Position information of individual nodes is useful in implementing functions such as routing and querying in ad-hoc networks. Deriving position information by using the capability of the nodes to measure time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA) and signal strength have been used to localize nodes relative to a frame of reference. The nodes in an ad-hoc network can have multiple capabilities and exploiting one or more of the capabilities can improve the quality of positioning. In this paper, we show how AOA capability of the nodes can be used to derive position information. We propose a method for all nodes to determine their orientation and position in an ad-hoc network where only a fraction of the nodes have positioning capabilities, under the assumption that each node has the AOA capability.

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Ad hoc positioning system (APS) using AOA

The Global Positioning System (GPS) is a satellite-based navigation and time transfer system developed by the U.S. Department of Defense. It serves marine, airborne, and terrestrial users, both military and civilian. Specifically, GPS includes the Standard Positioning Service (SPS) which provides civilian users with 100 meter accuracy, and it serves military users with the Precise Positioning Service (PPS) which provides 20-m accuracy. Both of these services are available worldwide with no requirement for a local reference station. In contrast, differential operation of GPS provides 2- to 10-m accuracy to users within 1000 km of a fixed GPS reference receiver. Finally, carrier phase comparisons can be used to provide centimeter accuracy to users within 10 km and potentially within 100 km of a reference receiver. This advanced tutorial will describe the GPS signals, the various measurements made by the GPS receivers, and estimate the achievable accuracies. It will not dwell on those aspects of GPS which are well known to those skilled in the radio communications art, such as spread-spectrum or code division multiple access. Rather, it will focus on topics which are more unique to radio navigation or GPS. These include code-carrier divergence, codeless tracking, carrier aiding, and narrow correlator spacing.

Global Positioning System: Signals, Measurements, and Performance

We present a new approach to remote sensing of water vapor based on the global positioning system (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-varying zenith wet delay (ZWD) which is retrieved by stochastic filtering of the GPS data. Given surface temperature and pressure readings at the GPS receiver, the retrieved ZWD can be transformed with very little additional uncertainty into an estimate of the integrated water vapor (IWV) overlying that receiver. Networks of continuously operating GPS receivers are being constructed by geodesists, geophysicists, government and military agencies, and others in order to implement a wide range of positioning capabilities. These emerging GPS networks offer the possibility of observing the horizontal distribution of IWV or, equivalently, precipitable water with unprecedented coverage and a temporal resolution of the order of 10 min. These measurements could be utilized in operational weather forecasting and in fundamental research into atmospheric storm systems, the hydrologic cycle, atmospheric chemistry, and global climate change. Specially designed, dense GPS networks could be used to sense the vertical distribution of water vapor in their immediate vicinity. Data from ground-based GPS networks could be analyzed in concert with observations of GPS satellite occultations by GPS receivers in low Earth orbit to characterize the atmosphere at planetary scale.

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GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System

Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute location of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding location without the aid of GPS in each node of an ad hoc network is important in cases where GPS is either not accessible, or not practical to use due to power, form factor or line of sight conditions. Location would also enable routing in sufficiently isotropic large networks, without the use of large routing tables. We are proposing APS - a distributed, hop by hop positioning algorithm, that works as an extension of both distance vector routing and GPS positioning in order to provide approximate location for all nodes in a network where only a limited fraction of nodes have self location capability.

/pdf/ad-hoc-positioning-system-aps-3roowtu3q3.pdf

Ad hoc positioning system (APS)

Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute position of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding position without the aid of GPS in each node of an ad hoc network is important in cases where GPS is either not accessible, or not practical to use due to power, form factor or line of sight conditions. Position would also enable routing in sufficiently isotropic large networks, without the use of large routing tables. We are proposing APS --- a localized, distributed, hop by hop positioning algorithm, that works as an extension of both distance vector routing and GPS positioning in order to provide approximate position for all nodes in a network where only a limited fraction of nodes have self positioning capability.

/pdf/dv-based-positioning-in-ad-hoc-networks-12d026gqcv.pdf

DV Based Positioning in Ad Hoc Networks

This paper analyzes the theoretical performance of an idealized Assisted GPS (A-GPS) receiver in inclement urban environments. The results suggest that if reliability, accuracy, and rapid acquisition time are important for wireless applications that are used indoors, an augmentation technology is necessary. The rest of the paper is devoted to exploring a positioning technology that uses embedded synchronization signals in TV broadcasts. The technique discussed herein could be used to position personal digital assistants (PDAs), laptops, cellular phones, two-way radios, and asset-tracking devices. Since the technique makes use of signals that are part of the TV standard, no changes to broadcast stations are required. The TV synchronization signals typically have a power advantage over GPS of more than 40 dB. In addition, the effects of multipath are substantially mitigated since the signals have a bandwidth of roughly 6 MHz, and superior lateral geometry for triangulation relative to stand-alone GPS.

Augmenting GPS with Television Signals for Reliable Indoor Positioning

Apparatus to determine the position of a user terminal, the apparatus having corresponding methods and computer-readable media, comprise: a receiver to receive at the user terminal an American Television Standards Committee Mobile/Handheld (ATSC-M/H) broadcast signal from a ATSC-M/H transmitter; and a pseudorange module to determine a pseudorange between the receiver and the ATSC-M/H transmitter based on the ATSC-M/H) broadcast signal; wherein the position module determines the position of the user terminal based on the pseudorange and a location of the ATSC-M/H transmitter.

Position Determination Using ATSC-M/H Signals

PROBLEM TO BE SOLVED: To provide a computer programming product for determining the positions of user devices, a system, and a method therefor. SOLUTION: A plurality of digital television (DTV) broadcasting signals from a plurality of DTV transmitters are received in user devices, the pseudo distances between user devices and respective DTV transmitters are determined based on the DTV broadcasting signals, and then the positions of the user devices are determined based on the pseudo distances and the positions of respective DTV transmitters. Examples of DTV signals include Advanced Television Systems Committee (ATSC) signals, European Telecommunications Standards Institute Digital Video Broadcasting Terrestrial Wave (DVB-T) signals, and Japan Terrestrial Digital Television Broadcasting System (ISDV-T) signals. COPYRIGHT: (C)2004,JPO

Position verification determination that allows easy numeralization, contributes to total cost reductions of colorants containing those for remained color and specific color, and uses broadcasting digital television signals

Apparatus having corresponding computer programs comprise: a code generator adapted to generate a transmitter identification block, wherein the transmitter identification block comprises 32 rows and 82 columns, wherein the first 66 symbols in each of the rows comprises a cyclically-extended 63-chip pseudonoise code that is selectively polarity-inverted according to a respective phase of a 32-chip Walsh code, and wherein each of the last 16 columns comprises a parity-extended 31-chip Gold code that is selectively polarity-inverted according to a respective phase of a 16-chip Walsh code; and a code inserter adapted to insert each of the rows into the reserved block of a respective one of 32 consecutive field synchronization segments in an Advanced Television Systems Committee (ATSC) television signal prior to transmission of the ATSC television signal.

ATSC transmitter identifier signaling

A method, apparatus, and computer-readable media for determining the position of a user terminal comprises receiving at the user terminal (102) a broadcast television signal from a television signal transmitter; determining a first pseudo-range between the user terminal and the television signal transmitter based on a known component of the broadcast television signal; receiving at the user terminal a global positioning signal from a global positioning satellite; determining a second pseudo-range between the user terminal and the global positioning satellite based on the global positioning signal; and determining a position of the user terminal based on the first and second pseudo-ranges, a location of the television signal transmitter, and a location of the global positioning satellite.

James J. Spilker

Papers

Augmenting GPS with Television Signals for Reliable Indoor Positioning

Position Determination Using ATSC-M/H Signals

Position verification determination that allows easy numeralization, contributes to total cost reductions of colorants containing those for remained color and specific color, and uses broadcasting digital television signals

ATSC transmitter identifier signaling

Position location using gps augmented by tv