EasiCache:一种基于缓存机制的低开销传感器网络代码更新方法

EasiCache:A Low-Overhead Sensor Network Reprogramming Approach Based on Cache Mechanism

随着应用环境越来越复杂多变,传感器网络需要具备远程代码更新的能力,对节点进行灵活地配置和升级以适应环境变化.然而过高的代码更新开销一直困扰着远程代码更新在传感器网络中的大规模应用.代码更新开销主要包括存储代码引起的重组开销和节点通信产生的传输开销.在工程实践中,作者发现重组开销甚至有可能超过传输开销成为主要的更新开销.为此作者提出了一种基于代码缓存机制的低开销远程代码更新方法——EasiCache.该方法通过代码缓存机制在低功耗RAM上动态保存并执行需要频繁更新的代码,尽量避免对高功耗闪存flash进行读写操作,从而有效降低了重组开销.此外,该方法通过函数级代码差异对比,降低了传输代码量,同时保存了代码缓存机制所需的程序结构信息,进一步降低了重组开销.实验结果验证了该方法在降低代码更新开销方面的有效性.

With applied environment of sensor networks becoming complicated and changeable,the over-air reprogramming is necessary for flexibly configuring and updating sensor nodes.However,too high overhead still restraints the large-scale application of the over-air reprogramming.The over-air reprogramming overhead includes the programming and the transmission overhead.In practice,we find the programming overhead may exceed the transmission overhead and thus provide EasiCache,a novel low-overhead reprogramming approach based on cache mechanism.Using the mechanism,the frequently changed codes are dynamically stored and executed in the low-power RAM instead of the high-power flash,which helping to lower the programming overhead.Additional,the approach uses the different code comparison between functions to reserve the program structure information and reduce the transferred code size.The experiment results demonstrate the EasiCache＇s effectiveness of lowering the over-air reprogramming overhead.