Mobile Anchor Research Articles

Swarm Intelligence Optimization Techniques for Obstacle-Avoidance Mobility-Assisted Localization in Wireless Sensor Networks

In many applications of wireless sensor networks (WSNs), node location is required to locate the monitored event once occurs. Mobility-assisted localization has emerged as an efficient technique for node localization. It works on optimizing a path planning of a location-aware mobile node, called mobile anchor (MA). The task of the MA is to traverse the area of interest (network) in a way that minimizes the localization error while maximizing the number of successful localized nodes. For simplicity, many path planning models assume that the MA has a sufficient source of energy and time, and the network area is obstacle-free. However, in many real-life applications such assumptions are rare. When the network area includes many obstacles, which need to be avoided, and the MA itself has a limited movement distance that cannot be exceeded, a dynamic movement approach is needed. In this paper, we propose two novel dynamic movement techniques that offer obstacle-avoidance path planning for mobility-assisted localization in WSNs. The movement planning is designed in a real-time using two swarm intelligence based algorithms, namely grey wolf optimizer and whale optimization algorithm. Both of our proposed models, grey wolf optimizer-based path planning and whale optimization algorithm-based path planning, provide superior outcomes in comparison to other existing works in several metrics including both localization ratio and localization error rate.

A novel distributed node searching method in DTNs

Among conventional target tracking methods in delay-tolerant networks (DTNs), there exists a type of distributed approach which is efficient with regard to target tracking. However, some nodes in these methods consume energy too quickly, resulting in energy holes and a short network lifetime. Based on the above, this research developed a novel target track strategy (MAtracking), on the basis of a mobile anchor (MA) and any correlation between nodes. It improves the effect of the target tracking through two new mechanisms: first, a new data collection method (MA), is adopted. Secondly, the correlation between nodes is used to track the target in the absence of valid mobile information about it. A large number of experimental results from real data simulations show that the proposed MAtracking method can improve the network lifetime and tracking efficiency compared with existing approaches.

Securing Locations of Mobile Nodes in Wireless Mesh Network’s

The current deployment of wireless mesh networks requires mobility management to track the current locations of mobile nodes around the network without service interruption. To do so, the Hierarchical Mobile IPv6 protocol has been chosen, which minimises the required signalling by introducing a new entity called the mobile anchor point to act as a local home agent for all visiting mobile nodes in a specific domain. It allows a mobile node to register its local/regional care-of addresses with a mobile anchor point by sending a local binding update message. However, the local binding update is quite sensitive; it modifies the routing to enable mobility in the wireless mesh networks. When a local binding update message is spoofed, an attacker can redirect traffic that is destined for legitimate mobile node either to itself or to another node. This situation leads to an increased risk of attacks. Therefore, this paper contributes to addressing this security issue based on wireless mesh networks by cryptography generation and verification of a mobile node’s local and regional care-of addresses, as well as the application of a novel method to verify the reachability of mobile node at claimed local care-of address. This is called the enhanced mobile anchor point registration protocol. The Scyther tool has been used to ensure the proposed protocol accuracy. Furthermore, the performance, in terms of the mobile anchor point registration delay and signalling overhead, is evaluated by using the OPNET modeller simulator.

Maximizing the Network Life Time of Wireless Sensor Networks Using a Mobile Charger

In Wireless Sensor Networks (WSN) the wireless nodes work untethered and have limited power resource. Wireless charging provides an alternative approach to recharge the batteries of the wireless nodes. Localization provides the position information. Previous works have considered either on recharging techniques or on the localization. This paper proposes a wireless recharging and also localization using a single mobile anchor. First the mobile anchor locates the static node later it receives the battery level. Finally if the battery of the static node is lesser than the threshold limit β, it recharges the static nodes wirelessly. Also the mobile anchor follows an energy efficient path V curve algorithm. The proposed method can handle the dynamic energy demand efficiently.

Neighbor-Aided Localization in Vehicular Networks

We address the problem of localization in vehicular ad hoc networks. Our goal is to leverage vehicle communications and smartphone sensors to improve the overall localization performance. Assuming vehicles are equipped with the IEEE 802.11p wireless interfaces, we employ a two-stage Bayesian filter to track the vehicle’s position: an unscented Kalman filter for heading estimation using smartphone inertial sensors, and a particle filter that fuses vehicle-to-vehicle signal strength measurements received from mobile anchors whose positions are uncertain, with velocity, GPS position, and map information. Our model leads to a robust localization system and is able to provide useful position information even in the absence of GPS data. We evaluate the algorithm performance using real-world measurements collected from four communicating vehicles in an urban scenario, and considering different combinations of location information sources.

Body area network with mobile anchor based localization

Recent technological advancements in sensors enable wireless sensor networks (WSNs) capable of autonomously monitoring and controlling environments. Medical and healthcare systems find a variety of applications with the tremendous growth of WSNs. The wireless body area network (WBAN) is the emerging technology which has high impact on the society and also in the field of medical as well as non-medical sector. This WBAN is a network with a special purpose that has been designed for operating in an autonomous manner and connect the various medical sensors as well as the appliances that are located inside and also outside the human body. The network also enables physicians for monitoring remotely as well as monitoring the vital signs of the patients also provide some real time feedback for the consultations and diagnosis. This WBAN system will offer two other significant advantages which are patient mobility owing to the use of some portable monitoring devices and also a location independent facility of monitoring. By having appealing dimensions this can bring about a set of challenges that will not be normally taken into consideration. It may need a scalable network that will have some heterogeneous traffic of data with a low power consumption in that of the sensor nodes with the integration either in or around the body of networking. In this paper we propose a WBAN system for monitoring health status of military personnel by automatically identifying the locations of sensor nodes. Experimental tests show that the proposed method works efficiently by monitoring the health conditions of military personnel and thus protects the border of a nation from attackers.

Dynamic Fuzzy-Logic Based Path Planning for Mobility-Assisted Localization in Wireless Sensor Networks.

Mobile anchor path planning techniques have provided as an alternative option for node localization in wireless sensor networks (WSNs). In such context, path planning is a movement pattern where a mobile anchor node’s movement is designed in order to achieve a maximum localization ratio possible with a minimum error rate. Typically, the mobility path planning is designed in advance, which is applicable when the mobile anchor has sufficient sources of energy and time. However, when the mobility movement is restricted or limited, a dynamic path planning design is needed. This paper proposes a novel distributed range-free movement mechanism for mobility-assisted localization in WSNs when the mobile anchor’s movement is limited. The designed movement is formed in real-time pattern using a fuzzy-logic approach based on the information received from the network and the nodes’ deployment. Our proposed model, Fuzzy-Logic based Path Planning for mobile anchor-assisted Localization in WSNs (FLPPL), offers superior results in several metrics including both localization accuracy and localization ratio in comparison to other similar works.

Path planning for a group of mobile anchor nodes based on regular triangles in wireless sensor networks

Localization is one of the fundamental issues in Wireless Sensor Networks (WSNs). Recently, various localization methods have been proposed. However, using single anchor node introduces quite long localization delay. Therefore, the path planning problem of a Group of Mobile Anchor Nodes (GMAN) is studied in this paper. First, two path planning schemes named GSCAN and GTURN are proposed. Both GSCAN and GTURN use three mobile anchor nodes which traverse the entire network following the designed trajectory to help nearby unknown nodes with localization. Furthermore, in order to improve localization ratio of unknown nodes, two boundary strategies are proposed to guarantee that the movement trajectories of anchor nodes can cover the whole WSN. Simulation results show that GSCAN and GTURN can achieve better localization performance than LMAT, RPGM and Ou’s in terms of higher localization ratio and lower energy consumption.

Anchor node path planning for localization in wireless sensor networks

Localization is one of the most important challenges of wireless sensor networks because the location information is typically used in other domains such as coverage, deployment, routing, and target tracking. There exist some localization algorithms that facilitate the sensor nodes to locate itself using the mobile anchor node position. Some crucial attempts have been made in the past for optimizing the mobile anchor node trajectory with good accuracy. This paper presents a novel path planning scheme, D-connect, which ensures the localization of all the sensor nodes with minimum trajectory length. The performance of the proposed scheme is evaluated through a series of simulations. Experimental results reveal that the shortest path for traversing the whole area can be traced with the minimum localization error using this method. It also shows that D-connect outperforms the existing methods in terms of the anchor node trajectory length as well as the localization error.

Energy Efficient Dynamic Node Localization Technique in Wireless Sensor Networks

Objective: This paper represents an energy efficient algorithm for localization of nodes in wireless sensor network by the help of a small number of anchor nodes (mobile). It calculates the node distance and node location. Method/Statistical Analysis: A small group of mobile dynamic anchor node is being associated with a powerful GPS receiver, Radio frequency and ultrasonic device. Location information is broadcasted periodically by the mobile anchor node and by trilateration/ multilateration technique, the static node location is calculated. To calculate the approximate position of a sensor node it takes three rounds. Findings: The technique is evaluated with the matlab and result compared with chord selection approach. The simulation result shows that the proposed localization method performs better and efficient than the other localization algorithms. Application/Improvement: The proposed algorithm adopts distance measurement as TDOA technique and static sensor node can localize when it comes into the reception range. The method is applicable location computation based routing, sensing nodes, node signal processing, and for node localization.

New path planning model for mobile anchor-assisted localization in wireless sensor networks

As event detection is one of the main purposes of using wireless sensor networks (WSNs), the nodes location is essential to determine the location of that event when it occurs. Many localization models have been proposed in the literature. One of the solutions is to deploy a set of location-aware nodes, called anchors, to exchange information with the other nodes in order to help estimate their own location. Another promising proposal involves replacing these sets of anchors with only one mobile anchor. While this proposal seems to provide favorable results, it brings new challenges. The main challenge is to find an optimal path for the mobile anchor to follow while taking into account the need to provide highly accurate data and more localizable nodes in less time and with less energy. In this paper, we introduced a new static path planning model for mobile anchor-assisted localization in WSNs. Our proposed model guarantees that all nodes are able to receive the localization information, thus, estimate their own location with higher localization accuracy in comparison to similar static models. Moreover, this model overcomes the problem of collinearity and takes into account the metrics of precision and energy consumption as well as accuracy, localization ratio and the path length of the mobile anchor.

GTMA: Localization in Wireless Sensor Network Based a Group of Tri-Mobile Anchors

Sensors positioning with high accuracy is a fundamental stone in Wireless Sensor Networks (WSNs). In outdoor environment which is hostile and unreachable, mobile anchors method is considered as an appropriate solution for locating unknown nodes. In this case, the key problems are the trajectory mapping and the needed number of mobile anchors. These mobile anchors should travel along the trajectory in order to determine the positions of unknown nodes with minimum localization error. In this paper, a localization algorithm named Group of Tri-Mobile Anchors (GTMA) is proposed, which is based on a group of tri-mobile anchors with adjustable square trajectory in the deployment area. The position of a target node is calculated by Trilateration. Simulation results show that the performance of the proposed algorithm GTMA is better than that of other algorithms adopted one mobile anchor, e.g., HILBERT, LMAT and SPIRAL algorithms. This is clearly evident in both the localization accuracy and trajectory planning.

802.21-Assisted Distributed Mobility Management Solution in Vehicular Networks

Recently, distributed mobility management (DMM) solutions have been proposed to address the drawbacks of centralized mobility management (CMM) solutions. The Internet engineering task force (IETF) has stated that extending and reusing CMM protocols are one of the considerations for DMM solutions design, where it is less faulty and more effective. Therefore, IETF has proposed a network-based DMM solution based on the well-known network-based CMM protocol: Proxy Mobile IPv6 (PMIPv6). However, network-based DMM has marginal improvements over the handover latency and packet loss of PMIPv6. Thus, this paper enhances the handover procedure of network-based DMM using the HO-initiate process and the IEEE 802.21 media-independent handover services. We tackle the issue of binding registration latency by performing the HO-initiate process proactively. Moreover, we mitigate the latency of discovering next access network and candidate mobile anchor access routers (MAARs) with the support of the lower three layers’ information of the mobile user and surrounded MAARs. A neighbors network information container is introduced to store and retrieve the link and network layers’ information of neighboring networks. A candidate access networks cache is defined at the serving-MAAR to decrease the prediction time. Furthermore, we propose a candidate access network selector to facilitate smart handover decision making by using the information of required and available resources in the candidate networks. We derive an analytical expression to evaluate the proposed solution compared with DMM and fast handover for DMM mechanisms. Simulation is also performed to verify the analytical results, where we consider realistic urban and highway environments. Numerical and simulation results prove that the proposed solution decreases 74.61% of the overall handover latency in DMM.

Mobile anchor nodes path planning algorithms using network-density-based clustering in wireless sensor networks

Motivated by the improvement of the localization performance and the utilization rate of virtual beacons in heterogeneous WSNs, in this paper, we propose three Mobile Anchor nodes Path Planning (MAPP) algorithms, namely, IMAPPP-NDC, SMAPP-NDC and MMAPP-NDC. Different from most of the existing MAPP algorithms which divide the region of interest (ROI) into several layers or areas and make mobile anchor nodes traverse the ROI layer by layer or one area after another, the proposed MAPP algorithms combine network-density-based clustering, inter-cluster path planning and intra-cluster path planning together to improve localization performance and the utilization rate of virtual beacons based on the mathematical analysis of the relationship between the communication range r of a sensor node and the side length a of the regular hexagon movement trajectory. In addition, SMAPP-NDC and MMAPP-NDC algorithms employ obstacle avoidance mechanisms to steer clear of obstacles and provide non-collinear beacon points around obstacles.

Anchor Movement Strategy for Conjecture Geometry Based Localization Scheme in Wireless Sensor Network

<p class="Abstract"><em>Abstract</em>—Localization of sensor node with least error is one of the major concern in wireless sensor network as some of the application require sensor node to know their location with high degree of precision. For mobile anchor based localization many of the path planning schemes already developed which includes scan, double scan, Circles & S- Curves. These path planning schemes have some limitations like localization error, Number of sensor nodes covered in the network, Trajectory length of mobile anchor node. This paper represents anchor movement strategy which is based on Scan path, with modifications are made in such a way that it satisfies the requirements of localization scheme. This movement strategy ensures that trajectory of mobile anchor node will minimize localization error and also will cover majority of sensor node in the environment. The localization error yielded by Modified Scan algorithm is in the range of 0.2 to 0.4m which is quite lower than the other existing mentioned path planning strategies producing localization error in the range 0.6 to 1.8m</p><p class="keywords">Keywords—Localization; Mobile anchor node; Wireless sensor network; Modified Scan algorithm</p>

High‐Density Liquid‐Crystalline Polymer Brushes Formed by Surface Segregation and Self‐Assembly

AbstractHigh‐density polymer brushes on substrates exhibit unique properties and functions stemming from the extended conformations due to the surface constraint. To date, such chain organizations have been mostly attained by synthetic strategies of surface‐initiated living polymerization. We show herein a new method to prepare a high‐density polymer brush architecture using surface segregation and self‐assembly of diblock copolymers containing a side‐chain liquid‐crystalline polymer (SCLCP). The surface segregation is attained from a film of an amorphous base polymer (polystyrene, PS) containing a minor amount of a SCLCP‐PS diblock copolymer upon annealing above the glass‐transition temperature. The polystyrene portion of the diblock copolymer can work as a laterally mobile anchor for the favorable self‐assembly on the polystyrene base film.

High-Density Liquid-Crystalline Polymer Brushes Formed by Surface Segregation and Self-Assembly.

High-density polymer brushes on substrates exhibit unique properties and functions stemming from the extended conformations due to the surface constraint. To date, such chain organizations have been mostly attained by synthetic strategies of surface-initiated living polymerization. We show herein a new method to prepare a high-density polymer brush architecture using surface segregation and self-assembly of diblock copolymers containing a side-chain liquid-crystalline polymer (SCLCP). The surface segregation is attained from a film of an amorphous base polymer (polystyrene, PS) containing a minor amount of a SCLCP-PS diblock copolymer upon annealing above the glass-transition temperature. The polystyrene portion of the diblock copolymer can work as a laterally mobile anchor for the favorable self-assembly on the polystyrene base film.

Node-Gosper Curve-Based Unknown Sensor Localization Using Single Mobile Anchor in Wireless Sensor Networks

The node-Gosper curve is a fractal space-filling curve constructed by recursively replacing each node by a seven-segment generator curve. Here, we propose a novel scheme for describing the path of a node-Gosper curve; the scheme can be used to calculate the coordinates of each turning point of the curve efficiently. The node-Gosper curve serves as a routing path for a single mobile anchor to help unknown sensors locate themselves in the wireless sensor network. In our proposed localization method, the mobile anchor travels along the node-Gosper curve, which covers the entire sensing field, and when it reaches the turning points of the node-Gosper curve, it broadcasts its current location to unknown sensors within a preset communication range. Each unknown sensor estimates its location when it receives at least three messages from the mobile anchor from different locations. Experimental results show that the proposed method outperforms several well-known mobile anchor localization methods in terms of localization accuracy and energy consumption.

Path planning algorithms for mobile anchors towards range-free localization

The objective of path planning for a mobile anchor is to find the path of minimum length that the anchor traverses to localize all sensors. The challenge is to design a movement strategy which reduces path length while meeting the requirements of a good range-free localization technique. A novel deterministic movement strategy is proposed in this paper that reduces path length and uses an existing range-free localization scheme which yields good positional accuracy. The mobile anchor moves in a hexagonal pattern to localize all the sensors which form a connected network. We compare performance of our algorithm with an existing path planning algorithm in terms of both path length and localization accuracy. Simulation results show that even in presence of irregular radio propagation, our algorithm achieves full localization. We have proposed another movement strategy for a mobile anchor using same hexagonal pattern to localize all the sensors lying in a rectangular region. Improvement in path length is shown theoretically compared to existing path planning schemes.

Cooperative energy-efficient localization with node lifetime extension in mobile long-thin networks

In this paper, we propose a Cooperative Energy-Efficient Localization Framework (CELF) for power saving in mobile long-thin networks (MLTNs). We use the cycling ad hoc network with fleet cyclists using mobile phones along a common cycling route as an example (our results could be applicable to other scenarios as well, such as the mountaineering party and army troops). As cyclists need to upload their position data and download global fleet information, all power-consuming GPS receivers have to be switched on for obtaining their current locations. In CELF, distributed localization among cyclists without central control is designed to minimize the energy consumption of positioning. To the best of our knowledge, CELF is the first distributed solution for localization which provides the following features: (i) CELF does not rely on costly roadside infrastructures but only employs cyclist-to-cyclist communications; (ii) CELF can supply group members with the up-to-date locations without activating GPS receivers; (iii) CELF can estimate member positions only based on single mobile anchor instead of multiple static anchors. Simulation and experimental results show that CELF outperforms existing works, which can significantly reduce the energy consumption for localization while keeping the positioning accuracy similar to GPS.