基于优先级赤字轮询调度的WAIC网络延迟分析

Delay analysis of WAIC network based on priority-deficit round robin scheduling

航空电子机内无线通信(WAIC)在降低飞机重量和节省成本等方面的优势让其在航空电子系统的应用上具有可观的前景。为了研究基于802.11的WAIC网络的传输延迟并保证其可靠性,提出了一种优先级赤字轮询调度(PDRR)的介质访问控制(MAC)协议。首先,通过确定性网络演算方法为MAC层协议的活动建立了到达曲线和服务曲线模型。其次,充分考虑无线通信物理层的特点和所结合信道反转方法,给出了WAIC网络流量调度最坏情况下的端到端延迟的评价方法,可以发现信道反转后稳定的信道容量提供了较为保守的延迟界限。最后,通过案例分析对比了高优先级的WAIC节点与普通优先级节点的延迟界限以及信道反转的影响。结果表明:高优先级节点比普通优先级节点具有更好的实时性,并且可以通过增加平均信噪比来改善传输的延迟界限。

The advantages of Wireless Avionics Intra-Communication(WAIC)in reducing aircraft weight and saving cost make it have considerable prospects in the application of avionics systems.In this paper,a Media Access Control(MAC)protocol based on Priority-Deficit Round Robin(PDRR)scheduling is proposed to study the transmission delay of WAIC network based on 802.11 and guarantee its reliability.First,the arrival curve and service curve model for the MAC layer protocol were established by deterministic network calculus where the characteristics of the wireless communication physical layer and the combined channel inversion method were fully considered.Then,based on the worst-case end-to-end delay evaluation method for WAIC network traffic scheduling,it could be found that the stable channel capacity after channel inversion provides a more conservative delay bound.Finally,the delay bound of high-priority WAIC nodes and normal-priority nodes and the influence of channel inversion were compared through case analysis.The results show that high-priority nodes have better real-time performance than normal-priority nodes and the transmission delay bound can be improved by increasing the average signal-to-noise ratio.