异构无线传感器网络中一种可扩展的代码分发技术

代码分发一直是无线传感器网络研究的热点问题.目前的研究工作主要集中在同构场景下的代码分发,广播是这些研究工作中最常用的手段.而对于异构场景下的代码分发问题,研究工作则相对较少,传统的基于广播的方法很难直接适用.文中针对异构网络下的代码分发问题,把该问题归约为最小非叶节点MNN(minimum nonleaf nodes)Steiner树问题,并设计了一种基于多播的代码分发协议HSR(heterogeneous sensor networks scalable reprogramming protocol).该协议利用组件化的思想,为不同类型节点(或代码模块)建立了多棵最优代码分发多播树.并证明了在解决MNN问题时,HSR达到了理论最优近似率ln|R|(R为目标节点数),有效的降低了异构网络下代码分发过程中的通信开销和能耗.在此基础上,文中还设计了两种压缩编码机制:特殊路由日志机制SRL(special routinglog)和跳步受限的局部广播机制HLB(hops-restricted local broadcast),使得多播树的信息可以被无损压缩,增强了HSR协议的可扩展性.在实时性方面,提出了基于多播树的3阶段流水线调度方法,有效缓解了隐藏终端和干扰问题.仿真结果证明了协议的正确性和有效性.

A scalable code dissemination protocol in heterogeneous wireless sensor networks

Code dissemination is currently a major research issue in wireless sensor networks(WSNs).Many studies focus on code dissemination in homogeneous WSNs,mainly using a broadcast approach to solve this problem;few studies on code dissemination in heterogeneous WSNs.Furthermore,broadcasting cannot readily be used to solve the heterogenous WSN code dissemination problem directly,which is where we have focused our attention.We transformed this problem into a minimum non-leaf nodes(MNN) Steiner tree problem.We designed a scalable multicast protocol,named Heterogeneous Sensor Networks Scalable Reprogramming Protocol(HSR) to solve the MNN problem.HSR can build different multicast trees according to different nodes or code modules to disseminate different codes to them.HSR is able to approximate the MNN tree problem to a ratio of ln|R|(R is the set of all destinations) best known lowest bound.Therefore,the communication cost is significantly decreased and the total energy required by WSNs is reduced.We further designed two scalable schemes,special routing log and hops-restricted local broadcast,which compress the multicast tree information and deliver the multicast messages without loss.We also designed a 3-stage pipeline to speed up the transmission of packets,which alleviated interference and hidden terminal issues.We evaluated our design through comprehensive simulations and prototype implementations on Mica2 motes.Experimental results demonstrate that HSR outperforms previous protocols including the most recent studies on Sprinkler and uCast.