Location-Based Services Henning by fjwuxn

VIEWS: 525 PAGES: 26

									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
                              Location-
                            determination
                              methods
      Method          GPS                 802.11             protocols            cell tower            manual
layer                                       L2               L2, L3, L7
                                                                                                    room or building
accuracy              10m                20-100m           room-level, AP         100 m-2 km
                                                                                                          AP

                                                         • room-level
               • privacy           • simple to implement
                                                           accuracy
                                                                              •no infrastructure   • no infrastructure
advantages     • global            • reasonably                               cost
                                                         • no surveying                            • privacy
               • accurate            accurate
                                                           needed
                                                                              •client privacy

                                   •requires survey
                                   •only works in urban     mapping IP
                                                                              •low accuracy        •stationary only
problems        mostly outdoors    areas                  address to switch
                                   •requires Internet          port?
                                                                              •cell coverage       •doesn’t scale
                                   connectivity
                                    Enterprise & home
               Enterprise & home                                               backup for other        enterprise
use                                       LANs               DSL, cable
                     LANs                                                         methods              home PC
                                       Some ISPs
Location delivery protocols
      Method        LLDP-MED                     DHCP                 HELD
layer                   L2                         L3               L7 (HTTP)
accuracy          room-level, AP             room-level, AP       room-level, AP

               • simple to implement
                                                • simple to       • traverses NATs
                  • built into switch
advantages                                       implement       • can be operated
                  • direct port/room
                                            • network locality       by L2 provider
                        mapping


                 may be hard to              mapping MAC           mapping IP
problems        automate for large            address to         address to switch
                   enterprises                 location?              port?

                                              Enterprise &
                Enterprise & home
use                                           home LANs          DSL, cable ISPs
                      LANs
                                              Some ISPs




                                        5
                    Location-based
   people &
vehicle tracking
                       services indoor routing       directions          car park
                                                                        assistance
                                                                                              traffic
                                                                                           management

                                                                                                                    emergency
                    Tracking                                                                                          calls
product tracking                                                                           Emergency
                                                           Navigation                                              automotive
                                                                                                                   assistance
   shopping
    guides
                                                                                                                    banners &
 travel & tourist                                                                          Advertising
                                                                                                                      alerts
     guides             Information                        location-
 mobile yellow                                               based
   pages                                                   services                            Billing              road tolling


 travel planner
                                                                                           facility
                          Games                                                                               Infrastructure

   geocaching
                                                       Leisure                Management                        customer
                                                                                                               relationship
 mobile games
                                                                                                                  fleet
                    Communications                                                                            (scheduling)
   location-aware                                                  instant
                                            buddy finder                                   security
    call handling                                                 messaging                                   environmental

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

                                                             6
          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
        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
                            8
            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
      Modes of emergency
       communications
                          emergency call
information
“I-am-alive”
               emergency alert               dispatch
               (“inverse 911”)



                        civic coordination


                        10
Components of NG911
      system

   LoST                 LoST
                      (private)
 (public)
                                      PSAP
                        ESN
                 (county, state, …)



                                      PSAP
 Internet

            11
  LoST: Location-to-URL Mapping
                VSP1   cluster serving VSP1
                                                                                 replicate
                                                                             root information
123 Broad Ave                                               cluster
    Leonia                                                serves VSP2
Bergen County
    NJ US




                                      LoST
                                               NJ                       NY             root
                                               US                       US            nodes
                                                          search
                                                          referral

                                                    Bergen County
                                                        NJ US
      sip:psap@leonianj.gov
                                                                             Leonia
                                                                             NJ US



                                              12
                  LoST Architecture
     tree guide
                                     G
                                                                          G
                   G
                              G             T1: .us
                                                                              broadcast (gossip)




                                          G T2: .de
                  resolver



seeker
313 Westview
Leonia, NJ US



                                                                                     T3
                                                                                    (.dk)
                                                         T2
                                                       (.de)
                              T1
                             (.us)   Leonia, NJ  sip:psap@leonianj.gov
                                                                                   (.dk
                                               13
                                                                                     )
                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>




                                   14
   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>




                                         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.
Aggregate GPS              Now available in San Francisco, more cities rolling out in beta version.
  information
                           Volume Embedding
    Minimumthat determines behavior and clusters from anonymous
Machine learning algorithm
          aggregate movement from all pairs of corners in the city.
           Obtains behavioral map of city (vs. geographical map)




                   Restaurants                                   Work


                         Nightlife                     Residential
Platforms
                     missing location
 missing network
   connectivity


                                time zone



missing navigation

          BlueTooth? ZigBee?
               IETF GEOPRIV and SIMPLE
                      architectures

       DHCP                                      rule
                                 XCAP
                                                maker
                                (rules)

              publication                 notification
                            location                     location
target         interface
                             server
                                           interface
                                                         recipient   GEOPRIV

                                          SUBSCRIBE
                            presence                                    SIP
presentity                                               watcher
              PUBLISH        agent                                   presence
      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


•   All presence data,
                                 <tuple id="sg89ae">
                                   <status>
                                     <gp:geopriv>
    particularly location, is           <gp:location-info>
    highly sensitive                      <gml:location>


•   Basic location object
                                            <gml:Point gml:id="point1“
                                                   srsName="epsg:4326">
                                               <gml:coordinates>37:46:30N 122:25:10W
    (PIDF-LO) describes
    •
                                              </gml:coordinates>
                                              </gml:Point>
       distribution (binary)
    •
                                          </gml:location>
                                        </gp:location-info>
       retention duration              <gp:usage-rules>

•   Policy rules for more
                                         <gp:retransmission-allowed>no
                                          </gp:retransmission-allowed>
    detailed access control              <gp:retention-expiry>2003-06-23T04:57:29Z


    •
                                          </gp:retention-expiry>
       who can subscribe               </gp:usage-rules>
                                     </gp:geopriv>
       to my presence              </status>

    •  who can see what
                                   <timestamp>2003-06-22T20:57:29Z</timestamp>
                                 </tuple>

       when

                                22
            GEOPRIV privacy
•   Conditions
                rules gets maximum of
                   • User
                                                 permissions across all
    •   identity, sphere
                                                 matching rules
    •   time of day
    •   current location                       • privacy-safe composition:
    •   identity as <uri> or <domain> +          removal of a rule can only
        <except>                                 reduce privileges
• Actions                                      • Extendable to new
  • watcher confirmation
• Transformations                                presence data
    •   include information                    – rich presence
    •   reduced accuracy                       – biological sensors
        •   e.g., only within 5 mile           – mood sensors
            radius




                                          23
    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

								
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