Indoor geolocation is an emerging technology that has applications in commercial, public safety, and military domains. It uses various techniques like RSS, AOA, TOA, and TDOA to locate tags or mobile devices within buildings. Key challenges include multipath effects from the indoor environment and lack of line of sight between devices, which reduce location accuracy. Existing short-range technologies like RFID have limited range, while mid-range options have reliability issues. The 3D-iD system presented a potential solution using an indoor antenna infrastructure and cell controllers to determine tag locations through triangulation of signal distances to multiple antennas.

1. INDOOR GEOLOCATION
PRESENTED BY
D.LAKSHMI SOUJANYA
09951A0418
ECE IV A

2. Introduction
 Indoor geolocation is an important and novel emerging technology
for commercial, public safety and military applications.
 In commercial applications for residential and nursing homes there is
an increasing need for indoor geolocation systems to track people
with special needs, the elderly, and children who are away from
visual supervision, to locate in-demand portable equipment in
hospitals, and to find specific items in warehouses.
 In public safety and military applications, indoor geolocation systems
are needed to track inmates in prisons, and navigating policeman,
firefighters and soldiers to complete their missions inside buildings
 These incentives have initiated interest in modeling the radio channel
for indoor geolocation, development of new technologies, and
emergence of first generation indoor geolocation products

3. Global Positioning System (Gps) And E-
911 Services
 GPS is a worldwide space based radio navigation system that works
with the help of a constellation of 24 satellites and their base stations.
 It employs signal timing to determine position of a mobile station,
which acts, as the receiver and orbiting satellites are transmitters
 An Enhanced 9-1-1 system provides a three-digit dialing, no-coin
requirement from pay telephones and intelligent routing to the Public
Safety Answering Point (PSAP) that handles the area where the
phone is located and is able to display the caller's address and
telephone number at the PSAP for the dispatcher's reference.
 In general, 9-1-1 is an emergency number for any police, fire or
medical incident

4. System Architecture
 The architecture of indoor geolocation systems also can be roughly
grouped into two main categories: handset based architecture and
network-based architecture
 In network-based architecture the geolocation base stations extract
location metrics of the mobile station and relay this information to a
central control station.
 The control station, calculating the metrics it receives, keeps track of
the mobile station.
 In handset-based architecture, the mobile station estimates self-
position by measuring received radio signals from multiple fixed
base stations

5. Wireless Geolocation Systems

6.  The basic function of a wireless geolocation system is to gather a
particular information about the position of a mobile station (MS)
and process that information to form a location estimate
 The main elements of the system are a number of location sensing
devices that measure metrics related to the relative position of a
mobile station with respect to a known fixed station, a positioning
algorithm that processes metrics reported by location sensing
terminals to estimate the location coordinates of MS, and a display
system that illustrates the location of MS to users.
 The location metrics may indicate the approximate arrival direction
of the signal or the distance between the MS and FS

7. Geolocation Process
 Geolocation systems attempt to locate an MS by measuring the
signals traveling between the MS and a set of fixed stations (FS's).
 The signal measurements are first used to determine the length or
direction of the path, and then the MS position is derived from
known geometric relationships.
 It is important to note that line-of-sight (LOS) propagation is
necessary for accurate location estimates.
 The indoor radio propagation channel is characterized as site-
specific, severe multipath, and low probability for availability of a
line of sight (LOS) signal propagation path between transmitter and
receiver.
 The most important impact on location accuracy is due to the
range/direction estimation error.
 The two major sources of errors that come under this category, in the
measurement of location metrics in indoor environments are
multipath fading and no LOS (NLOS) conditions due to shadow
fading

8. RSS Geolocation
 In systems using RSS geolocation technique, nearness of an MS to
fixed detection devices is used to determine its position.
 RSS techniques estimate the location of an MS by measuring the
power transmitted by it.
 Simple geometric relationships are then used to form the location
estimate, based on the RSS measurements and the known positions
of the BS's.
 Once the power transmitted by a mobile terminal is known,
measuring received signal strength at receiver will provide the
distance between the transmitter and the receiver using a known
mathematical model for radio signal path loss with distances.
 The measured distance will determine a circle, centered at the
receiver, on which the mobile transmitter must lie.
 Three RSS measurements will provide a position fix for the mobile

9. AOA Geolocation
 The AOA geolocation method uses simple triangulation to locate the
transmitter.
 The receiver measures the direction of received signals (i.e. angle of
arrival) from the target transmitter using directional antennas or
antenna arrays.
 Simple geometric relationships arc then used to form the location
estimate, based on the AOA measurements and the known positions
of the BS's.
 With the AOA method, a position fix requires a minimum of two
BS's in a 2-D plane.
 Multipath propagation, in the form of scattering near and around the
MS and BS, will affect the measured AOA.
 As a result, more that two receivers are normally needed to improve
the location accuracy

10. TOA/TDOA Geolocation
 Time of Arrival
 Time Difference of Arrival
 Time-Based Location

11. Positioning Algorithms
 TRADITIONAL TECHNIQUES
– In the indoor radio channel, it is difficult to accurately measure
AOA and RSS so that most of the independent indoor
positioning systems mainly use TOA based techniques.
– With reliable TOA based measurements, simple geometrical
triangulation methods can be used to find the location of Ms.
– Due to estimation errors of distances at BS receivers caused by
inaccurate TOA measurements, the geometrical triangulation
technique can only provide a region of uncertainly instead of a
single position fix, for estimated location of the MS.
– To obtain an estimate of the location coordinates in the presence
of measurement errors of location metrics, a variety of direct and
iterative statistical positioning algorithms have been developed to
solve the problem by formulating it into a set of nonlinear
equations

12.  PATTERN RECOGNITION TECHNIQUES
– For indoor geolocation applications, the service area is restricted to
inside and close vicinity of a building, and nowadays the building floor
plan is normally accessible as an electronic document.
– The availability of electronic building floor plans is one of the features
of indoor applications that can be exploited in positioning algorithms
– Another unique feature of indoor application is that the size of coverage
area is much smaller than outdoor applications.
– This makes it possible to conduct comprehensive planning of placement
of sensors
– Operation of Geolocation Technique is based on 2 phases:
– - Off-Line phase (Phase of data collection) or
Learning phase
– - Real-Time phase (Phase of user's position location)

13. Goals Of An Indoor Positioning System
 So-called tags, physical devices associated with the people and assets being
tracked, which should be as small and light as possible for the widest
applicability.
 Tags that are inexpensive, for broad appeal and applicability, and therefore
far simpler in design than GPS receivers.
 An infrastructure that tracks thousands of tags, whereas in GPS, a mobile
device must determine its own location in reference to an infrastructure.
 Accuracy of 10 meters for most indoor applications, though some require 2-
meter accuracy or better.
 Counteraction of indoor multipath effects, a challenge when combined with
the higher accuracy requirement.

14. Existing Short-range Technologies
 Since the invention of the microprocessor a variety of short-range
radio-based technologies have been employed to track items indoors.
 They identify objects with a sensor having a range of a few
centimeters to about 3 meters, depending on the technology
 A newer technology, radio frequency identification (RFID), has been
emerging over the past decade as a substitute for bar codes.
 Detectable up to about 3 meters away, RFID tags are identified as
they pass fixed sensors.
 As the tags pass within range of an interrogator (tag reader), their
circuitry is charged either inductively or electro magnetically.
 Industry exploits them for a wide variety of purposes and as a
replacement for bar codes.
 Evidently, current RFID offerings were designed to cover doorways,
where a read range of 3 meters is adequate

15. Current Mid-range Technologies
 A variety of products can be read from a distance of 15 meters or
more
 If a receiver is in range, it detects the tag's presence and notifies a
software application.
 If the tag signal is not received when expected, the system triggers
an alarm
 A mature instance of this technology is produced by BI Inc.,
Boulder, Colo., for Electronic Home Arrest Monitoring (EHAM).
 The systems monitor the homes of persons under court-ordered
supervision, to check whether they are there or not.
 A radio-frequency transmitter fastened around the client's ankle
emits a signal, and a field-monitoring device picks it up

16.  The U.S. Department of Defense also deploys a tagging system,
based on high-end tag technology developed by Savi Technology,
Mountain View, Calif.
 Containers of the kind usable on any form of transport have two-
way radio tags attached to them, and their contents recorded in the
tag's memory
 Several products for identifying locations of objects employ infrared
technology, called IR1D.
 The tags periodically transmit their identification codes by emitting
infrared light to readers installed throughout the facility.
 The tag prices are relatively high, and installation is complicated by
the large number of readers required to ensure a line of sight to every
possible tag.
 Users also complain about reliability. Nonetheless, IRID systems are
currently being sold, mostly for health care applications

17. The 3D-iD system design
 The 3D-iD system was envisioned as the equivalent of a GPS for a
location fixed by boundaries—a building, say, or a parking lot, or an
amusement park; hence the term local positioning system (LPS).
 The system uses the concepts of GPS, but with a proprietary
infrastructure to communicate with inexpensive tags
 In GPS, each satellite transmits a unique code, a copy of which is
created in real time in the user-set receiver by the internal
electronics.
 The receiver then gradually time-shifts its internal code until it
corresponds to the received code—an event called lock-on.
 Once locked on to a satellite, the receiver can determine the exact
timing of the received signal in reference to its own internal clock
 In real GPS receivers, the internal clock is not quite accurate enough

18.  A 3D-iD system requires its own indoor antenna infra-structure
 The system is organized as cells within a building.
 Each cell is handled by a cell controller, which is attached to up to
16 antennas by means of coaxial cables.
 Both the cell controller and the tag are designed to comply with FCC
Part 15 regulations so that no license is needed for operation.
 In operation, the cell controller quickly cycles among antennas,
determining distances to whichever of them are in range of the tag.
 Once this is done for at least three antennas, the tag's location in
space can be estimated
 Without developments in four parallel underlying technologies, 3D-
iD technology would not have been practical

19. Drawback
 Even though buildings and updating the signature database are
much easier in indoor environments than in wide urban areas, the
major drawback of pattern recognition techniques still lies in
substantial efforts needed in generation and maintenance of the
signature database in the view of the fact that working
environment changes constantly.

20. Conclusion
 Indoor geolocation is an emerging technology that needs a
scientific foundation.
 To provide such a foundation we need to characterize the radio
propagation features that impact the performance of indoor
geolocation systems.
 The challenge for TOA-based systems is to develop a signaling
system and infrastructure that is inexpensive to design and deploy,
complies with frequency regulations, and provides a
comprehensive coverage for accurate ranging.

21. Thank You

22. QUERIES