The increasing demand on multimedia communication over wired and wireless networks imposes a continuous pressure on developing more robust coding schemes. Recently, joint source-channel coding with multiple description codes has become an attractive solution to ensure robust communication over noisy channels. In this thesis, we conduct analysis and design of multiple description codes for wired and wireless communication channels. First, a multiple description quantizer (MDQ) design method based on channel optimized quantization is developed. The proposed multiple channel optimized quantizer design scheme does not require index assignment and offers the benefit of resilience to both symbol and erasure errors. Low complexity MDQ is further explored and used to build a multiple description audio coder. Next, the advantages of employing multiple description coding over multiple-input multiple-output wireless channels are investigated. Information theoretical analysis is conducted and practical MDQ codes are designed. Finally, a new E-model based performance measure accounting for both rate-distortion performance and delay impairment is proposed to compare multiple description coding and layered coding for communication over packet networks. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2007-09-28 15:07:27.322

Multiple description coding (MDC) has received a lot of attention recently, and has been studied widely and extended to many demanding applications such as speech and video. MDC is a coding technique that generates correlated descriptions of the source stream for transmitting over a diversity system with several channels. The objective of this diversity system is to overcome channel impairments and provide more reliability. In the context of lossy source coding and quantization, a multiple description quantization system usually consists of multiple channels, side encoders to quantize the source samples and send over different channels, and side and central decoders to reconstruct the source. We propose two multiple description quantization schemes in order to design the codebooks and partitions of side and central quantizers of a multiple description system with two channels. The applied framework originated in the multiple description quantization via Gram-Schmidt orthogonalization approach. The basic idea of our proposed schemes is to minimize a Lagrangian cost function by an iterative technique which jointly designs side codebooks and partitions. Our proposed methods perform very closely to the optimum MD quantizer with considerably less complexity. We also propose a multiple description video coding technique motivated by human visual perception. We employ two simple parameters as a measure of the perceptual tolerance of discrete cosine transform (DCT) blocks against visual distortion. We duplicate the essential information such as motion vectors and some low-frequency DCT coefficients of prediction errors into each description, and split the remaining high-frequency DCT coefficients according to the calculated perceptual tolerance parameter. Our proposed technique has very low complexity and achieves superior performance compared to other similar techniques which do not consider perceptual distortion in the design problem. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-08-19 03:33:10.451

This thesis devises quantization and source-channel coding schemes to increase the error robustness of the newly standardized ITU-T G.711.1 speech coder. The schemes employ Gaussian mixture model (GMM) based multiple description quantizers (MDQ). The thesis reviews the literature focusing on GMM based quantization, MDQ, and GMM-MDQ design methods and bit allocation schemes. GMM-MDQ are then designed for the quantization and coding of the MDCT coefficients in the G.711.1 speech coder. The designs are optimized for and tested over packet erasure channels. Performance of the designs are compared with Mohr's forward error correcting code based multiple description coding (MDC) scheme. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-06-02 16:02:11.727

This thesis addresses the optimal scalar quantizer design for two problems, i.e. the two-stage Wyner-Ziv coding problem and the multiple description coding problem for finite-alphabet sources. The optimization problems are formulated as the minimization of a weighted sum of distortions and rates. The proposed solutions are globally optimal when the cells in each partition are contiguous. The solution algorithms are both based on solving the single-source or the all-pairs minimum-weight path (MWP) problems in certain weighted directed acyclic graphs (WDAG). When the conventional dynamic programming technique is used to solve the underlying MWP problems the time complexity achieved is $O(N^3)$ for both problems, where $N$ is the size of the source alphabet. We first present the optimal design of a two-stage Wyner-Ziv scalar quantizer with forwardly or reversely degraded side information (SI) {for finite-alphabet sources and SI}. We assume that binning is performed optimally and address the design of the quantizer partitions. A solution based on dynamic programming is proposed with $O(N^3)$ time complexity. %The solution relies on finding the single-source or the all-pairs MWP in several one dimensional WDAGs. Further, a so-called {\it partial Monge property} is additionally introduced and a faster solution algorithm exploiting this property is proposed. Experimental results assess the practical performance of the proposed scheme. Then we present the optimal design of an improved modified multiple-description scalar quantizer (MMDSQ). The improvement is achieved by optimizing all the scalar quantizers. %are optimized under the assumption that all the central and side quantizers have contiguous codecells. The optimization is based on solving the single-source MWP problem in a coupled quantizer graph and the all-pairs MWP problem in a WDAG. Another variant design with the same optimization but enhanced with a better decoding process is also presented to decrease the gap to theoretical bounds. Both designs for the second problem have close or even better performances than the literature as shown in experiments. / Thesis / Master of Applied Science (MASc)

This thesis addresses the design of multiple description lattice vector quantizer (MDLVQ) with a general number L of descriptions, L >= 3. In the previous work on MDLVQ with L>= 3, once the central and side lattice codebooks are fixed, the decoding quality is determined for all numbers k of received descriptions. Therefore, it is not possible to achieve tradeoffs between the quality of reconstruction for different values of k, 1<= k <= L-1. In order to overcome the above drawback, we propose two flexible MDLVQ schemes for L >= 3. Our first design employs a different reconstruction method than in prior work and a heuristic index assignment algorithm, which uses L-2 parameters to control the distortions for 2 <= k <= L-1. Experimental results for the cases L=3 and L=4 show that significant tradeoffs are achieved by controlling the parameters mentioned above. Our second design is based on a structured index assignment. We start with the case L=3 and then generalize the index assignment to any L >= 3. The structured index assignment is able to control the tradeoff by adjusting the sizes of some L-1 subsets of side lattice points. Another important contribution of the thesis is the derivation of analytical expressions of the distortions for the structured index assignment, under the high resolution assumption. These expressions show that a wide range of distortion values can be achieved. / Thesis / Master of Applied Science (MASc)

This thesis studies multicasting high bandwidth media traffic in wireless mesh networks (WMNs). Traditional multicast methods use a single multicast tree to reach all destinations, and adapt the multicast rate to the destination with the worst path quality. This approach does not fully utilize the network resources nor distinguish the quality of service (QoS) requirements of different users. It also penalizes the users having better path quality and requiring higher QoS. In multi-hop transmissions, the end-to-end transmission rate is limited by the link with the worst transmission conditions. This makes it difficult to multicast high-bandwidth media traffic with good quality. Using multiple description coding (MDC), the source traffic can be split into multiple sub-streams, referred to as descriptions, each of which requires a much lower bandwidth and can be transmitted along separate paths. In this thesis, we study routing and QoS provisioning jointly for multicasting multiple description (MD) encoded media traffic in WMNs. Routing for the multiple descriptions is jointly studied, while considering the channel quality of different links in the network and QoS at individual destinations. The work in this thesis is divided into two parts. The first part (Chapters 3 and 4) considers balanced descriptions, each of which contributes equally to the quality of the recovered media at a destination, and we study the problem of power efficient multicasting for the MD-encoded media traffic in WMNs. In Chapter 3, single-hop transmissions are considered. That is, the access points (APs) that store the source traffic communicate with the destination nodes directly. We study two problems jointly, description assignments and power allocations. The former is to assign a description for each AP to transmit, and the latter is to allocate the transmission power for the APs. Different power efficiency objectives are considered, subject to satisfying the QoS requirements of the destination nodes. For each objective, an optimization problem is formulated and heuristic solutions are proposed. Chapter 4 extends the work to multi-hop transmissions, where relay stations (RSs) are available to forward the traffic from the APs to the destinations. We consider two different routing structures based on whether an RS is allowed to forward more than one description. The objective is to minimize the total transmission power of the APs and the RSs in the network, subject to the QoS requirements of the destinations. An optimum problem is formulated and then translated to an integer and linear programming problem, and a centralized scheme with much lower complexity is proposed. Following that, a distributed scheme, referred to as minimum weight k-path scheme, is proposed, which builds one multicast tree for each description. By permitting only neighboring nodes to exchange related information, the scheme allows each node to find its best parent node based on the additional transmission power needed to establish the link. The second part (Chapter 5) of the thesis considers unbalanced descriptions. Routing for the multiple descriptions is jointly considered with application layer performance, so that the maximum distortion of recovered media at the destinations is minimized. An optimization problem is first formulated, and a centralized scheme with lower complexity is proposed. The centralized scheme first finds a set of candidate paths for each destination based on a predefined set of criteria, then it iteratively expands the multicast trees by only merging the paths that minimize the maximum distortion for all destinations. A distributed scheme is also proposed by modifying the minimum weight k-path scheme. In the modified scheme, each RS makes a local decision to join different multicast trees based on the expected distortion among its connected downstream nodes. The proposed multicasting schemes require much lower implementation complexity, compared to the optimum solutions. The centralized scheme is more suitable for small size networks, and achieves close-to-optimum performance for a wide range of parameter settings. The distributed scheme only requires neighboring nodes to exchange information, and can be implemented to networks with a relatively large number of APs, RSs, and destination nodes. / Thesis / Doctor of Philosophy (PhD)

In this thesis, a novel Scalable Multiple Description Coding (SMDC) framework is proposed. To address the bandwidth fluctuation, packet loss and heterogeneity problems in the wireless networks and further enhance the error resilience tools in Moving Pictures Experts Group 4 (MPEG-4), the joint design of layered coding (LC) and multiple description coding (MDC) is explored. It leverages a proposed distributed multimedia delivery mobile network (D-MDMN) to provide path diversity to combat streaming video outage due to handoff in Universal Mobile Telecommunications System (UMTS). The corresponding intra-RAN (Radio Access Network) handoff and inter-RAN handoff procedures in D-MDMN are studied in details, which employ the principle of video stream re-establishing to replace the principle of data forwarding in UMTS. Furthermore, a new IP (Internet Protocol) Differentiated Services (DiffServ) video marking algorithm is proposed to support the unequal error protection (UEP) of LC components of SMDC. Performance evaluation is carried through simulation using OPNET Modeler 9. 0. Simulation results show that the proposed handoff procedures in D-MDMN have better performance in terms of handoff latency, end-to-end delay and handoff scalability than that in UMTS. Performance evaluation of our proposed IP DiffServ video marking algorithm is also undertaken, which shows that it is more suitable for video streaming in IP mobile networks compared with the previously proposed DiffServ video marking algorithm (DVMA).

In a wireless fading relay system with multicast/broadcast transmission, one of the most crucial challenges is the optimization of a transmission rate under multiuser channel diversity. Previously reported solutions for mitigating the vicious effect due to multi-user channel diversity have been mainly based on superposition coded multicast, where an optimal power allocation to each layer of modulated signals is determined. Many previous studies investigated a harmonic interplay between the successively re nable (SR) content source and a layered modulation via superposition coding (SPC) over the multicast/broadcast channels. By jointly considering the successive re nement characteristic at the source and the dependency of the layered modulation at the channel, a graceful fexibility can be achieved on a group of users with di erent channel realizations. Here most of the receivers are supposed to obtain the base quality layer information modulated in a lower rate, while the receivers with better channel realizations will obtain more information by re ning the base quality layer information using the enhancement quality layer information. In particular, the optimal power allocation for a SR source over a fading relay channel using broadcast/multicast strategy can be determined such that the minimum distortion of total received information is produced. However, a quality layer of data in a successively refined source may not be decodable if there is any loss of channel codewords, even if the corresponding longterm channel realization is su cient for decoding. To overcome this problem, one of the previous studies introduced a framework of coded video multicast, where multiple description coding (MDC) is applied to an SR content source and is further mapped into a layered modulation via SPC at the channel. Up till now, there has not been a rigorous proof provided on the bene t of manipulating the two coding techniques, (i.e. MDC and SPC), nor has any systematic optimization approach been developed for quantifying the parameter selection. Cooperative relaying in wireless networks has recently received much attention. Because the received signal can be severely degraded due to fading in wireless communications, time, frequency and spatial diversity techniques are introduced to overcome fading. Spatial diversity is typically envisioned as having multiple transmit and/or receive antennas. Cooperation can be used here to provide higher rates and results in a more robust system. Recently proposed cooperation schemes, which take into account the practical constraint that the relay cannot transmit and receive at the same time, include amplify-forward(AF), decode-forward(DF), and compress-forward(CF). In this study, in a fading relay scenario, a proposed framework is investigated to tackle the task of layered power allocation, where an in-depth study is conducted on achieving an optimal power allocation in SPC, such that the information distortion perceived at the users can be minimized. This thesis provides a comprehensive formulation on the information distortion at the receivers and a suite of solution approaches for the developed optimization problem by jointly considering MDC and SPC parameter selection over the fading relay channel.

In this thesis, a novel Scalable Multiple Description Coding (SMDC) framework is proposed. To address the bandwidth fluctuation, packet loss and heterogeneity problems in the wireless networks and further enhance the error resilience tools in Moving Pictures Experts Group 4 (MPEG-4), the joint design of layered coding (LC) and multiple description coding (MDC) is explored. It leverages a proposed distributed multimedia delivery mobile network (D-MDMN) to provide path diversity to combat streaming video outage due to handoff in Universal Mobile Telecommunications System (UMTS). The corresponding intra-RAN (Radio Access Network) handoff and inter-RAN handoff procedures in D-MDMN are studied in details, which employ the principle of video stream re-establishing to replace the principle of data forwarding in UMTS. Furthermore, a new IP (Internet Protocol) Differentiated Services (DiffServ) video marking algorithm is proposed to support the unequal error protection (UEP) of LC components of SMDC. Performance evaluation is carried through simulation using OPNET Modeler 9. 0. Simulation results show that the proposed handoff procedures in D-MDMN have better performance in terms of handoff latency, end-to-end delay and handoff scalability than that in UMTS. Performance evaluation of our proposed IP DiffServ video marking algorithm is also undertaken, which shows that it is more suitable for video streaming in IP mobile networks compared with the previously proposed DiffServ video marking algorithm (DVMA).

In a wireless fading relay system with multicast/broadcast transmission, one of the most crucial challenges is the optimization of a transmission rate under multiuser channel diversity. Previously reported solutions for mitigating the vicious effect due to multi-user channel diversity have been mainly based on superposition coded multicast, where an optimal power allocation to each layer of modulated signals is determined. Many previous studies investigated a harmonic interplay between the successively re nable (SR) content source and a layered modulation via superposition coding (SPC) over the multicast/broadcast channels. By jointly considering the successive re nement characteristic at the source and the dependency of the layered modulation at the channel, a graceful fexibility can be achieved on a group of users with di erent channel realizations. Here most of the receivers are supposed to obtain the base quality layer information modulated in a lower rate, while the receivers with better channel realizations will obtain more information by re ning the base quality layer information using the enhancement quality layer information. In particular, the optimal power allocation for a SR source over a fading relay channel using broadcast/multicast strategy can be determined such that the minimum distortion of total received information is produced. However, a quality layer of data in a successively refined source may not be decodable if there is any loss of channel codewords, even if the corresponding longterm channel realization is su cient for decoding. To overcome this problem, one of the previous studies introduced a framework of coded video multicast, where multiple description coding (MDC) is applied to an SR content source and is further mapped into a layered modulation via SPC at the channel. Up till now, there has not been a rigorous proof provided on the bene t of manipulating the two coding techniques, (i.e. MDC and SPC), nor has any systematic optimization approach been developed for quantifying the parameter selection. Cooperative relaying in wireless networks has recently received much attention. Because the received signal can be severely degraded due to fading in wireless communications, time, frequency and spatial diversity techniques are introduced to overcome fading. Spatial diversity is typically envisioned as having multiple transmit and/or receive antennas. Cooperation can be used here to provide higher rates and results in a more robust system. Recently proposed cooperation schemes, which take into account the practical constraint that the relay cannot transmit and receive at the same time, include amplify-forward(AF), decode-forward(DF), and compress-forward(CF). In this study, in a fading relay scenario, a proposed framework is investigated to tackle the task of layered power allocation, where an in-depth study is conducted on achieving an optimal power allocation in SPC, such that the information distortion perceived at the users can be minimized. This thesis provides a comprehensive formulation on the information distortion at the receivers and a suite of solution approaches for the developed optimization problem by jointly considering MDC and SPC parameter selection over the fading relay channel.