Suchergebnisse

Mobile Adhoc Networks (MANETs) are open to a wide range of attacks due to their unique characteristics like dynamic topology, shared medium, absence of infrastructure, and resource constraints. Data packets sent by a source node may reach destination through a number of intermediate nodes. In the absence of security mechanism, it is easy for an intermediate node to intercept or modify the messages, thus attacking the normal operation of MANET. One such attack is Black hole attack, in which, a malicious node called Black hole node attracts all the traffic of the network towards itself, and discards all the packets without forwarding them to the intended recipients. This paper evaluates the performance of Adhoc on-demand Distance Vector (AODV) and its multi-path variant Adhoc On-demand Multi-path Distance Vector (AOMDV) routing protocols under black hole attack. Non-cryptographic solutions Secure Blackhole AODV (SBAODV) and Secure Blackhole AOMDV (SBAOMDV) have been proposed to mitigate the effect of black hole attack. Through NS-2 simulations, the performance of the proposed protocols with video streaming is analyzed. The results show that the proposed solutions provide better performance than the conventional AODV and AOMDV.

This research work was partially funded by the Strategic Educational Pathways Scholarship Scheme (STEPS-Malta) and by European Union - European Social Fund (ESF 1.25). ; Bandwidth-limited channels demand the transmission of the per-pixel depth maps with the texture data to provide immersive 3D video services that allow arbitrary 3D viewpoint reconstruction. This auxiliary depth data offers geometric information, which together with the multi-view and epipolar geometries, can be exploited during 3D video coding to calculate geometric positions for the search areas of disparity estimation. These positions represent a more accurate estimate match to compensate the current macro-block from than those provided by the median adopted by the H.264/MVC standard. The result is smaller search areas that reduce the encoder's computational requirement. In this work, we exploit this fact together with the largest depth variation within the macro-block to encode, to calculate and adaptively adjust these areas along the epipolar lines. The proposed solution achieves a speedup gain of up-to 32 times over the original disparity estimation, with negligible influence on the rate-distortion performance of 3D video coding. This highly reduces the computational cost of the H.264/MVC encoder and eases its need to be implemented on highly expensive systems that are otherwise necessary to meets the stringent latency requirement of broadcast transmissions. Moreover, it provides similar coding efficiencies required for such scenarios. ; peer-reviewed

Wireless Multimedia Sensor Networks (WMSNs) promise a wide scope of emerging potential applications in both civilian and military areas, which require visual and audio information to enhance the level of collected information. The transmission of multimedia content requires a minimal video quality level from the user's perspective. However, links in WMSN communi- cations are typically unreliable, as they often experience fluctuations in quality and weak connectivity, and thus, the routing protocol must evaluate the routes by using end-to-end link quality information to increase the packet delivery ratio. Moreover, the use multiple paths together with key video metrics can enhance the video quality level. In this paper, we propose a video-aware multiple path hierarchical routing protocol for efficient multimedia transmission over WMSN, called video-aware MMtransmission. This protocol finds node-disjoint multiple paths, and implements an end-to-end link quality estimation with minimal over- head to score the paths. Thus, our protocol assures multimedia transmission with Quality of Experience (QoE) and energy-efficiency support. The simula- tion results show the benefits of video-aware MMtransmission for disseminating video content by means of energy-efficiency and QoE analysis.

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. J. C. San Miguel, and J. M. Martínez, "On the effect of motion segmentation techniques in description based adaptive video transmission", in AVSS '07: Proceedings of the 2007 IEEE Conference on Advanced Video and Signal Based Surveillance, 2007, p. 359-364 ; This paper presents the results of analysing the effect of different motion segmentation techniques in a system that transmits the information captured by a static surveillance camera in an adaptative way based on the on-line generation of descriptions and their descriptions at different levels of detail. The video sequences are analyzed to detect the regions of activity (motion analysis) and to differentiate them from the background, and the corresponding descriptions (mainly MPEG-7 moving regions) are generated together with the textures of the moving regions and the associated background image. Depending on the available bandwidth, different levels of transmission are specified, ranging from just sending the descriptions generated to a transmission with all the associated images corresponding to the moving objects and background. We study the effect of three motion segmentation algorithms in several aspects such as accurate segmentation, size of the descriptions generated, computational efficiency and reconstructed data quality. ; This work is partially supported by Cátedra Infoglobal-UAM para Nuevas Tecnologías de video aplicadas a la seguridad. This work is also supported by the Ministerio de Ciencia y Tecnología of the Spanish Government under project TIN2004-07860 (MEDUSA) and by the Comunidad de Madrid under project P-TIC-0223-0505 (PROMULTIDIS).