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Design, analysis and applications of robust and efficient transmission schemes for multimedia streaming in wireless networks

Final Report Summary - MMSTREAM (Design, analysis and applications of robust and efficient transmission schemes for multimedia streaming in wireless networks)

Communicating multimedia content such as high-quality images, audio or video streams became a part of everyday life both for the purpose of business and entertainment. However, due to considerable bandwidth consumption and strict quality of service (QoS) requirements, today’s multimedia communications usually take place between stationary users such as desktop/laptop PC’s connected to high-speed wired/wireless Local Area Network (LAN) connections. On the other hand, as user mobility and need for multimedia content available anytime and anywhere increases, multimedia applications such as video streaming, mobile TV, video-conferencing, multimedia peer-to-peer (P2P) networking, social networking with multimedia content, interactive gaming, etc., are becoming a major bandwidth consumer on small, handheld, mobile devices and are indicated in many recent studies as a major driving factor for the next generation mobile broadband technologies such as Mobile WiMax and 3GPP LTE-Advanced that aim to provide sufficient data rates for comfortable high-quality mobile multimedia services.
Although wireless communication standards that support mobile multimedia applications have been successfully launched, research efforts are focused on improving their performance, expanding possibilities and services, addressing clients’ heterogeneity and reducing power requirements. There are number of challenges to ensure reliable high-quality, real-time, lowpower communication services in severe error-prone wireless environment. Firstly, to receive multimedia at high quality, high bandwidth is necessary, which is an expensive resource. Secondly, transmission rates are limited by channel noise, interference, fading, multipath, path loss and shadowing on wireless links, calling for high source compression efficiency and strong channel error protection. Thirdly, end user devices have different capabilities and QoS requirements in terms of bandwidth and screen resolution, which calls for scalable video compression schemes simultaneously adaptable to different users. Finally, low-complexity and power-efficient schemes that operate in real time are required for mobile receivers with limited battery life.
The research on Marie Curie FP7-PEOPLE-IEF MMSTREAM addresses one of the hottest topics in today’s communications: how to robustly and efficiently transmit scalable multimedia data over the existing wireless infrastructure to handheld devices of mobile users. The project started in June 2009 and, lasting for 18 months, was finished in December 2010. The goal of the project was to address the problem of efficient and robust application layer forward error correcting (ALFEC) code design for real-time scalable image/video streaming to handheld devices with varying capabilities and transmission channels with varying severity (e.g. wireless channels in urban/rural settings). The project intended to deeply investigate the design of the state-of-the-art channel coding schemes based on Low Density Parity Check (LDPC) and Digital Fountain (DF) codes, jointly optimized with the scalable image/video sources, with the aim of providing increased end-user Quality of Service (QoS) guarantees for the receivers of low capabilities and/or affected by severe channel conditions, and at the same time providing users with higher capabilities and/or better channel conditions with progressively higher QoS guarantees.
Among the project results, numerous benefits of novel Unequal Error Protection (UEP) DF codes called Expanding Window Fountain (EWF) codes over the existing FEC solutions for multimedia streaming are demonstrated. The simplicity, design flexibility and UEP performance make EWF codes ideally suited for scalable multimedia streaming, i.e. EWF codes offer a number of design parameters to be “tuned” at the server side to meet the different reception conditions of heterogeneous receivers. Apart from optimizing EWF code parameters for increased errorprotection performance of different data importance classes, EWF codes may be optimized with respect to the end-to-end distortion performance of multimedia transmission for different scalable multimedia sources. Furthermore, EWF code parameters may be jointly optimized through the cross-layer optimization techniques with the error-protection mechanisms at lower layers, thereby providing overall optimal error-protection for multimedia services. The work on EWF codes served as an inspiration and is extended towards the end of the project to UEP Network Coding (NC) design.

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