Abstract: According to the requirements and features of data transmission in a classroom system with writing teaching equipment for terminal,across analyzing the limitations of other protocols under this situation,an embedded LAN protocol is proposed based on Ethernet,which is suitable for the classroom system CSELP. Both the real-time performance and transmission efficiency are improved. Data frame expansion of 8 Byte achieves recognition,retransmission,flow control and other functions to provide connection-oriented reliable transmission service,and the data processing and sates method are simplified. The size of available bandwidth with improved bandwidth estimate algorithm is estimated and the congestion window by the prediction window size change in congestion avoidance is adjusted. The new design retransmission queue is used to implement the package-based ACK mechanism. Example application result shows that the protocol can satisfy the application requirements of the writing teaching classroom system,and can spread to other nonwriting teaching classroom system.

Key words: text writing teaching device, classroom system, embedded, Ethernet, CSELP protocol, data transmission

摘要： 针对以文字书写教学装置为终端的教室系统的数据传输要求和特性,分析已有协议处于该环境下所面临的局限性,提出一种适合该类教室系统的嵌入式局域网协议CSELP。在以太网帧的基础上扩展8 个字节实现确认、超时重传、流量控制等功能,提供面向连接的可靠传输服务,简化数据处理和状态机制;采用改进的带宽预估算法估计可用带宽大小,在拥塞避免阶段根据预测的窗口大小变化调整拥塞窗口;设计重传队列实现面向组的确认机制,从而提高系统的实时性和传输效率。实验结果表明,该协议能满足文字书写教学教室系统的应用需求,并且可推广到非文字书写教学的教室系统。

关键词: 文字书写教学装置, 教室系统, 嵌入式, 以太网, CSELP 协议, 数据传输

CLC Number: 

• TP393