A Study Of Unequal Error Protection Technology In Wireless Video Transmission

As the mainstream standard of video compression application, the variable length coding(VLC)and the predictive coding technology used in H.264/AVC make the compressed video streamsextraordinarily sensitive to transmission errors. Coupled with the time-varying characteristics ofwireless channel, the compressed video streams are affected by many interference, resulting in highbit error rate. Taking the figures of compressed video streams into account, different bit playsdifferent roles during the reconstruction, so we should offer different degree of protection to themaccording to their importance, in order to obtain better image quality. In addition, unequal errorprotection need to adjust dynamically with the compression mechanism and the change oftransmission environment to reduce the waste of wireless resources and the instability of the systemperformance. In this paper, in-depth explorations and researches are made on unequal errorprotection of wireless video transmission, the main contents are as follows:1.Focused on the structure of H.264streams, a simple and effective method for dataprioritization partitioning is proposed, namely data segmentation method based on NAL unit. In thismethod, sequence parameter set(SPS), picture parameter set(PPS) and I frames are divided intoimportant bits, the rest of P frames as unimportant part. The partition type can effectivelydistinguish the importance of video information.2.Combine the stream segmentation strategy based on NAL unit with16-HQAM to realizeunequal error protection transmission. In the hierarchical QAM, important bits are mapped onto themost significant bits(MSBs, namely high two bits), and unimportant bits are mapped onto thecorresponding least significant bits(LSBs, namely low two bits). Simulation results show that thescheme can efficiently improve the quality of recovery video in low bit SNR, up to5dB.3.An adaptive64-HQAM unequal error protection method is proposed by research the effect tothe ratio between important bits and unimportant bits with different coding rate. The segmentationof data use DP(Data Partitioning), after which Partition-A is regarded as significant bits, Partition-Band Partition-C are regarded as non-significant bits. System can adaptively switch modulation modeaccording to the ratio between significant bits and non-significant bits so as not to reduce theprotection of important bits. The experimental results show that this scheme can efficiently improvethe quality of wireless video communication, and the effect of the visual perception as well.