Modified Power Control Approach Based on CSMA/CA of Wireless Ad hoc Network

基于CSMA/CA机制,提出了一个改进的功率控制算法,用于解决传统的bASIC方案中,由于功率控制的引入而产生的非对称链路对节点传输的碰撞问题,它通过简单地修改802.11MAC层协议,采用变长的rTS/CTS来使载波侦听环中的节点获得关于dATA/ACk传输的分组大小及功率强度信息,从而有效地避免碰撞与重传。仿真结果说明,该方法不仅可以节省能量,而且可以提高网络性能。Based on CSMA/CA scheme,an improved power control algorithm was proposed to solve the Asymmetric Link Problem introduced by power control of BASIC in Ad Hoc networks,which modified 802.11 MAC protocol by using variable size of RTS/CTS to gain the information of data size and power level in the area of carrier sense ring to avoid more collisions and retransmissions.Simulation result shows that the approach can not only save network energy,but also improve network performance.福建省青年创新基金资助项目(2006F3097);福建省自然科学基金资助项目(A0710022);集美大学优秀青年骨干教师基金资助项目(2008B002

Techniques and Applications in Wireless Mesh Networks

无线网状网(WMNs)由网状路由器节点和客户机节点组成,其中的网状路由器节点组成了无线网状网的网络骨干,其移动性很小。他们一起为无线网状网和其他常规无线网络的客户机节点提供网络的无线接入。WMNs技术结合了中心式控制的蜂窝网与分布式控制的无线自组织网的优点,可有效克服这两种技术的缺陷并显著提高无线网络的性能,已经成为下一代无线通信网络的研究热点之一。WMNs可为无线个域网、局域网、校园网、城域网的一系列应用提供高速无线宽带接入服务。虽然目前WMNs技术发展很快,但其协议栈各层仍存在许多有待研究的课题。首先简要介绍了无线网状网的结构与特点;随后重点分析了其主要的几个应用领域;最后探讨了WMNs各协议层的研究现状与关键技术,并分析了该技术存在的问题及未来的研究方向。Wireless Mesh Networks(WMN) consist of mesh routers and mesh clients,where mesh routers have minimal mobility and form the backbone of WMNs.They provide network access for both mesh and conventional clients.WMNs are anticipated to resolve the limitations and to significantly improve the performance of wireless Ad Hoc networks and mobile cellular networks.They are undergoing rapid progress and inspiring numerous deployments.WMNs will deliver wireless broadband services access for a large variety of applications in personal,local,campus,and metropolitan areas.Despite recent advances in WMNs,many research challenges remain in all protocol layers.This paper presents a detailed study on recent advances and application scenarios in WMNs,followed by discussing the system architectures and characteristics briefly.Finally,recent research and advanced techniques of each protocol layer are described,and some open issues are analyzed

Design of cross-layer security for wireless sensor network's

无线传感器网络(WSNs)发展迅速,可广泛应用于军事、工业及科学等领域。传感器网络在无线信道中工作,其节点有限的能源、计算能力、存储能力使得其面临着严重的安全问题。已提出的许多安全方法都基于分层设计的概念。分析了分层安全设计的局限性,回顾了现存的W SNs的安全设计方案,提出了一些新的跨层解决办法,并指出了传感器网络中跨层安全的研究方向。Wireless sensor networks(WSNs) are developing rapidly,it will be employed in a wide variety of applications ranging from military,industrial and social.Due to their constraints in computation,memory,and power resources,security is a challenge in these networks.Many security methods of WSNs based on the concept of layered-design have the limit,the state of art security design method of WSNs is overviewed,several new cross-layer solve methods are proposed,and the research direction of cross-layer design for the security of WSNs is point out.福建省自然科学基金资助项目(A00440004

Energy Saving Route Finding Mechanism in Underwater Acoustic Sensor Networks

提出了水声传感网中能量有效的路由方案.结合水声信道的特点对水下传感网中的能耗因素进行分析,得出给定源宿节点之间的距离时路径消耗总能量与中继节点数的关系.对定向扩散协议进行改进,在初始化阶段根据汇聚节点和邻居节点的地理信息,求出源节点到目的节点的理想的最优能量路径.仿真结果证明,该方案能减少洪泛,只需选择1条较优路径,有效地节省了能量.An energy-efficient routing scheme is presented for underwater acoustic sensor networks(UW-ASN).Firstly,the factors affecting energy consumption in UW-ASN are analyzed in light of underwater channels,the relationship between numbers of relay nodes and energy consumption is obtained for given source-destination distance.The directed diffusion routing scheme is modified in the initial diffusion phase to find the optimal route based on the geographic information between a sink node and its neighboring nodes.Simulation shows that the proposed scheme can reduce the flooding cost,select an energy-efficient route,and save more energy.国家自然科学基金项目(60672046);集美大学优秀青年骨干教师基金项目(2008B002

A Congestion-aware Cross-layer Routing Scheme of Ad Hoc Networks with Multi-rate Mechanism

利用跨层设计的思想,论文提出了一种自适应多速率机制下,基于节点信息的AdHoc路由算法。根据物理层SNR的测量,结合MAC层的信息进行延迟估计,引入一种新的路由度量来选择路径,避开拥塞,减少延迟,提高网络吞吐量,从而能改善网络的整体性能。This paper proposes a cross-layer routing scheme based on information monitored by nodes for Ad Hoc networks supporting multi-rate mechanism.A new routing metric is introduced to take SNR measure on physical layer and delay estimate on MAC layer into account.With this metric,the routing algorithm tends to choose routes with wider bandwidth,lower delay,and less congestion.It demonstrates that the proposed scheme improves the performance of Ad Hoc work.清华-高通无线通信研究中心资助项

The Current Situation and Protection Measures of Amphibians and Reptiles Diversity of Huaihe River basin in Anhui

经过调查统计,发现淮河流域(安徽段)现有两栖动物11种,其中古北界2种,东洋界5种,广布种4种;爬行动物23种,属于古北界4种,东洋界13种,广布种6种。区系特点明显,属于古北界向东洋界的过渡区,东洋界和广布种种类分布相对丰富。相似系数分析表明沱湖和女山湖相似系数最高,说明其生境和其他两个保护区相比更为优越。此研究有助于了解该地区两栖爬行动物的多样性现状,为进一步加强资源的保护和可持续利用提供参考。The amphibians and reptiles diversity of Huaihe River basin in Anhui has been investigated and studied.The result indicates that 11 amphibian species have been found,2 of them are pale arctic realm,5 oriental species and 4 widespread species.23 reptile species have been found,4 of them are pale arctic realm,13 oriental species and 6 widespread species.The fauna feature was obvious.The pale arctic species are seldom,the oriental species and the widespread species are rich.Analysis indicates that the similar coefficient of Tuohu and Nvsanhu are the highest.The conclusion is that the diversity of amphibians and reptiles in this area can be illustrated;the environment and wildlife resources can be utilized reasonably after more protection.安徽科技学院重点学科建设基金项目(YZD2004-19)资

Cross-layer scheme in wireless sensor networks based on power control

无线传感器网络(W SNs)协议设计中既要考虑网络性能,又要考虑能量消耗。由于考虑的因素众多,传统的分层方法通常不能满足多个目标。提出一种基于功率控制的跨层路由方案,基于微经济学中效用的概念,通过对每个链路的功率进行控制,减少不必要发送功率,减少节点之间相互干扰,节省能耗。通过基于效用的路由度量,均衡网络性能,延长网络生存期。When designing wireless sensor networks(WSNs)protocol,not only network performance is considered,but also energy consumption is considered.Tradition layered design method can not satisfy several object parameters in the same time.A cross-layer scheme based on power control is proposed.It can reduce unnecessary energy and the interference between nodes by control power of every links.It can avoid selection of the route of lower battery capacity,which can improve overall network performance.福建省青年创新基金资助项目(2006F3097

Simulation and Analysis of Channel Assignment Strategy in IEEE802. 11b-Based Mesh Networks

中文摘要: 研究无线 Mesh网在繁忙区域增加接入点(AP)时 ,各种信道分配策略对网络性能的影响.首先研究了在多个 AP和多个用户的热点环境中的容量平衡机制 ,然后分析了在物理层使用 IEEE 802. 11b 标准提供的多重叠信道时对每个AP的影响 ,最后通过实测试验和 NS2 仿真 ,研究了信道条件、 节点密度、 信道接纳策略以及 MAC协议对吞吐率和公平 性的影响.结果证明 ,在网络中同一区域存在多个 AP时 ,由于有限的频谱和无线介质特性 ,增加新的 AP并不与系统容量成正比 ,反而会因为竞争和干扰降低这个区域的吞吐量. 3 种分配策略都存在一定的局限性 ,因此需要进一步考虑其它有效措施来提高系统容量. 英文摘要：The purpose of this paper is to study the affecting factors of channel assignment strategy on the performance of wireless Mesh network (WMN) when the number of APs is increased in a hot-spot (a crowded area with heavy traffic) . We first study mechanisms to balance the capacity of hot-spots in a scenario with multiple APs and many wireless users. Then we analyze the impact of separating each AP at the physical layer using multiple overlapping channels as provided by the IEEE 802. 11b standard. Finally we perform an extensive set of measurement s and ns-2 simulations to study the impact of factors such as channel conditions , node density , channel allocation policies , and MAC protocol on throughput and fairness. The result shows that , due to the shared nature of the wireless medium and limited spectrum , the addition of new AP in the area with multiple APs does not increase the total system capacity proportionally , but can significantly degrade the total throughput of the region as a result of interference and contention.Three channel assignment st rategies considered all have their own limitations. It is necessary to use other ways to improve the network performance.福建省青年创新基金 (2006F3097) ,福建省自然科学 金(A0710022) ,清华2高通联合研究中心资

Transmission power control and cross-layer optimization in wireless Ad Hoc networks

无线自组织网节点功率有限,如何有效利用节点电量、改善网络性能是自组网领域研究的关键问题。首先讨论了节点传输功率对各协议层的影响,并归纳出功率控制的设计原则;然后分类介绍和比较了几种主要的控制机制。在传统协议分层研究的基础上,提出了对传输功率控制进行跨层优化的设计思想,并对运用跨层优化的困难给予了阐述;最后给出了传输功率控制领域最新的一些研究方向。The power of wireless node is limited,so how to utilize the energy efficiently and how to improve the performance of network are the key topics in the research of wireless Ad Hoc networks.The relation(between) the transmission power and the protocol layer is discussed at first,and the design principles are (concluded).Some primary mechanisms of the power control are then introduced and compared.On the basis of tradition layering design,cross-layer optimization is proposed,some difficulties are discussed and the novel research directions are given.清华—交通无线通信研究中心资助项目;; 福建省青年科技人才创新项目(20033J016

formalized approach for componentized software process modeling

为了解决当前软件过程重用方法中存在的问题, 特别是由于缺乏对软件过程组件及其操作法则的精确定义所带来的重用中的低效率问题, 介绍了一种形式化的组件化软件过程建模方法(componentized software process modeling, 简称CSPM).CSPM提供了形式化定义可重用软件过程的机制, 并且给出了将过程组件组合成过程模型的 一系列操作法则. 利用CSPM方法, 能够以严格的方式对软件过程组件进行重用, 并且有效地避免了传统非形式化建 模方法中因歧义而有可能引起的潜在错误.CSPM还可以将对组装后的软件过程模型针对某些特定性质的验证问 题转化成对其对应组件的一系列子验证问题, 从而通过指数地减少需要搜索的状态空间规模, 将原来在某些特定环 境下不实用的验证问题简化成验证代价较小的一系列问题国家自然科学基金; 国家高技术研究发展计划(863); 国家重点基础研究发展计划(973)To address the problems of current approaches in software process reuse, in particular the low efficiency in reuse for the operational rules and for the lack of a precise definition of process components, a formalized approach for componentized software process modeling (CSPM) is presented in this paper. CSPM provides a mechanism to support the formal definition of reusable software process components and presents a series of rules to turn process components into a process model. By using CSPM, the reusage of process components can be conducted in a rigorous manner, and the potential errors caused by ambiguity in traditional non-formal modeling methods can be effectively avoided. CSPM can also turn the verification of a combined process model, against certain properties, into a series of sub-problems into its own corresponding components, making an original infeasible problem, under certain circumstances, into feasible ones by exponentially reducing the state space needed to be explore