Receiver-initiated medium access control protocols for wireless sensor networks

One of the fundamental building blocks of a Wireless Sensor Network (WSN) is the Medium Access Control (MAC) protocol, that part of the system governing when and how two independent neighboring nodes activate their respective transceivers to directly interact. Historically, data exchange has always been initiated by the node willing to relay data, i.e. the sender. However, the Receiver-Initiated paradigm introduced by Lin et al. in 2004 with RICER and made popular by Sun et al. in 2008 with RI-MAC, has spawned a whole new stream of research, yielding tens of new MAC protocols. Within such paradigm, the receiver is the one in charge of starting a direct communication with an eligible sender. This allows for new useful properties to be satisfied, novel schemes to be introduced and new challenges to be tackled. In this paper, we present a survey comprising of all the MAC protocols released since the year 2004 that fall under the receiver-initiated category. In particular, keeping in mind the key challenges that receiver-initiated MAC protocols are meant to deal with, we analyze and discuss the different protocols according to common features and design goals. The aim of this paper is to provide a comprehensive and self-contained introduction to the fundamentals of the receiver-initiated paradigm, providing newcomers with a quick-start guide on the state of the art of this field and a palette of options, essential for implementing applications or designing new protocols.     

无线多跳网络GeoGRID协议研究

Geocast是一种基于方向性投递的无线多播路由协议,能够减少冗余数据包,缩短多播时延。现有Geocast协议并不适用于稀疏网络环境,存在时延较大、数据冗余较高等缺陷。为了提高GeoGRID协议在稀疏网络中的性能,提出了GeoGRID-LBM和A-GeoGRID两种新型协议,利用网关节点掌握两跳网关节点邻居的信息,减少信道竞争和数据包碰撞概率,仿真实验表明,这两种改进型GeoGRID能够将数据端到端时延减少14%,降低冗余数据包数量达26%。     

Fairness of medium access control protocols for multi-hop ad hoc wireless networks

It is an undisputed fact that fairness is an important element of a well-designed medium access control (MAC) protocol for multi-hop ad hoc networks. However, most popular MAC protocols still fail to attain an acceptable level of fairness in media access although several enhancements have been proposed in the past. These proposed enhancements are effective only in limited scenarios. It is our objective in this paper to do the following: (i) analyze the fairness problem; (ii) identify and analyze the three main causes leading to the fairness problem, namely, the lack of synchronization problem (LSP), the double contention areas problem (DCP) and the lack of coordination problem (LCP); (iii) based on the analysis, propose a new MAC protocol named the extended hybrid asynchronous time division multiple access (EHATDMA) as a solution. For better assessment of fairness, we have designed an index named max–min fairness index, which is scenario-independent and reflects the difference between the fair sharing provided by a protocol and the ideal max–min fair sharing. Comprehensive simulations have been carried out to compare the fairness of our protocol with the existing ones. Simulation results show that although the existing protocols employ various enhancements meant to improve the fairness property, most of them are still strongly biased towards throughput when a conflict between throughput and fairness arises. In addition, the fairness performance of these protocols varies widely from one scenario to another. On the other hand, EHATDMA strikes a good balance between throughput and fairness. It delivers a consistently high level of fairness regardless of network topology, traffic load and radio parameters, yet maintains high throughput whenever possible. Our simulation results also reveal that the most important mechanism affecting the fair sharing of radio channels among flows is the non-work-conserving mechanism.     

无线传感器网络路由协议研究进展及发展趋势*

描述了无线传感器路由协议所面临的问题与挑战,分析和比较了典型的平面路由协议及层次路由协议。最后总结了理想路由协议应该具有的特点以及路由协议未来的研究策略及发展趋势。     

Contention-free MAC protocols for asynchronous wireless sensor networks

A MAC protocol specifies how nodes in a sensor network access a shared communication channel. Desired properties of a MAC protocol are: it should be contention-free (avoid collisions); it should be distributed and self-stabilize to topological changes in the network; topological changes should be contained, namely, affect only the nodes in the vicinity of the change; it should not assume that nodes have a global time reference, that is, nodes may not be time-synchronized. We give a set of TDMA-based MAC protocols for asynchronous wireless sensor networks satisfying all of these requirements. The communication complexity, number and size of messages, for the protocols to stabilize is small, poly-logarithmic in the network size. A preliminary version of the paper appears in the Proceedings of the 18th Annual Conference on Distributed Computing (DISC 2004), LNCS 3704, pp 245–259, Trippenhuis, Amsterdam, The Netherlands, October 2004.     

Access protocols for circuit/packet switching networks

This paper discusses two possible designs of access protocols for integrated computer networks with combined circuit and packet switching capabilities. The special features of these protocols are examined. Existing segregated protocols, i.e. pure circuit or packet protocols, are evaluated with future integration in mind.     

一种新的无线传感器网络均匀分簇路由协议

针对LEACH算法中,簇头位置分布不合理时导致的簇内通信能耗不均和簇的覆盖区域重叠的问题进行了改进,提出了LEACH_UD算法,一是在簇头的初次选举阶段,要考虑簇头之间的距离,使簇头大致均匀地分布在监测区域;二是取消LEACH协议中每轮重新成簇所带来的额外能量消耗,当初次簇头确定以后,簇的数量和分布不再变化,每一个簇的下一轮簇头由上一轮的簇头根据节点的能量情况来指定。用NS2对LEACH算法和LEACH_UD算法进行了仿真和比较,验证了LEACH_UD算法的有效性。     

无线传感器网络中的广播认证协议

在总结广播认证协议理想属性的基础上,对现有基于数字签名技术和对称加密技术的广播认证协议优缺点进行了分析讨论,并指出其对无线传感器网络广播认证协议设计的借鉴价值。将广播认证协议中的参数初始化和密钥更新等与密钥管理相关的问题归结为认证系统的完备性问题,并指出现有技术方案在解决该问题时存在的缺陷。初步探讨了无线传感器网络广播认证协议分级安全功能支持的意义,并给出了相应的方案设计思路。     

宽带无线IP网络安全体系结构模型

由于BWIP网络的非对称性特点,现有ISO/IEC7498-2、IPsec、WAP、3GPP、CDSA等安全体系结构框架都不能完全满足未来BWIP网络的安全需求。提出了一种适合未来BWIP网络的安全体系结构模型,该模型对BWIP网络所涉及的网络管理、安全操作、AAA、PKI、安全策略实施等技术进行了有机集成。给出了BWIP网络安全体系结构流入和流出的详细处理流程,并指出未来BWIP安全体系结构的研究方向。     

无线传感器网络多径路由协议综述

由于无线传感器网络不同于传统的自组织网络,已有自组织网络路由协议不能有效应用于传感器网络中.文献中已提出不少无线传感器网络路由协议,但这些协议大多针对单路径情况.当链路失效时,单径路由协议需要重新发现新的路由,从而会对传输延时、能耗和可靠性带来较大影响.采用多径路由协议可弥补单径路由协议的不足,有利于提高数据传输的可靠性和实现负载平衡.通过对目前文献中几种典型的多径路由协议的分析和比较,指出进一步研究中值得关注的问题.     

能耗均衡的无线传感器网络两级路由协议*

传感器网络分簇路由协议研究的一个关键问题是如何最优化组簇,既能有效降低簇内节点能耗,又能均衡整个网络能耗。为此,提出一种能耗均衡的网络两级分层分簇路由协议。协议底层应用PSO算法实现网络节点最优化分簇;上层选择总簇头节点负责收集、融合簇头数据并发送至基站。仿真结果表明,本协议能有效降低节点死亡速度,延长网络生存周期。     

A two-layer architecture for economically optimal process control and operation

A two-layer architecture for dynamic real-time optimization (or nonlinear modelpredictive control (NMPC) with an economic objective) is presented, where the solution of the dynamic optimization problem is computed on two time-scales. On the upper layer, a rigorous optimization problem is solved with an economic objective function at a slow time-scale, which captures slow trends in process uncertainties. On the lower layer, a fast neighboring-extremal controller is tracking the trajectory in order to deal with fast disturbances acting on the process. Compared to a single-layer architecture, the two-layer architecture is able to address control systems with complex models leading to high computational load, since the rigorous optimization problem can be solved at a slower rate than the process sampling time. Furthermore, solving a new rigorous optimization problem is not necessary at each sampling time if the process has rather slow dynamics compared to the disturbance dynamics. The two-layer control strategy is illustrated with a simulated case study of an industrial polymerization process.     

基于无线Mesh网路由协议的研究及优化

根据无线Mesh网络的结构特点,对现有的路由协议进行了分析,并针对其中一种典型的路由协议AODV延时过大的缺点进行了优化,即Ⅰ-AODV。其在AODV中引入表驱动的机制,增加维护的邻居节点数目,获得更多节点的路由信息,在路由建立时达到降低网络延时的目的。最后通过仿真软件NS-2进行了模拟测试,测试结果表明,Ⅰ-AODV的网络延时等网络性能明显得到了改善。     

基于业务区分的无线多媒体传感器网络QoS体系结构

无线多媒体传感器网络（WMSNs）的网络服务质量（QoS）一直是人们关心的核心问题,然而目前WMSNs的QoS保障研究主要针对单个协议层或特定应用场景,缺少系统性的QoS体系框架研究。结合无线传感器网络自身特点,利用图论对网络进行建模。在此基础上,提出一种三层可计算QoS指标体系,并根据各种应用不同QoS需求将应用分为四类,设计出一种基于业务区分的无线多媒体传感器网络QoS体系结构（DQoSAW）。以传输MPEG视频流为例对DQoSAW进行验证,实验结果表明DQoSAW能够显著改进WMSNs的整体性能。     

TinySOA: a service-oriented architecture for wireless sensor networks

Wireless sensor networks provide the means for gathering vast amounts of data from physical phenomena, and as such they are being used for applications such as precision agriculture, habitat monitoring, and others. However, there is a need to provide higher level abstractions for the development of applications, since accessing the data from wireless sensor networks currently implies dealing with very low-level constructs. We propose TinySOA, a service- oriented architecture that allows programmers to access wireless sensor networks from their applications by using a simple service-oriented API via the language of their choice. We show an implementation of TinySOA and the results of an experiment where programmers developed an application that exemplifies how easy Internet applications can integrate sensor networks.

无线传感器网络的覆盖控制

覆盖控制作为无线传感器网络中的一个基本问题,在国内外已经取得了一些研究成果。根据不同的性质,覆盖控制问题可以划分为不同的类型(如,静态覆盖和动态覆盖、确定性覆盖和随机性覆盖)。主要针对静态覆盖(区域覆盖、点覆盖、栅栏覆盖)问题中一些典型算法,分类进行了描述,并比较了它们之间的优缺点,最后,指出了需要进一步的研究工作。     

无线传感器网络中的拓扑控制 *

拓扑控制是无线传感器网络研究中的核心问题之一 ,它对于提高网络生存周期、降低通信干扰、提高 MAC和路由协议、保证网络连通和覆盖质量、提高网络服务等具有重要意义。阐述了拓扑控制技术研究的进展,首先描述了拓扑控制及其方法、评价标准 ,然后从平面网络、层次型网络拓扑控制介绍了一些代表性的研究工作 ,并指出了这些工作存在的不足 ,最后总结了研究现状中存在的问题以及拓扑控制研究的发展方向。     

基于时分复用的无线传感器网络MAC协议研究

对近年来无线传感器网络(W SNs)的基于时分复用(TDMA)的媒质访问控制(MAC)协议的最新研究进展进行了讨论和综述,描述了设计W SNs的MAC协议应该考虑的问题,详细论述了传感器网络的MAC协议的能量有效性问题,着重对一些具有代表性的基于TDMA的MAC协议进行对比、分析,并在此基础上提出了将来设计这类MAC协议的方向和建议。     

基于配对的无线网快速密钥协商协议

针对低频无线网通信速率低、时延长等特点,提出了一套用于移动终端与中心节点动态数据传输的密钥管理协议,单轮消息交换即可完成密钥协商,并提出了降低终端运算量的改型方案。协议满足前向安全性、会话密钥泄露的安全性、个人密钥泄露的安全性,无不明密钥共享,单方不能控制密钥生成。