Error-prone Transmission Channels Research Articles

Adaptive error protection coding for wireless transmission of motion JPEG 2000 video

The delivery of video over wireless, error-prone transmission channels requires careful allocation of channel and source code rates, given the available bandwidth. In this paper, we present a theoretical framework to find an optimal joint channel and source code rate allocation, by considering an intra-coded video compression standard such as Motion JPEG 2000 and an error-prone wireless transmission channel. Lagrangian optimization is used to find the optimal code rate allocation, from a PSNR perspective, starting from commonly available source coding outputs, such as intermediate rate-distortion traces. The algorithm is simple and adaptive both on the available bandwidth and on the transmission channel conditions, and it has a low computational complexity. Simulation results, using Reed-Solomon (R-S) coding, show that the achieved performance, in terms of PSNR and MSSIM, is comparable with that of other methods reported in literature. In addition, a simplified and sub-optimal expression for determining the channel code assignment is also provided.

A Local Resource Sharing Platform in Mobile Cloud Computing

Despite the increasing use of mobile computing, exploiting its full potential is difficult due to its inherent characteristics such as error-prone transmission channels, diverse node capabilities, frequent disconnections and mobility. Mobile Cloud Computing (MCC) is a paradigm that is aimed at overcoming previous problems through integrating mobile devices with cloud computing. Mobile devices, in the traditional client-server architecture of MCC, offload their tasks to the cloud to utilize the computation and storage resources of data centers. However, along with the development of hardware and software technologies in mobile devices, researchers have begun to take into consideration local resource sharing among mobile devices themselves. This is defined as the cooperation based architecture of MCC. Analogous to the conventional terminology, the resource platforms that are comprised of surrounding surrogate mobile devices are called local resource clouds. Some researchers have recently verified the feasibility and benefits of this strategy. However, existing work has neglected an important issue with this approach, i.e., how to construct local resource clouds in dynamic mobile wireless networks. This paper presents the concept and design of a local resource cloud that is both energy and time efficient. Along with theoretical models and formal definitions of problems, an efficient heuristic algorithm with low computational complexity is also presented. The results from simulations demonstrate the effectiveness of the proposed models and method.

Perceptually driven video error protection using a distributed source coding approach

In video communication systems, the video signals are typically compressed and sent to the decoder through an error-prone transmission channel that may corrupt the compressed signal, causing the degradation of the final decoded video quality. In this context, it is possible to enhance the error resilience of typical predictive video coding schemes using as inspiration principles and tools from an alternative video coding approach, the so-called Distributed Video Coding (DVC), based on the Distributed Source Coding (DSC) theory. Further improvements in the decoded video quality after error-prone transmission may also be obtained by considering the perceptual relevance of the video content, as distortions occurring in different regions of a picture have a different impact on the user's final experience. In this context, this paper proposes a Perceptually Driven Error Protection (PDEP) video coding solution that enhances the error resilience of a state-of-the-art H.264/AVC predictive video codec using DSC principles and perceptual considerations. To increase the H.264/AVC error resilience performance, the main technical novelties brought by the proposed video coding solution are: (i) design of an improved compressed domain perceptual classification mechanism; (ii) design of an improved transcoding tool for the DSC-based protection mechanism; and (iii) integration of a perceptual classification mechanism in an H.264/AVC compliant codec with a DSC-based error protection mechanism. The performance results obtained show that the proposed PDEP video codec provides a better performing alternative to traditional error protection video coding schemes, notably Forward Error Correction (FEC)-based schemes.

Multiple-layer scalable video coding technology based on MB-level data partition for wireless sensor networking

With the fast development of mobile network and communications, the number of mobile users increased amazingly. However, due to the limited bandwidth and error-prone character of the transmission channel of current wireless network, smooth real-time data transmission for mobile terminals is challenging, especially for the object which has amount of data, such as video signal. In this paper, an efficient multiple-layer scalable video coding (MLSVC) algorithm for wireless communications is proposed to avoid whole MB information loss due to the packet loss of the error-prone transmission channel. Different with the conventional scalable video coding (SVC) method, the proposed method segments the video signal in Macroblock Level (ML) during the encoding period according to the requirement of the bandwidth of the appointed wireless transmission channels to generate multiple sub-bitstreams which could be transmitted from the sender to the destination trough various channels of the wireless network. The simulation results demonstrate that our proposed ML–MLSVC algorithm can achieve excellent performance in terms of encoding processing, bandwidth occupancy, transmission time and video quality. One typical potential application for our work is that it could be employed for video signal transmission through bandwidth-limited wireless transmission channels, such as sensor and wifi network.

Atherosclerotic Plaque Ultrasound Video Encoding, Wireless Transmission, and Quality Assessment Using H.264

We propose a unifying framework for efficient encoding, transmission, and quality assessment of atherosclerotic plaque ultrasound video. The approach is based on a spatially varying encoding scheme, where video-slice quantization parameters are varied as a function of diagnostic significance. Video slices are automatically set based on a segmentation algorithm. They are then encoded using a modified version of H.264/AVC flexible macroblock ordering (FMO) technique that allows variable quality slice encoding and redundant slices (RSs) for resilience over error-prone transmission channels. We evaluate our scheme on a representative collection of ten ultrasound videos of the carotid artery for packet loss rates up to 30%. Extensive simulations incorporating three FMO encoding methods, different quantization parameters, and different packet loss scenarios are investigated. Quality assessment is based on a new clinical rating system that provides independent evaluations of the different parts of the video (subjective). We also use objective video-quality assessment metrics and estimate their correlation to the clinical quality assessment of plaque type. We find that some objective quality assessment measures computed over the plaque video slices gave very good correlations to mean opinion scores (MOSs). Here, MOSs were computed using two medical experts. Experimental results show that the proposed method achieves enhanced performance in noisy environments, while at the same time achieving significant bandwidth demands reductions, providing transmission over 3G (and beyond) wireless networks.

G.718: A new embedded speech and audio coding standard with high resilience to error-prone transmission channels

This article is an overview of the standardization, architecture, and performance of the new ITU-T Recommendation G.718. G.718 is an embedded variable bit rate codec providing a scalable solution for compression of 8 and 16 kHz sampled speech and audio signals at rates between 8 kb/s and 32 kb/s. It comprises five layers where higher-layer bitstreams can be discarded without affecting the lower layersiquest decoding. The codec also has an optional core layer interoperable with ITU-T G.722.2 (3GPP AMR-WB) at 12.65 kb/s. G.718 was designed to provide high speech quality at low bit rates and to be robust to significant rates of frame erasures or packet losses. It is also targeting good quality for generic audio at higher rates.

Extensions of ITU-T recommendation H.324 for error-resilient video transmission

The authors provide an overview of techniques that enable the use of ITU-T recommendation H.324 with error-prone transmission channels. H.324 covers the overall architecture, algorithms, and syntax for low-bit-rate multimedia terminals. This overview focuses on extensions for error-resilient video transmission that are related to the H.263 video codec and H.223 multiplex. The latter is responsible for reliable delivery of data to each terminal component and is therefore of major importance to the overall system. In particular, the discussed approaches to robust video transmission require reliable performance of the multiplex scheme. The considered techniques for video coding are either compatible with the baseline mode of H.263 or part of new extensions recently devised by Study Group 16 as part of the H.263+ effort. This overview includes "error tracking" (Appendix II). "reference picture selection" (Annex N), and "independent segment decoding" (Annex R). Whenever appropriate, the description of those video extensions and multiplex schemes is complemented with simulation results for transmission over Rayleigh fading channels.