基于最优阶估计与分布式分簇的传感器网络数据压缩方法研究

在无线传感器网络的诸多应用中,被监测区域发生异常情况的概率通常较小,正常情况下,同一传感器节点在前后连续时刻所采集的数据具有时间相关性,处于相邻区域的不同传感器节点在同一时刻所采集的数据具有空间相关性,发送存在时间、空间冗余的数据至基站必将耗费节点大量的能量。该文提出了基于最优阶估计和分布式分簇的传感器网络数据压缩方法,利用节点采集数据的时空相关性,基于最优阶估计在基站处建立相关系数,经分布式分簇,节点仅需传送少量数据,基站根据时空相关性恢复原始数据。仿真结果表明应用该算法,可以有效减少传感器网络中冗余数据传输量和节点能耗,进而延长系统寿命。     

无线传感器网络中能耗均衡的数据收集算法

无线传感器网络所具有的集中式数据收集、多跳数据传输、多对一流量模式容易导致严重的包碰撞、网络拥塞,包丢失,同样也会导致能量消耗的热点出现,使某些节点甚至整个网络过早死亡.文中提出一种能耗均衡的数据收集算法,此算法按节点离基站的距离进行分层,根据中间节点的能量参数和通信开销建立到基站的多径路由,在数据收集过程中除了利用具有最小能耗的最优路径外还偶尔使用一些次优路径;为进一步减少节点能耗,算法还采用了数据聚合机制.分析和仿真结果表明,算法在很大程度上均衡了节点间能耗并延长了网络寿命.     

一种适用于异步无线传感器网络的机会路由机制

无线传感器网络通常使用低占空比的异步睡眠调度来降低节点能耗。由于发送节点在接收节点醒来后才能向其发送数据,这将引入额外的等待时延。在最近的一些任播路由机制中,发送节点动态地选择最先醒来的候选节点转发数据,以最小化等待时延。但是,由于从最先醒来的候选节点到基站的时延可能并不低,任播路由机制并不一定能最小化端到端总时延。为此,提出了一种适用于异步无线传感器网络的机会路由机制,将路由决策建模为强马尔科夫过程,并根据最优停止理论推导出该过程一种简化的停止规则。仿真结果表明,节点到基站的最大端到端时延仅为基于地理位置的机会路由的68.5%。     

延迟容忍传感器网络中基于移动协助的数据传输

提出了基于移动协助的动态数据传输算法(MAD, movement-assisted adaptive data delivery)。在缓冲区域内设置数据缓存节点,让基站在缓冲区内周期性地移动,数据动态地复制给更有可能到达缓冲区并且剩余能量较高的节点,然后基站在移动中将缓存节点中的数据进行收集。MAD是由数据传输和队列管理2部分组成。前者根据节点的运动趋势和剩余能量计算节点的转发概率,后者通过消息的生存时间和消息的最大复制数确定队列中消息发送的优先级及丢弃方法。仿真结果表明,与其他策略相比,MAD在传输成功率和网络寿命方面具有更好的性能。     

基于最优簇头数和三段路由的改进型LEACH算法

LEACH协议可延长无线传感器网络的使用寿命,提高信息传输量.但是研究发现基站距离网络区域愈远,LEACH协议的效果愈差,网络价值愈小.故本文提出了一种基于最优簇头数和三段路由的改进型LEACH算法,以克服基站位置对网络寿命和信息传输量的影响.该算法依据不同WSN的传感器节点数目,预先计算出理论上最优的簇头数目,残余能量最高的簇头将被选举为唯一的高层簇头,形成节点—簇头—高层簇头—基站的三段数据路由.实验结果表明,与LEACH协议相比,当传输距离小于距离阈值时,该算法有效提升了节点能耗的均衡性,推迟首节点死亡时间,从而提高信息传输量;当距离超过阈值后,网络寿命和信息传输量显著提高,算法优势更为明显.     

C-V2X下车载安全数据两阶段组播的中继选择与功耗分析

车载通信业务的需求加剧了基站功率消耗,降低了其数据传输的可靠性.本文提出了一种蜂窝网络下基于两阶段组播的车载安全数据传输中继选择策略,以节约系统总功耗为前提来确定中继选择范围,计算出基站功耗最小的最优组播半径x₀,并选择距最优组播半径x₀最近的车辆作为中继.基于中继的社会属性建立基站群体和中继群体间的非对称演化博弈模型,设计了不影响安全数据传输的中继娱乐数据发送功率动态再分配的奖惩机制.仿真结果表明：当车辆数目超过临界值K_min时,本文提出的中继选择策略和奖惩机制,可在保证安全数据两阶段组播可靠性的同时,使基站功耗相比直接组播的功耗至少降低25%.     

实时管理约束下节点级低功耗数据融合技术

通过对工业无线传感器网络中传感数据在时间维数据特征的研究,结合网络管理实时性的要求,提出了一种实时管理约束下节点级低功耗数据融合算法.该算法能实现网关对网络的实时管理,是一种有效地进行数据优化和管理的方式.理论分析和实验表明,该算法减少了数据发送的次数,节点的功耗减少了28%,提高了网络生命周期,并节省网络通信带宽.     

一种无线传感器网络拥塞控制机制

无线传感器网络的拥塞会增加网络延迟、降低网络吞吐量、尤其不利于传感器网络的节能。该文提出了一种能量有效的无线传感器网络拥塞控制机制,主要包括逐跳拥塞反馈和速率调节两部分。节点周期性地计算其上游节点发送速率和本地缓冲队列可用空间,并根据一定策略来推测在当前周期内发生拥塞的可能性;拥塞节点的上游节点收到拥塞反馈后根据自身缓冲队列的使用情况来降低速率,此拥塞节点同时向其下游节点申请提高发送速率;基站根据应用要求以闭环方式调节源速率。仿真实验表明,该文的拥塞控制机制不仅能有效地缓解网络拥塞,还保持了网络吞吐量的稳定并具有良好的能源有效性。     

一种基站可移动传感器网络再编程协议

 本文针对基站可移动传感器网络实现了一再编程协议MovPro.该协议可以将新的二进制程序通过多跳的形式下发到网络内的节点上并使之运行.该协议的大致过程描述为,当基站在网络内移动时,基站将数据发送给它移动轨迹上的节点.节点收到部分二进制代码后通过窗口交换的形式将二进制代码传播到整个网络.MovPro是第一个在基站可移动传感器网络的真实系统.本文通过多种方式减少通信开销,并通过二级存储的方式减少外部flash的写次数.实验表明MovPro适用于基站可移动传感器网络.     

无线传感器网络中基于能量的成簇协议

无线传感器网络采用能量有效方式传输数据对于延长传感器网络寿命十分重要。LEACH是一种基于簇的协议,它采用本地簇头随机轮转机制将能量负载均匀分布到网络中的所有传感器节点,簇头节点将收集到数据进行融合后发送给基站。提出一种改进的方案,采用随机成簇算法让网络中传感器节点成簇,成簇的过程考虑传感器节点剩余能量和簇头与非簇头结点之间的距离。通过分析评价和仿真结果,说明新算法比LEACH更能有效利用能量且发送更多的数据。     

Performance Analysis of Transmitter-Side Cooperation–Receiver-Side-Relaying Schemes for Heterogeneous Sensor Networks

In this paper, we present two physical layer cooperative protocols for heterogeneous sensor networks. There is one cooperator near the transmitter and a second cooperator (as a relay) near the receiver. Although the focus is on heterogeneous sensor networks, the methods can be applied to homogeneous sensor networks as well. Analytical and simulation results show that, under an additive white Gaussian noise channel assumption for the links between the transmitter and its partner and between the receiver and its partner, the proposed protocols achieve a diversity order of three or four by using the amplify-and-forward cooperation strategy and maximal ratio combining in the receiver. In addition, the proposed methods outperform the noncooperative single-hop transmission in the clustered heterogeneous sensor network and save a considerable amount of energy relative to the noncooperative transmission.     

Sink Node Placement Strategies for Wireless Sensor Networks

In wireless sensor networks (WSNs), all the data collected by the sensor nodes are forwarded to a sink node. Therefore, the placement of the sink node has a great impact on the energy consumption and lifetime of WSNs. This paper investigates the energy-oriented and lifetime-oriented sink node placement strategies in the single-hop and multiple-hop WSNs, respectively. The energy-oriented strategy considers only the minimizing of the total energy consumption in the networks, while the lifetime-oriented strategy focuses much more on the lifetime of the nodes which consume energy fastest. Using a routing-cost based ant routing algorithm, we evaluate the performances of different placement strategies in the networks. Simulation results show that the networks with lifetime-oriented strategy achieve a significant improvement on network lifetime.     

物联网感知层多路径传输策略研究

多路径数据传输是无线传感器网络亟需解决的一个关键问题.本文针对节点故障、链路失效和外界干扰影响网络稳定性和可靠性,提出一种基于混合蛙跳算法的无线传感器网络多路径传输策略.首先我们详细介绍了蛙跳算法及其原理,之后我们将其应用到无线传感器网络多路径传输策略之中,接着运用混合蛙跳算法对传感网络节点其进行更新、划分、重组以便选择出最优节点建立传输最优路径,提高网络的稳定性和可靠性.通过算法仿真与结果对比提出的算法与AODV、粒子群PSO算法相比,在网络能耗、传输时延、丢包率、连通率和可靠度等方面都具有较好的性能.其中网络能耗比AODV、PSO算法降低了62.5％和35.8％.     

Energy Planning for Progressive Estimation in Multihop Sensor Networks

Multihop sensor networks where transmissions are conducted between neighboring sensors can be more efficient in energy and spectrum than single-hop sensor networks where transmissions are conducted directly between each sensor and a fusion center. With the knowledge of a routing tree from all sensors to a destination node, we present a digital transmission energy planning algorithm as well as an analog transmission energy planning algorithm for progressive estimation in multihop sensor networks. Unlike many iterative consensus-type algorithms, the proposed progressive estimation algorithms along with their transmission energy planning further reduce the network transmission energy while guaranteeing any pre-specified estimation performance at the destination node within a finite time. We also show that digital transmission is more efficient in transmission energy than analog transmission if the available transmission time-bandwidth product for each link and each observation sample is not too limited.     

适于多跳移动Ad Hoc网络的非对称双信道媒质接入控制协议

In order to resolve the hidden and exposed terminal problems and improve the probability of concurrent packet transmissions for multihop Mobile Ad Hoc Networks (MANETs), a novel slotted Asymmetric Dual-Channel Medium Access Control (ADC-MAC) protocol is proposed. It exploits simultaneous reservation with less collisions and collision-free data packet transmissions, and achieves optimal transmission balance on the Control Channel (CCH) and Data Channel (DCH) by adjusting the relationship between Reservation Slot (RS) on the CCH and the data packet Transmission Slot (TS) on the DCH. Transmission interferences can be avoided by only observing CCH for the transmission time of a data packet. The proposed RS and contention micro-slot backoff mechanisms also greatly improve channel access efficiency. Simulation results show that compared to IEEE 802.11 DCF and p-Mc protocols, the proposed protocol can achieve a throughput gain of 88% in single-hop networks and 151% in multihop networks at the same total data rate.     

Energy harvesting,cooperative spectrum sensing,and data transmission improvement in energy‐efficient multichannel cognitive sensor networks

In this paper, we investigate the energy harvesting capability in a multichannel wireless cognitive sensor networks for energy‐efficient cooperative spectrum sensing and data transmission. Spectrum sensors can cooperatively scan the spectrum for available channels, whereas data sensors transmit data to the fusion center (FC) over those channels. We select the sensing, data transmission, and harvesting sensors by setting the sensing time, data transmission time, and also harvesting time to maximize the network data transmission rate and improve the total energy consumption in the multichannel network under global probability of false alarm and global probability of detection constraints. We formulate our optimization problem and employ the convex optimization method to obtain the optimal times and nodes for spectrum sensing, data transmission, and harvesting energy in each subchannel for multiband cognitive sensor networks. Simulation results show that in our proposed algorithm, the network data transmission rate is improved while more energy is saved compared with the baseline methods with equal sensing time in all subchannels.     

基于机会式网络编码的高效广播传输算法

为了提高无线网络广播传输的效率,针对单跳无线网络提出了采用编码方法的广播传输算法。在传统的无线广播传输模型的基础上,分别实现了基于机会式网络编码的单组合分组广播传输算法和多组合分组广播传输算法。它们采用不同的策略选择多个丢失分组编码组合成重传分组,并通过从编码组合数据分组中恢复丢失分组的方式来提高广播传输的吞吐量。仿真结果表明,新算法在不同无线信道传输模型下相比已有的算法有效地降低了广播传输所需的传输带宽。     

Joint power control and rate adaptation in wireless sensor networks

Wireless sensor networks (WSNs) are energy-constrained, as a result, energy allocation and data transmission on sensor nodes are always considered together. However, current approaches ignore the multiple-hop nature of sensor networks, which results in the lack of modeling energy consumption in data relaying process. In this paper, we illustrate the importance of this issue and formulate the data sensing and transmission in WSNs as a network utility maximization (NUM) problem. A price-based distributed algorithm is proposed to solve this NUM problem, and it can stimulate the cooperation of power control and rate adaptation among the nodes along the data relaying path. Considering the time-varying wireless environment in WSNs, the stability of the proposed algorithm is studied by convergence analysis under stochastic perturbations. Numerical results show that the proposed algorithm converges to the optimal energy allocation and data transmission.     

宽带微波被动/红外复合制导数据管理策略研究

多传感器数据管理策略是多模复合制导数据融合的核心问题之一.实际战场环境中传感器数据状态复杂多变,为了充分利用各传感器资源使系统性能达到优化,需要根据不同的数据状态采取相应的管理策略来有效控制和管理这些传感器.提出了基于多传感器实时测量数据状态的数据管理策略问题并分析了其重要性和复杂性.在分析宽带微波被动/红外复合制导数据融合处理流程的基础上进行了数据管理策略的分解和设计.最后通过仿真实验验证了该策略的有效性.     

Filtering strategies for TFC selection schemes in 3GPP W-CDMA systems

The selection of a suitable transport format combination (TFC) according to the system load condition is one important issue of the radio resource management (RRM) in 3GPP W-CDMA systems. Different TFCs specify different ways of transmitting user data input from logical channels. It is observed that data transmission with a higher data rate will suffer a higher bit error rate (BER). This paper investigates the impact of BER on the selection of optimal TFC for transmitting the user data. Two filtering strategies are proposed to filter out infeasible TFCs so that the optimal TFC can be selected to achieve high performance. Moreover, an imbedded Markov chain is developed to evaluate the proposed strategies. From the simulation results, the feasibility and the effectiveness of the proposed strategies are demonstrated as well. We are suggesting that, for the design of an optimal TFC selection algorithm, the proposed TFC filtering strategy shall be taken into consideration.