the scalable video firstly, then by combining this dependency and the QoS priority of IEEE 802.11e, adopts a cross-layer mapping scheme to ensure the QoS of video transport. The contribution of this thesis is: Different queue threshold is assigned to packets of different SVC video layers; based the importance of different SVC video layers, some low priority video packets of a frame will be dropped when the queue is congested.The performance of the proposed cross-layer mapping mechanism is evaluated by using NS-2 simulator over a simple Wireless Network topology. Through the comparison with static mapping and adaptive mapping, the proposed mechanism can better ensure the video packets transport, thus ensuring the quality of the decoded video. The superiority of this mechanism is mainly because it can drop some low priority packets according the congestion of the queue.