MAP: Design and implementation of a mobile agents' platform

The recent development of telecommunication networks has contributed to the success of applications such as information retrieval and electronic commerce, as well as all the services that take advantage of communication in distributed systems. In this area, the emerging technology of mobile agents aroused considerable interest. Mobile agents are applications that can move through the network for carrying out a given task on behalf of the user. In this work we present a platform called MAP (Mobile Agents Platform) for the development and the management of mobile agents. The language used both for developing the platform and for carrying out the agents is Java. The platform gives the user all the basic tools needed for creating some applications based on the use of agents. It enables us to create, run, suspend, resume, deactivate, reactivate local agents, to stop their execution, to make them communicate each other and migrate.     

Robot and sensor networks for first responders

The need to collect, integrate, and communicate information effectively in emergency response scenarios exceeds the state of the art in information technology. This emergency response problem provides an interesting and important test bed for studying networks of distributed mobile robots and sensors. Here, we describe the component technologies required to deploy a networked-robot system that can augment human firefighters and first responders, significantly enhancing their firefighting capabilities. In a burning building at a firefighting training facility, we deployed a network of stationary Mote sensors, mobile robots with cameras, and stationary radio tags to test their ability to guide firefighters to targets and warn them of potential dangers. Our long-term vision is a physical network that can sense, move, compute, and reason, letting network users (firefighters and first responders) Google for physical information - that is, information about the location and properties of physical objects in the real world.     

Low-cost checkpointing and failure recovery in mobile computingsystems

A mobile computing system consists of mobile and stationary nodes, connected to each other by a communication network. The presence of mobile nodes in the system places constraints on the permissible energy consumption and available communication bandwidth. To minimize the lost computation during recovery from node failures, periodic collection of a consistent snapshot of the system (checkpoint) is required. Locating mobile nodes contributes to the checkpointing and recovery costs. Synchronous snapshot collection algorithms, designed for static networks, either force every node in the system to take a new local snapshot, or block the underlying computation during snapshot collection. Hence, they are not suitable for mobile computing systems. If nodes take their local checkpoints independently in an uncoordinated manner, each node may have to store multiple local checkpoints in stable storage. This is not suitable for mobile nodes as they have small memory. This paper presents a synchronous snapshot collection algorithm for mobile systems that neither forces every node to take a local snapshot, nor blocks the underlying computation during snapshot collection. If a node initiates snapshot collection, local snapshots of only those nodes that have directly or transitively affected the initiator since their last snapshots need to be taken. We prove that the global snapshot collection terminates within a finite time of its invocation and the collected global snapshot is consistent. We also propose a minimal rollback/recovery algorithm in which the computation at a node is rolled back only if it depends on operations that have been undone due to the failure of node(s). Both the algorithms have low communication and storage overheads and meet the low energy consumption and low bandwidth constraints of mobile computing systems     

Communication facilities for distributed transaction-processingsystems

The study of communication designs in the context of the Raid system, a robust and adaptable distributed database system for transaction processing, is discussed. Related research work on local interprocess communication, remote interprocess communication, and communication protocols for both local area and wide area networks is briefly summarized. A series of experiments on the performance of the facilities available for building the Raid communication software is described. Raid's communication software, called Raidcomm, has evolved as a result of the knowledge gained both from other systems and from the authors' experiments. Several communication services and mechanisms that can be used to make Raid efficient are identified     

Using mobile agents to recover from node and database compromise in path-based DoS attacks in wireless sensor networks

Wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop end-to-end communication path with either replayed packets or injected spurious packets. Detection and recovery from PDoS attacks have not been given much attention in the literature. In this article, we consider wireless sensor networks designed to collect and store data. In a path-based attack, both sensor nodes and the database containing collected data can be compromised. We propose a recovery method using mobile agents which can detect PDoS attacks easily and efficiently and recover the compromised nodes along with the database.     

Key distribution scheme for peer-to-peer communication in mobile underwater wireless sensor networks

Wireless Sensor Networks (WSN) consist of small battery-limited devices called sensor nodes. The communication between sensor nodes is a type of peer-to-peer communication, since each node has the same capability and role. One of the recent application areas of these nodes is underwater sensing. Communication in Underwater Wireless Sensor Networks (UWSN) is challenging since radio frequencies cannot be used. Instead acoustic waves, which cause extra challenges, are used in UWSN. Since UWSNs are deployed in hostile environment, nodes can be captured by an adversary. In order to secure UWSNs, key distribution problem must be addressed. Moreover, UWSNs are inherently mobile since the nodes may be drifted in the sea. In this paper, we propose a key distribution model which is applied for two group mobility models, namely nomadic mobility model and meandering mobility model. In both schemes hierarchical structure is used and communication is handled via well-known Blom’s key distribution scheme. Our simulation results show that mobility causes some temporary decreases in the connectivity, but our schemes help to heal the connectivity performance in time. Moreover, our schemes show good resiliency performance such that capture of some nodes by an adversary only causes very small amount of links between uncaptured nodes to be compromised.     

A virtual infrastructure for large-scale wireless sensor networks

The primary goal of a wireless sensor network is to collect useful information from the network. Most wireless sensor networks are assumed that the number of nodes are very large and they should operate with confined resources. Consequently it is important to take a scalable and energy-efficient architecture.In this paper, we present Railroad, a data collection and topology management architecture for large-scale wireless sensor networks. It proactively exploits a virtual infrastructure called Rail, which acts as a rendezvous area of the event data and queries. By using Rail, Railroad achieves scalability and energy efficiency under dynamic conditions with multiple mobile observers and targets. We evaluate the communication cost and the hot area message complexity of Railroad and compare them with previous approaches. We evaluate communication cost of Railroad by both an analytic model and simulations.     

动态传感器网络区域受限的移动sink路径选择研究

针对sink区域受限及节点特征参数的问题,如何规划sink路径选择以满足动态传感器网络高效数据收集及低能耗的要求,提出了一种动态传感器网络区域受限的移动sink路径选择方法。该方法在缓存节点辅助通信模式下,建立sink受限区域图模型。针对不同应用情况,分别讨论了sink移动全局路径信息已知和sink移动局部路径信息已知这两种情况下的最优移动路径。在全局路径信息已知时,采用Vornon单元划分的思想求解总传输能耗和节点平均负载;在局部路径信息已知时,采用启发式策略进行路径寻优,并证明其路径寻优的正确性。最后通过仿真实验与理论计算来验证移动sink最佳路径寻优策略的有效性和可行性。     

An efficient homomorphic MAC-based scheme against data and tag pollution attacks in network coding-enabled wireless networks

Recent research efforts have shown that wireless networks can benefit from network coding (NC) technology in terms of bandwidth, robustness to packet losses, delay and energy consumption. However, NC-enabled wireless networks are susceptible to a severe security threat, known as data pollution attack, where a malicious node injects into the network polluted packets that prevent the destination nodes from decoding correctly. Due to recoding, occurred at the intermediate nodes, according to the core principle of NC, the polluted packets propagate quickly into other packets and corrupt bunches of legitimate packets leading to network resource waste. Hence, a lot of research effort has been devoted to schemes against data pollution attacks. Homomorphic MAC-based schemes are a promising solution against data pollution attacks. However, most of them are susceptible to a new type of pollution attack, called tag pollution attack, where an adversary node randomly modifies tags appended to the end of the transmitted packets. Therefore, in this paper, we propose an efficient homomorphic message authentication code-based scheme, called HMAC, providing resistance against data pollution attacks and tag pollution attacks in NC-enabled wireless networks. Our proposed scheme makes use of three types of homomorphic tags (i.e., MACs, D-MACs and one signature) which are appended to the end of the coded packet. Our results show that the proposed HMAC scheme is more efficient compared to other competitive tag pollution immune schemes in terms of complexity, communication overhead and key storage overhead.     

防止移动Agent通信失效的方法

通信机制是移动代理系统研究的关键技术之一,但是由于Agent具有移动性,使得Agent在通信过程中会引起通信失效问题.在比较了几种防止通信失效的方法后,结合集中式控制和本地通信,提出了一种新的防止移动Agent通信失效的方法,在有效控制通信开销的同时,保证了消息传递的可靠性.     

CAMAS: A cluster-aware multiagent system for attributed graph clustering

Attributed graphs describe nodes via attribute vectors and also relationships between different nodes via edges. To partition nodes into clusters with tighter correlations, an effective way is applying clustering techniques on attributed graphs based on various criteria such as node connectivity and/or attribute similarity. Even though clusters typically form around nodes with tight edges and similar attributes, existing methods have only focused on one of these two data modalities. In this paper, we comprehend each node as an autonomous agent and develop an accurate and scalable multiagent system for extracting overlapping clusters in attributed graphs. First, a kernel function with a tunable bandwidth factor δ is introduced to measure the influence of each agent, and those agents with highest local influence can be viewed as the “leader” agents. Then, a novel local expansion strategy is proposed, which can be applied by each leader agent to absorb the most relevant followers in the graph. Finally, we design the cluster-aware multiagent system (CAMAS), in which agents communicate with each other freely under an efficient communication mechanism. Using the proposed multiagent system, we are able to uncover the optimal overlapping cluster configuration, i.e. nodes within one cluster are not only connected closely with each other but also with similar attributes. Our method is highly efficient, and the computational time is shown that nearly linearly dependent on the number of edges when δ ∈ [0.5, 1). Finally, applications of the proposed method on a variety of synthetic benchmark graphs and real-life attributed graphs are demonstrated to verify the systematic performance.     

Algorithms for energy-driven agent placement in wireless embedded systems with memory constraints

The agent programming paradigm provides an easy to use framework for coding embedded applications in a pervasive environment. Under this model, applications are structured as mobile agents that can be flexibly installed on the available nodes of the system. Typically, such system nodes have limitations concerning battery and memory resources. The agent placement problem (APP) we consider in this paper, consists of deciding which agents should be placed at which nodes, in order to maximize the lifetime of the first node that runs out of battery. Since wireless communication has been identified in the past as a primary source of energy consumption, APP essentially involves bringing communicating agents close to each other, thus reducing communication costs. Nevertheless, this cannot always be done due to memory constraints. In fact as more and more agents are installed at the nodes finding free space at any node, let alone the desired one communication-wise, becomes hard. In this paper we tackle the problem of placing a newcomer agent in a stepwise fashion. First, enough memory space must be found or created at some node to place the agent. Second, the placement must be altered in order to make it energy efficient. We present algorithms that tackle each of the above steps separately as well as branch and bound methods for achieving both goals simultaneously. Our algorithms are centralized assuming a single entry point through which agents are injected into the system, with adequate knowledge of the system state and enough resources to run the proposed algorithms. The algorithms are evaluated under different simulated scenarios, and useful tradeoffs are identified.     

Anonymous Geo-Forwarding in MANETs through Location Cloaking

In this paper, we address the problem of destination anonymity for applications in mobile ad hoc networks where geographic information is ready for use in both ad hoc routing and Internet services. Geographic forwarding becomes a lightweight routing protocol in favor of the scenarios. Traditionally the anonymity of an entity of interest can be achieved by hiding it among a group of other entities with similar characteristics, i.e., an anonymity set. In mobile ad hoc networks, generating and maintaining an anonymity set for any ad hoc node is challenging because of the node mobility, consequently the dynamic network topology. We propose protocols that use the destination position to generate a geographic area called {em anonymity zone (AZ)}. A packet for a destination is delivered to all the nodes in the AZ, which make up the anonymity set. The size of the anonymity set may decrease because nodes are mobile, yet the corresponding anonymity set management is simple. We design techniques to further improve node anonymity and reduce communication overhead. We use analysis and extensive simulation to study the node anonymity and routing performance, and to determine the parameters that most impact the anonymity level that can be achieved by our protocol.     

Markov Chain Analysis of Self-organizing Mobile Nodes

Self-organization of autonomous mobile nodes using bio-inspired algorithms in mobile ad hoc networks (manets) has been presented in earlier work of the authors. In this paper, the convergence speed of our force-based genetic algorithm (called fga) is provided through analysis using homogeneous Markov chains. The fga is run by each mobile node as a topology control mechanism to decide a corresponding node??s next speed and movement direction so that it guides an autonomous mobile node over an unknown geographical area to obtain a uniform node distribution while only using local information. The stochastic behavior of fga, like all ga-based approaches, makes it difficult to analyze the effects that various manet characteristics have on its convergence speed. Metrically transitive homogeneous Markov chains have been used to analyze the convergence of our fga with respect to various communication ranges of mobile nodes and also the number of nodes in various scenarios. The Dobrushin contraction coefficient of ergodicity is used for measuring convergence speed for Markov chain model of our fga. Two different testbed platforms are presented to illustrate effectiveness of our bio-inspired algorithm in terms of area coverage.     

Decentralized Swarm Coordination: A Combined Coverage/Connectivity Approach

Decentralized motion coordination for coverage optimization purposes in mobile sensor networks is the scope of this paper. Coordination is performed based on spatial Voronoi tessellation, while taking into consideration the limited sensing capabilities of the agents. Each node performs an independent optimization in order to increase network??s area coverage via its motion, while it attains information from its current and future Delaunay neighbors. A decentralized algorithm is proposed in order to achieve optimal network??s coverage, based on local information. Connectivity issues are analyzed in detail, while a lower bound on the communication radius of the nodes is derived, in order to attain sufficient information for performing the corresponding optimization. An agent moves inside its region of responsibility in a way that the total area surveyed by the network is a monotonically increasing function of time. The online control action makes the network adaptive to possible changes in the environment.     

Performance analysis of hierarchical group key management integrated with adaptive intrusion detection in mobile ad hoc networks

We develop a mathematical model to quantitatively analyze a scalable region-based hierarchical group key management protocol integrated with intrusion detection to deal with both outsider and insider security attacks for group communication systems (GCSs) in mobile ad hoc networks (MANETs). Our proposed adaptive intrusion detection technique is based on majority voting by nodes in a geographical region to cope with collusion of compromised nodes, with each node preloaded with anomaly-based or misuse-based intrusion detection techniques to diagnose compromised nodes in the same region. When given a set of parameter values characterizing operational and environmental conditions, we identify the optimal intrusion detection rate and the optimal regional area size under which the mean time to security failure of the system is maximized and/or the total communication cost is minimized for GCSs in MANET environments. The tradeoff analysis in performance versus security is useful in identifying and dynamically applying optimal settings to maximize the system lifetime for scalable mobile group applications while satisfying application-specific performance requirements.     

城市灾区无人机网络自适应覆盖优化算法

城市灾区中,地面用户节点的移动特性使得应急网络覆盖成为难题。针对城市灾区移动用户节点的应急网络覆盖优化问题,提出一种无人机网络自适应覆盖优化算法。对布谷鸟搜索算法进行改进,并对目标函数进行优化调整,将城市灾区地面用户节点的移动模型应用于改进的布谷鸟算法模拟中,最终实现对城市灾区重点区域移动用户的自适应覆盖优化。仿真结果表明,所提算法与相同实验环境下的标准布谷鸟算法（CSA）和模拟退火算法（SAA）相比,对重点区域的覆盖率分别提升了2.98个百分点和1.87个百分点。多次实验表明无人机网络的覆盖率、连通性及路径损耗稳定,且随着仿真时间变化,应急网络的性能稳定。证明了该算法不仅能够对城市灾区移动节点提供稳定的动态网络覆盖,有较强的全局以及局部寻优能力且能够更加有效地提高对重点区域的覆盖率。     

STIGMERGY-BASED SYNCHRONIZATION OF A SEQUENCE OF TASKS IN A NETWORK OF ASYNCHRONOUS NODES

Social insects are able to build complex architectural structures in spite of their limited capabilities and simple behaviors. The coordination of various activities within a colony of such insects is performed stigmergically through indirect communication. This article describes a stigmergy-based technique by which a set of mobile agents trigger the execution of a sequence of tasks at every node in a network, in a near synchronous manner. These agents use a concept of an innate task-specific potential, which guides them to initiate the execution of a task at various asynchronously operating nodes of a network, in a synchronous manner. This innate potential maintained within the agent also assists in self-healing. The technique is oblivious to both the number of agents and nodes in the network and, hence, is scalable. The proposed technique was emulated on various real static and dynamic topologies by varying different parameters. The results obtained validate the efficacy of the concept of potential. An implementation using real robots has also been presented to portray the practical viability of the proposed technique.     

A Distributed π-Calculus with Local Areas of Communication

This paper introduces a process calculus designed to capture the phenomenon of names which are known universally but always refer to local information. Our system extends the π-calculus so that a channel name can have within its scope several disjoint local areas. Such a channel name may be used for communication within an area, it may be sent between areas, but it cannot itself be used to transmit information from one area to another. Areas are arranged in a hierarchy of levels, distinguishing for example between a single application, a machine, or a whole network. We give an operational semantics for the calculus, and develop a type system that guarantees the proper use of channels within their local areas. We illustrate with models of an internet service protocol and a pair of distributed agents.     

基于Agent的嵌入式动态协议通信系统

为了扩展嵌入式移动终端的通信能力,使之能够透明地与所处局域网进行直接通信,本文采用嵌入式通信协议构件化思想和Agent技术,建立基于Agent的嵌入式动态协议通信系统框架模型,并给出通信方式与过程,以及针对该模型的协议构件化分解及协议构件服务复合方法,从而为探索普适环境中的嵌入式移动终端与所处局域网进行直接通信提供了一种新方案。通过对嵌入式移动终端从协议服务器动态获取所需的协议服务进行实验分析,验证了该方案的有效性。