algorithmics and modular computations, Theory of Codes and Cryptography (3).From an analytical 1. RE Blahut. Theory and practice of error control codes. eecs.uottawa.ca/∼yongacog/courses/coding/ (3) R.E. Blahut,Theory and Practice of Error Control Codes, Addison Wesley, 1983. QA 268. Cached. Download as a PDF 457, Theory and Practice of Error Control CodesBlahut 1984 (Show Context). Citation Context..ontinued fractions.

Theory and practice of error control codes

The transmission of JPEG2000 images over wireless channels is examined using reorganization of the compressed images into error-resilient, product-coded streams. The product-code consists of Turbo-codes and Reed-Solomon codes which are optimized using an iterative process. The generation of the stream to be transmitted is performed directly using compressed JPEG2000 streams. The resulting scheme is tested for the transmission of compressed JPEG2000 images over wireless channels and is shown to outperform other algorithms which were recently proposed for the wireless transmission of images.

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Optimized transmission of JPEG2000 streams over wireless channels

The use of scalable video with layered multicast has been shown to be an effective method to achieve rate control in heterogeneous networks. We propose the use of layered forward error correction (FEC) as an error-control mechanism in a layered multicast framework. By organizing FEC into multiple layers, receivers can obtain different levels of protection commensurate with their respective channel conditions. Efficient network utilization is achieved as FEC streams are multicast, and only to receivers that need them. Furthermore, FEC is used without overall rate expansion by selectively dropping data layers to make room for FEC layers. Effects of bursty losses are amortized by staggering the FEC streams in time, giving rise to a tradeoff between delay and quality. For rate control at the receivers, we propose an equation-based approach that computes network usage as a function of measured network characteristics. We show that equation-based rate control achieves more fair bandwidth sharing amongst competing sessions as compared to existing multicast rate control schemes such as RLM and RLC. Fairness is achieved since competing sessions sharing a path will measure similar network characteristics. Simulations and actual MBONE experiments are performed using error-resilient, scalable video compression. We find that video quality is significantly improved at the same communication rate when layered FEC is used.

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Video multicast using layered FEC and scalable compression

Providing end-to-end quality of service (QoS) support is essential for video delivery over the next-generation wireless Internet. We address several key elements in the end-to-end QoS support, including scalable video representation, network-aware end system, and network QoS provisioning. There are generally two approaches in QoS support: the network-centric and the end-system centric solutions. The fundamental problem in a network-centric solution is how to map QoS criterion at different layers respectively, and optimize total quality across these layers. We first present the general framework of a cross-layer network-centric solution, and then describe the recent advances in network modeling, QoS mapping, and QoS adaptation. The key targets in end-system centric approach are network adaptation and media adaptation. We present a general framework of the end-system centric solution and investigate the recent developments. Specifically, for network adaptation, we review the available bandwidth estimation and efficient video transport protocol; for media adaptation , we describe the advances in error control, power control, and corresponding bit allocation. Finally, we highlight several advanced research directions.

End-to-End QoS for Video Delivery Over Wireless Internet

A multiple protection group (MPG) erasure-resilient coding method for constructing MPG codes for encoding and decoding data. The MPG codes constructed herein protect data chunks of data in multiple protection groups and subgroups. In general, the MPG erasure-resilient codes are constructed by locating data chunks into multiple protection groups and assigning at least one parity chunk to each protection group. Basic MPG codes are constructed from existing Maximum Distance Separable (MDS) codes by splitting at least some of the parity chunks into local parities for each of the multiple protection groups and projecting local parities onto each of the groups. Generalized MPG codes have a Maximally Recoverable property that can be used to determine whether an erasure pattern is recoverable or unrecoverable. Generalized MPG codes can recover any erasure pattern that is recoverable.

Erasure-resilient codes having multiple protection groups

A general model for the transmission of layered video is introduced. The effect of packet dropping in different layers on the reconstruction of pictures is analysed. The application of unequal packet loss protection (UPLP) for layered video is proposed and the performance is investigated. An algorithm for the design of the UPLP parameters is described. The numerical analysis shows that the unequal packet loss protection can significantly improve the communication quality, in the sense of packet loss rate on reconstructing pictures, without any additional complexity in the network infrastructure. It is also shown that application of UPLP can achieve a more efficient bandwidth utilization than the application of ARQ protocols. This technique is suitable for multimedia multicasting in heterogeneous networks, as well as for digital video broadcasting systems which support a variety of receivers with different resolutions and signal processing powers.

Unequal packet loss protection for layered video transmission

Techniques using Reed-Solomon (RS) codes to recover lost packets in digital video/audio broadcasting and packet switched network communications are reviewed. Usually, different RS codes and their corresponding encoders/decoders are designed and utilized to meet different requirements for different systems and applications. We incorporate these techniques into a variable RS code and present encoding and decoding algorithms suitable for the variable RS code. A mother RS code can be used to produce a variety of RS codes and the same encoder/decoder can be used for all the derivative codes, with adding/detecting zeros, removing some parity symbols and adding erasures. A VLSI implementation for erasure decoding of the variable RS code is described and the achievable performance is quantitatively analyzed. A typical example shows that the signal processing speed is up to 2.5 Gbits/second and the processing delay is less than one millisecond, when integrating the decoder on a single chip. Therefore, the proposed algorithm and the encoder/decoder can universally be utilized for different applications with various requirements, such as transmission data rate, packet length, packet loss protection capacity, as well as layered protection and adaptive redundancy protection in DVB/DAB, Internet and mobile Internet communications.

Variable shortened-and-punctured Reed-Solomon codes for packet loss protection

A method of reducing noise in a video signal which includes a plurality of video frames being composed of a plurality of pixels, the method comprising the steps of: comparing video information contained in a current video frame and a plurality of temporally adjacent video frames; selecting from the current video frame and the adjacent video frames the video information that according to a predetermined condition is likely to be correct for the current video frame; and finally assigning the selected video information to the current video frame to thereby produce a video frame wherein noise has been reduced.

Method and device for noise reduction

To efficiently combat the signal loss of MPEG-2 transmission over unreliable networks, priority encoding transmission, unequal packet loss protection and priority dropping techniques have been studied in many papers. Those studies are based on the qualitative analysis of different importance of signals, without quantitative investigation of signal loss effect on video quality. In this paper, MPEG-2 packet loss effect on video quality is quantitatively investigated, a temporal layered signal model is described and evaluated, a quality measure for reconstructed pictures called macroblock impairment ratio is suggested and defined. The investigation and the model are specified for MPEG-2, but the principles and the methods are suitable for any layered video. These are useful for the development of efficient schemes and protocols for packet video transmission over unreliable networks.

Youshi Xu

Papers

Unequal packet loss protection for layered video transmission

Variable shortened-and-punctured Reed-Solomon codes for packet loss protection

Method and device for noise reduction

Numerical modeling of transmission errors and video quality of MPEG-2

Design of Real-Time Signal Processing ASIC for Noise Reduction In Moving Video Images