Banglalink GSM Optimization Project

Bangalink Optimizer TrialFix monster BSC in 2 weeks

Matti PuhtoNSN/Global Services/Managed Services/Network Planning and Optimisation/Expertise LeverageRiku ErtimoNSN/North East/Managed Services/Network Planning and Optimisation

FEB-12

2 © Nokia Siemens Networks Network performance / Matti Puhto / FEB-12

Scope

To show power of Optimizer tool for one big BSC and spend max 2 weeks for all this• Optimizer is a tool which makes best possible frequency plan• This frequency plan is based on actual interference matrix in the network• This is extremely fast and efficient way to optimise network• Good quality gives possibility for other capasity features (like Orthogonal SubChannel, OSC)

One BSC was selected• 8 million calls per day• 124 kErlangs TCH traffic• Dropped Call Rate DCR_3i: 1.43 (24 hrs)• DL Quality good classes 0…4: 93.93% (24hrs)• Total SDCCH drops SD_1a: 11.03% (24 hrs)

Expected results: new frequency plan should boost the following KPIs:• Good DL quality class 0…4: will go up• Droped Call Rate: will go down (focus to RF and HO drops)• SDCCH drops will go down (focus to SD A-bis and SD RF drops)


Time line

31JAN: measurements are running successfully• Total FEP –measurement activation• This is Frame Erasure Probability (what are changes to loose DL speech frame, C/I and FEP, BSC will do for each meas sample)• Create MBAL list into BSC (rotate ‘fake frequencyes’ which will force MS to all BCCH frequencyes, this is bases for interference

matrix)1FEB: 10AM arrival at Bangalink office• Interference matrix generation• Ncell additions/deletions• Hands-on discussion• Worst cell analysis• Implementing Ncell plan2FEB: 10AM arrival at Bangalink office• Frequency planning and ready for implementation• Hand-on discussion• Expected implementation 7FEB 3AM5FEB: Holiday6FEB: 10 AM arrival at Bangalink office• Worst cell recommendations7FEB: 10 AM arrival at Bangalink office• Frequency plan implemented• Performance analysis8FEB: Reporting• Final meeting in the afternoon 4PM-6PM


Optimizer: the data flow structure

Statistic DB

Optimizer

Data

Optimizer

Data

NetActtm

Optimizer CM

Data

CM

Data

CSVASCII

NMS

Conversion SW

Conversion

SW

NMS

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Vendor-Y

NSN

ADE

MV

PM

Data

PM

Data

IM Generation

- Existent Functionality

- Integration Project

- Operator Specific

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Configurator

Reporter

CSVXML

CSV

NMS

Site data base

Planningtool

NSN

MMR


Expected outcome of the new frequency plan ?

• The figures will tell how much quality will improve if the proposed frequency plan is implemented

• Figures are FEP changes

• Erlang distribution (BSGZ04 figures)• G900 34%• G1800 66%• 95% of BCCH are in G900 band (CBCCH widely in use)• Only 5% of segments are stand a lone G1800 BCCH

Band/Layer Avg Interference (%) CoCh Interference (%) AdjCh Interference (%)Network (Iteration 1) 0.6 0.3 0.3 GSM 900 0.74 0.4 0.34 BCCH 0.55 0.27 0.28 TCH 0.92 0.53 0.4 GSM 1800 0.33 0.12 0.21 BCCH 0.19 0.04 0.15 TCH 0.34 0.12 0.21Network (Actual) 3.19 1.42 1.79 GSM 900 2.85 1.63 1.24 BCCH 3.15 1.73 1.45 TCH 2.55 1.54 1.02 GSM 1800 3.85 1.02 2.86 BCCH 9.72 1.43 8.41 TCH 3.4 0.99 2.44Network (Delta) -2.59 -1.12 -1.49 GSM 900 -2.11 -1.23 -0.9 BCCH -2.6 -1.46 -1.17 TCH -1.63 -1.01 -0.62 GSM 1800 -3.52 -0.9 -2.65 BCCH -9.53 -1.39 -8.26 TCH -3.06 -0.87 -2.23


Step 1: Manipulate adjacencies

- Optimizer is proposing to add 378 new ADJ relationso This is based on measurement reports from MSo When MBAL rotation were used it results that new cellB is reported to

be strong and FEP should stronger than 1% (yes stronger, we have to take that frequencies are put in smart way)

o So strong FEP means good candidate ADJ pair

- Banglalink accept 61 of those- Banglalink reject 317 of those

o Those which were rejected are typically over shooting cellso An other possibility is: antenna azimution do not match in plan and in

realityo There is going to happen different kind of activity to verify and fix

those 317 cell pairso This is naturally really valuable info to detect over shooters and

potential antenna problems

- These went live 1FEB12 at 18:12

Optimizer is proposing to kill 515 neighbor relationso This is based on one week actual HO attempt in BSC BSGZ04o If one cell pair has zero HO att AB and zero HO att BA this existing

neighbor relation is proposed to be killed

- Banglalink accept 245- Banglalink reject 270 of those

o The argument: just to play safe

- These changes went live 1FEB12 at 18:31

Affect: • Average queuing time has gone a bit lover levels, but queuing is still very large• Direct retry attempts did rise, which is due to adding 61 ncells • Call volume up +3%• DCR_3i remains in 1.37% (Friday is the busiest day in this BSC, 27jan vs 3feb)


Step 2: Make new frequency plan

Separation violation penalties, important, how big is the crime

• Note: GSM1800 BCCH band (kill some frequencies)

• Current 265 violations total • First indicators will say: 4 violations

left• G900 band FEP effect: -2.01 • G1800 band FEP effect: -3.31• Total BSGZ04 effect: -2.45• Current traffic distribution

– G900 34% – G1800 66%

Expected result:• Really encouraging results• Better quality will provide change to

introduce new capacity features like OSC

• Since G1800 layer will be much better, it will also affect to HO distribution

• Example segment x1771 s2 and s5:– G900 DL qual0…4 85%, 4 Erl, 2TRX– G1800 OK qual, 36Erl, 4TRX– Now CBCCH is not working since G900

has bad qual, LSEG20%– Segment DCR now 0.35%, deep indoor

call must stay in bad G900 and this is not visible well in stat, this is a reason for customer complains

These figures are with:

No changes to current FH type


End of 1st week

• Our initial results (in Optimizer tool not in live network) are really encouraging• Current bet is: Drop Call Rate (not this is not official Bangalink formula) will go from 1.43 to

1.15 level, this translates 20% reductions to drops (now you must say laud: WOOOW !)• Also we expect to see very positive affect to quality. We have detected one example cell

(x1771s2 and s5), where KPIs look good, but 900 layer has terrible bad quality, the reason behind customer complains may be: fella is in deep indoor and therefore only 900 is available. This call has really bad quality and even a drop. There are some hundreds of this kind of calls per this cell, but those bad calls are not visible in stats since this cell carry some 35.000 calls. We expect that when frequency plan is good, it will reduce customer complains. This segment has 2 TRX in 900 and 4 in 1800 band

• We expect that we deliver only one new frequency plan, based on existing hopping strategies (BB and non hopping)

• We see Bangalink fellas Monday 2pm and we discuss how comfortable they are with new plan after discussion we have GO decision for this new frequency plan

• New frequency plan will be implemented Tue 7feb at 3am we start to get first results midday on Thu 7feb and those are going to be very good

• 8FEB afternoon we have final presentation what was happening during Optimizer trial in BSGZ04. We are proposing 4pm…6pm, Bangalink has not confirmed that


Quick results are implementing the frequency plan


Result: Dropped call rate improved (this is official Bangalink Formula)

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6-Feb-12 7-Feb-12

New frequency plan implemented 7feb at 2am

Result: DCR improved by 20%

Full day result

Old frequency plan New frequency plan


Result to SDCCH drops (this is official Bangalink Formula)

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6-Feb-12 7-Feb-12

New frequency plan implemented 7feb at 2am

Signaling drops improved 19%

Full day result



As expected: TCH Traffic has remain as same

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Full day result



Better Quality means less handovers due to quality reason

02.06.2012 02.07.20120

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DL Qual HO

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UL Qual HO

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Change -16%

Change -30%

Old frequency plan New frequency plan Old frequency plan New frequency plan


How quality improvement translates to extra Erlangs ?

Message: by improved quality we expect to carry 40% more OSC activities in BSGZ04!

• New frequency plan improve FEP 2.19% 0.60%

• This translates to

• 50% of the carried traffic has C/I ratio <16.5dB

• After the new frequency plan we see that 50% traffic has C/I ratio as 22.0dB or better

• For OSC (Orthogonal SubChannel) we need good quality, i.e. C/I requirement is 17dB

• It is estimated that:

• With old frequency plan we used to have only ~ 45% of Erl in C/I over 17dB

• With new frequency plan we have ~ 63% of traffic which is enjoying C/I over 17dB

• Practice has shown that OSC intake is in range of 30% on cell level

• This includes 60% SAIC capable MS penetration and C/I distribution

• OSC accessible market was: 30% of 45% = 13,5%

• OSC accessible market is now: 30% of 63% = 18,9% This is +40% more OSC activities with new frequency plan (and zero new TRX) This is +5% traffic increase without TRX expansions

Banglalink GSM Optimization Project

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