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— We present a new cross-layer ARQ algorithm for video streaming over 802.11 wireless networks. The algorithm combines application–level information about the perceptual and temporal importance of each packet into a single priority value, which drives packet selection at each retransmission opportunity. Hence, only the most most perceptually important(More)
The H.264/SVC video codec extends the H.264/AVC standard with scalability features. In this paper we introduce a traffic prioritization algorithm suitable for the transmission of both H.264/SVC and H.264/AVC video over 802.11e ad hoc wireless networks. The proposed algorithm exploits the traffic prioritization capabilities offered by 802.11e to provide(More)
The paper aims at evaluating a number of Quality of Service (QoS) indices of a real-time video transmission over an 802.11 ad hoc wireless network. Video is coded according to the state-of-the-art ITU-T H.264 encoder and its transmission is simulated by means of the ns network simulator. Objective quality measurements are presented. Moreover, the impact of(More)
Recommended by Zhu Han This work presents an application-level perceptual ARQ algorithm for video streaming over 802.11e wireless networks. A simple and effective formula is proposed to combine the perceptual and temporal importance of each packet into a single priority value, which is then used to drive the packet-selection process at each retransmission(More)
— We present a technique to enhance real-time video transmissions over 802.11-based ad hoc networks. We propose to limit the coverage of the error detection mechanism to the most error sensitive bit class contained in video packets. Packets are retransmitted only if errors affect those bits, instead of re-transmitting all corrupted packets irrespective of(More)
This work addresses the implications of using the Time-Division Unbalanced Carrier Sense Multiple Access (TDuCSMA) coordination function to support triple-play services. Firstly, the theoretical background of TDuCSMA is reported, presenting its advantages and discussing its full compliance with the IEEE 802.11 standard. Secondly, a prototype of TDuCSMA is(More)
— This paper evaluates the performance of video streaming in inter-vehicular environments using the 802.11 ad hoc network protocol. We performed transmission experiments while driving two cars equipped with 802.11b standard devices in urban and highway scenarios. Different sequences, bitrates and packetization policies have been tested. The experiments show(More)
This paper presents an analysis-by-synthesis technique to evaluate the perceptual importance of multimedia packets for rate-distortion optimized streaming. The proposed technique, instead of relying on a priori information, computes the distortion that would be caused by the loss of each single packet, including the effects of error propagation and(More)
We present a new algorithm to dynamically identify perceptually important regions in pictures of a video sequence. For each macroblock, the distortion that its loss would cause at the decoder is computed. High-distortion macroblocks are then grouped together into slices to be protected with forward error correction or to be sent as " premium " packets. We(More)
— We present a new ARQ algorithm for video streaming over wireless channels. The algorithm takes into account the perceptual and temporal importance of each packet to determine the packet scheduling which maximizes the perceived quality. We propose a simple and flexible function to combine the perceptual importance with the real-time constraints of each(More)