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Location Based Services in Telecommunication Networks


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This is a presentation which describe the big picture of the Location Based Services and its applicability in Telecommunication Networks . In this presentation I simply describe the theories with practical examples. Hope this presentation will cover the overall Location Based Services in Telecommunication Networks domain.

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Location Based Services in Telecommunication Networks

  1. 1. 1 Copyright to Rohana K Amarakoon @
  2. 2. 1876 Telephone 1980 FAX 1995 Internet 1999 e-Everything 2000 m – GIS and LBS 2 Copyright to Rohana K Amarakoon @
  3. 3. Past Most of this income is coming from Short Message Services (SMS) Later MMS, IM, email and mobile Internet (Wireless Application Protocol [WAP]) Now Tracking user & applications. (LBS Services) 3 Copyright to Rohana K Amarakoon @
  4. 4. services that integrate a mobile device’s location or position with other information so as to provide added value to a user. Location Based Services (LBS) In 1970s, the U.S. Department of Defense has been operating the global positioning System (GPS), a satellite infrastructure serving the positioning of people and objects. In 1980s, U.S. government decided in to make the system’s positioning data freely available to other industries worldwide. History 4 Copyright to Rohana K Amarakoon @
  5. 5. Definitions Definition 1 : LBSs are information services accessible with mobile devices through the mobile network and utilizing the ability to make use of the location of the mobile device. (Virrantaus 2001) Definition 2 : A wireless-IP service that uses geographic information to serve a mobile user. Any application service that exploits the position of a mobile terminal. (Open Geospatial Consortium (OGC, 2005)) 5 Copyright to Rohana K Amarakoon @
  6. 6. Military & Government Industries Emergency Services Commercial Sector Air traffic control Sea port control In-car navigation Freight management 6 Copyright to Rohana K Amarakoon @
  7. 7. A two way communication and interaction User : tells the information he needs, preferences and position Provider : deliver information tailored to the user needs Provider to answer : Where am I ? What is near by ? How Can I go to ? 7 Copyright to Rohana K Amarakoon @
  8. 8. GPS (NAVSTAR) Galileo GLONASS Types of Satellites provides LBS 8 Copyright to Rohana K Amarakoon @
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  15. 15. 1980 1990 2000 2005 MarketSize $1 Billion $5 Billion $10 Billion GIS Market Internet and Mobile Location Services Market Inflection Point Time 15 Copyright to Rohana K Amarakoon @
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  20. 20. Person Oriented (ex : friend finder application) Device Oriented Major Classification Cell phone Palm top Lap-top Kiosk Car-based computer Cell antenna Mobile device Display 20 Copyright to Rohana K Amarakoon @
  21. 21. Push Services Pull Services Other Classification The information may be sent to the user with prior consent or without prior consent User actively uses an application and, in this context, ‘‘pulls’’ information from the network 21 Copyright to Rohana K Amarakoon @
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  23. 23. Perception of being observed. Location based spam messages. Unsolicited messages pushed to mobile phones (may be perceived as even more harmful than email spamming) European Union Policy (Directive 2002/58/EC) 23 Copyright to Rohana K Amarakoon @
  24. 24. Positioning Layer : Responsible for calculating positions of device or user. Application Layer : offer the services requested by applications. Middleware Layer : Reduce the complexity of service integration. 24 Copyright to Rohana K Amarakoon @
  25. 25. Location middleware can be used to manage interoperability between networks for location date. 25 Copyright to Rohana K Amarakoon @
  26. 26. Digital Maps Point of interest information Data Capture & Collection Dynamic Data Concierge application use business and landmark info Point of Interest Information (POI) POI Data collected from multiple vendors merge in to single DB Each record in POI DB is geo coded 26 Copyright to Rohana K Amarakoon @
  27. 27. Dynamic data capabilities server LBS engines because they allow dispatches to react almost instantaneously to changing conditions Dynamic Data Geo coding & reverse geo coding Location Engine Routing Proximity searches 27 Copyright to Rohana K Amarakoon @
  28. 28. Standard based tool set need API that adhere to industry standards such as C, Java, XML. 28 Copyright to Rohana K Amarakoon @
  29. 29. Future mobile devices will be used more frequently to access dynamic and personal geo-relevant content. LBS technology and applications will be key driver of the mobile service market. 29 Copyright to Rohana K Amarakoon @
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  32. 32. Navigation systems guide objects moving from one place to another have progressed recently with the rapid advances in positioning, communication, and spatial data storage and processing technologies. The easy availability of satellite-based global positioning systems has revolutionized all forms of automated navigation : LBS provide the ability to find the geographical location of a mobile device and then provide services based on that location. LBS application services provide the ability to find the geographical location of a mobile device and then provide services based on that location. The core services are location utilities services, directory services, presentation service, gateway service, and route determination service. The Spatial DB act as a backend server to the geo mobility server. 32 Copyright to Rohana K Amarakoon @
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  34. 34. Integrated collection of position and orientation sensors and computing and communication H/W and S/W. Navigation systems cover a broad spectrum of integrated technologies that allow accurate determination of the geographic coordinates of the (moving) objects, their velocity, and height. LBS uses accurate and real-time positioning systems and GIS to determine the location of a moving object. The OGC recently initiated the OpenLS standard to address the technical specifications for LBS. The core of LBS applications is the back-end SDB server, which provides efficient storage, management, and processing capabilities for geospatial data. The SDB server provides dynamic information on demand to aid automated navigation. 34 Copyright to Rohana K Amarakoon @
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  36. 36. Essential component for building efficient navigation system application. Conceptual Data Model Logical Data Model Physical Data Model It acts as a back-end SDB server to the GeoMobility server. 36 Copyright to Rohana K Amarakoon @
  37. 37. Open Location Server is to produce open specification, for interoperable location application services that will integrate spatial data and internet services infrastructure. Geo Mobility Server provide deliver and service location based applications. Location Utility Services - Geo Coding - Reverse Geo Coding Directory Service (Point of location - Interest) Presentation Service (Visualize the spatial data) Gateway Service ( Obtain position of mobile terminal from the N/W) Route Determination Service 37 Copyright to Rohana K Amarakoon @
  38. 38. Data Quality should be high. ( relative accuracy and precision of a particular GIS DB. Lineage Narrative of sources materials used and procedures applied for produce the product. Position Accuracy Defines expected error in position of features. Attribute Accuracy Completeness 38 Copyright to Rohana K Amarakoon @
  39. 39. High level conceptual data model Logical modeling (related to the actual implementation of conceptual data model) Physical design (implementation of the db applications) 39 Copyright to Rohana K Amarakoon @
  40. 40. Interface between the Open Location Services Platform and Mobile Positioning Servers through which the platform obtains near real-time position data for mobile terminals. Stand-Alone positioning system ‘‘current position’’ with reference to a ‘‘starting position”, direction mapped from start point (speed and direction calculate) Satellite based positioning system (NAVSTAR) using 3 parts this will provide the service. Space segment (satellite) User segment (GPS receiver) Control segment (Monitoring stations) 40 Copyright to Rohana K Amarakoon @
  41. 41. Terrestrial ( Radio based positioning system) Systems are designed for specific applications (e.g., offshore navigation) and are generally managed by government and military/naval agencies. Terrestrial positioning systems commonly; Employ direction or angle of arrival (AOA) Absolute timing or time of arrival (TOA) Differential time of arrival (TDOA) techniques to determine the position of a vehicle. 41 Copyright to Rohana K Amarakoon @
  42. 42. Geo Coding Assigning an latitude and longitude coordinates to a given address. Reverse Geo Coding Find the address through the latitude and longitude coordinates. 42 Copyright to Rohana K Amarakoon @
  43. 43. LBS provides a search capacity for one or more Points of Interests (POI) A POI is a place, product or service with a fixed position, identified by name. Point Query (PQ) Range Query (RQ) Nearest Neighbor Query (NNQ – use KNN algorithm) 43 Copyright to Rohana K Amarakoon @
  44. 44. This address finding route and navigation between locations. New Routes Alternative Routes Path Query Processing Determining shortest path between two locations. Dijkstra’s algorithm, IDA, SMA & Best first A* algorithm used here. 44 Copyright to Rohana K Amarakoon @
  45. 45. Currently, most presentation services are provided, based on visual interfaces framework. In future audio guidance along with visual. Centralized Model Traveler communicates with a management counter, which traces the traveler location, speed and other info. It is the management center’s responsibility to compute the route and broadcast this info to the traveler. Distributed Model Route computation is performed by the guidance unit at the hand of the traveler, those need high computational ability. 45 Copyright to Rohana K Amarakoon @
  46. 46. Middleware consists of set of services Exposing interfaces Programming model Interaction model ( to the application developer) 46 Copyright to Rohana K Amarakoon @
  47. 47. LBS broken-down in to B2C B2B 47 Copyright to Rohana K Amarakoon @
  48. 48. Infotainment services ( Finder apps & information request apps – pull based info) Tracking services (Supply chain & inventory, vehicle & people tracking – push & pull info) Selective info dissemination (Targeted content dissemination – push based info) Location based games Emergency support service (119, Ambulance, Fire brigade - need middleware) Location sensitive billing ( call billing, toll payment, purchase good and services – no special middleware support) 48 Copyright to Rohana K Amarakoon @
  49. 49. Push and Pull Based Applications Push – request are initiated by the mobile terminal Pull - infrastructure autonomously and proactively pushes info to mobile 49 Copyright to Rohana K Amarakoon @
  50. 50. Push and Pull Based Applications 50 Copyright to Rohana K Amarakoon @
  51. 51. Direct vs Indirect Profile Personalized application correlates a services request with requester profile information. Direct – gather info from user Indirect – gather info from third parties Availability of profile information Profile info can be available always or on specific time in the LBS 51 Copyright to Rohana K Amarakoon @
  52. 52. Interaction Scenarios The interacting entities, mobile terminals and LBS more generally speaking, service requester and service provider can be either mobile or stationary. Both requester and provider are stationary. Conventional info services are good example for this category. Either be requester or provider are mobile and stationary, respectively their interpolation and instantiation depends on how the application is modeled. Both requester and provider are mobile, LBS take on the role of coordinator. Source of Location Information Queried by LBS application or be transmitted by the mobile terminal. Accuracy of Location information ( This model depends on the infrastructure) 52 Copyright to Rohana K Amarakoon @
  53. 53. LBS middleware platform do : Manage the mobility inherent to all LBS applications by supporting disconnected operations and supporting mobility awareness in the middleware. Manage changes in the underlying N/W topology. Manage millions of info of both consumers and subscriptions. Manage potentially very large no of information providers. Manage highly volatility of users interests. Perform accounting and securing functions. Support privacy consideration, allowing subscribers to opt for the propagation if their location info to selected applications only. Support high rate of inputs (NEWS, location info per user) 53 Copyright to Rohana K Amarakoon @
  54. 54. Set of services that facilitates the development and deployment of distributed applications in heterogeneous environments. The objective of a middleware system are to abstract details of the underlying O/S, N/W and protocols Standard API give rise to application portability and system interoperability LBS middleware is more specialized. It aims at facilitating the deployment and development of LBS applications in heterogeneous N/W environments 54 Copyright to Rohana K Amarakoon @
  55. 55. LBS middleware is deployed within the N/W operator’s H/W or hosted by an application service provider: Connects Consumers on; Mobile terminals & internet 3rd party application providers N/W operators to offers single location based application portal Integrates with; N/W infrastructure (location services, WAP gateways, subscription portal services) Customer care, customer activation services Billing systems, accounting systems 55 Copyright to Rohana K Amarakoon @
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  58. 58. Publish / Subscribe These apps organized as a collection of co-operating components, consisting of producers, which interact by publicizing events and consumers, which subscribe to specific events they are interested in. Two Dimensions: Expressiveness of the data model (subscription language and publication model) Architecture of the event broker The public / subscribe middleware model is inherently, Asynchronous Anonymous (no need to know clients) Multipoint (many clients) Implicit & Stateless 58 Copyright to Rohana K Amarakoon @
  59. 59. Publish / Subscribe paradigm is well suited for modeling selective information dissemination tasks. Publish/subscribe system model to support location-based services 59 Copyright to Rohana K Amarakoon @
  60. 60. Subject Spaces Is a generic system model to express asynchronous interactions of decoupled entities. It is similar to public (subscriber style interactions) The objective of subject space is to provide a precise of the behavior of publish / subscribe systems Subject spaces are used for categorizing publication and subscriptions. 60 Copyright to Rohana K Amarakoon @
  61. 61. Tuple Spaces This model’s primary strength is it’s ability to coordinate many concurrent activities, including the stateful interaction among multiple activities. Tuples are typed data elements, designated as actuals, if the contain data values, and as formals. Tuples can be dynamically inserted, read and removed from the tuple space, but they can’t altered while in the space. update and changes to tuples can be done, first removing the tuple from he space, update it and insert back. All communication is performed via the tuple space, also referred as generative communication 61 Copyright to Rohana K Amarakoon @
  62. 62. Tuple Spaces Operations out (t): Insert tuple in to tuple space in (t): Extracts a tuple matching tuple template t from the tuple space rd (t): equivalent to in(t) , expected than matching tuple is copied and not removed from the tuple space eval(..): Generate active tuples that turn into (passive) tuples, as the associated computations terminate 62 Copyright to Rohana K Amarakoon @
  63. 63. Tuple Spaces Operations In the location based application, information producer and information consumer interact via a space by inserting and extracting tuples. The tuple space decouples the communication between the producer and the consumer. DMBS Based Model This model supports a pull style interaction scheme. A mobile terminal initiated request is evaluated on a database and any results are returned to the requester. 63 Copyright to Rohana K Amarakoon @
  64. 64. The delivery of LBS in practice depends on the existence of a well following value chain. At a value chain begins with content providers. Weather data Traffic data The content integrator manages content received from multiple sources. It maintain a db and IT infrastructure that are capable of capturing the content received. The db making the content available to LBS offered by multiple service providers. Types of content Geographic Infrastructure Other real data (POI data) 64 Copyright to Rohana K Amarakoon @
  65. 65. All the real content, also turned business data, encompasses any content that may reference, directly or in directly the geographic infrastructure. Special-purpose geographic information system (GIS) software manages the geo content general-purpose relational database management system (RDBMS) manages the real content In LBS, the special-purpose GIS world and the general-purpose relational data management world need to be integrated. 65 Copyright to Rohana K Amarakoon @
  66. 66. Several data management challenges exist in relation to LBS. Modeling Update Content Representation of Content Querying of Content Content in static is problematic, dynamic content designed to accommodate updates. Content is more or less dynamic. Representation of Infrastructure. Content capture Content representation, update and querying Display Representation integration 66 Copyright to Rohana K Amarakoon @
  67. 67. Multiple external infrastructure representations. Road centric representation Graph representation Geo representation Internal Infrastructure Representation Competing the other external representations to this representation. Internal representation uses three tables. Element (Element ID) Connections (Connection ID) Element connections (Element ID) 67 Copyright to Rohana K Amarakoon @
  68. 68. Kilometer post representation Road table and kilometer post table used for this. Graph representation Road N/W is an abstraction. Node table and link table used for this. Geo references Summary of infrastructure representation Content modeling Modeling different aspects of infrastructure, 68 Copyright to Rohana K Amarakoon @
  69. 69. Content modeling Elements are related to everything else, so is the content. 69 Copyright to Rohana K Amarakoon @
  70. 70. Updates could be performed efficiently, preliminary by ensuring that the same data are not represented multiple times. Update caused by discrete change Many updates would be needed if the social secure no were used as primary key. Update caused by continuous change. Movement by linear function User movement infrastructure representation Client side caching 70 Copyright to Rohana K Amarakoon @
  71. 71. Update caused by continuous change. Position Tracking 71 Copyright to Rohana K Amarakoon @
  72. 72. Fundamental technique for modeling transportation infrastructure. Linear referencing concepts Linear elements Any geometric shape feature that can be given a meaningful start point Events – points and linear Linear referencing method How location along or beside a linear elements is measured. 72 Copyright to Rohana K Amarakoon @
  73. 73. Linear referencing in oracle Line string (continuous geometry) Multiline string (unconnected line string) Polygon (line string which has starts and ends at the same point) 73 Copyright to Rohana K Amarakoon @
  74. 74. Information and communication technology standards are critically important to the commercial rollout of LBS and fulfillment of their potential. Standards are important to LBS users. Individuals and corporate customers are new beginning to purchase, location based emergency services location based advertising location based games location responsive instant messaging systems LBS to be integrated in to their current billing as just another set of phone charges. Standard are important to LBS providers “Billing one and selling it many times.” 74 Copyright to Rohana K Amarakoon @
  75. 75. 75 Copyright to Rohana K Amarakoon @
  76. 76. When we use location services, we are depending on technologies that can do following. Provide us with wireless communications Provide us with determination Store, serve and apply geo referenced (location, related) data in response to queries. Standards are important in LBS for the same reason they are important in other markets. They help, Providers deliver usable products Services while saving time Money and reducing business risk 76 Copyright to Rohana K Amarakoon @
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  78. 78. LBS standards benefits providers in the LBS value chain by enabling the following Increased billable utilization of carrier’s spectrum and wireless network. Niches for providers with special products and services. A business case for different content providers. Expansion of LBS from a niche service to a mass market service. These standards will be the road map for the definition of an industry and its customer driven deployment of mass market services and content by carriers and internet service suppliers like AOL or Microsoft. Because of several technologies and industries are involved, the standards picture is more complex. 78 Copyright to Rohana K Amarakoon @
  79. 79. Open mobile alliance (OMA) Open GIS consortium (OGC) Location interoperability forum (LIF) Year 2000 – Motorola, Ericson and Nokia started this, purpose is to developing and promoting industrial common solution for LBS 79 Copyright to Rohana K Amarakoon @
  80. 80. LIF’s mobile location protocol (MLP) enables location applications to interoperate with the wireless N/W’s MLP supports privacy and authentication that user’s whereabouts are protected. WAP is also a part of OMA, which provide wireless internet standards, communication. 80 Copyright to Rohana K Amarakoon @
  81. 81. Developed by OGC 81 Copyright to Rohana K Amarakoon @
  82. 82. Organizations which provide standards Cellular Telecommunications & Internet Association (CTIA) Third Generation Partnership Project2 (3GPP2) Automotive Multimedia Interface Consortium (AMIC) 82 Copyright to Rohana K Amarakoon @
  83. 83. OGC members have cooperatively developed the Geomobility server (GMS) Open interfaces for LBS middleware (OGC2) Mobility Mobile Devices Mobile S/W components Interoperability of geomobility enables LBS platform providers and content providers to provide their S/W and data to multiple carriers. The geomobility server is an open service platform comprising the core services developed under the OGC OpenLS initiatives. 83 Copyright to Rohana K Amarakoon @
  84. 84. The goal is to enable communication of location, route, type of service. The primary objective of OpenLS is to define access to the core services and abstract data types (ADT) that comprise the geomobility server. 84 Copyright to Rohana K Amarakoon @
  85. 85. Geo mobility server provides open interfaces to core services for LBS Route determination Determine the route and navigation information between location Location utility Geocoder and reverse geocoder Presentation Showing map, route, POI and route instructions Gateway Get position from the mobile terminal Directory services ( search of POI) 85 Copyright to Rohana K Amarakoon @
  86. 86. Route Metadata pertaining to a route Route instruction List Provides turn by turn navigation instructions Location Position Area of interest Point of interest Address Map 86 Copyright to Rohana K Amarakoon @
  87. 87. Satellite Positioning System Indoor Positioning System Networked Based Positioning System 87 Copyright to Rohana K Amarakoon @
  88. 88. Location based services must be able to detect the location of a mobile user. Introduction satellite based positioning system such as GPS achieve high coverage and precision, but they fail indoor environment. position is an important function for many areas like , - land surveying - aviation - aeronautic - robotic - virual / augmented reality positioning system for LBS used to provide considerable coverage and to allow the location of mobile users with small mobile devices or badges. 88 Copyright to Rohana K Amarakoon @
  89. 89. Coordinate System that describe a 3D worldwide unique location can be divided into two classes: LLA - Latitude - Longitude - Altitude ECEF - Earth Centered - Earth Fixed - zero point of gravity These are serve as reference frames for coordinate systems. Famous model is WGS 84 (world geodetic survey 1984) Scope A positioning system has a certain scope and defines an area of potential coordinates. 89 Copyright to Rohana K Amarakoon @
  90. 90. Coverage The actual coverage of a location system may be smaller than the area of potential locations specified by the scope Precision Users and services that access location data must be aware of inaccuracy. Geographic vs Semantic Locations Users of the LBS interested in meaning of the location instead of coordinates. Semantic location rather than a powerful representation for a great amount of LBS. Additional Spatial Data 90 Copyright to Rohana K Amarakoon @
  91. 91. Determine the location of mobile user Tracking Positioning (mobile system determine the location) Tracking and positioning are based on the following techniques, Cell of the origin (COO) positioning system has a cellular structure, wireless transmitting use for this. Time of Arrival (TOA) Time difference of arrival (TDOA) – (electromagnetic signal used) Angle of Arrival (AOA) Measuring the signal strength Processing video data 91 Copyright to Rohana K Amarakoon @
  92. 92. Advantages Positioning can in principle be carried out everywhere on the earth. Environmental conditions, such as the weather, have only minimal influence on the positioning process. A high precision is obtained. Disadvantages Considerable costs arise for launching and supervising the satellites. The positioning only works if the user receives a sufficient number of satellites 92 Copyright to Rohana K Amarakoon @
  93. 93. Basic principles We need at least three satellites to determine the user’s location in three dimensions. 93 Copyright to Rohana K Amarakoon @
  94. 94. GPS (NAVSTAR-GPS) Started in 1970s, Navigation systems with timing and ranging – Global Positioning System. Department of Defense (DOD) Department of Transportation (DOT) National Aeronautics and Apace Administration (NASA) 94 Copyright to Rohana K Amarakoon @
  95. 95. GPS segments User Segment Contains the devices of the mobile users. GPS receivers can be plug in cards or separate devices can be plug in cards separate devices with a several interface connections. Space Segment (consists of the satellites) 95 Copyright to Rohana K Amarakoon @
  96. 96. GPS segments Control Segment Administration of the satellites as well as for correction of the satellites internal data. 24 satellites move on 6 orbits with 4 satellites per orbit. Satellite need 12 hours for complete a complete orbit. For the usage user don’t need to register and it is free of charge. 96 Copyright to Rohana K Amarakoon @
  97. 97. GPS services Precise Positioning Service (PPS) Military purpose (22m x 27.7m square for 24 hours) Standard Positioning Service (SPS) General usage (100m x 156m for 24 hours) 97 Copyright to Rohana K Amarakoon @
  98. 98. Distortion for GPS services Clock errors. Although the clocks in the satellites work exactly, clocks cause an error of 1.5m in the position calculation. Fluctuations of the orbits. (error of 2.5 m) Disturbances of the atmosphere. (error of 0.5 m) Disturbances of the ionosphere. (error of 5 m) Multipath error. (error of 0.6 m) 98 Copyright to Rohana K Amarakoon @
  99. 99. DGPS and WAAS DGPS (Differential GPS – error corrections) WAAS (Wide Area Augmented System) 99 Copyright to Rohana K Amarakoon @
  100. 100. Satellite signals cannot use for positioning in buildings. Because signals can’t penetrate solid walls. So indoor positioning technologies. Infrared beacon Radio beacon (RFID) Ultrasound system 100 Copyright to Rohana K Amarakoon @
  101. 101. Video Based System 101 Copyright to Rohana K Amarakoon @
  102. 102. GPS is really costly. To reduce cost, existing wireless N/W can be need for positioning services, using cell ID of BST we can do this. TOA and AOA also help to delimitation of the position. GSM Each phone has registered SIM. Which contain info about user and store them in VRL (Visitor Location Register) When user info passed to central DB called HLR (Home Location Register) Each cell phone operator has HLR. City Range 1Km , Countryside Range – 35Km 102 Copyright to Rohana K Amarakoon @
  103. 103. Erricson developed a system called MPS (Mobile Positioning System) which makes more exact positioning possible in large cells The mobile participant can query for location dependent data (Ex: restaurants) Users can supervise the location of other mobile users. Route planning can be done. 103 Copyright to Rohana K Amarakoon @
  104. 104. To compute the positions, MPS use. Cell of Global Identity (CGI) Use the identification of a cell roughly, determine the position. Segment Antennas Base station often have antennas, which divide the 360 in o segments. Timing Advance BST and mobile terminals use certain time slots for communication Uplink Time of Arrival (UL-TOA) by measuring the signal runtimes from a mobile terminal to the base station, the position can be determine with a precision of 50m to 150m. 104 Copyright to Rohana K Amarakoon @
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  106. 106. 106 Copyright to Rohana K Amarakoon @
  107. 107. On top of the transmission, mobile communication system can be constructed in many different ways, serving many different purposes. LBS can be built on top of many different system architectures. Choice of Transmission Medium Connection between two communicating peers Availability of Infrastructure Wireless communication does have limited range, But mobile communication need long range communication. Infrastructure Based Systems Ad-hoc Multihop System Hybrid System 107 Copyright to Rohana K Amarakoon @
  108. 108. Infrastructure Based Systems To overcome wireless communication limited range issues, wired Infrastructure introduced. Each BST cover a certain Area, for each terminal In this area, the base station Ensure that data can be, Transmitted. Structure of a cellular, infrastructure based communication system 108 Copyright to Rohana K Amarakoon @
  109. 109. Ad-Hoc or Multihop System In have terminals are not all in mutual communication range of each other. So middle can act as a relayer of each other. For data coming from one terminal and forward the message towards its destination. Message travels several radiohops. A common characteristic of both single and multiple ad-hoc N/W is the need to be self oriented in setting up and maintaining the N/W. 109 Copyright to Rohana K Amarakoon @
  110. 110. Hybrid System Infrastructure based and a-hoc multihop N/W can be combined. Adding such multihop communication to cellular N/W is powerful way to widen the coverage area of base station or increase the capacity of single cell. 110 Copyright to Rohana K Amarakoon @
  111. 111. GSM – (Global system for mobile communication) UMTS – (Universal mobile telecommunication system) WLAN – (Wireless local area networks) 111 Copyright to Rohana K Amarakoon @
  112. 112. Wireless communication has two essential problems to solve. How to communicate data between a source and a destination. How to organize multiple sources that want to send at the same time. Wireless communication between a single sender and receiver 112 Copyright to Rohana K Amarakoon @
  113. 113. Mobile communication use 800 MHz to 5 GHz range There are legal restrictions and reservation for other applications too (Digital radio or television broadcasting) 900 – 1800 MHz are used for large scale, outdoor communication systems. 2.4 – 5 GHz used for medium and short range communication systems. 113 Copyright to Rohana K Amarakoon @
  114. 114. Mobile communication should provide full coverage. The phone calls should have the quality of fixed network calls, necessitating good quality of service support. First Generation Analog mobile communication systems did not meet all of the above requirements 114 Copyright to Rohana K Amarakoon @
  115. 115. Second Generation GSM N/W architectural overview 115 Copyright to Rohana K Amarakoon @
  116. 116. Between generations – GSM Extensions High Speed Circuit Switched Data (HSCSD) Easily enables higher data rates by bundling several modern connections in single logical connection Enhanced data raes for GSM Evolution (EDGE) General Packed Radio Service (GPRS) This overcome the circuit switched communication. This used packet switching technology. 116 Copyright to Rohana K Amarakoon @
  117. 117. Third Generation – UMTS Tight integration of traditional voice and data applications. 117 Copyright to Rohana K Amarakoon @
  118. 118. Internet is the second largest communication in the world 118 Copyright to Rohana K Amarakoon @
  119. 119. IEEE 802.11 – WLAN Family 802.11a – orthogonal frequency division multiplexing 802.11b – direct sequence spread spectrum Internet Based Mobile Communication In a N/W based on the internet protocol suite, a terminal is identified by its IP address. Ad-Hoc Networking Use multi-hop communication Location Based Service Discovery Ex :- WIFI enabled laptop might want to get a printout which close by printer which also WIFI enabled 119 Copyright to Rohana K Amarakoon @
  120. 120. Problems of LBS Discovery Request for services are flooded through the entire network When the network size grows, flooding becomes unattractive In some type of networks having an identifiable service discovery node can be undesirable 120 Copyright to Rohana K Amarakoon @
  121. 121. For more information E-mail : Blog : Twitter : @MaxRohana 121 Copyright to Rohana K Amarakoon @