基于PID算法的无线传感器网络传输功率控制研究

降低能耗是无线传感器网络研究中重要内容之一.节点间数据传输能耗很大,合理调节传输功率,对降低网络能耗非常重要.本文引入PID算法,通过调节每个节点传输功率,动态控制整个网络的传输能耗.MATLAB仿真结果显示,该算法在几种不同的部署情况下,比LMA(local mean algorithm)及其它几种方法在网络启动能耗和启动时耗指标下都更为有效.     

传感器网络中基于网格的功率控制算法

针对无线传感器网络中的“热区”问题,将网络监控区域划分成宽度不等的网格,提出一种基于网格的功率控制算法。通过分析节点的能量消耗计算每层网格的宽度和节点的传输半径,以达到网络能耗的均衡分布。仿真实验结果表明,该算法在能耗均衡方面优于同类算法。     

Performance evaluation of MAC transmission power control in wireless sensor networks

In this paper we provide a method to analytically compute the energy saving provided by the use of transmission power control (TPC) at the MAC layer in wireless sensor networks (WSN). We consider a classical TPC mechanism: data packets are transmitted with the minimum power required to achieve a given packet error probability, whereas the additional MAC control packets are transmitted with the nominal (maximum) power. This scheme has been chosen because it does not modify the network topology, since control packet transmission range does not change. This property also allows us to analytically compute the expected energy savings. Besides, this type of TPC can be implemented in the current sensor hardware, and it can be directly applied to several MAC protocols already proposed for WSN. The foundation of our analysis is the evaluation of L ratio, defined as the total energy consumed by the network using the original MAC protocol divided by the total energy consumed if the TPC mechanism is employed. In the L computation we emphasize the basic properties of sensor networks. Namely, the savings are calculated for a network that is active for a very long time, and where the number of sensors is supposed to be very large. The nodes position is assumed to be random – a normal bivariate distribution is assumed in the paper – and no node mobility is considered. In the analysis we stress the radio propagation and the distribution of the nodes in the network, which will ultimately determine the performance of the TPC. Under these conditions we compute the mean value of L. Finally, we have applied the method to evaluate the benefits of TPC for TDMA and CSMA with two representative protocols, L-MAC and S-MAC using their implementation reference parameters. The conclusion is that, while S-MAC does not achieve a significant improvement, L-MAC may reach energy savings up to 10–20%.     

单节点的无线传感器网络数据传输优化策略

为了提高无线传感器网络（WSNs）节点能量的利用率,延长WSNs的生存时间,提出了一种单节点的WSNs数据传输优化策略.首先对WSNs结构进行分析,并建立单个传感器节点数据传输优化的数学模型;然后采用惩罚函数法对数据传输过程中的传感器节点能耗进行优化;最后在Matlab 2012平台对其进行仿真分析.结果表明：该方法可以根据环境能量的变化对传感器节点能耗进行自适应优化,提高了节点的累积数据传输总量,可以较好适应环境能量不确定性.     

基于WSNs的医院环境监测系统设计

针对传统医院环境监测系统现场布线难、设备移动性差、测量精度不高的问题,提出了一种基于无线传感器网络( WSNs)技术的医院环境监测系统,并详细介绍了该系统的结构、通信机制及软件实现流程.系统由无线传感器节点依据无线通信机制形成WSNs.在分析影响WSNs能耗的主要因素和现有节能技术基础上,提出了一种基于能量均衡的数据可靠传输算法,即动态能量管理分簇算法( DPMCA),该算法把DPM技术和CA有效结合,有效解决了传统医院环境监测系统中存在的问题.     

Transmission power and data rate aware routing on wireless networks

Wireless networks can vary both the transmission power and modulation of links. Existing routing protocols do not take transmission power control (TPC) and modulation adaptation (also known as rate adaptation – RA) into account at the same time, even though the performance of wireless networks can be significantly improved when routing algorithms use link characteristics to build their routes. This article proposes and evaluates extensions to routing protocols to cope with TPC and RA. The enhancements can be applied to any link state or distance vector routing protocols. An evaluation considering node density, node mobility and link error show that TPC- and RA-aware routing algorithms improve the average latency and the end-to-end throughput, while consuming less energy than traditional protocols.     

Autoregressive energy-efficient context forwarding in wireless sensor networks for pervasive healthcare systems

Driven by technological advances in low-power network systems and medical sensors, we have witnessed during the recent years the adoption of wireless sensor networks (WSNs) in electronic healthcare. Improving the quality of electronic healthcare and the prospects of ‘ageing in place’ through WSNs requires solving difficult problems in scale, energy management, and data acquisition. Medical and pervasive healthcare application (or mobile healthcare application) based on WSNs is influenced by many factors such as transmission errors and power consumption. We propose a multivariate context forwarding model that achieves energy-efficient WSN operation. A node adopts multivariate autoregression for forecasting contextual information (bio-signals or vital parameters) and locally decides whether context retransmission is required or not. This scheme is applied in patient telemonitoring systems where accurate yet energy-aware transmission of bio-signals to a remote control unit is crucial. Simulation results are reported indicating the capability of the proposed model in minimizing energy consumption in WSNs having as application domain the electronic healthcare systems.     

A comparative study on popular MAC protocols for mixed Wireless Sensor Networks: From implementation viewpoint

Sensors cooperate and coordinate with each other to disseminate sensed data in the network. In establishing coordination among sensors such that they can access the shared wireless medium, Medium Access Control (MAC) protocol plays an important role. In this article, we presented an analytical study on some popular MAC protocols for Wireless Sensor Networks (WSNs). Based on the design techniques, MAC protocols for WSNs are classified into two main categories: single-layer and cross-layer. MAC protocols such as S-MAC, T-MAC, B-MAC and X-MAC are selected to study the design approaches of single-layer genre. BoX-MAC-1 and BoX-MAC-2 are selected to analyze cross-layer design approaches. This survey paper aims at reporting an implementation viewpoint of different design approaches of MAC protocols in WSN. We have considered mixed WSNs that exhibits node movement (e.g., static, mobile) and changes in communication medium (e.g., air, water). Representative protocols are implemented in Castalia simulator and evaluated on the basis of important performance metrics such as energy consumption, network lifetime, throughput and end-to-end delay. The merits and demerits of different protocols are also compared.     

一种能量高效的无线传感器网络拓扑控制算法

通过对现有拓扑控制算法的研究,针对无线传感器网络中节点能耗分布不均匀的问题,提出了一种能量高效的拓扑控制算法(EETCA)。该算法以均衡全局能耗为目标,综合考虑了节点的剩余能量、簇的规模、数据最优传输跳数等因素,避免了部分节点能量消耗过快,从而有效地均衡网络负载。仿真结果表明:EETCA在能耗均衡方面均优于原来的算法,延长了无线传感器网络的生命周期。     

基于非线性电池模型的WSNs节能技术研究

在无线传感器网络（WSNs）节能技术研究中,如何最大化节点电池能量效率从而延长整个网络寿命是一个关键问题。采用非线性电池模型,使用在低数据传输速率场合中较为节能的FSK调制技术,通过理论分析和参数优化方法,以电池能耗最小为目标,建立电池能耗模型,优化调制指数,使得电池能耗最低。仿真结果表明：该模型能够更加准确地评估节点能耗和寿命。在给定传输距离下,存在一个最优调制指数,使得电池能耗最低。最后给出了不同传输距离对应的最优调制指数。     

无线传感器网络分簇路由节能研究

在大规模传感和环境监测中,节约能源延长传感器节点生命已成为无线传感器网络最重要的研究课题之一。提供合理的能源消耗和改善无线网络生命周期的传感器网络系统,必须设计一种新的有效的节能方案和节能路由体系。方案采用一种聚类算法减少无线传感器网络的能量消耗,创建一种cluster-tree分簇路由结构的传感器网络。该方案主要目标是做一个理想的分簇分配,减少传感器节点之间的数据传输距离,降低传感器节点能源消耗,延长寿命。实验结果表明,该方案有效地降低了能源消耗从而延长无线传感器网络生命。     

An asynchronous scheduled MAC protocol for wireless sensor networks

Wireless sensor networks (WSNs) comprise a number of autonomous sensors and one or more sinks to cooperatively monitor physical or environmental conditions. Energy efficiency is a key design factor of a MAC protocol for WSNs. Due to the importance of the problem, a number of energy efficient MAC protocols have been developed for WSNs. Preamble-sampling based MAC protocols (e.g., B-MAC and X-MAC) have overheads due to their preambles, and are inefficient at large wakeup intervals. SCP-MAC, a synchronous scheduled energy-efficient scheduling MAC protocol, minimizes the preamble by combining preamble sampling and scheduling techniques; however, it does not prevent energy loss due to overhearing; in addition, due to its synchronization procedure, it results in increased contention and delay. In this paper, we present an energy efficient MAC protocol for WSNs that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. We provide an energy consumption analysis for multi-hop networks. To validate our design and analysis, we implement the proposed scheme in TinyOS. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with existing energy efficient MAC protocols.     

基于事件驱动保持网络连通性的WSNs路由协议

为保证无线传感器网络（ WSNs）的连通性,延长网络有效工作期,提出了一种事件驱动成簇、能量高效均衡的路由协议。该协议避免了与事件无关的节点参与成簇而消耗能量,通过簇首选举的控制消息延时转发节省了网络能量,建立了综合考虑当前节点剩余能量和包含其邻居节点的平均剩余能量、当前节点到邻居节点和Sink节点距离的中继路由法则。仿真结果表明：与采用预成簇的AEEC协议和事件驱动成簇的ARPEES协议相比,所提出的路由协议推迟了首个死亡节点的出现时间,使WSNs有效工作期分别提高了4.3倍和47%。     

用于传感网功率控制的并行传输MAC 协议

针对无线传感网（WSNs）中节点间不对称的发射功率引起的隐藏节点和暴露节点问题,提出一种用于传感网功率控制的MAC协议（MAC4PC）.该协议采用邻节点向量表对邻节点的状态及当前会话的信息进行记录,并设计了相关的控制帧收发时序和干扰度判断准则,以保证新建立会话与当前会话互不干涉,从而实现暴露节点的并行传输.仿真结果表明,与802.11 DCF协议、SB-FSMA/CA协议以及GLPCB-PMAC协议相比较,MAC4PC协议提高了网络平均吞吐量,降低了节点平均能耗和数据分组的平均传输时延.     

An efficient power control scheme and joint adaptive modulation for wireless sensor networks

This paper considers wireless sensor networks (WSNs) and quantitatively rates energy efficiency obtained by combining adaptive power/rate control with adaptive modulation scheduling. For multi-access wireless sensor networks, adaptive modulation and power control are two important means to increase spectral efficiency. An adaptive modulation with power control scheme (AM with PC) which mainly reduces power consumption to achieve energy efficiency for wireless sensor networks is proposed in this paper. Cluster head node of each link adaptively adjusts its power control level and modulation type according to the signal to noise ratio (SNR) and target bit error rate (BER). The efficiency of this approach is further illustrated via numerical comparison with the original AM with PC. Simulation results demonstrate that the proposed scheme, which alleviates to save much transmission power and maintains the target bit error rate, can significantly improve the system performance.     

Energy Optimization under Informed Mobility

Energy optimization is important in wireless ad hoc networks, where node battery power is usually limited. Research results show that such a network can exploit controlled node mobility to reduce communication-related energy consumption. However, node movement itself usually consumes energy. In this paper we study the energy optimization problem that accounts for energy costs associated with both communication and physical node movement. We refer to this model as informed mobility. We first review the theoretical foundations on how to reduce total communication energy consumption, as well as increase system lifetime, by combining node movement and transmission power adaptation. Next, we describe and analyze the informed mobility optimization problem. Based on this analysis, we introduce localized algorithms and protocols for informed mobility. We propose iMobif, a flow-based informed mobility framework that collects network information for mobility decision making. We demonstrate how to use iMobif to minimize total communication energy consumption as well as to maximize system lifetime. We compare the performance of iMobif to that of systems with no mobility or only cost-unaware mobility. Simulation results show iMobif is effective in reducing energy consumption relative to such systems.     

Energy-aware node placement,topology control and MAC scheduling for wireless sensor networks

In the WSNs, the nodes closer to the sink node have heavier traffic load for packet forwarding because they do not only collect data within their sensing range but also relay data for nodes further away. The unbalanced power consumption among sensor nodes may cause network partition. This paper proposes efficient node placement, topology control, and MAC scheduling protocols to prolong the sensor network lifetime, balance the power consumption of sensor nodes, and avoid collision. Firstly, a virtual tree topology is constructed based on Grid-based WSNs. Then two node-placement techniques, namely Distance-based and Density-based deployment schemes, are proposed to balance the power consumption of sensor nodes. Finally, a collision-free MAC scheduling protocol is proposed to prevent the packet transmissions from collision. In addition, extension of the proposed protocols are made from a Grid-based WSN to a randomly deployed WSN, enabling the developed energy-balanced schemes to be generally applied to randomly deployed WSNs. Simulation results reveal that the developed protocols can efficiently balance each sensor node’s power consumption and prolong the network lifetime in both Grid-based and randomly deployed WSNs.     

无线传感器网络分簇拓扑控制算法

通过对经典的分簇算法HEED和EEUC进行研究与分析,对它们不足之处进行了改进,提出了一种新的基于双簇首节能的无线传感器网络分簇拓扑控制算法,即DCHEB算法。该算法提出了一种新的簇划分方案,通过此方案可以对无线传感器网络进行合理分簇,使得簇首节点位于合适的位置上,平均了各个簇的节点个数,可以避免簇内的边缘节点过早死亡。最后通过理论分析和仿真工具验证了该算法对减少无线传感器网络的能量消耗和延长其生存时间有很好的作用。     

路由深度对Sink轨迹固定传感器网络的影响

无线传感器网络中,使用移动Sink进行数据采集能够减少网络节点死亡速度,延长网络时间,是最有效均衡网络负载的方法之一。在实际应用中,移动Sink通常采用固定路径策略,同时路由深度的改变直接影响网络拓扑和路由选择结果。比较了在不同路由深度下,采用4种典型固定策略的移动Sink网络的网络能耗、网络寿命和包延时。仿真结果表明:在较小的路由深度下,外边界策略能更好地降低节点能耗,延长网络寿命;内边界策略能取得更好的覆盖和较低的时延。     

基于功耗模型的无线传感器网络节点生存模式评估

作为一种能量受限网络,无线传感器网络节点能耗评估具有重要意义。分析组成无线传感器网络节点各个单元功耗与状态的关系,建立基于节点工作状态的功耗模型,提出节点生存模式评估方法。给出典型节点生存模式实验用例,在振动检测实验平台上进行相关参数测量与验证。实验数据表明：该方法优于Petri网模型,可为无线传感器网络节点节能优化提供较为可靠的依据。