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Topics Covered

Cellular Telephone Service. Topics Covered. Service Definition Service Architecture Overview Cell Sites Mobile Telephone Switching Office Transmission Channels Voice Channels. Cellular Technologies. Advanced Mobile Phone Service (AMPS)

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Topics Covered

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  1. Cellular Telephone Service Topics Covered • Service Definition • Service Architecture Overview • Cell Sites • Mobile Telephone Switching Office • Transmission Channels • Voice Channels

  2. Cellular Technologies • Advanced Mobile Phone Service (AMPS) • Amps Was The First North American Cellular System. • Operates In The 800-MHz Region (824 To 849 MHz, And • 869 To 894 MHz). • AMPS Employs A Channel Bandwidth Of 30 kHz. • Later Versions Of AMPS (AMPS/IS-41) Incorporate • Transparent Roaming Techniques Adapted From GSM • (See The Next Slide).

  3. Cellular Technologies - Continued • Global System For Mobile Communication (GSM) • A Pan-European System, GSM Is A Second-Generation • Digital, Cellular, Land Mobile Telephone System.. • Operates In The 900-MHz Region (890 To 915 MHz, And • 935 To 960 MHz). • GSM-900 Employs 200 kHz Channels Separated By 45 MHz. • Each Channel Is Time-Divided To Create Eight Subchannels • (FD/TDMA).

  4. Cellular Technologies - Continued • Global System For Mobile Communication (GSM) • GSM-1800 And GSM-1900 Employ The Same Technology • And Operate In The PCS Bands (Personal • Communications Service Around 1.8 GHz In Europe And 1.9 • GHz In North America). • GSM Pioneered Automatic Roaming Techniques, Mobile- • Assisted Handover, Subscriber Authentication, And User • Privacy.

  5. Cellular Technologies - Continued • Digital AMPS (D-AMPS And NA-TDMA) • D-AMPS, Defined By Telecommunications Industries • Association Interim Standard 54. • D-AMPS Employs AMPS Frequencies. • It Provides Three Digital Channels (TDMA) In A 30-kHz • Channel, And Employs A Combination Of Analog And • Digital Control Channels. • Dual-Mode Terminals Operate With AMPS Or D-AMPS To • Facilitate The Evolution Of AMPS To A Higher-Capacity • Digital System.

  6. Cellular Technologies - Continued • Digital AMPS (D-AMPS And NA-TDMA) • NA-TDMA Is Defined By Telecommunications Industries • Association Interim Standard 136. • NA-TDMA Operates In Two Frequency Bands. • At AMPS Frequencies, It Provides Six Digital Channels In A • 30-kHz Channel, And Employs A Combination Of Analog • And Digital Control Channels. • Dual-Mode Terminals Operate In Analog Or Digital Modes. • At PCS Frequencies (Around 1.9 GHz), NA-TDMA Provides • Six Digital Channels In A 30-kHz Channel, And Uses Digital • Control Channels Exclusively.

  7. Cellular Technologies - Continued • Digital AMPS (D-AMPS And NA-TDMA) • In The Digital Mode, Automatic Roaming, Mobile-Assisted • Handoff, Terminal Authentication, And User Privacy Are • Provided. • DQPSK (Differential Quaternary Phase-Shift Keying) Is • Employed.

  8. Cellular Communications Cellular Telephony Provides Communications Services To Hand-Held Portable Phones And Interconnects With The Public Telephone Network By Using Radio Transmissions That Are Based On A System Of Cells And Antennas.

  9. Cellular • A Wireless Design Method Where Multiple • Transmitters Are Strategically Placed • Throughout A Geographical Area To Provide • Two Functions. • To Radiate The Area With An Adequate • Signal. • To Make The Size Of The Radiated Area • Adequate To Accommodate The Number • Of Users.

  10. Cell Layout – Antenna Location - Cell Site Antenna - “Fade” Area Cell Cell Cell Cell • Cellular Telephony Is Provided By A Series Of Directional • Antennae Providing Area Coverage In The Form Of • Hexagonal Cells.

  11. Cell Coverage • Closely-Spaced Hexagons Provide More • Efficient Area Coverage Than Would • Closely-Spaced Circles. • Directional Antennae Are Used To • Radiated The Coverage Area.

  12. Cellular Components Hut/ ”Doghouse” Antenna MTSO AC SMS HLR VLR MTSO AC SMS Class 5 Switch HLR • The Transmit And Receive Center For The • Geographical Area Called A Cell. VLR

  13. Sample Cellular Antennae

  14. Cellular Components • Each Cell Site Contains: • Transmitter • 2 Receivers Per Cell • Cell Site Controller • An Antenna • Voice/Data Land Links To The MTSO • Loops From MTSO To Class 5 CO

  15. Cell Site Antenna Hut/ ”Doghouse” • The Transmit And Receive Center For The • Geographical Area Called A Cell. • The Cell Shape Is Roughly Hexagonal.

  16. Cell Site • The Cell Consists Of An Antenna, A Hut And A • “Doghouse”. • “Doghouse” Contains The Transmitting And • Receiving Electronics.

  17. A Sectored Cell • Each Cell Consists Of As Many As 128 Channels Per • Cell. • “Doghouse” Contains The Transmitting And • Receiving Electronics. • Two To Six Sectors. • A Maximum Of 128 Channels Per Cell & 70 • Channels Per Cell On Average.

  18. A Sectored Cell • A Minimum Of One Control Channel Is Provided, • Dedicated Control Channel (DCCH), To Control The • Mobiles.

  19. Cell Sites • Cell Boundaries Are Neither Uniform Nor Constant. • Usage Density • Landscape

  20. Cellular Service Architecture • Dedicated Control Channel (DCCH) • Voice Channel MTSO AC SMS Handset HLR VLR Class 5 Switch

  21. Cellular Telephone Handset • Provides The Interface Between The User And The Cellular System. • Dial-First - Each Cellular System Can Support Only A Limited Number Of Talk Paths At A Time. • Dial Tone Received After The SEND Button Is Pressed.

  22. Cellular Telephone Handset Identification Codes • Each Mobile Is Assigned Four Permanent Identification Codes.

  23. Cellular Telephone Handset Identification Codes • Mobile Identification Number (MIN) – A 10-Digit Directory Number Assigned To Each Mobile Subscriber. It Is Stored As A 34-Bit Code That Consists Of: - Area Code – Three Digits That Identify The Mobile Telephone’s Home Service Area. - Exchange Code – Three Digits That Identifies The Mobile Telephone Service Office (MTSO) Of The Home Service Provider Within The Given Area Code. - Subscriber Number – Four Digits That Identify The Mobile Scriber.

  24. Cellular Telephone Handset Identification Codes • Electronic Serial Number (ESN) – A 32-Bit Code Assigned To The Mobile Station Equipment By The Manufacturer. • ESN Is A Unique Identification Number Embedded In A Wireless Phone By The Manufacturer. • Each Time A Call Is Placed, The ESN Is Automatically Transmitted To The Base Station So The Wireless Carrier's Mobile Switching Office Can Check The Call's Validity.

  25. Cellular Telephone Handset Identification Codes • Station Class Mark (SCM) – A 4-Bit Code That Describes The Capabilities Of The Mobile Station, Including. • Bit 1 Tells The Cell Tower Whether Your Cell Phone Uses The Older 666 Channel Cellular System Or The Newer 832 Channel Cellular System. • Bit 2 Tells The System Whether Your Cellular Telephone Is A Mobile Unit Or A Voice Activated Cellular Telephone.

  26. Cellular Telephone Handset Identification Codes • Station Class Mark (SCM) – Continued. • Bits 3 And 4 Tell The Cell Tower What Power Your Cellular Phone Should be Using.

  27. Cellular Telephone Handset Identification Codes • System Identifier (SID) – A 15-Bit Code Assigned By By The FCC That Identifies Cellular Geographic Service Area In Which The Service Provider Is Licensed . • It Is Used To Determine If A Mobile System Is Operating In Its Home Area. • If The SID Stored In The Mobile Telephone And The Serving Cell Do Not Match, The Mobile Is Roaming.

  28. Cellular Telephone Handset Logic/Control • Numeric Assignment Module (NAM) – Used For Programmable Assignment Of Unit’s Telephone Number. • Electronic Serial Number (ESN) – Unique Fixed Number For Each Unit. • Carrier Records Both Numbers In The HLR At The Time Service Is Setup.

  29. Cellular Service Architecture Class 5 Switch MTSO HLR VLR • MTSOs Track Mobiles • That Are (1) • Operating In Their • Home Area, And (2) • Roamers.

  30. Cellular Telephone Communications Channels • Two Types Of Channels Are Provided – • Setup/Data Channels – Transmits Data Used To Set UpAll Calls. • Voice Channels – Provides Message Paths And Carries Signals Needed For Call Supervision – i.e., To Signal Changes In State And To Maintain The Connection..

  31. Cellular Telephone Communications Channels - Continued - • The Supervisory Signals Are: • Supervisory Audio Tone (SAT) – An Out-Of -Band, Continuous Tone (5,700, 6,000 Or 6,300 Hz), The SAT Is Present Whenever A Call Is In Progress. • Absence Of The SAT Tone Indicates That One Of The Parties Has Gone On-Hook. • Nearby Cells Are Assigned Different SATs To Assist In Distinguishing Between Signals.

  32. Cellular Telephone Communications Channels - Continued - • The Supervisory Signals Are: • Signaling Tone (ST) – An Out-Of-Band Tone Burst (10 kHz). • Among Other Things, The Signaling Tone Is Used To Initiate Ringing, To Signal Hand Off To Another Cell Site, And To Disconnect.

  33. Cellular Handset Registration MTSO AC SMS Handset HLR VLR • Over-The-Air Registration Carried Out Each Time • The Mobile Unit Is Turned On. • Registration Required Before Call Can Be Made.

  34. Cellular Handset Registration MTSO AC SMS Handset HLR VLR • Over-The-Air Registration Uses The Data Control • Channel – Not The Voice Channel. • Mobile Unit Passes Its Telephone Number Stored • In Its NAM And Its ESN To The MTSO. • MTSO Uses The DBs To Verify Mobile’s Authenticity.

  35. Cellular Handset Registration • The Base Station & Mobile Unit Uses The Control • Channel To Support Incoming And Outgoing Calls. • Used To Monitor Signal Quality. • Used To Register. • Used Only When The Station Is “Off-The-Hook”. • For Incoming Calls, The System Uses The • Control Channel To Alert The Station Of A Call.

  36. Cellular Location Registers MTSO HLR VLR • Home Location Register – Contains Customer-Based • Information (NAM, ESN, Etc.) For Customers • Whose Telephone Numbers Belong To The Carrier • And That Are Located Within The Area Code. • Visitor Location Register - Contains Customer-Based • Information (NAM, ESN, Etc.) For Roaming Customers. • Registration Supported By Both HLR & VLR.

  37. Registration Non-Roaming DCCH MTSO NAM-Based Tel. No. & ESN HLR • MTSO Verifies Handset Authenticity Using HLR. • Once Registration Is Complete, Service Is Allowed.

  38. Home Location Register HLR • Home Location Register (HLR) Is The Main • Database Of Permanent Subscriber Information For • A Mobile Network. • HLR Contains Pertinent User Information, Including • Telephone Number, ESN, Address, Account Status, • And Preferences.

  39. Registration Roaming – Case 1 DCCH MTSO NAM-Based Tel. No. & ESN VLR • A Customer Record Exists At The VLR. • Unit Is Registered Using VLR-Located Customer • Record.

  40. Registration Roaming – Case 2 DCCH MTSO NAM-Based Tel. No. & ESN VLR Class 5 Switch • No Customer Record Exists At The VLR. • MTSO Communicates With Home-System And • Registers The Unit In The VLR.

  41. Visitor Location Register VLR • If The User Is Out Of The Home Area, The Area • VLR Sends Out A Request For Information • Required To Process The Call. • User Information Passed From The Home HLR • Includes Telephone Number, ESN, Address, Account • Status, And Some Preferences.

  42. Cellular Signal Strength Cell Site 2 Freq. Group 2 Cell Site 1 Freq. Group 1 Cell Site 4 Freq. Group 4 MTSO Cell Site 3 Freq. Group 3 Handset Cell Site 5 Freq. Group 5 • A Mobile Unit’s Signal May Be Received By More • Than One Cell Site At A Time.

  43. Cellular Signal Strength MTSO Handset • Signal May Be Received By More Than One Cell • Site At A Time. • MTSO Compares Signal Strengths And Specifies • Which Cell Site To Use.

  44. Cellular Handoff MTSO Handset • As Mobile Unit Moves Around Coverage Area, • The MTSO Changes The Antenna Used. • The MTSO Uses The SAT Signal Strength To • To Determine Whether, And How To Switch • The Call To Another Antenna. • Handoff Requires About 0.2 Seconds.

  45. Roaming • The Ability For Cellular Phone Users To Make Or Receive Calls On Other Service Providers‘ Networks When Outside The Coverage Area Of Their Own Cellular Network Service Provider • Visitor Location Register.

  46. Short Message Service • Short Message Service (SMS) Applications • Include Two-Way Point-To-Point Messaging. • SMS Is Also Used For Paging. • Supports Alphanumeric Messages.

  47. Authentication Center • Because Radio Signals Can Be Accessed By • Virtually Anyone. • Authentication Involves Two Functional • Entities. • SIM • The Authentication Center • The SIM And AC Contain A Secret Key And • They Pass Randon Numbers Between Them.

  48. Some Cellular Standards • EIA/TIA 95B – Digital Over-The Air Standard. • EIA/TIA 136 (Supports DCCH).

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