面向异步通信机制的无线传感器网络及其MAC协议研究

摘要

Underlying communication of wireless sensor networks is mainly depending on coordinated sleep/wakeup mechanisms, and is still basing the link layer protocols upon the traditional 802. 11. For wireless sensor networks usually having high node density and large scale, 802. 11 protocol is prone to be not efficient in energy consumption, network throughput etc. Basing on the dynamic links in a large portion of monitoring applications of wireless sensor networks, this paper proposes a kind of weak connection-oriented asynchronous communication mechanism (ACM). Differential from traditional RTS/CTS handshaking mechanism, ACM allows transmitter directly write the data into the low power asynchronous module on receiver while it is sleep. In this way, each node can schedule its own transmission without demanding network synchronization. The result is a store-wakeup-forward, asynchronous communication mode in the network. This paper describes the key factors of ACM and proposes two kinds of MAC protocols for differ-ent applications. Moreover, the diffusion approximation based open queuing model is established to analyze the performance of ACM, proving the throughput of ACM is O(W/(n/ogn)＾0. 5). Analytical and experimental results show that, compared to synchronous communication mechanism, ACM is able to prolong network lifetime and improve the throughput.%无线传感器网络的底层通信主要依赖于节点间的协同睡眠/唤醒机制,且仍然在链路层沿袭或扩展传统802.11协议.对于节点密集、网络规模较大的传感器网络而言,传统802.11协议在网络能耗与吞吐量等方面并不是有效的.基于传感器网络在多数应用场景中的链路动态性,文中提出一种面向弱连接的异步通信机制.有别于传统的RTC/CTS握手机制,它允许发送节点直接向“睡眠”的接收节点上的低功耗异步模块写入数据,因此,无需同步机制,单个节点只需按照自身的时间唤醒并进行数据通信,形成一种缓存-唤醒-转发的异步通信模式.文中首先阐述了异步通信机制的关键设计因素,针对不同的应用背景提出两种新的MAC协议.然后,基于扩散近似理论建立开放式排队网络模型,对异步通信机制的性能进行理论分析,得出其网络吞吐量为O(W).理论分析与实验结果表明,与传统同步通信相比,异步通信能在很大程度上延长了网络的生存周期,提高了网络吞吐量.