A lightweight soft-state tracking framework for dense mobile ad hoc networks

In a mobile ad hoc network, tracking protocols need to deal with–in addition to the mobility of the target–the mobility of the intermediate nodes that maintain a track toward the target. To address this problem, we propose the MDQT (Mobility-enhanced Distributed QuadTree) tracking framework. MDQT employs a static cell abstraction to mask the mobility of the nodes and provide the illusion of a logical static network overlaid on the mobile network. MDQT implements this virtual static network layer in a lightweight/communication-free manner by exploiting the soft-state principle and the snooping feature of wireless communication.Through simulation, we study the impacts of the mobile node percentage and target mobility speed on the system performance. Simulation results show that the success rate of tracking is mostly unaffected by the speed of mobile nodes, but degrades slightly with the increases in mobile node percentage. On the other hand, the cost measurements (latency, average hops, and retry rate) are more sensitive to the mobility speed, and remain unaffected by the increase of mobile node percentage—owing to our soft-state design approach. We find that even at very high mobility speeds (50 m/s), low update rates (1 update per second), and 100% node mobility, the success rate of MDQT tracking is above 85% and the latency is comparable with that of static networks.     

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.     

Exploiting mobility patterns for inter-technology handover in mobile environments

Mobile terminals with multi-radio devices have become increasingly prevalent. This makes it possible for Internet applications to be supported by heterogeneous wireless networks while the terminal is on the move. As the user is constantly moving, it is highly desirable that the terminal connects to the best network and retains high performance of network connections. Handovers can be made within the same type of network (horizontal handover) or different types of networks (vertical handover). This paper focuses on link-layer inter-technology vertical handovers. Vertical handovers present several great challenges, such as user mobility randomness, high handover overhead and optimality requirement. Existing work often focuses only on the current network condition when making handover decisions, ignoring future performance of the terminal. As a result, a handover decision good for the current moment may soon become poor when the user moves to another place. This paper is motivated by the observation that users in a given mobile environment, such as university or enterprise campus, exhibit clear mobility patterns. We propose an approach for making handover decisions, which explicitly exploits user mobility patterns. This approach can produce high-performance handover decisions in the long run. Employing a comprehensive framework for preference customization, the approach supports user customization caring for different user preferences. Extensive real trace driven simulations and comparative study show our algorithm is better than the conventional vertical handover algorithms.     

A token based distributed algorithm for supporting mutual exclusion in opportunistic networks

Opportunistic networks are essentially distributed networks with transient connectivity among nodes. Nodes in opportunistic networks are resource constrained, mobile and opportunistically come in contact with each other. In such a distributed network, nodes may require exclusive access to a shared object or resource. Ensuring freedom from starvation is a challenging problem in opportunistic networks due to limited pairwise connectivity and node failures. In this paper, we review mutual exclusion algorithms proposed for generic mobile ad hoc networks (MANETs) and discuss their applicability to opportunistic networks. Further, we propose a novel token based algorithm¹ and prove its correctness. Simulation results show that our algorithm is communication efficient as compared to other algorithms proposed for generic mobile ad hoc networks. We also propose a timeout based fault detection algorithm that exploits the intercontact time distributions.     

Service discovery in mobile ad hoc networks: A field theoretic approach

Service discovery in mobile ad hoc networks is challenging because of the absence of any central intelligence in the network. Traditional solutions as used in the Internet are hence not well suited for mobile ad hoc networks. In this paper, we present a novel decentralized service discovery mechanism for ad hoc networks. The basic idea is to distribute information about available services to the network neighborhood. We achieve this by using the analogy of an electrostatic field: A service is modelled by a (positive) point charge, and service request packets are seen as (negative) test charges which are attracted by the service instances. In our approach, we map the physical model to a mobile ad hoc network in a way where each network element calculates a potential value and routes service requests towards the neighbor with the highest potential, hence towards a service instance. Our approach allows for differentiation of service instances based on their capacity. We define the required protocols and methods which we implemented in a network simulator. Using extensive simulations, we evaluate the performance and robustness of the mechanisms. The results indicate good performance and convergence even in highly mobile environments. We believe that this technique can and should be further exploited, e.g., as a routing protocol in mobile ad hoc networks.     

Addressing and routing in hexagonal networks with applications for tracking mobile users and connection rerouting in cellular networks

Nodes in a hexagonal network are placed at the vertices of a regular triangular tessellation, so that each node has up to six neighbors. The network is proposed as an alternative interconnection network to a mesh connected computer (with nodes serving as processors) and is used also to model cellular networks where nodes are the base stations. In this paper, we propose a suitable addressing scheme for nodes (with two variants), derive a formula for distance between nodes, and present a very simple and elegant routing algorithm. This addressing scheme and corresponding routing algorithm for hexagonal interconnection are considerably simpler than previously proposed solutions. We then apply the addressing scheme for solving two problems in cellular networks. With the new scheme, the distance between the new and old cell to which a mobile phone user is connected can be easily determined and coded with three integers, one of them being zero. Further, in order to minimize the wireless cost of tracking mobile users, we propose hexagonal cell identification codes containing three, four, or six bits, respectively, to implement a distance based tracking strategy. These schemes do not have errors in determining cell distance in existing hexagonal based cellular networks. Another application is for connection rerouting in cellular networks during a path extension process.     

非线性离散时间系统的最优终端迭代学习控制

仅利用系统的终端输出误差而不是整个输出轨迹,提出了一种最优终端迭代学习控制方法.控制信号可直接通过终点的误差信息进行更新.主要创新点在于控制器的设计和分析只利用系统量测的I/O数据而不需要关于系统模型的任何信息,并可实现沿迭代轴的单调收敛.在此意义上,所提出的控制器是数据驱动的无模型控制方法.严格的数学分析和仿真结果均表明了所提出方法的适用性和有效性.     

移动对等网络体系结构的研究与设计

随着科学技术的进步,移动用户的日渐增多和移动网络应用环境的逐渐成熟,人们对移动网络的速度要求越来越高,使得无线网络上P2P技术的需求日渐强烈。众所周知,无线网络通信和终端的移动性使得网络在带宽、延迟、连接可靠性、连接维持可预期性等通信性能上与有线网络相比相差很远。可以利用移动P2P方式提供的视频点播、资源共享和移动协同计算等,提高网络的性能。     

Active network supports for mobile IP

The basic mobile IP protocol is difficult to implement on the traditional IP network and not flexible and efficient under certain conditions.For example,firewalls or boundary routers may drop packets sent by mobile nodes for security reasons.Traditional networking devices such as routers cannot dynamically load and unload extended services to achieve different qualities of services.In this paper,a new scheme of using the active network to support the mobile IP is presented.The Softnet,a prototype of active networks based on mobile agents,is introduced.The active network is characterized by the programmability of its intermediate nodes and therefore presents dynaic and flexible behaviors.Special services can be dynamically deployed onto the active nodes in the Softnet.This property is definitely required in implementing the mobile IP protocols.The SOftnet.This property is definitely required in implementing the mobile IP protocols.The Softnet.This property is definitely required in implementing the mobile IP protocols.The Softnet supports not only the basic mobile IP protocol but also other extended mobile IP protocols.Virtual networks for mobile IP services are dynamically formed by mobile agents in the Softnet to provide different qualities of services.     

一种移动终端辅助的传感器网络数据收集协议

提出了一种利用具有传感器通信接口的移动终端设备（如手机、手提电脑、个人数字助理等）进行辅助数据获取的传感器网络数据收集协议。网络中固定汇聚节点与移动终端共存,全部传感器节点都维护到固定汇聚节点的路由,移动终端进入网络后定期向其附近小范围内的传感器节点扩散自己的存在信息,传感器节点向距自己跳数最小的汇聚节点或移动终端发送或转发数据包,移动终端和传感器节点之间通过应答和重传的机制来保证数据的可靠传输。仿真研究证明,该协议在延长网络生存时间的同时可以获得较高的数据传输成功率和较短的数据传输延迟,而且可靠性、灵活性、可扩展性较强。     

Data-driven optimal terminal iterative learning control

This paper presents a data-driven optimal terminal iterative learning control (TILC) approach for linear and nonlinear discrete-time systems. The iterative learning control law is updated from only terminal output tracking error instead of entire output trajectory tracking error. The only required knowledge of a controlled system is that the Markov matrices of linear systems or the partial derivatives of nonlinear systems with respect to control inputs are bounded. Rigorous analysis and convergence proof are developed with sufficient conditions for the terminal ILC design and the results are developed for both linear and nonlinear discrete-time systems. Simulation results illustrate the applicability and effectiveness of the proposed approach.     

Performance Monitoring of Remote Websites Using Mobile Agents

In this paper, a mobile agent based approach is investigated to provide the underlying framework for monitoring the performance tests at a remote website. Mobile agents are autonomous and dynamic entities that can migrate between various nodes in the network. They offer many advantages over traditional design methodologies, including: reduction in network load, overcoming network latency and disconnected operations. This research aims to explore the adaptability of the mobile agent approach for website performance testing. It analyses the applicability of mobile agents in carrying out a monitoring task. We have designed and implemented the monitoring framework. The performance of mobile agents is compared with the non-agent approach. Analyzing the results for the same purpose and environments, the mobile agent approach performs better in reducing the load on the host server and saving communication bandwidth than the traditional approaches.     

基于电力现场校验系统的移动终端设计

传统的电力移动终端面对现今多种通信网络,存在多通信网自适切换应能力不足的情况。为此,设计基于电力现场的校验系统的移动终端设计。在原有移动终端的基础上,选择TU-30作为GPS模块的核心模块,实现对电力现场的定位,设计移动网络和WiFi网络融合的通信模块,并修改原有的供电电路,防止供电电压过低,利用电力现场校验系统处理现场校验数据,通过XMPP协议和Openfire服务器实现移动终端的通信功能,至此基于电力现场校验系统的移动终端设计完成。测试结果表明:与传统的电力移动终端相比,设计的基于电力现场校验系统的移动终端多通信网自适应切换时间缩短了3倍左右,大大提高了多通信网自适应切换能力。     

Location and Configuration Management in Mobile-Switch ATM Networks

The features of two important application scenarios, supporting mobile switches with fixed end users and mobile switches with mobile users, are dramatically different from those of the traditional wired network structure. To exploit mobile switches, the location and configuration management of mobile switches is essential to handle the mobility and topology change of the wireless/mobile ATM network. In this paper we address the location management and configuration problems of mobile switches in an ATM network. We investigate several aspects of the location management problem including architecture to support switch mobility, mobile switch tracking, and mobile switch locating. We propose an approach that is based on the Private Network-Network Interface (PNNI) protocol. We extend the PNNI protocol to enable it to handle mobile switches. Moreover, we develop analytical models to determine the tracking and locating costs for mobile switches under the proposed scheme. The models illustrate the relation between total cost (tracking cost + locating cost) and peer group size. The models can be used to derive the optimal configuration for an ATM network with mobile switches.     

神经网络PID 控制的机器人视觉反馈跟踪

探讨针对视觉空间的非完整移动机器人的跟踪控制问题。在不校准摄像机视觉参数的情况下,利用视觉反馈得到的信息,设计出非完整移动机器人轨迹跟踪的神经网络控制器。将BP网络与PID控制相结合,避免复杂的公式推导,解决参数不校准下的控制问题,并很好的实现跟踪。仿真结果证明了文中方法的有效性。     

A grid-based coverage approach for target tracking in hybrid sensor networks

Most existing work on the coverage problem of wireless sensor networks focuses on improving the coverage of the whole sensing field. In target tracking, the interested coverage area is the emerging region of a motorized target, not the whole sensing field. As the motorized target moves, the emerging region is also dynamically changed. In this paper, we propose a grid-based and distributed approach for providing large coverage for a motorized target in a hybrid sensor network. The large coverage is achieved by moving mobile sensor nodes in the network. To minimize total movement cost, the proposed approach needs to solve the following problems: the minimum number of mobile sensor nodes used for healing coverage holes and the best matching between mobile sensor nodes and coverage holes. In the proposed approach, the above two problems are first transformed into the modified circle covering and minimum cost flow problems, respectively. Then, two polynomial-time algorithms are presented to efficiently solve these two modified graph problems, respectively. Finally, we perform simulation experiments to show the effectiveness of proposed approach in providing the coverage for a motorized target in a hybrid sensor network.     

Transparent and scalable terminal mobility for vehicular networks

Future public transportation systems will provide broadband access to passengers, carrying legacy terminals with 802.11 connectivity. Passengers will be able to communicate with the Internet and with each other, while connected to 802.11 Access Points deployed in vehicles and bus stops/metro stations, and without requiring special mobility or routing protocols to run in their terminals. Existing solutions, such as 802.11s and OLSR, are not efficient and do not scale to large networks, thereby requiring the network to be segmented in many small areas, causing the terminals to change IP address when moving between areas.This paper presents WiMetroNet, a large mesh network of mobile routers (Rbridges) operating at layer 2.5 over heterogeneous wireless technologies. This architecture contains an efficient user plane that optimizes the transport of DHCP and ARP traffic, and provides a transparent terminal mobility solution using techniques that minimize the routing overhead for large networks. We offer two techniques to reduce routing overhead associated with terminal mobility. One approach is based on TTL-limited flooding of a routing message and on the concept of forwarding packets only to the vicinity of the last known location of the terminal, and then forward the packets to a new location of the terminal. The other technique lets the network remain unaware for a very long time that the terminal has moved; only when packets arrive at the old PoA does the PoA send back a “binding update” message to the correspondent node, to correct the route for future packets for the same terminal.Simulation and analytical results are presented, and the routing protocol is shown to scale to large networks with good user plane results, namely packet delivery rate, delay, and handover interruption time.     

Nonsingular Terminal Sliding Mode Control of Robot Manipulators Using Fuzzy Wavelet Networks

This paper presents an adaptive nonsingular terminal sliding mode (NTSM) tracking control design for robotic systems using fuzzy wavelet networks. Compared with linear hyperplane-based sliding control, terminal sliding mode controller can provide faster convergence and higher precision control. Therefore, a terminal sliding controller combined with the fuzzy wavelet network, which can accurately approximate unknown dynamics of robotic systems by using an adaptive learning algorithm, is an attractive control approach for robots. In addition, the proposed learning algorithm can on-line tune parameters of dilation and translation of fuzzy wavelet basis functions and hidden-to-output weights. Therefore, a robust control law is used to eliminate uncertainties including the inevitable approximation errors resulted from the finite number of fuzzy wavelet basis functions. The proposed controller requires no prior knowledge about the dynamics of the robot and no off-line learning phase. Moreover, both tracking performance and stability of the closed-loop robotic system can be guaranteed by Lyapunov theory. Finally, the effectiveness of the fuzzy wavelet network-based control approach is illustrated through comparative simulations on a six-link robot manipulator     

Ad Hoc网络安全密钥管理服务

ad hoc网络是一种移动无线自组织网络，与传统有线网络和一般无线网络存在着很大区别。该文分析了ad hoc网络面临的主要安全问题，阐述了目前研究的ad hoc网络安全密钥管理方案，并比较了其优缺点、适用性。