Many video applications, such as mobile TV, videoconferencing, and on-demand video streaming, have gained increased popularity. However, a key problem of video transmission over the existing wireless networks is the mismatch between the nature of the wireless system conditions and the constant quality requirements, such as bandwidth, and packet loss for video applications. Cross-layer design is a natural approach to deal with the incompatibility problem. This approach aims to efficiently perform cross-layer resource allocation (such as bandwidth and transmission power) by increasing the communication efficiency of multiple network layers. In this dissertation, we consider the problem of scalable video transmission over next-generation multi-antenna multi-carrier wireless systems. We propose different resource allocation optimization strategies between application layer and physical layer of the end-to-end system. The proposed framework is general and flexible. Scalability in the video bitstream is exploited by partitioning and producing multiple layers which cater to wide heterogeneous networks. The scalable extension of H.264/AVC, popularly known as scalable video codec (SVC) that provides a combined temporal, quality and spatial scalability is used in this work for transmission over varied networks. We first develop a low-delay low-complexity method for the estimation of the decoded video distortion at the encoder and propose different error concealment schemes. We consider a bandwidth-constrained video transmission over multiple-input multiple-output (MIMO) system with orthogonal space-time block codes (O-STBC). The O-STBC provides spatial diversity and guarantees independent transmission of different symbols within the block code. The hierarchical nature of SVC and orthogonal structure of O-STBC are exploited to design the cross-layer bandwidth optimization strategy. It involves optimally selecting the application layer and physical parameters based on the estimated distortion. The results exemplify the advantages of keeping various parameters under optimization versus allocating them at a fixed value. We consider the transmission of scalable video over MIMO systems using OFDM technique. We propose another modification to the distortion estimation algorithm based on the importance of temporal and quality scalability. We compare the performance under optimal bandwidth allocation framework. Then, we propose transmission power allocation strategies based on using unequal number of OFDM sub-carriers for different layers of scalable video.

This work addresses the topic of optical networks cross-layer design with a focus on physical-layer-impairment-aware design. Contributors captures both the physical-layer-aware network design as well as the latest advances in service-layer-aware network design. Treatment of topics such as, optical transmissions which are prone to signal impairments, dense packing of wavelengths, dispersion, crosstalk, etc., as well as how to design the network to mitigate such impairments, are all covered.

Mobile data traffic has been exponentially increasing during the past years. With the prevalence of video-enabled mobile devices such as smart phones, more than half of the total mobile data traffics are attributed to mobile video traffics. Since wireless resource is limited and video-related applications are bandwidth-consuming, efficiently transmitting videos over wireless networks while providing higher perceptual qualities at the end users become the everlasting endeavors of the service providers. The rapid increasing demands of wireless video streaming services have boosted the developments of video delivery technologies. In the application (APP) layer, more efficient video source coding technologies are designed so that videos with higher qualities can be delivered with less bandwidth consumptions. Among the existing video coding technologies, the scalable video coding (SVC) provides a capability of adapting to various needs or preferences of end users as well as to varying terminal capabilities or network conditions, which makes it an attractive candidate for wireless video streaming applications. In the medium access control (MAC) layer, resource allocation techniques, including rate adaptations and channel selections, are optimized for better wireless resource usages. In the physical (PHY) layer, advanced data transmission schemes such as multi-input multi-output (MIMO) are developed for higher spectral efficiency. To better utilize the advantages of different technologies in different layers, cross-layer design driven by optimizing the end users’ perceptral quality is highly required. In this dissertation, methods of quality-driven cross-layer design of video transmissions over MIMO systems are discussed. First, a near optimal transmit power allocation scheme for delivering SVC-based videos over MIMO systems is discussed. According to the channel state information (CSI) feedbacks, the power of each transmit antennas is adaptively optimized subject to an overall power limit. Therefore, the SVC bit streams with different priorities are transmitted with unequal error protections (UEPs) so that the quality of experience (QoE) at the end user is maximized. Both transmission errors in the PHY layer and video source coding characteristics in the APP layer are jointly considered in this scheme. A near optimal solution is achieved by decomposing the original optimization problem into several convex optimization sub-problems. Detailed algorithms with different complexities and their corresponding theoretical reasonings are provided. The near optimality of the proposed scheme, in terms of measured utilities, is shown by comparing with the exhaustive searched optimal solutions. Simulations with real H.264 SVC video traces demonstrate the effectiveness of the proposed scheme by comparing with other existing schemes in terms of well-accepted video quality assessment methods, such as the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM) index. Second, a joint rate and power adaptation scheme for SVC-based video transmissions over MIMO systems is discussed. The ultimate goal of this scheme is to maximize the decoding quality at the receiver side. The rate adaptation includes selecting the best modulation and coding schemes (MCSs), set of spatial channels, number of SVC layers (source coding rates) and their corresponding application layer forward error correction (APP-FEC) coding rates. The power adaptation involves the proper allocation of the power to each antenna in the MIMO system. In most of the existing studies, the bit stream of each particular SVC layer is allocated to one spatial channel and the UEP is achieved by transmitting the more important SVC layers through the spatial channels with higher channel gains. However, in the proposed scheme, the bit stream of each particular SVC layer is distributed to multiple spatial channels so that additional diversity gain can be exploited by applying APP-FEC. The UEP can also be achieved with different APP-FEC coding rate on each video layer. Moreover, transmit power allocation is also effectively and jointly determined to improve the system performance. The effectiveness and favorable performance of the proposed scheme are shown by simulations with H.264 SVC traces of high definition (HD) video clips over MIMO systems.

The increasing demand for video services over wireless LANs and mobile broad- band networks and the challenges wireless video transmission is facing, drives the need to improve the support for video services over these networks. The aim of this thesis is to design and quantify the benefits of new methods that optimise end-to-end wireless video delivery via generic cross-layer design. These new ar- chitectures encourage complex interactions between the PRY/MAC layers of the wireless system and the application layer of the video services. Wireless networks are fundamentally error-prone due to the time varying nature of the radio channel while video services are typically intolerant to data loss. To improve data reliab- ility wireless networks offer forward error correction (FEC), such as the recently proposed application layer FEC based on Raptor codes, and ARQ packet retrans- mission at the PRY and MAC layers respectively. The performance of the WiFi ARQ mechanism is studied in terms of packet loss and packet delay, using time-correlated packet errors generated from a time- varying channel model. It is shown that prior simulations assuming uncorrelated errors seriously under predict the packet loss rate and latency resulting from ARQ retransmissions. The work in this thesis then focuses on the transmission of video over a mobile WiMAX network. The ARQ mechanism of mobile WiMAX is studied in terms of packet loss rate and latency. The properties and benefits of Raptor codes are then explored. In particular, interactions between the mobile WiMAX Modulation and Coding Scheme, the Raptor block size and the Raptor code rate are explored (for various Doppler spreads) via Monte Carlo simulation. This thesis proposes a novel cross-layer design with tight coupling between formats and packets across the OSI layers. A new methodology based on "Raptor- aware" link adaptation is proposed to select the optimum pairs of MCS mode and Raptor code rate in order to maximise transmission efficiency while maintaining a required level of PER at the application layer. Simulation results show that the proposed methodology significantly reduces the required radio resources, whilst offering error free communication to the video layer. To achieve these gains it is shown that MAC SDUs with missing ARQ blocks must be delivered to the higher layers. This can be achieved with the introduction of a permeable layer into the standard OSI model. Simulations show that to achieve the same level of video performance a standard mobile WiMAX system (at low mobile speeds) requires 118% more bandwidth at an SNR of 18dB, dropping to 40% at 16dB SNR. The proposed design also offers an SNR gain of 4dB which can extend the range of video services (particularly useful for multicast transmissions).

Multimedia services are the killer applications on next generation convergent networks. Video contents are the most resource consuming part of a multimedia flux. Video transmission, video multicast and video conferencing services are the most popular types of video communication with increasing difficulty levels. Four main parts of the distributed cross-layer scalable multimedia services over next generation convergent networks are considered in this research work, both from the architecture and performance point of views. Firstly, we evaluate the performance of scalable multimedia transmissions over an overlay network. For that, we evaluate the performance of scalable video end-to-end transmissions over EvalSVC. It is capable of evaluating the end-to-end transmission of SVC bit-streams. The output results are both objective and subjective metrics of the video transmission. Through the interfaces with real networks and an overlay simulation platform, the transmission performance of different types of SVC scalability and AVC bit-streams on a bottle-neck and an overlay network will be evaluated. This evaluation is new because it is conducted on the end-to-end transmission of SVC contents and not on the coding performance. Next, we will study the multicast mechanism for multimedia content over an overlay network in the following part of this PhD thesis. Secondly, we tackle the problems of the distributed cross-layer scalable multimedia multicast over the next generation convergent networks. For that, we propose a new application-network cross layer multi-variable cost function for application layer multicast of multimedia delivery over convergent networks. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM's media distribution tree. Mathematical derivation and theoretical analysis have been provided for the newly proposed cost function so that it can be applied in more general cases of different contexts. An evaluation platform of an overlay network built over a convergent underlay network comprised of a simulated Internet topology and a real 4G mobile WiMAX IEEE802.16e wireless network is constructed. If multicast is the one-to-many mechanism to distribute the multimedia content, a deeper study on the many-to-many mechanism will be done in the next part of the thesis through a new architecture for video conferencing services. Thirdly, we study the distributed cross-layer scalable video conferencing services over the overlay network. For that, an enriched human perception-based distributed architecture for scalable video conferencing services is proposed with theoretical models and performance analysis. Rich theoretical models of the three different architectures: the proposed perception-based distributed architecture, the conventional centralized architecture and perception-based centralized architecture have been constructed by using queuing theory to reflect the traffic generated, transmitted and processed at the perception-based distributed leaders, the perception-based centralized top leader, and the centralized server. The performance of these three different architectures has been considered in 4 different aspects. While the distributed architecture is better than the centralized architecture for a scalable multimedia conferencing service, it brings many problems to users who are using a wireless network to participate into the conferencing service. A special solution should be found out for mobile users in the next part of the thesis. Lastly, the distributed cross-layer scalable video conferencing services over the next generation convergent network is enabled. For that, an IMS-based distributed multimedia conferencing services for Next Generation Convergent Networks is proposed. [...].