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AXE10 - Overview
• M/s Ericsson Telecom , Sweden• BHCA – busy hour call attempts capacity 8,00,000• CCS-7 & ISDN support• 26,000 Erlang• Blocking factor 10 power -6 ie one call in
10,00,000 may fail due to blocking in group switch.
• Hardware redundancy – duplicated hardware – built in check functions – automatic block and switch over
Salient features- Design• SPC stored programme control• PCM principles• TST time space time principle.• Duplicated CP central processor• RPs – regional processors• Functional modularity – smoother, quicker
hardware extension, system upgradation is easier, new functions easily incorporated
• Highest degree of backward compatibility• One system for all applications – local, transit,
Mobile switching centre, hybrid
Functional hierarchy
AXE – Subsystems in APTBoth software and hardware• SSS – subscriber switching subsystem• GSS – group switching subsystem• TSS – trunk and signalling subsystem• CCS- common channelling subsystem• OMS – operation and maintenance subsystemOnly software• SUS – subscriber services subsystem• CHS – charging subsystem• TCS – traffic control subsystem
AXE – Subsystems in APZ
• CPS – central processor subsystem• RPS – Regional processor subsystem• IOG – input output group
- FMS File management subsystem- MCS Man machine communication- SPS Support processor subsystem- DCS Data communication subsystem
Functional blocks
• Each subsystem will have functional blocks.• Eg BT both way trunk is a functional block in
TSS . Software in RP is BTR, Software in CP is BTU.
• Interworking between function blocks is only through CP
• Data of a function block is accessed by its own program only.
SSS – subscriber switching subsystem
Functions• BORSHCT function• Battery feed- (-48V DC)• Overvoltage protection• Ringing current• Subscriber line signalling• Hybrid – 2 wire to 4 wire conversion• Concentration/expansion• Testing of subscriber lines
SSS functions
• Analogue to digital / D to A conversion• Switching • Scanning for off/on hook• Digit / tones receiving• Control tones
• CJ - combines junctor– a coordinating function block – coordinated all functions in the SSS subsystem – only software
SSS functions
• Switching within SSS
Switching ( time slot change)Calls within same EMG switched without using
GSS
A/D
A/D
Internal PCM Lines (pmt access for every subs
EMTS
Extl PCMGSS
SSS – concentration/expansion
• EMG = 2048 subscribers• PCM lines – 32 pcms 2048:1000 = 2:1 8 pcms 2048: 256 = 8:1• Max 32 pcms, min 2 pcms• PCMs between SSS and GSS are called system
lines
Subsciber line signalling
• On/off hook – scanning• Dial pulses• Tones• Control tones• Ringing signals
MSU and RSU
• Local subscriber switches – MSU – LSS normally called Local EMG – Extension module group• Remote subscriber switches – RSU – RSS - normally called Remote EMG• MSU and RSU can be differentiated by some
hardware units
SSS - Hardware• EMG Extension module group - LSM –A (Line switch magazine – analogue)
- LSM –BA ( ISDN BRA)- LSM – PRA ( ISDN PRA)
• SEPRM – special equipment for private meters• SULTACCS subs line testing and feeding howler
tone – one for every 4 LSS• RPBC – pair – interfacing between LSS andCPs• IOSULT –in RSU only – testing of subs lines,
howler tone, V.24 I/O for man-machine communication
SSS - hardware
• 1 EMG = 2048 customers• 1 LSM A = 128 subscribers
• RSU to GSS = max 32 pcms, each pcm chl-0 for synch and chl-16 for signalling
• MSU to GSS = 32 pcms always – synch and signalling separate bus
SSS – Hardware units
• POU – power unit• REU – ringing current eqpt unit ie ring generator (
1 per EMG)• EMTS – Extension module time switch• KRC – keyset receiver circuit• LIB – line interface board LIBA, LIPA• SLCT – subs line and circuit tester• ETB/JTC – exch terminal board (RSU) /junctor
terminal circuit (MSU)
SSS HardwareHardware Function
LIB Detection of on/off hook, Ring trip
Digit reception pulse, A/D conversion
Power feed, Ringing relayKRC Digit reception tone
EMTS Control tone generator, switchingREU Ringing signal generator
ETB/JTC Concentration/expansion
SSS – important points
• No traffice balancing is requirred – ie any subs to any LIB
• Call meter associated with subs telephone number
• Each EMG need not have dedicated PCM with GS
• Each EMG need not have a KRC board – common pool – all subs .
GSS – group switch subsystem• Both software and hardwareFunctional blocks• GS – group switch – Time switch module and space
module. Performs path selection and release of the established connections.
• GSM1 and GSM2 – group switch operation and maintenance function
• CCD – conference call device – upto 32 participants• CLT – clock generation and timing – 3 clock modules,
supplies clock pulses to TSMs and SPMs• NS – Network synchronisation with other digital
exchanges.• Routine tests – SNEFI, SNEFD, SNETR, SNEAL
GSS – contd….• GSS is a central part of the system• Almost all calls and signalling systems use GSS
to connect hardware to various channels.• Other subsystems that interwork with GSS• For traffic handling
TCS, TSS, SSS• For O & M
OMS –call set up and release of test calls• Others SUS – subscriber services
GSS - Hardware
• ETC – exchange terminal circuits• CCD – conference call devices• PCD – pulse code devices – for analogue
devices
• SNT – SNTP switching network terminal point• 128 TSMs with 4x4 SPMs – 65536 cross point• This is called 64K Group switch
GSS
• CLM clock module - Three clocks CLM0, CLM1 and CLM2– one is master – VCXO voltage control crystal oscillator.
• TSM uses two clock rates – 4096 MHz for internal speed of the switch, 8kHz for synchronisation of the switch.
TSS – Trunk & signalling subsystem• Both hardware and softwareFunctions• To handle trunk lines• handle signalling to & from other exchanges• Supervising the digital lines DIP• Synchronisation
• DIP – digital path – E1 terminations in ETC cards
Functional blocks• BT – bothway trunk – responsible for the traffic
handling functions of the trunk lines• BTM – Both way trunk maintenance – responsible for
O & M functions related to trunk lines• CSR – code sender/received – functions for signalling• ET – handles ETC and synch of DIPs – owns and
supervises the exchanges’s ETCs.• DIPST – Dip supervision & test – handles errors
detected on the DIP. Alarms are generated if limit values set by command are exceeded.
• C7BTC – C7 BT coordination• C7CMNT – C7 circuit maintenance
TSS - Hardware
• ETC – exchange terminal circuit EI• CSR – code sender receiver----------------------------------------R – routeRouting analysis – sending program 3 digits1 digit – when to seize an outgoing device2 digit – when to send seiqure signal to other exchange3 digit – which digit to send as the first digit to the next
exchangeEg. SP = 664
TSS - signalling
• CSR – code sender / receiver• CIU – CSR interface unit• CTU – CSR tone sending unit• CCC – CSR control unit
CCS – common channel signalling subsystem
Software and HardwareFunctions• Implements C7 signalling in AXE-10• Delivers signalling packages between two
signalling points• Error detection/correction – order of the
signals.• MTP message transfer part in implemented in
CCS.Note: User part is implemented in TSS
Functional blocks in CCS• C7ST2 – signalling terminals – terminations.• C7DR2 – discrimination, distribution and routing.
This block reads the destination information in the signalling units and routes it to the correct user or reroute
• C7DP2 – destination point mangement – this block administers the destination points in the network
• C7LS2 – link set management – handles link sets • C7SL2 – signalling link management – handles
signalling links
CCS - Hardware
• ST – signalling terminals• PCDD – pulse coding device , digital – rate
adaption – ie 64 kpbs that come from the signalling terminals are put together into one 2 Mbps pcm line.
C7 – important points
• MTP is the transport service of C7• Different user parts utilize the services offered
by the message transfer part• The telephone user part TUP for plain old
telephony service POTS• Signalling points and signalling transfer points
are components in the signalling network• A signalling link is a 64 Kbit link with one
signalling terminal ST at each end.
TCS – Traffic control subsystem• Only software• TCS occupies a central position in the AXE• TCS’s tasks include controlling the set-up and
clearing phases• Stores subscriber data, circuit data
TCS
GSS TSS SSS CCS MTS
TCS – Function blocks• RE – register function – this block stores the
incoming digits and handles the set-up of calls• CL – call supervision – this block supervises calls
in progress and clears them.• DA – digit analysis – this block contains tables for
digit analysis• RA – Route analysis – this block contains tables
for selecting outgoing routes • SC – subscriber categories – this block stores
subscriber categories for all subscribers connected to the exchange
TCS – Function blocks• TOM – Trunk offering management – this
block takes over the functions of RE or CL when a busy subscriber is to be supervised by an operator
• COF – Coordination of flash services – this block takes over the functions of CL when more than two subscribers are to take part in one and the same speech connection
SUS – subscriber services subsystem
• Only software• Provides subscriber services like call transfer, call waiting,
dynamic STD barring, etc.Some important parameters• LIC – line interface circuit – • Hundred groups – level of exchange• SULII – subs line interface initiate• SULIE – subs line interface end• SUSCP – subs category print• SUSCC – subs category adding/changing/deleting a
category• SCL – parameter for subs category Eg. Scl = HLI -1 hotline
SUS – subscriber services subsystem
• PABX – PABX and PABX with indialling • Hunting facility – HNB=1 rotary hunting,
HNB=0 sequential hunting• Abbreviated dialing – ADI-1 operator
controlled, ADI-2 subs controlled• STD barring CBA-1, provisioning CBA-0.• Subs controlled barring – CCB-2 & KWC-1• DNP – TBO-2 & BIC-1
SUS• Outgoing only – BIC-1• Incoming only – BOC-1• Call forwarding
Unconditional CFUV-1Busy CFBV-1No Reply CFNRV-1
• Call waiting CAW-1 & FLA-2• Printing of call meter value – CHSIP• Testing of LICs – SLOCI:DEV = LI-xx&&yy; 4
numbers
CHS – Charging subsystem
• Software only• Charging functions
1. Charging method2. Charging analysis
• CHS has external and internal interfaces • External
CHS-TCS information regarding subscriber services, normal calls and accounting
CHS – Charging subsystem
• CHS-SSS – special equiment like SEPRM• CHS-TSS – incoming and outgoing calls
charging• CHS –CP – reading system information like
date, time, day, etc
CHS – charging method
• Pulse metering PM – Pure Karlsson method ( no start pulse)Modified Karlsson methodIndividual periodic methodPre-emptive metering method ( start pulse)
• Toll ticketing TT – Ttfilexx CDR
CHS – charging analysis
• End of selection• Charging case• Type of A-subscriber• Call tye
Yet to cover
• Call handling• APZ subsystems• System maintenance philosophy
• ISDN