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1.
The IEEE 802.15.4 specification is a recent low data rate wireless personal area network standard.While basic security services are provided for,there is a lack of more advanced techniques which are indispensable in modern personal area network applications.In addition,performance implications of those services are not known.In this paper,we describe a secure data exchange protocol based on the ZigBee specification and built on top of IEEE 802.15.4 link layer.This protocol includes a key exchange mechanism.We assume that all nodes are applying power management technique based on the constant event sensing reliability required by the coordinator.Power management generates random sleep times by every node which in average fairly distributes the sensing load among the nodes.Key exchange is initiated by a cluster coordinator after some given number of sensing packets have been received by the coordinator.We develop and integrate simulation model of the key exchange and power management technique into the cluster's reliable sensing function.We evaluate the impact of security function and its periodicity on cluster performance.  相似文献   

2.
The use of IEEE 802.15.4 standard based application systems has been rapidly increasing, for example, in medical services, sensor networks, public safety systems, and home automation systems. However, issues arise from the fact that IEEE 802.15.4 standard based low rate wireless personal area networks (LR-WPANs) use the same frequency bands as wireless local area networks (WLANs), and they interfere with each other. Based on past research on this issue, the interference has a more serious impact on LR-WPANs' performance than on WLANs' performance. In this paper we propose a method to improve LR-WPANs' performance while coexisting with WLANs, which is called the reliable beacon transmission based medium access control (MAC) protocol. Since the reliability of a beacon frame is important, in this method, only the beacon frame is transmitted in interference-free channels, and the data packets are transmitted in interfered channels instead of abandoning the channels altogether. This method increases the reliability of beacon frames as well as overall channel utilizations. The effectiveness of the proposed method was evaluated through extensive simulations, and this paper proves that this method improves the performance of IEEE 802.15.4 based wireless sensor networks (WSNs) over WLANs' interferences.  相似文献   

3.
Markov chains are extensively used in modeling different aspects of engineering and scientific systems, such as performance of algorithms and reliability of systems. Different techniques have been developed for analyzing Markovian models, for example, Markov Chain Monte Carlo based simulation, Markov Analyzer, and more recently probabilistic model-checking. However, these techniques either do not guarantee accurate analysis or are not scalable. Higher-order-logic theorem proving is a formal method that has the ability to overcome the above mentioned limitations. However, it is not mature enough to handle all sorts of Markovian models. In this paper, we propose a formalization of Discrete-Time Markov Chain (DTMC) that facilitates formal reasoning about time-homogeneous finite-state discrete-time Markov chain. In particular, we provide a formal verification on some of its important properties, such as joint probabilities, Chapman-Kolmogorov equation, reversibility property, using higher-order logic. To demonstrate the usefulness of our work, we analyze two applications: a simplified binary communication channel and the Automatic Mail Quality Measurement protocol.  相似文献   

4.
In this paper, to solve the consensus control problem of multi-manipulator systems under Markov switching topologies, we propose a distributed consensus control strategy based on disturbance observer. In multi-manipulator systems, external disturbance described by heterogeneous exogenous systems is considered, and all communication topologies are directed. First, a disturbance observer is presented to suppress the influence of unknown external disturbance, and the equivalent compensation is introduced into the control protocol in multi-manipulator systems. Then, a novel control protocol based on neighbor information is designed, which guarantees that multi-manipulator systems reach consensus under Markov switching topologies. Finally, two simulation examples verify the validity of the theoretical result.  相似文献   

5.
In this paper, the stabilization problem is considered for the class of wireless networked control systems (WNCS). An indicator is introduced in the WNCS model. The packet drop sequences in the indicator are represented as states of a Markov chain. A new discrete Markov switching system model integrating 802.11 protocol and new scheduling approach for wireless networks with control systems are constructed. The variable controller can be obtained easily by solving the linear matrix inequality (LMI) with the use of the Matlab toolbox. Both the known and unknown dropout probabilities are considered. Finally, a simulation is given to show the feasibility of the proposed method.  相似文献   

6.
The previously known frameworks describing the consistency of support vector machine classification(SVMC) algorithm are usually based on the assumption of independent and identically distributed(i.i.d.) samples.In this paper we go far beyond these classical frameworks by studying the consistency of SVMC algorithm with uniformly ergodic Markov chain samples based on linear prediction models.We establish the bound on the consistency of SVMC algorithm with uniformly ergodic Markov chain samples,and show that SVMC algorithm with uniformly ergodic Markov chain samples is consistent.Inspired by the idea from Markov chain Monto Carlo(MCMC) methods,we introduce a new Markov sampling algorithm for classification to generate uniformly ergodic Markov chain samples from large data set,and present numerical studies on simulated data and benchmark repository using SVMC algorithm.  相似文献   

7.
A new formal method for communication protocol specification is presented.FSM,CSP and ADT are mixed and the best features of these approaches can be offered in the fomal method.First,we briefly describe the formal techniques of communication protocol.We then put forward the hybrid method of protocol specification.Finally,an example,i.e.,IEEE 802.3 MAC protocol for LAN described by the proposed formal method,is given.The results of studies show that this hybrid formal method for protocol specification is a correct,unambiguous and complete approach.  相似文献   

8.
In this paper, the average packet delay on IEEE 802.11 DCF under finite load traffic in multi-hop ad hoc networks is analyzed. We employ a Markov chain model to analyze the probability of transmission at each node in an arbitrary slot and derive the channel access delay. We model each node using an M/G/1 queue and derive the queueing delay. The model is extended from analyzing the single-hop average packet delay to evaluating the end-to-end packet delay in multi-hop ad hoc networks without assuming the traffic to be in a saturation state. To validate our analytic results, we have done extensive simulation. The analytic and the simulation results match very well.  相似文献   

9.
In recent years, Extensible Messaging and Presence Protocol (XMPP) is gaining momentum in Internet of Things (IoT). It has been widely used in chatting, message exchanging and unique addressing. As a matter of course, it raises an interesting issue: how to formally test the conformance and performance of XMPP in IoT environment. While conformance testing of communicating protocols is a functional test that verifies whether the behaviors of the protocol satisfy defined requirements, performance testing is a qualitative and quantitative test that aims at checking whether the performance requirements of the protocol are satisfied under certain conditions. In this paper, we present a logic-based passive testing approach that can test both the conformance and the performance of XMPP protocol through real execution traces and formally specified properties. To evaluate and assess our methodology, we present a developed prototype and the experiments with a set of XMPP properties. Finally, the relevant verdicts and conclusions are provided.  相似文献   

10.
A continuous-rime finite-state Markov chain observed in white noise is considered. The well-known result of Wonham filter provides a formula for obtaining posterior probabilities. Although the filter is of finite dimension, numerical schemes are needed in applications because of the nonlinearity and because the observations are frequently collected in discrete moments. In this work, we develop approximation schemes of Wonham filters by constructing discrete-time recursive algorithms. We prove the convergence of the algorithm by weak convergence method and martingale averaging techniques. Numerical experiments are also famished to demonstrate the performance of our algorithms.  相似文献   

11.
非时隙CSMA/CA性能分析与研究   总被引:2,自引:0,他引:2       下载免费PDF全文
通过对基于IEEE802.15.4的无线传感网络的非时隙CSMA/CA的算法进行分析,建立了适合于大部分无线传感网络实际应用的具有单步转移概率分布的离散马尔可夫链模型。并给出了在该模型下数据包延时、退避次数两个主要的网络性能评价指标的计算公式。最后通过仿真实验分析了CSMA/CA算法的三个网络参数对系统性能的影响。  相似文献   

12.
为了优化802.15.4 MAC协议能耗性能,提出了一种基于退避时提前休眠的时隙CSMA/CA机制,并建立了该协议的Markov链模型。然后使用M/G/1排队系统理论对非饱和网络负载建模,并对协议主要参数进行了数学推导。最后基于该模型对网络节点能耗进行数值分析。理论分析和仿真结果表明,该模型较好的描述基于非饱和负载的802.15.4 MAC协议,网络节点能耗得到有效改善。  相似文献   

13.
非饱和状态下时隙CSMA/CA机制改进与性能分析   总被引:1,自引:0,他引:1       下载免费PDF全文
针对无线传感器网络中有重要信息的高优先级数据包需要尽快传输,且IEEE802.15.4协议本身不支持任何优先级机制的情况,结合优先级调度策略和差分服务机制,对具有优先级级的时隙CSMA/CA机制进行全面数学建模,包括节点马尔科夫模型和信道马尔科夫模型,据此提出了一种非饱和状态下具有优先级的IEEE802.15.4时隙CSMA/CA机制性能的分析方法。通过比较分析,改进的机制对提高网络中高优先级数据包的传输性能具有积极作用。  相似文献   

14.
针对IEEE 802.15.4时隙载波侦听多址接入与碰撞避免(CSMA/CA)算法,利用二维Markov链分析方法提出了一个网络分析模型。该模型特别考虑了IEEE 802.15.4协议的休眠模式以及退避窗口先于退避阶数(NB)达到最大值的情况。在此基础上,结合M/G/1/K排队理论推导得到了吞吐量的表达式,进而分析了网络在非饱和状态下数据包到达率对吞吐量的影响,利用模拟平台NS2进行了仿真。实验结果显示理论分析结果与仿真结果可以较好地拟合,并能准确描述网络吞吐量的变化,验证了分析模型的有效性。  相似文献   

15.
802.15.4协议中CSMA/CA信道接入方式为了避免再次碰撞使用BEB退避算法,在重负载的情况下网络性能较差。提出一种自适应的退避算法,它用报文的冲突概率来预测节点附近信道的争用状况,在不同的网络状况下,竞争窗口的取值采用相应的退避策略,动态地控制节点的退避范围,以达到改善网络性能的目的。分析与仿真结果表明,新的算法与传统的退避算法BEB算法相比,在网络负载重的情况下,有效地降低了数据包的冲突概率,减少了时延,提高了网络的吞吐量,同时对信道的公平性也有所改善。  相似文献   

16.
乔冠华  毛剑琳  郭宁  陈波  戴宁  张传龙 《计算机应用》2013,33(10):2723-2725
考虑节点移动且数据传输率不断变化对网络性能的影响,针对IEEE802.15.4提出了一种网络负荷概率判断和指数加权滑动平均(PJNL_EWMA) 的退避策略,在每次载波监听多路访问/冲突避免(CSMA/CA)算法开始时采用网络负荷概率判断思想判定当前网络状况,然后通过指数加权滑动平均方法动态地调整退避指数。通过NS2的仿真结果表明:与IEEE802.15.4标准协议算法及MBS+EWMA算法相比,PJNL_EWMA算法不仅提高了网络吞吐量,同时还减小了数据包的丢包率和碰撞概率,提高了网络性能。  相似文献   

17.
黄亮  王福豹  马超  杨晗 《计算机应用》2013,33(10):2726-2729
基于非时隙CSMA/CA随机接入机制的IEEE802.15.4MAC协议组网耗时过长,不能满足自组网实时通信应用需求。针对这一问题,分析了MAC组网流程中各步骤所耗时间,提出一种新的快速组网策略,采用预分配信道,将关联过程从间接传输简化为直接传输,改进CSMA/CA冲突避免机制以减少冲突。仿真实验和现场测试结果均表明,与IEEE 802.15.4协议相比,提出的快速组网策略使得信道冲突降低,组网时间更快,更符合实时通信需求。  相似文献   

18.
基于模糊逻辑的多速率WLAN自适应MAC协议   总被引:1,自引:0,他引:1  
段中兴  张德运 《计算机工程》2006,32(3):113-115,121
针对DCF应用在多速率无线局域网中存在吞吐量异常和严重不公平性问题,提出了一个基于信道状态和节点速率的模糊自适应退避算法——RCFAB算法。仿真结果表明,RCFAB能够适应多速率WLAN,并有效地改善系统的吞吐量和接入公平性。  相似文献   

19.
IEEE802.15.4标准是为满足低速率、低能耗、低成本需求而制定的无线个人区域网(LR_WPAN)规范。通过用网络仿真软件NS2对基于IEEE802.15.4的无线传感器网络的主要性能指标进行分析,较为详实地论述了IEEE802.15.4MAC层基于时槽的CSMA/CA机制,最后给出仿真环境及其结果,并进行度量分析和阐述各指标间的依赖关系。  相似文献   

20.
The study deals with the analysis of latency introduced by the media access control algorithm of LonTalk protocol registered as ANSI/CEA-709.1 standard and used in LonWorks control networking technology. The LonTalk protocol provides multicast communication which is a distinctive feature among control network protocols. The predictive p-persistent CSMA protocol built in the MAC sublayer uses the memoryless backoff, additive increase/additive decrease contention window adjustments, provides collision avoidance and optional collision detection.The behavior of the LonTalk MAC protocol, unlike of the other CSMA schemes, is forced not only by the traffic rate but also by the structure of the workload transmitted through the channel. Therefore, the predictive p-persistent CSMA performance depends on the load scenario defined as the specification of the input traffic generated to the network. In the study, a unified method of load scenario definition integrating various addressing and message service types, is used. The contribution of the paper is the adaptation of the analytical approach based on Markov chains to the evaluation of mean access delay of LonTalk protocol for any load scenario.  相似文献   

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