Abstract: Problems are always existing when using UDP to implement image transmission in the Internet. The paper analyses the advantages and disadvantages of the existing UDP_based data transfer protocols. On the basis of this, an improved dual congestion control mechanism is proposed. It adds a passive congestion control manner based on the feedback on the sender and an active congestion avoid manner on the receiver. After that the network performance is greatly improved. In order to reduce packet loss rate further, the paper gives a method to process the buffer. The experiment results show that reliability and efficiency have been improved a lot while using the improved congestion control mechanism. The reliability is improved better by adding the method of processing the buffer.

Key words: image transmission, User Datagram Protocol（UDP）, congestion control, buffer management, video surveillance

摘要： 针对直接使用UDP传输视频图像时的诸多问题，分析现有的基于UDP的数据传输协议的优缺点，在此基础上，提出一种改进的双重拥塞控制机制：在发送端添加基于反馈信息的被动拥塞控制算法，在接收端添加主动拥塞避免算法，有效地提高了传输效率。为进一步降低丢包率，提出缓冲区管理策略。实验结果表明，改进后的拥塞控制机制有效提高了数据传输的效率和可靠性。使用缓冲区管理策略后，可靠性还有待进一步提高。

关键词: 图像传输, 用户数据包协议（UDP）, 拥塞控制, 缓冲区管理, 视频监控