Ocb 283 Introduction Telecommunication Networks Are Constantly Changing. the Rapid Growth

Ocb 283
Introduction
Telecommunication Networks Are Constantly Changing. The Rapid Growth Of The Digital Network, Mobile Network And Intelligent Network And The Proliferation Of New Services Being Constantly Offered To Subscriber Means That Equipment Must Be Continuously Adapted To New Requirements. All The New Switching Systems Are Based On Stored Program Control Concept. The Call Processing Programmes Are Distributed Over Different Control Organs Of The System And Are Stored In Rom/Ram Of The Units Processor In The Control Units By Using The Programme And Data Stored In Unit Rom/Ram Process And Handle Calls. Handling Or Processing A Call Means To Ultimately Establish A Connection In Between Incoming And Outgoing Ends. Depending On The System The Name And Architecture Of Control Units And Switch May Change But Basic Criterion For Switching More Or Less Remains Same.
The Alcatel 1000E10 Exchange Also Known By Its Other Name Ocb283 Is Designed To Cater For Evolving Networks And The Need To Rationalize Equipment Operation. Its Modular Architecture Means That New Services Can Be Added And Processing Capacity Can Be Increased Without Interrupting Operation Of The Exchange. Ocb 283 Is A Digital Switching System Which Supports A Variety Of Communication Needs Like Basic Telephony, Isdn, Interface To Mobile Communication, Data Communication Etc. This System Has Been Developed By Alcatel Of France And Therefore Has Many Similarities To Its Predecessor E-10. The First Ocb283 Exchange Of R11 Version Came To India In 1993. At Present R23 And R24 Are Also Being Supplied. The Basic Architecture Remaining Same, More Facilities To Subscriber And Administration Are Supported By Later Versions.
Features Of The System
I. It Is A Digital Switching System With Single ‘T’ Stage Switch. A Maximum Of 2048 Pcms Can Be Connected.
Ii. It Supports Both Analogue And Digital Subscriber.
Iii. The System Supports All The Existing Signaling System Like Decadic, Mf, Cas And Also Ccitt#7 Signaling System.
Iv. It Provides Telephony, Isdn, Data Communication, Cellular Radio And Other Value Added Services.
V. The System Has ‘Auto Recovery’ Feature. When A Serious Fault Occur In A Control Unit, It Gives A Message To Smm(Operation & Maintenance Unit). The Smm Puts This Unit Out Of Service, Loads The Software Of Faulty Unit In A Backup Unit And Bring It Into Service. Diagnostic Programmes Are Run On The Faulty System And Diagnostics Are Printed On The Terminal.
Vi. Ocb283 Has Double Remoting Facility. Subscriber Access Unit Csnd Can Be Placed At A Remote Place And Connected To The Main Exchange Through Pcm Links. Further Line Concentrators Are Placed At A Remote Location And Connected To The Csnl Or Csnd Through Pcms. This SpecialFeatureCanMeetEntireRange Of Necessities Like Urban, Semi-Urban And Rural.
Vii. Various Units Of Ocb283 System Are Connected Over Token Rings. This Enables Fast Exchange Of Information And Avoid Complicated Links And Wiring Between Various Units.
Viii. The Charge Accounts Of The Subscribers Are Automatically Saved On The Disc, Once In A Day. This Avoids Loss Of Revenue In Case Of Total Power Supply/ Battery Failure Or Any Other Type Of Exchange Failure.
Ix. Traffic Handling Capacity Of The System Is Very Huge. It Can Handle 8,00,000 Bhca And 25,000 Erlangs Of Traffic. Depending On The Traffic, A Maximum Of 2,00,000 Subscribers Or 60,000 Circuits Can Be Connected.
X. The Exchange Can Be Managed Either Locally Or Through Nmc Of 64Kbps Link.
Xi. The Ocb283 System Is Made Up Of Only 35 Different Type Of Cards. This Excludes Cards Required For Csn. Because Of This The Number Of Spare Cards Required For Maintenance Purpose, Are Drastically Reduced.
Xii. All The Control Units Are Implemented Are Implemented On The Same Type Of Hardware. This Is Called A Station. Depending On The Requirement Of Processing Capacity, Software Of Either One Or Several Control Units Can Be Located On The Same Station. For All These Control Units, Only One Backup Station Is Provided, Enabling ‘Automatic Recovery’ In Case Of Fault.
Xiii. The System Has Very Modular Structure. The Expansion Can Be Carried Out Very Easily By Adding Necessary Hardware & Software.
Xiv. The Smm(O&M Units) Are Duplicated, With One Active And Other Hot Standby. In Case Of Faults, The Switchover Takes Place Automatically. Moreover, Discs Are Also Connected To Both The Smms, There Is No Necessity Of Changing Of Cables From One To Another.
Xv. The Hard Disc Is Very Small In Size, Compact And Maintenance Free. It Has A Very Huge Memory Capacity Of 1.2Gb. The Detail Billing Data Are Regularly Saved In These Discs Itself, From There It Can Be Transferred To The Magnetic Tapes For The Purpose Of Processing.
Xvi. There Is No Fixed Rack And Rigid Suite Configuration In This System. It Provides Greater Flexibility And Adjustment In The Available Space.
Xvii. This System Can Work At A Temperature 5°C To 45°C, Though The Optimum Temperature To Work Is 22°C.
Subscriber Facilities Provided By Ocb283
It Provides A Large Number Of Subscriber Facilities. Some Facilities Are Available To Only Digital Subscriber And As Such They Can Not Be Availed By Analogue Subscribers. To Avail These Facilities Subscriber Number Are Given Special Categories By Man Machine Commands.
I. A Line Can Be Made Only Outgoing And Incoming.
Ii. Immediate Hotline Facility – The Subscriber Is Connected To Another Predetermined Subscriber On Lifting The Handset, Without Dialing Any Number.
Iii. Delay Hotline Facility – When Subscriber Lifts The Handset, Dial Tone Is Provided, He Can Dial Any Number. If He Does Not Dial A Number, Within A Predetermined Time, He Is Connected To Predetermined Number.
Iv. Abbreviated Dialing – The Subscriber Can Record A Short Code And Its Corresponding Full Number In The Memory. Later To Dial This Number He Has To Dial Only Short Code Of That Number.
V. Call Waiting Indication – When A Subscriber Is Engaged In Conversation And If Getting An Incoming Call, An Indication Is Given In The Form Of A Tone. Hearing This, The Subscriber Has Option, Either To Hold The Subscriber In Conversation And Attend The Waiting Call Or To Disconnect This Subscriber And Attend To The Waiting Call. In The Former Case He Can Revert Back To The Earlier Subscriber.
Vi. Call Forwarding – When Provided, Incoming Calls To The Subscriber Gets Transferred To The Number Mentioned By The Subscriber While Activating The Facility. This Facility Is Especially Very Useful For Those Person Who Are Always On Move.
Vii. Conference Between 4 Subscribers – The Subscriber A & B While In Conversation, Can Include Two More Subscriber By Pressing ‘* Button’ And Dialing Their Numbers.
Viii. Automatic Call Back On Busy – If This Facility Is Activated And If The Called Subscriber Is Found Busy, The Calling Subscriber Simply Replaces The Receiver. The System Keeps Watch On The Called Subscriber And When It Becomes Free, A Ring Is Given To Both The Subscribers. On Lifting They Can Talk To Each Other.
Ix. Priority Lines – Calls From These Lines Are Processed And Put Through Even When The Number Of Free Channels Are Within A Threshold Or When The System Is Operating In Catastrophic Mode.
X. Malicious Call Identification – When This Category Is Given To A Subscriber, The Number Of Calling Subscriber, The Number Of Calling Subscriber To This Number Is Printed On The Terminal Or Displayed On The Caller Identification Instrument.
Xi. 12 Or 16Khz Meter Pulses – The System Can Send 12 Or 16Khz Meter Pulses On The Subscriber Line For The Operating Of The Home Meter.
Xii. Battery Reversal – The System Extends Battery Reversal When Called Subscriber Answers. This Is Useful In Case Of Ccbs( Coin Collection Box ).
Xiii. Detailed Billing – The System Provides Detail Bills Given Details Of Date, Time, Metered Units Etc.
Xiv. Absent Subscriber Service – When Activated, The Incoming Calls Are Diverted To Absent Subscriber Service For Suitable Instruction Or Information.
Xv. It Provides 64 Kb/S Digital Connectivity Between Two Subscribers For Data Communication.
Xvi. This System Provides Facsimile (Fax) Services And Videotext Services Also.
Xvii. This System Also Provides The Facility For Restriction Of The Display Of Calling Subscriber Number On Called Subscriber’S Telephone Terminal Or Caller Id Set. To Avail This Facility The Subscriber Has To Be Given A Category Like Some Vvips Or Some Beurocrats.
Xviii. User To User Signaling – The System Permits Of Mini Messages Between Calling And Called Subscribers During Call Setup And Ringing Phase.
Xix. Terminal Portability During The Call – A Subscriber (Calling Subscriber As Well As Called Subscriber) Can Unplug Telephone Instrument, Carry It To Some Other Place Or Room And Resume The Call Within 3 Minutes
Xx. Listing Of Unanswered Calls – The Number Of Calling Subscribers, Who Calls During The Absence Of Called Subscriber, Are Recorded In Called Subscriber’S Terminal. The Called Subscriber Than Check Up These Numbers And Call Them Back, If He So Wishes.
Xxi. This System Provides Two Type Of Isdn Connections To The Digital Subscriber, One Is Of 2 B + D Line (2 Voice Channels Of 64Kbps & I Data Channel Of 16Kbps) Type And Other Is Of 30 B + D Line (30 Voice Channels Of 64Kbps & 1 Data Channel Of 16Kbps) Type.
Common Channel Signaling No. 7 (Ccs#7)
Introduction
The Latest Signaling Now Being Implemented Worldwide Is Common Channel Signaling Or Also Called Ccs#7 Signaling. This Type Of Signaling Is Essential For The Setting Up Of The Isdn (Intelligent Services Digital Networks) Services.
In This Type Of Signaling The Signaling Information Is Sent From One Exchange To Other Exchange (Called Signaling Points Sp) In The Form Of Messages Coded In Binary Form, Which Is Understandable By The Intelligent Devices Available At Both The Ends Means In Both The Exchanges. The Ccitt (Consultative Committee On International Telecom Treaty) Organization Has Recommended A Standard Protocol Called Ccitt#7 Signaling. The Signaling Message Travels Over A Single Time Slot Of The Pcm Connecting The Two Exchange (Signaling Point Sp). This Time Slot Is Called Common Channel For Signaling, Hence The Name Common Channel Signaling. The Message Over This Common Channel Carry All Relevant Data For Any Of The Other Time Slots Or Circuits Which Carry Voice Or Subscriber Data. The Channels For Subscriber Are Called Voice Channels.
Common Channel Signaling
Voice Channels
Common Channel
For Signaling
.
Signaling Points
The Ocb283 Exchange Uses Common Channel Signaling Between Its Csn & The Common Control Equipment Also. Signaling Is Often Referred To As Glue, Which Holds A Network Together. It Provides The Ability To Transfer Information Between Subscribers, Within Networks & Between Subscribers And Networks. Signaling Is The Lifeblood, The Vitalizing Influence Of Telecommunication Networks. Without Signaling, Networks Are Inert. By Providing Effective Signaling System, A Network Is Transformed Into A Tremendously Powerful Medium Through Which Subscriber Can Communicate With Each Other Using A Range Of Telecommunication Services. Old Signaling System That Was Simple Mechanisms For Transferring Basic Information Are Being Replaced By Efficient Data Transfer Highways. It Is Signaling That Provides The Ability For Subscriber To Indicate To The Exchange That A Call Is Required. It Also Allows The Called Subscriber To Be Identified E.B. By Transferring The Telephone Number Dialed By Calling Subscriber.
It Allows The Transfer Of Information Between Exchanges In The Network To Establish And Release The Call. It Transforms The Foundation Of Network Into An Active Entity That Can Provide The Required Services To The Subscribers. It Consists Of The Instructions, Which Originate From The Telephone User On The Form Of Lifting The Handset In Order To Make A Call, The Transmission Of Dial Pulses Generated By Operating A Dial & Replacing A Receiver At The End Of The Call. Instructions Are Also Signaled By Exchange In The Form Of Dial Tone, Ringing Tone Etc., To Indicate The Progress Of The Call. In Addition Inter Exchange Signaling Takes Place Between A Call Is Set-Up, To Control Exchange Operations & & Check On Circuit Availability.
Types Of Signaling
Telephony Started With The Invention Of Magneto Telephones, Which Uses A Magnet To Generate The Ringing Current, The Only Signal Sent Over A Dedicated Time Between Two Subscribers. As The Switching Technology Has Undergone A Vast Change From Manual Switching To Digital Switching, The Inter Exchange Signaling Techniques Have Also Progressively Changed From Loop No Loop Signaling To Mf Signaling & Finally Digital Signaling. The First Digital Switching Developed Was Channel Associated Signaling In Which The Signaling Information Is Conveyed On A Separate Channel, Which Is Rigidly Associated Channel. The Utilization Of Such A Dedicated Channel For Each Speech Channel Is Highly Inefficient, As It Remains Idle During The Entire Speech Phase. Hence A New Signaling System Was Developed Which Is Capable Of Providing All New Services & Its Internationally Standardized Is Known As Common Channel Signaling.
Signaling In Pulse Code Modulation
Pulse Code Modulation (Pcm) Is A Method Of Converting Information From An Analog Form To A Digital Form For Transfer Over A Digital Transmission Systems, The Technique Involves Sampling The Analogue Waveform And Coded The Result In The Digital Format. Successive Sampling Allows The Analogue Waveform To Be Represented By A Series Of 8-Bit Code. 8 Bit Codes Form Numerous Speech Channels Are Assembled Into Blocks For Transmission By Inserting Into Time Slots. The Technique Is Called Time Division Multiplexing (Tdm).
The Bandwidth Required To Transmit Signal Is Much Less Than That For Speech, So That Signaling For Several Speech Channels In A Pcm System Can Be Handled By A Small Portion Of The Bandwidth. The Signaling Capacity Can Be Used For Cas Or Ccs, The Means Of Identifying To Which Speech Channel A Particular Signal Refers Is To Divide The Signaling Capacity Into Dedicated Bit Locations. Signal Pertinent To A Particular Speech Path Are Always Transmitted In Signaling Bit Locations Dedicated To That Speech Channel. The Means Of Conveying Ccs Is To Compound The Signaling Capacity Into A Signaling Channel That Is Available As And When Required.
The Ccitt Has Defined Pcm Standards For 30 Channel And 24 Channel Systems. The Capacity Available For Signaling In These Two Standards Is Different As A Result Of Differing Constraints Applied By The Pcm Standard.
In 30 Channel Pcm Systems, The 8-Bit Code Relating To 30 Speech Channels Are Time Divisioned Multiplexed Into A Frame. Each 8-Bit Code Is Inserted Into A Time Slot Within The Frame. Time Slot 0 Is Used For Alignment; Time Slots 1-15 And 17-31 Are Used For Encoded Speech Related To 30 Channels. The Slot 16 Is Dedicated For The Use Of Signaling.
The Tenet Of Cas System Is That Dedicated Signaling Capacity Is Available For Each Speech Circuit. This Is Achieved In 30 Channel Pcm Systems By Allocating 4 Bits In Each 16-Frame Multi-Frame To Signaling For Each Speech Channel.
Frame
Multi-Frame
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Speech Channel
Time Slot
Frame
- 1 2 3 15 - 17 28 29 30
0
1 2 3 15 16 17 29 30 31
Bits
1 2 3 4 5 6 7 8
Fig. : Frame Structure Of 30-Channel Pcm System
Principle Of Ccs
In Common Channel Signaling Systems, The Physical Tie Between The Signaling Path And Traffic Circuit Is Removed. All Signaling Transfer Relating To A Transmission Link Takes Place Over A Dedicated Signaling Channel. Hence, A Common Signaling Channel Handles The Transfer Of Signaling Information For Numerous Traffic Circuits. Signaling Capacity Is Not Reserved For Each Circuit, But Signaling Capacity Is Allocated Dynamically As When Required. Fig. Shows The Concept Of Ccs For Both Access And Inter-Exchange Signaling. Exchange A And B Are Connected By Numerous Speech Circuits, Denoted By Solid Lines. All The Signaling That Relates To The Speech Circuit Is Transferred Between The Exchanges Using The Common Signaling Path (Denoted By Dotted Lines). The Common Signaling Path Can Be Regarded As A Pipe Between Two Exchanges, Typically Operating At 64 Kbps, Into Which All Signaling Information Is Funneled. Similarly, All Signaling Information Pertaining To The Speech Circuit Between Each Subscriber And Exchange A Is Transferred Via The Access-Signaling Channel.
Speech
Fig. : Ccs Signaling : Associated Mode Of Operation
The Transfer Of Signaling Information Is Achieved By Sending Message Down The Common-Signaling Path. The Use Of Message In Ccs Systems Opens Up A Whole Range Of Flexibility That Is Not Present In A Cas System. Instead Of Being Limited To A Small Number Of Meanings For Signals Messages Can Be Designed To Cover Multitude Of Situations And Services.
The Signaling Activity When Setting Up & Releasing A Circuit Is High; However On An Average The Signaling Activity For A Circuit Is Low Because There Are No Signaling When The Calls Are Not Being Made & During The Conversation Phase Of The Call. Hence, A Single Ccs Channel Can Be Used To Use Numerous Traffic Circuits. The Theoretical Limit Of The Number Of Traffic Circuits Handled By Ccs Channel Is Very High, But A Typical Practical Value Is 2000Traffic Circuits. The Picture Become More Complex When Non-Circuit Related Signaling Activity Is Taken Into Account. Non Circuit Related Signaling Can Be Intermittent (E.G. It Is Used During Call Establishment To Interrogate A Database) Or It Can Exhibit A High Signaling Activity (E.G. If It Is Used To Transfer A Large Amount Of Management Data Between Nodes In A Network).