Analog-to-digital (A/D) converters are key components in digital signal processing (DSP) systems and are therefore receiving much attention as DSP becomes increasingly prevalent in telephony, audio, video, consumer products, etc. The varying demands on conversion rate, resolution and other characteristics have inspired a large number of competing A/D conversion techniques. Sigma Delta Modulators: Nonlinear Decoding Algorithms and Stability Analysis is concerned with the particular class of A/D techniques called oversampled noise-shaping (ONS) that has recently come into prominence for a number of applications. The popularity of ONS converters is due to their ease of implementation and robustness to circuit imperfectors. An ONS converter consists of an encoder that generates a high-rate, low-resolution digital signal, and a decoder that produces a low-rate, high-resolution digital approximation to the analog encoder input. The conventional decoding approach is based on linear filtering. Sigma Delta Modulators presents the optimal design of an ONS decoder for a given encoder. It is shown that nonlinear decoding can achieve gains in signaling ratio and the encoder architecture. The book then addresses the instability problem that plagues higher-order ONS encoders. A new stability concept is introduced that is well-suited to ONS encoders, and it is applied to the double-loop encoder as well as to the class of interpolative encoders. It is shown that there exists a trade-off between stability and SNR performance. Based on the results, explicit design examples are presented. Sigma Delta Modulators: Nonlinear Decoding Algorithms and Stability Analysis is a valuable reference source for researchers and engineers in industry and academia working on or interested in design and analysis of A/D converters, particularly to those working in quantization theory and signal reconstruction, and can serve as a text for advanced courses on the subjects treated.

Analog-to-digital (A/D) converters are key components in digital signal processing (DSP) systems and are therefore receiving much attention as DSP becomes increasingly prevalent in telephony, audio, video, consumer products, etc. The varying demands on conversion rate, resolution and other characteristics have inspired a large number of competing A/D conversion techniques. Sigma Delta Modulators: Nonlinear Decoding Algorithms and Stability Analysis is concerned with the particular class of A/D techniques called oversampled noise-shaping (ONS) that has recently come into prominence for a number of applications. The popularity of ONS converters is due to their ease of implementation and robustness to circuit imperfectors. An ONS converter consists of an encoder that generates a high-rate, low-resolution digital signal, and a decoder that produces a low-rate, high-resolution digital approximation to the analog encoder input. The conventional decoding approach is based on linear filtering. Sigma Delta Modulators presents the optimal design of an ONS decoder for a given encoder. It is shown that nonlinear decoding can achieve gains in signaling ratio and the encoder architecture. The book then addresses the instability problem that plagues higher-order ONS encoders. A new stability concept is introduced that is well-suited to ONS encoders, and it is applied to the double-loop encoder as well as to the class of interpolative encoders. It is shown that there exists a trade-off between stability and SNR performance. Based on the results, explicit design examples are presented. Sigma Delta Modulators: Nonlinear Decoding Algorithms and Stability Analysis is a valuable reference source for researchers and engineers in industry and academia working on or interested in design and analysis of A/D converters, particularly to those working in quantization theory and signal reconstruction, and can serve as a text for advanced courses on the subjects treated.

In this work, we introduce new path diversity schemes in order to provide robustness for both unicast and multicast video communication applications over wireless ad hoc networks. We first propose a general architecture for multipath video streaming over wireless ad hoc networks. Then for the unicast case, we propose multipath streaming with two node-disjoint paths, which have minimum concurrent Packet Drop Probability (PDP) among all path pairs. This approach minimizes the probability of concurrent loss of all the descriptions, thus optimizing the worst case Multiple Description Coding (MDC) video quality over all times. Based on our path selection model, we propose a heuristic PDP aware multipath routing protocol. For the multicast case, we propose multiple tree video multicast with MDC. Specifically, we propose two distributed protocols, Serial Multiple Disjoint Tree Multicast Routing (Serial MDTMR) and Parallel Multiple Nearly-disjoint Trees Multicast Routing (Parallel MNTMR). We show video quality of proposed protocols are significantly higher than that of other protocols, through extensive NS simulations and actual experiments.

Widely accepted flow control methods in wireline networks, such as TCP for data and TCP Friendly Rate Control (TFRC) for multimedia, assume that packet loss is primarily due to congestion. As such, they fail to apply to wireless networks, in which the bulk of packet loss is due to errors at the physical layer. This often results in serious wireless bandwidth underutilization. In this work, we propose the use of multiple connections within the application layer as a way to improve the throughput and to reduce underutilization in wireless networks. It differs from existing work as follows. First, it is theoretically guaranteed to be optimal, stable and scalable. Second, it end-to-end and requires modifications to neither infrastructure nor transport protocol stack, making it easy to deploy in practice. This work implicitly provides a general framework for flow control. In this framework, it is sufficient to control users' rates and their number of connections independently in two separate timescales, in order to guarantee convergence to a desired equilibrium of the network. This two timescale approach allows modification of the control law in one timescale without affecting the one in the other timescale, or the system's convergence.