Optimized unequal error protection of embedded video bitstream using adaptive-hierarchical QAM

Autor: Ekram Khan, Mohd Ayyub Khan, Athar Ali Moinuddin, Mohammad Ghanbari
Rok vydání: 2015
Předmět:
Zdroj: Multimedia Tools and Applications. 75:15729-15762
ISSN: 1573-7721
1380-7501
DOI: 10.1007/s11042-015-2886-9
Popis: In this paper, a reliable video communication system using adaptive Hierarchical QAM (HQAM) is designed to provide optimized unequal error protection (UEP) to embedded video bitstreams. Based on the relative importance of bits, video bitstream is partitioned into two priorities, namely High Priority (HP) and Low Priority (LP) substreams. Then, the optimal value of modulation (or hierarchical) parameter (ź) of HQAM, which controls the relative error protection of these substreams, is selected from a pre-designed look-up table. The proposed system adapts itself by adapting the optimal ź according to the varying channel condition, without changing the modulation level. This is in contrast to conventional WiMAX and LTE systems, in which dynamic switching among multiple modulations is used to adapt the varying channel conditions. This paper proposes HQAM with adaptive ź as an alternative to the multiple modulation schemes. Moreover, for fixed average transmission power, receiver demodulates symbols without the knowledge of ź. In order to further improve the video quality and to reduce the effects of erroneously received LP bits, the proposed system uses another level of adaptation, in which received LP bits are adaptively considered or discarded, before decoding the video, depending on the channel conditions (or optimized ź). Simulation results show that proposed system can achieve significant improvement in the video quality compared to QAM based EEP scheme and non-adaptive HQAM.
Databáze: OpenAIRE
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