Battery modeling for energy aware system design

Advances in battery technology have not kept pace with rapidly growing energy demands. Most laptops, handheld PCs, and cell phones use batteries that take anywhere from 1.5 to 4 hours to fully charge but can run on this charge for only a few hours. The battery has thus become a key control parameter in the energy management of portables. To meet the stringent power budget of these devices, researchers have explored various architectural, hardware, software, and system-level optimizations to minimize the energy consumed per useful computation. Research in battery-aware optimization is now moving from stand-alone devices to networks of wireless devices, specifically, ad hoc and distributed sensor networks. Computationally feasible mathematical models are now available that capture battery discharge characteristics in sufficient detail to let designers develop an optimization strategy that extracts maximum charge.     

Making the gigabit IPsec VPN architecture secure

By placing the security processors directly in the data path to secure traffic without the aid of additional outside devices or software, the flow-through security device creates a virtual private network that maximizes network processing unit host offload with minimal system integration effort. A virtual private network uses the Internet protocol security (IPsec) framework to provide confidentiality, data integrity, and end point authentication. These features protect corporate data from being viewed or tampered with while in transit over the Internet. Additionally, the VPN supports data compression, which increases Internet performance between sites. Metropolitan area networks and storage area networks lead the trend toward gigabit Ethernet installations that seek to provide higher speed and better security. The decreasing cost of gigabit devices and their increasing availability in PCs are driving the use of gigabit MAN, while increasing data rates drive the use of gigabit SANs as the bit rate to hard-disk media approaches 1 gigabit per second.     

一种无线传感器网络路由协议的研究与改进

无线传感器网络由许多具有低功率无线收发装置的传感器节点组成,能够有效地感知、采集和处理网络覆盖区域中的相关信息,并发送给远处的基站进一步处理。由于传感器节点能量有限,路由协议必须尽可能地减少能量消耗,延长网络生命周期。对经典的LEACH路由协议进行研究,并针对簇头节点和基站的通信方式提出改进,用M atlab平台下对LEACH算法和改进后的算法进行仿真分析,结果显示:改进后的算法在延长网络生命周期和减少能量消耗上比LEACH算法有了很大改善。     

放置中继节点解决无线传感器网络能量空洞问题

在无线传感器网络中,传感器节点往往采用多跳的方式进行数据传输,造成了基站sink周围节点能量消耗过快,易形成能量空洞问题。针对这个问题,提出了一种改变中继节点能量的能耗均衡策略,即将中继节点的能量加大为原传感器节点能量的数倍,同时减少中继节点的数量。理论分析和仿真结果表明,这种方法有效地解决了能量空洞问题。考虑到成本和数据冗余问题,在中继节点数为理想数目的3/5时,网络能耗没有太大的提高,即放置少量的中继节点也能达到能耗均衡的目的。     

机会网络蓝牙设备唤醒调度机制研究

在以人为载体的机会网络中,移动蓝牙设备有电池能量有限的特点。同时,在机会网络中,节点经常处于较长时间的互不连通状态,如何设计有效的蓝牙节点唤醒调度模式来降低能耗并确保不破坏网络现有的连通性是一个重要问题。提出了一种机会网络蓝牙设备唤醒调度策略BWM。该策略分析蓝牙设备电池能耗问题,建立了涉及能耗的蓝牙数据传输模型,并对休眠唤醒机制中的参数内在联系进行研究,以确保数据成功传输量为前提来对唤醒周期间隔长度进行控制。仿真实验结果表明,BWM在保证节点有效数据发送性能前提下节省了节点消耗的能量。     

Energy-saving model for SDN data centers

With the development of the Internet, data centers have become vital infrastructures which provide computing, storage and other services for the networks. According to statistics, data centers consume large amount of electricity all around the world. In most cases, the majority of network devices in data centers are relatively idle, resulting in a waste of energy. Software defined network (SDN) was proposed by UC Berkeley and Stanford University around 2008, which allows the administrators to manage the network and set configurations through abstraction of lower level functionality. It also separates the control plane and the data plane, so administrators can control the network traffic through centralized controller instead of access to physical devices. This paper discusses the energy-saving model in data center networks based on SDN. We propose two different energy-saving algorithms, which can be applied to different data centers. Through centralized management and preprocessing traffic by SDN, we get better energy efficiency and reduce the energy cost by 30–40 %. To the best of our knowledge, this is the first work on energy saving in SDN architecture which provides two different algorithms that can be applied in different scenarios.     

基于分布式邻居发现机制的ZigBee网络能耗研究

ZigBee是一种基于IEEE 802.15.4标准的适用于短距离、低功耗和低数据传输率的无线网络技术。ZigBee网络的节点电池能量的有效利用能延长其网络生命周期。采用分布式邻居发现机制研究了ZigBee网络能耗。该机制使得ZigBee网络中的节点在其可访问的区域内及时发现邻居节点,通过分析和定义3种分布式邻居发现算法下ZigBee节点在整个发现过程中所需要的平均帧数,提出了ZigBee网络能耗模型,对ZigBee网络设备在3种分布式邻居发现算法下的能耗进行了详细分析并得出能耗表达式。在仿真实验中比较了ZigBee网络节点和邻居节点在不同算法下的工作循环模式和连续模式下设备的能耗,结果表明对于基于分布式邻居发现机制算法的ZigBee网络能耗,当帧时隙数较小时,选择争用树算法能获得较好的节能效果;当帧时隙数较大时,选择无反馈帧时隙算法或有反馈帧时隙算法则可减少节点能耗以延长ZigBee网络的生命周期。     

Impact of Transmission Power Control in multi-hop networks

Many Transmission Power Control (TPC) algorithms have been proposed in the past, yet the conditions under which they are evaluated do not always reflect typical Internet-of-Things (IoT) scenarios. IoT networks consist of several source nodes transmitting data simultaneously, possibly along multiple hops. Link failures are highly frequent, causing the TPC algorithm to kick-in quite often. To this end, in this paper we study the impact that frequent TPC actions have across different layers. Our study shows how one node’s decision to scale its transmission power can affect the performance of both routing and MAC layers of multiple other nodes in the network, generating cascading packet retransmissions and forcing far too many nodes to consume more energy. We find that crucial objectives of TPC such as conserving energy and increasing network capacity are severely undermined in multi-hop networks.     

WSN in cyber physical systems: Enhanced energy management routing approach using software agents

Recently, the cyber physical system has emerged as a promising direction to enrich the interactions between physical and virtual worlds. Meanwhile, a lot of research is dedicated to wireless sensor networks as an integral part of cyber physical systems. A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices that use sensors to monitor physical or environmental conditions. These autonomous devices, or nodes, combine with routers and a gateway to create a typical WSN system. Shrinking size and increasing deployment density of wireless sensor nodes implies the smaller equipped battery size. This means emerging wireless sensor nodes must compete for efficient energy utilization to increase the WSN lifetime. The network lifetime is defined as the time duration until the first sensor node in a network fails due to battery depletion. One solution for enhancing the lifetime of WSN is to utilize mobile agents. In this paper, we propose an agent-based approach that performs data processing and data aggregation decisions locally i.e., at nodes rather than bringing data back to a central processor (sink). Our proposed approach increases the network lifetime by generating an optimal routing path for mobile agents to transverse the network. The proposed approach consists of two phases. In the first phase, Dijkstra’s algorithm is used to generate a complete graph to connect all source nodes in a WSN. In the second phase, a genetic algorithm is used to generate the best-approximated route for mobile agents in a radio harsh environment to route the sensory data to the base-station. To demonstrate the feasibility of our approach, a formal analysis and experimental results are presented.     

What ITIL can Teach IT-GRC

Abstract

Essentially, the simple network management protocol (SNMP) is a collection of command and query instructions that can be used to inspect and reconfigure the performance characteristics of such local area and wide area network-connected devices as routers, filters, bridges, and repeaters. SNMP collects data from variables that are defined by logic in management information bases (MIBs). These variables reside physically, in turn, as counters or as rudimentary tables in software agents that are located in the devices that are being observed and controlled.     

Bandwidth-aware energy efficient flow scheduling with SDN in data center networks

Nowadays the energy consumption has become one of the most urgent issues for Data center networks. For general network devices, the power is constant and independent from the actual transfer rate. Therefore the network devices are energy efficient when they are in full workload. The flow scheduling methods based on the exclusive routing can reduce the network energy consumption, as the exclusive routing paths can fully utilize all their links. However, these methods will no longer guarantee the energy efficiency of switches, as they handle flows in priority order by greedily choosing the path of available links instantaneously. In a previous work we proposed an extreme case of flow scheduling based on both link and switch utilization. Herein we consider general scenarios in data center networks and propose a novel energy efficient flow scheduling and routing algorithm in SDN. This method minimizes the overall energy for data center traffic in time dimension, and increases the utilization of switches and meet the flow requirements such as deadline. We did a series of simulation studies in the INET framework of OMNet++. The experiment results show that our algorithm can reduce the overall energy with respect to the traffic volume and reduce the flow completion time on average.     

无线传感器网络中信道接入分簇算法的研究

传感器技术、微机电系统、现代网络和无线通信等技术的进步,推动了具有现代意义的无线传感器网络的产生和发展。无线传感器网络能够广泛应用于恶劣环境和军事领域中。其中针对如何延长传感器网络的生存周期,降低传感节点的能量消耗成为研究的重点问题。文章通过分析无线传感器网络的特点和分簇算法的优点,提出新的基于信道接入分簇算法的路由解决方案,通过与已有的基于信道接入分簇算法的比较,新的分簇算法能够大大降低系统的能耗和复杂度,延长网络的寿命。最后,利用OPNET网络仿真工具给出相关的仿真结果。     

An ant swarm-inspired energy-aware routing protocol for wireless ad-hoc networks

Primitive routing protocols for ad-hoc networks are “power hungry” and can therefore consume considerable amount of the limited amount of battery power resident in the nodes. Thus, routing in ad-hoc networks is very much energy-constrained. Continuous drainage of energy degrades battery performance as well. If a battery is allowed to intermittently remain in an idle state, it recovers some of its lost charge due to the charge recovery effect, which, in turn, results in prolonged battery life.In this paper, we use the ideas of naturally occurring ants’ foraging behavior (Dorigo and Stuetzle, 2004) [1] and based on those ideas, we design an energy-aware routing protocol, which not only incorporates the effect of power consumption in routing a packet, but also exploits the multi-path transmission properties of ant swarms and, hence, increases the battery life of a node. The efficiency of the protocol with respect to some of the existing ones has been established through simulations. It has been observed that the energy consumed in the network, the energy per packet in the case of EAAR are 60% less compared to MMBCR and the packets lost is only around 12% of what we have in AODV, in mobility scenarios.     

基于能量强度的簇区分路由方法研究

传感器节点体积微小,通常携带能量十分有限的电池。由于传感器节点个数多,成本要求低廉,分布区域广,而且部署区域环境复杂,有些区域甚至是人员不能到达的,所以传感器节点通过更换电池的方式来补充能量是不现实的。如何高效使用能量来最大化网路的生命周期是无线传感器网络面临的首要挑战。为了提高网络的寿命,目前人们已经提出了很多基于网络层的路由协议。比较研究了传感器网络现有的路由协议,参考LEACH分簇算法和MTP协议,提出了一种在MTP协议基础上将LEACH分簇思想引入进来的改进方法,即在基于能量强度将网络节点分层后,再在各层上进行簇区分,均衡各传感器节点的能量来提高网络的寿命。实验表明该路由算法可提高网络寿命。     

A fuzzy-based Power-aware management for mobile ad hoc networks

In recent years, people have become more dependent on wireless network services to obtain the latest information at any time anywhere. Wireless networks must effectively allow several types of mobile devices send data to one another. The Mobile Ad Hoc Network (MANET) is one important type of non-infrastructure mobile network that consists of many mobile hosts, usually cellular phones. The power consumption rate and bandwidth of each mobile host device becomes an important issue and needs to be addressed. For increasing the reliability of the manager in Hierarchical Cellular Based Management (HCBM), this paper proposed a Power-aware protocol to select a stable manager from mobile hosts by fuzzy based inference systems based on the factors of speed, battery power, and location. Further, our protocol can trigger a mobile agent to distribute the managerial workload.     

BARC: A Battery Aware Reliable Clustering algorithm for sensor networks

Clustering in wireless sensor networks (WSNs) provides scalability and robustness for the network; it allows spatial reuse of the bandwidth, simpler routing decisions, and results in decreased energy dissipation of the whole system by minimizing the number of nodes that take part in long distance communication. Clustering allows for data aggregation which reduces congestion and energy consumption. Recent study in battery technology reveals that batteries tend to discharge more power than needed and reimburse the over-discharged power if they are recovered. In this paper, we first provide an online mathematical battery model suitable for implementation in sensor networks. Using our battery model, we propose a new Battery Aware Reliable Clustering (BARC) algorithm for WSNs. BARC incorporates many features which are missing in many other clustering algorithms. It rotates cluster heads (CHs) according to a battery recovery scheme and it also incorporates a trust factor for selecting cluster heads thus increasing reliability. Most importantly, our proposed algorithm relaxes many of the rigid assumptions that the other algorithms impose such as the ability of the cluster head to communicate directly with the base station and having a fixed communication radius for intra-cluster communication. BARC uses Z-MAC which has several advantages over other MAC protocols. Simulation results show that using BARC prolongs the network lifetime greatly in comparison to other clustering techniques.     

Enhanced AODV routing protocol for Bluetooth scatternet

Bluetooth is one of the most widespread technologies for personal area networks that allow portable devices to form multi-hop Bluetooth ad hoc networks, so called scatternets. Routing is one of the challenges in scatternets because of its impact on the performance of the network. It should focus on reducing the power consumption in the network because most of the nodes are battery-operated portable devices. In this paper, we propose a routing protocol for Bluetooth scatternets that customizes the Ad hoc On-Demand Distance Vector (AODV) routing protocol by making it power-aware and suitable for scatternets. It enhances the AODV flooding mechanism by excluding all non-bridge slaves from taking apart in the AODV route discovery process. In addition, it improves the AODV route discovery phase by considering the hop count, the predicated node’s power, and the average traffic intensity for each node as metrics for best route selection. By removing HELLO packets, our protocol reduces the control packets overhead and the power consumption in network devices. Simulation results show that the proposed protocol achieved considerable improvements over other enhanced AODV protocols by increasing the data delivery ratio by 10.78%, reducing the average end-to-end delay by 8.11%, and reducing the average energy consumption by 7.92%.     

Application of a JXTA-overlay P2P system for end-device control and e-learning

This work is motivated by the need to develop decentralized P2P approaches for controlling end-devices in a wide-area network without changing the network security policy. Much of current research work on P2P systems is devoted to P2P networks of standard peers such as PCs. Due to improvements of connections capabilities of mobile devices and end-devices, there is an increasing interest to design, implement and deploy full featured P2P networks that integrate standard peers, mobile devices and end-devices. In this paper, we use the JXTA-Overlay for the control of end-devices and e-learning in a P2P network. We considered as end-devices the smart box (which is used for stimulating the learners in our implemented P2P e-learning system), robot, and room lightening. We also considered the control of a mobile car in order to prove the applicability of our approach in wireless environment. The proposed approach, due to the capabilities of JXTA protocols to overcome firewalls and NATs, is able to control devices without changing network security policies. We evaluate the proposed system by many experiments and have shown that the proposed system has a good performance and can be used successfully for the control of end-devices and in e-learning.     

Efficient solution techniques for the integrated coverage, sink location and routing problem in wireless sensor networks

Sensors are tiny electronic devices having limited battery energy and capability for sensing, data processing and communicating. They can collectively behave to provide an effective wireless network that monitors a region and transmits the collected information to gateway nodes called sinks. Most of the applications require the operation of the network for long periods of times, which makes the efficient management of the available energy resources an important concern. There are three major issues in the design of sensor networks: sensor deployment or the coverage of the sensing area, sink location, and data routing. In this work, we consider these three design problems within a unified framework and develop two mixed-integer linear programming formulations. They are difficult to solve exactly. However, it is possible to compute good feasible solutions of the sink location and routing problems easily, when the sensors are deployed and their locations in the sensor field become known. Therefore, we propose a tabu search heuristic that tries to identify the best sensor locations satisfying the coverage requirements. The objective value corresponding to each set of sensor locations is calculated by solving the sink location and routing problem. Computational tests carried out on randomly generated test instances indicate that the proposed hybrid approach is both accurate and efficient.