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 MethodGPS802.11protocolscell towermanual layerL2L2, L3, L7 accuracy10m20-100mroom-level, AP100 m-2 km room 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 problemsmostly 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 use Enterprise & home LANs Some ISPs DSL, cable backup for other methods enterprise home PC

5 Location delivery protocols MethodLLDP-MEDDHCPHELD layerL2L3L7 (HTTP) accuracyroom-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 problems may be hard to automate for large enterprises mapping MAC address to location? mapping IP address to switch port? use Enterprise & home LANs Some 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) environmentalsecurity facility buddy finder instant messaging mobile gamesgeocaching shopping guides travel & tourist guides mobile yellow pages travel planner people & vehicle tracking product tracking directionsindoor routing car park assistance traffic 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 to nearest location-based events subscribe to locations, not people Alice has entered the meeting room subscriber may be device in room

See the city in true realtime: how busy is the city & where is everyone going, right now? Red: all anonymous destination activityGreen: 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.com (alpha consumer app) Aggregate GPS information

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) Nightlife Restaurants Residential Work Minimum Volume Embedding

Platforms missing navigation missing network connectivity

IETF GEOPRIV and SIMPLE architectures target location server location recipient rule maker presentity presence agent watcher GEOPRIV SIP presence PUBLISH SUBSCRIBE publication interface notification interface 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)

15 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 <gml:Point gml:id="point1“ srsName="epsg:4326"> 37:46:30N 122:25:10W no T04:57:29Z T20:57:29Z Presence and privacy: PIDF-LO

16 GEOPRIV privacy rules Conditions identity, sphere time of day current location identity as or + 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