Identification of the location of nodes distributed in ad hoc networks

Abstract

A location of node i in a network having a plurality of nodes is identified by intersecting regions that are guaranteed to contain the node i with respect the other nodes that are neighbors of the node i and iteratively minimizing the size of the intersection region containing the node i.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to locating nodes in networks such as ad hoc networks.BACKGROUND OF THE INVENTION[0002]Typically, the nodes of an ad hoc network are randomly and arbitrarily deployed in such a manner that their locations are not necessarily known a priori. For example, wireless sensors are often deployed in ad hoc networks and are used for sensing, detection, and tracking. Such networks are being applied in military, ecological, environmental, and domestic systems for monitoring and / or control. Wireless sensor networks are also being used to automate buildings, universities, factories, etc. Because of the ad hoc nature of these networks, few assumptions can be made about their topologies.[0003]Further, in some cases, the nodes of a network can change locations with varying or constant frequency. A network comprised of such mobile nodes is typically referred to as a mobile network.[0004]Most location estimation systems locate the no...

AI Technical Summary

Benefits of technology

[0012]According to one aspect of the present invention, a method of identifying a location of a node i in a network having a plurality of nodes comprises the following: receiving a location of a region that is guaranteed to contain the node i, wherein the determining of a location of a region is based on range information obtained with respect to other nodes in a neighborhood of the node i; determining a region of residence of the node i based on the region that is guaranteed to contain the node i, wherein the region residence has a size; and, iteratively minimizing the size of the region of residence of the node i.

[0013]According to another aspect of the present invention, a computer readable storage medium has program code stored thereon which, when executed, identifies a location of node i in a wireless network having a plurality of nodes by performing the following functions: a) receiving a location of a first region from a node j, wherein the first region is guaranteed to contain the node i, wherein the first region has a size, wherein the size of the first region is dependent upon a range between the nodes i and j, and wherein the node j is within a transmission range of the node i; b) receiving a location of a second region from a node k, wherein the second region is guaranteed to contain the node i, wherein the second region has a size, wherein the size of the second region is dependent upon a range between the nodes i and k, and wherein the node k is within a transmission range of the node i; c) receiving a location of a third region from a node l, wherein the third region is guaranteed to contain the node i, wherein the third region has a size, wherein the size of the third region is dependent upon a range between the nodes i and l, and wherein the node l is within a transmission range the node i; d) determining a minimum region of residence of the node i from an intersection of the first, second, and third regions; and, e) iteratively reducing the size of the minimum region of residence of the node i.

Problems solved by technology

The corruption of LOS signals by NLOS signals and also by Gaussian measurement noise are the major sources of error in all location estimation systems.

Unfortunately, GPS does not scale well in dense urban areas or in indoor locations.

While reasonably accurate radio propagation models exist for outdoor conditions, there are unfortunately no such unanimously accepted models for indoor environments.

However, in the absence of a suitable model for predicting the location of a mobile terminal, it is possible that the node may be far away from its estimated location.

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