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TDC 461 Basic Communications Systems

Explore topics such as Computer Telephony Integration (CTI), Cordless & Cellular Telephones, Satellite Systems. Exam details and key concepts explained.

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TDC 461 Basic Communications Systems

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  1. TDC 461Basic Communications Systems Class #4 24 April, 2001

  2. Agenda • Computer Telephony Integration (CTI) • Cordless Telephones • Cellular Telephones • Satellite Systems

  3. Announcements: • Midterm exam next week • You can bring one 8.5”x11” sheet of Exam will be multiple choice, true false, fill-in-the-blank, and short answer. You will have to diagram a solution to at least one problem, so be prepared. • Exam will last until 7:30pm. • Review guide on the web.

  4. Computer Telephony Integration (CTI) • The concept: • Integrate PBX with computer services to • Integrate voice cabling with data cabling to save money

  5. Why CTI?

  6. PBX System Layout

  7. LAN System Layout

  8. Shared Cabling • Voice Network Layout and Data Network Layout looks the same!!

  9. Non-Integrated PBX & LAN

  10. Voice/Data Adjunct Services(with no PBX modifications) • Some voice/data convergence can be accomplished without PBX changes. • LAN servers can connect to PBX by standard voice trunks. • Examples

  11. Unified Messaging • Users utilize a single desktop application to receive and send • Voice mail can be recorded/heard through PBX telephone set or PC microphone/speaker.

  12. Unified Messaging

  13. FAX Server

  14. FAX Server

  15. CTI Configuration • First Party Control • Third Party Control

  16. CTI First-Party ControlIndividual connections to desktops

  17. CTI Third-Party ControlConnect through CT Server

  18. CTI Third-Party ControlAlternative: Direct LAN Connection to PBX

  19. CTI Applications • Intelligent Call Assignment for ACD • Data lookups triggered by calling number (ANI / DNIS) • Linking database records and PBX call records • Intelligent Voice Response Unit / Faxback • Control voice calls via PC applications

  20. CTI Software Configuration • CTI Software required on: • All CTI functions and messaging defined by CTI Applications Programming Interface (API)

  21. CTI APIs • Telephony Services API (TSAPI) • Telephony API (TAPI) • CallPath • Java Telephony API (JTAPI)

  22. CTI Summary • Advantages • Disadvantages • .

  23. Cordless Telephones

  24. Cordless Telephones • Base unit=> • Portable unit=> • Signaling carried between base and portable using out-of-band frequencies.

  25. Cellular Technologies Cell 3 Cell 2 Cell 1

  26. Previous Wireless SystemsSingle Powerful Transmitter

  27. Wireless Before CellularProblem: Limited Capacity • Before 1981: • FDM • Limited number of users: • Very limited capacity

  28. Cellular Services • 728 Mobile Service Areas (MSAs) defined by the FCC in the United States. • 2 Cellular carriers in each MSA • A Carrier : • B Carrier :

  29. Cellular Concept:Many Low Power Base Stations Cell 3 Cell 2 Cell 1

  30. Cellular increases capacity using Frequency Reuse • 7-way Frequency Reuse: Chan 41-80 Chan 201-240 Chan 1-40 Chan 161-200 Chan 41-80 Chan 121-160 Chan 1-40 Chan 81-120 Chan 241-280 Chan 121-160 Chan 201-240 Chan 81-120

  31. Mobile Telephone Switching Office (MTSO) • Interconnection=> • Switching=>. • Interconnection with wireline=> MTSO Mobile Office Trunks Central Office

  32. Cellular Network Signaling • Registration • Call Handoff • Roaming

  33. Call Handoff • Caller moves from one cell to another:

  34. Cellular Systems • Advanced Mobile Phone System (AMPS) • IS-54B Digital Cellular (TDMA)

  35. Personal Communications Systems (PCS) • Combines voice and data services • Intelligent network • Code Division Multiple Access (CDMA)

  36. Personal Communications Systems (PCS) • Smart PCS equipment=>

  37. How to Share Airwaves? • Frequency Division Multiple Access (FDMA)

  38. How to Share Airwaves? • Time Division Multiple Access (TDMA) • Example: For 3 voice channels, • Voice Channel 1: data bytes #1, #4, #7, #10, … • Voice Channel 2: data bytes #2, #5, #8, #11, … • Voice Channel 3: data bytes #3, #6, #9, #12, ...

  39. How to Share Airwaves? • Code Division Multiple Access (CDMA) • Example: • Voice channel 1: ‘0’ = 0101100, ‘1’ = 1010011 • Voice channel 2: ‘0’ = 1100110, ‘1’ = 0011001

  40. How to Share Airwaves? • Advantages: • FDMA: • TDMA: • CDMA:

  41. Satellite Systems

  42. Satellite Systems • Satellites are big repeaters in the sky

  43. Advantages to Satellites • Coverage • Geosynchronous satellite=> • Distance Insensitivity • Scalability

  44. Disadvantages to Satellites • Propagation Delay • Weather

  45. Satellite Orbits • Geosynchronous Earth Orbit (GEO) • Orbits 22,300 miles above earth • Appears to be motionless from Earth • Uses: TV, telephony, intelligence • Low Earth Orbit (LEO) • Orbits 100-1000 miles above earth • Satellite rises and sets in ~15 minutes when viewed from Earth • Advantage: Much smaller propagation delay • Uses: New voice/data networks

  46. Example: Iridium • Iridium is LEO network • Built by consortium lead by Motorola • Constellation of 66 LEO satellites • 11 satellites in each of 6 different polar orbits • Provides voice communications from anyplace to anyplace on Earth. • 12 Gateways provide interconnection to international public telephone networks • Commercial service started in Nov. 1998

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