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Location Based Services

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1 Location Based Services
CE Software Development 13/04/2017 Location Based Services What is a Location Based Service? How is a LBS useful? Components What’s special about it? Context Adoption Privacy How does it work? Services request processing Mobile positioning Architectural requirements Lot to get through Lecture 1 - Introduction

2 Introduction to LBS A certain service that is offered to the users based on their location An information service provided by a device that knows where it is and modifies the information it provides accordingly Mobile services that utilise user location information to add value to the service Usually require modifications in either the networks or the mobile device or both It was first developed for the military and emergency services

3 LBS: Then For how many years have we used these signs as the ONLY source for LBS? Version 1.2 Feb 2009

4 LBS: Now Location-based traffic reports:
Range query: How many cars on the motorway? Shortest path query: What is the estimated time travel to reach my destination? Location-based store finder: Range query: What are the restaurants within five miles of my location? Nearest-neighbor query: Where is my nearest fast food restaurant? Location-based advertisement: Range query: Send E-coupons to all customers within five miles of my store

5 It’s 4:30pm and Mum is stuck in traffic
inTouch checks her calendar and sees she’s supposed to pick up Cindy from ballet Version 1.2 Feb 2009

6 Mum’s phone senses that she is in a traffic jam, and automatically prepares a status message
Mum hits “send”, and Cindy sees that Mum is running late. Cindy decides to wait inside.

7 LBS: Why Now ? GIS/ Spatial Database Mobile GIS Web GIS LBS
Internet Mobile Devices GIS/ Spatial Database Web GIS LBS Mobile Internet Mobile GIS LBS is a Convergence of Technologies Version 1.2 Feb 2009

8 LBS Applications Version 1.2 Feb 2009

9 LBS Components (1) Mobile Devices Communication Network
A tool for the user to request the needed information The results can be given by speech, using pictures, text... PDAs, Mobile Phones, Laptops, a car navigation unit, a toll box for road pricing in a truck Communication Network The mobile network Transfers the user data and service request from the mobile terminal to the service provider Transfers the requested information back to the user Version 1.2 Feb 2009

10 LBS Components (2) Positioning Component
For the processing of a service usually the user position has to be determined The user position can be obtained either by using the mobile communication network or by using the Global Positioning System (GPS) Further possibilities to determine the position are WLAN stations, active badges or radio beacons (indoor navigation) If the position is not determined automatically it can be also specified manually by the user Service and Application Provider Responsible for the service request processing Calculation of the position, finding a route, searching yellow pages with respect to position or searching specific information on objects of user interest Version 1.2 Feb 2009

11 LBS Components (3) Data and Content Provider
Service providers will usually not store and maintain all the information which can be requested by users Geographic base data and location information is requested from the maintaining authority (e.g. mapping agencies) or business and industry partners (e.g. yellow pages, traffic companies) Version 1.2 Feb 2009

12 LBS- Context (1) Mobile user identity
Age and gender - children are unlikely to be interested in knowing about bars and pubs Personal preferences – Language, style, imagery, colours Location - the most commonly considered element of context It allows information and services to be localized Time - An entertainment’s active time might be used to determine if an event was still valid, for example a concert or a venue is open Orientation - the direction a user is heading in and thus what is in front, behind and to either side of them In a tourist guide this might be used to determine what historical building the user is facing In a navigation service it is important to check the user is heading in the right direction Version 1.2 Feb 2009

13 LBS- Context (2) Navigation history Purpose of use
allows the users to see where they have been and what they have seen and done orientate a user while they're are moving and allow them to backtrack if they get lost help to build up a profile of the what the user is interested in, enhancing the provision of relevant information Purpose of use Defined by the activities, goals, tasks and roles of users. Different types of usage require different Types of information Types of presentation, for example maps, text or speech, and Modes of interaction Version 1.2 Feb 2009

14 LBS- Context (3) Social and cultural situation Physical Surroundings
proximity to others social relationships collaborative tasks Physical Surroundings lighting level or how much ambient noise there For example direct sunlight will make screens more difficult to read requiring the contrast to be adjusted System Properties to the computer infrastructure the user is employing What type of device they are using and what are its capabilities a continuous internet connection or it is only intermittent, bandwidth, the quality of the positioning information, e.g. the GPS coverage. Version 1.2 Feb 2009

15 LBS- Context How do services respond to context? Information level
Technology level User interface level Presentation level Version 1.2 Feb 2009

16 LBS- Privacy Like many technologies, LBS have an enormous potential for good but they can also be misused. The potential for misuse doesn’t invalidate the technology, but it does mean that we must be thoughtful about how we apply it, especially during its developmental stages. Version 1.2 Feb 2009

17 Major Privacy Threats YOU ARE TRACKED…!!!!
“New technologies can pinpoint your location at any time and place. They promise safety and convenience but threaten privacy and security” Cover story, IEEE Spectrum, July 2003 Version 1.2 Feb 2009

18 Major Privacy Threats

19 How does it Work? Version 1.2 Feb 2009

20 Positioning Methods Version 1.2 Feb 2009

21 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) Hybrid solutions RF Fingerprinting (on phones that will support WLAN) Version 1.2 Feb 2009

22 GPS With the launch of Sputnik in 1957, radio-based global positioning became a (theoretical) possibility TRANSIT This was a very crude form of GPS using only one satellite (1960s) Submarines used it Could only be used every minutes Submarine had to be still Version 1.2 Feb 2009

23 Components of GPS and how it works
Space (e.g. satellites) Control (i.e. a ground station at a known geographic location) User The GPS receiver precisely measures the time it takes a signal to travel from a satellite to the receiver There are lots of satellites Version 1.2 Feb 2009

24 CE51600-1 Software Development
13/04/2017 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. Lecture 1 - Introduction

25 Satellite Triangulation
GPS receiver links to the handset As reference to the nearest 3 satellites the receiver calculates the exact position

26 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 GPS III system will launch in 2014 GPSIII.pdf Should be even more accurate than the 8m accuracy limit currently in place Galileo is a European Union Equivalent Version 1.2 Feb 2009

27 Assisted GPS Conventional GPS has difficulty providing reliable positions in poor signal conditions When first turned on in these conditions, some non- assisted GPS units may not be able to download the information from the GPS satellites 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 Version 1.2 Feb 2009

28 A-GPS Assisted GPS gives improvements in Assistance Data
Time to First Fix Battery Life Sensitivity Cost Assistance Data Satellite Position Time information Visible GPS List Version 1.2 Feb 2009

29 Cell ID (Cell of Origin)
Cell based positioning No calculation Least accurate than others Accuracy is dependent on cell density Compatible with all handset and GSM network Version 1.2 Feb 2009

30 Timing Advance (TA) Power level or time taken at phone logged at Base Station Calculation based on signal loss or time taken for signal travel Compatible with all handset and GSM network Resolution is 500 meters Version 1.2 Feb 2009

31 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 Version 1.2 Feb 2009

32 Time of Arrival (TOA) Location Measurement Units (LMU) at Base Station
Measure access requests from handset Triangulation calculated from combined information Compatible with all handset and GSM network Version 1.2 Feb 2009

33 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 Version 1.2 Feb 2009

34 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 Version 1.2 Feb 2009

35 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 Version 1.2 Feb 2009

36 EOTD – Enhanced Observed Time Difference
Version 1.2 Feb 2009

37 Keyboard Based You set your location! Example: Navigation Software:
Manually set origin Manually set destination Approve when each step is completed to get the next step instructions Version 1.2 Feb 2009

38 Lampposts Based Last Mile 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 Version 1.2 Feb 2009

39 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 Version 1.2 Feb 2009

40 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 Version 1.2 Feb 2009

41 RF Fingerprint Based Version 1.2 Feb 2009

42 Range Of Coverage AGPS,GPS, GPS Hybrids 5 m 100 m EOTD 300 m TDOA, AOA
Cell ID + TA 500 m Cell ID 1000+m Version 1.2 Feb 2009

43 Major Technologies Table
Technology Handset impact Accuracy Cell ID none Depends on the size of the cell 100m-3km Cell ID + TA 500m TDOA m AOA EOTD yes 20-200m GPS/AGPS 5-30m

44 Code of practice Regulation play a major role in the shape and success LBS. Regulation is likely to have an impact on the accuracy operators will provide and the use of handling user information This will affect both technology choice and the availability and usability of user location information for different players Location based service providers that use location data as part of their services must comply with the Industry Code of Practice For the Use of Mobile Phone Technology to Provide Passive Services in the UK wrpsessionid=FvsQQS4S5qMn4RJ02nwbkJLkwpxTbMt59HTgV57QJyt W2BygpZJ6! ?_nfpb=true&_pageLabel=template12&pageID= PRPP_0011 ce.pdf Version 1.2 Feb 2009

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