A Comprehensive Analysis of the MAC Unreliability Problem in IEEE 802.15.4 Wireless Sensor Networks
A Comprehensive Analysis of the MAC Unreliability Problem in IEEE 802.15.4 Wireless Sensor Networks
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DOI：
10.1109/tii.2010.2085440
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发表时间：
2011-02-01
影响因子：
12.3
通讯作者：
Di Francesco, Mario
中科院分区：
文献类型：
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作者：
Anastasi, Giuseppe;Conti, Marco;Di Francesco, Mario
无线传感器网络(WSNs)在工业应用的无线技术领域代表着一个非常有前途的解决方案。然而，为了在工业环境中可信地部署无线传感器网络，需要满足四个主要特性，即能量效率、可扩展性、可靠性和及时性。在本文中，我们关注IEEE 802.15.4无线传感器网络，并指出它们可能会遭受严重的不可靠性问题。每当为了能量效率而启用电源管理机制并且导致非常低的分组递送率时，也在网络中的传感器节点的数量非常低(例如，5)时，就会出现该问题。我们在一个实际的无线传感器网络上进行了广泛的分析，基于仿真和实验来研究这个问题的根本原因，我们发现它是由用于信道接入的基于竞争的媒体访问控制(MAC)协议及其默认参数值引起的。我们还发现，在设置更合适的MAC参数的情况下，至少在本文所考虑的场景中，可以缓解问题并实现高达100%的投递率。然而，这种通信可靠性的改善是以增加延迟为代价的，这对于具有严格的定时要求的工业应用来说可能是不可接受的。此外，在某些情况下，这只能通过选择标准正式不允许的MAC参数值来实现。
Wireless Sensor Networks (WSNs) represent a very promising solution in the field of wireless technologies for industrial applications. However, for a credible deployment of WSNs in an industrial environment, four main properties need to be fulfilled, i.e., energy efficiency, scalability, reliability, and timeliness. In this paper, we focus on IEEE 802.15.4 WSNs and show that they can suffer from a serious unreliability problem. This problem arises whenever the power management mechanism is enabled for energy efficiency, and results in a very low packet delivery ratio, also when the number of sensor nodes in the network is very low (e.g., 5). We carried out an extensive analysis-based on both simulation and experiments on a real WSN-to investigate the fundamental reasons of this problem, and we found that it is caused by the contention-based Medium Access Control (MAC) protocol used for channel access and its default parameter values. We also found that, with a more appropriate MAC parameters setting, it is possible to mitigate the problem and achieve a delivery ratio up to 100%, at least in the scenarios considered in this paper. However, this improvement in communication reliability is achieved at the cost of an increased latency, which may not be acceptable for industrial applications with stringent timing requirements. In addition, in some cases this is possible only by choosing MAC parameter values formally not allowed by the standard.