【作者】 刘锐；

【导师】 马鸿飞； 谢延廷；

【作者基本信息】 西安电子科技大学 ， 电子与通信工程， 2009， 硕士

【摘要】 随着移动和IP网络的发展,也带来了高品质移动音频的巨大需求,但由于网络拥塞,信道干扰和噪音等原因,实时音频通信不得不面对数据包丢失的问题,这严重影响了移动音频的质量。因此,能够提高丢包情况下移动音频质量的抗丢包技术变得日益重要。回声状态网络(ESN)的预测能力可以用以提高移动音频质量。然而,ESN方法中存在输出反馈形成的闭合环路,可能导致ESN丧失渐进稳定性。本文提出了一种利用遗传算法(GA)改进回声状态网络(ESN)稳定性的方法,称为遗传算法回声状态网络(GA-ESN)。本方法采用相空间重构的方法对音频序列进行处理,再将音频送入GA-ESN进行预测,使GA-ESN获得更多的音频序列的信息,提高预测精度。这形成了一种结合混沌时间序列相空间重构方法的GA-ESN直接预测方法,在此基础上本文提出了基于GA-ESN的移动音频抗丢包算法。本文进一步设计了一种基于GA-ESN的移动音频抗丢包算法框架,并在此框架下进行了音频信号的预测,即在25%的丢包环境下设计了一组实验,并用PEAQ和MOS的标准进行了客观和主观评价。实验结果表明,其效果优于工程中用的“错帧填零”方法。更多还原

【Abstract】 With the development of mobile and IP networks, high-quality mobile audio is in great need. Due to the network congestion, channel interference and noise, real-time audio communications have to face the packet-loss issues which seriously affect the the quality of mobile audio. Therefore anti packet loss techniques become increasingly important to improve the quality of mobile audio in the packet-loss situations.The echo state network (ESN) with the predictive capabilities can be used to improve the quality of mobile audio. However, the closed loop with feedback introduced in the ESN may lead to the loss of asymptotic stability. A genetic algorithm (GA) to improve the stability of ESN, called as genetic algorithm for echo state network (GA-ESN), is presented in the thesis. This algorithm reconstructs the audio sequence in the phase space based on the chaotic characteristics of the audio sequece, and predicts the sequence with the GA-ESN. As a result, an anti-packet-loss algorithm for mobile audio application based on the GA-ESN is designed and introduced.A GA-ESN-based anti-packet loss algorithm for mobile audio framework is designed. Under this framework, some audio signal prediction experiments have been conducted under the 25% packet loss rate environment, the PEAQ and MOS are used to evaluate the results. The experiments show that the proposed algorithm is better than the method of "lost frame zero filling".更多还原