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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)
—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)
— The IEEE 802.11 MAC standard currently tolerates no errors in delivered packets. In this paper we study the performance of an error tolerant extension to the standard MAC that exploits the unequal perceptual importance of speech bitstreams. More in detail, we differentiate the CRC coverage on the speech payload in order to enable the delivery of partially(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 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)
With the rapid deployment of wireless LANs and the future development of mobile ad hoc networks, multi-hop wireless communications links are expected to become much more common. How to achieve reliable and efficient, yet secure, voice communication over such multi-hop wireless links is an important issue. This paper proposes and investigates a combination(More)
In this paper, we analyze a standard compatible error correction technique for multimedia transmissions over 802.11 WLANs that exploits, when available, the information of previous erroneous transmissions. The basic idea is to store erroneous frames for error correction purposes. More specifically, at the receiver each bit is estimated with a majority(More)
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