Location Based Services
for
Mobile Devices
Embedded Computing Seminar
Shay Horovitz
1
Technologies
2
Location Technologies
•
•
•
•
•
•
•
•
•
•
•
•
•
GPS - Global Positioning System
AGPS - Assisted GPS
Cell ID
Cell ID + Timing Advance
Signal Strength Based
AOA - Angle Of Arrival
TOA - Time Of Arrival
TDOA - Time Difference of Arrival
EOTD - Enhanced Observed Time Difference
Keypad based (click the address yourself)
Camera based (taking pictures of signs)
Hybrid solutions
RF Fingerprinting (on phones that will support WLAN)
3
GPS
4
History
• Mariners relied upon the sun for
latitude, and clocks for longitude
• With the launch of Sputnik in 1957,
radio-based global positioning became
a (theoretical) possibility
5
TRANSIT
• This was a very crude form of GPS
using only one satellite (1960s)
– Submarines used it
– Could only be used every 35-45 minutes
– Submarine had to be still
6
TIMATION (1960s)
• Another satellite (TIMATION I) was
launched to enhance the TRANSIT
system
• Major innovation was the inclusion of an
atomic clock
• Submarines could now be in motion and
use the system
7
NAVSTAR
• In 1973, NAVSTAR began research & development
• 1978 – the first 4 satellites
were launched
• Operated by the
Department of Defense
– Primary mission is to
provide exact coordinates
for land, sea & air-based
military forces
– Cost about
$18,000,000,000 to develop…
so far
8
There are three components of GPS
• 1.) Space (e.g. satellites)
• 2.) Control (i.e. a ground station at a
known geographic location)
• 3.) User
9
How it works
10
Satellites
• The GPS receiver precisely measures the
time it takes a signal
to travel from a
satellite to the
receiver
• There are lots and
lots of satellites
• Anyone want to
11
guess how many?
Details
• 6 orbital planes,
included at 55
degrees to the
equator, each with
4 satellites
– 21 active satellites,
3 backups
• Orbit the earth at
12,541 miles and
have an orbital
period of 11 hrs. 56
min.
12
Satellite Triangulation
13
How many points do you need?
• Using one satellite narrows the distance to a
sphere around the satellite
• Using two satellites, you’ll find your location
within a circle (previous slide)
• Using three satellites limits your location to
only 2 points
– Usually, it is possible to determine which point
• Using four satellites confirms your location
and gives you 2 readings for altitude
– Usually you can determine which is correct
14
The importance of time
• Both satellites and receivers generate
Pseudo Random Noise (PRN)
– A Link 1 (L1) carrier signal is generated at 1575.42
MHz and Link 2 (L2) carrier signal is generated at
1227.60 MHz
• Carrier signals are modulated to produce coded signals,
such as C/A code (at 1.023 MHz) and the P code (at
10.23 MHz)
– The frequencies are frequency-modulated to
produce step-functions
– The codes repeat every millisecond
• The satellites come with cesium or rubidium
clocks
15
Time lag
16
Selective Acquisition
• The US military was concerned about the
possibility of terrorists or other unfriendly
people using GPS to precisely guide a
missile (or other unfriendly device)
• The deliberately introduced errors in the
time embedded in the signal
• This caused locations to be up to 100m
off
• Turned off on 2 May 2000
17
Selective Acquisition
18
2010
• GPS III system will launch
• Should be even more accurate than the
8m accuracy limit currently in place
19
Tech: AGPS
• GPS has a slow time to fix unless it is
permanently tracking satellites
• To solve the inherent restrictions with
GPS, Assisted GPS was proposed
• Assisted GPS is based upon providing
GPS satellite information to the handset,
via the cellular network
20
Tech: AGPS
• Assisted GPS gives improvements in
–
–
–
–
Time to First Fix
Battery Life
Sensitivity
Cost
• Assistance Data
–
–
–
–
Satellite Position
Time information
Visible GPS List
Sensitivity
21
Tech: Cell ID
• Cell ID: the cell that the mobile is
connected to
• Operator’s know where their cell sites are
• Accuracy is dependent on cell density
• Can be implemented both network based
or device based
22
Tech: Cell ID
23
Tech: Cell ID + Timing Advance (TA)
• TA is the time delay between the mobile
and serving base station
• Resolution is 500 meters
• Serving cell identity and TA are available
in networks
24
Tech: Signal Strength Based
• Measure signal strength from the control
channels of several Base Stations
• If signal levels from 3 different BSs are
known, it’s possible to calculate the
location
25
Tech: Signal Strength Based
26
Tech: AOA - Angle Of Arrival
• Measure the angle of arrived signal
between base station and mobile station
• Location error increases as mobile is far
from BSs
27
Tech: TOA - Time Of Arrival
• Measure the time of arrived signal
between base station and mobile station
• Mobile station locates at the intersection
point which will be made by more than 3
circles
28
Tech: TDOA – Time Difference Of
Arrival
• Measure the time difference of arrived
signal between base station and mobile
station : Minimum three base stations
• Mobile station locates at the intersection
point which will be made by more than 3
hyperbolas
29
Tech: TDOA – Time Difference Of
Arrival
30
Tech: EOTD – Enhanced Observed
Time Difference
• Added device, LMU (Location
Measurement Unit), whose location is
known
• LMU and mobile station measure the
time difference of arrived signal from
base station at the same time
• Mobile station locates at the intersection
point which will be made by more than 3
hyperbolas
31
Tech: EOTD – Enhanced Observed
Time Difference
32
Tech: Keyboard Based
•
•
You set your location!
Example: Navigation
Software:
1. Manually set origin
2. Manually set destination
3. Approve when each step
is completed to get the
next step instructions
33
Tech: Camera Based
• Take a picture of road signs and send by
MMS to a server
• 2D Barcodes
34
Tech: Lamposts Based
• Last Mile, a British
company plans to offer
Internet & LBS using
street lampposts…
• A flash memory will be
installed inside the
lampposts and store info
about local pubs, shops.
• Cost: about £500 per
lamppost
35
Tech: Hybrid Solutions Based
• Improve effectiveness
• Extends the coverage of a solution e.g.
AGPS
• Common Hybrids
– EOTD / AGPS
– Cell ID / AGPS
• Benefits of both systems realized
increasing the accuracy and availability
of any single method
36
Tech: RF Fingerprint Based
• Pinpointing wireless clients makes it easier to
secure and manage wireless LANs
• WLANs typically have used closest access
point (closest AP) or triangulation
technologies to track location
• RF fingerprinting improves by taking into
account the effects that a building or people
will have on an RF signal - characteristics such
as reflection, attenuation and multi-path
37
Tech: RF Fingerprint Based
38
Range Of Coverage
5m
AGPS,GPS,
GPS Hybrids
100 m
EOTD
TDOA, AOA
300 m
Cell ID + TA
500 m
Cell ID
1000+m
39
Major Technologies Table
Technology
Handset impact
Accuracy
Cell ID
none
Depends on the size of the cell
100m-3km
Cell ID + TA
none
500m
TDOA
none
100-200m
AOA
none
100-200m
EOTD
yes
20-200m
GPS/AGPS
yes
5-30m
40
Applications
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Network Optimization
In-Car & Personal Navigation and wayfinding
Emergency (E911)
Monitoring traffic flow using device location & optimization
Automated Mapping
Family Tracking/ Find-A-Friend
Find the Nearest Store/place
Tourist Information/Automated Guide
Live public transport info
Games
Fleet Management
Location-based Billing
Demographic Statistics
Target Marketing
Other applications
41
LBS based games
42
Game: Glofun RayGun
- Location: US
- Target: Ghost-Hunting!
- Use of GPS for location of player
43
Game: SS+K Conqwest
• Location: 5 cities in the USA
• Team-based treasure hunt in the urban jungle
• 5 teams searching for treasure in the form of
“printed codes” – 2d barcodes that can be
captured by phonecam
• 1 code=1$. First team to find $5000 worth
codes wins and earns a $5000 scholarship
for their school…
44
Game: Blisterent Swordfish
• GPS based game
• You play against a virtual
school of Swordfish
• See where’s the nearest school
of virtual fish
45
Game: Blisterent Torpedo Bay
• A-GPS based game
• No GPS reception? Predictive positioning…
• Use of real map
• 360 degrees view
46
Game: NewtGames Mogi
• Location: Tokyo, Japan
• GPS based
• Pick up virtual items spread on the
whole of Japan
• At a range of 400m, you’re able to
collect an item
47
Game: Mikoishi GunSlingers
• Location: Singapore
• Cell-ID based
• Multiplayer shooting game
48
HP Labs City Tags
•
•
•
•
Location: Bristol, UK
iPaq PocketPC with GPS, Wifi needed
Social interaction: Tag people
When got tagged, need to find a friend
to free you
49
GeoCaching
• Take something from the cache
• Leave something in the cache
• Write about it in the logbook
50
Geocaching
51
Developer Toolkits
• Chips:
– HammerHead
– TI
– Intel
• APIs:
– Sun J2ME Location API
– Qualcomm BREW LBS API
52
Chips Market
"The mobile GPS semiconductor market
is expected to exceed 180 million units
in 2008 …" Will Strauss, president of
Forward Concepts
[http://www10.edacafe.com/nbc/articles/view_article.php?section=ICNews&articleid=223846]
53
HammerHead: PMB 2520
•
•
•
•
Single chip solution
A-GPS Implementation
Size: 80 mm2
Low Power
54
TI Chip: NaviLink 4.0 GPS5300
• Single chip solution
• Smallest A-GPS (50 mm2)
• Low Power, Power Management
• Production: 2Q, 2006
55
TI Chip: NaviLink 4.0 GPS5300
56
Intel’s Plans
• “Notebook chips will likely support
location-based services by 2006, Intel
says. “ PCWorld
[http://www.itworld.com/Comp/2085/041025pentiumm/]
57
SUN J2ME LBS
• Location API for J2ME (JSR 179)
• A set of generic APIs for developing
LBS
• Can support GPS/A-GPS/Cell-ID/any
other method [by implementing a
location provider]
58
SUN J2ME LBS sample
59
Chips in detail
60
Typical GPS Receivers Power Usage
Name
SiRFstar I
SiRFstar I/LX
CPU
Fab
Proce
ss
Volta
ge
(volts
)
Motorola MC68330
at 19.1 mhz
0.60
5
Hitachi
SH-1 7021 RISC at 12.2
mhz
0.35
3.3
SiRFstar IIe
ARM7/TDMI
12.3 mhz
SiRFstar
IIe/lp
ARM7/TDMI
12.3 (?) mhz
SiRFstar IIt
ARM7/TDMI
12.3 (?) mhz
2.7
?
2.7
2.7
Average Power Usage (mW)
Average
1,700
165
165
65
45
61
Some interesting numbers…
• Most popular chipset – SiRF
• Smallest modules:
– SyChip GPS2020: 13x15x3.8
– Trimble M-Loc MPM: 25x25x6.5
– Fastrax iTrax02: 26x26x6.5
• Smallest module with integrated
Antenna – Axiom Swift A1: 41x41x11
62
Use One?
• Ready made External boxes with
integrated antennas or separate
• Support USB / RS232
• Available as both PCMCIA and
Compact Flash cards
63
Chip Sets 1
Dims.
mm
Sup/Curr
.
V/mA
BT1575 RF front end
QLP32
2.4-3/
Zodiac 2000 chip set Scorpio
Baseband Processor and
Monopac RF front end
or CX74010 RF front end or
CX76502 RF MCM
CX11239 optional HW
accelerator
Monopac:
PQFP80
BBP1202 baseband processor
TQFP100
Company
Product
Analog Devices
NAV 2300 chipset.
ADSSTRF2000 RF Down
converter
ADSST NAV 2300 based
Correlator and Navigation
Processor
Picture
BethelTronix, Inc.
Conexant (Rockwell)
EverMore
3.3/
64
Chip Sets 2
Company
Magellan
Motorola
Parthus
Product
Picture
Dims.
mm
G10 gps chip
Sup/Curr.
V/mA
3.3/115
MG2000 Mixed
mode GPS RF downconverter and 12channel digital
correlator
BGA64
2.7-3.6/20
GPS chip set.
MRFIC1504 RF front
end
MMC2003 controller
LQFP48
LQFP144
2.7-3.3/27
3-3.6/
NavStream platform
HW and SW
24x40x10
LQFP
3/
3/
UAA1570HL RF
SAA1575HL
LQFP48
LQFP100
2.7-5/60
3-5/50
SAF1576 single chip
gps.
QUAD-44
3/?
Phillips
65
Chip Sets 3
Dims.
mm
Sup/Curr.
V/mA
SiRFstarI GSP 1/LX,
GRF1/LX front end,
GSW1/LX SW.
GRF1: LQFP32,
GSP1: LQFP100
BGA144
3.3/150
SiRFstarII GSP2e digital
section, GRF2i RF front
end, GSW2e SW.
GRF2i:
LQFP48
LPCC32,
GSP2e:
TQFP100
BGA144,160
LQFP144
3/160
SiRFstarIIt ext. host,
GSP2t digital section,
GRF2i RF front end,
SiRFNav SW.
GRF2i:
LQFP48
GSP2t:
LQFP48
3/57
Company
Product
RF Micro
Devices, Inc.
RF2460 LNA/Mixer,
EGR-X001, ACS-X001
transceivers
SiRF
Picture
66
Chip Sets 4
Dims.
mm
Sup/Curr.
V/mA
Sony Semiconductor
CXA1951AQ RF front end
CXD2931R baseband
processor
QFP40
LQFP144
2.7-5.5/30
3-3.6/55
STMicroelectronics
STB5600 RF Front End
ST20-GP6 Baseband
Processor
TQFP32
PQFP100
3.3-5.9/35
3.3/45
Trimble
FirstGPS (Infineon based)
IO - PMB 2500 Baseband
Correlator
Colossus -- PMB 3330 RF
Front-end
TSSOP28
TSSOP24
3.3/2.5
2.7/8
Valence Semiconductor
VS7001 gps front end
TQFP48
2.7-3.3/14
Zarlink Semiconductor
GP2015 RF Front End
GP4020 Baseband
Processor
TQFP48
LQFP100
3-5/70
3.3/100
Company
Product
Picture
67
Modules 1
Dims.
mm
Sup/Iidle
V/mA
GPS accessory combined battery/gps for
cell. phones (SiRF based)
103x46x19
3.7/1.4Ah
LiIon
NAV-2300 GPS receiver board
50x40x12
3.3/180
G8 oem receiver (8 chan. only)
(Phillips based)
39x60x10.
4
5/140
G12 oem receiver
108x57x?
5/360
Company
Product
Airbiquity
Analog
Devices
Picture
Ashtech
68
Modules 2
Company
Axiom Navigation
Inc.
Dims.
mm
Sup/Iidle
V/mA
Swift A2 oem GPS receiver (SiRF
based)
integrated ceramic patch
antenna
42x42x
3.3/150
Swift B2 oem GPS receiver (SiRF
based)
25x32x7
3.3/150
SUPERSTAR II gps oem receiver
46x71x13
3.3/150
TU70-D100 GPS sensor board
integrated patch antenna
61x54x14.5
3.3/
Jupiter receiver boards
71x41x11
3.3,5/130
Product
Picture
Sandpiper oem GPS receivers
(SiRF based)
CMC Electronics Inc.
Conexant (Rockwell)
69
Modules 3
Dims.
mm
Sup/Iidle
V/mA
Crux II GPS engine D154N
(SiRF based)
41x52x?
3.3,5/160
GM-X205 oem module
w/antenna
55x40x20
3.8-8/105
EB-X305 oem module
70x40x10
3.3/130
iTRAX02 GPS receiver
26x26x4
2.7-3.3/37
Company
Product
EMTAC
Picture
EverMore
Fastrax
70
Modules 4
Dims.
mm
Sup/Iidle
V/mA
GPS 25 Series gps engine
46.5x70x11.4
3.6-6/115
JGG20 GPS, INMARSAT,
WAAS, and GLONASS
108x57x16
4-14/500
TF10 receiver module (SiRF
based)
42x72x12
3.3,5/180
TF 30 receiver module (SiRF
based)
30x40x7
3.3/140
TF 50 GPS and GLONASS
module
71x51x12
3.3/180
Company
Product
Garmin
Javad Navigation Systems
Picture
Laipac Tech
UV-40 16-chan. receiver
module
3.3/?
71
Modules 5
Company
Motorola
RF Micro Devices, Inc.
Dims.
mm
Sup/Iidle
V/mA
M12 Oncore GPS
Receiver
40x60x10
2.7-3.2/75
SL Oncore GPS
Receiver
(8 chan. only)
40x80x12.2
5/150
GT Plus Oncore GPS
Receiver
(8 chan. only)
51x83x16.3
5/150
RF8000 12-ch. module
38x38x9.8
3.3/100
Product
Picture
72
Modules 6
Company
Rojone
RoyalTek
Dims.
mm
Sup/Iidle
V/mA
Genius 3 (SiRF based) integrated
antenna
66x66x7
5/180
Genius 4 (SiRF based)
66x66x7
5/180
Micro Genius 3
40x35x10
3.3/160
REB-12R Series gps engine (SiRF
based)
41x71x11.5
3.3(5)/180
REB-2101 gps board (SiRF based)
40x36x8
3.3/170
RGM-3000 gps board (SiRF
based)
21x28x13
3.3/170
Product
Picture
73
Modules 7
Company
Sena GPS SA
Sigtec
Navigation Pty
Ltd
Dims.
mm
Sup/Iidle
V/mA
Albatros OEM
gps receiver
(SiRF based)
11x29.5x38
3.3(5)/135
Proteus OEM
gps receiver
(Mitel based)
50x120x19
9-32/220
MG5001 OEM
GPS Receiver
66x47x12
3.3/150
Product
Picture
autoNAV
MG5002 Designed for
external
microprocessor.
cellNAV
MG5003 Designed for use
in cellphones.
microNAV
MG5004 General purpose,
optimised for
small size
74
Modules 8
Company
Product
GXB2100 Module
Sony Semiconductor
SyChip
Picture
Dims.
mm
Sup/Iidle
V/mA
36.5x25x?
3.3/?
GXB3000 Module
3.3/?
GXB3100 Module
3.3/?
GPS2020 receiver module
(SiRF based)
13x15x3.8
3.3/145
Lassen SK-II gps module
83x31x10.2
5/95
Lassen LP gps module
66x32x12
3.3/55
Lassen SQ gps module
26x26x6
3.3/30
M-Loc MPM gps module
25x25x6.5
3.3/10.5
Trimble
75
Modules 9
Company
u-blox
Valence Semiconductor
Dims.
mm
Sup/Iidle
V/mA
TIM gps module
(SiRF based)
25x25x3
3.3/140
GPS-MS1E gps
module (SiRF based)
30x30x7.7
3.3/140
GPS-PS1E gps
module (SiRF based)
32x82x7.7
5/140
Product
VS7001-REF 3B/3D
ref. module
Picture
3.3/?
76
Build your own ?
77
GPS Building Blocks 1
•
Antenna element
–
–
•
Low Noise Amplifier (LNA)
–
–
–
•
Cost: $3 to $300 (depends on single/double frequency reception & phase center
stability)
Diameter: 2cm to 15cm
Amplifies GPS signals
Cost: $5 to $100 (depends on number of frequencies & quality of filters)
Power consumption: 20mW to 200mW
RF section
–
–
–
–
Converts received signal to digital form
Cost: $5 to $200 (depends on number of frequencies & quality of filters)
Size: 2-20 cm
Power consumption 100mW to 1 Watt
78
GPS Building Blocks 2
• Digital section
– Processes the digital samples and provides tracking measures
– Cost: $5 to $15
• Microprocessor
– Control the tracking elements based on measurements and doppler
(range rate change)
– Collects navigation data about the orbit and clock of each satellite
– Compute position
– Support interfaces to the user
– Cost: $5 to $50
– Power consumption: 200mW to 3W
79
GPS Building Blocks 3
• Processor Peripherals
– Provide memory for program and data storage
– Cost: $5 to $100 (depending on capacity and speed)
– Power consumption: 100mW to 2W
• I/O & Drivers
– Serial/ Parallel/ USB/ Ethernet/ other comm ports
– Cost: $2 to $20
– Power consumption: 10mW to 100mW
80
References
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Ronald Azuma et el., “Recent Advances in Augmented Reality”, IEEE Computer Graphics
and Applications, vol.21, no.6, Nov/Dec 2001, pp.34-47
Mohammad S. Sharawi et el., “Investigation into the performance of EOTD for GSM users in
Telematics applications”, Proceedings of SPIE, vol. 5084, Aug. 2003, pp.6-18
http://yona_n.tripod.com/gps/gps-survey.html#chips
EDN: http://www.edn.com/article/CA243219.html
GPSWorld: http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=15100&pageID=1
HowStuffWorks: http://electronics.howstuffworks.com/gps.htm
http://www.symbian.com/developer/techlib/papers/messaging/LocalAwareness_LBS_01.pdf
http://www.terena.nl/conferences/tnc2005/core/getfile.php?file_id=453
LBS Market: http://www.trueposition.com/lrc/LBSLongTimeComing.pdf
LBS Forecast: http://mms.ecs.soton.ac.uk/mms2002/papers/4.pdf
Location Technologies:
http://developer.openwave.com/omdtdocs/location_studio_sdk/pdf/Intro_to_Location_Techn
ologies.pdf
GSM LBS:
http://www.ftw.at/ftw/events/telekommunikationsforum/WS2001/WS01docs/020111.ppt
E-911: http://www.sss-mag.com/e911.html
Solutions: http://www.wirelessdevnet.com/channels/lbs/features/mobilepositioning.html
GPS Based games: http://www.glofun.com/
LBS in Europe: http://www.hottelecom.com/berginsight-lbs.html
81
Thank You
For Listening
82