Ccr Improvement Ocb

Office of the Chief General Manager National Centre for Electronic Switching ARA Centre, Mezzanine Floor E-2, Jhandewalan Extension, New Delhi-55 Tel No: 23670334, Fax No: 23552387 No. ND/ NCES/ 24-1/Vol.II/36

Dated: 27.01.2007

All CGMs Telecom Circles/ Districts All CGMs Maintenance Regions Sub: Maintenance support (AMC for hardware and software) for OCB-283 New Technology Switches: Improvement in CCR (call completion ratio) Kindly refer to the AMC agreement signed with Alcatel and ITI for maintenance support of OCB-283 New Technology Exchanges in BSNL network. 2. It has been expressed by Telecom Circles during various zonal quarterly performance review meetings of AMC of New Technical Exchanges that after yearly preventive maintenance visits by the AMC vendor, the exchanges should achieve the targets of critical performance parameters (CCR, ASR, PE, CSR etc). AMC vendors represented that during preventive maintenance visits, they are basically trying to remove all the alarms and faults in the exchange. 3. In this context, CGM, NCES mentioned that as nearly two years of AMC operations are over and issues of AMC are more or less stabilized, hence it is high time to use the services of AMC vendors in more prudent manner such as to improve the CCR of NT exchanges and provision exists for the same in the AMC agreement. 4. Alcatel and ITI were requested to generate a technical note for improvement of CCR in OCB-283 exchanges. Alcatel and ITI have submitted the technical note regarding improvement of CCR in OCB-283 exchanges and the same are enclosed herewith for kind reference. 5. It is suggested that Circle nodal officers [PGM(O)/GM(O)/GM(Mtce)] may kindly coordinate with Alcatel and ITI so as to arrange for demonstration of the implementation of enclosed technical note in one of the OCB-283 exchanges by each Alcatel and ITI in the Circle which exchange in-charges of other OCB-283 exchanges of the Circle may also attend. Thus, the technical notes submitted by Alcatel and ITI may be implemented in all OCB-283 exchange for improvement of CCR and thereby resulting into increased revenue. 6. Copy of this letter is also available at BSNL Intranet portal (http://intranet.bsnl.co.in) under the heading BSNL UNITS → Specialized Units → NCES. 7.

This issues with the approval of CGM, NCES, New Delhi.

(V. K. KANAUJIA) Dy. General Manager (Technical) Tel: 011 - 2351 6108 Enclosures: 1) Technical note of Alcatel: Exchange CCR Efficiency improvement (7 pages) 2) Technical note of ITI: Tips for improving CCR in OCB-283 exchanges (2 pages) Copy to: 1. Director (Operations), BSNL, Statesman House, New Delhi 2. Sr. DDG (MS), BSNL Corporate Office, Statesman House, New Delhi 3. DDG (NM), BSNL Corporate Office, Statesman House, New Delhi

Regd. Office: B-148, Statesman House, Barakhamba road, New Delhi-110 001 Corporate Office: B-148, Statesman House, Barakhamba road, New Delhi-110 001 Website: www.bsnl.co.in

Establishment

ALCATEL INDIA LTD.

GURGAON

Exchange CCR Efficiency improvement Area

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ALCATEL 1000 E10 ( OCB 283 )

Department or service

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OPERATION DIRECTION

Type

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TECHNICAL NOTE

APPLICATION

IMPLEMENTATION BY

SITE

01

4006

Atul Chawla

Ramesh Partha

ED

WEEK

APPROVAL

ORIGINATOR

History : Ed 01 : Document Creation

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INDEX 1.

MAIN REASONS FOR LOW CCR

3

2.

RECOMMENDATIONS FOR CCR ENHANCEMENT

4

3.

APPENDIX A : LOAD-BALANCING AMONG (PUPES)

6

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1. MAIN REASONS FOR LOW CCR AND TRAFFIC/ 1000BHCA

1. Congestion on routes : This is the most common cause of low call efficiency in exchanges. The exchanges have been supplied for a maximum per circuit erlang traffic of 0.7E. 2. Incorrect combination of routing parameters : An incorrect/inefficient combination of routing parameters can lead to a much higher load per call especially in a congested senario. 3. Subscriber Behaviour : This of course is one of the main cause of low efficiency. The main reasons are busy_called_line , incorrect dialing , incomplete dialing , on-hook before answer etc 4. Overloading of CCS7 resources : Exceeding the traffic on CCS7 resources to more than it has been dimensioned/ordered for. This also happens due to loading of circuits beyond 0.7 Erlangs. Creating more than dimensioned no of CCS7 circuits in the exchange also has a similar affect. 5. Uneven distribution of C7 load among C7 processing stations.

Specific to lower Traffic/ 1000 BHCA: 1) % of calls involving mobile subscribers is very high now. Average holding time of mobile call is less due to: a) Cost of cell call b) Call disconnection by called cell sub c) Other reasons like travelling, outside area,battery low, etc. d) Ringing time is very less compared to landline call e) During Busy Hour, % of failed calls is more in Cell routes due to congestion, etc 2) % of R2MF calls is very less now. Average call setup time is less than 500 millisec for CCS7 calls whereas for R2MF calls it is more than 6 seconds.

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2. RECOMMENDATIONS FOR CCR ENHANCEMENT

a) Increasing circuits in the congested circuit groups. The aim has to be to reduce the per circuit traffic to within 0.7E . Traffic planning should target a load of upto 0.6E as a steady state load in normal busy hour so that appropriate margin is kept for traffic peaks . b) CCS7 resources are to be loaded within dimensioned capacity. The traffic planning should target a steady state load of 15% less than the dimensioned load so that appropriate margins are kept for traffic peaks which are a common feature in live environment c) Evenly distribute the load among CCS7 stations ( PUPEs) as per the relevant technical document . d) In local exchanges go for higer depth of analysis wherever possible to avoid the cases of wrong/incomplete dialing from reaching TAXs. e) NT ( Number of retrials ) should be 1 in all Type 11 ACHs ( distribution of traffic among constituent ACHs based on a defined % ) in the congested directions , to avoid unnecessarily high number of repeated route selections. f) Keep RCR on No.7 routes maximum. to reduce SAMs; maximize RCA to reduce MR-TR interactions. g) Optimising load on the process of selecting a free circuit: Large size Bothway Trunk Groups can be split into two or more small trunk groups (say 512 CICs maximum) . Routing of levels can be split among these smaller trunk groups. h) Precollect CLI(DP7) onincoming R2 to reduce INR-INF (CLI request messages ) on o/g No.7 i) Use FINU ( end of called number ) on originating local exchanges so that the receiving exchange knows when all the address digits have been sent and does not wait unnecessarily for more digits j) Use correct/appropriate LAW on both sides of C7 links to reduce double seizures k) Also for equal or best approximation balancing of signalling traffic on COCs., use LAW=23 for FSMs with 5,6 or 7 COCs ; law 31 for FSMs with 8 cocs,law=1,3,7,8 for FSMs with 1,2,3 and 4 cocs respectively l)

Please check to avoid translator loopings (ACHxÆACDy->..->ACHx)

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The document OBRECOCB available in the ADES electronic documentation details the meaning of each OCHLA counter . Typical pulldowns: T12A: Incoming incomplete numbers. Maximize seizure point in parented exchanges T14A: Wrong codes received. Increase depth of analysis in originating local exchanges T47T: Forced release from MSCs after playing busy/out of reach announcements—no control T18T:Release by calling upon listening to busy/out of reach announcements—no control T22T: called party busy---put announcement in RNV 145 to prevent repeated redialing at short intervals T37A: Load moification in PUPE/MR/CC: -If MR/CC overload , RATED bhca has been exceeded - if PUPE overload ,redo load balancing

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3. APPENDIX A : LOAD-BALANCING AMONG (PUPES)

a) Distribute No. of COCs equally among all SMA-PUPEs (of course, taking care as far as possible that multiple COCs in one direction are spread across different TSVs for redundancy) b) Balance CICs by FLUMO during slack hours more or less equally after splitting large NFSCs greater than 512 and load share in routings ACH TYPE 11 with DIS= NT1.Splitting routing codes to the original large nfsc and sub-Code-wise routing to individual split NFSCs can also be adopted. Minimize overflow routings. c) From the busy hr OCHLA find summation(FPA+FPD) and summation(FOA+FOD) over all NFSCs PUPE-wise based on FLUIL in (b). d) Run OCAGE during busy hr for about 20 minutes-- ( it is safe).

OCAGE: AM=SMA1+SMA2+SMA3+SMA4+SMA5+SMA6+SMA7+SMA8,T=20; OCAGE: AM=SMA9+SMA10+SMA11+SMA12+SMA13+SMA14+SMA15,T=20; e) From (d) calculate [TOML X RTCML] / summation over all pupes{TOML X RTCML}. The difference in value calculated for each PUPE must be kept less than 10%. Load modification could occur as a defence mechanism if TOMLxRTCML/100 exceeds 80. f) Make FLUMO for more heavily loaded SMAs again based on higher FPA+FPD to less loaded PUPEs. g) If STP overload messages are observed for a PUPE (TSM will be indicated in such messages), identify COCs used for STP traffic(ie, mobile operators, SCP), and shift to less loaded SMAs as identified by (e). OCIN: CTO=TTRA- +TREF- ; taken periodically during busy hour will help identify PUPEs with heavier volume of STP traffic-counters indicate successful and rejected MSUs respectively.. TTRA-15+TREF-15 gives the summation over all PUPEs. h) Run 2-3 iterations of steps (c) to (g) to get best results. I) If PUPEs collapse at times with locavar passing, FLUMO for 2 NFSCs at a time to another PUPE can be done to identify troubling NFSCs.Check if erlang traffic is over 90%---(FOA+FOD)/FS. Look in such cases also for ETU breakdown alarms, and repair.Put SARLA on any 4 circuits , and send the messages after busy hour to TAC, along with SRFIL,dbg=h'1': DD= <start date>, HD=<start time>; and the output of PFSI,PFID PFIM

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plus ANOIL:DD= <start date>, HD=<start time>;. Keeping the standby PUPE INDL-BLOM, then completing a cycle of BLOM--> ES with REG=CDP for all affected PUPEs could also clear the problem(Note: with standby in BLOM, the other PUPES have to be made BLOM directly---INDL is not authorised)---this will prevent accumulated faults from switching to the current standby.

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ITI LIMITED

TIPS FOR IMPROVING CCR IN OCB283 EXCHANGES Congestion on routes, Subscriber behavior, Over loading, Network congestion, Ratio of CCS7 and R2 circuit, Faulty hardware, Transmission failures are normally the reasons for low CCR in the switch. From maintenance point of view subscriber behavior (incorrect dialing/incomplete dialing/on hook before answer etc) can not be controlled. The main observation in OCB is based on OCHLA and the parameter meanings are explained in the ADES documentation (OBRECOCB). 01.

Find out the congested circuit groups and increase the number of circuit. The circuit load should not exceed 0.7 E. It is better to target with a load of 0.6E as a steady state load in Normal busy hours. This will take care of unexpected traffic peaks.

02.

Evenly distribute the load among the PUPE s to have a better load distribution. Check SRFIL for any load modification in PUPE.

03.

CCS7 resources are to be loaded with in the dimensioned capacity and may give a margin of 10% to take care unexpected traffic peaks.

04.

As far as possible give higher depth of analysis in local exchanges to avoid the cases of wrong dialing /incomplete dialing reaching tax exchanges.

05.

In order to avoid unnecessarily a high number of repeated rout selections in Type11 ACH’s the value of number of retrials (NT) should be one.

06.

In CCS7 routes the RCR should be kept maximum to reduce the SAM’s. Also maximize the RCA to reduce the load in MR /TR.

07.

Large number of both way trunk groups can be split in to two or more small groups (with a maximum limit of 512 cics). Routing levels can be split among these trunk groups.

08.

Try to pre collect CLI on incoming R2 (by putting DP7) to reduce CLI request messages in outgoing CCS7.

09.

Use FINU parameter (End of called number) in originating local exchanges to avoid unnecessary waiting for more number of digits.

10.

Use correct law on both sides of CCS7 links to reduce collisions.

11.

In order to balance the signaling traffic on COC’s use proper laws. For example use law 23 for FSM with 5,6 or 7 COC’s, law 31 for 8 COC’s, law 7 for 3 COC’s, law 8 for 4 COC’s etc.

12.

Balancing of load in PUPE is also important to distribute the load in SMA. Standardize the NFSM and ASM laws. Check the load with SCSLA.

13.

Avoid 3rd 5th and 9th COC’s since load shared by them are high.

ITI LIMITED

14.

Attend to OFSUT messages.

15.

OCAGE for all SMA’s and make sure that TOML x RCTML is within 5% of average. OCIN: CTO=TTRA1<14+TREF1<14; distribute STP massages.

16.

Distribute the COC equally among all SMA. Care may be taken to spread the COC’s in one direction in different TSV’s (This will give more redundancy).

17.

Try to reduce ineffective calls. Proper announcement for DNP, PG, Network failure, etc. Specific announcements can be fed, instead of acceptance tone, congestion tone, etc. e.g. for wrong SRC (REN 59), Password jammed (60), call from SR4 sub (116).

18.

Split NFSC as OG & IC if PRS1 (double seizure) is more; or, change NFSC LAW.

19.

Spurt in traffic due to Phone-in programme, Tele-voting, etc. Use proper filtering.

20.

To avoid overloading of CSN due to call-centre numbers connected on PRI, trunks can be extended from SMT.

21.

Use OTFLA to find trunk culprits (some calls may be failing through few trunks).

22.

Try to feed announcements without pip pip tone. This will avoid repeat calls and reduce the circuit holding time.

23.

Avoid too many ACD’s in the network.

24.

Run ORILA to find out call failure due to non availability of path (Heavy calls).Use ESALA to introduce call gaping. This will improve the CCR to a large extent.

25.

Another important point is the routine maintenance. a) Check daily SRFIL, ETTIL b) Change reserve SMA daily to update the CIC status. c) Clear SMX problems and do LOCAVAR of SMX periodically. d) Attend PCM alarms / LRI issues (If LRI 0 and 2 is in BLOS keep the LRI cable /create LRI 1and 3 with additional cables) e) Change reserve SMC weekly. f) Give CTIBSC fortnightly.