mobile computing and ad hoc network

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  • Introduction Mobile Computing


  • What is Mobile Computing?


  • Mobile Computing Device Display Only Info Pad model: limited portable processing Like a cordless phone. Laptop Computer ThinkPad model: significant portable processing, operates independently of wireless infrastructure. Personal Digital Assistant [PDA] : Somewhere between these extremes. a handhelddevicethat combines computing, telephone Internet andnetworking.features.


  • Mobile computing device

  • Mobile StationsA mobile stations (MS) comprises all user equipment and software needed for communication communication with a mobile network. The term refers to the global system connected to the mobile network, i.e. mobile phone or mobile computing connected using a mobile broadband adapter. The is the terminology of 2G system like GSM.GSM network comprises of many functional units. These can be broadly divided into The mobile stations The base Station subsystemThe network switching subsystem

  • GSM Architecture

  • Mobile Station(MS)

    The Mobile Station is made up of two entities:Mobile Equipment (ME)Subscriber Identity Module (SIM)

  • Mobile Equipment (ME)

    Portable, vehicle mounted, hand held device.Uniquely identified by an IMEI (International Mobile Equipment Identity).Voice and data transmission.

  • Subscriber Identity Module (SIM)

    Smart card contains the International Mobile Subscriber Identity (IMSI)Allows user to send and receive calls and receive other subscribed servicesProtected by a password or PINCan be moved from phone to phone contains key information to activate the phone

  • Base Station Subsystem (BSS)

    It consists of 2 major hardware components:Base Transceiver Station (BTS)Base Station Controller (BSC)

  • Base Transceiver Station (BTS)

    The BTS contains the RF components that provide the air interface for a particular cell .Encodes, encrypts, multiplexes, modulates and feeds the RF signals to the antenna.Communicates with Mobile station and BSC.Consists of Transceivers (TRX) units.

  • Base Station Controller (BSC)

    Provides the control for the BSS. Communicates directly with the MSC. May control single or multiple BTS.In charge of handovers, frequency hopping, exchange functions and control of power level of BTS.

  • Network Switching Subsystem(NSS)

    The system contains the following functional units

    Mobile Switching Center (MSC)Home Location Register (HLR) Visitor Location Register (VLR)Authentication Center (AUC)Equipment Identity Register (EIR)Operation and maintenance center (OMC)


  • Mobile Switching Center (MSC)

    Central component of NSS.MSC performs the switching functions.Each MSC provides service to MS located within a defined geographic coverage area.

  • Home Location Register (HLR)

    Stores information about each subscriber that belongs to its MSC in permanent and temporary fashion.As soon as mobile subscriber leaves its current local area, the information in the HLR is updated.Database contains IMSI, prepaid/postpaid, roaming restrictions and supplementary services.

  • Visitor Location Register (VLR) The Visitor Location Register (VLR) contains the information about subscriber parameters and location information for all mobile subscribers currently located in the geographical area controlled by that VLR. Authentication Center (AUC)It is used for security purposes. Authentication is a process to verify the subscriber SIM. AUC & HLR collectively authenticate the subscribers.

  • Equipment identity register (EIR) Stores all devices identifications registered for this network. Database that is used to track handsets using the IMEI.White or Valid list Grey or Monitored list Black or prohibited list Operation and maintenance center (OMC) The Operation and maintenance Center (OMC) is the centralized maintenance and diagnostic heart of the base station system (BSS). It allows the network provider to operate, administer , and monitor the functioning of the BSS.

  • Stations Flow Diagram

  • Roaming Overview

    Roaming is an ability to access mobile data and voice services even if subscriber is outside the coverage area of HOME Network.It is possible via using VISITED Network services.To provide roaming facility to subscribers, operators should have roaming agreement with the other operators in different places.

  • Benefit of GSM technology in Roaming

    GSM Roaming, which involves roaming between GSM networks, offers the convenience of a single number, a single bill and a single phone with worldwide access to over 191 countries. The convenience of GSM Roaming has been a key driver behind the global success of the GSM Platform.

  • Roaming overview

    Cell phoneSwitch

    City 2 (Visited Area) Subscriber is on Roaming.City 1 (Home Area) Subscribers own area where they are using its own providers servicesSwitch

    Cell phoneHome Operator - Hutch AreaVisited Operators Area (Roaming Partner of Hutch)

    MSCHutch Network InfrastructureHutch SubscriberRoaming Agreement Present between Hutch and other OperatorsHutch Subscriber but using other operator services for Roaming purpose

    MSCOther operators Network Infrastructure

  • Roaming Scenarios

    Caller - Hutch RoamerOther Operators NE

    City 2 (Visited Area) Subscriber is on Roaming.City 1 (Home Area) Subscribers own area where they are using its own providers servicesHutch NEReceiver of HutchHome Operator - Hutch AreaVisited Operators Area (Roaming Partner of Hutch)

    HUTCH MSCHutch Network InfrastructureRoaming Agreement Present between Hutch and other OperatorsHutch Subscriber but using other operator services for Roaming purpose

    MSCOther operators Network InfrastructureHutch User Receiving Hutch Roamer CallScenario 2- When roamer makes calls to his Home Network (HPLMN), he obviously knows that he is temporarily out of his home network and thus his calls are routed through his temporary home network ie. visited network (VPLMN).

  • Inbound and Outbound RoamingAssuming Airtel as a home operatorInbound Roaming - Customers of other operator roaming in Airtel area and using Airtel infrastructure then this activity is called inbound roaming. Only those customers can roam in Airtel network whose operator has Inbound Roaming agreement with Airtel.

    Outbound Roaming - Outbound Roaming refers to Airtel customers roaming in network of other operators area. Customers of Airtel can roam in network of other operators with whom Airtel has Outbound Roaming agreement.

  • Wired Vs. Mobile NetworksWired Networks- high bandwidth- low bandwidth variability- can listen on wire- high power machines- high resource machinesMobile Networks- low bandwidth- high bandwidth variability- hidden terminal problem- low power machines- low resource machines


  • Types of Wireless DevicesLaptopsPalmtopsPDAsCell phonesPagersSensors


  • Advantage of Wireless NetworksFlexible: Radio waves can penetrate the obstacles. Sender and receiver can be placed any where. Mobility: Data can be access from any location.Robustness : Can survive in disaster (Earthquake, military operations)Scalable: Can be configured in variety of topologies. Easy InstallationLess Cost


  • Disadvantage of Wireless NetworksQuality of Service: Lower Bandwidth Lower Data Transmission RateHigh Error RatesInterferenceHigher Delay


  • Application of Mobile ComputingFor Estate Agents In courts In companies Stock Information Collection/Control Credit Card Verification Taxi/Truck Dispatch Electronic Mail/Paging


  • Future Aspects3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services. GPS (Global Positioning System) The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather, anywhere on or near the Earth. Long Term Evolution (LTE) LTE is a standard for wireless communication of high-speed data for mobile phones and data terminals. Its related with the implementation of forth Generation (4G) technology.WiMAX (Worldwide Interoperability for Microwave Access) technology. Near field communication (NFC)

  • conclusionMobile computing has severe limitations- however, it is far from impossible, and technology improves all the timeLots of challenges- some have (good) solutions, many others are still waiting to be solved

  • Ad Hoc Network

  • Introduction to Ad Hoc networkIt is a type of MHWNs.Nodes in the network are mobile in general.The wireless hosts in such networks, communicate with each other without the existing of a fixed infrastructure and without a central control.A mobile ad-hoc network can be connected to other fixed networks or to the Internet.Most of the Ad-Hoc networks use the allocated frequencies for the Industrial, Scientific and Medical (ISM) band.

  • Flow diagram of Ad Hoc Network



  • Applications of AdHoc network

    Group of people with laptops and they want to exchange files and data without having an access point.

    Incase if we need to exchange information and the network's infrastructure has been destroyed.

    It is suitable for military communications at battlefield where there is no network infrastructure.

    Sharing the internetConnected to the internet


  • Advantages of AdHoc Network

    Ad-hoc networks can have more flexibility.It is better in mobility.It can be turn up and