Mobile Data Services and Technologies

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Chapter 3

• Mobile Data Services and Technologies

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Mobile Data Services
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Contents

• The RAM/Mobitex mobile data service
• The ARDIS/Modacom mobile data service
• Cellular Digital Packet Data (CDPD)
• Data over analog and digital cellular
• Competing mobile data services
• Paging and two-way paging
• Comparison of paging and cellular

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The RAM/Mobitex Mobile Data Service

• This service is owned jointly by Bell South and
  RAM in the US
• Protocol was developed by Ericsson
• Data rate
• 8 Kbps in the US -gt19.2 Kbps (CDPD)
• 9.6 Kbps in the other parts of the world

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Some of early applications

• Point of sale where dial-up is not available
  MasterCard
• Inventory control of rental cars National Car
  Rental
• Train exchange yards Conrail
• Passenger check-in British Airway
• Field service GE consumer service
• Public safety Chicago Parking Authority
• Insurance claims
• Transportation
• E-mail

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Countries that installed Mobitex networks

• Australia
• Canada
• Finland
• Netherlands
• Norway
• Sweden
• UK
• US

• Rest of Europe (later)
• Latin America (later)
• The Pacific Rim (later)

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What would you need to use the RAM/Mobitex network

• Hardware
• Radio
• Modem
• Terminal
• Application SW
• System integrators
• Software companies

• Network usage
• Mobitex
• Remark the combination unit of radio and modem
  is called Mobidem

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Specifications of Mobidem

• Portable wireless modem and radio
• Connectible to RS-232 serial port
• 8 Kbps migrating to 19.2 Kbps
• 1 pound
• 3.3X2.68X7.87 in
• Max transmit power 2 W
• gt10 hours per battery charge
• Support for nationwide roaming

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Operations of Mobitex

• The Mobidem automatically registers with the
  nearest base station
• The network is a store-and-forward network
• The Mobidem scans the network for incoming
  messages
• It alerts the users of incoming messages
• The Mobidem stores the messages if the terminal
  is not available
• The network stores the messages if the Mobidem is
  not available

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Subscription Type for the Hosts

• CCITT X.25
• ISO/HDLC
• SNA 3270
• Mobitex asynchronous communications

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Subscription Types for the Mobile Terminal

• Continuous linkage to a particular terminal
• Personal subscription that is linked to a person,
  not a terminal, in which case the user logs in
  via name and password
• Group subscriptions that can consists of mobile
  and fixed users

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Mobitex Partners

• IBM
• HP
• Motorola
• Intel
• Fujitsu
• Ericsson
• ATT

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Developer and System Integrator Partners

• DEC
• Lotus
• Novell
• WordPerfect

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The ARDIS/Modacom Mobile Data Service

• Countries have installed Modacom
• US
• Germany
• UK
• Hong Kong
• Data rate
• US 4.8 Kbps -gt 19.2 Kbps (CDPD)
• The other parts of the world 9.6 Kbps

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Applications of Modacom

• Field techniques can access
• Dispatch info.
• Diagnostic info.
• Service history
• Parts availability
• Messenger service
• Receive and dispatch messages while making
  deliveries
• Notify customer that delivery was done

• Salesperson can
• Obtain latest product specifications
• Provide accurate price quote
• Check product availability
• Make the order
• Additional applications
• Fleet management
• Insurance and financial services
• Real time data applications
• Point of sale (POS)
• Telemetry
• E-mail

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InfoTAC

• The radio and modem combination
• Specifications
• Connects through RS-232 port
• Receives, stores, and responds to messages
• Canned responses can be programmed
• 10 KB buffer
• Transmit power 3 W

• 6.8X3.3X3.3 inches
• 18 ounces
• 4X20 line backlit LCD display
• 8 hours battery life
• Compatible with
• ARDIS/Modacom
• RAM/Mobitex

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Cellular Digital Packet Data

• Consortium of companies
• IBM
• 6 of the 7 ROBCs (Regional Bell Operating
  Companies)
• Ameritech Mobile Communications
• Bell Atlantic Mobile Systems
• NYNEX Mobile Communications
• Pac Tel Cellular
• Southwestern Bell Mobile Systems
• US West New Vector Group
• McCaw Cellular Communications
• Contel Cellular
• GTE Mobile Communications

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Four CDPD Applications

• Transaction applications
• Interactive applications
• Broadcast applications
• Multicast applications

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Transaction Applications

• Credit card authorization/transaction
• Package pickup, delivery, and tracking
• Fleet management
• POS
• Inventory control
• Emergency services

• M-ES/vehicle theft recovery
• Display of calling party name and number
• Notice of voice mail
• E-mail
• Information retrieval services
• Telemetry

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Examples of Telemetry

• Location service
• Vehicle statistics
• Mileage
• Speed
• Engine status
• Burglar or fire alarm reporting
• Vending machine status
• Weather statistics
• Traffic statistics
• Field measurements

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Examples of Information Retrieval

• Weather report for a particular place
• Traffic report for a specific area
• Directory assistance White pages
• Local service assistance Yellow pages
• Location and direction information
• Restaurant reservation service

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Interactive and Broadcast Apps.

• Interactive Remote access via direct network
  connection or via a packet assembly/disassembly
• Broadcast
• News
• Sports
• Weather
• Advertising

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Multicast Applications

• A subscription to obtain
• Market info.
• Business news
• News related to a specific area
• Classifieds for a particular area
• Recreational info.

• A subscription to a private bulletin to obtain
• Service bulletins
• Company functions
• Product info.
• Fraud warnings

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Data over Analog and Digital Cellular

• Data over analog cellular
• Data rate up to 14.4 Kbps
• Data over digital cellular
• Data rate
• Voice grade channel 9.6 Kbps
• GSM 270 Kbps
• Digital TDMA 30 Kbps

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Competing Mobile Data Services
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Paging and Two-Way Paging

• Paging steps
• Someone dialing the page number
• Central controller broadcasts the page to local
  controller
• Local controller broadcasts to base stations
• Base station broadcasts to end users

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One-Way Paging
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One-Way Paging
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Two-Way Paging

• Two kinds
• Two-way asymmetrical paging networks
• Two-way symmetrical paging networks
• Spectrum 900 MHz
• Bandwidth 50 MHz

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Asymmetrical Two-Way Paging

• Two separate networks
• One for outgoing traffic
• The other for incoming traffic
• Incoming networks receives more dense than the
  outgoing transmitters,
• e.g., a simple query may receive a much longer
  response

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Asymmetrical Two-Way Paging
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Comparison of Paging to Cellular

• Paging is inexpensive, ubiquitous, but with
  limited applications
• It may become very powerful when combined with a
  PDA because of its simplicity

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Comparison of Paging to Cellular
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Mobile Data Technologies
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Contents

• RAM/Mobitex network technologies
• Motorola ARDIS/Modacom network technologies
• CDPD network technologies
• Cell size classification

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RAM/Mobitex Network Technologies

• It offered by Ericsson in most parts of the
  world. In the US, it is jointly owned by RAM and
  Bell South
• The Network Control Center is the heart of the
  network
• Its protocol was developed by Ericsson and is open

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Parameters (in the US)

• Tx. Frequency 896-902 GHz
• Rx. Frequency 935-941 GHz
• 10-30 channel pairs in each metropolitan area
• Channel spacing 12.5 KHz

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Air Interface

• ROSI RadiO Signaling
• 0.3 GMSK Gaussian Minimum Shift Keying with
  BT0.3
• Block interleaving
• 16-bit CRC for error detection
• Reduced Hamming code for error correction
• Selective Automatic Repeat Request
• Channel access mechanism reservation slotted
  ALOHA
• Collisions are detected by the lack of ACK

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The Terminal Interface (DLC)

• MASC RAM/Mobitex Asynchronous Communications
• Handles data between the terminal and Mobidem
• Provides control and status monitoring of the
  Mobidem

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The Network Layer

• MPAK
• Max packet size of 512 bytes of info., plus
  header
• 24-bit addressing for the Mobitex number
• The transport layer protocol
• MTP/1

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Mobitex Packet
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Mobitex Protocol Layer
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Gateway Service

• Available via
• Mobitex directly Mobigate
• The third party
• Mobigate to hosts
• TCP/IP
• X.25
• SNA 3270
• Third party gateways to hosts
• SNA
• AS 400
• DECNet

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ARDIS/Modacom Network Technologies

• In most parts of world provided by Motorola
  called Modacom
• In US called ARDIS
• ARDIS separate company from IBM
• The network intelligence is concentrated in the
  hub
• Hub is connected to the Radio Frequency Network
  Control Points (RF NCP)
• InfoTAC the combination of radio and modem
• MAC protocol slotted ALOHA
• 25 KHz channel spacing

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The Terminal Interface

• MDC 4800, the original protocol
• 4.8 Kbps
• FSK
• RD LAP 19.2
• 19.2 Kbps
• Four level FSK
• RAM/Mobitex
• 8 Kbps
• GMSK

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The Terminal Interface (contd)

• The MDC 4800 protocol is quite robust
• Error detection and correction using 16 bits for
  32 bits of info.
• Employing convolutional code up 28 of error
  correction
• Bits are interleaved

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CDPD Network Technologies

• The basic idea was proposed by a scientist at
  IBM, Dr. Vic Moore

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The Services Provided by CDPD

• 19.2 Kbps
• Connectionless service
• Point-to-point
• Multicast
• Broadcast
• Security
• Authentication of users
• Authorization
• Encryption of data

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CDPD Reference Model
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Functions of the Air Link Network

• Overlays existing cell site equipment
• Accepts and forwards traffic to and from M-ESs
• Over the A-Interface
• At the PHY and MAC layers
• Manages channel allocation
• Two types of air link channels (IS-533)
• MDBS to M-Es forward/downlink
• M-Es to MDBS reverse/uplink
• Data stream is assigned a Channel Stream
  Identifier (CSI)

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Functions of MD-IS

• Uses and controls MDBSs
• Control mobile data link
• Manages mobility
• Does not perform complex routing decisions since
  they are included in the function of the ISs

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Air Link Network
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Functions of IS

• Perform network layer functions
• Route datagrams among F-ESs MD-ISs
• Support
• Internet protocol (IP)
• Connectionless network protocol (CLNP)
• Can be composed of several administrative domains
• Connection oriented communications are provided
  by transport layer in end system

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CDPD Switched Network
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Network Configuration
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CDPD Data Carriage Protocol

• MDLP Mobile Data Link Protocol
• SNDCP Sub Network Dependent Convergence Protocol

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Cell Size Classification