Editorial

Wireless sensor network(WSN)is characterized by the dense deployment of sensor nodes that continuously observe physical phenomenon.The main advantages of WSN include its low cost,rapid deployment,self-organization,and fault tolerance.WSN has received tremendous interests of various research communities,and significant progresses have been made in various aspects including sensor platform development,wireless communication and networking,signal and information processing,as well as network performance eva...     

The performance impact of traffic patterns on routing protocols in mobile ad hoc networks

As mobile ad hoc network (MANET) systems research has matured and several testbeds have been built to study MANETs, research has focused on developing new MANET applications such as collaborative games, collaborative computing, messaging systems, distributed security schemes, MANET middleware, peer-to-peer file sharing systems, voting systems, resource management and discovery, vehicular computing and collaborative education systems. The growing set of diverse applications developed for MANETs pose far more complex traffic patterns than the simple one-to-one traffic pattern, and hence the one-to-one traffic pattern widely used in previous protocol studies has become inadequate in reflecting the relative performance of these protocols when deployed to support these emerging applications.As a first step towards effectively supporting newly developed and future diverse MANET applications, this paper studies the performance impact of diverse traffic patterns on routing protocols in MANETs. Specifically, we propose a new communication model that extends the previous communication model to include a more general traffic pattern that varies the number of connections per source node. We study the performance impact of traffic patterns on various routing protocols via detailed simulations of an ad hoc network of 112 mobile nodes. Our simulation results show that many of the conclusions drawn in previous protocol comparison studies no longer hold under the new traffic patterns. These results motivate the need for performance evaluation of ad hoc networks to not only include rich and diverse mobility models as has been done in the past but also include diverse traffic patterns that stress a wide set of protocol design issues.     

一类工业以太网络通信协议的设计与性能分析

工业网络协议的设计是网络控制系统分析和设计的重要内容.网络诱导的延时值越小,则越有利于系统的稳定和控制算法的设计.在工业以太网络通信协议(IECP)模型中,工业通信协议一般建立在传输层或是应用层.通过工业通信模式、数据报和IECP通信程序,详细介绍了IECP的设计.提出了网络协议的性能指标,指出实时性是最重要的指标,并通过实验系统,进行了基于TCP、UDP和IP的IECP的实时性比较.结果说明了基于不同层IECP的性能差异性.同时也证明了基于不同层IECP的可行性.     

Time delay characteristic of industrial wireless networks based on IEEE 802.15.4a

The IEEE 802.15.4a standard provides a framework for low-data-rate communication systems, typically sensor networks. In this paper, we established a realistic environment for the time delay characteristic of industrial network based on IEEE 802.15.4a. Several sets of practical experiments are conducted to study its various features, including the effects of 1) numeral wireless nodes, 2) numeral data packets, 3) data transmissions with different upper-layer protocols, 4) physical distance between nodes, and 5) adding and reducing the number of the wireless nodes. The results show that IEEE 802.15.4a is suitable for some industrial applications that have more relaxed throughput requirements and time-delay. Some issues that could degrade the network performance are also discussed.     

A taxonomy of multicast protocols for Internet applications

The continuous growth in applications that require communications among a group of hosts or simultaneous dissemination of data to multiple sites on the Internet has led to considerable interest in multicast communication. These applications have different quality of service requirements such as deadlines to response time and tolerance to data loss. Internet multicast protocols provide a spectrum of services to cater for the needs of a wide array of multicast applications. The design alternatives of a multicast protocol for a particular application may lead to different performance characteristics, for example higher utilization of network bandwidth vs lower protocol processing requirements. Therefore a framework is required to various design choices available to design multicast protocols and evaluate the performance tradeoffs associated with these alternatives. Motivated by such a need and by the evolution of multicast applications over the Internet, this article presents a taxonomy of multicast protocols and a common framework to evaluate their performance.     

遗传算法在WSN路由协议设计中的研究与应用

和传统无线网络的节点相比,无线传感器网络的节点有其特殊的地方:电源能量有限,通信能力有限以及计算能力有限,网络拓扑结构更加不稳定,这些特性使得以前研究很多的无线自组织网的网络路由协议不能直接应用于无线传感器网络.提出基于遗传算法思想来设计和优化无线传感器网络的路由协议,使得源节点和目的节点之间以及中间节点之间存在多条最佳路径,节点在进行路由选择的同时,最大限度来保证网络各节点的总体能量消耗最少,最终保证整个网络的残存性能有进一步的提高.     

Wireless control system design and co-simulation

This paper discusses the communication and control co-design and co-simulation of wireless networked control systems. The interactions between the network and the control system are considered, and general networking and control co-design solutions are proposed for wireless control applications. The PiccSIM simulator for wireless control system simulation is used to study the effects of specific network protocol and control algorithms in practice. Packet loss models based on measurements of real industrial radio environments are incorporated into the simulator. This allows the realistic evaluation of the suitability of the network protocols for wireless control applications. A network quality of service measure is introduced, which gives a direct relationship between the network and control performances. Two simulation cases show the capabilities of PiccSIM for wireless control application research and development, where the co-design issues and solutions are demonstrated in detail.     

多跳无线移动Ad Hoc网络路由协议的研究分析

无线移动Ad Hoe网络(MANET)作为可移动分布式多跳无线网络，没有预先确定的网络拓扑或网络基础设施以及集中控制．为了在如此的网络中促进通信，路由协议主要用于在节点之间发现路径．Ad Hoe网络路由协议的主要目的是网络拓扑的动态变化、任意两个节点之间建立一个使得通信总费用和带宽消费最少的正确和有效的通信路径．描述了设计移动Ad Hoe网络路由协议所面临的问题以及对它们的评价，详细比较了七种典型无线移动AdHoe网络路由协议的特性和功能，即DSDV，CGSR，WRP，AODV，DSR，TORA和ABR，为进一步的研究提出了新的课题．     

工业网络系统的感知-传输-控制一体化:挑战和进展

工业网络系统是融合工业控制和信息通信的多维动态系统，具有维度高、动态性强、工业通信协议和网络配置嵌入等特性，如何在网络环境下实现信息感知分布性、控制适应性、整体协调性，已成为工业网络系统研究的新挑战.本文简述了工业网络系统的内涵和主要特征，分析了感知-传输-控制一体化面临的挑战和关键问题；综述了分布式状态感知、适变传输、协同控制等关键技术的研究进展；对工业网络系统的未来研究方向和潜在应用前景进行了总结和展望.     

From versatility to auto-adaptation of the medium access control in wireless sensor networks

Recent deployments of wireless sensor networks have targeted challenging monitoring and surveillance applications. The medium access control being the main source of energy wastage, energy-efficiency has always been kept in mind while designing the communication stack embedded in spread sensors. Especially, versatile protocols have emerged to offer a suitable solution over multiple deployment characteristics. In this study, we observe to what extent versatility applies to dynamic scenarios in which communications do not respect specific communication paradigms. We first provide a performance evaluation of two well-reputed versatile protocols (B-MAC (Polastre et al., 2004 [17]) and X-MAC (Buettner et al., 2006 [4])) under the conditions of such a scenario. The obtained results convinced us to propose more than versatility and pre-configured solutions, that is auto-adaptation. We then introduce the main contribution of this paper, an auto-adaptive algorithm that allows one to adjust the previously mentioned protocols while the network is operating. We analyze to what extent it outperforms the previously obtained results.     

无线传感器网络MAC协议研究进展

在无线传感器网络体系结构中,MAC(medium access control)协议是保证网络高效通信的重要协议.无线传感器网络有着与传统无线网络明显不同的性能特点和技术要求,传统无线网络MAC协议无法应用于传感器网络,各种针对特定传感器网络特点的MAC协议相继提出.归纳无线传感器网络MAC协议的设计原则和分类方法,分析当前典型的各类MAC协议的主要机制,详细比较这些协议的特点、性能差异和应用范围.最后总结无线传感器网络MAC协议的研究现状,指出未来的研究重点.     

无线网状网中一种高吞吐量的路由策略

无线网状网（Wireless Mesh Network,WMN）是一种多跳、分布式的无线网络,可以提供多种宽带多媒体业务。目前,无线网状网的路由技术的研究还处于起步阶段。首先介绍当前几种著名的无线网状网路由协议,并分析了这些协议的不足,在此基础上提出一种新的路由算法,该算法综合考虑了链路质量、节点负载均衡、信道干扰三个主要因素,能够显著地提高网络性能。分析与仿真结果表明,该算法能显著地提高网络吞吐量和降低传输延时,并且具有良好的抗干扰性。     

Secure network coding for wireless mesh networks: Threats, challenges, and directions

In recent years, network coding has emerged as a new communication paradigm that can significantly improve the efficiency of network protocols by requiring intermediate nodes to mix packets before forwarding them. Recently, several real-world systems have been proposed to leverage network coding in wireless networks. Although the theoretical foundations of network coding are well understood, a real-world system needs to solve a plethora of practical aspects before network coding can meet its promised potential. These practical design choices expose network coding systems to a wide range of attacks.We identify two general frameworks (inter-flow and intra-flow) that encompass several network coding-based systems proposed in wireless networks. Our systematic analysis of the components of these frameworks reveals vulnerabilities to a wide range of attacks, which may severely degrade system performance. Then, we identify security goals and design challenges in achieving security for network coding systems. Adequate understanding of both the threats and challenges is essential to effectively design secure practical network coding systems. Our paper should be viewed as a cautionary note pointing out the frailty of current network coding-based wireless systems and a general guideline in the effort of achieving security for network coding systems.     

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.     

基于功率控制的无线传感器网络MAC协议研究

无线传感器网络是21世纪新兴的网络技术,它的出现使网络的发展进入一个新的阶段.近年来,对无线传感器网络介质访问控制协议的研究也越来越多.总结了近年来的研究成果,并针对S-MAC,T-MAC和D-MAC等几种典型的MAC协议进行了对比分析.研究出将功率控制机制引入到MAC协议中可以进一步减少能耗,给出了一种基于发射功率控制思想的MAC协议.PCSMAC协议.功率控制可以从直接的降低发送能量和间接的减少碰撞两个角度节约能耗,是一种有效的节能机制.仿真实验表明,引入功率控制后可以节约能耗达50%--96%左右.     

Energy-efficient multipath routing in wireless sensor network considering wireless interference

Due to the energy and resource constraints of a wireless sensor node in a wireless sensor network (WSN), design of energy-efficient multipath routing protocols is a crucial concern for WSN applications. To provide high-quality monitoring information, many WSN applications require high-rate data transmission. Multipath routing protocols are often used to increase the network transmission rate and throughput. Although large-scale WSN can be supported by high bandwidth backbone network, the WSN remains the bottleneck due to resource constraints of wireless sensors and the effects of wireless interference. In this paper, we propose a multipath energy-efficient routing protocol for WSN that considers wireless interference. In the proposed routing protocol, nodes in the interference zone of the discovered path are marked and not allowed to take part in the subsequent routing process. In this way, the quality of wireless communication is improved because the effects of wireless interference can be reduced as much as possible. The network load is distributed on multiple paths instead of concentrating on only one path, and node energy cost is more balanced for the entire wireless network. The routing protocol is simulated in NS2 software. Simulation result shows that the proposed routing protocol achieves lower energy cost and longer network lifetime than that in the literature.     

水声传感网MAC协议综述

海洋在人类发展中扮演着越来越重要的角色。水下通信技术作为人类认识海洋的重要手段,成为研究界的热点与难点。由于水下通信技术有不同于陆地无线通信的信道特点和性能要求,传统无线通信MAC(medium access controD协议难以直接应用于水声通信,因此相继提出针对各种应用场景的水声MAC协议。在简述水声传感网(Undcrwatcr Acoustic Sensor Nctwork,UWASN)特点和MAC协议设计准则后,根据信道获取方式将当前典型协议分为基于竟争和基于调度两大类。根据冲突处置方式进一步将基于竞争的协议分为随机多址和冲突避免,根据信道分配的动态性将基于调度的协议分为动态分配和静态分配。在此分类基础上,描述了近期出现的典型协议的设计思想、主要机制,并比较了协议在能耗、信道利用、吞吐量等方面的差异,最后指出提高MAC协议性能的发展方向。     

无线传感器网络分析与仿真

计算机仿真是通信网络研究的有效评估方法之一。无线传感器网络强调对目标现象及其属性的实时感知能力，支持对感知信息的本地处理和节点间协同处理，而传统网络仿真平台并不支持。从网络体系结构和典型应用场景入手，分析无线传感器网络仿真需求，提出结合传统网络通信性能、能耗控制和基础功能实现的网络性能评价指标，并给出基于NS-2的扩展设计和实现。     

无线传感器网络安全问题分析与研究

根据无线传感器网络的安全需求,重点分析了目前几种典型的路由协议,通过对多种传感器网络安全协议对比,指出了常用协议存在的局限性,提出了一种基于可信路由表的无线传感器网络安全路由协议,目标是实现以最可信的路由路径规避恶意节点,从而更适合无线传感器网络安全应用。     

The anatomy study of server-initial agreement for general hierarchy wired/wireless networks

The Byzantine Agreement (BA) plays a key role in fault-tolerant distributed system design. A number of solutions to the BA problem based on various network model assumptions have been proposed. However, most existing BA protocols are designed for pure wired or pure wireless networks. In practice, most current networks are combined wired and wireless environments. In this paper, we extend the BA problem over a combined wired/wireless network, consisting of both powerful computing stationary processor and low-power mobile processor. The communication overhead of BA protocol is inherently large and secure group communications are important. The protocols proposed in this paper use the hierarchical model concept to reduce the communication overhead and provide secure group communications well suited for combined wired/wireless networks.