WSN中基于云计算的动态频率分配研究

随着无线传感器网络的快速发展,频谱需求急速增长,频谱资源日渐紧缺,无线传感器网络频率的高效分配已成为一个亟需解决的难题。为了提高频谱的利用效率和应对无线传感网络中多节点频率信息动态配置问题,提出了一种基于云计算的WSN动态频率分配系统。该动态频率分配系统在无线传感器网络的无线通信框架上,利用云资源调度、分布式数据管理、自适应分析决策支持等技术,实现对无线传感器网络中频率资源的动态分配。     

无线多媒体传感器网络研究

无线多媒体传感器网络(WMSNs)是在传统无线传感器网络(WSNs)的基础上发展起来的具有音频、视频、图像等多媒体信息感知功能的新型传感器网络,具有广阔的应用前景。该文介绍了WMSNs的概念,分析了WMSNs区别于传统WSNs的个性化特点。对节点系统、MAC协议、路由协议、多媒体信息处理等关键技术的国内外研究现状、面临的问题和可行的解决方案进行了深入探讨。最后对WMSNs亟待解决的问题和发展趋势进行了总结。     

分簇无线传感器网络中的频谱感知方案

无线传感器网络中的节点众多,节点之间仅依靠频谱资源管理机制分配的频段进行数据传输会造成频谱资源紧张。针对这一问题,将认知无线电技术引入分簇的无线传感器网络,并且考虑分簇无线传感器网络节点的能量受限问题提出了一种节能的频谱感知方案。此方案首先让簇内的节点采取双门限能量检测的协作频谱感知方法,在满足目标检测概率和虚警概率的条件下,确定进行频谱感知的最少节点数,降低系统能耗。其次,通过选择合适的簇内节点进行频谱感知,使簇内节点的能耗均衡,簇的生命周期得到延长。     

无线认知电传感器网络动态频谱管理技术研究

WCSN(无线认知传感器网络)可以定义为无线认知传感器节点的分布式网络,它能够感知事件信号,机会地使用频谱空洞,并采用多跳方式,完成信息的动态协同通信,最终满足各种应用需求.文章分析了WCSN的基本概念和优势,给出了无线认知传感器网络节点硬件结构.研究了WCSN频谱感知、频谱分析决策和频谱切换技术的构成,列举了无线认知...     

基于分簇的无线多媒体传感器网络数据聚合方案研究

该文提出了一种基于分簇的无线多媒体传感器网络(WMSNs)数据聚合方案(Cluster-based Data Aggregation Algorithm, CDAA)。利用新的分簇方法和数据聚合策略,CDAA可以有效延长网络生命期。根据多媒体节点数据采集的方向性和节点剩余能耗,该文提出新的无线多媒体传感器网络的分簇方法,并基于该分簇方法进行网内多媒体数据聚合。仿真结果表明,该方法能够有效减少冗余数据的传送,与LEACH, PEGASIS等传统WSNs路由协议和针对WMSNs的AntSensNet协议相比,在能耗均衡和节能方面表现出更好的性能。     

无线认知传感器网络研究

无线认知传感器网络(WCSN)可以定义为无线认知传感器节点的分布式网络,它感知事件信号,机会地使用频谱空洞,并采用多跳方式,完成信息的动态协同通信,最终满足各种应用需求。文章分析了无线认知传感器网络(WCSN)的基本概念和优势,给出了无线认知传感器网络节点硬件结构,研究了Ad Hoc式、分簇式、异构分级式和移动式四种无线认知传感器网络拓扑结构,列举了无线认知传感器网络的应用领域。     

认知无线电系统中频谱感知方法的研究

由于无线通信技术的飞速发展，因此无线资源频谱日趋紧张．而另一方面现有无线通信网络采用的固定频谱分配策略导致许多已分配的频段在大多数情况下未能被充分利用。认知无线电技术的出现为提高频谱利用率提供了一条新的思路．认知无线电的一个重要要求就是能够动态的感知并接入频段，这就需要人们能够感知出空闲频段。论文主要介绍了认知无线电系统中的频谱感知方法，并运用能量检测法对对OFDM信号进行了仿真分析．     

基于改进PSO的WMSNs覆盖增强算法

对无线多媒体传感器网络(WMSNs)的覆盖增强问题进行了研究.在WMSNs网络中,视频、图像节点的视角范围有限,只能监控周围的部分区域.由于节点数量众多、部署方式受限等原因,网络中往往存在大量的监测重叠与监控盲区,需要对各节点的感知方向进行优化,以提高网络的监控质量.文中基于有向感知模型,提出了一种覆盖增强算法MCE.MCE对各节点的感知方向进行调整,并使用了改进的PSO算法来计算求解.仿真实验表明,MCE算法能够有效地提高网络的覆盖率.     

认知无线电与WLAN的融合技术

随着无线局域网(WLAN)的迅速普及,有限的可用频谱资源日益紧张。认知无线电(CR)技术具有动态重用空闲频谱资源的能力,可以有效提高频谱利用率,得到了无线通信行业的关注。通过将CR技术与无线局域网相融合,可以为无线局域网提供更为灵活的通信,扩展无线局域网的工作频段。IEEE 802.11y无线局域网标准的制定进一步推动了CR技术的应用。CR技术与无线局域网融合的过程中,还需要完善包括频谱感知、频谱资源共享和分配、动态频率选择和传输功率控制等技术。     

基于WMSNs的图像压缩技术研究

无线多媒体传感器网络(WMSNs)通过数量庞大的终端传感节点实现对外部环境的监测,并通过无线网络进行通信。随着外部环境的不断变化,对无线多媒体传感器网络的环境监测性能也提出了新的需求,如将各类多媒体资源加入到环境监测中,以获得更为细化精准的监测信息。文章综合分析了WMSNs图像压缩技术的研究发展现状,指出了现有的WMSNs图像压缩技术的不足以及应用WMSNs的图像压缩技术应满足的要求;并对图像压缩中的三种主要变换,即DCT变换、小波变换、双正交叠式变换(LBT)进行了分析比较。同时根据WMSNs的特点,提出了基于双正交重叠变换技术(LBT)的多节点协同图像压缩优化算法设计策略,有效解决了WMSNs的单节点图像处理功能受限问题。     

Wireless Multimedia Sensor Networks: Applications and Testbeds

The availability of low-cost hardware is enabling the development of wireless multimedia sensor networks (WMSNs), i.e., networks of resource-constrained wireless devices that can retrieve multimedia content such as video and audio streams, still images, and scalar sensor data from the environment. In this paper, ongoing research on prototypes of multimedia sensors and their integration into testbeds for experimental evaluation of algorithms and protocols for WMSNs are described. Furthermore, open research issues and future research directions, both at the device level and at the testbed level, are discussed. This paper is intended to be a resource for researchers interested in advancing the state-of-the-art in experimental research on wireless multimedia sensor networks.      

Novel congestion control approach in wireless multimedia sensor networks

Data generated in wireless multimedia sensor networks (WMSNs) may have different importance and it has been claimed that the network exert more efforts in servicing applications carrying more important information. Nevertheless, importance of packets cannot generally be accurately represented by a static priority value. This article presents a dynamic priority based congestion control (DPCC) approach that makes two major innovations in WMSNs. First, DPCC employs dynamic priority to represent packet importance. Second, it prioritizes the local traffic of motes near the base station when WMSN is highly congested. Simulation results confirm the superior performance of the proposed approach with respect to energy efficiency, loss probability and latency as well.     

Energy efficient distributed steganography for secure communication in wireless multimedia sensor networks

A secure communication mechanism is necessary in the applications of Wireless Multimedia Sensor Networks (WMSNs), which is more vulnerable to security attacks due to the presence of multimedia data. Additionally, given the limited technological resources (in term of energy, computation, bandwidth, and storage) of sensor nodes, security and privacy policies have to be combined with energy-aware algorithms and distributed processing of multimedia contents in WMSNs. To solve these problems in this paper, an energy efficient distributed steganography scheme, which combines steganography technique with the concept of distributed computing, is proposed for secure communication in WMSNs. The simulation results show that the proposed method can achieve considerable energy efficiency while assuring the communication security simultaneously.     

无线多媒体传感器网络路由协议研究

传统的无线传感器网络(Wireless Sensor Networks,WSNs)路由协议不能很好地适应多媒体数据流的传输.近来,提出了一些无线多媒体传感器网络(Wireless Multimedia Sensor Networks,WMSNs)路由协议.本文首先讲述了WMSNs服务质量保障路由问题及其面临的挑战,从五...     

Cooperative Caching in Wireless Multimedia Sensor Networks

The recent advances in miniaturization and the creation of low-power circuits, combined with small-sized batteries have made the development of wireless sensor networks a working reality. Lately, the production of cheap complementary metal-oxide semiconductor cameras and microphones, which are able to capture rich multimedia content, gave birth to what is called Wireless Multimedia Sensor Networks (WMSNs). WMSNs will boost the capabilities of current wireless sensor networks, and will fuel several novel applications, like multimedia surveillance sensor networks. WMSNs introduce several new research challenges, mainly related to mechanisms to deliver application-level Quality-of-Service (e.g., latency minimization). To address this goal in an environment with extreme resource constraints, with variable channel capacity and with requirements for multimedia in-network processing, the caching of multimedia data, exploiting the cooperation among sensor nodes is vital. This article presents a cooperative caching solution particularly suitable for WMSNs. The proposed caching solution exploits sensor nodes which reside in “positions” of the network that allow them to forward packets or communicate decisions within short latency. These so-called “mediator” nodes are selected dynamically, so as to avoid the creation of hot-spots in the communication and the depletion of their energy. The mediators are not more powerful than the rest of the nodes, but they have some special role in implementing the cooperation among the sensors. The proposed cooperative caching protocol includes components for locating cached data as well as for implementing data purging out of the sensor caches. The proposed solution is evaluated extensively in an advanced simulation environment, and it is compared to the state-of-the-art cooperative caching algorithm for mobile ad hoc networks. The results confirm that the proposed caching mechanism prevails over its competitor.     

基于PSO的无线多媒体传感器网络覆盖增强算法

在无线多媒体传感器网络(Wireless Multimedia Sensor Networks,WMSNs)中,由于节点部署的不合理,往往存在较多的监控盲区,影响了网络的服务质量。为了提高网络的覆盖率,在有向感知模型基础的基础上,提出了一种基于粒子群算法的WMSNs覆盖增强算法PSOCE。PSOCE算法以网络覆盖率为优化目标,以粒子群算法为计算工具,同时对节点的位置与主感知方向进行调整。仿真试验表明,PSOCE算法能够有效地改进WMSNs的覆盖质量,网络的覆盖率能提高6%～12%。     

QoS in Wireless Multimedia Sensor Networks: A Layered and Cross-Layered Approach

The emergence of wireless multimedia sensor networks (WMSN) has given birth to several civilian as well as defense applications. Some of the interesting applications employing low cost sensor nodes to manipulate rich multimedia content include traffic monitoring, border surveillance, smart homes, environment and habitat monitoring. Unlike the traditional sensor networks which are aimed at maximizing network lifetime by decreasing energy utilization, the main objective of WMSNs is optimized delivery of multimedia content along with energy efficiency. Multimedia communications in WMSNs, has stringent delay and high bandwidth requirement as compared to scalar data transfer in WSNs. Fulfilling these constraints in resource and energy constrained WMSNs is a huge challenge. In WMSNs, each layer of the protocol stack is responsible and fully involved in providing QoS guarantees. There is a need for new schemes at each layer of the protocol stack- from advanced coding techniques that reduce encoder complexity and achieve maximum compression to dynamic routing and MAC protocols that provide service differentiation and reduce end-to-end latency. In wireless sensor networks, where all layers have dependency on each other, QoS guarantees are possible through the cross layer interaction of different layers. This paper gives an overview of the different existing layered schemes in WMSNs, followed by a discussion on the significance and efficiency gains that can be achieved from cross layer interactions in WMSNs along with the review of the existing cross layer approaches. Finally, we identify the open research issues which have not been adequately addressed so far.     

Routing Protocol for Heterogeneous Hierarchical Wireless Multimedia Sensor Networks

Recently, wireless multimedia sensor networks (WMSNs) have emerged as one of the most important technologies, driven by the development of powerful multimedia device such as CMOS. WMSNs require several factors such as resource constraints, specific QoS, high bandwidth and so on. In this paper, we propose a hierarchical heterogeneous network model based routing protocol for WMSNs. In our proposal, proposed network model is classified into monitoring class, delivery class and aggregation class. Also we define two kinds of the routing path in order to ensure bandwidth and QoS. In simulation results, we illustrate the performance of our proposal.     

Joint Active Duty Scheduling and Encoding Rate Allocation Optimized Performance of Wireless Multimedia Sensor Networks in Smart Cities

In smart cities, wireless multimedia sensor networks (WMSNs) and mobile cellular networks (MCNs) play an important role in surveillance and management of living environment, i.e., structural health of buildings, urban transportation, and potential locations of future crime, etc. In WMSNs, the camera sensors (CSs) can capture multimedia contents from particular areas, packetize and transmit them to the cluster heads (CHs). The multimedia contents are then forwarded by the CHs, to the base stations (BSs) in MCNs, for monitoring and analyzing. The most challenge is that on the one hand, streaming multimedia contents at high data rate for high playback quality demands, particularly in video streaming applications, requires huge amounts of bandwidth and energy consumption. On the other hand, the wireless channels are inherently varying lossy and the CSs and the CHs are equipped with energy- and bandwidth-constrained capacity. In addition, due to high density of CSs deployed, many of them may monitor the same areas and capture many videos with high correlation, causing numerous redundant contents sent to the BSs, and thus more energy and bandwidth resources are wasted. In this paper, we propose a joint active duty scheduling and encoding rate allocation (ADS-ERA) model to optimize the performance of WMSNs. In particular, the ADS-ERA can minimize the capture, packetization, and transmission energy consumption while satisfying given limited bandwidth and high playback quality constraints. The ADS optimization problem is formulated and solved for optimally scheduling the active duties of the CSs to capture the videos with minimum capture energy consumption. By taking into the constraints on bandwidth and quality, we further formulate the ERA optimization problem and solve it for optimally allocating the encoding rates of the captured videos so that they are packetized and transmitted with minimum energy consumption. Simulation results demonstrate that the proposed ADS-EAR model significantly gain high performance of WMSNs, i.e., minimizing the consumption of capture, packetization, and transmission energy, utilizing the limited bandwidth efficiently, and providing high playback quality of received videos at the BSs.