Transcript Foundations of Location

Location-Based
Services
Henning Schulzrinne
Columbia University
Overview
• Time + space
• Getting location information
• Using location information
• Privacy issues
Getting location
information
• Universal
• anywhere in the world
• independent of network connectivity
• Non-proprietary
• Energy efficient
• Accurate to 10 m/room level
doesn’t exist in one system
Locationdetermination
methods
Method
GPS
layer
accuracy
advantages
10m
• privacy
• global
• accurate
802.11
protocols
L2
L2, L3, L7
20-100m
room-level, AP
• room-level
• simple to implement
accuracy
• reasonably
• no surveying
accurate
needed
•requires survey
•only works in urban
problems
use
mostly outdoors
Enterprise & home
LANs
areas
•requires Internet
connectivity
Enterprise & home
LANs
Some ISPs
mapping IP
address to switch
port?
DSL, cable
cell tower
manual
100 m-2 km
room or building
AP
•no infrastructure
cost
•client privacy
•low accuracy
•cell coverage
backup for other
methods
• no infrastructure
• privacy
•stationary only
•doesn’t scale
enterprise
home PC
Location delivery protocols
Method
LLDP-MED
DHCP
HELD
L2
L3
L7 (HTTP)
room-level, AP
room-level, AP
room-level, AP
• simple to implement
• built into switch
• direct port/room
mapping
• simple to
implement
• network locality
• traverses NATs
• can be operated
by L2 provider
problems
may be hard to
automate for large
enterprises
mapping MAC
address to
location?
mapping IP
address to switch
port?
use
Enterprise & home
LANs
Enterprise &
home LANs
Some ISPs
DSL, cable ISPs
layer
accuracy
advantages
5
Location-based
services
indoor routing
people &
vehicle tracking
car park
assistance
directions
traffic
management
emergency
calls
Tracking
product tracking
Emergency
Navigation
automotive
assistance
shopping
guides
travel & tourist
guides
Information
locationbased
services
mobile yellow
pages
travel planner
Advertising
banners &
alerts
Billing
road tolling
facility
Games
Infrastructure
geocaching
Management
Leisure
customer
relationship
mobile games
fleet
(scheduling)
Communications
location-aware
call handling
instant
messaging
buddy finder
security
Foundations of Location-based Services (Steinger, Neun, Edwardes), modified)
6
environmental
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•
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Location-based
services
Finding services based on location
•
•
physical services (stores, restaurants, ATMs, ...)
electronic services (hot spots, printers, ...)
Using location to improve (network) services
•
incoming or outgoing communications adapts to location
Using location to provide information
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•
tourist guides
advertisements
Making others aware of user location
•
•
presence (individual)
popularity, movement (group)
Security
•
grant access based on user’s location
Location-based VoIP
services
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Location-aware inbound routing
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•
•
do not forward call if time at callee location is [11 pm, 8
am]
only forward time-for-lunch if destination is on campus
do not ring phone if I’m in a theater
outbound call routing
•
•
contact nearest emergency call center
send [email protected] to nearest branch
location-based events
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•
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subscribe to locations, not people
Alice has entered the meeting room
8
subscriber may be device
in room
•
Location-based
security
Examples:
Garmin GPS unlocks at home
Only allow person in room to control
conference room equipment via web
browser
Restrict access to bank account based on
user’s location
IP-address based (MaxMind, ...)
Need certified location
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Modes of emergency
communications
emergency call
information
“I-am-alive”
emergency alert
(“inverse 911”)
civic coordination
10
dispatch
Components of NG911
system
LoST
(public)
LoST
(private)
PSAP
ESN
(county, state, …)
PSAP
Internet
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LoST: Location-to-URL Mapping
VSP1
cluster serving VSP1
replicate
root information
cluster
serves VSP2
123 Broad Ave
Leonia
Bergen County
NJ US
LoST
NJ
US
root
nodes
NY
US
search
referral
Bergen County
NJ US
sip:[email protected]
Leonia
NJ US
12
LoST Architecture
G
tree guide
G
G
G
T1: .us
G T2: .de
broadcast (gossip)
resolver
seeker
313 Westview
Leonia, NJ US
T3
(.dk)
T2
(.de)
T1
(.us)
Leonia, NJ  sip:[email protected]
13
(.dk
)
LoST: Query example
<findService xmlns="urn:…:lost1”
recursive="true" serviceBoundary="value">
<location profile="basic-civic">
<civicAddress>
<country>Germany</country>
<A1>Bavaria</A1>
<A3>Munich</A3>
<A6>Neu Perlach</A6>
<HNO>96</HNO>
</civicAddress>
</location>
<service>urn:service:sos.police</service>
</findService>
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LoST “Find Service” response/warning example
<findServiceResponse xmlns="urn:ietf:params:xml:ns:lost1">
<mapping expires=“1990-12-31T23:59:60Z” lastUpdated=“2006-11-01T01:00:00Z”>
<displayName xml:lang="de">München Polizei-Abteilung</displayName>
<service>urn:service:sos.police</service>
<serviceBoundary profile=”civic”>
<civicAddress xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>Germany</country>
<A1>Bavaria</A1><A3>Munich</A3><PC>81675</PC>
</civicAddress>
</serviceBoundary>
<uri>sip:[email protected]</uri>
<serviceNumber>110</serviceNumber>
</mapping>
<path>
<via source=“lost:esgw.uber-110.de.example”/>
<via source=“lost:polizei.munchen.de.example”>
</path>
</findServiceResponse>
15
Citysense.com
See the city in true realtime: how busy is the city & where is everyone going, right now?
Red: all anonymous destination activity Green: only unusual destination activity
Press “1” to see the #1 hottest destination, then “1” again to see the restaurants and bars there, etc.
Now available in San Francisco, more cities rolling out in beta version.
GPS
Aggregate
information
Minimum Volume Embedding
Machine learning algorithm that determines behavior and clusters from anonymous
aggregate movement from all pairs of corners in the city.
Obtains behavioral map of city (vs. geographical map)
Restaurants
Work
Nightlife
Residential
Platforms
missing network
connectivity
missing location
time zone
missing navigation
BlueTooth? ZigBee?
IETF GEOPRIV and SIMPLE
architectures
DHCP
XCAP
(rules)
target
presentity
publication
interface
PUBLISH
location
server
presence
agent
rule
maker
notification
interface
location
recipient
GEOPRIV
watcher
SIP
presence
SUBSCRIBE
Privacy issues
• Not all LBS are privacy-sensitive
• “where is the the M125 bus?”
• navigation with GPS
• Problem: location + personal identity
• or derivable (e.g., via home location)
Privacy threats
reveal device anonymously
(e.g., “nearest gas station”)
Privacy
reveal identity + location to LBS
(friend finder service)
reveal to individual
(friend, other)
Presence and privacy: PIDF-LO
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All presence data,
particularly location, is
highly sensitive
Basic location object
(PIDF-LO) describes
distribution (binary)
retention duration
Policy rules for more
detailed access control
who can subscribe
to my presence
who can see what
when
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<tuple id="sg89ae">
<status>
<gp:geopriv>
<gp:location-info>
<gml:location>
<gml:Point gml:id="point1“
srsName="epsg:4326">
<gml:coordinates>37:46:30N 122:25:10W
</gml:coordinates>
</gml:Point>
</gml:location>
</gp:location-info>
<gp:usage-rules>
<gp:retransmission-allowed>no
</gp:retransmission-allowed>
<gp:retention-expiry>2003-06-23T04:57:29Z
</gp:retention-expiry>
</gp:usage-rules>
</gp:geopriv>
</status>
<timestamp>2003-06-22T20:57:29Z</timestamp>
</tuple>
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GEOPRIV privacy
rules
• User gets maximum of
Conditions
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permissions across all
matching rules
• privacy-safe composition:
removal of a rule can only
reduce privileges
• Extendable to new
presence data
identity, sphere
time of day
current location
identity as <uri> or <domain> +
<except>
• Actions
• watcher confirmation
• Transformations
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•
– rich presence
– biological sensors
– mood sensors
include information
reduced accuracy
e.g., only within 5 mile
radius
•
23
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Open technical and
standards issues
Universal APIs
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As simple as gettimeofday()
Not specific to method or vendor
Crowd-sourcing
Integration between presence and location
•
presence as universal third party interface?
Clear privacy rules
•
both technical and legal
Deployment issues
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ISPs need to make location available to their
customers
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for in-door use
location as a chargeable service?
LAN-based location for room-level location
•
•
APs and ports
enterprise
Conclusion
• Location as fundamental service
•
•
building block → time & space
Improve user experience
from navigation and locating services
to automatic silent mode
Need network protocols for
conveying location
mapping location to services
describing privacy requirements
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