International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The ability to acquire real-time video from flight test platforms is becoming an important requirement in many test programs. Video is often required to give the flight test engineers a view of critical events during a test such as instrumentation performance or weapons separation. Digital video systems are required because they allow encryption of the video information during transmission. This paper describes a Digital Video Telemetry System that uses improved video compression techniques which typically offer at least a 10:1 improvement in image quality over currently used techniques. This improvement is the result of inter-frame coding and motion compensation which other systems do not use. Better quality video at the same bit rate, or the same quality video at a lower bit rate is achieved. The Digital Video Telemetry System also provides for multiplexing the video information with other telemetered data prior to encryption.

In this dissertation, we investigate the capacity and performance of wireless networks with an emphasis on multicast traffic. The defining characteristic of a multicast network is a network where a number of different destinations all require the information generated by a single source. The models that we explore differ in the nature of the nodes from all-mobile case where all nodes are mobile to hybrid case where some nodes are mobile and some are static. We investigate different performance measure for these wireless multicast networks: upper bounds, capacity scaling laws, and achievable rates. The understanding of these measures for such networks helps in the development of efficient algorithms for operating these networks. In addition, we study the practical realization of algorithms for real-time streaming of rich multimedia content in the context of mobile wireless networks for embedded and cyberphysical systems. Our initial work is in the context of unicast and multiple unicast systems over an autonomous aerial vehicle (AAV) network. Bandwidth requirements and stringent delay constraints of real-time video streaming, paired with limitations on computational complexity and power consumptions imposed by the underlying implementation platform, make cross-layer and cross-domain co-design approaches a necessity. In this dissertation, we propose a novel, low-complexity rate-distortion optimized (RDO) protocol specifically targeted at video streaming over mobile embedded networks. First, we test the performance of our RDO algorithm on simulation models developed for aerial mobility of multiple wirelessly communicating AAVs. Second, we test the performance of our RDO algorithm and other proposed adaptive algorithms on a real network of AAVs and present a comparative study between these different algorithms. Note that generalizing these algorithms to multicast settings is relatively straightforward and thus is not highlighted to a great degree in this thesis. / text

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Acquiring real-time video data, during flight testing, has become an integral component in aircraft design and performance evaluation. This unique data acquisition capability has been successfully integrated into the JSF (Joint Strike Fighter), CAIS compliant, FTIDAS (Flight Test Instrumentation Data Acquisition System) developed by L-3 Communications Telemetry-East.

This work focuses on improving video transmission quality over a mobile link. More specifically, the impact of buffering and link outages on the freeze probability of transmitted videos is studied. It introduces a new fluid flow model that provides an approximation of the freeze probability in the presence of play-out hysteresis. The proposed model is used to study the impact of two streaming buffer sizes over different possible combinations of outage parameters (data channel on/off times). The outcome of this thesis shows that outage parameters play a dominant role in freezing of streaming video content, and that an increase in these parameters cannot be easily compensated for by an increase in the size of the receiving buffer. Generally, in most cases when there is a variation in outage parameters, an increased buffer size has a negative impact on the freeze probability. To lower the probability of freeze during video playback over a weak mobile link, it is better to sacrifice resolution just to keep the video content playing. Similarly, shifting focus from off to on times brings better results than increasing buffer size.

There is an increasing demand to support high data rate multimedia applications over the current day wireless networks which are highly prone to errors. Relay channels, by virtue of their spatial diversity, play a vital role in meeting this demand without much change to the current day systems. A compress-forward relaying scheme is one of the exciting prospects in this regard owing to its ability to always outperform direct transmission. With regards to video transmission, there is a serious need to ensure higher protection for the source bits that are more important and sensitive. The objective of this thesis is to develop a practical scheme for transmitting video data over a relay channel using a compress-forward relaying scheme and compare it to direct and multi-hop transmissions. We also develop a novel scheme whereby the relay channel can be used as a means to provide the required unequal error protection among the MPEG-2 bit stream. The area of compress-forward (CF) relaying has not been developed much to date, with most of the research directed towards the decode-forward scheme. The fact that compress-forward relaying always ensures better results than direct transmission is an added advantage. This has motivated us to employ CF relaying in our implementation. Video transmission and streaming applications are being increasingly sought after in the current generation wireless systems. The fact that video applications are bandwidth demanding and error prone, and the wireless systems are band-limited and unreliable, makes this a challenging task. CF relaying, by virtue of their path diversity, can be considered to be a new means for video transmission. To exploit the above advantages, we propose an implementation for video transmission over relay channels using a CF relaying scheme. Practical gains in peak signal-to-noise ratio (PSNR) have been observed for our implementation compared to the simple binary-input additive white Gaussian noise (BIAWGN) and two-hop transmission scenarios.

This thesis proposes a strategy for enhancing the efficiency of scalable H.264/AVC video transmission over multi-input multi-output (MIMO) and cooperative communication systems. For scalable video coding (SVC) transmission over MIMO wireless systems, a channel selection algorithm is used to enhance transmission rate. The proposed algorithm allows SVC layers to select channels individually in wireless MIMO systems based on channel state information for transmission rate enhancement. Here, this difficult problem is converted into a mathematical optimization problem to improve SVC performance during video transmission. Experimental results show that the proposed method achieves a higher transmission rate over MIMO systems compared to the existing scheme. For SVC transmission over cooperative communication systems, the algorithm allows each SVC layer to choose an appropriate relay based on channel conditions and SVC layer priority. Thus, SVC data is protected effectively. Experimental results show that video quality obtained by the algorithm exceeds that of non-cooperative systems.

There is an increasing demand to support high data rate multimedia applications over the current day wireless networks which are highly prone to errors. Relay channels, by virtue of their spatial diversity, play a vital role in meeting this demand without much change to the current day systems. A compress-forward relaying scheme is one of the exciting prospects in this regard owing to its ability to always outperform direct transmission. With regards to video transmission, there is a serious need to ensure higher protection for the source bits that are more important and sensitive. The objective of this thesis is to develop a practical scheme for transmitting video data over a relay channel using a compress-forward relaying scheme and compare it to direct and multi-hop transmissions. We also develop a novel scheme whereby the relay channel can be used as a means to provide the required unequal error protection among the MPEG-2 bit stream. The area of compress-forward (CF) relaying has not been developed much to date, with most of the research directed towards the decode-forward scheme. The fact that compress-forward relaying always ensures better results than direct transmission is an added advantage. This has motivated us to employ CF relaying in our implementation. Video transmission and streaming applications are being increasingly sought after in the current generation wireless systems. The fact that video applications are bandwidth demanding and error prone, and the wireless systems are band-limited and unreliable, makes this a challenging task. CF relaying, by virtue of their path diversity, can be considered to be a new means for video transmission. To exploit the above advantages, we propose an implementation for video transmission over relay channels using a CF relaying scheme. Practical gains in peak signal-to-noise ratio (PSNR) have been observed for our implementation compared to the simple binary-input additive white Gaussian noise (BIAWGN) and two-hop transmission scenarios.

Bandwidth-intensive video streaming applications occupy an overwhelming fraction of bandwidth-limited wireless network traffic. Compressed video data are highly structured and the psycho-visual perception of distortions and losses closely depends on that structure. This dissertation exploits the inherent video data structure to develop perceptually-optimized transmission paradigms at different protocol layers that improve video quality of experience, introduce error resilience, and enable supporting more video users. First, we consider the problem of network-wide perceptual quality optimization whereby different video users with (possibly different) real-time delay constraints are sharing wireless channel resources. Due to the inherently stochastic nature of wireless fading channels, we provide statistical delay guarantees using the theory of effective capacity. We derive the resource allocation policy that maximizes the sum video quality and show that the optimal operating point per user is such that the rate-distortion slope is the inverse of the supported video source rate per unit bandwidth, termed source spectral efficiency. We further propose a scheduling policy that maximizes the number of scheduled users that meet their QoS requirement. Next, we develop user-level perceptual quality optimization techniques for non-scalable video streams. For non-scalable videos, we estimate packet loss visibility through a generalized linear model and use for prioritized packet delivery. We solve the problem of mapping video packets to MIMO subchannels and adapting per-stream rates to maximize the total perceptual value of successfully delivered packets per unit time. We show that the solution enables jointly reaping gains in terms of improved video quality and lower latency. Optimized packet-stream mapping enables transmission of more relevant packets over more reliable streams while unequal modulation opportunistically increases the transmission rate on the stronger streams to enable low latency delivery of high priority packets. Finally, we develop user-level perceptual quality optimization techniques for scalable video streams. We propose online learning of the mapping between packet losses and quality degradation using nonparametric regression. This quality-loss mapping is subsequently used to provide unequal error protection for different video layers with perceptual quality guarantees. Channel-aware scalable codec adaptation and buffer management policies simultaneously ensure continuous high-quality playback. Across the various contributions, analytic results as well as video transmission simulations demonstrate the value of perceptual optimization in improving video quality and capacity. / text

Teleoperations is a significant field in robotics research; its applications range from emergency rooms in hospitals to space station orbiting the Earth to Mars rovers scavenging the red planet for microscopic life. We have developed a new user defined selective video object plane scheme. This selective filter works with standard H.264 encoder which is developed using Intel IPP and uses the latest multicore capabilities of new processors and can encode and transmit high definition videos over internet in real time. The area of interest is extracted and encoded at a different frame rate and noise level than rest of the frame. Our modified algorithm uses user input as well as motion detection of individual pixels to define video object plane. Video object plane filter is designed to be used for video with slow moving objects for cases like surgical procedures. The results of our compression algorithm have been verified using SSIM, PSNR and human perception survey. All these results of our VOP showed better performance than comparable encoders at the same bandwidth.

Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: H.264; PSNR; Error Control; RPS; Retransmission; VQM. Includes bibliographical references (leaves 149-160).