基于Wi-Fi的无线控制网络TDMA协议的设计

为解决多种网络协议共存的混合无线网络环境中，控制信息高速、实时、可靠传输的问题，在IEEE802.11协议MAC层基础上开发了TDMA协议。该协议在充分利用Wi-Fi高传输速率的同时，解决了Wi-Fi退避重传机制导致传输时延不确定的问题，增强系统的实时性。实验结果表明，协议在保证95%以上的传输可靠性的同时，传输速率可达5 Mb/s，相较于典型的基于IEEE 802.15.4协议的工业控制网络有大幅提高。TDMA系统中的短帧中有95.4%、长帧中有89.87%可以在2 ms以内的发送完成，传输时延远低于原有的Wi-Fi标准。此外，系统不改变上层协议栈，保持接口的兼容性，便于控制应用程序的开发。

Design of TDMA protocol in wireless control network

To meet the high-rate, real-time and reliable transmission of control information in hybrid wireless network, TDMA protocol is developed on the MAC layer of IEEE 802.11 protocol. This solution not only exploits the high-rate of Wi-Fi, but also overcomes the transmission delay uncertainty and enhances the real-time of system. The experimental results show that the transmission rate can achieve up to 5 Mb/s with 95% transmission reliability, which improves a lot when compared to the existing wireless industrial control network that is based on IEEE 802.15.4 protocol. Additionally, about 95% of the short frame and 89.87% of the long frame can be delivered to the other side within two milliseconds, which is also far below the Wi-Fi standard. What’s more, the new protocol doesn’t change the upper level protocol interfaces, which contributes?to the development of control applications.