Towards Accurate Mobile Sensor Network Localization in Noisy Environments
ABSTRACT:

The node localization problem in mobile sensor networks has received significant attention. Recently, particle filters adapted from robotics have produced good localization accuracies in conventional settings. In spite of these successes, state of the art solutions suffer significantly when used in challenging indoor and mobile environments characterized by a high degree of radio signal irregularity. New solutions are needed to address these challenges. We propose a fuzzy logic-based approach for mobile node localization in challenging environments. Localization is formulated as a fuzzy multi-lateration problem. For sparse networks with few available anchors, we propose a fuzzy grid-prediction scheme. The fuzzy logic-based localization scheme is implemented in a simulator and compared to state of the art solutions. Extensive simulation results demonstrate improvements in the localization accuracy from 20% to 40% when the radio irregularity is high. A hardware implementation running on Epic motes and transported by iRobot mobile hosts confirms simulation results and extends them to the real world.


EXISTING SYSTEM:
Range-based localization methods require an estimate of the distance or angle between two nodes to localize and may operate in both absolute and relative coordinate systems.

Typical drawbacks for these methods include higher computational loads, increased node size, higher energy consumption and increased cost.

It assumes a fixed number of anchors but handles mobility very well. The computation and refining are not suitable for a resource-constrained computation platform like a MicaZ node.

Range-free localization methods are typically used in systems where connectivity is the metric of choice and actual geographic distance is less important. Hop counting is a technique frequently used in these scenarios, where the distance between two nodes is inferred from the number of hops a packet takes and is based on some assumed or measured average hop length.

A major drawback is that it fails in networks with irregular topologies such as those with a concave shape. Mobility incurs large overhead since all hop counts must be refreshed frequently.


PROPOSED SYSTEM:
Fuzzy logic offers an inexpensive and robust way to deal with highly complex and variable models of noisy, uncertain environments. It provides a mechanism to learn about an environment in a way that treats variability consistently.

Fuzzy logic can similarly be applied to localization. Empirical measurements are made between participating anchors in predictable encounters. These measurements are analyzed to produce rules that are used by the fuzzy inference systems, which interpret RSS input from unlocalized nodes and other anchors. The output of this process recovers the actual distance, compensated for variability in the local environment. This basic technique is employed in two constituent subsystems of FUZLOC - the Fuzzy Multilateration System (FMS) and the Fuzzy Grid Prediction System (FGPS).

In our proposed fuzzy logic-based localization system, distances between a mobile sensor node and anchor nodes are fuzzified, and used, subsequently in a Fuzzy Multilateration procedure to obtain a fuzzy location. In case two or more anchors are not available for performing localization using fuzzy multilateration, the sensor node employs a new technique, called fuzzy grid prediction, to obtain a location, albeit imprecise.

In the Fuzzy Grid Prediction method, the node uses ranging information from any available anchor to compute distances to several fictitious “virtual anchors” which are assumed to be located in predetermined grids or quadrants. This allows the node to locate the grid/quadrant in which it is present. In conventional localization schemes, the location of a node is typically represented by two coordinates that uniquely identify a single point within some two-dimensional area. Localization using fuzzy coordinates follows a similar convention. The two dimensional location of a node is represented as a pair (X, Y ), where both X and Y are fuzzy numbers and explained below. However, instead of a single point, the fuzzy location represents an area where the probability of finding the node is highest, as depicted in Figure


MODULES:
·        A FUZZY LOGIC-BASED NODE LOCALIZATION FRAMEWORK Module
·        Fuzzy Multilateration Module
·        Fuzzy Inference Module
·        System Implementation Validation Module


MODULE DESCRIPTION:
A FUZZY LOGIC-BASED NODE LOCALIZATION FRAMEWORK Module

In this module, we develope a scenario with highly irregular radio ranges, typical of harsh indoor or extremely obstructed outdoor environments. The irregularity in the radio range is modeled in these simulators as a degree of irregularity (DoI) parameter. The DoI represents the maximum radio range variation per unit degree change in direction.

We define a harsh environment as one in which the distance between sender and receiver cannot be accurately determined from the RSS alone, due to environmental phenomena such as multipath propagation and interference

For more complete problem formulation we mention that the aforementioned localization techniques assume that given a set of mobile sensor nodes, a subset of nodes, called anchors, know their location in a 2-dimensional plane. Also, nodes and anchors move randomly in the deployment area. Maximum velocity of a node is bounded but the actual velocity is unknown to nodes or anchors. Nodes do not
have any knowledge of the mobility model. Anchors periodically broadcast their locations. All nodes are deployed in a noisy, harsh environment and they do not have any additional sensors except their radios.




Fuzzy Multilateration Module:

We present fuzzy multilateration, a component of our fuzzy inference process, which obtains a node’s location from noisy RSS measurements, using fuzzy rule sets.

Fuzzy Inference Module
We present a fuzzy grid prediction scheme, which optimizes our fuzzy inference process, under conditions of low anchor density. However, in mobile sensor networks with low anchor densities, it might frequently be the case that a node does not have enough anchors for multilateration. To address this problem we extend our fuzzy logic-based localization framework to predict an area, e.g., a cell in a grid, where the node might be. The idea is inspired from cellular systems [21]. We propose to virtualize the anchors, so that a node is within a set of Virtual Anchors at any point in time. A Virtual Anchor is a fictitious anchor which is assumed to located at a known, fixed location in the field of deployment, the distance to which can be found in an approximate way from the node. In FUZLOC, we place virtual anchors at the center of every square cell that the field is divided into, as described below. The key idea is that the nearer a node is to a virtual anchor, the more likely it is that the node can be found in that cell.



System Implementation Validation Module
We perform extensive simulations and compare our solution with to state of the art algorithms, using both real-world and synthetic data.


LITERATURE SURVEY:

1 ) Deploying a wireless sensor network on an active volcano

Authors: Konrad Lorincz , Matt Welsh , Omar Marcillo , Jeff Johnson , Mario Ruiz , Jonathan Lees
Augmenting heavy and power-hungry data collection equipment with lighter, smaller wireless sensor network nodes leads to faster,larger deployments. Arrays comprising dozens of wireless sensor nodes are now possible,allowing scientific studies that aren’t feasible with traditional instrumentation. Designing sensor networks to support volcanic studies requires addressing the high data rates and high data fidelity these studies demand. The authors ’ sensor-network application for volcanic data collection relies on triggered event detection and reliable data retrieval to meet bandwidth and data-quality demands. Wireless sensor networks — in which numerous resource-limited nodes are linked via low-bandwidth wireless radios — have been the focus of intense research during the past few years. Since their conception, they’ve excited a range of scientific communities because of their potential to facilitate data acquisition and scientific studies. Collaborations between computer scientists and other domain scientists have produced networks that can record data at a scale and resolution not previously possible. Taking this progress one step further, wireless sensor networks can potentially advance the pursuit of geophysical studies of volcanic activity. Two years ago, our team of computer scientists at Harvard University began collaborating with volcanologists at the University of North Carolina, the University of New Hampshire, and the Instituto

2) Distressnet: a wireless ad hoc and sensor network architecture for situation management in disaster response

AUTHORS: George, S.M.  Texas A&M Univ., College Station, TX, USA  Wei Zhou ;  Chenji, H. ;  Myounggyu Won ;  Yong Oh Lee ;  Pazarloglou, A. ;  Stoleru, R. ;  Barooah, P.

Situational awareness in a disaster is critical to effective response. Disaster responders require timely delivery of high volumes of accurate data to make correct decisions. To meet these needs, we present DistressNet, an ad hoc wireless architecture that supports disaster response with distributed collaborative sensing, topology-aware routing using a multichannel protocol, and accurate resource localization. Sensing suites use collaborative and distributed mechanisms to optimize data collection and minimize total energy use. Message delivery is aided by novel topology management, while congestion is minimized through the use of mediated multichannel radio protocols. Estimation techniques improve localization accuracy in difficult environments.




3) VigilNet: an integrated sensor network system for energy-efficient surveillance

AUTHORS: ian He , Sudha Krishnamurthy , Liqian Luo , Ting Yan , Lin Gu , Radu Stoleru , Gang Zhou , Qing Cao , Pascal Vicaire , John A. Stankovic , Tarek F. Abdelzaher , Jonathan Hui , Bruce Krogh , Tianhe@cs. Umn. Edu S. Krishnamurthy , Liqian Luo , T. Yan , L. Gu , R. Stoleru , G. Zhou , Qing Cao



This article describes one of the major efforts in the sensor network community to build an integrated sensor network system for surveillance missions. The focus of this effort is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. Because of the energy constraints of sensor devices, such systems necessitate an energy-aware design to ensure the longevity of surveillance missions. Solutions proposed recently for this type of system show promising results through simulations. However, the simplified assumptions they make about the system in the simulator often do not hold well in practice, and energy consumption is narrowly accounted for within a single protocol. In this article, we describe the design and implementation of a complete running system, called VigilNet, for energyefficient surveillance. The VigilNet allows a group of cooperating sensor devices to detect and track the positions of moving vehicles in an energy-efficient and stealthy manner. We evaluate VigilNet middleware components and integrated system extensively on a network of 70 MICA2 motes. Our results show that our surveillance strategy is adaptable and achieves a significant extension of

4) Efficient geo-tracking and adaptive routing of mobile assets
AUTHORS:  Balakrishnan, D.  SITE, Univ. of Ottawa, Ottawa, ON, Canada Nayak, A. ;  Dhar, P. ;  Kaul, S.

The recent advancements in technologies such as cellular networks, wireless sensor networks (WSN), radio-frequency identification (RFID), and global positioning system (GPS) have lead us to develop a realistic approach to tracking mobile assets. Tracking and managing the dynamic location of mobile assets is critical for many organizations with mobile resources. Current tracking systems are costly and inefficient over wireless data transmission systems where cost is based on the rate of data being sent. Thus our main research goal is to develop efficient and improved asset tracking solutions and consume valuable mobile resources. In addition, we also adapt their routes by means of a novel and efficient geographical tracking approach that performs route adaptation. We focus on tracking GPS-enabled mobile devices mounted on the asset by understanding the behavior of a mobile device for reporting GPS data in various demographics. This paper is complemented with result evaluations based on a simulation environment with real logs.

5) GPSfree node localization in mobile wireless sensor networks

AUTHORS: Hüseyin Akcan Polytechnic University Vassil Kriakov Polytechnic University Hervé Brönnimann Polytechnic University Alex Delis

An important problem in mobile ad-hoc wireless sensor networks is the localization of individual nodes, i.e., each node's awareness of its position relative to the network. In this paper, we introduce a variant of this problem (directional localization) where each node must be aware of both its position and orientation relative to the network. This variant is especially relevant for the applications in which mobile nodes in a sensor network are required to move in a collaborative manner. Using global positioning systems for localization in large scale sensor networks is not cost effective and may be impractical in enclosed spaces. On the other hand, a set of pre-existing anchors with globally known positions may not always be available. To address these issues, in this work we propose an algorithm for directional node localization based on relative motion of neighboring nodes in an ad-hoc sensor network without an infrastructure of global positioning systems (GPS), anchor points, or even mobile seeds with known locations. Through simulation studies, we demonstrate that our algorithm scales well for large numbers of nodes and provides convergent localization over time, even with errors introduced by motion actuators and distance measurements. Furthermore, based on our localization algorithm, we introduce mechanisms to preserve network formation during directed mobility in mobile sensor networks. Our simulations confirm that, in a number of realistic scenarios, our algorithm provides for a mobile sensor network that is stable over time irrespective of speed, while using only constant storage per neighbor.

SYSTEM REQUIREMENTS:
HARDWARE REQUIREMENTS:

•         System                 : Pentium IV 2.4 GHz.
•         Hard Disk            : 40 GB.
•         Floppy Drive       : 1.44 Mb.
•         Monitor                : 15 VGA Colour.
•         Mouse                  : Logitech.
•         Ram                      : 512 Mb.

SOFTWARE REQUIREMENTS:

•         Operating system                     :  Windows XP.
•         Coding Language           :  C#.NET
•         Data Base                       : SQL Server 2005
•         REPORT                       : EXCEL 2007


REFERENCE:
Harsha Chenji and Radu Stoleru, “Towards Accurate Mobile Sensor Network Localization in Noisy Environments”, IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. X, NO. X, JANUARY 2012.