Location-Based ServicesHenning SchulzrinneColumbia 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 leveldoesn’t exist in one system

Location-determination

methodsMethod GPS 802.11 protocols cell tower manual

layer L2 L2, L3, L7

accuracy 10m 20-100m room-level, AP 100 m-2 kmroom or building

AP

advantages•privacy•global•accurate

•simple to implement

•reasonably accurate

•room-level accuracy

•no surveying needed

•no infrastructure cost•client privacy

•no infrastructure

•privacy

problems mostly outdoors

•requires survey•only works in urban areas•requires Internet connectivity

mapping IP address to

switch port?

•low accuracy•cell coverage

•stationary only•doesn’t scale

useEnterprise & home LANs

Enterprise & home LANs

Some ISPsDSL, cable

backup for other methods

enterprisehome PC

5

Location delivery protocolsMethod LLDP-MED DHCP HELD

layer L2 L3 L7 (HTTP)

accuracy room-level, AP room-level, AP room-level, AP

advantages

•simple to implement

•built into switch•direct port/room

mapping

•simple to implement•network

locality

•traverses NATs•can be

operated by L2 provider

problemsmay be hard to

automate for large enterprises

mapping MAC address to location?

mapping IP address to

switch port?

useEnterprise & home

LANs

Enterprise & home LANsSome ISPs

DSL, cable ISPs

6

Location-based services

Foundations of Location-based Services (Steinger, Neun, Edwardes), modified)

location-based

services

Information

Tracking

Navigation

Games

Leisure

Billing

Emergency

Advertising

Management

emergency calls

automotive assistance

banners & alerts

road tolling

customer relationship

Infrastructure

fleet (scheduling)

environmental

security

facility

buddy finderinstant

messaging

mobile games

geocaching

shopping guides

travel & tourist guides

mobile yellow pages

travel planner

people & vehicle tracking

product tracking

directionsindoor routingcar park

assistancetraffic

management

Communications

location-aware call handling

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

• tourist guides

• advertisements

• Making others aware of user location

• presence (individual)

• popularity, movement (group)

• Security

• grant access based on user’s location

8

Location-based VoIP services

• Location-aware inbound routing

• 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 delivery@pizza.com to nearest branch

• location-based events

• subscribe to locations, not people

• Alice has entered the meeting room

• 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

10

Modes of emergency communications

emergency call

civic coordination

emergency alert(“inverse 911”)

dispatch

information“I-am-alive”

11

Components of NG911 system

LoST(public)

LoST(private)

Internet

ESN(county, state, …)

PSAP

PSAP

12

LoST: Location-to-URL Mapping

clusterserves VSP2

NYUS

NJUS

Bergen CountyNJ US

123 Broad AveLeonia

Bergen CountyNJ US

cluster serving VSP1

replicateroot information

searchreferral

rootnodes

LeoniaNJ US

sip:psap@leonianj.gov

VSP1

LoST

13

LoST Architecture

T1

(.us)

T2

(.de)

T3

(.dk)

(.dk)

G

G

GG

G broadcast (gossip)

T1: .usT2: .de

resolver

seeker313 WestviewLeonia, NJ US

Leonia, NJ sip:psap@leonianj.gov

tree guide

14

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>

15

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:munich-police@example.com</uri> <serviceNumber>110</serviceNumber> </mapping> <path> <via source=“lost:esgw.uber-110.de.example”/> <via source=“lost:polizei.munchen.de.example”> </path></findServiceResponse>

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.

Citysense.comAggregate

GPS information

Machine learning algorithm that determines behavior and clusters from anonymousaggregate movement from all pairs of corners in the city.

Obtains behavioral map of city (vs. geographical map)

Nightlife

Restaurants

Residential

Work

Minimum Volume Embedding

Platforms

missing navigation

missing networkconnectivity

missing location

BlueTooth? ZigBee?

time zone

IETF GEOPRIV and SIMPLE architectures

target locationserver

locationrecipient

rulemaker

presentitypresence

agent watcher

GEOPRIV

SIPpresencePUBLISH

SUBSCRIBE

publicationinterface

notificationinterface

XCAP(rules)

DHCP

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

Privacy

reveal device anonymously(e.g., “nearest gas station”)

reveal identity + location to LBS(friend finder service)

reveal to individual(friend, other)

22

• 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

<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>

Presence and privacy: PIDF-LO

23

GEOPRIV privacy rules

• Conditions• identity, sphere

• time of day

• current location

• identity as <uri> or <domain> + <except>

• Actions• watcher confirmation

• Transformations• include information

• reduced accuracy

• e.g., only within 5 mile radius

• User gets maximum of permissions across all matching rules

• privacy-safe composition: removal of a rule can only reduce privileges

• Extendable to new presence data

– rich presence– biological sensors– mood sensors

Open technical and standards

issues• Universal APIs

• 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• ISPs need to make location available to

their customers

• 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