An objective figure of merit using peak-signal-to-noise ratio will assess the improvement gains over simpler methods of concealment. Typical rates of algo- rithm convergence are determined. The algorithm is judged on how well it performs with varying degrees of error localization (i.e. We investigate the proposed algorithm by performing simulation on typical video images. The algorithm iterates between satisfying spatial domain and spectral domain constraints, much like Gerchberg's method (91. The POCS method of image restoration attempts to satisfy a priori characteristics typical of most natural video images. In this paper, we introduce a proposed method of error concealment based on projections onto convex sets (POCS) (7). The algorithm is a Gerchberg-type spatial domainkpectral domain constraint-satisfying iterative process, and may be viewed as an alternating projections onto convex sets method. It attempts to utilize spatially correlated edge information from a large local neighborhood of surrounding pixels to restore missing blocks. This paper presents a spatial interpolation algorithm that addresses concealment of lost image blocks using only intra-frame information. Error concealment is aimed at masking the effect of missing blocks by use of tem- poral or spatial interpolation to create a subjectively acceptable approximation to the true error-free image. The resulting image is flawed by the absence of square pixel regions that are notably perceived by human vision, even in real-time video sequences. Prob- lems arising from imperfect transmission of block-coded images result in lost blocks. We show that the proposed mechanism outperforms conventional point-to-point transmission, especially under conditions of high mobility.Īn algorithm for lost signal restoration in block- based still image and video sequence coding is presented. A simulation study was carried out using NS-2 to demonstrate the performance of the proposed mechanism. Furthermore, the use of disjoint routes also enables the workload to be distributed more evenly within the network. Second, the routing protocol is expanded to include finding disjoint routes from video sources to the receiver so that a single link breakage or a single intermediate node failure affects transmission from only the minimum number of nodes. First, Multiple Description Coding (MDC) scheme is used for video coding to reduce the redundancy by avoiding the transmission of duplicate video frames. There are two key features in our proposal.

A novel framework designed with features to accommodate the characteristics of ad hoc networks is presented.

In this paper, we tackle this problem by adopting the concept of multipoint-to-point video transmission used in wire-line networks. However, supporting video applications over mobile ad hoc networks is more complicated than with other networks due to the lack of support from a preinstalled infrastructure. It is predicted that there will be a high demand for video applications in future wireless networks including wireless ad hoc networks. Moreover, we also show that the number of transmission points should be limited because using too many transmission points burdens the network with unnecessary control overhead. Simulation study is carried out using NS-2 to demonstrate the feasibility of the proposed mechanism and it shows that better quality of video streaming is achieved, in terms of fewer and shorter interruptions during the video session. In order to discover maximally disjoint routes for each sender and to distribute the workload evenly within the network, an extension for video applications is added to the dynamic source routing (DSR) protocol. More specifically, we use multipoint-to-point transmission together with Multiple Description Coding to enhance the quality of video streaming. In this paper, we investigate the possibility of implementing server diversity over ad hoc networks. Besides, using disjoint multipath to support video streaming over mobile ad hoc networks has also been widely studied. Path and server diversities are proven feasible to guarantee reliable video delivery wired networks. A considerable amount of research has been done to provide solution for video streaming over lossy networks, among which are the diversity techniques. As mobile ad hoc networks emerge as a promising technology for untethered, ubiquitous service in future communication system, a solution to support increasingly popular video applications is essential. Supporting video applications over mobile ad hoc networks is more challenging than over other best-effort networks due to the lack of a preinstalled infrastructure to provide centralized control for the entire networks.

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