Leader Node Research Articles

Tracking control of leader-follower multi-agent systems subject to actuator saturation

This paper addresses the tracking problem of leader-follower multi-agent systems subject to actuator saturation. A leader node or command generator is considered, which generates the desired tracking trajectory. To track such a leader, a new family of scheduled low-and-high-gain feedback controllers is designed for each follower, provided that the linear dynamic mode is asymptotically null controllable with bounded controls, and such control laws rely on the asymptotic property of a class of parametric algebraic Ricatti equations. We show that if the associated undirected graph of the system is connected, with the proposed control law, all the followers can track the leader eventually. A simulation example is finally given to illustrate the performance of the proposed control scheme.

A Novel Approach for Detection of Blackhole Attacks

The MANET (Mobile Adhoc Network) is a wireless distributed network. It is formed by group of autonomous mobile nodes without any infrastructure like access points. Every node of MANET can acts as router as well as host. It has a basic characteristic of dynamic topology, it means nodes can enter and leave network any time. MANET is vulnerable to many security attacks. Black hole attack is most occurred attack in MANET and very hard to detect which is performed on network layer. Black hole attacks are classified into two types. In single black hole attack, one malicious node will change the route of source to destination and wrong path of malicious node will follow. In collaborative black hole attack one malicious node records packet at one end and send to another malicious node at other end. Black hole attacks are active attacks. In this paper, we propose a solution for detecting black hole attack. Our protocol's name is EBAODV (Enhance Black hole AODV). In this approach, leader nodes are used for detecting black hole nodes.

REQUEST+: A framework for efficient processing of region-based queries in sensor networks

In wireless sensor networks, individual sensing values are not reliable due to node failures. The effect of these failures can be reduced by using aggregated values for groups of sensor nodes instead of the individual sensing values. However, most existing works have focused on computing the aggregation of all the nodes without grouping. Only a few approaches dealt with the processing of grouped aggregate queries. However, since groups in their approaches are disjoint, some areas which are not covered by groups cannot be considered, even if the areas are relevant to the user’s interest. In this paper, we propose a new type of queries, region-based queries, and a framework to process region-based queries, called REQUEST+. A region in REQUEST+ is defined as a maximal set of nodes located within a circle having a diameter specified in the query. To efficiently construct a large number of regions covering the entire monitoring area, we build the SEC (Smallest Enclosing Circle) index. Moreover, in order to process a region-based query, we adapt a clustering-based aggregation method, in which there is a leader node for each region. To minimize the communication cost, we formulate an optimal leader selection problem and prove that it is NP-hard. In addition, we transform the problem into the weighted set-cover problem to utilize the algorithm devised for the problem. Finally, we construct a query-initiated routing tree for the communication between the leader and non-leader nodes. In the experimental results, we show that the result of our region-based query is more reliable than that of the query which is based on individual nodes, and our processing method is more energy-efficient than existing methods for processing grouped aggregate queries.

Synchronized output regulation of switching networks based on synchronization observer

This paper studies the synchronized output regulation (SOR) problem of networked dynamic systems with switching topology that is uniformly connected and leader-rooted. In these networked systems, the tracked signal or the rejected disturbance is generated by the same exosystem, and however, the state of the exosystem is only available for leader nodes. First, a synchronization observer of the exosystem is proposed in this paper to overcome the difficulty caused by the unavailable state of the exosystem for follower nodes with directed switching information flow. It is shown that the observer state will synchronize to the state of the exosystem. Then, two feedback controllers based on decentralized dynamic error and state are presented to solve this SOR problem. Furthermore, the main idea in this paper will provide a promising way for realizing the multirobot systems’ tracking and formation requirement. Numerical simulation results are presented to demonstrate the effectiveness of the theoretical results.

Improved Enhanced Chain Based Energy Efficient Wireless Sensor Network

In this paper, we have proposed an energy efficient chain based protocol which is an improvement over ECBSN (Energy Efficient Chain Based Sensor Network). ECBSN protocol has certain deficiencies like the non optimal selection of leader nodes in rounds, aggregation and transmission of data by head nodes that leads to unbalanced energy consumption. Aiming at these problems, an improved chain based protocol is proposed. IECBSN adopts a new method of selection of leader nodes based on selection value (SV) parameter .To lower energy consumption further, one more level of hierarchy has been added with a head leader node, which will aggregate data from the leader nodes and pass it to the base station. IECBSN shows an improvement of 20% - 35% as compare to PEGASIS (Power Efficient Gathering in Sensor Information System) and 5% t to 7% from ECBSN on energy consumption and improves network lifetime.

Classification of Selfish and Regular Nodes Based on Reputation Values in MANET Using Adaptive Decision Boundary

A MANET is a cooperative network in which each node has dual responsibilities of forwarding and routing thus node strength is a major factor because a lesser number of nodes reduces network performance. The existing reputation based methods have limitation due to their stricter punishment strategy because they isolate nodes from network participation having lesser reputation value and thus reduce the total strength of nodes in a network. In this paper we have proposed a mathematical model for the classification of nodes in MANETs using adaptive decision boundary. This model classifies nodes in two classes: selfish and regular node as well as it assigns the grade to individual nodes. The grade is computed by counting how many passes are required to classify a node and it is used to define the punishment strategy as well as enhances the reputation definition of traditional reputation based mechanisms. Our work provides the extent of noncooperation that a network can allow depending on the current strength of nodes for the given scenario and thus includes selfish nodes in network participation with warning messages. We have taken a leader node for reputation calculation and classification which saves energy of other nodes as energy is a major challenge of MANET. The leader node finally sends the warning message to low grade nodes and broadcasts the classification list in the MANET that is considered in the routing activity.

A Chain Routing Algorithm Based on Traffic Prediction in Wireless Sensor Networks

As a representative of chain-based protocol in Wireless Sensor Networks (WSNs), EEPB is an elegant solution on energy efficiency. However, in the latter part of the operation of the network, there is still a big problem: reserving energy of the node frequently presents the incapacity of directly communicating with the base station, at the same time capacity of data acquisition and transmission as normal nodes. If these nodes were selected as LEADER nodes, that will accelerate the death process and unevenness of energy consumption distribution among nodes.This paper proposed a chain routing algorithm based ontraffic prediction model (CRTP).The novel algorithmdesigns a threshold judgment method through introducing the traffic prediction model in the process of election of LEADER node. The process can be dynamically adjusted according to the flow forecasting. Therefore, this algorithm lets the energy consumption tend-ing to keep at same level. Simulation results show that CRTP has superior performance over EEPB in terms of balanced network energy consumption and the prolonged network life.

A Chain-Based Routing Protocol to Maximize the Lifetime of Wireless Sensor Networks

Energy conservation is a key issue in the design of systems based on wireless sensor networks. Clustering routing protocols have been developed in order to reduce the network traffic toward the sink and therefore prolong the network lifetime. An alternative of clustering is to build chains instead of clusters. In this context, we propose a routing protocol for Wireless Sensor Networks (WSN). It is based on constructing multiple chains in the direction of the sink. The first node of each chain sends data to the closest node in the same chain. This latter collects, aggregates and transmits data to the next closest node. This process repeats until reaching the last node, which aggregates and transmits data directly to the sink. An improvement of this approach is proposed. It works as follows: In addition to forming multiple chains as previously, it constructs a main chain, which includes leader node of each chain. Since, initially all main chain nodes have the same amount of power, the nearest node to the sink aggregates data from others then transmits it to the sink. In the next transmission, main chain node having the higher residual energy performs this task. Compared with the first approach, simulation results show that improvement approach consumes less energy and effectively extends the network lifetime.

Decentralized Cooperative TOA/AOA Target Tracking for Hierarchical Wireless Sensor Networks

This paper proposes a distributed method for cooperative target tracking in hierarchical wireless sensor networks. The concept of leader-based information processing is conducted to achieve object positioning, considering a cluster-based network topology. Random timers and local information are applied to adaptively select a sub-cluster for the localization task. The proposed energy-efficient tracking algorithm allows each sub-cluster member to locally estimate the target position with a Bayesian filtering framework and a neural networking model, and further performs estimation fusion in the leader node with the covariance intersection algorithm. This paper evaluates the merits and trade-offs of the protocol design towards developing more efficient and practical algorithms for object position estimation.

A Novel Leader based Reputation Approach for Mobile Ad Hoc Networks

Mobile ad hoc networks perform well only when nodes in the network cooperate in routing and packet forwarding. As these networks are lack of security aspects, selfish and malicious nodes become a part of that network resulting in performance degradation. This paper suggests a leader based reputation system for identifying routing misbehavior. The reputation system is constructed using trust value and decision made in routing that are based on past experience, observations and/ or informed behavior of other nodes. Trust value is evaluated using trust resilient algorithm and it is based on two important parameters namely, efficacy factor and feedback reliability. A node with high battery life and high trust value is elected as a leader. The member nodes report the reputation value and feedback to the leader. The leader node maintains a reputation and feedback records of all its member nodes. The reputation value is an integer value and feedback is just a phrase conveying the satisfaction level of performance of a node. A node with continuous negative feedback is treated as a malicious node and isolated from the network. Feedback is aggregated using modified periodic per hop adaptive aggregation techniques. This proposal detects a malicious node effectively and avoids false reporting as it considers only feedback from the highly reputed node. We perform an overall analysis of our paper by simulation using the network simulator (NS2). The experimental results clearly indicate the effectiveness and advantages of our proposed system in eliminating misbehaving nodes.

Enhanced Bully Algorithm for Leader Node Election in Synchronous Distributed Systems

In distributed computing systems, if an elected leader node fails, the other nodes of the system need to elect another leader. The bully algorithm is a classical approach for electing a leader in a synchronous distributed computing system. This paper presents an enhancement of the bully algorithm, requiring less time complexity and minimum message passing. This significant gain has been achieved by introducing node sets and tie breaker time. The latter provides a possible solution to simultaneous elections initiated by different nodes. In comparison with the classical algorithm and its existing modifications, this proposal generates minimum messages, stops redundant elections, and maintains fault-tolerant behaviour of the system.

Adaptive cooperative tracking control of higher-order nonlinear systems with unknown dynamics

A practical design method is developed for cooperative tracking control of higher-order nonlinear systems with a dynamic leader. The communication network is a weighted directed graph with a fixed topology. Each follower node is modeled by a higher-order integrator incorporating with unknown nonlinear dynamics and an unknown disturbance. The leader node is modeled as a higher-order nonautonomous nonlinear system. It acts as a command generator giving commands only to a small portion of the networked group. A robust adaptive neural network controller is designed for each follower node such that all follower nodes ultimately synchronize to the leader node with bounded residual errors. Moreover, these controllers are distributed in the sense that the controller design for each follower node only requires relative state information between itself and its neighbors. A simulation example demonstrates the effectiveness of the algorithm.

Study of various Election algorithms on the basis of messagepassing approach

An important challenge in distributed systems is the adoption of suitable and efficient algorithms for coordination selection. The leader election is important problem in distributed system as data is distributed among different node which is geographically separate. For maintaining co-ordination between the node, leader node have to be selected. The main role of an elected coordinator is to manage the use of shared resources in optimal manner. This paper represents the different election algorithms with their limitations as well comparative analysis of them, efficiency in terms of number of messages exchanged in each case and the complexity of various coordinator selection algorithms in distributed systems.

Energy Efficient Target Tracking with Particle Filtering Techmique in Wireless Sensor Networks

In this study, a new target tracking algorithm is proposed for wireless sensor networks. The aim of the algorithm is to decrease energy consumption of the system by decreasing the ratio of target misses. Next location of the target is predicted by using Particle Filtering (PF) technique which aims to represent the posterior density function by a set of random samples with associated weights. Nodes are deployed according to the hexagon shaped network topology in which each of the hexagons represents a cluster with a predetermined leader node. In order to decrease the ratio of target misses, nodes that are closer to the target's predicted location are woken up to make them ready to detect the target. This increases the probability of detecting the target by one of the neighboring hexagons when the target makes sudden turns or unexpected movements. Tracking performance of the proposed algorithm is evaluated by comparing with KNearest Cluster Tracking (KNCT), Wakening Based Target Tracking Algorithm (WBTA)[10] and Generic Static Tracking Approach (GSTA) in terms of miss ratio and energy consumption metrics.

Analysis of error propagation in particle filters with approximation

This paper examines the impact of approximation steps that become necessary when particle filters are implemented on resource-constrained platforms. We consider particle filters that perform intermittent approximation, either by subsampling the particles or by generating a parametric approximation. For such algorithms, we derive time-uniform bounds on the weak-sense $L_p$ error and present associated exponential inequalities. We motivate the theoretical analysis by considering the leader node particle filter and present numerical experiments exploring its performance and the relationship to the error bounds.

Optimal Design for Synchronization of Cooperative Systems: State Feedback, Observer and Output Feedback

This technical note studies synchronization of identical general linear systems on a digraph containing a spanning tree. A leader node or command generator is considered, which generates the desired tracking trajectory. A framework for cooperative tracking control is proposed, including full state feedback control, observer design and dynamic output feedback control. The classical system theory notion of duality is extended to networked systems. It is shown that unbounded synchronization regions that achieve synchronization on arbitrary digraphs containing a spanning tree can be guaranteed by using linear quadratic regulator based optimal control and observer design methods at each node.

SmartMote: An Adaptive Update Mechanism for Wireless Ad-Hoc Sensor Network

This paper describes a novel update mechanism for large wireless ad-hoc sensor networks (WASNs). In wireless sensor networks, the nodes may have to be reprogrammed, especially for design-implement-test iterations. Manually reprogramming is a very cumbersome work, and may be infeasible if nodes of the network are unreachable. In addition, replacing the executed application on a node by transmitting the complete program image is inefficient for small changes in the code either. It consumes a lot of bandwidth and time. Therefore, an on-the-fly update mechanism is required. This paper exploits programmable packets to update sensor behaviors. To reduce the code transferred and power consumption, a group management architecture is developed. This architecture helps reduce power consumption and increase node number that control by Leader Node in WASNs. The proposed update mechanism, SmartMote, has been implemented on the Tmote-based Octopus II sensor node. Performance evaluation as well as measurement is conducted in the paper to illustrate the significance of the proposed mechanism.

Leader election on tree-based centrality in ad hoc networks

A leader in a network plays important roles for various services of the network and controls problems of the network. Therefore, when the nodes with high centrality are selected as the leader nodes in the network, the network can be more efficiently controlled, and the amount of wasted resources can be reduced. In this study, we propose a novel method for determining leader nodes by measuring centrality of nodes in the ad hoc networks. The proposed method can obtain the centrality of each node using the average depth of nodes based on the tree topology. Consequently, the amount of the information required for leader election becomes smaller and the calculation process is also simpler, compared with those of representative centrality methods in social network analysis (SNA). In the experiment, the proposed tree-based centrality technique is compared with the well-known centrality schemes such as degree, closeness, and betweenness. The proposed tree-based centrality method has similar centrality priority as degree, closeness, and betweenness and also has better performance in the comparison of the control messages generated.

A Multi-Hop Weighted Clustering of Homogeneous MANETs Using Combined Closeness Index

In this paper, a new multi-hop weighted clustering procedure is proposed for homogeneous Mobile Ad hoc networks. The algorithm generates double star embedded non-overlapping cluster structures, where each cluster is managed by a leader node and a substitute for the leader node (in case of failure of leader node). The weight of a node is a linear combination of six different graph theoretic parameters which deal with the communication capability of a node both in terms of quality and quantity, the relative closeness relationship between network nodes and the maximum and average distance traversed by a node for effective communication. This paper deals with the design and analysis of the algorithm and some of the graph theoretic/structural properties of the clusters obtained are also discussed.

Influence of Node Dynamics on Cluster Global Time Continuity

The cluster global time can change in wireless sensor networks due to leader re-elections and node disabilities between two successive synchronizations, which will affect temporal relationships. This paper analyzes cluster global time continuity, using global time change models for the node dynamics. The results prove that defining the global time using the cluster average time (AGT) is more stable than defining it using a single node's local time (SGT). With normally distributed clock-parameter assumptions, the AGT change bounds are at most 70.7% of those for the SGT's. The impacts of the initial phase and frequency skew distributions on the global time continuity are also investigated to show that the initial phase variations may strongly influence the continuity. Simulations show that the AGT is more stable with less disabled nodes or larger clusters. The appropriate cluster size is 20–40 when there are less than 15 disabled nodes.