training report
TRANSCRIPT
ATRAINING REPORT
ON
DIFFERENT SECTION OF HIMATNAGARBSNL EXCHANGE
MADE BY GUIDED BYMODI TEJAS M. (S-132807202) mr. m b suthar.
(s.d.e. tax)
1
HIMATNAGAR
This Is Certify That MODI TEJAS M (S-132807202). Student of SWAMI SACHCHIDANAND POLYTECHNIC COLLEGE (VISNAGAR) In Electronics & communication Department has successfully Completed his industrial training work on “C-DOT, OCB-283, CORDECT, MDF, POWER-PLANT, AND OVERVIEW OF GSM” During the period 07/01/2010 to 31/04/2010.
During his training period at BSNL (Himatanagar) he has sincerely and consistently done his project work. He was regular and took interest in the working of the exchange including all technical aspects.
TRAINING INCHARGE HIMATANAGAR (S.K.)
2
Knowledge is itself is a continuous process. At this moment of our substantial Enhancement, we rarely enough word to express our gratitude towards those who were constantly involved with me during my training
I would like to place on record my graceful thanks to people who helped me through the successful completion of the training.
I thank prof.B.G.Prajapati, who gave me his kind permission for working as a final semester on a subject in plant Industrial Training at BSNL Himatnagar.
The training at BSNL Himatnagar may be impossible without permission of D.G.M. of Himatnagar.so, I am thankful of Mr.
I would like to thanks Mr. , under his guidance I have completed my training. He gave kind permission to provide a learning plat6form in BSNL and the excellent infrastructure facilities made available. I would like to thank him for his guidance and time –to –time inspirational remarks than helps me in timely completion of the training.
I am sincerely indebted to Mr.
And would like to thank them for gave me invaluable guidance and support for all time. Also, thankful for their kindly and friendly behavior.
Last but not least, I would like to thank all staff of telephone exchange for help and support during my training period.
Thanks.
From:
3
ACKNOWLEDGEMENT I
1. INTRODUCTION TO TELEPHONE EXCHANGE 20
1.1 HISTORY OF TELECOMMUNICATION 21
1.2 TELEPHONE HISTORY 21
1.3 TYPES OF TELEPHONE EXCHANGE 21
1.4 ELECTRONIC EXCHANGE 22
2. MAIN DISTRIBUTION FRAME(MDF) 23
2.1 INTRODUCTION TO MDF 24
2.2 BLOCK-DIAGRAM OF MDF 25
2.3 DISCRIPTION 25
2.4 DROP-WIRES 25
2.5 CONNECTIONS 26
2.6 PRIMARY CABLES 26
2.7 DIFFERENT TYPES OF MDF 26
2.8 GAS DISCHARGE PROTECTORS 26
4
3. POWER PLANT 27
3.1 INTRODUCTION 28
3.1.1 TECHNICAL SPECIFICATION 28
3.2 PURPOSE OF THE POWER PLANT 28
3.3 FEATURES 28
3.4 FUNCTIONAL DISCRIPTION OF POWER SYSTEM 29
3.5 BLOCK-DIAGARM OF D.C. SECTION 29
3.6 RECTIFIER 30
3.7 POWER SYSTEM CONTROLLER 31
4. E-10B EXCHANGE 32
4.1 SYSTEM ARCHITECTURE 33
4.2 CONNECTION UNITS 33
4.3 SWITCHING UNIT 33
4.4 CONTROL UNIT 33
4.4.1 SWITCHING CONTROL UNIT 33
4.4.2 MANAGEMENT CONTROL UNIT 33
4.5 FUNCTION 33
4.6 MULTIPLEXING CONNECTION UNIT 34
4.7 FREQUNCY TX / RX 34
5
4.7.1 TONE GENERATOR 34
4.7.2 CONFERENCE CIRCUIT 34
4.8 FREQUENCY RECIEVER 34
4.9 AUXILARY EQUIPMENT RACK 35
4.10 SWITCHING NETWORK 35
4.11 CONTROL UNIT 35
4.11.1 MARKER 35
4.11.2 ROUTS THE PRINCIPLE MASSEGE 35
4.11.3 MULTI REGISTER 35
4.11.4 PROCESSOR 35
4.12 SWITCHING NETWORK CONTROL UNIT 35
4.13 TRANSLATOR 36
4.14 CHARGING UNIT 36
4.15 CHARGING FACILITY 36
4.16 MANAGEMENT CONTROL UNIT 36
4.16.1 DSF 36
4.16.2 OC 36
4.17 OTHER UNITS 36
4.17.1 BT 36
6
4.17.2 PGV
37
4.17.3 OMC 37
4.17.4 OPERATION 37
4.17.5 SUPERVISION 37
4.17.6 MAINTANANCE 37
4.17.7 CONNECTION UNIT 37
4.17.7.1 TYPES OF CONNECTION UNIT 37
4.18 SUPERVISION CONNECTION UNIT 37
4.18.1 ROLE 37
4.18.2 FUNCTION 38
4.19 STANDS ALONE FUNCTION 38
4.20 MULTIPLEX CONNECTION UNIT 38
4.20.1 PURPOSE 38
4.20.2 FUNCTION 38
4.20.3 RECEPTION URM 38
4.21 TRANSMISSION URM 38
4.22 OTHER FUNCTION 39
4.23 INTERFACE 39
4.24 FREQUENCY TX / RX UNIT 39
7
4.24.1 FUNCTIONS39
4.24.2 STRUCTUERS 39
4.25 FREQUENCY RECEIVER 39
4.26 TONE GENERATOR 39
4.27 CONFERENCE CALL CIRCUIT 39
4.28 CONTROL UNIT 40
4.29 REGISTER UNIT 40
4.30 INPUT & OUTPUT INTERFACE 40
4.31 EXCHANGER 41
4.32 OPERATION 41
4.32.1 INTERFACE OPERATION 41
4.32.2 REGISTER MEMORY OPERATION 41
4.32.3 COMPUTATION UNIT OPERATION 41
4.32.4 EXAMPLE 41
4.33 TRANSLATOR 42
4.33.1 FUNCTON 42
4.33.2 SPECIFICATION 42
4.33.3 STRUCTURE 42
4.33.4 EXCHANGE 42
8
4.33.5 TRANSLATOR MEMOARY 42
4.34 MARKER 42
4.34.1 FUNCTION 42
4.34.2 SPCIFICATION 43
4.34.3 SWITCHING NETWORK CONTROL UNIT 43
4.35 CHARGING SUIT STRUCTURE 43
4.35.1 CHARGING BLOCK 43
4.35.2 INPUT & OUTPUT INTERFACE 43
4.35.3 EXCHANGER 44
5. C-DOT DSS MAX 45
5.1 INTRODUCTION OF C-DOT DSS MAX 46
5.2 ADVANTAGES 47
5.3 DESIGN OBJECTIVES 48
5.3.1 SIMPLICITY 48
5.3.2 MAINTANANCE 48
5.4 TECHNOLGY 48
5.5 BASIC GROETH / BUILDING MODULES 49
5.5.1 THE SUBSCRIBER 50
5.5.2 THE TRUNKS 50
5.6 FUNCTION 50
9
5.7 ANALOG TERMINAL UNIT50
5.8 ANALOG SUBSCRIBER LINE CARDS 51
5.9 ANALOG TRUNK CARD 52
5.10 SIGNALLING PROCESSOR (SP) CARD 52
5.11 TERMINAL INTERFACE CONTROLLER 52
5.12 SPECIAL SERVICE CARD 53
5.13 DIGITAL TERMINAL UNIT 53
5.14 #7 SIGNALLING UNIT MODULE 53
5.15 TIME SWITCH UNIT 54
5.16 BASE MESSAGE SWITCH 54
5.17 TIME SWITCH 54
5.18 BASE PROCESSOR UNIT (BPU) 55
5.19 CENTRAL MODULE (CM) 55
5.20 SPACE SWITCH (SS) CONTROLLER 57
5.21 CLOCK DISTRIBUTION 57
5.22 CENTRAL MESSAGE SWITCH 58
5.23 ADMINISTRATIVE MODULE 58
5.24 INPUT & OUTPUT MODULE 58
5.25 REMOTE SWITCH UNIT 59
5.26 ALARM DISPLAY PANEL 59
5.27 NETWORK SYNCHRONIZATION IN C-DOT 59
10
5.27.1 LOCKED MODE59
5.27.2 HOLD OVER MODE 60
5.27.3 FREE RUN MODULE 60
5.28 FUNCTIONS OF NSC CARD 60
5.29 DIFFERENT CASES OF CALL SETUP 60
5.29.1 IN BM 1 60
5.29.1.1 LOCAL CALL SETUP 60
5.29.1.2 TIME SLOT ALLOCATION 61
5.29.1.3 DIAL TONES 61
5.29.1.4 DIGIT DIALLING 61
5.29.1.5 ROUTING 61
5.29.2 IN CM 61
5.29.2.1 PATH REQUEST 61
5.29.2.2 CAL REQUEST 62
5.29.3 IN BM 2 62
5.29.3.1 “B” FREES 62
5.29.3.2 RING 62
5.29.3.3 RBT 62
5.29.3.4 ANSWER 62
5.29.3.5 CONVERSATION 63
5.29.3.6 DISCONNECT 63
11
5.29.3.7 CLEAR FORWARD 63
5.29.3.8 RELEASE PATH 63
5.29.3.9 METERING 63
5.29.3.10 PARKING TONE 63
5.29.3.11 “B” BUSY 64
5.29.3.12 BUSY TONE 64
5.29.3.13 DISCONNECT 64
5.29.4 OUTGOING CALL SETUP 64
5.29.4.1 IN BM 1 64
5.29.4.1.1 ORIGINATION 64
5.29.4.1.2 TIME SLOT ALLOCATION 64
5.29.4.1.3 DIAL TONE 65
5.29.4.1.4 DIGIT DIALING 65
5.29.4.1.5 ROUTING 65
5.29.4.2 IN CM 65
5.29.4.2.1 PATH REQUEST 65
5.29.4.2.2 CALL REQUEST 65
5.29.4.3 IN BM 2 66
5.29.4.3.1 SIZE FORWARD 66
5.29.4.3.2 SEIZED FORWARD 66
5.29.4.3.3 RING BACK TONE 66
12
5.29.4.3.4 ANSWER66
5.29.4.3.5 CONVERSATION 66
5.29.4.3.6 DISCONNECT 67
5.29.4.3.7 CLEAR FORWARD 67
5.29.4.3.8 RELASE PATH 67
5.29.4.3.9 METERING 67
5.29.4.3.10 PARKING TONE 67
5.29.4.3.11 OUT PULSEING DIGIT 67
5.29.4.3.12 BUSY TONE 68
5.29.4.3.13 DISCONNECT 68
5.29.4.3.14 CLEAR FORWARD 68
5.29.4.3.15 RELEASE PATH 68
6. OCB TAX 69
6.1 INTRODUCTION 70
6.2 SYSTEM APPLICATION (NON-EXHAUSTIVE LIST) 70
6.3 GLOBAL NETWORK 70
6.4 CALLS HANDELDED 72
6.5 GENERAL PERFORMANCE DATA 72
6.6 FUNCTIONAL ARCHITECTURE 72
13
6.7 OCB 283 FUNCTIONAL ARCHITECTURE 73
6.8 PCM CONTROLLER 74
6.9 AUXILLARY EQUIPMENT MANAGER 75
6.10 CALL HANDLER 76
6.11 CALL CHARGING & TEAAIF MEASUREMENT 76
6.12 MATRIX SYSTEM HANDLLER 77
6.13 MASSEGE DISTRIBUTER 77
6.14 COMMUNICATION MULTIPLEX 77
6.15 SINGLE MULTIPLEX 77
6.16 OPERATION & MAINTANANCE 77
6.17 ROLE OF THE SWITCHING MATRIX SYSTEM 78
6.18 ROLE OF THE TRUNK CONTROL SYSTEM 81
6.18.1 IN PCM TO SWITCHING CENTER DIRECTION 81
6.18.2 IN SWITCHING CENTER TO PCM DIRETION 81
7. Cor DECT 82
7.1 INTRIDUCTION 83
7.1.1 ACCESS NETWORK 83
7.1.2 BACK BONE NETWORK 83
7.2 WLL 83
7.3 BASIC STANDARD OF THE DECT 84
14
7.4 N/W INTERFACE TO CORDECT
85
7.5 SYSTEM ARCHITECTURE 85
7.5.1 DIC 85
7.5.2 CBS 86
7.5.3 FRC 86
7.5.4 MWS 86
7.5.5 BSD 86
7.5.6 RBS 86
7.5.7 NMS 87
7.5.8 DECT 87
7.5.8.1 FUNCTION 88
7.6 FUNCTION PERFORM BY VARIOUS CARDS 88
7.6.1 CLOCK CARD 89
7.6.2 SWITCH CARD 89
7.6.3 BIMC CARD 89
7.6.4 BUIC CARD 89
7.6.5 TOCON 89
7.6.6 OSIF CARD 89
7.6.7 SYSTEM CONTROLLER 89
7.6.8 PWR MODULE 90
15
7.7 DIU FEATURES
90
7.8 CBS 90
7.9 FUNCTIONAL DISCRIPTION 91
7.9.1 THE LINE INTERFACE/POWER SUPPLY MODULE (LIPS) 91
7.9.2 THE BASEBAHD PROCCESSOR (BBP) 91
7.9.3 DIU INTERFACE MODULE (DIM) 91
7.9.4 AIR INTERFACE MODULE (AIM) 91
7.9.5 THE RADIO TRANS-RECEIVER SECTION 92
7.9.6 CBS ARCHITECTURE 92
7.9.7 ERLANG TRAFFIC HANDLING CAPABILITY OF CBSs 93
7.9.8 BASE STATION DISTRIBUTOR (BSD) 93
7.9.9 FIXED REMOTE SATATION (FRS) 93
7.9.10 MULTI-WALL SET (MWS) 93
7.9.11 RELAY BASE STATION (RBS) 94
7.9.12 FLEXIBILITY & RELIABILITY 95
7.10 SYSTEM APPLICATION CONFIGURATION 96
7.10.1 DIGITAL TRUNK MODE 96
7.10.2 RLU MODE 96
7.10.3 ITOS MODE 97
7.11TRAFFIC MEASURMENT & REPORTS 97
16
7.11.1 EXCHANGE OR BASE STATION MEASURMENT
97
7.11.2 TRUNK TRAFFIC MEASURMENT 97
7.12 TECHNICAL SPECIFICATION 98
8. GSM 99
8.1 INTRODUCTION TO GSM 100
8.1.1 GSM OPERATION REQUIREMENTS 100
8.1.2 SPECIFICATION 101
8.1.3 GSM MULTIPLE ACCESS 101
8.1.4 FDMA / TDMA 102
8.1.5 MODULATION METHOD (GMSK) 102
8.2 OVERVIEW OF GSM INTERFACES 103
8.2.1 AIR INTERFACE 103
8.2.2 A BITS –INTERFACE 103
8.2.3 A-INTERFACE 103
8.3 TYPES OF LOGICAL CHANNELS 103
8.3.1 TRAFFIC CHANNEL 103
8.3.1.1 TCH/ F (FULL) 103
8.3.1.2 TCH / H (HALF) 104
8.3.2 BROADCAST CHANNEL 104
17
8.3.2.1 BCCH 104
8.3.2.2 FCCH 104
8.3.2.3 SCH 104
8.3.2.4 CCH (COMMON CONTROL CHANNEL) 104
8.3.2.5 PCH 104
8.3.2.6 RACH 104
8.3.2.7 AGCH 105
8.3.2.8 DCH (DEDICATED CONTROL CHANNEL) 105
8.3.2.9 SACH 105
8.3.2.10 FACCH 105
8.3.2.11 SDCCH 105
8.4 GSM ARCHITECTURE 105
8.4.1 INTRODUCTION 105
8.4.2 GSM N/W STRUCTURE 106
8.4.3 GSM SERVICE AREA 106
8.4.4 PLMN SERVICE AREA 106
8.4.5 MSC SERVICE AREA 106
8.4.6 LOCATION AREA 106
8.4.7 CELLS 106
8.4.8 MOBILE STATION (MS) 106
8.4.9 FUNCTION OF MS 107
18
8.4.10 POWER LEVEL
107
8.4.11 SIM CARD (SUBSCRIBER IDENTIFICATION MODULE) 107
8.4.12 IMSI 108
8.4.13 TMSI 108
8.4.14 MOBILE STATION ISDN NUMBER 108
8.4.15 MSRN 108
8.4.16 IMEI 108
8.4.17 BSS (BASE STATION SYSTEM) 108
8.4.18 FUNCTION OF BTS 109
8.4.19 BSC 109
8.4.20 MSC 109
8.4.21 FUNCTION OF MSC 110
8.4.22 VLR 110
8.4.23 HLR 110
8.4.24 OMC 110
8.5 SERVICES 110
8.5.1 GSM SERVICES 111
8.5.1.1 BEARER SERVICES 111
8.5.1.2 TELE SERVICES 111
8.5.1.3 SUPPLIENTARY SERVICES 111
19
8.5.2 LINE IDENTIFICATION SERVICES
111
8.5.2.1 CLIP 111
8.5.2.2 CLIR 111
8.5.2.3 COLR 112
8.5.3 CALL OFFERING SERVICES 112
8.5.3.1 CFU 112
8.5.3.2 CFB 112
8.5.3.3 CALL FORWARDING 112
8.5.4 CALL COMPLATION SERVICES 112
8.5.4.1 CALL WAITING 112
8.5.4.2 HOLD 112
8.5.5 MULTI PARTY SUPPLIMENTARY SERVICE 113
8.5.5.1 MPTY 113
8.5.6 CHARGING SUPPLIMENTARY SERVICE 113
8.5.6.1 AOCI 113
8.5.6.2 AOCC 113
8.5.7 CALL RESTRICTION SERVICES 113
20
21
1.1 HISTORY OF TELECOM:-
1. First Telegraph-1851 Calcutta.2. Telegraph Services Open For Public-1855.3. Telephone invented in 1876 By Dr.Alexander Graham Bell.4. First telephone exchange in India-30’Th Jan.1982.5. Up to 1984 it is known as P&T Department.
22
6. Jan.1985 DOT is separated.7. In 1989 telecom commission constituted.8. In 1986 MTNL is formed.9. In 1987 telecom regulatory authority of India constituted.10. NOV.1999 DOT is divided into DOT and DTS.11. 01-10-2000 BSNL is formed in modasa.
1.2 TELEPHONE HISTORY:-
1. Magneto telephone.2. CB Telephone(Central battery)3. HMT telephone(Hand Micro Telephone)4. P.D. telephone(Priya Darshini)5. 671 type telephone.6. 677 type telephone .7. EPBT (Elect. Push Button Type)8. Cellular/Pager (WILL-Wireless In Local Loop)
1.3 TYPES OF TELEPHONE EXCHANGE:-
1.4 ELECTRONIC EXCHANGE:-
23
TYPES OF TELEPHONE EXCHANGE
MANUAL
MAGNETO CBNM CBM PBX
AUTO
STROWSER
MAX 1
MAX 2
MAX 3
CROSS BAR
NEC 400
IPT 400
ELECTRONICS
ANALOG DIGITAL
24
ELECTRONIC EXCHANGE
ANALOG SWITCHING SYSTEM
PRX FETEX ND 10
DIGITAL SWITCHING SYSTEM
E10B AT&T OCB C-DOT
C-DOT 128 P
C-DOT 256 P
C-DOT 512 P
C-DOT 2048 P
2.1 Introduction to MDF:-
25
The fig. shows the main distribution frame
26
2.2 BLOCK-DIAGRAM OF MDF:-
Above block diagram shows the inter connection between the Subscriber and the Exchange Via MDF.
2.3 DESCRIPTION:-
The MDF for base modules exchange can cater to the total of 512 lines and Trunk Termination on the line side.On the exchange side, provides for terminating 512 ports.Adding similar units can enhance the capacity.As per our requirement, the main function of the MDF is to provide the connection between the subscriber and the exchange.To cater to an ultimate requirement 2048 ports for single base model exchange.The subscriber’s line enters exchanges through no. of large capacity U/G (UNDER GROUND) Cables, each of which serves a different part of exchange area.Subscriber line is connected to exchange side via Jumper.
2.4 DROP WIRES:-
Every subscriber in Telephone network is connected generally to nearest Distribution point by means of dedicated pair of drop wire.This wire is terminated at D.P.( Distribution point).The cable form pillar to D.P. is called Distribution cable.
27
2.5 CONNECTION:-
The 128 twisted pair cable comes from the exchange and terminated at the exchange side in horizontal tag blocks.This tag block has 16 columns & 8 rows so total 128 cells and hence each UTP has terminates at one cell & can be identified by the color coding, from line side of the tag blocks 128 UTP pair now terminates on the vertical tag blocks at the front of the tag blocks.This vertical tag blocks has 100 cells in matrix of 20(rows)*5(columns) =100, and from this vertical tag blocks pairs goes under ground to the cabinets.
2.6 PRIMARY CABLES:-
The cable laid from MDF to cabinet is called primary cables as shown in block diagram by bold lines. The cable laid from cabinet to pillar is called secondary cables as shown in block diagram by light lines.
2.7 DIFFERENT TYPES OF MDF:-
There are mainly two types of MDF:
1) WALL TYPE.2) RACK TYPE.
In present days mainly Rack type MDF is used. Red and white color jumper wires are used to jumper line side termination to the exchange side termination.The pair of contact on appropriate line side connector module, which requires being module.For protection of exchange equipment against over voltage, Gas discharging tubes are clipped on line side. They are called FUSES.
2.8 GAS DISCHARGE PROTECTORS:-
In case of heavy lighting discharge of high voltages, gas discharge protectors are used as protective device to protect the communication exchange equipment communication equipments from damage due to high voltages.The gas discharge protector consists of two or three tungsten electrode sealed in a special glass envelope.
28
3.1 INTRODUCTION:-
29
RMPS NX25 A/D is a Power System of ultimate capacity of 200 A and Suitable for VRLA (Value Regulated Lead Acid) Batteries.
3.1.1 TECHNICAL SPECIFICATION:-
Input(Single phase A.C.): Voltage:- Normal:-230V Range:-150 to 275V Frequency:- 48 to 52hz.
Output (Single phase A.C.): Voltage:- Normal:- -48.0 to -54.0V MAX.:- -55.2V
3.2 WHAT IS THE PURPOSE OF THE POWER PLANT?
The power system is intended primarily to provide uninterrupted D.C. Power to the Telecommunication equipments and current for charging the Batteries.The System works from commercial A.C. mains Supply (Single Phase,3 wire, 50 Hz) Which is rectified & regulated to -54V DC & is fed to the exchange.The system supports 3 parallel sets of VRLA batteries & charges them simultaneously to ensure uninterrupted DC power to the equipment.
3.3 FEATURES:-Single Rack Configuration.Facility to parallel 8 nos. of 48V/25V (1400W) Rectifier modules operating from single phase, 230V, 50Hz AC Input.Termination for 3 sets of batteries & equipments.The System input Single –phase 3-wire, 50Hz Supply.The power system has a single bus called auto float/charge bus. Depending upon the status of the batteries, the output DC Voltage is maintained at 54V under auto float condition.The System employs natural convection cooling and has AC input distribution, DC output Distribution, protection and alarm circuitry for Rectifiers, battery and equipment.
3.4 FUNCTIONAL DISCRIPTION OF POWER SYSTEM:-
30
There is Two type of functionality of power system:
1) A.C. DISTRIBUTION.2) D.C. DISTRIBUTION.
A.C. SECTION :-
The system works from commercial A.C. supply (Single Phase,3 wire, 50 Hz).This A.C. supply is of 230 Volts. For this commercial power supply, BSNL power plant gets 11KV, 1600A supply from G.E.B. Power lines.11KV converted to 230V by Step down Transformer via HT supply, Oil ckt Breaker.
D.C. SECTION:-
230V single phase A.C. supply with 3 wires of 50HZ is Converted, Regulated & Rectified to -54V D.C. supply & fed to the equipment.The conversion & Rectification is done through ckts called FRBS CUM SC (Float Rectifier Battery Charger cum Silicon Controlled Rectifier) but these functions done through modular ckts which require less space.
3.5 BLOCK DIAGRAM OF D,C, SECTION (FRBC CUM SC):-
3.6 RECTIFIER MODULES:--
31
The SMPS rectifier module works on 230V with AC input.The input is fed through 3-pins AC Sockets.The status and fault indication are available on the front panel of the module.The control signals coming from power system controller on an 8-pins flat cable are also terminated on a FCC connector (8-pole) available on front panel.The rectifier modules are convection cooled and be jacked in and out of the cabinet easily.
SMPS :-
Battery:-
32
3.7 POWER SYSTEM CONTROLLER:-
The Power System Controller (PSC) is a microcontroller based unit to control the complete functioning of the power system. It consist of following:-
Controller card TEMCO Card Power supply module LCD Module Keypad Sensing Transformer
The controller card is the main CPU of the nit. This card on the basis of measurement section of this card takes decision to keep system healthy.TEMCO card is responsible for temperature compensation for battery voltage.Power supply module is powers source for PSC.LCD module is used to display various measurement result and error message.Keypad is used for man-machine communication. Sensing transformer is used to sense the incoming AC phase.
THE PSC PROVIDES 13 LEDS ON THE FRONT PANEL TO INDICATE VARIOUS STATUS AND ERROR CONDITION AS SHOWN IN TABLE BELOW:-
CONDITION LED COLORMAINS AVAILABLE GREEN LEDMAINS OUT OF RANGE RED LEDFR/FC FAIL RED LEDBATTERY ISOLATED RED LEDLOAD VOLTAGE LOW RED LEDLOAD VOLTAGE HIGH RED LEDMAINS ON/BTY DISCHARGE RED LEDSYSTEM OVERLOAD RED LEDTEMCO FAIL RED LEDFR/FC IN FLOAT GREEN LEDFR/FC IN CHARGE YELLOW/AMBER LEDBATTERY FAILED/NO BATTERY RED LEDVOLTAGE DROP RED LED
33
4.1 SYSTEM ARCHITECTURE:-
34
E-10B system is built of blocks listed below:
CONNECTION UNITS SWITCHING NETWORKS CONTROL UNITS OMC (OPERATION AND MAINTENANCE)
4.2 CONNECTION UNITS:-
URA (CSE): SUBSCRIBE4R CONNECTION UNIT URM: MULTIPLEX CONNECTION UNIT ETA: FREQUENCY SENDER/RECEIVER UNIT BDA: AUXILIARY EQUIPMENT RACK
4.3 SWITCHING UNIT:-
RCX: Switching network
4.4 CONTROL UNIT:-
4.4.1 Switching control units:-
MR: Multi register TR: Translator TX: Charging unit MQ: Marker
4.4.2 Management Control Units:-
OC: Monitoring Unit DSF: Standby Charging Recording unit
4.5 FUNCTION:-
Power feeding to the subscriber lines (-54V). Detection of Off hook/On hook conditions A/D, D/A conversions
Transmission of::-
Ringing current Home metering pulse
CSE Performs B O R S H C T Functions:-
B= BATTERY FEED C= CODING (A/D & D/A CONVERSION)
35
H= HYBRID (2/4 & 4/2 WIRE CONNECTIONS) O= OVER VOLTAGE PROTECTION R= RINGING CURRENT S= SUPERVISION T= TWSTING (Subscriber Lines & Circuits Testing)
4.6 MULTIPLEXING CONNECTON UNIT (URM):
Acts as PCM interface with CSEDS & other exchange. Connect CSEDS to E-10B host via PCM Connect junction to form E-10B
4.7 FREQUENCY SENDER/RECEIVER UNIT (ETA):-
Two types of modules in ETA :-
4.7.1 TONE GENERATOR:-
ETA-1, ETA-2 are equipped with three tone generators each called GT1, GT2, GT3 which respectively generate standard tone like busy tone, dial tone, warning tone, ring back tone.
4.7.2 CONFERENCE CIRCUIT:-
An ETA can accommodate up to two CCF modules. Each module provides 8 conference circuits and hence capable of handling 8, 3-party conference calls.
A conference circuit is required for:-
Call waiting facility Trunk offering
4.8 FREQUENCY RECEIVER (RF):-
Every ETA can have two RF modules: RF-1 & RF-2
RF receivers: DTMF frequency
4.9 AUXILIARY EQUIPMENT RACK (BDA):-
One rack per exchange Single processor, Intel 8085 Providing 16 recorded announcements
36
4.10 SWTCHING NETWORK (CK):-
Three stage T-S-T switching network
4.11CONTROL UNIT:-
There are four sub parts of Control Unit:-
4.11.1 MARKER (MQ):-
Interface between connections units & multi register switching network & control unit.
Message distributor.
4.11.2 ROUTS THE PRINCIPLE MASSEGE:-
Control units- switching network Connection unit MR Both MQ works on load sharing basis
4.11.3 MULTI REGISTER (MR):-
Heart of the system Takes decision in real time, during call set up & release Each MR can handle 256 calls simultaneously Control, consults, orders, requests other units on receiving digits, subscriber
loop conditions etc. -2-6 MR in an exchange: one rake pre MR.
4.11.4 PROCESSOR:-
ELS-48 Macro program subsystem.
4.12 SWITCHING NETWORK CONTROL UNIT (UGCX):- 2UGCX 0>MQ1>MQ2
Each UGCX is connected to:- Associated marker by internal bus Each MR & TX by dedicated LX line.
4.13 TRANSLATOR (TR):-
Two per exchange: one rack per TR Load sharing mode Stores office data (including subscribes & circuits characteristic) Consulting by MR at differ stages of call setup Processor: ELS 48
37
4.14 CHARGING UNIT (TX):-
Handles call charging functions. Can charge up to 2000 ordinary call at time. 2 TX together can charge up to 4000 calls. Does detail billing. Stores subscriber meter in auxiliary memory. Works under the control of MR.
4.15 CHARGING FACILITIES:- 7 types of days are possible e.g. normal, Sunday & national holiday. Local charging or tax dependent charging for STD calls. Meter unit by the exchange earned over any period can be known.
4.16 MANAGEMENT CONTROL UNIT:
4.16.1 DSF (Stand By Charge Recorder):-
(Detail billing save device) Note a standby to TX Has an agape unit Normally inactive Detail billing data
4.16.2 OC (Monitoring Unit):-
Interface between exchange & OMC: Store most of the traffic observation counter. If OC is down, on dialogue possible between OMC & exchange unit.
4.17 OTHER UNITS:-
4.17.1 BT (Time Base):-
Synchronizes the operation of various unit. Generator clock signal &distribute to all unit.
4.17.2 PGV (General Visual Display):-
Display alarm condition of exchange & its RLU. Controlled by BDA.
4.17.3 OMC (Operation & Maintenance Center):-
38
Control operation maintenance & supervision function of exchange.
4.17.4 OPERATION:-
Management of subscriber lines circuit, circuit group charging etc.
4.17.5 SUPERVISION:
Testing of subscriber lines, circuit and load observation.
4.17.6 MAINTENACE:-
Processes faults, alarms etc.
4.17.7 CONNECTION UNIT:-
The connection unit comprises basically of equipment system subscriber lines and equipment that sends a-ND receives audio frequency signaling samples.
4.17.7.1 There are three types of connection unit:-
URA-subscriber connection unit (local and distant). URA-multiplex connection unit for connecting to other exchanges. ETA-frequency sender receiver circuits.
4.18 SUBSRIBER CONNECTION UNIT:-
4.18.1 ROLE:-
It provides connection up to 1024 subscriber lines, may be located in same premises as the exchange (local era) in satellite exchange both are of same construction and same equipment whether of the local or distance type Enable the connection of rotary dial, push button telephones.
4.18.2 FUNCTION:-
It is utilized in connection and power feed on subscriber lines and sending ringing current it is also utilized in transmission of indication of loop state change to the control unit (subscriber going off or hook connection) it is also used in transmission of digit and transmission of appropriate units of battery reversal.
4.19 STANDS ALONE FUNCTION:-
39
Scanning equipment to identify calling subscriber. A/D conversion Traffic observation Switching UR to supervision mode so that supervision of call is carried out
by connection unit Search a root to a called party. Subscriber line test External interface for connection Subscriber The interface for connection of URA to the exchange.
4.20 MULTIPLEX CONNECTION UNIT:-
4.20.1 PURPOSE:- Multiplex connection unit URA is the interface between switching network
and distance connection unit (UARD) of circuit from other exchange. UMR has two module provides connection of 2.048 MBPS links from distant URA. The MRS module in the UMR provides connection for the other circuits.
4.20.2 FUNCTON:-
Transmission and reception of 30 channel PCM links.
4.20.3 RECEPTION URM:-
Conversion of HDB3 code to binary form. Resynchronization with subscriber exchange. Clock code conversion of ‘E’ wire signaling into internal code recognizer by
MR.
4.21 TRANSMISSION URM:-
Reconstitution of PCM frames Transmission of HDB3 from of exchange Code conversion to match signaling of ‘M’ Wire of circuits.
4.22 OTHER FUNCTION:- Detection of PCM alarms and transmission to OMC Self diagnosis of internal failure
4.23 INTERFACE:-
The external interface for connection of URADs. To exchange, other circuits (other exchanges). Internal interface connects URA to switching network, MR & MQ.
4.24 FREQUINCY SENDER & RECEIVER UNIT:-
40
4.24.1 FUNCTIONS:-
Reception of MF signaling, push button signaling. Generation of usual tones & MF tones. Setting of conference call connection.
4.24.2 STRUCTURE:-
Two frequency Unit RF1 & RF2. Three tone generator unit (GT1, GT2, GT3) Two conference call circuits (CF1, CF2).
4.25 FREQUINCY RECEIVER:-
It is designed to handle : MF signaling codes Frequency combination from push button telephone
The frequency is obtained from switching net work via LRS links. A RF unit is equivalent to 31 basic receivers. Each channel is non-dedicated in other word it may be used in differently for receiving push button cods, MF codes etc.
4.26 TONE GENARATOR:-
The tone generator provides following signal in digit from. The standard tones used in an automatic exchange.
4.27 CONFERENCE CALL CIRCUIT:-
The conference call circuit can handle 8 conference call simultaneously, each involving 4 subscribers
Provides a call offering facility, in which the operator can break into a call. Already, setup to offer called party opportunity to connect on a common
switch circuit one subscriber receives combination of signals sent out by the other 3 subscribers.
4.28 CONTROL UNIT:-
Control unit comprises of multi registers, marker, translator, charging unit, monitoring unit & stand by charging unit as shown in below fig.-
41
The MR comprises two units. Register unit and exchanger separated by I/O interface.
The register unit is central unit of MR. this is based on program, associated micro program and a register memory. The exchange controls communication between MR & other units of exchange it command processor and modules connected to various communication links. The I/O interface is a RAM that can be addressed by registers units & exchanger. It also includes modules providing access to connection unit & switching unit & switching n/w.
4.29 REGISTER UNIT:-
The main function of register is to store data required for setting up & releasing of calls.
These units comprises of register memory with associated additional data memory, micro programmed computation unit& programmed memory
The register can hold up to 256 register the cyclic time of these register is 8 ms.
4.30 I/O INTERFACE:- I/O interface is located between register unit& exchanger. It comprises a set
of I/O buffers. They are implemented by a RAM which is addressable on a time sharing by the register unit
An associated re-synchronization module whose function to synchronize multiplex LT links from TR.
4.31 EXCHANGER:-
The exchanger is responsible for massage. Transmission between units & control the associated I/O buffers
42
It comprises of standard logic equipment. LM module LC module The ELS is processor for control unit’s communication. It enables the
register to exchange data with other control units of exchange via I/O buffer memory & link access module. It has its own programmed memory.
4.32 OPERATION:-
4.32.1 INTERFACE OPRATION:-
These are dedicated buffer memory located between register unit & exchanger
The output buffer are written by the register & read by exchanger.
4.32.2 REGISTER MEMORY OPERATION:-
The register memory comprises:-
Data memory which can store 256 register simultaneously Two buffer memories (MTE0 & MTE1) for storing one register
4.32.3 COMPUTATION UNIT OPRATION:
At every 8 ms a register processes an instruction of the program which correspond to given state in the setting up or releasing of calls.
These program instructions are present at the micro program computation units for 31.25 us. These intervals are subdivided into 32 slots to execute.
A subscriber goes off hood the marker receiver the corresponding message from the connection unit to which the subscriber is connected via link LM, the market send these message to the LM module of the available MR.
The first available register is in one of the MTE.
4.32.4 EXAMPLE:-
In case of local call between two dial telephones subscriber connected to distant subscriber connection unit, when the MR has calling party’s characteristic in a register. It interrogates the translator to find out the associated discrimination of they are such as to authorize the setting up of the call the calling party is present.
4.33TRANSLATOR:-
4.33.1 FUNCTION:-
43
The translator provides the multi register on request with data subscriber and the circuits required setup and releasing the calls.
Translates the prefixes and the first digits received from the calling party Executes, in conjunction with the OMC all operation management,
maintenance, and test function. Controls the services such as call forwarding abbreviated dialing hot line etc.
4.33.2 SPECIFICATION:-
The translator is one of the control units of an E-10B exchange and the operating on a load-sharing basis
The translator uses programmed logic and stores in file data on the subscriber’s circuits connected to the exchange.
The translator data may be written, detected or modified at will from the OMC.
4.33.3 STRUCTURE:-
The exchanger who receives and sends out data on the links connected to the translator, the exchange being connected to the translator memory.
The translator memory, which contain the translator file and write and read.
4.33.4 EXCHANGE:-
The exchanger processes the request others units of the exchange using the data in translator memory it comprises of:-
The standard logic equipment (ELS). The LM module The multiplex module for LT
4.33.5 TRASLATOR MEMORY:-
The translator memory stores data of subscriber circuit connected to exchange, in the form of files.
4.34 MARKER (MQ):-
4.34.1 Function:-
The marker is responsible for routing the principle switching message between the several exchanges.
Send the call to CSEL or CSED. Receives from the MR for sending to the switching n/w. Send message to end receiver message from OMC.
4.34.2 SPCIFICATION:-
44
The marker is one of control unit of E-10B exchange connected to the order control units the switching network and subscriber and multiplex connection unit.
Each E-10B exchange includes two markers operating on load sharing basic. The marker is a dedicated unit using programmed logic
The marker is divided into two units: The first one is the exchanger who provides communication with the control
units and between the connection units and control units. The switching network control unit (UGCX), which is connected to the exchanger, provides the interface between the markers.
The exchanger comprises: The standard logic equipment (ELS) The LM module The LC module The LU module
4.34.3 SWITCHING NETWORK CONTROL UNIT:-
Check for correct execution of requested functions Under the control of MR& TX sets up & release connection & send out the
signals. The charging unit & control unit, which is connected to the switching
networks, the multiplex connection units, the MR, the stand by charge recording unit & to the OMC.
4.35 CHARGING SUIT STRUCTURE:
4.35.1 CHRGING BLOCK:-
The charging block comprises: The register memory The micro programmed computation unit same as MR.
4.35.2 I/O INTERFACE:
The module made up of indented block as in the MR.
4.35.3 EXCHNGER:
As in the MR, the exchanger comprise a standard logic equipment with the associated programmed and the LM, & LC module same as in the MR.
45
Two modules specific to the charging unit are connected to the exchanger in the form of the clock module.
The clock module includes a series of counters controlled by the time base of the exchange. It provides the second, minute, hour & day in the decimal. The exchanger can read and write in these counters.
46
5.1 INTRODUCTION OF C-DOT DSS MAX:-
47
The C-DOT DSS MAX (Center for Development of Telemetric Digital Switching
System Main Automatic Exchange) is a one kind of exchange, which can be used as
a universal digital switch. It is used for different application as:
Local
Transit
Integrated local & Transit
High traffic/load handling capacity up to 8,00,000 BHCA(BUSY HOUR CALL
ATTEMPT) with termination capacity of 40,000 lines as local exchange or 15,000
Trunk Automatic Exchange (TAX).
48
In C-DOT DSS MAX, two types of configurations are envisaged at CM level
depending on the no. Of BMs connected to it:
The first one is MAX-L(Main Automatic Exchange-Large),which supports a
maximum of a 16 BMs.
The second one is MAX-XL(Main Automatic Exchange-Extra Large),which
supports a maximum of 32 BMs.
The maintenance procedure for SBM(Single Base Module) and MBM(Multi
Base Module) are same except that:
In SBM exchanges, IOPs are connected to BP(Bas Processor) in BM (Base Module)
rack whereas in MBM it is connected to AP(Administrative Processor) in CM
(Central Module) rack.
Additional maintenance procedure of CM rack, which is used only in MBM
exchanges.
Different ADP (Alarm Display panel) for SBM and MBM exchanges are connected
to BP and AP respectively.
5.2 ADVANTAGES:-
Standardized components
Commonality in hardware
Documentation, Training, installation and field support for a products and
minimization of inventory of spares.
Reducing the number and type of cards.
Flexible system growth.
Easy to maintain.
5.3 THE MAJOR DESIGN OBJECTIVE OF THE C-DOT DSS MAX ARE
49
5.3.1 SIMPLICITY:-
Layered architecture, neat and well-defined Massa interfaces between modules.
5.3.2 MAINTANANCE:-
Use of high-level languages proper documentation and modular design, increased reliability due to fault tole.
5.4 TECHNOLOGY:-
This system employs a T-S-T (Time-Space-Time) switching configuration .
It is based on a 32 channels PCM structure.
It is use basic rate of 64 Kbps and 2 Mbps primary multiplexing rate.
Control is distributed over the system by using 32 bits 16 bit and 8-bit
microprocessor.
All the critical circuitry has built in redundancy.
System hardware utilizes advanced concept in microelectronics for a
compact and optimum design.
50
Basic memory unit has been implemented as a 16 MB dynamic RAM board.
Single chip digital signal processors are used for implementing DTMF and
MF receivers.
A high performance, high density VLSI chips detects multiple tone and
simultaneously performs signal filtering on 4 channels. This approach
reduces costs, power dissipation and space on the PCBs.
Analog to digital conversion has achieved by using a per channel coder
decoder (CODEC) CHIP.
Customization based on ASICs/FPGAs has been used to optimize space
utilization and reduce the number of components on the lin cards.
5.5 BASIC GROWTH/BULDING MODULES:-
C-DOT DSS MAX exchanges can be configured using four basic modules:-
BASE MODULE(BM):-
Base Module is the basic building block of C-DOT DSS MAX. It interfaces the subscribers, trunks and special circuits.
5.5.1 THE SUBSCRIBERS MAY BE:-
51
The individual or grouped PBX (Private Branch Exchange) lines.
Analog or digital lines.
5.5.2 THE TRUNKS MAY BE:-
Two wire physical.
E&M (Ear And Mouth) 4 wire.
Digital CAS9Channels Associated Signaling).
CCS (Common Channel Signaling).
5.6 FUNCTIONS:-
Analog to digital conversion of all signals on analog lines an trunks.
Interface to digital trunks and digital subscribers.
Switching the calls between terminals connected to the same BM.
Communication with the Administrative Module via the Center Module for
administrative and maintenance functions and also for majority of inter BM
switching (call processing) functions.
Provision of special circuits for call processing support that is digital tones,
announcements, MF or DTMF sender/receivers.
Provision for local switching and metering in stand alone mode remote switch unit.
5.7 ANALOG TERMINAL UNIT(ATU):-
To interface analog lines/trunks and providing special circuits as conference,
announcements and terminal tester.
It is used for interfacing 128 analog terminations, which may b lines or
trunks.
It consists of terminal cards, which may be a combination of Line ckts Cards
(LCC), CCB with metering (CCM) cards, Two Wire Trunk (TWT) cards ,
E&M Two Wire (EMT) Trunk cards and , E&M Four wire (EMF) Trunk
52
cards depending upon the module configuration. Also, provision has been
made to equipment Conference (CNF) card to support “six party”
conference, Announcement (ANN) to support 15 user friendly
Announcement massages, and Terminal Test Controller (TTC) for testing of
analog termination. Power Supply Unit (PSU-I) provides logical voltages and
ringing current in the ATU.
5.8 ANALOG SUBSCRIBERS LINE CARDS:-
Two variants of subscriber line cards as LCC or CCM with interfaces up to 8
subscribers provide basic BORSCHT functions for each line. Above
BORSCHT function are as follows:
B=battery feed
O=Over Voltage protection
R=Reversal
S=Signaling
C=Coding and decoding
H=Hybrid
T=Testing
A-D conversion is done by per-channel CODEC according to A-low of Pulse
Code Modulation.
Each CCM card has the provision of battery reversal or all the 8 lines with
the last two lines having provision to generate 16 KHz metering pulses to be
ser to subscribers metering equipment.
The 8-bit digital (voice) output of four LCCs is multiplexed to form a 32
channel, 2 Mbps PCM link-also called a Terminal Group (TG).
Since a terminal unit has a maximum of 16 terminal cards, there are four
terminal groups. The signaling information is separated by a scan/drive login
circuit and is sent to the signaling processor on four different scan/drive
signals.
The LCC/CCM also provides test access relay to isolate the exchange side
and line sided to test it separately by using the TCC.
53
5.9 ANOLOG TRUNK CARDS:-
These cards interface analog inter-exchange trunks which may be of three
types as:
EMT
EMF
These interfaces are similar to subscriber line card. With only difference that
the interfaces are design to scan/drive events on the trunks as per pre-defined
signaling requirement.
5.10 SIGNALLING PROCESSOR (SP) CARD:-
It processes the signaling information received from the terminal cards. This
signaling information consists of scan/drive function like:
Origination detection
Answer detection
Digit reception
Reversal detection
Based on the information received from the TIC, it also drives the event on
the event on the selected terminal through scan/drive signals.
5.11 TERMINAL INTERFACE CONTROLLER (TIC) CARD:-
It controls the four terminal groups (TG) of 32-channels and multiplex them
to form a duplicated 128-channel, 8 Mbps link towards the time switch (TS).
For signaling information of 128-channel, it communicate with signaling
processor (sp) to receive/send the signaling event on analog terminations. It
also uses one of the 64 Kbps channel out of 128 channels towards TS, to
communicate with BPU.
TIC is built around 8-bit microprocessor with associated memory and
interface and it is duplicated for redundancy.
5.12 SPECIAL SERVICE CARDS (SSC):-
54
A TU has some SSC such as conference (CNF) card to provide “six party”
conference. Speech samples from five parties are:-
Added by in built logic and sent to the sixth party to achieve conferencing.
TTC (Terminal Test Controller) card is used to test analog terminal
interfaces via the test access relays on the terminal cards.
ANN (Announcement Controller) card provides 15 announcements on
broadcast basis.
5.13 DIGITAL TERMINAL UNIT (DTU):-
For interfacing digital trunks i.e. 2Mbps e-1/PCM LINKS. It is used to
interface digital trunks.
One set of DTS (Digital Trunk Synchronization) card alone with the DTC
(Digital Trunk Controller) card is used to provide one E1 interface share four
TGs in a DTU.
The scan functions are HDB3 to NRZ (Non Return to Zero) frame alignment
and reconstitution of the received frame. Each interface can be configured as
CAS or CCs interface.
5.14 #7 Signaling Unit Module:-
To support ss7 protocol handlers and some call processing function for CCS7
calls.
Any one of the ATU or DTU in a BM can be replaced be SUM France to
support CCS7 signaling.
5.15 TIME SWITCH UNIT(TSU):-
55
MF/DTMF controller(MFC).
5.16 BASE MESSAGE SWITCH (BMS):-
It routes the control messages within the BM, across different BMs and also
AM via the CM.
It is implanted around two different cards as message switch controller
(MSC) with six direct HDLC links and the message switch device (MSD).
It acts as a message transfer point between the BP an controllers.
NOTE:- To support 8,00,000 BHCA, MSC and MSD cards are replaced by a high performance Message Switch (HMS) with high speed, 32-bit microprocessor (MC 68040).It implements 38 HDLC links with flexibility of programming individual for a speed up to 750Kbps.
5.17 TIME SWITCH (TS):-
It is implemented using three different functional cards as:
Multiplexer/demultiplexer (TSC).
Time switch (TSS).
Time Switch Controller (TSC).
It multiplexes above 128 channel links to form a dual 512 channel, 4Mbps
multiplexed bus towards the CM. The individual buses are called bus-0 and bus-1.
5.18 BASE PROCESSOR UNIT (BPU):-
56
For control message communication and call processing function.
It is the master controller in the BM. It is implemented as duplicated controller with
memory units. This limited sub units are in the form of:
Base processor controller card (BPC).
Base memory extender card (BME).
BPC controls time switching, communicates with the AM and directly interfaces
with the ADP and IOM in SBM.
NOTE:- To support 8,00,000 BHCA, the BPC card is replaced be high performance processor
card (HPC). It is pin to pin compatible for hardware and software so that they are interchangeable
at any site to meet specific traffic requirement.
5.19 CENTRAL MODULE (CM):-
CM is responsible for space switching of inter-base module calls
communication between base modules and the administrative modules
clock distribution and network synchronization.
For this function, a central module has space switch, space switch controller
and a central message switch.
CM provides connectivity to BMs if it is CM-L and 32BMs if it is CM-XL.
57
Each BM interfaces with CM via two 512 channel parallel buses carry voice
information of 512 terminations of the base modules towards the CM.
In the reverses direction, after space switching has been done in the space
switch under the control of space switch controller (ssc).
58
Same buses carry the switched voice information, for 512 terminations
toward the BM.
Thus in a 32base module configuration, there are 64 parallel buses carrying
the voice information form BM to the CM and also the switched information
in the reverse director.
5.20 Space Switch (ss) Space Switch Controller (ssc):-
In order to take care of the large no. Of interface signals the switch portion
of the CM is divided into three stages. MUX stage, Switch stage and
DEMUX stage. The MUX and DEMUX stages are implemented on single
card to provide the base module to central module interface in each direction.
MUX\DEMUX cards extract the information from time slots 0 and 1 of bus0
and bus 1 from the base module.
The CMS sends this message to the Space Switch controller (ssc) on a 128
kbps links to control space switching based upon this information.
Four 512-channel buses from four BMs are multiplexed to form a 2048
channel, 16 mbps multiplexed BUS, which is since to both copies of the
space switch card.
5.21 CLOCK DISTRIBUTION:-
CM provides the central clock for distribution to the base modules. The 8MHz clock may be locally generated at the Central Clock (CCK) card in case CM-XL and of space switch Clock (SCK) card in case of CM-L by using high stability VCXO crystal or may be derived from an external reference clock using the Network Synchronization Equipment (NSC) card in case of CM-L under the control of SSS.
The CBX card provides an interface between SSC and SSU. SSC makes any switch card access through CBX.
5.22 CENTRAL MESSAGE SWITH (CMS):-
59
CMS Complex is the central message transfer point of the switch. It is implemented as four different message switches working in load – sharing mode.
Each message switch is a high performance message routing block, implemented by using high-speed 32-bit microprocessor MC 68040 in case of CM-Xl and 16-bit microprocessor MC 68000 in case of CM-L.
ALL CMS (CMS 1,2,3&4) are used for routing of messages across the BM. This communication is used to access office data for routing inter-module
calls and Administration and maintenance function.
5.23 ADMINISTATIVE MODULE (AM):-
AM consists of a duplicated 16/32-bit controller celled the administrative processor (APC).
It communicates with Base processors via the CMS for control messages and with the duplicated IOPs in the IOM for interfacing peripheral devices.
Administrative processor is responsible for global routing, translation, resource allocation and all other function that are provided centrally in C-DOS DSS MAX.
The implementation of AM is similar to BPC of BM , using the same hardware configuration.
5.24 INPUT OUT PUT MODULE (IOM):-
Input output Module (IOM) consists of duplicated Input Output Processor (IOM).
The Input Output Processor (IOP) is a general-purpose computer with UNIX operating System. It is used as the front-end processor on C-DOT DSS. It handles all the input and output function in C-DOT DSS.
The IOP is connected to AP/BP via HDLC links. During normal operation, tow IOPs interconnected by a HDLC link, operate
in a duplex configuration. Working as ront-end processor, it provided initial code down load to the subsystem, man machine interface and data storage for billing and other administrative information.
5.25 REMOTE SWITCH UNIT (RSU):-
60
It is an integral part of C-DOT DSS architecture. To realize a RSU, the normal BM can be modified for removing with the host exchange via 2-Mbps digital links.
RUS is an autonomous exchange capable of local cal complication. Operating and maintenance function are handles by the host exchange. In the event of failure of PCM link, RSU goes into stand-alone mode of operation, the local and incoming terminating calls in RSU are switched and the metering information of the entire RSU subscriber is stored in the RSU.
Only the even numbered BMs can be configured. as RSU. That is a
maximum 16 RSUs are possible in MAX-XL and 8 RSUs in MAX-L
In RSU the TSS cards in BM are replaced by ETS (Enhanced Time Switch)
cards. This card implements different function like:
HDB3 to NRZ conversion.
Clock extraction .
Time slot interchange on PCM links.
Digital trunk interface .
Fault handling on digital trunks.
5.26 ALARM DISPLAY PANEL (ADP):-
It is a microprocessor based hardware unit. which is attached to BP (in SBM)
or AP (in MBM ) via HDLC link for providing audio-visual indication of
system faults.
It is a three-card implementation. A matrix of LEDs is provided of indicate
the maintenance status of the switch units and their level of initialization.
5.27 NETWORK SYNCHRONIZATION IN C-DOTDSS:-
Three modes of operations are :
5.27.1 Locked Mode:-
When one or more primary reference clocks are available NSC/NCE
enters into locked mode by selecting one of the available network clocks
according to fixed priority and synchronizes to it.
5.27.2 HOLDOVER MODE:-
61
When NSC/NSE loses the network clock to which it was locked and
when no other network clocks are available, it enters he holdover mode in which
it synchronizes to the last reference value.
5.27.3 FREE RUN MODE :-
When none of the network reference clocks are available and locking to
external reference has taken place before. In this mode system works on its local
clock.
5.28 FUNCTIONS OF NSC CARD:-
The NSC card format the interface between DTS and the CCKs. It receives
the 2.048 MHz reference input clock from DTS and converts it into a 16.384
MHz clock using a PLL (PHASE LOCKED LOOP). This clock is fed to both
copies of CCKs. It also generates a sine signal (8 KHz) and feds it the CCKs
for further distribution to all the BMs.
There is a Time- OF Day (TOD) block. Which generates real time clock for
the system. It taken the input from DTS card in future (PLL clock) and
embeds this in the 8 KHz sync.
The NSC has an On Board Micro Processor (OBMP) to take care the PLL
functions. Diagnostics and communication with SCC.
5.29 DIFFERENT CASES OF CALL SETUP:-
5.29.1 IN BM 1:-
5.29.1.1 LOCAL CALLS SETUP:-
ORIGINATION:-
Sub ‘a’ lifts handset
SPC cards scans the line port
SPC- TIC senses the origination. TIC forms the origination message.
TIC sends this message to base processor controller through these cards TIC-
TSC-SCIC-BMS-BP (on nailed time slot zero )
BP checks the free/busy status of line port. If free then makes,’ busy’.
5.29.1.2 TIME SLOT ALLOCATION:
62
BP allocate free time slot TIC. i.e. TU to TS (1/28 time slots) toward TU.
BP sends message to MFC/TAG to fed dial tone through these card TGA-
SCIC-TSC-TIC.
5.29.1.3 DIAL TONE:
Subscriber ‘A’ gets dial tone via TGA-SCIC-TSC-TIC-SUB (A).
5.29.1.4 DIGITS DIALING:
MF card collects digit from DTMF subscribers.
For decades subscriber- TIC will collect & send digits to ‘BP’.
Digits are sent message and collect by BP on nailed zero time slot via LCC-
SPC-SCIC-BMS-BP.
Digit analysis is done by ‘BP’.
5.29.1.5 ROUNTING:
BP releases ‘DTMI’ receiver in case of DTMF dialing
Sends routing request message to ‘AP’ via BP-BMS-SCIC-TSC-SSM-SMS-
(a/b)-APU
Digits
Valuing subs category
5.29.2 IN CM:-
5.29.2.1 PATH REQUEST:
‘AP’ checks the inter BM call or intra BM call
Sends path request message to SSC via AP-CMS(A or B)-SSC
Source BM ‘ID’
Called subs ‘B’
Call request
5.29.2.2 CALL REQUEST:
63
SSC checks and allocate a free speech time slot between 2bms
SSC sends message to BP of destination BM via cards.
SSC-CMS (C/D)-SSM-TSC-BMS-BPB
5.29.3 IN BM2:-
CASE-1 : called party free (local call)
5.29.3.1 ‘B’ FREE:
BP of destination BM checks for ‘B’ free form busy/free status of lire port.
Sends message to source BM with parameter
Metering class
Free time slot
Message is routed via these cards.
BPB-BMSB-SCICB-TSCB-SSM-CMS-SSM-TSCA-SCICA-BMSA-BPA
5.29.3.2 RING:
Destination BP sends message for feeding ring to sub B
Ring is fed on line port via SPCB-LCC-sub (B)
5.29.3.3 RBT:
BP sends message to TSC to sent RBT by switching RBT to calling port
(Subs A)
RBT is switched through TGAB-SCICB-TSCB-ESM-PASS-SSM-TSCA-
TICA-sub(A)
5.29.3.4 ANSWER:
Sub ‘A’ is getting RBT & Sub ‘B’ is ringing
Subscriber ‘B’ answers detected by SPC card of base module TCC-SPC-TIC-
TSC-SCIC-BMS-BP
Destination BM (BM2) sends answer message to origination
BM (BM1) via BPB-BMS-SCIC-TSC-SSM-SMS-SSM-TSC-SSC-BMS-BP
(A)
5.29.3.5 CONVERSATION:
Destination ‘BP’ sends message to TSC to operate voice path.
64
The voice path is connected bi-directionally sub a & b.
Subscriber goes into conversation.
5.29.3.6 DISCONNECT:
A party goes on hook SPC senses as disconnection
TIC sends disconnection message to via TIC-TSC-SCIC-BMS-BP
5.29.3.7 CLEAR FORWARD:
Source BP sends clear forward message to destination BP via BPA-BMS-
SCIC-TSC-SSM-CMSA-SSM-TSC-SCIC-BMS-SPB
Sub A is made free
5.29.3.8 RELEASE PATH:
Source BP sends message for release path to SSC via.
BP-BMS-SCIC-TSC-SS,-SMS-SSC
SSC release the conversation path
5.29.3.9 METERING:-
Source BP undated meter count of sub ‘A’
For detail bill-sends message to ‘AP’
5.29.3.10 PARKING TONE:
On receiving ‘clear forward’ message form source BM destination. BM feeds
parking tone to sub B via TGA-SCIC-TSC-TIC SUB (B)
B Party goes on hook
SPC senses clear back. B is made free
Call is disconnected.
CASE-2 : CALLED PARTY BUSY (LOCAL CALL)
5.29.3.11 ‘B’ BUSY:
65
BP of destination BM checks for ‘B’ busy/free status of line port.
sends message UFAIL 02 to SSC and sources BP fail type (busy)
Message is routed via these cards.
SSC release the path.
5.29.3.12 BUSY TONE:
Source BP connect busy tone sub ‘A’
The busy tone is fed via TGA-SCIC-TSC-TIC-sub (A)
5.29.3.13 DISCONNECTS:
A party goes on hook-SPC senses as disconnection
TIC send clear forward message to BP via TIC-TSC-SCIC-B<SBP
Sub-A is made free.
5.29.4 OUTGOING CALL SETUP:-
5.29.4.1 IN. BM1
5.29.4.1.1 Origination:
SPC card scans the line port
SPC-TIC senses this message to base processor controlled through these
card.
TIC-TSC-SCIC-BMS-BP (no nailed time slot)
BP checks the free/busy status of the line port. If free then makes ‘busy’.
5.29.4.1.2 Time Slot Allocation:
BP allocates free time slot towards TIC i.e. TU TO TS (A/128 time slots)
towards TU.
BP sends message of MFC/TAG to feed tone-through these cards TGA-
SCIC-TSC-SUB (A)
5.29.4.1.3 Dial Tone:
Subscriber ‘A’ gets tone via
66
TGA-SCIC-TCS-SUB (A)
5.29.4.1.4 Digits Dialing:
MF card collect digits for DTMF subscriber.
For decoding subscriber –TIC will collect & send digit to ‘BP’
Digits are sent as message and collected by BP on nailed zero time slot via
LCC-SPSPC-TIC-BMS-BP
Digits analysis is done by ‘BP’
On receiving some digits call routing tone is connected to ‘A’ party.
5.29.4.1.5 Routing
BP release ‘DTMF’ receiver in case of DTMF dialing
Sends routing request message to ‘AP’ via
BP-BMS-SCIC-TSC-CMS (A/B) = APU
DIGITS
Calling subs category.
5.29.4.2 IN CM:-
5.29.4.2.1 Path Request:
Source BM ‘ID’ a. ‘AP’ checks for trunk call allocate the trunk group number
Sends path request message to SSC via
AP-CMS (A/B)-SSC
Destination BM ‘ID’
Trunk group number
5.29.4.2.2 Call Request:
SSC checks & allocate a free speech time slot between two BM.
SSC sends message to BP of destination BM via these cards.
SSC-CMS (C/D)-SSM-TSC-SCIC-BMS-BPB
BP of trunk BM allocates a free trunk of that trunk of that group from
busy/free status ports.
5.29.4.3 IN BM:-
5.29.4.3.1 Seize Forward:
67
BP of destination BM asks TIC to send seizure on o/g trunk.
If this is OGMF call then MF sends is connected with this trunk for MF
signaling
CASE-1: CALLED PARTY FREE (O/G/ Call)
5.29.4.3.2 Seized Forward:
MFC/TIC outputs the digits (Starting from ROD)
The other exchange informs the sub free signal on MF Signaling.
MF sender is released.
5.29.4.3.3 Ring Back Tone:
The other exchange sends ringing to sub ‘B’
Ring back tone is given to ‘A’ party on conversion path through other
exchange.
5.29.4.3.4 Answer:
Sub ‘A’ getting RBT & sub ‘B’ is ringing.
Subscriber ‘B’ answer – detected by SPC card ot base
Module via TWT-SPC-TSC-SCIC-BMS-BP AS LINE SIGNAL .
THROUGH SPC & TIC card
Now destination BM send answer message to origination BM vib BPB-BMS-
SCIC-TSC-SSM-TSC-SCIC-BMS-BP(A)
5.29.4.3.5 Conversation:
A party goes on hook-SPC senses as disconnection
TIC sends disconnection message to BP via
TIC-TSC-SCIC-BMS-BP(A)
5.29.4.3.6 Disconnect:
A party goes on hook-SPC senses as disconnection
68
TIC sends disconnection message to BP via
TIC-TSC-SCIC-BMS-BP(A)
5.29.4.3.7 Clear Forward:
Source BP sends message for release path to SSB via BP-BMS-SCIC-CMS-
SSC
SSC release the conversation.
5.29.4.3.8 Release Path:-
Source BP sends message for release path to SSB via BP-BMS-SCIC-CMS-
SSC.
SSC release the conversation.
5.29.4.3.9 Metering:
Source BP updates meter count of sub ‘A’
Call is disconnected.
5.29.4.3.10 Parking Tone:
On receiving ‘clear forward’ message from source ‘BM’ destination BM
feeds parking tone to trunk to OG trunk.
Party goes on hook.SCP sense normal on trunk.
Call is disconnected.
CASE-II : CALLED PARTY BUSY (O/G CALL)
5.29.4.3.11 Out Pulsing Digits:
MFS/TIC out pulse the digits (starting from ROD)
The other exchange receives the digits-checks sub ‘B’ is busy informs ‘B’
Condition on MF signaling.
MF sender is received.
5.29.4.3.12 Busy Tone:
MFC passes the signal to trunk BP via MFC-SCIC-BMC-BP
69
BP about the busy signal.
Busy tone is fed to ‘A’ party by source B
MFC-SCIC-TSC-TIC-SUB(B)
MF sender is released.
5.29.4.3.13 Disconnect:
A party goes on hook –S{C senses as disconnection
TIC sends disconnection message to BP via TIC-TSC-SCIC-BMS-BP
SUB ‘a’ made free
5.29.4.3.14 Clear forward:
Source BP send clear forward message to destination BP via
BP-BMS-SCIC-TSC-SSM-CMSA-SSA-TSC-SCIC-BMS-BP
O/G/ TRUNK IS MADE FREE:-
5.29.4.3.15 RELEASE PATH:
Source BP send message for release path to SSC via BP-BMS-SCIC-TSC-SSM-
CMS-SSC
70
6.1 INTRODUCTION:-
Alcatel 1000 E 10 is the digital switching system developed Alcatel CIT.
71
Multi-application, Alcatel 1000 E 10 could be used for the entire range of switch, from the smallest local exchanges to the large transit gateway switches.
It adapts to every type of habitat, form dense urban environment, to sparsely populated areas, and to every type if climate, from Polar Regions to the hot and humid climates of Equatorial Africa and the tropics.
System operation and maintenance can be local or common to several switches, or both at the sane time.
Alcatel 1000 e 10 provides all modern communication services: Basic Telephony, ISDN, Centrex, digital cellular radiotelephony and the all the Intelligent Network applications.
It handles all accepted signaling system in a current total of over 80 countries and is built in accordance with recognized international standards. Alcatel CIT actively contributes to definition of those standards.
6.2 SYSTEM APPLICATIONS (NON-EXHAUSTIVE LIST):-
Remote subscribers unit. Local subscribers exchange. Transit exchange (local, trunk or international gateway). Tandem exchange. Centrex (private or public).
6.3 GLOBAL NETWORK:-
The development of Alcatel 1000 E 10 is a key element in Alcatel’s concept of Global Network offers a complete service for all current and future needs of our customers.
The Alcatel Global Network encompasses the telephone network and its evolution towards ISDN, data and value-added networks.
(Particularly message handling system and video text), intelligent network, cellular radio system, operation and maintenance networks and finally, the evolution broad band ISDN using Asynchronous Transfer Mode (ATM) techniques.
72
Subscriber line with 2, 3 or 4wires. ISDN basic access at 144Kbit/s (2B+D). ISDN primary access at 2Mbit/s (30B+D). Standard PCM (2Mbit/s, 32channels, CCITT G732). Analogue or digital data link with 64Kbit/s or standard PCM. Digital link with 64 Kbit/s (X25 protocol, Q3 interface) or analogue link with
rate of <19.200 bit/s(V24 protocol).
6.4 Calls Handled:-
73
The Alcatel 1000 E 10 handles telephone calls from or the national and International public switched telephone network. It also transfers data between its ISDN subscriber as well as to from the packet switched network.
These calls include:
Local calls (private, public), Regional calls: outgoing, incoming, transit, National calls: outgoing, incoming, transit, International calls: automatic or semiautomatic, outgoing or incoming Manual calls (operator assisted): outgoing, incoming, Outgoing calls to special services, Test calls.
6.5 GENERAL PERFORMANCE DATA:- Performance of any switching system is highly dependent on its environment
(call mix, condition of operation). The capacity given below is for information purpose, based on an average reference environment.
Maximum processing capacity of the system is 280 CA/s, under CCITT B load system (Q 543)-i.e. 1,000,000 BHCA.
The connection capacity of the host-switching matrix ranges up to 2048 PCM, which permits:
Up to 25,000Erlang to be handled (on CCITT B load (Q5433). Up to 200.000 subscriber to be connected, Up to 60,000 circuits to be connected.
6.6 FUNCTIONAL ARCHITECTURE:-
General function architecture The Alcatel E 10 system is located at the heart of the telecommunication
networks concerned. It is made up of three independent function units: The “subscriber access subsystem” which carries out collection of analogue
and digital subscriber lines. “Connection and control” which carries out connections and processing of
calls. “operation and maintenance” which is responsible for all functions needed by
the network operating authority Each functional unit is equipped with soft wares, which are appropriate for
handling the functions for it is responsible.
6.7 OCB 283 FUNCTIONAL ARCHITECTURE:-
74
The OCB 283 consists of:
I. BT (Time Base)II. SMX (Host Switching Matrix)
III. URM (PCM Controller)IV. ETA (Auxiliary Equipment Manager)V. MR (Call Handler)
VI. TR (Translator)VII. TX (Call charging and Traffic Measurement)
VIII. GX (Matrix System Handler)IX. MQ (Massage Distributor)X. OM(Operation and maintenance Function)
The above block diagram shows the functional block diagram of OCB 283. Il shows the block that are given as below:
75
Time base (BT): The BT ensures times distribution for LR and PCM to provide the synchronization, and also for working out the exchange clock.
Host switching matrix (SMX): The SMX is a square connection matrix with a single time stage, T, duplicated in full, which enables up to 2048 matrix links (LR) to be connected.
A matrix link LR is internal PCM, with 16 bits per channel (32 channels). Additional 8 bits for redundancy & call control, parity7 check, branch control.
COM+MCX=SMX
The MCX can execute the following: A unidirectional connection between any incoming channel any outgoing
channel. There can be any simultaneous connections as there are outgoing channels.
Connection between any incoming & any M (Broad Cast) outgoing channels. Connection of N incoming channels belonging to one frame structure of any
multiplex onto N outgoing channels which belong to. He same frame structure, abiding to the integrity & sequencing of the frame
received. The MCX is controlled by the COM function (matrix switch controller) to
ensure the: Set up & break down of the connection access is used to the matrix command
memory. This access is used to write at output T.S. address the incoming T.S. address.
Defense of the connections. Security of the connection in the order to the promise a good data switching.
6.8 PCM CONTROLLER (URM):-
The PCM provided the interface between external PCMs & the OCB-283.
These PCM come from either:
A remote subscriber digital access unit (CSN) or from a remote electronic satellite concentrator CSE,
Another switching center, on channel- associated signaling or CCITT No.7, The digital recorded announcement equipment.
In particular, the UMR carries out the following functions:
HDB3 conversion to binary (PCM->matrix link ),
76
Binary conversion to HDB3 (matrix link -> PCM) Extraction and pre-processing of the channel-associated signaling T.S16
(PCM-> command). Transmission of channel associated singling in T.S16 (command PCM).
6.9 AUXILIARY EQUIPMENT MANAGER (ETA):-
The ETA supports:
The tone generators (GT) The frequency receiving and generator (RGF) devices, Conference circuits (CCF), The exchange clock. CCS7 protocol hander (PUPE) and CCS7 controller (PC): CCITT no.7
protocol processing.
More precisely, the PURE function carries out the following:
“Signaling channel” level 2 processing,
77
The “message routing” function part of level 3 .
The PC carries out:
The “network management” function (part of level 3). PURE defense, Various observation tasks which are not directly linked to CCITT No.7.
6.10 Call handler (MR):-
The MR is the responsible for the establishment and braking off of communication.
The call handler takes the decisions necessary for processing of communication in term of the signaling received, after consultation of the subscriber and analysis database manager (TR) if necessary ,
The call handler processors new calls handling-up operation, releases equipment, commands switching on and switching off etc.
Subscriber and analysis database manager (TR) (TRANSLATOR).
The TR supplies the call handler, on request from it, with subscriber and circuit characteristics necessary for establishing and breaking off communications.
The TR also ensure match between the dialing received and the address of circuit groups or subscribers.
6.11 Call charging and traffic measurement:-
The TX function carries out charging for communications.
TX is responsible for: Calculating the amount to be charged for each communication, Keeping the charge account of each subscriber served by the switching
center, Supplying the necessary information for drawing up detailed billing, on line
to the OM.
6.12 Matrix system handler (GX):-
78
The GX function is responsible for processing and for defense of connections on receipt of:
Request for connection or disconnection coming from call handler (MR) or message distributor functions (MQ).
Connection faults signaling by the matrix switch controller function (COM). The GM carries out monitoring of certain links of the connection central
subsystem periodically or on request from certain links.
6.13 Message distributor:-
The MQ function is responsible for distribution and formatting of certain internal message but, above all, it carries out.
Supervision of semi-permanent connection(“data links”), Transmission of message between the communication multiplexes
(“gateway“) function.
6.14 Communication multiplex:-
One to five communication multiplexers are used to transmit messages from one station to another.
This transfer of message is carried out by only one type of medium, the TOKEN RING, with unique protocol, which is processed in according with IEEE 802.5 standard.
6.15 Single multiplex (Compact configuration):-
It is then referred to as the insertion Multiplex (MIS). More than one specialist Multiplex: Linter station multiplex (MIS) for interchanges message between the
command functions and operation and maintenance software, From 1 to 4 stations access multiplexes (MASs) for interchanges message
between the connection functions (URM, COM, ETA, PURE) and the command functions.
6.16 Operation and maintenance function:-
The functions of the operation and maintenance subsystem are carried out by the operation and maintain software (OM).
The operating authority accesses all hardware and software equipment of the Alcatel 1000 E 10 system via computer terminal belonging to the operation and maintenance subsystem: consoles, magnetic media, and intelligent terminal.
These functions can be grouped into 2 categories:
Operation of the telephone application, Operation and maintenance of the system.
In addition, the operation and maintenance subsystem carries out:
79
Loading of software’s and of data for connection and command and for the subscriber digital access units,
Temporary backup of detailed information, Centralization of alarm data coming from connection and control stations, via
alarm rings, Central defense of the system. The operation and maintenance subsystem permits two-way communication
with operation and maintenance network at regional or national level (TMN).
6.17 ROLE OF THE SWITCHING MATRIX SYSTEM (CCX):-
The switching matrix system is establishes interconnections of time- domain channels for local subscriber Digital Access units (CSNLs) and the Trunk Control and Auxiliary Equipment Control stations.
In general, the Switching Matrix System carries out:
Unidirectional connection between any incoming channel and any outgoing channels.
Connection between any incoming channel and any M outgoing channels. “N#64 kbps connection” that is connection of N incoming channels to the N
outgoing channels which belong to the same frame structure. Switching between auxiliary equipment and speech channels for voice
frequencies signaling operations. Simultaneous distribution of tones and recorded announcements. Permanent switching of channels.
80
81
Station Functions Numbers
SMC MR 2to7
SMC TX 2
SMC MR,TR 2
SMC MR,DX 2
SMC TR,MQ,PC 2
SMC MQ,GX,PC 2
SMC MQ,GXTR,TX,PC 2
SMC MR,MQ,GX,TR,TX,PC 2
SMA ETA 2 to 31
SMA PURE 2 to15
SMA ETA,PURE 2 to15
SMT URM 1 to 28
SMX COM 1 to 8
SMM OC,OM 1
FIG. MAXIMUM AND MINIMUM MODULES FOR STATIONS
82
6.18 ROLE OF TRUNK CONTROL STATION (SMT):-
The Trunk Control Station ensures functional interface between the PCM and the switching Center.
The PCM come from:
Another switching center, A Remote Electronic Satellite Concentrator (CSED), A Remote Subscriber Digital Access Unit(CSND), The digital recorded announcement equipment.
The Trunk Control Station (SMT) permits implementation of the PCM controller “URM” (multiplex connection unit) function that mainly consists of Two Part:-
6.18.1 In PCM to switching center direction:
HDB3 conversion to binary, Extraction of channel associated signaling, Management of semaphore channels carried by TS16, Cross-connection of channels between PCM & matrix link (LP).
6.18.2 In switching center to PCM direction:
Binary to HDB# conversion, Transmission of channel associated signaling, Management of semaphore channels carried by TS16, Cross connection channels between matrix link and PCM.
83
7.1 INTRODUCTION:-
It means Cor DIGITAL ENHANCED CORDLESS TELECOMMUNICTION.
The telecommunication system today, consists of:- 1. Access network.2. Backbone network.
7.1.1 Access Network:-
The access network is consists of Remote Line Unit (RLU)/Remote Switching Unit (RSU) and local loop. The RLUs/RSUs are connected to the main exchanges using E1 lines and are located nearer to the subscriber. The local loop is mostly twisted pair copper wire design to carry 4 KHz signal.
84
7.1.2 Backbone Network:-
The backbone network includes trunks, inter-connecting exchanges, and long distance trunks, inter-connecting exchanges in different cities. Over the last two decades, the trunk network has been largely digitized and carries time division multiplexed PCM voice. The medium used is mostly optical fiber, and some times radio. E1 comm. At 2.048 Mbps is the basic building block for such a trunk network, though the optical fiber today mostly carries E3, E4 or SDH signals at 34Mbps, 140Mbps and 155Mbps. The backbone network also consists of main exchange and trunk exchanges, which are increasing becoming digital.
7.2 WLL (Wireless in Local Loop):-
The requirement of WLL is diverse. In some highly dense areas, several thousand telephone per sq. km. is required on the other hand spares rural areas less than 1 telephone for 10 sq. km. may required for these telephones; and as the investment made today on installing a telephone is expected to provide service for the next 15 years, the data comm. At a reasonable bit rate a must. While 28.8 Kbps may be acceptable today, these telephones must be upgradeable to 64 Kbps in the next year or two. Further, in these telephone sharing societies.
Where telephone is invariably shared by several people, the traffic handling capability of these lines must be reasonable high [0.1 Erlanger (the traffic is
85
Measured in Erlanger. Generally 1 junction having 0.7 Erlanger handling capacity) per subscriber to 0.15 Erlanger per subscriber].
Measured in Erlanger. Generally 1 junction having 0.7 Erlanger handling capacity) per subscriber to 0.15 Erlanger per subscriber].
WLL is the cost-effective than wired telephone. Thus, these are requirement that CorDECT WLL intend to fulfill.
7.3 BASIC STANDARD OF THE DECT:-
CorDECT WLL system is based on Digital Enhanced Cordless Telecommunications (DECT) standard of European Telecommunications Standards Institute (ETSI). DECT defines a wireless communication standard between a fixed Part (FP) and Portable Part (PP). The communication takes place using Gaussian Frequency Shift Keying (GFSK) Modulation. The access technique used is Multi Carrier Time Division Multiple Access (MC-TDMA), a mess technique, in which frequency can change from one time slot to another.
DECT uses a frame of 10 Micro-Sec in which 24-time slot6 ate defined. The communication between FP and PP uses time division duplex in which 12 times slots are used for each way transmission. In 20 MHz frequency spectrum used by a DECT system, 10 carriers can be used in each of the 12 time-slots, amounting to 120 channels to communication to a FP using Dynamic Channel Selection (DCS) algorithm. The algorithm requires the PP to measure Receive Signal Strength (RSSI) on the 120 channels. It locks to the CBS providing strongest signal and then maintains a RSSI table for all other channels.
ETSI has chosen 1880-1935 MHz band for DECT operation. Normally any 20 MHz band out of this spectrum can be chosen for operation. Each DECT channels can carry 32 Kbps of payload, and the voice coding used in DECT
86
is 32 Kbps ADPCM. It is possible for two DECT channels to be combined to provide 64 Kbps data communication between PP and FP.
CorDECT uses DECT Interface Unit (DIU) and Compact Base Station (CBS) to implement DECT Fixed Part and a wall set to implement DECT Portable part.
7.4 NETWORK INTERFACING TO CorDECT:-
The CorDECT system has been designed such that it could be easily integrated into any country’s network. The system interfaces to the network on E1 (2.048Mbps) lines as peer ITU-T G703 standard. In one the configuration, the CorDECT system acts like as a switch with its local loop. The numbering plan is flexible so that it can be modified as per the requirements.
The tones, announcements, metering, charging, switching, routing and special services are provided by the switch part of the CorDECT system. Alternatively the CorDECT WLL can be configured as an access a network connected to main exchange on ITU-T specified access protocol V5.2.
The CorDECT WLL has been designed to be a modular system. The basic unit provides services to 1000 subscribers. Multiple CorDECT system can be connected together using a transit switch. The CorDECT WLL system does not require frequency planning.
Thus, the low cost make the system one of the most versatile WLL system available today is CorDECT WLL.
7.5 SYSTEM ARCHITTECTURE (CorDECT):-
The CorDECT has 8 major subsystems:-
7.5.1 DIC (DECT Interface Unit):
Perform switching, system control and interfaces CorDECT WLL system to Telephone network.
7.5.2 CBS (Compact Base Station):
87
Provides wireless access in an area and supports 12 simultaneous full duplex channels.
7.5.3 FRS (Fixed Remote Station):-
A wireless fixed terminals, connected to any standard telephone, modem or fax machine and/or to a personal computer.
I.
7.5.4 MWS (Multi Wall Set):
Wireless fixed terminal, providing four independent (telephone, fax, modem) connection in a building.
7.5.5 BSD (Base Station Distributor):
Connects 4 remotely located CBSs to the DIU using an E1 link on radio/fiber.
7.5.6 RBS (Relay Base Station):
A relay device to extend the CBS wireless coverage to 25km.
7.5.7 NMS (Network management System):
88
Manages multiple DIUs and their associated CBS, wall set, multi wallets, BSDs and RBS.
The no. of CBSs and subscriber terminals supported by the system depends on the configuration.
The DIU acts as a switch or remote switching unit, connected to E1 lines using R2-MF or V5.2 protocols. Individual CBS can be connected to the DIU using three pairs of twisted copper wires. The power required for the CBS operation is fed on the same cable from the DIU.
Each isolated CBS can serve about 50 subscribers at 0.1 Erlanger per subscriber.
Employing BSD can connect a group of CBS. Each BSD can support 4 CBS. BSD has to be locally powered and BSD in turn power the CBS.
It is possible to program the well set in special “Distance compensation” mode that allows it to be used up 10km. from a CBS with a line of sight link. Using Relay Base Station (RBS), the coverage area of a CorDECT WLL system can be extended to 25 km. to serve subscribers in sparsely populated areas.
A set of multiple DIUs can managed from the NMS designed for the CorDECT system. Various options are available for the connecting this DIUs to the NMS including LAN, WAN, dial-up connections etc. NMS allows subscriber management, billing and all fault management to be conducted centrally.
7.5.8 DECT Interface Unit (DIU):-
The DIU is a DECT exchange for wireless subscriber and provides an interface to Public Switch Telephone Network (PSTN).
7.5.8.1 Functions:-
89
Call processing CBS powering PCM or ADPCM Transco ding DECT network layer and link layer functions. System operation and maintenance (OMC). Remote fault monitoring
The interface to the PSTN is via E1 digit links interfaces for connecting up to E1 lines are providing. With 4 E1 lines the system can typically cater to about 1000 subscriber with 0.1 Erlanger per subscriber and a grade of service of 1 percentage.
For 1000 wireless subscribers, the DIU can be configured as:
An exchange with R2-MF signaling on E1 lines, or An access network (AM) to an exchange using V5.2 protocol on E1 lines.
The DIU consists of 3 standard 19 sub racks in one cabinet. The system is powered by -48v supply.
7.6 The functions perform by various card/units are as follows:-
76.1 CLOCK CARD (CLCK):-
It provides the required to the whole system. It derives the clocks using the 20MHz, 1ppm TCXO. The clock card synchronizes the system clock to 8 KHz signal receives from the E1 lines from the network via PIMC cards. It can also synchronize to an external 10 m-sec DECT synchronization signal.
7.6.2 SWITCH CARD (SWCH):-
The switch card contains a DSP for the DECT protocol processing and a time switch module. The stream come from CLCK, BUIC, BIMC, TOCON, MONC and OSIF card and contains both voice as well as signaling data. The signaling slots are switch to the on board DSP for processing and this DSP controls the switching matrix.
7.6.3 BIMC CARD (BAES INTERFACE MODULE CEPT):-
This card provides an E1 (G703) interface between the DIC and the BSD. The BIMC card replaces BUIC cards in the DIU back plane.
7.6.4 BUIC CARD (PSTN INTERFACE MUDULE CEPT):-
90
This card provides a G703 interface (E1) to the DIU. It also carries out PCM-ADPCM conversation and echo cancellation on the 30 voice signals carried on the E1 line before passing it on to the switch card on a PCM line. It also handles the R2MF signaling protocol or V5.2 signaling protocol on E1 interface.
7.6.5 TOCON (TONE & CONFERENCE):-
This card provides the necessary tones announcement to be fed to the wireless/wired subscriber as well as to calling party on trunk lines. This card also provides three party conferencing. There are 2 TOCN cards in a system.
7.6.6 OSIF CARD:-
This card is a PCI bus add-on card to OMC-PC and provides a PCM interface to the SWCH card using RS422 electrical signal.
7.6.7 SYSTEM CONTROLLER (OMC-PC):-
OMC-PC acts as system controller for DIU. This system carries out processing, OMC function, administration functions and network management functions. The system controller also provides an interface to a printer and data back-up device.
7.6.8 PWR MODULE (POWER MODULE):-
This module supplies power to the whole of DIU, except the system control. It takes -38v DC as input and generates 5v supply required by the entire card.
7.7 DIU FEATURES:-
System auto-configuration. Security. Subscription related database. Billing. System health monitoring. Traffic analysis. Network management system Tones supported. Announcements. Three party conference calling.
7.8 CBS (Compact Bade Station):-
91
The CBS is a small, unobtrusive pole mounted unit. Each CBS serves one call, providing up to 12 simultaneous speech channels. The radius depends on the propagation environment and antenna gain of the wall set. Typically it ranges from 150km-10km.
The CBS has 2 antennas for diversity. A direction antenna with significant gain can be used when coverage area is divided into sectors covered by different CBSs. Otherwise an Omni directional antenna could be used. Such Omni direction antennas with 6dB and 9dB gains are available.
The CBS is interface to the Diu using three standard subscriber pairs from the existing pool plant. Typically this would be from the reliable buried. (To implement under ground directly) portion of the loop plant terminating at the distribution points.
The 3 pairs carry four ADPCM speech channels each in addition to signaling data, on 2B+D format of N-isdn communication.
The pairs also supply power to the CBS from the DIU. The maximum distance between CBS and DIU is 3.5 km with 0.5mm
diameter copper twisted pairs. Alternatively, the CBSs are interface to the DIU through the Base Station
Distributor (BSD) unit as shown in fig. The maximum distance between CBS and BSD is 1 km. when 0.5mm twisted
pair copper cable is used.
7.9 Functional Description:-
7.9.1 THE LINE INTERFACE/POWER SUPPALY MODULE (LIPS):-
This module is the front-end module interlinking the CBS to DIU. It derives power from the three twisted pair wires coming to the CBS and provides the power supply for the CBS.
The DC-DC converter used can take in voltage in range of 48VDC to 120VDC & generates required voltage for internal operation.
The card also has discharge tubes and fuses for protection on each of the4 three lines.
Besides, the LIPS cards also provides interface for the 160160Kbps digital signal between BBP & each pair of twisted pair wire.
7.9.2 THE BASEBAHD PROCESSOR (BBP):-
This module holds two blocks, each controlled by a processor.
92
The DIU interface module provides the wire line connectivity and operates at 5V.
Inter-processor communication between the two blocks is through a synchronous serial bus with appropriate level translation.
7.9.3 DIU INTERFACE MODULE (DIM):-
The DIU interface module implements the following functions:-
Data transfer between the DIU and the air interface. DECT protocol stacks. Synchronizations of the CBS to the DIU.
7.9.4 AIR INTERFACE MODULE (AIM):-
The air interface module implements the following functions:
Provides all necessary control/timing functions for a 12 slot, non-blind air interface.
Synchronization DECT data transfer between the air interface and DIM controller. Modem. Scrambling and encryption.
7.9.5 THE RADIO TRANS-RECEIVER SECTION:
The radio trans-receiver consists of two identical radios. Each radio is made active in every alternate slot, and taken together; implement a non-blind slot air interface
The two radio modules are mounted under the BBP. The RF signal from each radio is carried an antenna switch. Each radio
module contains the receive and transmit chains, a receive-transmit antenna switch and PLL synthesizer. All control lines for the receiver transmitter and synthesizers are provided by the BBIs.
7.9.6 CBS ARCHITECTURE:-
The block diagram for CBS is shown in figure. The RF module is designed so that the CBS can operate on the 12slots and has a fully DECT complaint air interface.
It supports two antennas and provides antenna diversity for improved coverage.
93
The Base Band Section consists of two DSPs. The Base band interface DSP carries out modulation, framing, encryption and scrambling as defined in DECT specifications.
The line interface section derives power, either from a local supply or the power fed in the three pairs of twisted pair wires.
7.9.7 Erlang Traffic Handling Capability Of CBSs:-
A CorDECT CBS can operate on 12 channels on the air. Thus an isolated CBS can provide service to subscribers on 12 channels, amounting to Erlang traffic at 1.0% grade of service.
94
The CBS can therefore serve either 70 subscribers at 0.07 Erlang per subscriber or 35 subscribers at 0.15 Erlang per subscriber.
Thus, two CBS can support 24 channels or 15 Erlang at 1.0%grade of service i.e. 150 subscribers at 0.1 Erlang per subscriber can be supported.
If two CBSs have totally overlapping coverage, a wallets/handset in the coverage area could communicate on any of the 24 channels offered by the two CBS.
Therefore each CBS supports one and half times the number of subscribers supported by an isolated CBS.
7.9.8 BSD (Base Station Distributor):-
The Base Station Distributor is an optical unit when clusters of CBSs are to be located some distance away from the DIU.
The BSD is connected to the DIU on E1 lines and each E1 lines carries signals for four CBSs.
The BSD De-multiplexers the signal on the lines and feeds it to four CBSs. The four CBSs are connected to the BSD, each using three pairs of 0.5mm
twisted pair copper wires. The maximum distance supported is 1 km. the copper wires carry both power and signals from BSD to CBS.
7.9.9 FRS (Fixed Remote Station):
The FRS is a small wall mounted unit with an external antenna and power from a/c mains. An internal battery provides back up in case of power failure.
The external antenna provides gain and range of a CBS in area where CBS density is low.
The data rate support on modem is typically 9600 kbps as the voice is coded (32 kbps ADPCM), before transmission on air.
The FRS has:
Antennas Line Data Module (ALP) Customer Premises Module (CPM)
7.9.10 MWS (Multi-Wall set):
To cater to multiple subscribers at the same geographical location, e.g. an office or apartment block, a multi-wall set can be used.
This unit supports up to four subscribers there by substantially reducing cost per subscribers. The multi-wall set provides each subscriber an independent line.
MWS is a fixed, mains power system with external high gain antenna, for extended range and supports four subscribers.
The MWS has:
95
A DECT Trans receiver Module (DTM) A Subscriber Interface Module (SIM)
The DTM provides an ETSI complaint air-interface for CBS-MWS communication.
The SIM provides four 2-wire telephone interfaces.
7.9.11 RBS (Relay Base Station):
The RBS comprises of two units, namely the RBS Air Unit (ARU) and RBS ground unit (GRU). Both units are housed in sealed weatherproof enclosures suitable for outdoor mounting.
The ARU contains the DECT base band and RF electronics, with antenna interface to the CBS and wall sets.
The GRU houses the power supply electronics and the maintenance controller.
96
The ARU and GRU are connected thorough a 10-core cable.
7.9.12 Flexibility and Reliability:-
CorDECT system design is flexible so that it can cost effectively deployed in different scenarios and provide services with high reliability.
The overall MTBF for the CorDECT system is design such that the system gives satisfactory performance as long as the BER (Bit Error Rate) of the radio link is better than 10^-3.
The ADPCM voice coding gives fairly high quality voice at this BER. High Bit Rate data communication in DECT is supposed to use error coding ARQ to ensure the desirable bit error rate.
7.10 SYSTEM APPLICATON CONFIGURATION:-
The CorDECT system connected to the PSTN in following three modes:-
7.10.1 Digital Trunk mode:
In this configuration, the DIU acts as an independent terminal exchange cum base station controller.
The DIU is connected to the PSTN using E1 trunks. The signaling protocol between the DIU and the PSTN is R2-MF.
97
This allows channel associated signaling for incoming and outgoing calls of subscriber registered with the DIU.
7.10.2 RLU MODE:
In this configuration, the DIU acts purely as the access interface and all call handling function as well as billing support functions are carried out by the PSTN exchange.
CorDECT system can connected to the PSTN exchange using V5.2 protocol of ETSI (European Telecommunications Standard Institute) on E1 lines.
7.10.3 ITOS (INCOMING TRUNKS-OUTGOING SUBSCRIBER) MODE:-
This is an unconventional mode of PSTN interconnection, which is useful whenever the two modes described above are not feasible. In this configuration, the DIU is interfaced to the PSTN different for incoming and outgoing calls.
E1 trunk lines with R2-MF connect DIU directly to E1 ports. Though a multiplexer to two wire trunk ports.
98
7.11 TRAFFIC MEASUREMENT AND REPORTS:-
7.11.1 Exchange or Base Station Traffic Measurements:
Total call attempts Successful attempts No dialing attempts Incoming attempts Calls failed in other states Abnormal releases Failures due to congestion
7.11.2 Trunk Traffic Measurements:-
Total call attempts Successful attempts Operator attempted calls Failure due to congestion Congestion times and durations
7.12 TECHNICAL SPECIFICATION:-
RF CHANNEL FREQ. BAND 1880-1900 MHZ(FACTORY SET) 1900-1920 MHZ/ 1910-1930MHZACCURACY OF CENTER FREQUINCIES +50/-50 KHzTDMA FRAME DURATION 10msecTRANSMISSION BIT RATE 1.152 MBPSTDMA SLOT LENGTH 480 BITSNO. OF SLOTS PER FRAME 24;12 FOR Tax, 12 FOR Rx (TDD)ACCURACY OF BIT CLOCK +25/-25ppm at wall set or handset
+10/-10ppm at base station +5/-5ppm at DIU
MODULATIONL Gaussian freq. Shift KeyingFREQUENCY DAVIATION +288 KHz (nominal) for all ONE bit pattern,
-288 KHz (nominal) for all-ZEROBit rate
TRANSMIT POWER +24 dBm nominal
VOICE CODING ITU-T G726 ADPCMSESITIVITY At -73 dBm, bit error rate<10^-5
At -83 dBm, bit error rate <10^-3
99
100
8.1 INTRODUCTION TO GSM:-
The GSM standard is the first international that gives subscriber full access to the network of various operating companies in all participating countries.
8.1.1 GSM OPERATION REQUIREMENTS:
International roaming. High spectral efficiency. Improved Transmission Quality as compared to Analog system. High Link Integrity. Provision of Tele Services & Bearer Services. Economy in both sparsely and heavily populated areas. Better use of available frequencies in order to improve the capacity or mobile
communications. Large selection of interfaces to other services such as PSTN/ISDN, PSDN
etc.
101
8.1.2 SPECIFICATIONS:-
Trunked Radio System. Access Method-TDMA/FDMA. Frequency Bands. Mobile to cell -890-915MHz (Up Link). Cell to Mobile -935-960MHz (Down Link).
Therefore the frequencies for the uplink and the downlink are different (Frequency Division Duplex) and the bandwidth of the GSM System is 25MHz.
Channel Bandwidth 200 KHz. Number of channels -124 channels pair (25 MHz/200KHz) are available at 200 KHz
intervals.
Due to interference to other systems, the very first carrier is not used.
8.1.3 GSM-MULTIPLE ACCESS:-
102
GSM uses both FDMA & TDMA Total 124 access along frequency axis One or more carrier assign to each base station. Absolute radio frequency carrier number (ARFCN) 1&124 not used until it is
co-coordinated with Non-GSM operation in adjacent frequency bands. in most cases 124 RF channels are used.
8.1.4 FDMA/TDMA:-
Each channel pair serves eight (full rate) or sixteen channels successively in a timed cycles.
In FDMA system each channel requires a transmitter & receiver.
8 voice channels, staggered in time are transmitted via 1 carrier frequency. Each of the 124 FDMA linked carrier freq. is used to transmit 8 TDMA voice
channels. Discontinuous nature of TDMA makes the entire 200KHz bandwidth
available to all channels.
103
8.1.5 MODULATION METHOD(GMSK):-
The modulation method used in GSM is GMSK (Gaussian Minimum Shift Keying).
The GMSK facilitates the use of narrow bandwidth and coherent detection capability.
Rectangular pulses are passed through a Gaussian filter prior to their Passing through a modulator. The modulation scheme almost satisfies the adjacent channel power Spectrum density requirements of -60dB specified by CCIR.
8.2 Overview of GSM Interfaces:-
For the connection of the differ nodes in the GSM network different interfaces are available:-
8.2.1 Air Interfaces or U-m Interfaces:
This is the interface between the BTS(Bases Transceiver Station) and the MS(Mobile Station).
It is required for supporting. Universal use of any compatible mobile station in a GSM network.
104
A maximum spectral efficiency.
8.2.2 A Bits – Interfaces:
This is the interface between the BSC (Base Station Controller) and the BTS. Functions implemented by this interface are Voice-data traffic exchange. Data exchanges between the BSC and the BTS. Transport synchronization information from the BSC to the BTS.
8.2.3 A –Interface:
The A-interface us the interface between the BSC and the MSC (Mobile Switching Center).
8.3 TYPES OF LOGICAL CHANNELS:-
8.3.1 Traffic Channel:-
The traffic channels are used to send the speech or data services.
There are two types of traffic channels:-
1. TCH/F(Traffic Channel Full Rate)2. TCH/H(Traffic channel half rate)
8.3.1.1 TCH/F(Traffic Channel Full Rate):-
The TCH/F carries information at a gross bit rate of 22.8 Kbit/s (after channel coding). The net rate at the TCH/F is for speech 13 Kbit/s and for data 12.6 or 3.6 Kbit/s.
8.3.1.2 TCH/H(Traffic channel half rate):-
The TCH/H carries information at a gross bit rate of 11.4 Kbit/s. The net bit rate at the TCH/h is for speech 5.6 Kbit/s and for data 6 or 3.6
kibitz/s.
8.3.2 Broadcast channels:-
The broadcast channels are points to multipoint channels, which are defined only for downlink (BTS to mobile station).
They Are Divided Into 11 Sub Channels:
105
8.3.2.1 BCCH (Broad cast control channel):-
BCCH act as a beacon. It informs the mobile about system configuration parameters.
Using this information MS choose the best cell to attach to.
8.3.2.2 FCCHC (Frequency correction channel):-
MS must tune to FCCH to listen to BCCH. FCCH transmits a constant frequency of that is used by the MS for
frequency correction.
8.3.2.3 SCH (Synchronization channel):-
SCH is used to synchronize the MS in time SCH carries TDMA frame number and BSIC (Base station identity code).
8.3.2.4 Common control channels:-
Common control channels are specified as point to multipoint, which operate only one direction either in uplink or downlink.
8.3.2.5 PCH (paging channel):-
PCH is used in downlink direction for sending paging message to MS whenever there is incoming call.
8.3.2.6 RACH (Random access channel):-
RACH is used by the MS to request allocation of a specific dedicated control channel (SDCCH) either in response to a paging message or for call origination/registration from the MS.
This is an uplink channel and operates in point to point mode.
8.3.2.7 AGCH (Access grant channel):-
AGCH is a logical control channel, which is used to allocate, specifies dedicated control channel (SDCCH) to MS request for a channel over RACH.
AGCH is used in downlink direction.
8.3.2.8 Dedicated Control Channel:-
Dedicated control channel are full duplex point-to-point channels. They are used for signaling between the BTS and certain MS.
8.3.2.9 SACCH (Slow associated control channel):-
106
The SACCH is a duplex channel, which is always allocated to TCH or SDCCH.
The SACCH is used for radio link supervision measurement, power control and timing advance information.
8.3.2.10 FACCH (Fast associated control channel):-
FACCH is requested in case the requirement of signaling is urgent and signaling requirement cannot be met by SACCH.
During the call FACCH data is transmitted allocated TCH instead of traffic data.
8.3.2.11 SDCCH (Stand alone dedicated control channel ):-
The SDCCH is duplex, point to point channel which used for signaling in higher level.
It carries all the singling between BTS and MS when no TCH is allocated to MS.
8.4 GSM ARCHITECTURE:-
8.4.1 INTRODUCTION:
A GSM system is basically designed as a combination of three major sub systems.
The network sub system. The radio sub system. The operation support sub system. There are two domain interfaces. An interface between the BTS and the base transceiver station (BTS).
8.4.2 GSM NETWORK STRUCTURE:
Every telephone network needs a well-designed structure in order to route incoming called to the correct exchange and finally to the called subscriber.
In the GSM system, the network is divided into following partitioned areas.
8.4.3 GSM SERVICE AREA:
The service is the total area served by the combination of all member countries where a mobile can be serviced.
8.4.4 PLMN SERVICE AREA:
The PLMN service area can be several within a country, based on its size.
107
The links between a GSM /PLMN network and other PSTN, ISDN or PLMN network will be on the level of international or national transit exchange.
8.4.5 MSC SERVICE AREA:
All incoming calls for a GSM /PLMN network will be routed to a gateway MSC.
A gateway MSC works as an incoming transit exchange for the GSM/PLMN. Call connections between PLMNS, or to a fixed networks, must be routed
through certain designated MSCs called a gateway MSC.
8.4.6 LOCATION AREA:
The next level of division is the MSC/VLR service area. In one PMN there can be service area .MSC/VLR is a role controller of calls
within its jurisdiction.
8.4.7 CELLS:
Lastly, a LA (Location Area is divided into many cells. A cell is an identity served by one BTS. The MS distinguishes between cells
using the Base Station Identification Code (BSIC) that the cell site over the air.
8.4.8 MOBILE STATION:
The MS include radio equipment and the man machine interface (MMI) that a subscriber needs in order to access the service provided by GSM PLMN.
MS can be installed in Vehicles or can be portable or handled stations. The MS may include provisions for data communication as well as voice.
A mobile transmits and receives message to and from the GSM system over air interface to establish and continue connections through the system.
Each MS is identified by an IMEI (International mobile Equipment Identity) that is permanently stored in the mobile unit. Upon request, the MS sends the number over the signaling channel to the MSC.
The IMEI can used to identify mobile units that are reported stolen or operating incorrectly.
8.4.9 FUNCTION OF MS:
The primary function of MS is to transmit and voice and data the air interface of the GSM system.
MS performs the signal processing function of digitizing, encoding, error protecting, encrypting, and modulating the transmitted signals from the BS.
The MS keeps the GSM network informed of its location during both national and international roaming even when it is inactive.
108
The MS includes an equalizer that compensates for multi path distortion on the received signal. This reduces Inter symbol Interference (ISI).
The MS can stored and display short alphanumeric message on the liquid crystal display (LCD). That is used to show call dialing and status information. These messages are limited to160 character in length.
8.4.10 POWER LEVEL:
These are five different categories of mobile telephone units specified by the European GSM system: 20W.8W, 5W, 2W and 0.8W.
These corresponds 43dBm, 39dBm, 37dBm, 33dBm and 29dBmpower levels.
8.4.11 SIM CARD (Subscriber Identification Module):
GSM subscriber is provided with a SIM card with its unique identification. The subscriber is identified the system when he inserted the SIM card in the
mobile equipment .This provides an enormous amount of flexibility to the subscribers since they can now use any GSM specified mobile equipment.
The SIM is a removable SC, the size of credit card, and contains an integrated circuit chip with:
A microprocessor Random Access Memory (RAM) Read Only Memory (ROM)
The subscriber inserts it is the MS unit when he or she wants to use the MS to make or receive a call.
When a mobile subscriber wants to use the system , he/she mounts their SIM card and provides their personal identification number (PIN). If the user enters three incorrect PIN codes, the SIM is disabled.
8.4.12 INTERNTIONAL MOBILE SUBSCRIBER IDENTIY (IMSI):
An IMSI is assign to each authorized GSM user. It consists of:
A mobile network code. A PLMN unique mobile subscriber identification number
(MSIN).
The NMSI consists of the MCC followed by the NMSI and shall not exceed 15 digits.
8.4.13 TEMPORARY MOBILE SUBSCRIBER IDENTITY(TMSI):
109
A TMSI is a MSC-VLR specific alias that is to maintain user confidentially. It is assigned only after successful subscriber authentication.
Under certain condition (such traffic system disruption and mal functioning of the system), the MSC can direct individual TMSIS to provide the MSC with their IMSI.
8.4.14 MOBILE STATION ISDN NUMBER:
The Ms International number must be dialed after the international prefix in order to obtain a mobile subscriber in another country.
8.4.15 THE MOBILE STETION ROAMING NUMBER (MSRN):
The MSRN is allocated on temporary basis when the MS roams into another number area.
The MSRN number is use by the HLR for re-routine calls to the MS. The MSRN for PSTN/ISDN routing shall have the same structure as
international ISDN number in the area in which the MSRN is allocated.
8.4.16 INTERNTIONAL MOBILE EQUIPMENT IDENTITY (IMEI):
The IMEI is the unique of the equipment used by a subscriber by each PLMN and is use to determine authorized (white), unauthorized (black) and mal functioning (gray) GSM hardware.
8.4.17 BASE STATION SYSTEM:
The BSS is a set of BS equipment (such as transceivers controllers). A BSS may consist of one or more BS. The interface between the BSC and
BTS is designed as A-bus interface. The BTS include two typed of machine:
The BTS in constant with the MSs through the radio interface and the BSC
In contact with the MSC.
A BTS compares radio transmission and reception devices, upon to and include the antennas and also the entire also signal processing specific to radio interface.
BTS is typically is able to handle 3 to 5 radio carries, carrying between 24 and 40 simultaneous.
8.4.18 FUNCTONS OF BTS:
The primary responsibility of the BTS is to transmit and receive radio signals from a mobile unit over an air interface.
To perform this functions completely the signals are:
110
Encoded Encrypted Multiplexed Modulated Fed to antenna system
Trans coding to bring 13kbps speeches to a standard data rate of 16 kbps and then combing four of these signals to 64 kbps is essentially a part of BTS
Random access detection is made by BTS.
8.4.19 BSC:
BSC is connected to the MSC on one side and to the BTS on the other side. It performs the radio resource (RR) management for the cells under its
control. It assigns and release frequencies and time slots for all MSS in its area. It controls the power transmission both BSSs and MSSs. It provides the time and frequency synchronization reference signals. It measures the time delay of received MS signals relative to BTS clock.
8.4.20 MSC (MOBILE SWITCHING CENTER):
The main role of the MSC is to manage the communications between the GSM users and other telecommunication networks users.
The basic switching function is performing by the MSC. The main difference between a MSC and an exchange in a fixed network is
that the MSC has to take into account the impact of the allocation of RRs and the mobile nature of the subscribers.
The MSC must also handled different types of numbers and contained in different registers: IMSI, TMSI, ISDN number and MSRN.
8.4.21 FUNCTIONS OF MSC:
It perform functions such as: Paging Resource allocation Location registration Encryption
8.4.22 VLR (Visitor Location Register):
The VLR is collocated with an MSC. A MS roaming in an MSC area is controlled by the VLR responsible for that area.
When MS appears in a LA, it starts a registration procedure. The MSC for that area notices this registration and transfers to the VLR that identify of LA where the MS is situated.
111
The VLR constitutes the data that supports the MSC in the storage and retrieval of the data of subscriber present in its area.
8.4.23 HLR (Home Location Register):
The HLR is a database that permanently stores data related to a given sets of subscriber.
Various identification number and addresses as well as authentication parameters, services subscribed, and special routing intimations are stored.
The HLR provide data needed to route to all MS-SIMs home based in its MSC area.
The HLR maintains recorded of which supplementary service each useer4 has subscribed to and provides permission control in granting services.
8.4.24 OCM (Operation & Maintain Center):
The OMC provides alarm handling functions to decoding and log alarms generated by the other network entities.
The fault management functions of the OMC allow network devices to be manually or automatically removed from or restored to service.
The status of network devices can be checked; test and diagnostics on various devices can be invoked.
The OMC provides system change control for the software revisions and configuration data based in the network entities or uploaded to the OMC.
8.5 SERVICES:-
8.5.1 GSM SERVICES:-
The ETSI Standards define the telecommunication services in the same way as ISDN does.
THREE TYPES OF SERVICES ARE AVAILABLE:-
8.5.1.1 BEARER SERVICES:
The bearer services are telecommunication services providing the capability of transmission of signal between access points (called user-network interfaces in ISDN) the bearer services described what the network could offer (e.g. speech, data and fax).
112
8.5.1.2 TELE SERVICES:
Tele-services are telecommunication services including terminal equipment functions, which provide communication between users according to protocols establishment by agreement between network operators.
The Tele-services are user end-to-end services (e.g. emergency call and SMS).
8.5.1.3 SUPPLIMENTARY SERVICES:
They are modified or supplement a basic telecommunication services .consequents they cannot be to a customer as a stand-alone service. They must be offered together or in association with a basic telecommunication services.
8.5.2 LINE IDENTIFICATION SERVICES:-
8.5.2.1 Calling Line Identification Presentation (CLIP):
The clip service allows the called party to services the line identity of the calling party. The network delivers the calling line identity to the called party at call setup time, regardless of the terminal capacity to handle the information.
8.5.2.2 Calling Line Identification Restriction (CLIR):
The CLIR services enable the calling party to restrict presentation of its line identity to called party. For inter-network calls, when the CLIR service is invoked, the originating network provides the destination with notification that the identity of the calling party is not allowed to be presented to the called party.
8.5.2.3 Connected Line Identification Presentation (COLR):
The COLR service allows the connected party to prevent presentation of line identity to the calling party. The network automatically invokes the
COLR services for each incoming call at setup phase. When the COLR services invoked, the destination provides originating
network with a notification that the line identity of the connected party is not allow to be present to calling party.
8.5.3 CALL OFFERING SERVICES:-
8.5.3.1 CALL FORWARDING UNCONDITIONAL (CFU):
This service permits a called mobile subscriber to have the network send all incoming calls (or just those associated with a specific basic service group), addressed to its directory number, to another directory number.
113
8.5.3.2 CALL FORWARDING ON MOBILE SUBSCRIBER BUSY (CFB):
This service permits a called mobile subscriber to have the network send all incoming calls that reach a busy signal, to another directory number.
8.5.3.3 CALL FORWARDING ON MOBILE SUBSCRIBER NOT REACHABLE:
This service permits a called mobile subscriber to have the network send all incoming calls addressed to her directory number, but which is not reachable, to another directory number.
8.5.4 CALL COMPLATION SERVICES:-
8.5.4.1 CALL WAITING (CW):
The call waiting service permits a mobile subscriber to be notified of an incoming call, while the traffic channel is not available for the incoming calls and the mobile subscriber is engaged in an active or held call.
8.5.4.2 CALL HOLDING (HOLD):
The call holding service allows a served mobile subscriber, who is provisioned with this supplementary service, to interrupt communication on an existing active call and reestablish communication.
8.5.5 MULTI PARTY SUPPLEMENTARY SERVICES:-
8.5.5.1 MULTY PARTY SERVICE (MPTY):
The service provides a mobile subscriber with the ability to have a multi-connection call.
A pre-condition for the MPTY service is that the served mobile subscriber is in control of one active call and one call hold, both calls having been answered.
8.5.6 CHARGING SUPPLEMENTARY SERVICE:-
8.5.6.1 ADVICEOF CHARGE (INFORMATION) (AOCI):
This service permits the mobile station to display an accurate estimate of the size of the bill which will eventually be levied in the Home PLMN (HPLMN).
114
8.5.6.2 ADVICEOF CHARGE (CHARGING) (AOCC):
This service allows the mobile subscriber to indicate the charge that will be made for the use of telecommunication service.
It is intended for applications where the user is generally not the subscriber but is known to the subscriber, and where the user pays the subscriber, rather than the service provider.
8.5.7 CALL RESTRICTION SERVICES:-
These services allow the possibility for a mobile subscriber to bar certain categories of outgoing incoming calls.
115