移动网络路由优化解决方案研究

移动网络基本协议允许一组共同运动的通信节点作为一个整体网络连接到互联网,但该协议没有考虑路由优化。本文在移动网络协议的基础上,提出了一种优化方案,既改善了移动网络协议的路由,又解决了移动网络快速切换与路由优化之间的矛盾。     

无线Mesh网络恢复方案的一种通用替代路径算法

为了在WMN（wireless Mesh Network）网络中找到一个普适的常用恢复方案的替代路径查找算法,本文选取了 MANET网中的一种源路由算法DSR为基本恢复算法,并结合了节点的路由缓存功能,论证了一种新的通用替代路径查找的方法,使WMN网络通信中断时能及时恢复,而不用关心中断链路的位置.性能分析表明该机制为WMN网络通信保障有一定的适用性.     

相对位置多次变化的自组织网路由模型仿真

移动自组网络通信过程中,通信节点会根据通信区域的不同发生变化,各个节点之间位置也发生相对移动。造成通信不稳定。为了避免上述传统算法的缺陷,提出基于考虑相对位置变换误差的自组网络路由模型。对移动的通信节点进行模糊性距离分区处理,对不同区域移动通信过程进行分层约束,在建立不同层之间的通信联系,对不同模糊区域内的移动节点进行通信优化处理。实验结果表明,利用该算法进行节点移动过程中的通信路由协议优化处理,能够极大地提高通信的效率,降低通信的误码率,从而满足实际移动自组网络的通信需求。     

基于链路不对称性预测的机会网络路由设计

机会网络的混合路由优化设计可以有效降低冗余开销,提高数据传递成功率。传统方法采用链路代价评估和能量节省延迟容忍算法实现机会网络的路由设计,当在移动自组织网络中出现节点稀疏化调度下链路具有不对称性,降低了路由分配质量。提出一种基于改进的OLSRv2算法的链路不对称性预测控制机会网络混合路由优化算法,定义机会网络中混合置信因子概念,研究路由优化检验统计量的确定和判别系统的设计,通过OLSRv2算法引入了概率路由,在当前连通域的路由信息进行地址压缩得到最优传送概率值。仿真实验表明,采用该算法设计的机会网络路由进行网络通信,得到较小的控制开销,提高通信成功率,网络负载大幅降低。     

基于IEEE 802.11的Ad Hoc网络中的一种节能路由改进算法*

根据IEEE 802.11协议在链路层提供有限次数链路重传的特点,提出了一种在基于IEEE 802.11的移动Ad Hoc网络（MANET）中保证可靠通信的节能路由改进算法——ERRC（Energy-efficient Routing algorithm for Reliable Communication in IEEE 802.11-based MANET）,它可以方便地应用于MANET中现有的反应式路由协议。ERRC分析并建立了适合于IEEE 802.11情况的重传模型和能耗模型,提供了在发送数据分组时的功率控制机制,在节点选路时综合考虑了分组错误概率、节点代价函数的影响。仿真结果表明,ERRC算法可以显著提高网络生存期,在节省能耗方面比没有考虑分组错误概率的节能路由算法更为精确。     

基于断点损耗预测的高速网络流路由修复方法

设计高速网络流路由修复算法,提高网络的生命周期,降低路由节点能耗。传统的路由修复算法采用阈值分割路由冲突分解算法,采用阈值分割判断实现路由修复,无法有效满足高速网络流路由修复的应用环境。提出一种基于断点损耗预测的高速网络流路由修复方法。计算通信节点的衰减性能,绘制出符合高速移动环境移动节点衰减曲线,根据欧氏距离公式计算出随机分布的路由节点的路径链接的稳定性,对多角度系数进行修订,采用断点损耗预测方法,进行功耗损失修订,实现路由修复。仿真实验表明,该算法实现高速网络流路由修复。有效地控制簇头的数量和分布、节约能量、均衡网络负载,提高了高速网络流路由的生命周期,单个节点能耗大幅降低,在高速移动大规模网络流维护和路由控制优化中具有较好的应用价值。     

物联网无线传感器能耗优化SIFT算法的研究

针对目前物联网系统中无线传感器网络在传播信息时能耗损失严重的问题,本文提出了一种应用于物联网无线传感器的改进SIFT算法。该算法基于传统SIFT算法,并在其基础上,进行了节点端自适应优化和全局性动态调整的优化方案。通过参考路由层和应用层信息确定节点的优先级,修正节点的退让长度,实现重要数据先行;通过对接人节点数目和数据流的统计,实现对参数组和信道竞争窗口长度的全局性动态调整。实验表明,本文提出的改进算法在能耗上比传统算法优秀,值得推广使用。     

基于路由热点循迹修正的WSN发射功率优化调度

无线传感器网络WSN发射功率的优化调度是决定WSN使用寿命和提高WSN性能的关键,WSN路由节点的在进行数据转发时会导致热点随机扩散,发射功率无法难以实现最大化。提出一种基于路由热点循迹修正的WSN发射功率调度算法。设计了WSN节点路由热点循迹数据传输模型,对发射功率消耗能量模型采用一个高斯衰减信道建模,采用直线反馈线性化补偿方式对路由热点的偏移轨迹进行超负荷状态评估,采用贪婪算法生成一条多分簇路由链,对路由循迹轨迹进行修正,得到WSN优化发射功率的调度递推公式,实现能耗最佳的功率优化调度。实验结果表明,采用该优化调度方法,在准确实现热点循迹修正,传输功率较传统方法稳定,波动较小,WSN可靠性和生存性增强。     

DTN中基于ACK机制的改进的多副本路由算法

针对DTN中基于多副本的路由算法中存在网络开销和存储开销严重,导致算法的性能受到抑制等问题,提出一种基于ACK机制的改进的多副本路由算法（IAER算法）。该算法中,接收节点通过发送ACK消息来有效地管理节点缓存。此外,根据计数器的值和生成时间来对消息的发送顺序进行优化。通过ONE仿真软件对IAER算法进行仿真验证。理论分析和仿真结果表明,IAER算法能够在保证消息投递率的条件下,显著减少网络开销和存储开销等。     

一种分簇的无线传感器网络数据分发机制仿真

移动sink可以延长无线传感器网络的寿命,开满足一些特定应用的需求.文中提出了一种不依赖于节点地理位置的基于分簇的移动Sink路由算法,源节点和移动sink之间的通信分为簇内通信和簇间通信两部分,因为sink的移动而造成的通信路径的中断被限制在簇内通信.大量仿真显示,在数据的时延,节点的平均能耗和数据的成功接收率方面,该算法的性能远远超过其他移动路由算法.     

移动无线网相邻节点间匿名通信策略

由于移动无线网相邻节点间通信的匿名安全性未被专门而全面地研究,因此提出一种新型移动无线网相邻节点间匿名通信策略是有必要的。首先采用信息签名算法设计了广播式匿名认证方案;其次基于节点伪名设计了任意相邻节点间非交互的一对多密钥共享方案;最后采用Bloom filter隐藏消息接收者,并对算法的匿名性与通信效率进行了分析。     

Quality of Service provisioning for UMTS network users with immediate and advance radio resource reservations

Wideband code division multiple access (WCDMA) is selected as the air interface scheme for 3G wireless networks. This scheme offers a high data rate that makes the wireless networks a suitable environment for real-time packet data services. 3G networks can be used to deliver multimedia traffic with guaranteed quality of service, but faces the scalability challenge in terms of the number of connections that can be setup in the cellular network. The more connections take place in WCDMA based network, the more interference is created, which yields more QoS degradation. To handle this issue, several algorithms that are collectively alleviate the QoS degradation have been developed and implemented. In this paper, we provide a system link simulator that models the WCDMA cellular network with the necessary radio resource management algorithms. The downlink direction has been simulated as it is usually the limiting link in setting up multimedia sessions, and interactive web sessions. The simulation environment provides, through the implementation of new wrap-around technique, a fair source of intra-cell and inter-cell interference, and avoids session disconnections due to the limited simulation area. Then, we suggest an admission control algorithm for admitting immediate and advance radio resource reservation requests. The admission control algorithm decision is based on the amount of interference that the new request will add to the network. The algorithm relies on the radio resource reservation states that stores all admitted immediate and advance sessions.     

Multi-postpath-based lookahead multiconstraint QoS routing

Multiconstraint QoS (quality of service) routing is an essential mechanism for QoS-guaranteed services. Unfortunately, the multiconstraint QoS routing problem is NP-complete. In this paper, we propose a heuristic multiconstraint QoS routing scheme, MPLMR (multi-postpath-based lookahead multiconstraint routing). MPLMR is a routing scheme using an extended shortest-path algorithm. As in previous schemes such as TAMCRA and H_MCOP, MPLMR stores a limited number of subpaths between the source node and each intermediate node, and extends these subpaths toward the destination node. However, MPLMR uses an improved “lookahead” method to estimate the path length of the full path to which each subpath is extended. MPLMR then selects and stores the subpaths that have higher likelihood than other subpaths to be extended to feasible paths. We show via simulation that MPLMR has a smaller probability of missing a feasible path than competing schemes in the literature.     

一种广义预测隐式算法的仿真分析

广义预测控制作为一种随着自适应控制的研究而发展起来的预测控制方法,具有柔化作用,多步预测,滚动优化和在线自适应校正等优点。修正算法有多种,大体上可分为显示算法和隐式算法,文章介绍了一种广义预测隐式自校正控制算法,并对其进行仿真分析。总结主要参数的改变对整个系统性能的影响。结果表明,此算法具有优越型和可行性。     

An improved PSP scheme using state cooperation for phase synchronization

The conventional per-survivor-processing (PSP) scheme suffers from the error propagation problem because it does not fully use the state message provided by a hidden Markov process. This study proposes a vertical cooperation among states to enhance the estimate reliabilities in the PSP scheme. The key idea of the proposed algorithm is to estimate the system uncertainty at each time stage in a maximum likelihood (ML) manner that chooses the parameter estimate of the state with the minimum cumulative branch metric as the survival estimate of the time stage. Computer simulations show that with the improved phase estimates, the proposed algorithm significantly outperforms the conventional PSP scheme in data decoding.     

一种新的定压边界处理方法

依据SIMPLE算法中边界压力的外推格式,结合定压边界条件重新推导了邻近边界内节点的压力计算公式.根据NEUMANN特性给出了新的定压边界速度计算公式,用IDEAL算法来处理压力和速度的耦合.讨论了定压边界流动传热问题的求解步骤.通过几个经典算例将本方法与文献方法进行了对比,结果表明本方法提高了定压边界问题数值解的精度,加快了迭代过程的收敛.     

WiMAX Mesh网络下具有QoS保障的动态握手方案

WiMAX Mesh网络中的3步握手时间影响数据包的延迟和带宽请求次数.固定3步握手参数会给网络带来扩展性问题,且不利于满足用户不同的QoS需求.针对上述问题提出具有QoS保障的动态握手参数调整方案QoSDx,综合节点自身和2跳邻居节点的数量、优先级和3步握手参数等动态调整节点的握手时间.仿真实验表明,QoSDx在不同规模网络下均能提高网络总体性能.IEEE 802.16标准中定义的4种业务流的吞吐率平均提升10%左右.     

基于遗传算法的PID控制器参数优化研究

针对PID控制器在不同的应用系统,需要动态调整PID控制参数的问题,提出了基于遗传算法的PID自适应参数优化方案。该方案通过将PID控制器产生的误差作为目标函数,利用遗传算法实现对PID控制器参数的自动调整。为了提高参数的优化效率,文章通过对交叉算子和变异算子的自适应处理,提高了PID控制器的性能。实验测试表明,文章设计的PID参数优化策略比普通的基于遗传算法优化策略效率平均高14.7%。     

Robust identification of Wiener time-delay system with expectation-maximization algorithm

This paper considers the parameter estimation for Wiener time-delay systems with the output data contaminated with outliers. The time-delay and corrupted output data bring great challenges to the parameter estimation problem. The statistical model of the estimation problem is constructed based on the Laplace distribution and the identification problem is formulated in the scheme of the expectation-maximization (EM) algorithm. The negative effect of outliers imposed on the parameter estimation problem is sufficiently suppressed and the unknown time-delay and model parameters can be estimated simultaneously. The simulation example is given to demonstrate the effectiveness of the proposed algorithm.     

Optimal actuator switching synthesis of observer-based event-triggered state feedback control for distributed parameter systems

The study aims to explore the optimal actuator switching scheme of observer-based event-triggered state feedback control for distributed parameter systems. The performance of distributed parameter systems is improved through the observer-based event-triggered control, in which the state feedback is updated only when a triggered event happens. In such an event-triggered mechanism, the event-based closed-loop system and minimum time interval between consecutive events are bounded. Based on finite horizon linear quadratic regulator (LQR) optimal control, the optimal switching algorithm is proposed based on the event-triggered mechanism during an unfixed time interval. Finally, the proposed scheme is verified through a simulation case.