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Video quality suffers significant degradation when transmitted over error-prone channel, due to packet loss, errors caused by fading in wireless channel and due to the video codec prediction mechanisms. The H.264/AVC standard suggests some new error-resilient features to enable reliable transmission of compressed video signal over lossy packet networks. Two of those new features are the Redundant Slices and the Flexible Macro-Block Ordering (FMO). In this paper we propose a new error-resilient scheme which merges the H.264/AVC FMO feature with a new technique for dynamic allocation of redundant slices depending on the wireless channel fading parameters. We suggest using a unique smart dynamic redundant slices allocation scheme which considers the dynamic wireless channel parameters rather than using the classical standard static allocation. The proposed redundant slice allocation algorithm is based on both Average Fade Duration (AFD), and Level Cross Rate (LCR) channel's characteristics. Moreover, we propose a new Explicit Spiral-Interleaved (ESI) flexible macroblocks ordering technique, which outperforms all other FMO types. The new ESI ordering results in effective error scattering which maximize the number of correctly received macroblocks located around corrupted macroblocks, leading to better error concealment. The proposed scheme greatly improves video transmission quality over lossy wireless transmission channels. Simulations results for wireless channel characterized by Rayleigh fading indicate that the proposed method improves the standard static allocation of redundant slices in terms of PSNR by about 2.5 dB. Performance evaluations show that our approach is especially suited for applications such as video conferencing and mobile TV, where typically a specific main important Region of Interest should be more carefully protected.

We have begun a randomized study of tele-ophthalmology. General practitioners in two participating health centres in the Negev region of Israel, serving a local population of 40,000, were invited to participate. The study group consisted of 50 consecutive patients attending the general eye outpatient clinic and 50 consecutive patients suffering from various retinal diseases attending a hospital outpatient clinic. The initial assessment was carried out via the tele-ophthalmology system. There was then a face-to-face re-examination of the same patients, in randomized order, by the same ophthalmologist on the same day, at an outpatient ophthalmology clinic.

[1] We describe radio wave propagation within terrain with vegetation, based on the measurements performed in a forested areas using low transmitter (TX) and receiver (RX) antenna elevations. We continue to investigate 3-D statistical multiparametric model of radio wave propagation above the rough terrain with some modifications made to describe multiple scattering of the signal field from randomly distributed trees, as phase screens, that model the random structure of trees with the rough surfaces and the irregular structure of branches and leaves, and other roughnesses placed on the ground surface. The scattering effects of trees and roughnesses are considered using a statistical description of an array of randomly distributed screens placed on a rough terrain. At the same time, an empirical short-range path loss model which is based on measurements carried out in typical forested areas in Denmark is considered. Comparison between results obtained from the statistical and the empirical models and those obtained from examination of the experimental data, as well as with the results of other existing models, is presented. It is shown that both models predict the exponential field intensity decay with the wide range of the power law index variations (from -2.5 to -4.3) with accuracy Ϯ6 dB with respect to experimental data and which is better than that obtained from other existing theoretical models.