11 Introduction Dr. Miguel A. Labrador Department of Computer Science & Engineering [email protected] labrador

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Introduction

Dr. Miguel A. Labrador

Department of Computer Science & Engineering

[email protected]

http://www.csee.usf.edu/~labrador

2Copyright© Dr. Miguel A. Labrador


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Outline

• Location Based Information Systems (LBIS)• LBIS challenges• Location-Based Services (LBS) applications• Location provider architectures• Software architecture• A complete LBS example



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Location Based Information Systems

• Systems that integrate advances in mobile phones, software development platforms, databases, positioning technology, Geographic Information Systems (GIS), and communications

• All combined make possible the creation of Location-Based Information Systems (LBIS) and Location-Based Services (LBS)– Promise to change the way we live

• 3.25 billion mobile phone users in 2007– Half the world’s population

• LBS subscribers using GPS-enabled cell phones expected to grow from 12 M in 2006 to 315 M in 2011– 20 M from 500 K in North America



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LBIS Challenges

• Many players and technologies involved, and many issues unsolved– Databases, GIS systems, positioning, applications

• Erroneous and variable information– Accuracy of GPS fixes depend on positioning system, user location,

weather conditions, interferences, etc.• Cellular communication networks

– Wireless transmission problems, such as fading, interferences, disconnections, low bandwidth, etc.

• Cell phones– Very resource-constrained device in terms of processing power,

storage, and energy capabilities• Operating systems and interoperability



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Location-Based Services (LBS)

• An application that provides users with information based on the geographical position of the mobile device

• Main difference from other applications/systems– Availability of the user’s position in real-time– This single difference makes a BIG difference

• Initial LBS systems were subscription-based– Traffic congestion notifications based on roads selected from a Web

site– Received congestion updates about I-75 when on travel in NYC!



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Types of LBS Applications

• LBS can be either Reactive (“pull”) or Proactive (“push”)• A Reactive LBS application is triggered by the user who, based

on his current location, queries the system in search of information

• Many examples– Finding restaurants or places of interest– Obtaining directions– Locating people– Obtaining weather information– Sending emergency notifications to police, insurance companies,

roadside assistance companies, etc.



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Types of LBS Applications

• In Proactive LBS applications, on the other hand, queries or actions are automatically generated by the LBIS once a predefined set of conditions are met

• System needs to continuously know where you are and evaluate the predefined conditions

• Many examples as well– Geofencing, e.g., children outside predefined boundary– Fleet management– Real-time traffic congestion notifications– Location-based advertisement– Real-time friend finding– Proximity-based actuation– Travel assistant device for riding public transportation, tourism,

museum guided visits, etc



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Location

• In LBIS and LBS applications everything is about LOCATION• Important to know about different players and techniques used

in the provision of location information• A location provider may or may not be the same entity providing

the location-based service to the user• According to who provides the location information, the system

can be categorized as network-based, mobile-based, and location provider-based



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Network-Based Location Provider

• Usually the same cellular network carrier• Carrier locates the user and stores his location in a database

within its network• LBS provider needs to obtain permission and/or pay for

obtaining user location information• LBS application needs mechanisms to query the DB• Preferred way of cellular carriers

– Maintain ownership and control of the location information– Additional revenues

• Have not accelerated the development of LBS– Cellular networks need to install costly positioning technologies– Carriers may limit the number and frequency of queries

• Limiting the developing of some applications, mostly real-time ones– Applications need to be aware of which carrier the user belongs to



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Network-Based Location Provider



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Mobile-Based Location Provider

• Mobile device has the capability of obtaining the location– GPS, cell network, both

• Location is sent to the LBS service provider and stored in its database for future reference or processing

• Server application may or may not send information back to user– Depends on application and predefined parameters

• Clients are not limited to cellular phones– Any GPS-enabled device with communication capability

• Accelerated rapid development of LBS application– Neither financial nor technical barriers

• Main disadvantage of this method is that it has the potential to flood the network with location updates– Different LBS providers may or may not share the locations– A user may be sending same location to more than one LBS provider



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Mobile-Based Location Provider



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Location Provider-Based

• Meant to solve the flooding problem of mobile-based method• Independent entity collects locations using different methods

and make them available to LBS providers• Only business is to provide location information• Scalable architecture; perhaps the best architecture for wide

deployment of LBS– Provisions needed to guarantee fair price and include competition

• There are a few companies that provide location information – Skyhook, Where, Veriplace, Loc-Aid Technologies, others

– In this class, we will use the mobile-based method • GPS-enabled cell phones and network-based technologies



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Location Provider-Based



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A Complete LBIS Tracking Example

• General real-time tracking application with visualization– Tracking devices, people, etc.

• Uses the mobile-based location provider architecture• Proactive LBS application consisting of the following

components:– Positioning system– Client device– Transport network– Main control station– Servers

• Standard and free software and standard protocols as much as possible



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Hardware

• Positioning system – GPS and Assisted GPS (A-GPS)

• Client device– GPS-enabled cell phone or any device with GPS or embedded

positioning system• Transport network

– Cellular network with data plan (GPRS or similar) or network connectivity using Wi-Fi or any other IP-based networking technology

• Main control station– PC connected to the system to control service and visualize data,

e.g., set up geofence and Google maps• Servers

– Database, GIS for geocoding and reverse geocoding, application server for processing



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Software

• Java platform– Java SE for clients and Java ME for resource-constrained devices

• Sun’s Glassfish as the application server• Google ‘s Web Toolkit for visualization

– Google Maps and Google Earth• Postgres, and object-oriented relational database• PostGIS, Postgres’s add on to support geographic objects• Standard communication protocols

– HTTP, TCP, UDP



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A Complete Tracking System Example



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Software Architecture

• Software architecture is needed in order to – Have an organized system– Know who does what in the system – Understand data flow– Know about relationships between components– Know protocols and interfaces used

• Software architecture for the client and for the server– An example follows – Used in proactive, mobile-based location provider applications

related to transportation



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Software Architecture - Client



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Software Architecture - Server



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A Brief Look into the Future

• LBS, Human-Centric Sensing, Participatory Sensing



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Participatory Sensing

Documents

11 Introduction Dr. Miguel A. Labrador Department of Computer Science & Engineering [email protected] labrador