1. COMT 3911 Cellular and PCS Technical Issues COMT 391

2. 2 Overview Cell Layout Signaling Mobile Handset Operation

3. COMT 3913 System Block Diagram MobileBTSBSCMTSOPSTN Data Bases forward reverse BTSBase Tranceiver Station BSCBase Station Controller MTSOMobile Telephone Switching Office Radio LinkVoice Trunk Data Trunk

4. COMT 3914 Frequency Reuse Pattern

5. COMT 3915 Standards AMPS - United States TACS - UK NTT - Japan NMT - Scandanavia MATS-E - France C-450 - Germany GSM - global

6. COMT 3916 North American AMPS system 50MHz spectrum 30kHz per channel per direction 832 total full-duplex channels 4, 7, and 12 cell clusters used

7. COMT 3917 AMPS Specifics 832 channels (2 frequencies per channel) –Forward: 869-894 MHz –Reverse: 824-849MHz –Forward/Reverse Spacing: 45MHz –Adjacent Channel Spacing: 30kHz –21 Control Channels per group Cell Sizes: 2-20km

8. COMT 3918 Antenna Placement - high Good Coverage Co-Channel Interference Problems

9. COMT 3919 Buildings as Boundaries Cell Limits Defined Possible Adjacent Channel Interference

10. COMT 39110 Interference Co-Channel Interference Adjacent Channel Interference Outside Sources

11. COMT 39111 Signaling Channels Dedicated Control Channels (CC) –Mobile will scan for the strongest control channel when first switched on –System Identification –Number of Paging and Access Channels Paging Channels (PC) –Used to Initiate Calls to a Mobile Access Channels (AC) –Used to Initiate Calls from a Mobile

12. COMT 39112 Call Setup from Mobile Mobile receives AC number over PC User dialed digits are stored in the Mobile Mobile finds the strongest AC Mobile sends the dialed digits over the AC to the Base Station and the MTSO MTSO transmits the Voice Channel No.

13. COMT 39113 Call Setup From Mobile cont… Mobile tunes to the selected voice channel Mobile loops the supervisory audio tone (shows voice channel active) MTSO sends digits to the PSTN PSTN completes call

14. COMT 39114 Mobile-Originated Call MobileBTSBSCMTSOPSTN RCC MIN, ESN, dialed no validation FCC Ch No, SAT code, Power FVC SAT RVC SAT FVC RVC Conversation

15. COMT 39115 Call Setup to Mobile PSTN delivers call to MTSO MTSO transmits Mobile ID over all Paging Channels Mobile acknowledges on the strongest Access Channel MTSO selects the voice channel to use MTSO starts supervisory tone and sends voice channel number to mobile

16. COMT 39116 Setup to Mobile Cont. Mobile loops the supervisory tone MTSO instructs mobile to begin ringing Mobile rings and sends 10kHz alert tone to the MTSO Alert tone stops when mobile picks up, MTSO completes call connection

17. COMT 39117 Speech Channel Control Signals (AMPS) Signaling Tone (10kHz) from Mobile to MTSO –Alerting –Flash-hook, disconnect, etc. Supervisory Audio Tones (6kHz+/- 30Hz) (there are three of these) –Base Station to Mobile, looped back by the mobile

18. COMT 39118 Call Handoff Base Stations monitor the signal strength If strength drops below hand-off level, all base stations are asked to look for the mobile; strongest becomes new BS MTSO instructs the new base station to activate a voice channel to receive the handoff; BS starts transmitting the Supervisory Audio Tone.

19. COMT 39119 Call Handoff cont… Current base station at MTSO command sends signal to mobile giving the new channel assignment. Mobile send a signaling tone burst, and tunes to the new channel. Previous base station clears the call path.

20. COMT 39120 Mobile Handset ESN - Electronic Serial Number Programmable NAM (Number Assignment Module) Contains among other things –System ID –First control channel to scan –A/B system selection –MIN (Mobile Identification Number)

21. COMT 39121 Mobile Identification Number MIN1 - Mobile System Id (3 digits) –US: Area Code –International: Mobil Carrier Identifcation MIN2 - Station Number –US: NXX and line number –International: internal mobile number

22. COMT 39122 Hand-Off MTSO BS MS

23. COMT 39123 Roaming Mobile MTSO Mobile MTSO Mobile

24. COMT 39124 Intersystem Hand-Off MTSO BS MS MTSO

25. COMT 39125 The “Shoe-Lace” Effect BS MS

26. COMT 39126 Multi-System Tandem MTSO BS MS MTSO

27. COMT 39127 Automatic Roaming MTSO BS MS MTSO HLR VLR Request Response Billing Information Service Profile Current Location Temporary Directory Number

28. COMT 39128 The “Trombone” Effect MTSO BS MS MTSO Fixed Station

29. COMT 39129 Security/Fraud Issues Security –Privacy of Conversations –Denial of Service Fraud –Illegally obtained ESN/MINs –Roaming-related (“tumbling” ESNs)

30. COMT 39130 Classes of Standards Analog Cellular –FDMA - Frequency Division Multiple Access Digital Cellular –FDMA –TDMA - Time Division Multiple Access –CDMA - Code Division Multiple Access

31. COMT 39131 Access Methods Frequency Time Frequency Time Frequency Time FDMA TDMA CDMA

32. COMT 39132 Standards Content Frequency Bands Channel Assignments Voice Encoding Access Method and Frame Structure Signaling Structure