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Chapter 3

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  1. Chapter 3 Mobile Data Services and Technologies Prof. Huei-Wen Ferng

  2. Mobile Data Services Prof. Huei-Wen Ferng

  3. 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 Prof. Huei-Wen Ferng

  4. 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 ->19.2 Kbps (CDPD) • 9.6 Kbps in the other parts of the world Prof. Huei-Wen Ferng

  5. 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 Prof. Huei-Wen Ferng

  6. Australia Canada Finland Netherlands Norway Sweden UK US Rest of Europe (later) Latin America (later) The Pacific Rim (later) Countries that installed Mobitex networks Prof. Huei-Wen Ferng

  7. Hardware Radio Modem Terminal Application SW System integrators Software companies Network usage Mobitex Remark: the combination unit of radio and modem is called Mobidem What would you need to use the RAM/Mobitex network Prof. Huei-Wen Ferng

  8. 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 • >10 hours per battery charge • Support for nationwide roaming Prof. Huei-Wen Ferng

  9. 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 user’s 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 Prof. Huei-Wen Ferng

  10. Subscription Type for the Hosts • CCITT X.25 • ISO/HDLC • SNA 3270 • Mobitex asynchronous communications Prof. Huei-Wen Ferng

  11. 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 Prof. Huei-Wen Ferng

  12. Mobitex Partners • IBM • HP • Motorola • Intel • Fujitsu • Ericsson • AT&T Prof. Huei-Wen Ferng

  13. Developer and System Integrator Partners • DEC • Lotus • Novell • WordPerfect Prof. Huei-Wen Ferng

  14. The ARDIS/Modacom Mobile Data Service • Countries have installed Modacom • US • Germany • UK • Hong Kong • Data rate • US: 4.8 Kbps -> 19.2 Kbps (CDPD) • The other parts of the world: 9.6 Kbps Prof. Huei-Wen Ferng

  15. 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 Applications of Modacom Prof. Huei-Wen Ferng

  16. 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 InfoTAC Prof. Huei-Wen Ferng

  17. 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 Prof. Huei-Wen Ferng

  18. Four CDPD Applications • Transaction applications • Interactive applications • Broadcast applications • Multicast applications Prof. Huei-Wen Ferng

  19. 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 Transaction Applications Prof. Huei-Wen Ferng

  20. 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 Prof. Huei-Wen Ferng

  21. 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 Prof. Huei-Wen Ferng

  22. Interactive and Broadcast Apps. • Interactive: Remote access via direct network connection or via a packet assembly/disassembly • Broadcast • News • Sports • Weather • Advertising Prof. Huei-Wen Ferng

  23. 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 Multicast Applications Prof. Huei-Wen Ferng

  24. 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 Prof. Huei-Wen Ferng

  25. Competing Mobile Data Services Prof. Huei-Wen Ferng

  26. 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 Prof. Huei-Wen Ferng

  27. One-Way Paging Prof. Huei-Wen Ferng

  28. One-Way Paging Prof. Huei-Wen Ferng

  29. Two-Way Paging • Two kinds • Two-way asymmetrical paging networks • Two-way symmetrical paging networks • Spectrum: 900 MHz • Bandwidth: 50 MHz Prof. Huei-Wen Ferng

  30. 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 Prof. Huei-Wen Ferng

  31. Asymmetrical Two-Way Paging Prof. Huei-Wen Ferng

  32. 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 Prof. Huei-Wen Ferng

  33. Comparison of Paging to Cellular Prof. Huei-Wen Ferng

  34. Mobile Data Technologies Prof. Huei-Wen Ferng

  35. Contents • RAM/Mobitex network technologies • Motorola ARDIS/Modacom network technologies • CDPD network technologies • Cell size classification Prof. Huei-Wen Ferng

  36. 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 Prof. Huei-Wen Ferng

  37. 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 Prof. Huei-Wen Ferng

  38. Air Interface • ROSI: RadiO Signaling • 0.3 GMSK: Gaussian Minimum Shift Keying with BT=0.3 • 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 Prof. Huei-Wen Ferng

  39. The Terminal Interface (DLC) • MASC: RAM/Mobitex Asynchronous Communications • Handles data between the terminal and Mobidem • Provides control and status monitoring of the Mobidem Prof. Huei-Wen Ferng

  40. 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 Prof. Huei-Wen Ferng

  41. Mobitex Packet Prof. Huei-Wen Ferng

  42. Mobitex Protocol Layer Prof. Huei-Wen Ferng

  43. 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 Prof. Huei-Wen Ferng

  44. 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 Prof. Huei-Wen Ferng

  45. 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 Prof. Huei-Wen Ferng

  46. The Terminal Interface (cont’d) • 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 Prof. Huei-Wen Ferng

  47. CDPD Network Technologies • The basic idea was proposed by a scientist at IBM, Dr. Vic Moore Prof. Huei-Wen Ferng

  48. The Services Provided by CDPD • 19.2 Kbps • Connectionless service • Point-to-point • Multicast • Broadcast • Security • Authentication of users • Authorization • Encryption of data Prof. Huei-Wen Ferng

  49. CDPD Reference Model Prof. Huei-Wen Ferng

  50. 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) Prof. Huei-Wen Ferng