1. MOBILE COMMUNICATION

2. PSTN TRANSFER MODE : CIRCUIT SWITCHING
NETWORK TYPE : DIGITAL EXCEPT PART OF ACCESS NETWORK
CHANNEL CAPACITY : 64 KBPS

3. CELLULAR SYSTEM

4. CELLULAR MOBILE SYSTEM
A WIRELESS MOBILE COMMUNICATION NETWORK ENABLES USERS TO INITIATE AND RECEIVE PHONE CALLS USING MOBILE PHONES
CELLULAR MOBILE TELEPHONY IS DIFFERENT FROM THE LANDLINE TELEPHONY IN THAT THE MOBILE SUBSCRIBER CAN INITIATE AND RECEIVE CALLS WHILE ON MOVE WITHOUT ANY DISRUPTION IN THE CALL
CELLULAR TELEPHONY DERIVES ITS NAME FROM THE PARTITION OF A GEOGRAPHIC AREA INTO SMALL PARTS CALLED “CELLS”

5. CELLULAR MOBILE SYSTEM (CONTD.)
EACH CELL IS COVERED BY A LOCAL TRANSMITTER AND RECEIVER POWERFUL ENOUGH TO ENABLE CONNECTIVITY WITH CELLULAR PHONES (MOBILE STATIONS / MOBILE TERMINALS / MOBILE EQUIPMENT) WITHIN ITS AREA
A SEPARATE RADIO FREQUENCY IS USED FOR EACH DIRECTION OF COMMUNICATION
MOBILE PHONE TO CELL SITE : UPLINK TRANSMISSION
CELL SITE TO MOBILE PHONE : DOWNLINK TRANSMISSION
THE SPECTRUM OF RADIO FREQUENCIES AVAILABLE FOR COMMUNICATION IS LIMITED AND ARE ALLOCATED TO DIFFERENT CELLULAR TECHNOLOGIES

6. RADIO FREQUENCY ALLOCATION TO MOBILE COMMUNICATION

7. CELLS
ANTENNA
TOWER
CELLS

8. CELLS
CELLS ARE SMALL SECTIONS OF AN AREA WITH ANTENNA, TRANSMITTER AND RECEIVER
CELLS ARE DEFINED BY ITS
PHYSICAL SIZE
SIZE OF POPULATION
CELL RADII CAN VARY FROM HUNDREDS OF METERS IN CITIES TO TENS OF KILOMETERS IN COUNTRY SIDE
CELLS ARE REPRESENTED BY HEXAGON WITH HONEYCOMB PATTERN

9. TYPES OF CELLS MACRO CELL MICRO CELL PICO CELL SELECTIVE CELL
LARGE CELL WITH DIAMETER >= 10 KM
TRANSMITTER POWER 1 TO 6 W
MICRO CELL
SMALL CELL WITH DIAMETER OF UPTO 1 KM
TRANSMITTER POWER 01 TO 1 W
PICO CELL
VERY VERY SMALL CELL
USED FOR INDOOR TRANSMISSION IN BUILDINGS OR TUNNELS
SELECTIVE CELL
COVERAGE LESS THAN 360 DEGREES
USED TO FILL GAPS IN THE COVERAGE
UMBRELLA CELL
USED IN MICRO CELL BUT WITH DIFFERENT CHANNEL FOR TRANSMISSION
USAGE EXAMPLE : AT PLACES WHERE HEAVILY USED ROAD CROSSES THE MICRO CELL AREA
THE FIRST THREE TYPES ARE BASED ON SIZE OF CELL
THE LAST TWO TYPES ARE BASED ON SPECIAL FUNCTIONS

10. EVOLUTION OF MOBILE COMMUNICATION
1940 : MTS ( MOBILE TELEPHONE SYSTEM )
MTS USED FREQUENCY MODULATION TECHNIQUE
IT USED SINGLE CARRIER FREQUENCY IN THE RABGE OF 35 TO 45 MHz
HALF DUPLEX OPERATION
ALL CALLS HANDLED THROUGH OPERATOR
MOBILES PHONES HAD PUSH-TO-TALK SWITCH
5 DIGIT MOBILE NUMBER
NO CONNECTIVITY WITH PSTN – MOBILE TO PSTN AND VICE VERSA NOT POSSIBLE
1964 : IMTS ( IMPROVED MTS )
SEVERAL CARRIER FREQUENCIES USED TO HAVE SIMULTANEOUS CALLS
NEED FOR OPERATOR WAS ELEMINATED
WIDE AREA COVERAGE
BASE STATION TRANSMITTER POWER 100 TO 200 W
MOBILE PHONE TRANSMITTER POWER 5 TO 25 W
MOBILE PHONE NUMBERS OF SAME LENGTH AS PSTN NUMBERS. SO MOBILE TO PSTN AND VICE VERSA CLLS WERE POSSIBLE

11. EVOLUTION OF CELLULAR NETWORK

12. EVOLUTION OF CELLULAR NETWORK
NMT
NORDIC MOBILE TELEPHONE ( 450 & 900 MHz )
AMPS
ADVANCED MOBILE PHONE SYSTEM ( 850 MHz )
DAMPS
DIGITAL AMPS
CDMA
CODE DIVISION MULTIPLE ACCESS SYSTEM
GSM
GLOBAL SYSTEM FOR MOBILE COMMUNICATION ( TDMA 900 MHz EUROPE)
DCS
DIGITAL CELLULAR SYSTEM ( TDMA GSM EUROPE )
PCS
PERSONAL CELLULAR SYSTEM ( TDMA GSM 1900 US )
UMTS
UNIVERSAL MOBILE TELECOM SYSTEM
IMT
INTERNATIONAL MOBILE SYSTEMS

13. CELLULAR TELEPHONY SERVICES
CELLULAR TELEPHONY HAS EVOLVED FROM BEING JUST A VOICE SERVICE TO PROVIDING A RICH COLLECTION OF VOICE, DATA AND MULTIMEDIA SERVICES
KEY CELLULAR SERVICES :
TEXT MESSAGING (SMS)
INSTANT MESSAGING (CHAT)
MULTIMEDIA MESSAGING (MMS)
EMERGENCY CALLS
WIRELESS INTERNET
VIDEO-ON-DEMAND
MOBILE TV
IP BASED MULTIMEDIA COMMUNICATION

14. COMPARISON OF CELLULAR SYSTEMS
PARAMETER
AMPS
TACS
NMT450
NMT900
FREQUENCY BAND (MHz)
800
900
450
CHANNEL SPACING (KHz) 30 25
12.5
SPEECH MODULATION FM
SIGNALLING
FSK
BIT RATE
10 KBPS
8 KBPS
1200 BPS

15. MEDIUM ACCESS CONTROL
CHANNELIZATION IS A MULTIPLE ACCESS METHOD IN WHICH THE AVAILABLE BANDWIDTH OF A LINK IS SHARED IN TIME, FREQUENCY OR USING CODE BY NUMBER OF STATIONS
THE MEDIUM ACCESS CONTROL TECHNIQUES ARE :
FDMA ( FREQUENCY DIVISION MULTIPLE ACCESS )
TDMA ( TIME DIVISION MULTIPLE ACCESS )
CDMA ( CODE DIVISION MULTIPLE ACCESS )

16. FDMA FREQUENCY DIVISION MULTIPLE ACCESS
THE BANDWIDTH IS DIVIDED INTO SEPARATE GREQUENCY BANDS

17. TDMA TIME DIVISION MULTIPLE ACCESS
THE BANDWIDTH IS DIVIDED INTO TIME SLOTS

18. CDMA CODE DIVISION MULTIPLE ACCESS
DATA FROM ALL STATIONS ARE TRANSMITTED SIMULTANEOUSLY AND ARE SEPARATED BASED ON CODING THEORY

19. COMPONENTS OF CELLULAR NETWORK
BASE TRANCEIVER STATION ( BTS )
BASE STATION CONTROLLER ( BSC )
MOBILE SWITCHING CENTRE (MSC )
OR MOBILE TELEPHONE SWITCHING OFFICE (MTSO)
LOCATION REGISTERS ( HLR & VLR )
AUTHENTICATION CENTRE ( AuC )
LINKS TO PSTN

20. BASE TRANVEIVER STATION (BTS)
BTS CONSISTS OF
ELECTRONIC SECTION LOCATED AT THE BASE OF ANTENNA TOWER AND INCLUDES
FREQUENCY AMPLIFIER
RADIO TRANCEIVER
RADIO FREQUENCY COMBINER
CONTROL LINKS
COMMUNICATION LINKS TO BSC
POWER SUPPLY WITH BACKUP
ANTENNA AND FEEDER SECTION
INTERFACE BETWEEN BTS AND BSC
CONTROL LOGIC
SOFTWARE

21. BTS
BTS LOCATION IN THE CELL, HEIGHT OF ANTENNA AND ORIENTATION ARE ALL IMPORTANT FACTORS TO ENSURE REQUIRED COVERAGE IN THE CELL
DIFFERENT LOCATIONS OF BTS ARE :
CENTRE EXCITED CELL
CORNER EXCITED CELL
EDGE EXCITED CELL
OMNI DIRECTIONAL ANTENNA
SECTORED DIRECTIONAL ANTENNA

22. MOBILE SWITCHING CENTRE (MSC)
MSC CONTROLS BSCs
ACTS AS SWITCH AND CONNECTION TO PSTN
ACTS AS AN AUTHENTICATION CENTRE (AuC)
CONTAINS REGISTERS – THE DATABASES MAINTAINING MOBILE LOCATION INFO
CONTROLS CHANNEL ASSIGNMENT, CALL PROCESSING, CALL SETUP AND TERMINATION, SIGNALLING, SWITCHING AND SUPERVISION
CONTAINS FACILITIES TO GENERATE BILLING INFO FOR CUSTOMER ACCOUNTS
IN VIEW OF ITS IMPORTANCE, MANY BACKUP AND DUPLICATE CIRCUITS ARE PROVIDED TO ENSURE THAT THER ARE NO FAILURES

23. AUTHENTICATION CENTRE (AuC)
USER’S IDENTITY IS CHECKED TO PROVIDE AUTHENTICATION AND ENCRYPTION PARAMETERS
AuC MAINTAINS A REGISTRATION DATABASE OF USERS ALLOWED TO USE THE NETWORK
AuC FUNCTION IS NECESSARY FOR SECURITY AS WELL AS BILLING OPERATION

24. EQUIPMENT IDENTITY REGISTER (EIR)
EIR IS A DATABASE HOLDING DETAILS OF MOBILE PHONE EQUIPMENT IN THE FORM OF IMEI NUMBER
IMEI ( INTERNATIONAL MOBILE EQUIPMENT IDENTITY ) NUMBER CAN BE ACCESSED AS FOLLOWS :
BY ENTERING *#06# ON MOBILE
ALSO PRINTED INSIDE THE PHONE
EIR DATABASE IS USED TO PREVENT CALLS FROM STOLEN, UNAUTHORIZED MOBILE PHONES
THE NETWORK OPERATORS MAINTAIN 3 SEPARATE LISTS OF IMEI IN THE EIR
GREY : MOBILE PHONES TO BE TRACKED
BLACK : BARRED MOBILE PHONES
WHITE : VALID MOBILE PHONES

25. LOCATION REGISTERS ( HLR, VLR)
HLR : HOME LOCATION REGISTER
CONTAINS SEMI-PERMANENT INFORMATION OF SUBSCRIBERS
KEEPS USER PROFILE OF USERS REGISTERED WITH THE NETWORK
MSC REFERS TO THE SUBSCRIBER INFORMATION IN THE HLR
THE HLR DATA OF A SUBSCRIBER IS STORED AS LONG AS THE SUBSCRIBER REMAINS WITH MOBILE OPERATOR
HLR ALSO STORES CURRENT LOCATION OF THE SUBSCRIBER AND SERVICES TO WHICH HE/SHE HAS ACCESS

26. LOCATION REGISTERS ( HLR, VLR)
VLR : VISITOR LOCATION REGISTER
CONTAINS TEMPORARY INFORMATION ABOUT THE MOBILE SUBSCRIBERS CURRENTLY LOCATED IN THE SERVICE AREA OF AN MSC BUT WHOSE HLR ARE ELSEWHERE
ROAMING USER RECORD IS ADDED TO VLR WHENEVER AN MSC DETECTS A NEW MOBILE PHONE IN ITS AREA
THE MSC CONTACTS THE HLR OF THE MOBILE SUBSCRIBER’S HOME LOCATION AND GETS THE DETAILS REQUIRED TO VALIDATE THE USER

27. CONNECTING TO NETWORK
WHEN A MOBILE PHONE IS SWITCHED ‘ON’, IT NEEDS TO COMMUNICATE WITH THE CELLULAR NETWORK TO REGISTER
THE MOBILE PHONE USES A ‘PAGING’ OR ‘CONTROL’ CHANNEL TO MAKE THE CONTACT WITH THE BASE STATION AND SENDS ‘ATTACH’ REQUEST
THE AUTHENTICATION CENTRE VERIFIES THE USER’S IDENTITY
ONCE VALIDATED, THE HOME LOCATION REGISTER (HLR) AND THE VISITOR LOCATION REGISTER (VLR) ARE UPDATED
PERIODICALLY, EVEN IF THE MOBILE PHONE IS IDLE, THE MOBILE PHONE COMMUNICATES WITH THE BASE STATION TO UPDATE ITS STATUS AND LOCATION
WHEN MOBILE PHONE IS SWITCHED ‘OFF’, IT SENDS A ‘DETACH’ REQUEST TO THE BASE STATION
THE NETWORK THEN UPDATES THE LAST KNOWN LOCATION OF THE MOBILE IN THE DATABASE

28. CLUSTER CLUSTER IS A GROUP OF CELLS
THE CELLULAR NETWORK AREA IS DIVIDED INTO NUMBER OF CELLS
THESE CELLS ARE GROUPED INTO NUMBER OF CLUSTERS
FOR HEXAGONAL CELLS, POSSIBLE CLUSTER SIZES ARE GIVEN BY THE FORMULA :
c = i^2 + I x j + j^2
Where ‘c’ is cluster size and ‘i’ and ‘j’ are non-negative numbers
FOR EXAMPLE, i = 2 & j = 1 GIVES CLUSTER SIZE OF 7 CELLS

29. CLUSTER (CONTD.)
THE INTEGERS ‘i’ & ‘j’ DETERMINE THE RELATIVE LOCATIONS OF CO-CHANNEL CELLS
CO-CHANNEL CELLS CAN USE THE SAME FREQUENCIES
IN THE DIAGRAM, CELLS WITH THE SAME LABEL ARE “CO-CHANNEL CELLS”
TO LOCATE A CO-CHANNEL CELL, MOVE ‘i’ CELLS, TURN 60 DEGREES COUNTER CLOCKWISE, MOVE ‘j’ CELLS IN THAT DIRECTION

30. LOCATING A CO-CHANNEL CELL

31. CELL PATTERN : CLUSTER OF 3 CELLS

32. CELL PATTERN : CLUSTER OF 7 CELLS

33. NO. OF CHANNELS IN A CLUSTER
NO. OF CHANNELS IN A CLUSTER IS GIVEN BY THE FORMULA :
F = G x N
WHERE,
F : NO. OF FULL DUPLEX CHANNELS AVAILABLE IN A CLUSTER
G : NO. OF CHANNELS IN A CELL
N : NO. OF CELLS IN A CLUSTER

34. TOTAL CHANNEL CAPACITY OF AN AREA
TOTAL CHANNEL CAPACITY OF AN AREA IS GIVEN BY THE FORMULA :
C = m x G x N
= m x F
WHERE,
C : TOTAL CHANNEL CAPACITY OF THE AREA
M : NO. OF CLUSTERS IN THE AREA
G : NO. OF CHANNELS IN A CELL
N : NO. OF CELLS IN A CLUSTER
F : NO. OF CHANNELS IN A CLUSTER

35. CHANNEL CAPACITY
THUS, THE CHANNEL CAPACITY OF CELLULAR NETWORK IS DIRECTLY PROPORTIONAL TO THE NO. OF CLUSTERS IN THAT NETWORK
‘N’ IS CALLED THE CLUSTER SIZE AND IS TYPICALLY 3, 7, OR 12 CELLS PER CLUSTER

36. FREQUENCY REUSE
FREQUENCY REUSE IS THE PROCESS IN WHICH THE SAME SET OF FREQUENCIES ( CHANNELS ) CAN BE ALLOCATED TO MORE THAN ONE CELL
FREQUENCY REUSE HAS BECOME ESSENTIAL DUE TO
LIMITED FREQUENCY SPECTRUM AVAILABLE FOR CELLULAR MOBILE COMMUNICATION
TREMENDOUS GROWTH IN THE NUMBER OF MOBILE USERS
IT IS POSSIBLE TO REUSE A FREQUENCY OUTSIDE THE RANGE OF THE RADIO TRANSMITTER
CELLS IN A CLUSTER USE UNIQUE FREQUENCY CHANNELS. HOWEVER, DIFFERENT CLUSTERS CAN USE THE SAME SET OF FREQUENCIES

37. FREQUENCY REUSE FACTOR ( FRF )
THE FREQUENCY REUSE FACTOR IS GIVEN BY THE EQUATION :
FRF = N / C
WHERE,
FRF : FREQUENCY REUSE FACTOR
N : TOTAL NO. OF CHANNELS IN AN AREA
C: TOTAL NO. OF CHANNELS IN A CELL

38. REUSE DISTANCE REUSE DISTANCE ‘D’ = ( ) X R
WHERE, R : CELL SIDE, AND N: CLUSTER SIZE
THE REUSE FACTOR ‘q’ = D/R OR = 3N

39. ADJACENT CHANNEL INTERFERENCE
INTERFERENCE CAUSED BY TRANSMISSION OF ADJACENT FREQUENCIES
GENERALLY THE FREQUENCY CHANNELS USED ARE SEPARATED BY 200 KHz SO AS NOT TO INTERFERE WITH EACH OTHER
HOWEVER, IMPERFECT FILTERS IN RECEIVERS ALLOW NEARBY FREQUENCIES TO ENTER THE RECEIVER AND INTERFERE WITH THE SIGNAL BEING RECEIVED FROM THE BASE STATION
PROPER FILTERS CAN REDUCE THE PROBLEM

40. CO-CHANNEL INTERFERENCE
CELLS FROM DIFFERENT CLUSTERS USING THE SAME FREQUENCIES ARE CALLED “CO-CHANNELS CELLS”
A CERTAIN MINIMUM DISTANCE MUST SEPARATE THESE CO-CHANNEL CELLS IN ORDER TO AVOID THE INTERFERENCE
FOR HEXAGONAL CELLS THE REUSE DISTANCE IS GIVEN BY :
REUSE DISTANCE ‘D’ = ( ) X R
WHERE, R : CELL SIDE, AND N: CLUSTER SIZE
THE REUSE FACTOR ‘q’ = D/R OR = 3N

41. CELL SPLITTING
CELL SPLITTING IS THE PROCES OF SUBDIVIDING THE CELLS INTO SMALLER CELLS EACH WITH ITS OWN BASE STATION AND SET OF CHANNEL FREQUENCIES
SPLITTING OF CELLS ALLOWS AN INCREASE IN THE DEGREE OF FREQUENCY REUSE THUS INCREASING THE CHANNEL CAPACITY OF CELLULAR NETWORK
IF THE RADIUS OF A CELL IS MADE HALF, FOUR TIMES AS MANY SMALLER CELLS COULD BE CREATED TO PROVIDE SERVICE TO THE SAME COVERAGE AREA
MAJOR DRAWBACK OF CELL SPLITTING IS MORE HANDOFFs PER CALL AND MORE PROCESSING LOAD PER SUBSCRIBER

42. CELL SPLITTING (CONTD.)
EXAMPLE OF CELL SPLITTING :
THE CHANNEL CAPACITY OF 7 MACRO CELLS WITH 10 CHANNELS PER CELL= 10 x 7 = 70 CHANNELS
AFTER SPLITTING THE MACRO CELLS INTO 4 MINICELLS, THE CHANNEL CAPACITY = 10 x 7 x 4 = 280 CHANNELS
AFTER SPLITTING MINI CELL INTO 4 MICRO CELLS, THE TOTAL CAPACITY = 10 x 7 X 4 X 4 = 1120 CHANNELS

43. SECTORING
THE CO-CHANNEL INTERFERENCE CAN BE REDUCED BY REPLACING A SINGLE OMNI-DIRECTIONAL ANTENNA AT THE BASE STATION BY SEVARAL DIRECTIONAL ANTENNAS, EACH RADIATING WITHIN A SPECIFIED SECTOR
THIS TECHNIQUE OF IMPROVING SYSTEM PERFORMANCE BY USING DIRECTIONAL ANTENNAS IS CALLED “SECTORING”
A CELL IS NORMALLY PARTITIONED INTO THREE 1200 SECTORS OR SIX 600 SECTORS

44. ROAMING
ROAMING REFERS TO EXTENSION OF CONNECTIVITY SERVICE IN A LOCATION THAT IS DIFFERENT FROM THE HOME LOCATION WHERE THE MOBILE SUBSCRIBER WAS REGISTERED
ROAMING ENSURES THAT THE SUBSCRIBER CAN CONTINUE WITH THE CALL WHEN MOVING AWAY FROM HIS HOME LOCATION WITHOUT LOSING THE CONNECTION
ROAMING IS POSSIBLE ONLY IF THERE IS AN AGREEMENT BETWEEN THE TWO NETWORKS PROVIDING SERVICES TO DIFFERENT AREAS

45. ROAMING PROCESS
WHEN A MOBILE DEVICE IS TURNED ‘ON’ IN A NEW LOCATION, THE “VISITED” NETWORK NOTICES THAT THE MOBILE SUBSCRIBER IS NOT REGISTERED WITH IT AND ATTEMPTS TO IDENTIFY THE HOME NETWORK OF THE SUBSCRIBER
IF ROAMING AGREEMENT EXISTS BETWEEN THE TWO NETWORKS, THE VISITED NETWORK CONTACTS THE HOME NETWORK AND REQUESTS SERVICE INFORMATION USING THE “IMSI” NUMBER
IF SUCCESSFUL, THE VISITED NETWORK MAINTAINS A TEMPORARY RECORD IN ITS DATABASE FOR THE SUBSCRIBER
LIKEWISE, THE HOME NETWORK UPDATES ITS DATABASE WITH THE CURRENT LOCATION OF THE SUBSCRIBER SO THAT IT CAN ROUTE THE CALLS CORRECTLY TO THE MOBILE DEVICE

46. HANDOFF / HANDOVER
CONTINUITY OF SERVICE IS MAINTAINED BY SUPPORTING HANDOFF / HANDOVER PROCESS WHEN A MOBILE SUBSCRIBER MOVES FROM ONE CELL TO ANOTHER
IT IS A PROCESS OF CHANGING THE CHANNEL RESOURCES (FREQUENCIES, TIME SLOT, CODE, ETC) ASSOCIATED WITH THE CURRENT CONNECTION WHILE A CALL IS GOING ON
IT IS INITIATED BY CROSSING A CELL BOUNDARY OR BY DETERIORATION IN THE QUALITY OF SIGNAL IN THE CURRENT CHANNEL

47. TYPES OF HANDOFFs TWO TYPES OF HANDOFFs ARE USED : HARD HANDOFF
SOFT HANDOFF

48. HARD HANDOFF IT IS A “BREAK BEFORE MAKE” PROCESS
CURRENT RESOURCES ARE RELEASED BEFORE NEW RESOURCES ARE USED
PRIMARILY USED IN TDMA / FDMA NETWORKS
THE BREAK IS SHORT ENOUGH TO BE NOTICED BY THE USER

49. SOFT HANDOFF IT IS A “MAKE BEFORE BREAK” PROCESS
CONNECTION WITH THE TARGET BASE STATION IS MADE BEFORE THE CONNECTION WITH THE EXISTING BASE STATION IS BROKEN
COMMONLY USED IN CDMA NETWORKS
THE SOFT HANDOFF GIVES MORE RELIABLE CONTINUITY WITH LESS CHANCES OF CALL TERMINATION THAN THAT IN HARD HANDOFF

50. FURTHER CLASSIFICATION OF HANDOFFs
NETWORK CONTROLLED HANDOFF
NETWORK MAKES THE HANDOFF DECISION
MOBILE ASSISTED HANDOFF
MOBILE MEASURES THE SIGNAL STRENGTH, BUT NETWORK MAKES THE DECISION OF HANDOFF
MOBILE CONTROLLED HANDOFF
MOBILE IS IN COMPLETE CONTROL OF THE HANDOFF PROCESS

51. MOBILE TO LANDLINE CALL

52. MOBILE TO LANDLINE CALL
PRE-ORIGINATION DIALING : WHEN SUBSCRIBER DIALS A NUMBER, THE DIALED DIGITS ARE NOT TRANSMITTED, BUT ARE STORED IN TH MOBILE MEMORY
THE CALL PROCESS STARTS WHEN THE USER PRESSES ‘SEND’ KEY
THE MOBILE SCANS ALL THE DEDICATED CONTROL CHANNELS AND LOCKS ONTO THE STRONGEST CHANNEL. ( CONTROL, PAGING, AND ACCESS FUNCTIONS ARE ON THE SAME CHANNEL)
WHEN THE REVERSE CONTROL CHANNEL (RECC) IS AVAILABLE, THE MOBILE TRANSMITS A ‘SERVICE REQUEST’ ON THE ‘RECC’ (CONSISTING OF DIALED DIGITS, ‘ESN’ AND ‘MIN’) TO THE CELL SITE
CELL SITE FORWARDS THE REQUEST TO MSC
MSC VALIDATES THE DATA (DIALED DIGITS, ‘ESN’ AND ‘MIN’) AND ROUTES HE CALL TO ‘PSTN’

53. MOBILE TO LANDLINE CALL (CONTD.)
THE CELL SITE SELECTS AN IDLE VOICE CHANNEL AND TRANSMITS AN ‘IVCDM’ (INITIAL VOICE CHANNEL DESIGNATION MESSAGE) TO THE MOBILE ON FORWARD CONTROL CHANNEL (FOCC)
‘IVCDM’ CONTAINS THE VOICE CHANNEL NUMBER, THE SUPERVISORY AUDIO TONE (SAT) AND THE VOICE CHANNEL MOBILE AUTHENTICATION CODE (VMAC)
SAT IS SNT ON THE ASSIGNED VOICE CHANNEL (FOVC)
MOBILE RECEIVES THE VOICE CHANNEL ASSIGNMENT, TUNES TO IT AND TRANSPONDS THE SAT ON REVERSE CONTROL CHANNEL ‘REVC’
If sat is lost for 5 seconds or more, the call is dropped
When the cell site receives the sat on revc, both audio paths are enabled and mobile user hears ringback from pstn
When the called party answers, the conversation begins
Blank and data burst signalling is used to transmit control information to the mobile during the call

54. LANDLINE TO MOBILE CALL

55. LANDLINE TO MOBILE CALL
LANDLINE PARTY DIALS THE MOBILE NUMBER
PSTN DETERMINES THAT THE CALL IS TO A MOBILE AND ROUTES THE CALL TO MSC
MSC PERFORMS VALIDATION OF DIALED DIGITS
A PAGE MESSAGE IS SENT FROM MSC TO THE CELL SITE ON FORWARD CONTROL CHANNLE (FOCC)
WHEN THE MOBILE SEES THE PAGE MESSAGE ON FOCC, IT RESCANS THE CONTROL CHANNELS AND LOCKS ON THE STRONGEST ONE
MOBILE TRANSMITS A PAGE RESPONSE MESSAGE ON THE REVERSE CONTROL CHANNEL (RECC)
CELL SITE RECEIVES THE PAGE RESPONSE AND SELECTS AN IDLE VOICE CHANNEL

56. LANDLINE TO MOBILE CALL (CONTD.)
CELL SITE TRANSMITS ON THE FORWARD CONTROL CHANNEL (FOCC) AN ‘IVCDM’ AND ‘SAT’ ON FORWARD VOICE CHANNEL (FOVC) TO MOBILE
MOBILE RECEIVES ‘IVCDM’ ON FOCC, TUNES TO THE ASSIGNED VOICE CHANNEL AND TRANSPONDS ‘SAT’ ON REVERSE VOICE CHANNEL (REVC)
CELL SITE TRANSMITS AN ALERT ON FOVC TO THE MOBILE ASKING THE MOBILE TO RING
MOBILE STARTS RINGING AND TRNSMITS SIGNAL TONE ‘ST’ CONTINUOUSLY UNTIL THE CALL IS ANSWERED
LOSS OF ST INDICATES THAT THE CALL HAS BEEN ANSWERED
MSC NOW CONNECTS THE LANDLINE PARTY TO THE MOBILE AND CONVERSATION BEGINS

57. MOBILE TO MOBILE CALL THE ORIGINATING MOBILE INITIATES THE CALL
CELL SITE RECEIVES THE DESTINATION MOBILE NUMBER AND ORIGINATING MOBILE’S ID ON REVERSE CONTROL CHANNEL (RECC) AND FORWARDS IT TO MSC
MSC SENDS A PAGING SIGNAL TO ALL CELL SITES TO LOCATE THE DESTINATION MOBILE
ONCE LOCATED, THE DESTINATION CELL SITE SENDS A PAGING SIGNAL TO THE DESTINATION MOBILE TO DETERMINE IF IT IS ‘ON’
AFTER RECEIVING A POSITIVE RESPONSE FROM THE DESTINATION MOBILE,VOICE CHANNELS ARE ASSIGNED TO BOTH ORIGINATING AND DESTINATION MOBILES

58. MOBILE TO MOBILE CALL (CONTD.)
CALL PROGRESS TONES ARE APPLIED IN BOTH THE DIRECTONS ( RING AND RINGBACK)
WHEN THE STSTEM RECEIVES ANSWER FROM THE DESTINATION MOBILE, CALL PROGRESS TONES ARE TERMINATED AND CONVERSATION BEGINS
IF THE SYSTEM FINDS THAT
ALL VOICE CHANNELS ARE ALLOCATED
SENDS ‘RETRY’ SIGNAL
DESTINATION MOBILE IS ON A CALL
SENDS ‘BUSY’ SIGNAL
DESTINATION MOBILE NUMBER IS INVALID
SENDS ‘CALL CAN NOT BE PROCESSED’ SIGNAL