Virus spreading in wireless sensor networks with a medium access control mechanism

In this paper, an extended version of standard susceptible-infected （SI） model is proposed to consider the influence of a medium access control mechanism on virus spreading in wireless sensor networks. Theoretical analysis shows that the medium access control mechanism obviously reduces the density of infected nodes in the networks, which has been ignored in previous studies. It is also found that by increasing the network node density or node communication radius greatly increases the number of infected nodes. The theoretical results are confirmed by numerical simulations.

The Design of an Intelligent Security Access Control System Based on Fingerprint Sensor FPC1011C

This paper deals with the design of an intelligent access control system based on the fingerprint sensor FPC- 1011C. The design uses the S3C2410 and TMS320VC5510A as the system processor. A fingerprint acquisition module and a wireless alarm module were designed by using the fingerprint sensor FPC1011C and GPRS module SIM100 respectively. The whole system was implemented wireless alarm through messages and GPRS-Internet in the GSM/GPRS web. In order to achieve the simple and high Real-time system, the μC-Linux system migration was also implemented.

Mobility Conscious Medium Access Control Scheme for Wireless Sensor Networks: A Conceptual Approach

Mobility in Wireless Sensor Network (WSN) presents distinctive challenges in Medium Access Control (MAC) scheme. Numerous MAC protocols for sensor networks assume that sensor nodes are static and focus primarily on energy efficiency. This work seeks to develop an improved mobility conscious medium access control scheme for wireless sensor networks with a view to enhance energy conservation on mobile sensor nodes. On this note, mobility patterns of different scenarios are modelled using Gauss Markov Mobility Model (GMMM) to determine the position and distance of the sensor nodes and how they are correlated in time.

定向接收低冲突率水声网络媒体接入控制协议

在全向水声通信网络场景中,较大的传播时延和较高的数据包碰撞率严重影响了网络性能。相比全向接收技术,声矢量传感器的声压和振速通过线性加权组合可以形成单边指向性,实现定向接收某个方向上的信号,进而提高网络的空间复用率。该文首先分析了声矢量传感器定向接收模式下的网络中断概率,验证定向接收技术网络应用的可行性。然后,提出了定向接收低冲突概率媒体接入控制协议(DRLCP-MAC)。该协议利用指向性接收波束握手机制建立稳定的数据传输链路,通过状态转移策略构建多对并行通信链路,缩小虚拟载波监听范围,提高网络的空间复用度。仿真结果表明,与水下冲突避免多址接入协议(MACA-U)和时隙地面多址接入协议(Slotted-FAMA)相比,DRLCP-MAC协议使信道接入成本降低了约50%和60%,网络吞吐量提升了约60%和400%,端到端时延降低了约50%和85%。

面向水下移动汇聚节点的媒体接入控制协议研究

针对水下移动传感网络(underwater mobile sensor network,UWMSN)中使用自主移动节点进行数据收集存在的拓扑结构不断变化、传输不可靠的问题,提出一种动态退避发送数据帧的自适应媒体接入控制(media access control,MAC)协议,通过将协议划分为控制阶段与数据阶段周期性地更新可建立通信的节点信息,根据当前周期获得的节点距离信息调度各节点数据传输顺序,利用水下环境的大传播时延计算各节点的回退发送数据帧的时间,使用数据重传机制提高传输的可靠性。采用OPNET网络仿真模拟器对提出的协议进行仿真和对比分析。仿真结果显示,协议在密度较低的小范围水下传感网络中可保证较高的投递成功率和较低的端到端时延,增大了网络吞吐量,提高了网络性能。

跨平台访问端传感网络串口通信多线程实现

串口是外部串行设备与计算机之间的关键数据传输通道,由于跨平台访问端的传感器数据来自不同平台,具有显著独立性,融合难度较大,直接影响多线程通信效率。提出一种针对跨平台访问端传感网络的串口通信多线程实现方法。构建跨平台访问端,采用统计概率置信度算法,修正或剔除传感网络数据中的异常值。从时间相关性和空间相关性,完成传感网络的数据融合。依据信标时序补偿网络时钟同步法、父子链路时序轮转调度法,分配多线程执行信息传输,实现跨平台访问端传感网络串口多线程通信。实验表明:当线程数量由1增加至16时,在低网络流量和高网络流量负载情况下,所提方法的传感网络延迟可控制在0.53 ms以内。且在相同传输错漏率下,所提方法的进程平均超限步数始终更低。

基于智能传感器和VB6.0/ACCESS的温湿度测量系统

运用VB6.0的串行通信控件,实现计算机与多个智能温湿度传感器的串行通信;在VB6.0环境下,调用ACCESS数据库进行数据保存。该方法实现了分散智能传感器的集中控制、数据的自动采集与自动保存。

ResearchonsecureaccessmechanismininternetofthingsbasedonTePA

以椭圆曲线密码算法和三元对等鉴别架构为基础，通过对物联网的基本概念、体系结构的分析，提出了一种基于椭圆曲线签名、三元鉴别的物联网安全接入机制。该机制强化了对物联网中无线传感器节点的鉴别，要求通信的任何一方在通信前必须通过其它两方的身份验证。从性能和安全等方面分析了该机制的可行性和可靠性，增强了物联网下对接入访问的安全控制，从而对物联网的建设发展起到了一定的建言作用。

电力基坑有害气体风险评估方法设计

为了提升风险评估准确率,设计了一种电力基坑有害气体风险评估方法。创新性地利用密度和加权方法改进聚类算法,实施电力基坑有害气体传感数据的挖掘。使用改进阈值函数去噪方法对传感器数据实施去噪处理。基于静态响应和动态响应构建传感器响应灵敏度控制模型,提高数据质量。基于机器学习中的图神经网络构建电力基坑有害气体风险评估模型,实现有害气体风险等级评估。测试结果表明,该方法能够实现风险等级评估,并将风险评估结果的准确率均值提升到95%以上。评估结果显示:工程中基坑4、基坑5、基坑6的风险评估等级为低等级;基坑2为中低等级;基坑1、基坑3、基坑8为中等级;基坑7为中高等级。该方法的评估结果可用于对电力基坑施工安全进行控制,具有实际工程应用价值。

CR-NOMA中基于深度确定策略梯度的能效优化策略

利用认知无线电非正交多址接入(cognitive radio non-orthogonal multiple access,CR-NOMA)技术可缓解频谱资源短缺问题,提升传感设备的吞吐量。传感设备的能效问题一直制约着传感设备的应用。为此,针对CR-NOMA中的传感设备,提出基于深度确定策略梯度的能效优化(deep deterministic policy gradientbased energy efficiency optimization,DPEE)算法。DPEE算法通过联合优化传感设备的传输功率和时隙分裂系数,提升传感设备的能效。将能效优化问题建模成马尔可夫决策过程,再利用深度确定策略梯度法求解。最后,通过仿真分析了电路功耗、时隙时长和主设备数对传感能效的影响。仿真结果表明,能效随传感设备电路功耗的增加而下降。此外,相比于基准算法,提出的DPEE算法提升了能效。

A Survey on Underwater Acoustic Sensor Networks: Perspectives on Protocol Design for Signaling, MAC and Routing

Underwater acoustic sensor networks (UASNs) are often used for environmental and industrial sensing in undersea/ocean space, therefore, these networks are also named underwater wireless sensor networks (UWSNs). Underwater sensor networks are different from other sensor networks due to the acoustic channel used in their physical layer, thus we should discuss about the specific features of these underwater networks such as acoustic channel modeling and protocol design for different layers of open system interconnection (OSI) model. Each node of these networks as a sensor needs to exchange data with other nodes;however, complexity of the acoustic channel makes some challenges in practice, especially when we are designing the network protocols. Therefore based on the mentioned cases, we are going to review general issues of the design of an UASN in this paper. In this regard, we firstly describe the network architecture for a typical 3D UASN, then we review the characteristics of the acoustic channel and the corresponding challenges of it and finally, we discuss about the different layers e.g. MAC protocols, routing protocols, and signal processing for the application layer of UASNs.

A Survey on Real-Time MAC Protocols in Wireless Sensor Networks

As wireless sensor network becomes pervasive, new requirements have been continuously emerged. How-ever, the most of research efforts in wireless sensor network are focused on energy problem since the nodes are usually battery-powered. Among these requirements, real-time communication is one of the big research challenges in wireless sensor networks because most of query messages carry time information. To meet this requirement, recently several real-time medium access control protocols have been proposed for wireless sensor networks in the literature because waiting time to share medium on each node is one of main source for end-to-end delay. In this paper, we first introduce the specific requirement of wireless sensor real-time MAC protocol. Then, a collection of recent wireless sensor real-time MAC protocols are surveyed, classified, and described emphasizing their advantages and disadvantages whenever possible. Finally we present a dis-cussion about the challenges of current wireless sensor real-time MAC protocols in the literature, and show the conclusion in the end.

Media Access with Spatial Reuse for Cooperative Spectrum Sensing

The increasing interest for wireless communication services and scarcity of radio spectrum resources have created the need for a more flexible and efficient usage of the radio frequency bands. Cognitive Radio (CR) emerges as an important trend for a solution to this problem. Spectrum sensing is a crucial function in a CR system. Cooperative spectrum sensing can overcome fading and shadowing effects, and hence increase the reliability of primary user detection. In this paper we consider a system model of a dedicated detect-andforward wireless sensor network (DetF WSN) for cooperative spectrum sensing with k-out-of-n decision fusion in the presence of reporting channels errors. Using this model we consider the design of a spatial reuse media access control (MAC) protocol based on TDMA/OFDMA to resolve conflicts and conserve resources for intra-WSN communication. The influence of the MAC protocol on spectrum sensing performance of the WSN is a key consideration. Two design approaches, using greedy and adaptive simulated annealing (ASA) algorithms, are considered in detail. Performance results assuming a grid network in a Rician fading environment are presented for the two design approaches.

A timeslot assignment scheme for cluster-tree based wireless sensor network

Many efforts have been made to develop time division multiple access (TDMA) slots allocation in amulti-hop converge-cast wireless sensor network (WSN),however,most of them either use complex algorithmor concern frames only without simultaneous transmission in a single slot.In this paper,we presenta timeslot assignment scheme for cluster-tree-based TDMA WSN,covering three frequently used workingmodes in practical applications.The shortest frame formed can guarantee real-time communication and isalso facilitated for message and slot integration,since timeslots allocated to a single node are continuous.During allocation processes,the algorithms are distributed and light-weighted.The experiment resultedfrom a WSN prototype system shows that our scheme can achieve a good reliability.

Efficient Packet Scheduling Technique for Data Merging in Wireless Sensor Networks

Wireless Sensor Networks(WSNs) has become a popular research topic due to its resource constraints. Energy consumption and transmission delay is crucial requirement to be handled to enhance the popularity of WSNs. In order to overcome these issues, we have proposed an Efficient Packet Scheduling Technique for Data Merging in WSNs. Packet scheduling is done by using three levels of priority queue and to reduce the transmission delay. Real-time data packets are placed in high priority queue and Non real-time data packets based on local or remote data are placed on other queues. In this paper, we have used Time Division Multiple Access(TDMA) scheme to efficiently determine the priority of the packet at each level and transmit the data packets from lower level to higher level through intermediate nodes. To reduce the number of transmission, efficient data merge technique is used to merge the data packet in intermediate nodes which has same destination node. Data merge utilize the maximum packet size by appending the merged packets with received packets till the maximum packet size or maximum waiting time is reached. Real-time data packets are directly forwarded to the next node without applying data merge. The performance is evaluated under various metrics like packet delivery ratio, packet drop, energy consumption and delay based on changing the number of nodes and transmission rate. Our results show significant reduction in various performance metrics.

An IEEE 802.15.4 Based Adaptive Communication Protocol in Wireless Sensor Network: Application to Monitoring the Elderly at Home

Monitoring behaviour of the elderly and the disabled living alone has become a major public health problem in our modern societies. Among the various scientific aspects involved in the home monitoring field, we are interested in the study and the proposal of a solution allowing distributed sensor nodes to communicate with each other in an optimal way adapted to the specific application constraints. More precisely, we want to build a wireless network that consists of several short range sensor nodes exchanging data between them according to a communication protocol at MAC (Medium Access Control) level. This protocol must be able to optimize energy consumption, transmission time and loss of information. To achieve this objective, we have analyzed the advantages and the limitations of WSN (Wireless Sensor Network) technologies and communication protocols currently used in relation to the requirements of our application. Then we proposed a deterministic, adaptive and energy saving medium access method based on the IEEE 802.15.4 physical layer and a mesh topology. It ensures the message delivery time with strongly limited collision risk due to the spatial reuse of medium in the two-hop neighbourhood. This proposal was characterized by modelling and simulation using OPNET network simulator. Finally we implemented the proposed mechanisms on hardware devices and deployed a sensors network in real situation to verify the accuracy of the model and evaluate the proposal according to different test configurations.

Robust UAV Aided Data Collection for Energy-Efficient Wireless Sensor Network with Imperfect CSI

Due to its air superiority and high mobility, unmanned aerial vehicle (UAV) can obtain better line-of-sight (LoS) link transmission channel. Therefore, UAV assisted data collection for wireless sensor networks (WSNs) has become an important research direction. This paper intends to minimize the loss of WSNs for the robust data acquisition and communication assisted by UAV under the imperfect channel state information (CSI). On the premise of ensuring the completion of the communication task, we jointly optimize the wake-up schedule of SNs and the flight trajectory of the UAV, by considering the flight speed of the UAV and the sparse access of all sensor nodes (SNs) in WSN. Because the formulated optimization problem is a mixed integer nonconvex problem, we decompose the original problem into the efficient suboptimal solutions to overcome the difficulty of the optimization. Finally, the number of access node corresponding to the optimized operation time and access efficiency is induced for the entire WSN system efficiency improving. The simulation shows the performance gains of our proposed scheme and the influences of the system parameters are analyzed.

REA-MAC:A low latency routing-enhanced asynchronous duty-cycle MAC protocol for wireless sensor networks

Many energy efficiency asynchronous duty-cycle MAC(media access control) protocols have been proposed in recent years.However,in these protocols,wireless sensor nodes almost choose their wakeup time randomly during the operational cycle,which results in the packet delivery latency increased significantly on the multiple hops path.To reduce the packet delivery latency on multi-hop path and energy waste of the sender's idle listening,a new low latency routing-enhanced asynchronous duty-cycle MAC protocol was presented,called REA-MAC.In REA-MAC,each sensor node decided when it waked up to send the beacon based on cross-layer routing information.Furthermore,the sender adaptively waked up based on the relationship between the transmission request time and the wakeup time of its next hop node.The simulation results show that REA-MAC reduces delivery latency by 60% compared to RI-MAC and reduces 8.77% power consumption on average.Under heavy traffic,REA-MAC's throughput is 1.48 times of RI-MAC's.

Hardware/Compiler Memory Protection in Sensor Nodes

With reference to sensor node architectures, we consider the problem of supporting forms of memory protection through a hardware/compiler approach that takes advantage of a low-cost protection circuitry inside the microcontroller, interposed between the processor and the storage devices. Our design effort complies with the stringent limitations existing in these architectures in terms of hardware complexity, available storage and energy consumption. Rather that precluding deliberately harmful programs from producing their effects, our solution is aimed at limiting the spread of programming errors outside the memory scope of the running program. The discussion evaluates the resulting protection environment from a number of salient viewpoints that include the implementation of common protection paradigms, efficiency in the distribution and revocation of access privileges, and the lack of a privileged (kernel) mode.