Browsing by Author "Sanchez, Pedro"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item H.264/SVC rate-resiliency tradeoff in faulty communications through 802.16e railway networks(2009) Unanue, Iraide; Del Ser, Javier; Sanchez, Pedro; Casasempere, Jon; IA; Centros PRE-FUSION TECNALIA - (FORMER)Focusing on 802.16e-based railway networks, our work deals with the degradation of the perceived quality of multimedia communications in presence of handover events. The movement of mobile nodes (MN) across coverage areas of distinct Base Stations (BS) involves global disconnection periods, which leads to a degradation of the perceived video quality. During this period, video data packets are dropped, and therefore video frame information is lost. The study presented here concentrates on the specific dynamism characteristics of conventional video surveillance applications and the transmission of the recorded video information over 802.16e networks. We conclude, through intensive simulations, that the GOP structure of the H.264/SVC encoded video information should not exclusively emphasize on maximizing the compression rate of the stream. Instead, the utilized GOP structure should be selected according to both the motion pattern of the processed video and the handover statistics of the railway communication channel which, in turn, are extremely predictable in railway scenarios. This conclusion is corroborated by proposing the insertion of intra-period frames into the GOP structure, in order to maximize the average Peak Signal to Noise Ratio (PSNR) of the received stream at a negligible video size penalty cost.Item On the design of a scalable multimedia streaming system based on receiver-driven flow and congestion awareness(2010) Urteaga, Inigo; Unanue, Iraide; Del Ser, Javier; Sanchez, Pedro; Rodriguez, Aitor; IAIn this position paper we present the design of an end-to-end scalable content streaming system that optimizes the quality of experience of the end-user by allowing each client to retrieve a customized multimedia stream, based on both network and client states. By taking advantage of multimedia scalability, our proposed receiver-driven architecture performs a multilayered streaming, where each client is responsible for controlling the number of multimedia layers it demands from the server. Furthermore, the streaming system proposed herein implements both congestion and flow control mechanisms, which are also delegated to the receiver. In order to properly address both network and client states and restrictions, a set of specific metrics (Buffer State, Interarrival Jitter and Loss Event Rate) are utilized, which have been specifically designed to match the miscellaneous characteristics of heterogeneous networks and end devices. Built upon such metrics, we present a decision algorithm that jointly performs congestion and flow control, while maximizing inter-session fairness and end-user quality of experience. The proposed architecture combines different standard protocols while guaranteeing independence between components of the streaming system.Item Performance evaluation of H.264/MPEG-4 scalable video coding over IEEE 802.16e networks(2009) Casasempere, Jon; Sanchez, Pedro; Villameriel, Tomas; Del Ser, Javier; Centros PRE-FUSION TECNALIA - (FORMER); IAThis work considers the transmission of multimedia streams over broadband networks using the latest video coding standard H.264/SVC. The Scalable Video Coding for Heterogeneous Media Delivery allows temporal, spatial and SNR scalability in video flows, adapting and optimizing the quality of the received media according to the wireless channel conditions. In this paper an evaluation platform combining NS-2 and real video coding has been designed in order to evaluate the performance of H.264/SVC over 802.16e networks in railway environments. Extensive computer simulations have been done to compare the quality of service (QoS) of our scheme with respect to other video coding techniques in terms of jitter, delay or Peak Signal to Noise Ratio (PSNR). The obtained simulation results state that, in terms of the considered metrics, H.264/SVC outperforms other existing standards (i.e. MPEG-4, H.263 and H.264) in terms of the considered metrics when used in railway communications.