用于视频传输的自适应分级正交幅度调制不等保护方法

Unequal Error Protection Method for Video Transmission Using Adaptive Hierarchical Quadrature Amplitude Modulation

针对已有用于无线视频传输不等保护的分级正交幅度调制(HQAM)不能适应无线信道时变特性和频率选择性的问题,提出一种自适应HQAM不等保护方法(A-HQAM).首先将视频码流按其对恢复视频质量的重要性划分出不同的优先级,然后根据优先级不同数据允许的误码率上限和子载波信道质量,自适应确定对应的HQAM调制参数,最后将视频数据调制到各子载波上实现不等保护传输.与已有同类方法相比,A-HQAM方法可减小无线信道时变特性和频率选择性的影响,改善恢复视频质量.仿真结果表明,相比基于HQAM的不等保护方法,A-HQAM方法可使恢复视频质量平均提高1dB.

An unequal error protection （UEP） method for video transmission using adaptive hierarchical quadrature amplitude modulation （A-HQAM） is proposed to reduce the impact of frequency-selective fading and the time-varying nature of wireless channels. Firstly, the video streams are divided into sub-streams with unequal priorities. Then, the HQAM modulation parameters of each sub-carrier are adaptively determined based on the channel quality of each subcarrier and the upper limit of the bit error rate of the sub-streams with unequal priorities. Finally, UEP is implemented via modulating video streams onto sub-carriers. Simulation results show that the proposed A-HQAM method reduces the impact of frequency-selective fading and the time-varying nature of the wireless channels, and improves the quality of the reconstructed video by an average of 1 dB compared with HQAM-based methods.