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PoCH: automatic HDL code generator tool for Polar channel coding decoders in multimedia communication systems
Polar codes are a class of block codes which are widely used in communication networks. Polar codes have been utilized in the fifth generation of enhanced mobile broadband systems (5G) due to their performance in error correction and also their low instinct complexity in implementation. However when they come in very large blocks, their efficient implementation in reasonable time is challenging. The automatic code generator (ACG) tools are useful and essential in these cases, when the design process should be error prone and time consuming. This paper presents an error prone and fast ACG tool to generate the VHDL description code at gate level for Polar decoders in multimedia communication systems according to user adjusted parameters including code-length, code-rate and quantization width, called PoCH tool. The PoCH constructs the Polar decoder using the design SNR and Bhattacharyya parameters which are set by the user, or are provided by a file consisting of the frozen bits location. The PoCH can generate the Polar decoder for four famous algorithms including SC, SSC, Fast-SSC and Fast-SSC + BiREP algorithms. To validate the performance of the PoCH tool, the block counts is presented for each generated code for various code-length, code-rate and Bhattacharyya parameters. Finally, the time consumed by the tool to generate Polar channel decoders for each algorithm is compared.
Journal Article
Cryptographic and parallel hash function based on cross coupled map lattices suitable for multimedia communication security
Cryptographic hash functions can map data of arbitrary size to data of fixed size (hash values), which can be used in a wide range of multimedia applications for communication security, such as integrity protection, message authentication and digital signature. In this paper, we present a cryptographic and parallel chaotic hash function based on the cross coupled map lattices for multimedia communication security. More specifically, we first utilize the piecewise linear chaotic map with secret keys to generate initial parameter sequence for the cross coupled map lattices and an initial hash value. Then, we extend the original message into a message matrix to enhance the correlation of message characters. Next, we process each of the message blocks in the matrix in parallel as the space domain input of the cross coupled map lattices and the initial parameters as the time domain input to generate intermediate hash values. After all message blocks are processed in parallel, the final h-bit hash value is obtained by logical operations with the initial and intermediate hash values. Finally, we evaluate the performance of the proposed hash function in terms of uniform distribution of hash values, sensitivity of the hash value to subtle changes of the original message, secret keys, and images, confusion and diffusion properties, collision tests, efficiency of computation speed. The cryptanalytic results demonstrate that the proposed hash algorithm has statistical properties with B̄=64.0022\\(\\bar {B} = 64.0022\\) and P = 50.0017%, collision resistance with d = 85.3944, average computation speed of 132.0 Mbps, and better statistical performance compared with existing chaotic hash functions, which are suitable for multimedia communication security.
Journal Article
Designing and evaluating the usability of an API for real-time multimedia services in the Internet
In the last few years, multimedia technologies in general, and Real-Time multimedia Communications (RTC) in particular, are becoming mainstream among WWW and smartphone developers, who have an increasing interest in richer media capabilities for creating their applications. The engineering literature proposing novel algorithms, protocols and architectures for managing and processing multimedia information is currently overwhelming. However, most of these results do not arrive to applications due to the lack of simple and usable APIs. Interestingly, in this context in which APIs are the critical ingredient for reaching wide developer audiences, the scientific literature about multimedia APIs and their usability is scarce. In this paper we try to contribute to fill this gap by proposing the RTC Media API: a novel type of API designed with the aim of making simple for developers the use of latest trends in RTC multimedia including WebRTC, Video Content Analysis or Augmented Reality. We provide a specification of such API and discuss how it satisfies a set of design requirements including programming-language agnosticism, adaptation to cloud environments, support to multisensory multimedia, etc. After that, we describe an implementation of such an API that has been created in the context of the Kurento open source software project, and present a study evaluating the API usability performed in a group of more than 40 professional developers distributed worldwide. In the light of the obtained results, we conclude that the usability of the API is adequate across the main development activities (i.e. API learning, code creation and code maintenance), with an average usability score of 3.39 over 5 in a Likert scale, and that this result is robust with respect to developers’ profiles, cultures, professional experiences and preferred programming languages.
Journal Article
A traffic anomaly detection approach in communication networks for applications of multimedia medical devices
Anomalous or unnormal multimedia medical devices are to yield anomaly network traffic and affect the diagnosis about medical issues. How to find anomaly network traffic is significantly important for normal applications of multimedia medical devices. This paper studies traffic anomaly detection problem in large-scale communication networks with multimedia medical devices. We employ empirical mode decomposition method and wavelet packet transform to propose an accurate detection method to capture it. Firstly, we use the wavelet packet transform to pre-treat network traffic. Network traffic is decomposed into multiple narrowband signals exhibiting more detailed features of network traffic. Secondly, the empirical mode decomposition method is utilized to divide these narrowband signals into the intrinsic mode function at different scales, in time and time-frequency domains. We calculate the spectral kurtosis value of the intrinsic mode function at these different scales to remove false components of the empirical mode decomposition. As a result, we can obtain new time and time-frequency signals which highlight the hidden nature of anomaly network traffic. Thirdly, we perform the reconstruction of empirical mode decompositions and wavelet packet transforms for the above time and time-frequency signals to attain a series of new time signals. Then we can find and diagnose abnormal network traffic. Simulation results show that our method is effective and promising.
Journal Article
Multimedia comprehension
\"Multimedia messages use combinations of texts, pictures, maps, and graphs as tools for communication. This book provides a synthesis of theory and research about how people comprehend multimedia. It adopts the perspectives of cognitive psychology, semiotics, anthropology, linguistics, education, and art. Its central idea is that information displays can be categorized into two different but complementary forms of representations, which service different purposes in human cognition and communication. Specific interaction between these representations enhances comprehension, thinking, and problem solving, as illustrated by numerous examples. Multimedia Comprehension is written for a broad audience with no special prior knowledge. It is of interest to everyone trying to understand how people comprehend multimedia, from scholars and students in psychology, communication, and education, to web- and interface-designers and instructors\"-- Provided by publisher.
BOOK
Dynamic Terrain Data Exchange in a Collaborative Terrain Editor
In a computer supported cooperative work (CSCW), data consistency between collaborating users is a crucial issue. Based on the type of the application, ensuring data consistency can be a lengthy process that takes time and affects the system’s performance. In most 3D application, terrain data are massive due to its size. Exchanging this data may be expensive and may cause significant delay. In a real-time collaborative terrain editor, this issue becomes more significant due to terrain data exchange is consistently occurred between collaborating users. We present a solution to perform a conflict-free dynamic terrain data exchange in a real-time collaborative terrain editor. Our objective is to develop a method that able to ensure data consistency amongst collaborating peers in real-time manner. The main idea of our method is to split the terrain into smaller patches and synchronize the changes efficiently by only exchanging the modified patches. We applied our solution to a collaborative terrain editor application to test its performance in a real-time collaborative editing session. The tests were done in multiple scenarios, using different patch model, brush size (in the terrain editor), and connection setup between server and collaborating clients. The result shows that our protocol is capable to maintain data consistency between collaborating clients in a real-time terrain edition session. The delay is varied and highly depends on the data size and client-server environment setup. The overall test shows that it is possible to perform a collaborative terrain editing with an acceptable response time delay. In this paper, we present our proposed method, the implementation, and the result data from the test.
Journal Article