针对基于ARQ机制下的低延时无线视频传输，提出了一种有效的信道信源联合码率控制方案。该方案首先利用Markov模型作为无线信道模型来预测估计信道的状态和带宽，并以基于Cauchy分布的率失真模型作为信源模型；然后在帧层设计了一种基于PID控制器的缓存控制算法，即根据预测信道带宽和缓存器状态来分配每帧目标比特数，以提高缓存的控制能力；对于宏块层则在监控缓存器状态的同时，利用基于Cauchy分布的率失真模型，最后通过Lagrange方法来优化分配目标比特数。实验结果证明，该算法不仅能显著提高平均峰值信噪比，并能大幅减少跳帧数目。

In this paper, we proposed an efficient joint source channel rate control algorithm for real time wireless video transmission which use automatic repeat request scheme to retransmission the error packet. The two state Markov model was used to simulate the wireless channel, and the Cauchy distribution based rate and distortion model were used as the source model. In the new scheme, at frame level, a PID controller based buffer control algorithm was developed to improve the buffer control ability which allocated frame target bit based on the channel bandwidth and buffer status; at macroblock level, the frame bit budget was distributed among macroblocks using the new rate distortion model and Lagrange optimization method. Experimental results show that, the proposed algorithm can improve the average PSNR and decrease the number of skipped frames significantly.