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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)
We present a technique to enhance the 802.11 link layer effectiveness by changing the scope of the standard 802.11 error detection step for speech packets. More specifically the proposed technique instructs the link layer to retransmit speech packets only if errors are detected in the most perceptually sensitive bit class, instead of plainly retransmit-ting(More)
We present a source-driven approach to packet marking for speech transmission over packet networks implementing the Differentiated Services model. Packets generated by the speech coder are examined: if deemed perceptually critical, they are marked as premium and sent on a " virtual wire; " otherwise, they are sent as regular best-effort traffic. Applied to(More)
—Mobile multimedia applications, the focus of many forthcoming wireless services, increasingly demand low-power techniques implementing content protection and customer privacy. In this paper low complexity perception-based partial en-cryption schemes for speech are presented. Speech compressed by a widely-used speech coding algorithm, the ITU-T G.729(More)
We present an adaptive technique to transmit speech over 802.11 wireless packet networks. According to the proposed scheme, the speech coding rate of a network-driven variable bitrate coder is selected to match the istantaneous wireless channel conditions: higher rates (i.e., larger packets) for low error rates, lower rates (i.e., smaller packets) when the(More)
Mobile multimedia applications, the focus of many forth-coming wireless services, increasingly demand low-power techniques implementing content protection and customer privacy. In this paper a low-complexity, perception-based partial encryption scheme for telephone-bandwidth speech is presented. Speech compressed by a widely-used speech coding algorithm,(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)
The IEEE 802.11 standard currently does not offer support to exploit the unequal perceptual importance of multimedia bitstreams. All packets affected by channel errors, in fact, are simply discarded, irrespective of the position and percentage of corrupted bits. The objective of this paper is to investigate the effect of bit error tolerance in WLAN speech(More)