%0 Journal Article
%T LDPC FEC Code Extension for Unequal Error Protection in DVB-T2 System: Design and Evaluation
%A Lukasz Kondrad
%A Imed Bouazizi
%A Moncef Gabbouj
%J International Journal of Digital Multimedia Broadcasting
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/834924
%X The Digital Video Broadcasting organisation has recently introduced the second generation of terrestrial broadcast transmission standards, DVB-T2. The newly introduced tools ensure significant gain in performance of DVB-T2 compared to the first generation variant of the standard. One of these tools is the new physical layer concatenated forward error correction code. The inner among the concatenated codes is the Low-Density Parity Check code. The paper proposes a method to extend this code so varying coding strength inside one physical layer pipe of DVB-T2 is enabled in a backward compatible way. As consequence, unequal error protection transmission scheme at a physical layer of DVB-T2 can be efficiently deployed. The paper provides a step-by-step description of the design procedure of the extension. Moreover, the modification to the processing chain and the framing structure of DVB-T2, that ensures backward compatibility to the legacy system, is provided. The proposed method is evaluated under AWGN channel and TU6 channel. Experiments performed on four different video sequences show significant improvements in quality of experience when the proposed extension is used to achieve UEP transmission. 1. Introduction Unequal error protection (UEP) is a well-known technique in multimedia communication used to selectively enhance robustness of transmitted data. The main idea behind UEP is to assign the amount of the protection data based on the relative importance of the protected data to the overall presentation. Scalable media streams [1, 2] inherently contain data with different levels of importance. Thus, they present an ideal use case for UEP transmission schemes. For example, a base layer data of a H.264/SVC video stream is typically FEC coded at a higher protection level compared to an enhancement layer (EL) data of the same stream. This is due to the fact that an error-free enhancement layer data is of no use to an H.264/SVC decoder, if the corresponding base layer (BL) data was corrupted during transmission. By using a UEP transmission scheme jointly with scalable multimedia encoders, graceful quality degradation can be achieved. Thus, a system that supports UEP transmission schemes allow for flexible quality of service configuration. A user with good reception conditions is able to consume a full quality service, while a user with bad reception conditions is still able to consume the service but at a lower quality (lower frame rate, smaller resolution, or lower fidelity). In a system that does not support UEP transmission schemes only one level of
%U http://www.hindawi.com/journals/ijdmb/2012/834924/