This thesis focuses on the interaction between digital video quality and channel coding in a wireless communication system. Digital video is a high-bandwidth, computationally intensive application. The recent allocation of large tracks of spectrum by the FCC has made possible the design and implementation of personal wireless digital video devices for several applications, from personal communications to surveillance. Wireless video research has centered on contextual coding mechanisms; different sections of a video data stream are coded differently based on the perceived importance of the coded bits. Besides the complexity introduced into a system by this type of coding, no metric based solely on physical layer parameters can be used to predict video quality across different system architectures. A tool was built to explore the video/channel coding relationship. This tool simulates a packet-based digital wireless transmission in various noise and interference environments. The basic communications system models the DAVIC (Digital Audio-Visual Council) layout for the LMDS (Local Multipoint Distribution Service) system and includes several error control algorithms and a packetizing algorithm that is MPEG-compliant. This work introduces a statistical approach to monitoring the video quality. The error-event-mean-arrival-rate, lambda_distance, is a metric derived from the physical layer that can be used to predict the expected video quality across systems with different channel coding algorithms. This metric proved to be uniformly consistent in predicting video quality for sequences corrupted by Gaussian and non-Gaussian noise and protected by a variety of error correction techniques. / Master of Science

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.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Tactical unmanned aerial vehicles (UAV’s) can deliver real-time battlefield video directly to the soldier providing unprecedented situational awareness. The video communications system must be compact, lightweight, secure, and easy to deploy without a complicated ground station. Pacific Microwave Research, Inc. is developing a system capable of providing reliable and secure video communications to handheld terminals throughout the theater. PMR’s Coded Orthogonal Frequency Division Multiplex (COFDM) video transmission system is designed for tactical video transmission in battlefield or Military Operations in Urban Terrain (MOUT) environments. Using digital modulation coding, the system provides a very robust link in the mobile environment.

Compressed video bitstream transmissions over wireless networks are addressed in this work. We first consider error control and power allocation for transmitting wireless video over CDMA networks in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. We formulate a combined optimization problem and give the optimal joint rate and power allocation for each of linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors, i.e., the direct-matrix-inversion (DMI) blind detector and the subspace blind detector, in the downlink. We then present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation. We also make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. We employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Finally, we propose an end-to-end architecture for multi-layer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. We propose to use progressive joint source-channel coding to generate operational transmission distortion-power-rate (TD-PR) surfaces. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the ??equal slope?? argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multi-layer video transmission. It is demonstrated through simulations that as the wireless channel conditions change, these proposed schemes can scale the video streams and transport the scaled video streams to receivers with a smooth change of perceptual quality.

The explosive growth of the Internet during the last few years, has been propelled by the TCP/IP protocol suite and the best effort packet forwarding service. However, quality of service (QoS) is far from being a reality especially for multimedia services like video streaming and video conferencing. In the case of wireless and mobile networks, the problem becomes even worse due to the physics of the medium, resulting into further deterioration of the system performance. Goal of this dissertation is the systematic development of comprehensive models that jointly characterize the performance of transport protocols and media delivery in heterogeneous wireless networks. At the core of our novel methodology, is the use of analytical models for driving the design of media transport algorithms, so that the delivery of conversational and non-interactive multimedia data is enhanced in terms of throughput, delay, and jitter. More speciffically, we develop analytical models that characterize the throughput and goodput of the transmission control protocol (TCP) and the transmission friendly rate control (TFRC) protocol, when CBR and VBR multimedia workloads are considered. Subsequently, we enhance the transport protocol models with new parameters that capture the playback buffer performance and the expected video distortion at the receiver. In this way a complete end-to-end model for media streaming is obtained. This model is used as a basis for a new algorithm for rate-distortion optimized mode selection in video streaming appli- cations. As a next step, we extend the developed models for the aforementioned protocols, so that heterogeneous wireless networks can be accommodated. Subsequently, new algorithms are proposed in order to enhance the developed media streaming algorithms when heterogeneous wireless networks are also included. Finally, the aforementioned models and algorithms are extended for the case of concurrent multipath media transport over several hybrid wired/wireless links.

Compressed video bitstream transmissions over wireless networks are addressed in this work. We first consider error control and power allocation for transmitting wireless video over CDMA networks in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. We formulate a combined optimization problem and give the optimal joint rate and power allocation for each of linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors, i.e., the direct-matrix-inversion (DMI) blind detector and the subspace blind detector, in the downlink. We then present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation. We also make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. We employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Finally, we propose an end-to-end architecture for multi-layer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. We propose to use progressive joint source-channel coding to generate operational transmission distortion-power-rate (TD-PR) surfaces. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the ??equal slope?? argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multi-layer video transmission. It is demonstrated through simulations that as the wireless channel conditions change, these proposed schemes can scale the video streams and transport the scaled video streams to receivers with a smooth change of perceptual quality.

Advancements in video coding, compact media display, and communication devices, particularly in emerging broadband wireless access networks, have created many foreseeable and exciting applications of video broadcast/multicast over the wireless meidum. For efficient and robust wireless video broadcast/multicast under fading, this thesis presents and examines a novel cross-layer framework that exploits the interplay between applying protections on a successively refinable video source and transmitting through a layered broadcast/multicast channel. The framework is realistically achieved and evaluated by using multiple description coding (MDC) on a scalable video source and using superposition coding (SPC) for layered broadcast/multicast transmissions. An analytical model using the total received/recovered video bitstreams from each coded wireless broadcast/multicast signal is developed, which serves as a metric of video quality for the system analysis and optimization. An efficient methodology has demonstrated that optimal power allocations and modulation selections can be practically determined to improve the broadcast/multicast video quality. From the information-theoretical perspective, a general closed-form formula is derived for the end-to-end distortion analysis of the proposed framework, which is applicable to any (n, k) protection code applied on a successive refinable source with a Gaussian distribution over layered Gaussian broadcast channels. The results reveal the scenarios for the proposed framework to lead to a lower distortion than a legacy system without any protection. By analyzing the characteristics of the closed-form formula, an efficient O(n log n) algorithm is developed to determine optimal k values in the (n, k) protection codes that minimize the distortion under the framework. Finally, a cross-layer design of logical SPC modulation is introduced to achieve layered broadcast/multicast for scalable video. It serves as an alternative for practically implementing the proposed framework of coded wireless video broadcast/multicast, if the hardware-based SPC component is not available in a wireless system. In summary, the thesis presents comprehensive analyses, simulations, and experiments to understand, investigate, and justify the effectiveness of the proposed cross-layer framework of coded wireless video broadcast/multicast. More importantly, this thesis contributes to the advancement in the related fields of communication engineering and information theory by introducing a new design dimension in terms of protection. This is unique when compared to previously-reported layered approaches that are often manipulating conventional parameters alone such as power and modulation scheme. The impact of this dimension was unapparent in the past, but is now proven as an effective means to enable high-quality, efficient, and robust wireless video broadcast/multicast for promising media applications.

Advancements in video coding, compact media display, and communication devices, particularly in emerging broadband wireless access networks, have created many foreseeable and exciting applications of video broadcast/multicast over the wireless meidum. For efficient and robust wireless video broadcast/multicast under fading, this thesis presents and examines a novel cross-layer framework that exploits the interplay between applying protections on a successively refinable video source and transmitting through a layered broadcast/multicast channel. The framework is realistically achieved and evaluated by using multiple description coding (MDC) on a scalable video source and using superposition coding (SPC) for layered broadcast/multicast transmissions. An analytical model using the total received/recovered video bitstreams from each coded wireless broadcast/multicast signal is developed, which serves as a metric of video quality for the system analysis and optimization. An efficient methodology has demonstrated that optimal power allocations and modulation selections can be practically determined to improve the broadcast/multicast video quality. From the information-theoretical perspective, a general closed-form formula is derived for the end-to-end distortion analysis of the proposed framework, which is applicable to any (n, k) protection code applied on a successive refinable source with a Gaussian distribution over layered Gaussian broadcast channels. The results reveal the scenarios for the proposed framework to lead to a lower distortion than a legacy system without any protection. By analyzing the characteristics of the closed-form formula, an efficient O(n log n) algorithm is developed to determine optimal k values in the (n, k) protection codes that minimize the distortion under the framework. Finally, a cross-layer design of logical SPC modulation is introduced to achieve layered broadcast/multicast for scalable video. It serves as an alternative for practically implementing the proposed framework of coded wireless video broadcast/multicast, if the hardware-based SPC component is not available in a wireless system. In summary, the thesis presents comprehensive analyses, simulations, and experiments to understand, investigate, and justify the effectiveness of the proposed cross-layer framework of coded wireless video broadcast/multicast. More importantly, this thesis contributes to the advancement in the related fields of communication engineering and information theory by introducing a new design dimension in terms of protection. This is unique when compared to previously-reported layered approaches that are often manipulating conventional parameters alone such as power and modulation scheme. The impact of this dimension was unapparent in the past, but is now proven as an effective means to enable high-quality, efficient, and robust wireless video broadcast/multicast for promising media applications.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / A conventionally designed radio frequency amplifier operated in its linear region exhibits low DC to RF conversion efficiency. Typically, for a power amplifier designed for digital modulation applications, the amplifier is operated “backed-off” from its P1dB point by a factor of 10 or -10 dB. The typical linear amplifier is biased for either Class A or Class A/B operation depending on the acceptable design trade-offs between efficiency and linearity between these two methods. A novel design approach to increasing the efficiency of a linear RF power amplifier using a modified Odd-Way Doherty technique is presented in this paper. The design was simulated, built and then tested. The design yields improvements in efficiency and linearity.

Les progrès réalisés en systèmes micro-électro-mécaniques couplés avec leur convergence vers les systèmes de communication sans fil, ont permis l'émergence des réseaux de capteurs sans fil (RCSF). Les contraintes de ces réseaux font que tous les efforts soient fournis pour proposer des solutions économes en énergie. Avec les récents développements des technologies CMOS, des capteurs d'images à faible coût ont été développés. En conséquence, un nouveau dérivé des RCSF, qui sont les Réseaux de Capteurs Vidéo Sans Fil (RCVSF), a été proposé. La particularité des données vidéo ainsi que les contraintes inhérentes aux nœuds ont introduit de nouveaux défis. Dans cette thèse, nous proposons deux solutions basées sur l'approche inter-couches pour la livraison de la vidéo sur les RCVSF. La première solution propose un nouveau schéma de compression vidéo adaptatif, efficace en énergie et basé sur la norme de compression vidéo H.264/AVC. Le flux vidéo est ensuite géré par une version améliorée du protocole MMSPEED que nous proposons et notons EQBSA-MMSPEED. Les résultats des simulations montrent que la durée de vie du réseau est étendue de 33%, tout en améliorant la qualité du flux vidéo reçu de 12%. Dans la deuxième solution, nous enrichissons le schéma de compression de modèles mathématiques pour prévoir la consommation d'énergie et la distorsion de l'image lors des phases d'encodage et de transmission. Le flux vidéo est géré par un nouveau protocole de routage efficace en énergie et à fiabilité améliorée noté ERMM. Comparée à une approche basique, cette solution réalise une extension de la durée de vie du réseau de 15%, tout en améliorant la qualité du flux vidéo reçu de 35%. / Thanks to the valuable advances in Micro Electro-Mechanical Systems coupled with their convergence to wireless communication systems, the Wireless Sensor Networks (WSN). In the WSN context, all the efforts are made in order to propose energy-efficient solutions. With the recent developments in CMOS technology, low-cost imaging sensors have been developed. As a result, a new derivative of the WSN, which is the Wireless Video Sensor Network (WVSN), has been proposed. The particularities of the video data as well as the inherent constraints of the nodes have introduced new challenges. In this thesis, we propose two cross-layer based solutions for video delivery over the WVSN. The first solution proposes a new energy efficient and adaptive video compression scheme dedicated to the WVSNs, based on the H.264/AVC video compression standard. The video stream is then handled by an enhanced version of MMSPEED protocol, that we propose and note EQBSA-MMSPEED. Performance evaluation shows that the lifetime of the network is extended by 33%, while improving the video quality of the received stream by 12%. In the second solution, we enrich our compression scheme with mathematical models to predict the energy consumption and the video distortion during the encoding and the transmission phases. The video stream is then handled by a novel energy efficient and improved reliability routing protocol, that we note ERMM. Compared to a basic approach, this solution is extending the network lifetime by 15%, while improving the quality of the received video stream by 35%.