Xia Feng, Ma Longhua, Peng Chen, Sun Youxian, Dong Jinxiang
College of Computer Science and Technology, Zhejiang University, Hangzhou 310027, China.
Faculty of Information Technology, Queensland University of Technology, Brisbane QLD 4001, Australia.
Sensors (Basel). 2008 Jul 15;8(7):4265-4281. doi: 10.3390/s8074265.
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting crosslayer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An eventdriven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN.
在网络控制系统中存在使用无线技术的趋势。然而，无线信道的不利特性使得在无线环境中设计和实现控制系统变得困难。为了解决基于无线局域网（WLAN）的无线控制系统中可用通信资源的不确定性问题，开发了一种跨层自适应反馈调度（CLAFS）方案，该方案利用了控制与无线通信的协同设计。通过利用跨层设计，CLAFS根据来自物理层的截止期限错过率和传输速率信息，在应用层调整控制系统的采样周期。在反馈调度框架内，通过控制截止期限错过率来最大化控制性能。反馈调度器的关键设计参数会根据信道条件的动态变化进行调整。还开发了一种用于反馈调度器的事件驱动调用机制。仿真结果表明，所提出的方法在处理信道容量变化和噪声干扰方面是有效的，从而为基于WLAN的控制提供了一种使能技术。
