Beacon-Less Geographic Routing in Real Wireless Sensor Networks

Geographic Routing(GR)algorithms require nodes to periodically transmit HELLO messages to allow neigh- bors to know their positions(beaconing mechanism).Beacon-less routing algorithms have recently been proposed to reduce the control overheads due to these messages.However,existing beacon-less algorithms have not considered realistic physical layers.Therefore,those algorithms cannot work properly in realistic scenarios.In this paper we present a new beacon- less routing protocol called BOSS.Its design is based on the conclusions of our open-field experiments using Tmote-sky sensors.BOSS is adapted to error-prone networks and incorporates a new mechanism to reduce collisions and duplicate messages produced during the selection of the next forwarder node.We compare BOSS with Beacon-Less Routing(BLR) and Contention-Based Forwarding(CBF)algorithms through extensive simulations.The results show that our scheme is able to achieve almost perfect packet delivery ratio(like BLR)while having a low bandwidth consumption(even lower than CBF).Additionally,we carried out an empirical evaluation in a real testbed that shows the correctness of our simulation results.     

Balancing the power consumption speed in flat and hierarchical WSN

A combination of a cluster tree routing protocol and an Ad hoc on demand vector (AODV) routing protocol is used in the latest ZigBee standard wireless sensor networks (WSNs) technology. However, the AODV routing protocol has no means by which to take into consideration the power consumption of the nodes during the routing process. Therefore, a new approach is proposed in this paper to balance the power consumption speed and to distribute the responsibilities of routing among fiat wireless sensor nodes and the three levels of hierarchical wireless sensor nodes. These three levels are based on the three types of devices, which are used in the ZigBee standard: the coordinator, the touters, and the end devices. In this paper, we have compared the original AODV routing protocol with our extension approach for the distribution of power consumption. Based on the simulation results, our new approach has achieved better performance in terms of increasing the lifetime of the fiat wireless sensor network, the personal area network (PAN)coordinator, the touters, and the whole network of the hierarchical wireless sensor network. Additionally, it has better performance in terms of distributing the power consumption among the key nodes of the wireless sensor network.     

High dynamic adaptive mobility network model and performance analysis

Since mobile networks are not currently deployed on a large scale, research in this area is mostly by simulation. Among other simulation parameters, the mobility model plays a very important role in determining the protocol performance in MANET. Based on random direction mobility model, a high dynamic adaptive mobility network model is proposed in the paper. The algorithms and modeling are mainly studied and explained in detail. The technique keystone is that normal distribution is combined with uniform distribution and inertial feedback control is combined with kinematics, through the adaptive control on nodes speed and prediction tracking on nodes routes, an adaptive model is designed, which can be used in simulations to produce realistic and dynamic network scenarios. It is the adaptability that nodes mobile parameters can be adjusted randomly in threedimensional space. As a whole, colony mobility can show some rules. Such random movement processes as varied speed and dwells are simulated realistically. Such problems as sharp turns and urgent stops are smoothed well. The model can be adapted to not only common dynamic scenarios, but also high dynamic scenarios. Finally, the mobility model performance is analyzed and validated based on random dynamic scenarios simulations.     

Unicast routing protocols for urban vehicular networks: review,taxonomy, and open research issues

Over the past few years, numerous traffic safety applications have been developed using vehicular ad hoc networks（VANETs）. These applications represent public interest and require network-wide dissemination techniques. On the other hand, certain non-safety applications do not require network-wide dissemination techniques.Such applications can be characterized by their individual interest between two vehicles that are geographically apart. In the existing literature, several proposals of unicast protocols exist that can be used for these non-safety applications. Among the proposals, unicast protocols for city scenarios are considered to be most challenging.This implies that in city scenarios unicast protocols show minimal persistence towards highly dynamic vehicular characteristics, including mobility, road structure, and physical environment. Unlike other studies, this review is motivated by the diversity of vehicular characteristics and difficulty of unicast protocol adaption in city scenarios.The review starts with the categorization of unicast protocols for city scenarios according to their requirement for a predefined unicast path. Then, properties of typical city roads are discussed, which helps to explore limitations in efficient unicast communication. Through an exhaustive literature review, we propose a thematic taxonomy based on different aspects of unicast protocol operation. It is followed by a review of selected unicast protocols for city scenarios that reveal their fundamental characteristics. Several significant parameters from the taxonomy are used to qualitatively compare the reviewed protocols. Qualitative comparison also includes critical investigation of distinct approaches taken by researchers in experimental protocol evaluation. As an outcome of this review, we point out open research issues in unicast routing.     

A Routing Protocol for Enhanced Efficiency in Cognitive Radio Networks

This paper proposes a novel routing protocol enriched with an assigning mechanism that enables for efficient data flow coordination, among communication nodes with heterogeneous spectrum availability in distributed cognitive radio networks. Efficient routing protocol operation, as a matter of maximum-possible routing paths establishments and minimum delays is obtained, by utilizing a signaling mechanism that was developed based on a simulation scenario. This simulation scenario includes a number of secondary communication nodes, operating over TVWS （television white spaces） under the ＂spectrum of commons＂ regulation regime. The validity of the proposed routing protocol for enhanced efficiency in cognitive radio networks is validated, by conducting experimental simulations and obtaining performance evaluation results. Simulation results verified the efficiency of the proposed routing protocol for minimizing routing delays among secondary communication nodes and indentified fields for further research.     

Output constrained IMC controllers in control systems of electromechanical actuators

Electromechanical actuators are widely used in many industrial applications. There are usually some constraints existing in a designed system. This paper proposes a simple method to design constrained controllers for electromechanical actuators. The controllers merge the ideas exploited in internal model control and model predictive control. They are designed using the standard control system structure with unity negative feedback. The structure of the controllers is relatively simple as well as the design process. The output constraint handling mechanism is based on prediction of the control plant behavior many time steps ahead. The mechanism increases control performance and safety of the control plant. The benefits offered by the proposed controllers have been demonstrated in real-life experiments carried out in control systems of two electromechanical actuators: a DC motor and an electrohydraulic actuator.     

Maximizing the Delivery of MPR Broadcasting Under Realistic Physical Layer Assumptions

It is now commonly accepted that the unit disk graph used to model the physical layer in wireless networks does not reflect real radio transmissions,and that a more realistic model should be considered for experimental simulations. Previous work on realistic scenarios has been focused on unicast,however broadcast requirements are fundamentally different and cannot be derived from the unicast case.Therefore,the broadcast protocols must be adapted in order to still be efficient under realistic assumptions.In this paper,we study the well-known multipoint relay broadcast protocol(MPR),in which each node has to choose a set of 1-hop neighbors to act as relays in order to cover the whole 2-hop neighborhood.We give experimental results showing that the original strategy used to select these multipoint relays does not suit a realistic model. On the basis of these results,we propose new selection strategies solely based on link quality.One of the key aspects of our solutions is that our strategies do not require any additional hardware and may be implemented at the application layer, which is particularly relevant to the context of ad hoc and sensor networks where energy savings are mandatory.We finally provide new experimental results that demonstrate the superiority of our strategies under realistic physical assumptions.     

Random Walk Routing in WSNs with Regular Topologies

Topology is one of the most important characteristics for any type of networks because it represents the network's inherent properties and has great impact on the performance of the network. For wireless sensor networks (WSN), a well-deployed regular topology can help save more energy than what a random topology can do. WSNs with regular topologies can prolong network lifetime as studied in many previous work. However, little work has been done in developing effective routing algorithms for WSNs with regular topologies, except routing along a shortest path with the knowledge of global location information of sensor nodes. In this paper, a new routing protocol based on random walk is proposed. It does not require global location information. It also achieves load balancing property inherently for WSNs which is difficult to achieve by other routing protocols. In the scenarios where the message required to be sent to the base station is in comparatively small size with the inquiry message among neighboring nodes, it is proved that the random walk routing protocol can guarantee high probability of successful transmission from the source to the base station with the same amount of energy consumption as the shortest path routing. Since in many applications of WSNs, sensor nodes often send only beep-like small messages to the base station to report their status, our proposed random walk routing is thus a viable scheme and can work very efficiently especially in these application scenarios. The random walk routing provides load balancing in the WSN as mentioned, however, the nodes near to the base station are inevitably under heavier burden than those far away from the base station. Therefore, a density-aware deployment scheme is further proposed to guarantee that the heavy-load nodes do not affect the network lifetime even if their energy is exhausted. The main idea is deploying sensors with different densities according to their distance to the base station. It will be shown in this paper that incorporating the random walk routing protocol with the density-aware deployment scheme can effectively prolong the network lifetime.     

基于SUMO的路由协议仿真研究

利用TIGER数据库,构建一个实际道路地图作为仿真场景,借助SUMO交通仿真器和NS2网络仿真平台,评估ADOV、DSR、DSDR 3种路由协议在城市场景车载自组网(VANET)中的适用性.实验结果表明,上述3种协议在城市VANET环境下,存在分组传输成功率低、归一化路由负载高、平均端到端延时大的缺点,难以满足现有城市...     

城市场景下VANET路由协议大规模仿真研究

车载自组网(VANET)是移动Ad Hoe网络(MANET)技术在交通领域的应用,由于VANET独特的场景特点,需要重新评估MANET中路由协议在VANET场景下的适用程度.为了提高仿真实验结果的准确性,实现了车辆运动模型并结合西安城区卫星地图构造了逼真的城市道路场景.在场景下利用QualNet仿真平台进行了大规模的路由协议仿真实验,评估了四种典型的MANET路由协议在城市场景VANET中的适用性.结果表明,这些协议难以满足通信需求,不适合用于城市环境下车载自组网研究.     

LTE中基于协作AODV协议的拥塞控制机制研究

针对LTE网络已有的拥塞控制算法无法适应分布式网络拓扑和复杂的网络环境以及自身效率低、开销大等问题,分析了LTE网络无线信道质量对AODV协议性能的影响,建立了基于路径损耗门限值的协同合作方式下的AODV路由机制,在此基础上,提出了一种基于队列长度和跳数的拥塞控制策略,分别通过LTE网络链路级仿真实验验证了改进后的基于协作路由协议的无线TCP拥塞控制机制的性能。数学分析和仿真结果表明,所提协作拥塞控制机制与传统的TCP拥塞控制机制相比,在平均丢包数、队列长度抖动、时延、时延抖动和吞吐率等方面均具有良好的性能。     

无线自组织网络中TCP稳定性的分析及改进

在无线自组织网络中,基于IEEE 802.11的TCP流存在严重的不稳定性,其原因与MAC协议、路由协议和TCP本身均有一定的关系,但最根本之处在于MAC协议的不公平性以及假的链路失效消息导致了不必要的耗时的路由发现过程.结合IEEE802.11的MAC协议和DSR路由协议,对这些原因进行了深入的理论分析和仿真实验,并提出了针对MAC协议和路由协议的改进算法.仿真结果证明,提出的改进算法不仅能基本上避免TCP流的不稳定性,还能够极大地提高TCP流的平均吞吐量.     

基于蚁群算法的路由协议在TinyOS中的实现

为了提高无线传感器网络(WSNs)的通信链路质量,在TinyOS系统中实现了基于蚁群算法的路由协议,该协议采用多跳的通信方式,为应用程序提供较为可靠的数据传输服务。结合Zig Bee网络的体系结构,详述了该协议的实现流程。通过TOSSIM仿真平台对该协议进行了验证,仿真结果表明:基于蚁群算法的路由协议能够在降低丢包率和传输延时的同时平衡节点的能量消耗,进而延长整个网络的存活时间。     

AODV 协议在ARM 平台上的移植技术研究

针对AODV 协议大多在理论或是仿真中进行研究的问题,分析当前主流ARM 平台的体系架构和AODV 协议 的运行机制,研究AODV 协议移植到主流ARM 平台的新方法。搭建了一个包含四个实际节点的验证环境,运行了新的 AODV 协议,为AODV 协议移植ARM 平台提供参考。     

Ad Hoc路由协议在不同移动环境中的性能仿真

影响Ad Hoc网络路由性能的因素很多,如节点的移动、网络的负载、节点数目的变化等;而其中节点的移动是其中最关键的因素之一.该文对四种典型的路由协议进行了理论分析,并提出了一个仿真模型,使得节点在网络所在区域内以不同的速度移动.利用GlomoSim仿真工具对四种路由协议进行了仿真,对路由协议主要的几种参数：平均报文接收率、平均端到端的延时与路由控制报文的总负载进行了统计分析.仿真结果与理论分析一致,并对仿真结果进行了详细的分析比较,得出了AODV路由协议最适合移动要求较高的网络的结论.     

基于NS2的AODV路由协议仿真及分析

对Ad hoc网络中的AODV路由协议进行简要介绍,利用网络仿真软件NS2对AODV路由协议进行仿真,通过不同仿真场景计算出各种情况下AODV协议的平均时延、归一化路由开销、分组投递率和网络抖动,并根据结果分析这4种参数对AODV路由协议的影响,最后得出结论 AODV适合于中小规模且发包率较低的场合。     

基于Petri网的PIM—SM协议建模与分析

随着组播技术的飞速发展和广泛应用，对其路由协议进行数学建模和分析已经成为计算机网络领域一个重要的研究问题。其中PIM—SM协议是目前Intemet上最广泛应用的城内组播路由协议。针对PIM—SM协议的复杂、异步的特点．在对PIM-SM协议机制详细分析的基础上，利用Petri网对其进行形式化描述和建模，为协议进行性能分析、系统仿真和具体实现提供理论基础。     

MANET 中基于链路稳定性路由的跨层传输控制协议

在MANET中,通信节点的移动会造成端到端通信路由的时常中断.传统TCP协议只有拥塞控制机制,对由于节点移动造成的数据包传输丢失和超时也作为拥塞处理,使得端到端传输性能低下.为解决这一问题,采用跨层设计思想,将传输控制与链路稳定性路由结合,提出了一种基于链路生存时间概率的传输控制协议(transmissioncontrol protocol based on probability of link residual lifetime,简称TCP-PLRT).该协议通过在路由稳定时跨层收集路由层链路生存时间概率信息来实现对端到端连接稳定性的认知,并针对路由不稳定、路由中断、路由恢复,分别制定了路由切换、数据存储转发、ACK再确认三大机制.这使得TCP-PLRT协议具有对由移动造成的路由中断进行提前预判和有效处理的能力.仿真结果表明,TCP-PLRT协议能够极大地减小由节点移动带来的端到端传输性能的下降,减少分组重传,提高端到端的吞吐量.