1-hop Neighbor Nodes Research Articles

A Time Synchronization Protocol for Barrage Relay Networks

Time-division multiple access (TDMA)-based medium access control (MAC) protocol has been widely used for avoiding access conflicts in wireless multi-hop ad hoc networks, where the time synchronization among wireless nodes is essential. In this paper, we propose a novel time synchronization protocol for TDMA-based cooperative multi-hop wireless ad hoc networks, which are also called barrage relay networks (BRNs). The proposed time synchronization protocol is based on cooperative relay transmissions to send time synchronization messages. We also propose a network time reference (NTR) selection technique for improving the convergence time and average time error. In the proposed NTR selection technique, each node overhears the user identifier (UID) of other nodes, hop count (HC) from them to itself, and network degree, which denotes the number of 1-hop neighbor nodes. Then, the node with the minimum HC from all other nodes is selected as the NTR node. If there are multiple nodes with the minimum HC, the node with the larger degree is selected as the NTR node. To the best of our knowledge, the proposed time synchronization protocol with the NTR selection is introduced for the first time for cooperative (barrage) relay networks in this paper. Through computer simulations, we validate the proposed time synchronization protocol in terms of the average time error under various practical network scenarios. Furthermore, we also compare the performance of the proposed protocol with the conventional time synchronization methods. It is shown that the proposed protocol significantly outperforms the conventional methods in terms of the average time error and convergence time. The proposed protocol is shown to be more robust against packet loss as well.

Robust and Cooperative Localization for Underwater Sensor Networks in the Existence of Malicious Anchors.

Precise and robust localization in three-dimensional underwater sensor networks is still an important research problem. This problem is particularly challenging if there are some malicious anchors among ordinary anchor nodes that will broadcast their locations falsely and deliberately. In this paper, we study how to self-localize large teams of underwater sensor nodes under the condition that some malicious anchor nodes mixed with ordinary anchors. Due to malicious characteristic of some deliberate anchor nodes, an iterative and cooperative 3D-localization algorithm for underwater sensor networks in the existence of malicious anchors is proposed in this paper. The proposed robust localization algorithm takes advantage of distributed reputation voting method within 1-Hop neighboring reference nodes to detect and eliminate malicious anchor nodes. Moreover, one kind of Minimum Mean Squared Error estimation based iterative localization method is applied to determine accurate location information. Additionally, we analyze and prove that our localization algorithm would have a bounded error when the number of malicious anchors is smaller than a certain threshold. Extensive simulation results are provided to demonstrate performance improvements comparing to traditional Minimum Mean Squared Error and Attack Resistant Minimum Mean Squared Error based localization methods in terms of localization accuracy and coverage ratio.

Learning Automaton-Based Neighbor Discovery for Wireless Networks Using Directional Antennas

This letter studies the problem of neighbor discovery (i.e., finding 1-hop neighbor nodes) in a wireless adhoc network, with exclusive use of directional antennas. We model the neighbor discovery process as a learning automaton, operating in a non-stationary learning environment with unknown dynamics. The node learns about its environment from its past observations and adjusts its strategy to achieve a faster discovery rate. The asymptotic behavior of the proposed learning scheme is analyzed and is shown to converge to an equi-probable probability distribution. The proposed scheme achieves significantly faster network-wide neighbor discovery in densely populated networks.

An Energy Efficient Receiver-based Flooding Scheme Using 1-Hop Neighbours Geographical Information for MANETs

Flooding is a fundamental, critical, and indispensable operation to support various applications and protocols in wireless ad hoc networks. The traditional flooding scheme generates excessive redundant packet retransmissions, causing contention and packet collisions, and ultimately wasting limited bandwidth and energy. Some recent flooding schemes that avoid those problems have been studied. They can achieve local optimality and have lower computational complexity. However, drawbacks limit the efficiency of these schemes. In this paper, we propose an efficient flooding protocol that minimizes flooding traffic, leveraging location information of 1-hop neighbor nodes. Our scheme is receiver-based; it does not piggyback any neighbor information. We prove theoretically that the proposed scheme achieves 100 percent deliverability. Simulation shows our scheme to be highly efficient. It consumes less energy, reduces the number of forwarding nodes almost to that of the benchmark, but maintains a high delivery ratio.

An Energy Efficient Receiver-based Flooding Scheme Using 1-Hop Neighbours Geographical Information for MANETs

Flooding is a fundamental, critical, and indispensable operation to support various applications and protocols in wireless ad hoc networks. The traditional flooding scheme generates excessive redundant packet retransmissions, causing contention and packet collisions, and ultimately wasting limited bandwidth and energy. Some recent flooding schemes that avoid those problems have been studied. They can achieve local optimality and have lower computational complexity. However, drawbacks limit the efficiency of these schemes. In this paper, we propose an efficient flooding protocol that minimizes flooding traffic, leveraging location information of 1-hop neighbor nodes. Our scheme is receiver-based; it does not piggyback any neighbor information. We prove theoretically that the proposed scheme achieves 100 percent deliverability. Simulation shows our scheme to be highly efficient. It consumes less energy, reduces the number of forwarding nodes almost to that of the benchmark, but maintains a high delivery ratio.

Preserving Data Privacy During Data Transfer in MANETs

Mobile adhoc networks consists of large number of mobile nodes, and is usually deployed to transfer data from a sender to a receiver using multi-hop routing. The data being transmitted may contain sensitive information, and undesired disclosure of information can lead to launching of various attacks, thus breaching the data privacy. Earlier works achieve data privacy by using approaches such as data transformation and data perturbation. However, these approaches introduce higher overheads and delays. We propose a computational intelligence based data privacy preserving scheme, where rough set theory is used to anonymize the data during data transfer. Data packets are enclosed within capsules that can be opened only by the designated node, thus preventing the undesired leakage of the data. Also, route between a sender and a receiver is changed dynamically by selecting more than one trusted 1-hop neighbor nodes in each routing step. The proposed data privacy preserving scheme is tested by considering different case studies in a MANET deployed for stock market. Theoretical analysis for data privacy is presented in terms of Information Gain by an attacker and Attacker Overhead, and the performance of proposed scheme against some of the attacks is also discussed. The simulation results show the effectiveness of proposed scheme.

A distributed range-free correction vector based localization refinement algorithm

Localization problem is an important and challenging topic in today's wireless sensor networks. In this paper, a novel localization refinement algorithm for LAEP, which is a range-free localization algorithm by using expected hop progress, has been put forward. The proposed localization refinement algorithm, called as CVLR, is based on position correction vectors and can resolve the LAEP's hop-distance ambiguity problem, which can lead to adjacent unknown nodes localized at the same or very close positions. CVLR can make full use of the relative position relationship of 1-hop neighboring nodes (called as CVLR1), or 1-hop and 2-hop neighboring nodes (called as CVLR2), to iteratively refine their localization positions. Furthermore, from localization accuracy and energy dissipation perspective, we optimize the communication process of CVLR2 and propose an energy-efficient improved CVLR. Simulation results show that the localization accuracy of CVLR1, CVLR2, and the improved CVLR are obviously higher than that of LAEP and DV-RND.

Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm.

In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network (WMN) with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation.

Regular Tiling Based Flooding Scheme for Energy Efficiency in Wireless Ad Hoc Networks

Flooding is a fundamental operation in wireless ad hoc networks to propagate control messages in the entire network. The traditional flooding scheme generates excessive packet retransmissions, resource contention, and collisions since every node forwards the packet at least once. Several flooding schemes have been proposed to avoid these problems. However, these unnecessary forwarding nodes remain in these flooding schemes. In this paper, we propose a novel flooding scheme termed Regular Tiling (RT) Based Flooding to efficiently minimize the number of forwarding nodes. It employs a regular tiling method. RT Based Flooding, selects nodes that are located closest to vertices of regular polygon, using location information of 1-hop neighbor nodes, as forwarding nodes. We also provide ideal forwarding models to minimize the number of forwarding nodes and prove that our scheme approaches the ideal model through detailed analysis. Simulation shows that the performance of our scheme outperforms recent noteworthy flooding schemes in terms of the number of forwarding nodes, number of collisions, and delivery ratio.

RSD: A Metric for Achieving Range-Free Localization beyond Connectivity

Wireless sensor networks have been considered as a promising tool for many location-dependent applications. In such deployments, the requirement of low system cost prohibits many range-based methods for sensor node localization; on the other hand, range-free approaches depending only on radio connectivity may underutilize the proximity information embedded in neighborhood sensing. In response to these limitations, this paper introduces a proximity metric called RSD to capture the distance relationships among 1-hop neighboring nodes in a range-free manner. With little overhead, RSD can be conveniently applied as a transparent supporting layer for state-of-the-art connectivity-based localization solutions to achieve better accuracy. We implemented RSD with three well-known algorithms and evaluated using two outdoor test beds: an 850-foot-long linear network with 54 MICAz motes, and a regular 2D network covering an area of 10,000 square feet with 49 motes. Results show that our design helps eliminate estimation ambiguity with a subhop resolution, and reduces localization errors by as much as 35 percent. In addition, simulations confirm its effectiveness for large-scale networks and reveal an interesting feature of robustness under unevenly distributed radio path loss.

Robust Node Localization Based on Distributed Weighted-multidimensional Scaling in Wireless Sensor Networks

This paper focuses on the robustness of node localization in various topological and sparse network. By taking account of the number of 1-hop neighboring nodes, the node position accuracy and the ranging errors, we introduce concepts of node relative localization error and relative reliability, and then propose a robust node localization algorithm based on distributed weighted-multidimensional scaling. It adaptively chooses those neighboring nodes with high relative reliability to join in the node position refinement according to local node density and their relative localization errors within 2 hops, and adopts a weighting scheme proportional to the relative reliability which emphasizes the lowest relative error within the sensor networks. For received signal strength based range measurements, extensive simulation shows that this algorithm can prevent large localization errors from spreading through the networks. Compared with dwMDS (G), this algorithm can decrease iterative times by one half and gain about 5% smaller localization errors in sparse node density or anisotropic topologies.