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INTRODUCTION

1 Mobile phone tracking refers to the attaining of the current position of amobile phone, stationary ormoving. Localization may occur either viamultilaterationof radio signals between (several) radio towers of the

network and the phone, or simply via GPS. To locate the phone using multilateration of radio signals, it must

emit at least the roamingsignal to contact the next nearby antenna tower, but the process does not require an

active call.GSMis based on the signal strength to nearby antenna masts.[1]

Mobile positioning, which includes location based service that discloses the actual coordinates of a mobile

phone bearer, is a technology used bytelecommunicationcompanies toapproximatewhere amobile phone,

and thereby also its user (bearer), temporarily resides. The more properly applied term locatingrefers to the

purpose rather than a positioningprocess. Such service is offered as an option of the class oflocation-based

services

Mobile phone tracking

Mobile phone tracking refers to the attaining of the current position of amobile phone, stationary or moving.

Localization may occur either viamultilaterationof radio signals between (several) radio towers of the network

and the phone, or simply via GPS. To locate the phone using multilateration of radio signals, it must emit at

least the roamingsignal to contact the next nearby antenna tower, but the process does not require an active

call.GSMis based on the signal strength to nearby antenna masts.[1]

Mobile positioning, which includes location based service that discloses the actual coordinates of a mobile

phone bearer, is a technology used bytelecommunicationcompanies toapproximatewhere amobile phone,

and thereby also its user (bearer), temporarily resides. The more properly applied term locatingrefers to the

purpose rather than a positioningprocess. Such service is offered as an option of the class oflocation-based

services(LBS).[2]

Technology

The technology of locating is based on measuring power levels and antenna patterns and uses the concept

that a mobile phone always communicates wirelessly with one of the closestbase stations, so knowledge of the

location of the base station implies the cell phone is nearby.

Advanced systems determine the sector in which the mobile phone resides and roughly estimate also the

distance to the base station. Further approximation can be done byinterpolatingsignals between adjacent

antenna towers. Qualified services may achieve a precision of down to 50 meters inurban areaswhere mobile

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traffic and density of antenna towers (base stations) is sufficiently high.Ruraland desolate areas may see

miles between base stations and therefore determine locations less precisely.

GSM localization is the use ofmultilaterationto determine the location ofGSMmobile phones, or dedicated

trackers,[3][4]

usually with the intent to locate the user.[2]

Localization-Based Systems can be broadly divided into:

Network-based

Handset-based

SIM-based

Hybrid

1.Network-based

Network-based techniques utilize the service provider's network infrastructure to identify the location of the

handset. The advantage of network-based techniques (from mobile operator's point of view) is that they can be

implemented non-intrusively, without affecting the handsets.

The accuracy of network-based techniques varies, with cell identification as the least accurate

andtriangulationas moderately accurate, and newer "Forward Link" timing methods as the most accurate. The

accuracy of network-based techniques is both dependent on the concentration of base station cells, with urban

environments achieving the highest possible accuracy, and the implementation of the most current timing

methods.

One of the key challenges of network-based techniques is the requirement to work closely with the service

provider, as it entails the installation of hardware and software within the operator's infrastructure. Often, a

legislative framework, such asE911, would need to be in place to compel the cooperation of the service

provider as well as to safeguard the privacy of the information.

2.Handset-based

Handset-based technology requires the installation of client software on the handset to determine its location.

This technique determines the location of the handset by computing its location by cell identification, signal

strengths of the home and neighboring cells, which is continuously sent to the carrier. In addition, if the handset

is also equipped withGPSthen significantly more precise location information is then sent from the handset to

the carrier.

The key disadvantage of this technique (from mobile operator's point of view) is the necessity of installing

software on the handset. It requires the active cooperation of the mobile subscriber as well as software that

must be able to handle the different operating systems of the handsets. Typically,smartphones, such as one

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based onSymbian,Windows Mobile,Windows Phone,BlackBerry OS,iPhone, orAndroid, would be able to run

such software.

One proposed work-around is the installation of embedded hardware or software on the handset by the

manufacturers, e.g. E-OTD. This avenue has not made significant headway, due to the difficulty of convincing

different manufacturers to cooperate on a common mechanism and to address the cost issue. Another difficulty

would be to address the issue of foreign handsets that are roaming in the network.

3.SIM-based

Using the SIM inGSMandUMTShandsets, it is possible to obtain raw radio measurements from the

handset.[5][6]

The measurements that are available can include the servingCell ID, round trip time and signal

strength. The type of information obtained via the SIM can differ from what is available from the handset. For

example, it may not be possible to obtain any raw measurements from the handset directly, yet still obtain

measurements via the SIM.

4.Hybrid

Hybrid positioning systemsuse a combination of network-based and handset-based technologies for location

determination. One example would be some modes ofAssisted GPS, which can both useGPSand network

information to compute the location. Both types of data are thus used by the telephone to make the location

more accurate (i.e. A-GPS). Alternatively tracking with both systems can also occur by having the phone attain

his GPS-location directly from the satellites, and then having the information sent via the network to the person

that is trying to locate the telephone. Services allowing such cellphone tracking

areSouguide,Mologogo,instaMapper,Buddyway,VismoandGoogle Latitude.[7][8][9][10][11]

Operational purpose

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In order to route calls to a phone thecell towerslisten for a signal sent from the phone and negotiate which

tower is best able to communicate with the phone. As the phone changes location, the antenna towers monitor

the signal and the phone is roamedto an adjacent tower as appropriate.

By comparing the relative signal strength from multiple antenna towers a general location of a phone can be

roughly determined. Other means is the antenna pattern that supports angular determination and phase

discrimination.

Newer phones may also allow the tracking of the phone even when turned on and not active in a telephone

call-. This results from the roaming procedures that perform hand over of the phone from one base station to

another.[12]

Bearer interest

A phone's location can be uploaded to a common web site where one's "friends and family" can view one's last

reported position. Newer phones may have built-inGPS receiverswhich could be used in a similar fashion, but

with much higher accuracy.

Privacy

Locating or positioning touches upon delicateprivacyissues, since it enables someone to check where a

person is without the person's consent. Strict ethics and security measures are strongly recommended for

services that employ positioning, and the user must give an informed, explicitconsentto a service provider

before the service provider can compute positioning data from the user's mobile phone.

InEurope, where most countries have a constitutional guarantee on thesecrecy of correspondence, location

data obtained from mobile phone networks is usually given the same protection as the communication itself.

TheUnited Stateshowever has no explicit constitutional guarantee on theprivacy of telecommunications, so

use of location data is limited by law.

With tolling systems, as in Germany, the locating of vehicles is equally sensitive to the constitutional guarantee

on the secrecy of correspondence and thus any further use of tolling information beyond deducting the road fee

is prohibited. Even obviously criminal intent may not be inferred by such means, although such a use is

technically possible.

Officially, theauthorities(like thepolice) can obtain permission to position phones inemergencycases where

people (including criminals) are missing. The U.S. Justice Department has argued that current laws allow them

to track suspects without having probable cause to suspect a law is being violated.[13]

In some instances law

enforcement may even access a mobile phone's internal microphone to eavesdrop on local conversations while

the phone is switched off.[14]

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TheElectronic Frontier Foundationis tracking some cases, includingUSA v. Pen Register, regarding

government tracking of individuals.[15]

Some "Free" tracking services allow the cellular telephone number being tracked to be added totelemarketers'

lists.

Chinahas proposed using this technology to track commuting patterns ofBeijingcity residents.[16]

Real-time locating system-The principle of mobiletracking

Real-time locating systems (RTLS) are a type oflocal positioning systemthat allow to track and identify the

location of objects in real time. Using simple, inexpensive badges or tags attached to the objects, readers

receive wireless signals from these tags to determine their locations.[1]

RTLS typically refers to systems that

provide passive or active (automatic) collection of location information.

Location information usually does not include speed, direction, or spatial orientation. These additional

measurements would be part of a navigation, maneuvering or positioning system.

Origin

The term RTLS was created (circa 1998) to describe an emerging technology that not only provided the

Automatic Identification capabilities of activeRFIDtags, but added the ability to see the physical location of the

tagged asset on a computer screen. Although this capability had been utilized previously by military and

government agencies, the technology had been too expensive for commercial purposes.

By the early 1990s, commercialization began at two healthcare facilities in the United States (Foote

HospitalinJackson, MIandBroward Children's HospitalinPompano Beach, FL). These early adopters are

attributed to real-time locating industry innovator Precision Tracking (Versus Technology, Inc.) and were based

on the transmission and decoding of infrared light signals from actively transmitting tags.

System designs

RTLS excludes passiveRFIDindexing (radio frequency transponder indexers) andCellnetbase station

segment locators (location-based services) from the scope of theISO/IECapproach toRTLS standardizationas

well as allbeaconsystems, thatpingwithout request. RTLS systems apply typically in confined areas, where

the required reference points would be equipped with wireless anchor nodes.

Operation

For RTLS to function, the location of tagged items must be determined either by a central processor or by an

embedded mobile computing facility. Locating is generally accomplished in one of the following ways

http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-13http://en.wikipedia.org/wiki/Electronic_Frontier_Foundationhttp://en.wikipedia.org/wiki/Electronic_Frontier_Foundationhttp://en.wikipedia.org/wiki/Electronic_Frontier_Foundationhttp://www.eff.org/legal/cases/USA_v_PenRegister/http://www.eff.org/legal/cases/USA_v_PenRegister/http://www.eff.org/legal/cases/USA_v_PenRegister/http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-14http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-14http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-14http://en.wikipedia.org/wiki/Telemarketerhttp://en.wikipedia.org/wiki/Telemarketerhttp://en.wikipedia.org/wiki/Telemarketerhttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/Beijinghttp://en.wikipedia.org/wiki/Beijinghttp://en.wikipedia.org/wiki/Beijinghttp://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-15http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-15http://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-15http://en.wikipedia.org/wiki/Local_positioning_systemhttp://en.wikipedia.org/wiki/Local_positioning_systemhttp://en.wikipedia.org/wiki/Local_positioning_systemhttp://en.wikipedia.org/wiki/Real-time_locating#cite_note-0http://en.wikipedia.org/wiki/Real-time_locating#cite_note-0http://en.wikipedia.org/wiki/Real-time_locating#cite_note-0http://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/Jackson,_MIhttp://en.wikipedia.org/wiki/Jackson,_MIhttp://en.wikipedia.org/wiki/Jackson,_MIhttp://en.wikipedia.org/wiki/Broward_Healthhttp://en.wikipedia.org/wiki/Broward_Healthhttp://en.wikipedia.org/wiki/Broward_Healthhttp://en.wikipedia.org/wiki/Pompano_Beach,_FLhttp://en.wikipedia.org/wiki/Pompano_Beach,_FLhttp://en.wikipedia.org/wiki/Pompano_Beach,_FLhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/Cellnethttp://en.wikipedia.org/wiki/Cellnethttp://en.wikipedia.org/wiki/Cellnethttp://en.wikipedia.org/wiki/Location-based_servicehttp://en.wikipedia.org/wiki/Location-based_servicehttp://en.wikipedia.org/wiki/Location-based_servicehttp://en.wikipedia.org/wiki/ISOhttp://en.wikipedia.org/wiki/ISOhttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/Real-time_locating_standardshttp://en.wikipedia.org/wiki/Real-time_locating_standardshttp://en.wikipedia.org/wiki/Real-time_locating_standardshttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Pinghttp://en.wikipedia.org/wiki/Pinghttp://en.wikipedia.org/wiki/Pinghttp://en.wikipedia.org/wiki/Pinghttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Real-time_locating_standardshttp://en.wikipedia.org/wiki/International_Electrotechnical_Commissionhttp://en.wikipedia.org/wiki/ISOhttp://en.wikipedia.org/wiki/Location-based_servicehttp://en.wikipedia.org/wiki/Cellnethttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/Pompano_Beach,_FLhttp://en.wikipedia.org/wiki/Broward_Healthhttp://en.wikipedia.org/wiki/Jackson,_MIhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/Foote_Hospitalhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/Real-time_locating#cite_note-0http://en.wikipedia.org/wiki/Local_positioning_systemhttp://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-15http://en.wikipedia.org/wiki/Beijinghttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/Telemarketerhttp://en.wikipedia.org/wiki/Mobile_phone_tracking#cite_note-14http://www.eff.org/legal/cases/USA_v_PenRegister/http://en.wikipedia.org/wiki/Electronic_Frontier_Foundation

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1. ID signals from nodes are identifiable to a single reader in a sensory network thus indicating the

coincidence of reader and nodes.

2. ID signals from nodes are picked up by a multiplicity of readers in a sensory network and a position is

estimated using one or more locating algorithms

3. Location signals from signposts with identifiers are transmitted to the moving nodes and are then

relayed, usually via a second wireless channel, to a location processor.

4. Mobile nodes communicate with each other and perform metering distances.

Examples one (1) and three (3) have much of the same characteristics. They typically require that a node be

assigned at a time to a single reader/signpost. Separation from overlapping readers/signposts is roughly

provided by RSSI or Physical Space Division (walls/floors/ceilings). Readers/signposts are often associated

with highly stable location boundaries (i.e. a room or room division). In these examples, locations are listed as

"Current Location" or "Last Known Location."

Example two (2) requires that distances between nodes in the sensory network be determined in order to

precisely locate a node. In this instance, the determination of the location is called Localization. The location is

calculated throughTrilaterationorMultilaterationfrom the determined distance between the nodes or

throughTriangulationfrom the determined angles between nodes. The determination of distances is

calledRanging.

Application

RTLS serves in operational areas for logistics and other services,as for example stock grounds or storehouses,

and for servicing areas in clinics and industrial plants. Tasks done by a RTLS include:

to combine identity and location of any type of items or objects

to combine identity of items with location of lifter placing the items

to ensure permanent availability of proper information about temporary placement

to support notification of placing of items

to prove proper manning of operational areas

to prove consequent evacuation of endangered areas

to make marshalling staff dispensable

Standards

ISO/IEC

The basic issues of RTLS are standardized by theInternational Organization for Standardizationand the

International Electrotechnical Commission, under the ISO/IEC 24730 series. In this series of standards, the

http://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Ranginghttp://en.wikipedia.org/wiki/Ranginghttp://en.wikipedia.org/wiki/Ranginghttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/Ranginghttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Trilateration

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basic standard ISO/IEC 24730-1 identifies the terms describing a form of RTLS used by a set of vendors, but

does not encompass the full scope of RTLS technology.

Currently several standards are published or under discussion:

ISO/IEC FDIS 19762-5 Information technology AIDC techniques Harmonized vocabulary, Part 5

Locating systems

ISO/IEC 24730-1:2006 Information technologyreal-time locatingsystems (RTLS) Part 1: Application

program interface (published).

ISO/IEC 24730-2:2006 Information technologyreal-time locatingsystems (RTLS) Part 2: 2,4 GHz Air

interface protocol (published, WhereNet/Zebra approach).

ISO/IEC WD 24730-5 Information technologyreal-time locatingsystems (RTLS) Part 5: (drafted ISO/IEC

standard out for balloting in 2008, Nanotron approach).

The other proposals ISO/IEC 24730-3 and ISO/IEC 24730-4 had never left the stage of intention. For copies of

these documents see references.

These standards do not stipulate any special method of computing locations, nor the method of measuring

locations. This may be defined in specifications fortriangulationor any hybrid approaches to trigonometric

computing for planar or spherical models of a terrestrial area.

Ranging

Ranging, as a special term for measuring distance, is the prerequisite for locating. Measuring a bearing angle,

i.e. angulatingis the other alternative.

Determining the distance may be either a non cooperative scanning process, as withRADARorLIDAR, or a

cooperative direct distance measuring process, as with RTLS. A scanned beam may form an overall image as

a model of the whole scene. In all other cases the image of the scene is rather selective.

The following step is extracting the distance information from the scanned image. Direct distance measurement

with a single beam targets only the object to be measured, for example, with a laser. This method requires

additional information about the direction of the beam. The remaining method is omni-directional transmission

with a signal containing an address code. Only the addressed object responds to the request. The time

required for the signal to reach the object can be used to calculate the distance. After completing the distance

measurement, the location may be computed.

There are two different principles when measuring travel time of radio waves:

Trilaterationderives the travel time of a radio signal from a metering unit, and measures and computes the

distance with the relation of light speed in vacuum, the (Time of arrivalconcept).

http://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/LIDARhttp://en.wikipedia.org/wiki/LIDARhttp://en.wikipedia.org/wiki/LIDARhttp://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Trilaterationhttp://en.wikipedia.org/wiki/LIDARhttp://en.wikipedia.org/wiki/RADARhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locatinghttp://en.wikipedia.org/wiki/Real-time_locating

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Triangulationderives the travel time of a pair of synchronous radio signals from a metering unit with two

transmitters, and measures and computes the difference of distance with the relation of light speed in

vacuum as an angle versus the baseline of the two transmitters (TDOA time difference of arrivalconcept).

All the terms named here just apply to measurement concepts. All information about location is for services

applied to mobile or portable or otherwise transportable objects. Location information may be relevant for

managing interaction of persons with services as well.

Angle of arrival(AoA)

Line-of-sight(LoS)

Time of arrival(ToA)

Multilateration(Time difference of arrival) (TDoA)

Time-of-flight(ToF)

Two-way ranging (TWR) according toNanotrons patents

Symmetrical Double Sided Two Way Ranging(SDS-TWR)

Near-field electromagnetic ranging(NFER)

Privacy concerns

RTLS may be seen a threat to privacy, if applied to persons, either directly or parasitically. The requirement

therefore is to describe the purpose and the conditions of operation to those affected and to advertise for

expressed agreement. Recent adjustment of jurisdiction leads to more careful assessment of needs and

options. The newly declared human right of informational self-determinationde:Informationelle

Selbstbestimmung, i.e. to prevent one's identity and personal data from disclosure to others, covers disclosure

of locality as well. Base of discussion is very similar to disclosure of personal data for passing immigration at

US airports: Balancing threat and burden[4].

Locating concepts

A lot of systems concepts sails under the label of real-time locating systems. However the qualification of these

approaches is very different and offers a wide variation of cost-to-benefit ratio.

1.Locating at choke points

There is class of most simple locating which applies no physical measurement at all, but just communicates at

coincidence of transceiver and transponder as long as communication may happen. Then locating collapses to

simple application ofRFIDtechnologies according to the equivalent standard.[20]

This is the only option to apply

passive RFID tags for locating. Then the reach of the RFID reader determines the choke point. Hence accuracy

is defined by the sphere spanned with the reach of the reader. The concept does not serve for discrimination of

http://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/Triangulationhttp://en.wikipedia.org/wiki/TDOAhttp://en.wikipedia.org/wiki/TDOAhttp://en.wikipedia.org/wiki/TDOAhttp://en.wikipedia.org/wiki/Angle_of_arrivalhttp://en.wikipedia.org/wiki/Angle_of_arrivalhttp://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Time-of-flighthttp://en.wikipedia.org/wiki/Time-of-flighthttp://en.wikipedia.org/w/index.php?title=Nanotron&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Nanotron&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Nanotron&action=edit&redlink=1http://en.wikipedia.org/wiki/Symmetrical_Double_Sided_%E2%80%93_Two_Way_Ranginghttp://en.wikipedia.org/wiki/Symmetrical_Double_Sided_%E2%80%93_Two_Way_Ranginghttp://en.wikipedia.org/wiki/Symmetrical_Double_Sided_%E2%80%93_Two_Way_Ranginghttp://en.wikipedia.org/wiki/Symmetrical_Double_Sided_%E2%80%93_Two_Way_Ranginghttp://en.wikipedia.org/wiki/Near-field_electromagnetic_ranginghttp://en.wikipedia.org/wiki/Near-field_electromagnetic_ranginghttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://www.hasbrouck.org/articles/PNR.htmlhttp://www.hasbrouck.org/articles/PNR.htmlhttp://www.hasbrouck.org/articles/PNR.htmlhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/RFIDhttp://en.wikipedia.org/wiki/Real-time_locating#cite_note-19http://en.wikipedia.org/wiki/Real-time_locating#cite_note-19http://en.wikipedia.org/wiki/Real-time_locating#cite_note-19http://en.wikipedia.org/wiki/Real-time_locating#cite_note-19http://en.wikipedia.org/wiki/RFIDhttp://www.hasbrouck.org/articles/PNR.htmlhttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://de.wikipedia.org/wiki/Informationelle_Selbstbestimmunghttp://en.wikipedia.org/wiki/Near-field_electromagnetic_ranginghttp://en.wikipedia.org/wiki/Symmetrical_Double_Sided_%E2%80%93_Two_Way_Ranginghttp://en.wikipedia.org/w/index.php?title=Nanotron&action=edit&redlink=1http://en.wikipedia.org/wiki/Time-of-flighthttp://en.wikipedia.org/wiki/Multilaterationhttp://en.wikipedia.org/wiki/Time_of_arrivalhttp://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Angle_of_arrivalhttp://en.wikipedia.org/wiki/TDOAhttp://en.wikipedia.org/wiki/Triangulation

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direction on passage, unless the reader is enhanced with a two distant antenna inputs to determine a sequence

of activation and deactivation of the pair of antennae.

2.Locating in relative coordinates

Many references describe locating at relative coordinates. Such coordinates may be radial distances comparedwith reference to known locations and no angular directions. There is no exact metrics required, unless the

relation to the reference points is intelligible. This is a valuable support for many operational needs, whereas

the precision of the term RTLS is widely diluted to arbitrary interpretation. Such solutions may be referred

asfuzzy locating.

3.Locating in absolute coordinates

The high precision of satellite navigation systems led to some snugness in setting the requirements for locating

of objects. generally the determining of absolute coordinates is the most challenging approach. Such solutions

may be referred ascrisp locating. The difference to the qualities of relative coordinates may be easily

understood with indoor sensor operations, where satellites are not commonly available for referring to global

coordinates and when always a multiplicity of errors applies. The most challenging problem with modern

modulation concepts still is multi-path propagation, which causes ambiguous results of erratic measurement.

A sound escape from electromagnetics and surface effects is found with ultra short pulse communications, as

withUWBindoor approaches. However, many such concepts often do not serve results for the paid price when

the targets move. This may be assessed by the vast number of publications and the very small references on

installed solutions

4.Locating in contiguity

A newer approach for locating defines a location just as the contiguous ambience of the person looking for

something to be located. That is very similar to choke point locating. However, the accuracy may be much

better tuned, as the reach is not influenced by the steady illumination of the tag with the reader, but just by the

tuned transmission power level of an active RFID tag as an itermittentbeacon.

This is the easy option to apply graded active RFID tags for economised locating. Then the reach of the RFID

receiver determines the base point. Hence operational suitability is defined by the algorithm for varying the

minimum reach of transmission of the beacon. Solutions are available as very simpleelectronic leashesor in

more complex designs. A very common application is with electronicwireless locksolutions. More advanced

applications combine the tag operation with autonomously operatingsoftware agents, e.g. insmartphonesfor

monitoring manually controlled systems and services.[21]

Erratic effects in locating systems

http://en.wikipedia.org/wiki/Fuzzy_locatinghttp://en.wikipedia.org/wiki/Fuzzy_locatinghttp://en.wikipedia.org/wiki/Fuzzy_locatinghttp://en.wikipedia.org/wiki/Crisp_locatinghttp://en.wikipedia.org/wiki/Crisp_locatinghttp://en.wikipedia.org/wiki/Crisp_locatinghttp://en.wikipedia.org/wiki/UWBhttp://en.wikipedia.org/wiki/UWBhttp://en.wikipedia.org/wiki/UWBhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/Electronic_leashhttp://en.wikipedia.org/wiki/Electronic_leashhttp://en.wikipedia.org/wiki/Electronic_leashhttp://en.wikipedia.org/wiki/Wireless_lockhttp://en.wikipedia.org/wiki/Wireless_lockhttp://en.wikipedia.org/wiki/Wireless_lockhttp://en.wikipedia.org/wiki/Software_agenthttp://en.wikipedia.org/wiki/Software_agenthttp://en.wikipedia.org/wiki/Software_agenthttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Real-time_locating#cite_note-20http://en.wikipedia.org/wiki/Real-time_locating#cite_note-20http://en.wikipedia.org/wiki/Real-time_locating#cite_note-20http://en.wikipedia.org/wiki/Real-time_locating#cite_note-20http://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Software_agenthttp://en.wikipedia.org/wiki/Wireless_lockhttp://en.wikipedia.org/wiki/Electronic_leashhttp://en.wikipedia.org/wiki/Beaconhttp://en.wikipedia.org/wiki/UWBhttp://en.wikipedia.org/wiki/Crisp_locatinghttp://en.wikipedia.org/wiki/Fuzzy_locating

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Real-time locating is affected by a variety of errors. The major reasons are physical and may not be reduced by

improving the technical equipment. The only escape is mathematical intelligence to improve.

1.None or no direct response

Many RTLS systems have a very mundane requirement: they require direct and clear wireless visibility. Forthose systems, where there is no visibility on the path from mobile tags to resident nodes there will be no result

or a non valid result from locating engine. This applies to satellite locating as well as other RTLS systems such

as angle of arrival and time of arrival. Fingerprinting is a way to overcome the visibility issue: If the locations in

the tracking area contain distinct measurement fingerprints, line of sight is not necessarily needed. For

example, if each location contains a unique combination of signal strength readings from transmitters, the

location system will function properly. This is true, for example, with some Wi-Fi based RTLS solutions.

However, having distinct signal strength fingerprints in each location typically requires a fairly high saturation of

transmitters.

2.False location

The measured location may appear entirely faulty. This is a generally result of simple operational models to

compensate for the plurality of error sources. It proves impossible to serve proper location after ignoring the

errors.

3.Locating backlog

Real timeis no registered branding and has no inherent quality. A variety of offers sails under this term. As

motion causes location changes, inevitably the latency time to compute a new location may be dominant with

regard to motion. Either an RTLS system that requires waiting for new results is not worth the money or the

operational concept that asks for faster location updates does not comply with the chosen systems approach.

4.Temporary location error

Location will never be reported exactly, as the term real-timeand the term precisiondirectly contradict in

aspects of measurement theory as well as the term precisionand the term costcontradict in aspects of

economy. That is no exclusion of precision, but the limitations with higher speed are inevitable.

5.Steady location error

Recognizing a reported location steadily apart from physical presence generally indicates the problem ofinsufficient over-determination and missing of visibility along at least one link from resident anchors to mobile

transponders. Such effect is caused also by insufficient concepts to compensate for calibration needs.

6.Location jitter

Noise from various sources has an erratic influence on stability of results. The aim to provide a steady

appearance increases the latency contradicting to real time requirements.

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7.Location jump

As objects containing mass have limitations to jump, such effects are mostly beyond physical reality. Jumps of

reported location not visible with the object itself generally indicate improper modeling with the location engine.

Such effect is caused by changing dominance of various secondary responses.

8.Location creep

Location of residing objects gets reported moving, as soon as the measures taken are biased by secondary

path reflections with increasing weight over time. Such effect is caused by simple averaging and the effect

indicates insufficient discrimination of first echoes.