F3 on 3G Big Polluter Cells

VodafoneCompany Confidential27/04/2012 Luca Giuliani

F3 on 3G Big Polluter Cells

VodafoneCompany Confidential

Scope of the analysis

Just few big pilot polluters can decrease the performances of a single RNC

Following factors lead to difficulties to reduce the negative effect of polluters: No site access due to public reaction Site location on top of hills in urban clutter Antenna type Reflection/diffraction Backlobe overshooting

In RGAZH01 we have identified Top 10 polluters cells for which all the possible physical and power changes have been already implemented

UARFCN 10713 (F3) has been used for the polluters

F3 was implemented using CME in M2000

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N3502_01948_B2381_CengizhanMah

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Alsancak, Kordon Very big polluter, overshooting

toward Alsancak area CPICH limited to 24dBm Upper lobes of antenna

patterns are the main contributors to pollution

Due to public reaction, access to site is very hard


N3502_01593_A2464_TekstilcilerCami

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Very big polluter, overshooting toward Bornova area

CPICH limited to 23dBm Back lobes of antenna patterns

are main contributors to pollution

Back lobes suppression panel applied but still high pollution


N3502_01343_A2406_ZiyaGokalpCad, N3502_11676_B2604_BornovaAtaturkStar, N3502_11680_E4115_AtaturkTurgutReis

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Side and back lobe overshooting leads to huge polluted area


Problems after F3 implemented

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With F3 implemented, F1 layer becomes less polluted but cells on F3 showed larger footprint in terms of PRACH attempts

F3 is a very “clean” layer, therefore cells with F3 shows very good Ec/No much further than before

Even if there is no neighbor we can still see lots of PRACH access on F3 at larger distance than before

The reason for UE to camp on a cell which has no neighbor with other cells in the area is explained hereafter:

If the serving cell is not fulfilling the cell selection criteria S for Nserv consecutive DRX cycles (2*1.28s = 2.56s), the UE has to start measurements on all neighbouring cells (scan all PSC in every allowed UARFCN)

S criteria is: Qqualmin (Ec/No) = -18dB AND Qrxlevmin (RSCP) = -116dBm The Nserv is known by the UE with the DRX cycle length DRX cycle coefficient = 7 Default DRX cycle length = 27 radio frames = 1.28s From TS25.133, Nserv = 2 (mapping with DRX cycle length of 1.28s) The UE has to find a suitable cell within 12 seconds:

If it fails, and the UE is in the RRC idle mode, it initiates the cell selection procedures for the selected PLMN

If it fails to find a suitable cell within 12 seconds, and the UE is in the RRC connected states CELL_FACH, CELL_PCH or URA_PCH, it is considered to be “out of service area“


PRACH propagation and Ec/No

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PRACH in F1

PRACH in F3

PRACH in F3 with newS criteria settings

Moving from F1 to F3, the number of RRC doubled since F3 layer is very clean and Ec/No is much better

We set new S criteria settings in order to limit the camping to the cell:

Qqualmin (Ec/No) = -9dB Qrxlevmin (RSCP) = -99dBm

The graph at the bottom shows that with new S criteria settings we can confine the location of the PRACH (although the cell is still overshooting) and the Ec/No is better than -9dB

Higher settings can be applied (Qrxlevmin = -85dBm), but this can limit the indoor coverage in the area close to the cell

Qrxlevmin = -85dBm can also provide worst PS performances because when UE is in Cell-FACH/PCH, it could enter into “Out-of-service Area” starting T307; if UE can not find a suitable cell within T307 (30s) it moves into the idle mode and releases all resources


Voice Attempts – F3 cells

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Cells in F1 Cells in F3 Cells in F3With new S criteria

New S Criteria moves back to similar number the call attempts as in F1


RRC Establishment FR – F3 site

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New S Criteria limits the coverage of F3 cells and improves RRC establishment rate


Voice RRC Establishment FR - F3 site


New S Criteria limits the coverage of F3 cells and improves Voice RRC establishment rate

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PS Rab Establishment FR - F3 site

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New S Criteria limits the coverage of F3 cells and improves RAB establishment rate



Voice DCR - F3 site

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New S Criteria limits the coverage of F3 cells and improves RAB abnormal release rate


Effect of F3 on RNC RGAZH01 – PS Drop

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Polluter Cells in F1 Polluter Cells in F3 Polluter Cells in F3 with new S Criteria

15% improvement in PS Drop when moving Top10 Polluter cells to F3 In RGAZH01 total number of cells: 505 The effect of pollution is very clear after changing frequency


Effect of F3 on RNC RGAZH01 – Voice Drop

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8% improvement in AMR Drop when moving Top10 Polluter cells to F3


Effect of F3 on RNC RGAZH01 – Voice RAB Est FR

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5% improvement in AMR Rab FR when moving Top10 Polluter cells to F3 with new S Criteria


Cell Reselection settings for F3

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Default settings for cell reselection are: Sintrasearch=10dB; Sintersearch=8dB; SsearchRAT=4dB

With new S criteria (Qqualmin (Ec/No) = -9dB) the thresholds to start intra/inter/irat cell reselection would be:

Intrafreq cell reselection: Ec/No > Qqualmin+Sintrasearch = -9+10 = +1 dB Interfreq cell reselection: Ec/No > Qqualmin+Sintersearch = -9+8 = -1 dB InterRAT cell reselection: Ec/No > Qqualmin+SsearchRAT = -9+4 = -5 dB

Default settings are not suitable for new S criteria because there would be many cell reselection especially for inter-freq and inter-RAT

New settings moves back to normal the cell reselection procedure: Sintrasearch=2dB; Sintersearch=2dB; SsearchRAT=2dB

Default S criteriaNew S criteria with default Cell-resel thresholds

New S criteria with new Cell-resel thresholds

VodafoneCompany Confidential 17

Inter-frequency handover settings for F3 During drive test for F3 mobility verification we noticed that the default settings to trigger

compress mode from F3 to F1 handover were too low Default settings:

Inter-freq CS Measure Start Ec/No THD = -11dB Inter-freq CS Measure Stop Ec/No THD = -8dB Inter-freq CS Measure Start RSCP THD = -100dBm Inter-freq CS Measure Stop RSCP THD = -95dBm Inter-freq CS Target Frequency Trigger Ec/No THD = -8dB Inter-freq CS Target Frequency Trigger RSCP THD = -85dBm

Since F3 cells are very isolated the location of Event 2D were quite far from F3 cells and possible F3-F1 missing neighbors were present

Also, after Event 2D was triggered, Ec/No degraded very quickly without giving time for UE to perform F1 cells measurements

New optimized cell settings provided better inter-frequency performances: Inter-freq CS Measure Start Ec/No THD = -9dB Inter-freq CS Measure Stop Ec/No THD = -7dB Inter-freq CS Measure Start RSCP THD = -90dBm Inter-freq CS Measure Stop RSCP THD = -85dBm Inter-freq CS Target Frequency Trigger Ec/No THD = -12dB Inter-freq CS Target Frequency Trigger RSCP THD = -92dB


How to use CME

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Next slides show how to use CME to generate MML commands to update all the parameters when changing UARFCN

CME creates automatically scripts to be run in RNC and NodeB, it is very user friendly


How to use CME

Example: change frequency and all other neighbor parameters for 12591 in RGAZH01


How to use CME


How to use CME

Type then save and close


How to use CME


How to use CME

If you leave it ticked, it will open Script Executor in which you can run the scriptIf un-ticked, it will only save the script and you can ask NOC to run it


How to use CME

2 txt files, one to be run in NodeB and one in RNC sideFolder Fallback in case you want to revert back to F1

C:\Users\lgiuliani\Desktop\F3_Test_201204


Other MML commands New S Criteria and Cell Reselection settings for F3 cells:MOD UCELLSELRESEL: CELLID=XXXXX, QQUALMIN=-9, QRXLEVMIN=-49, IDLESINTRASEARCH=1,

IDLESINTERSEARCH=1, CONNSINTRASEARCH=1, CONNSINTERSEARCH=1, SSEARCHRAT=1;

New Interfrequency handover settings for F3 cells:ADD UCELLINTERFREQHOCOV:CELLID=XXXX, PRDREPORTINTERVAL=D500, HYSTFORPRDINTERFREQ=0,

TIMETOTRIGFORPRDINTERFREQ=0, INTERFREQCSTHD2DECN0=-9, INTERFREQCSTHD2FECN0=-7, INTERFREQCSTHD2DRSCP=-90, INTERFREQCSTHD2FRSCP=-85, INTERFREQR99PSTHD2DECN0=-15, INTERFREQHTHD2DECN0=-15, INTERFREQHTHD2FECN0=-12, INTERFREQR99PSTHD2FECN0=-12, INTERFREQHTHD2DRSCP=-110, INTERFREQR99PSTHD2DRSCP=-110, INTERFREQHTHD2FRSCP=-105, INTERFREQR99PSTHD2FRSCP=-105, TARGETFREQHTHDECN0=-14, TARGETFREQR99PSTHDECN0=-14, TARGETFREQHTHDRSCP=-109, TARGETFREQR99PSTHDRSCP=-109, USEDFREQHTHDECN0=-12, USEDFREQR99PSTHDECN0=-12, USEDFREQHTHDRSCP=-92, USEDFREQR99PSTHDRSCP=-92, INTERFREQREPORTMODE=PERIODICAL_REPORTING, INTERFREQFILTERCOEF=D3, HYSTFOR2D=0, HYSTFOR2F=0, WEIGHTFORUSEDFREQ=0, TIMETOTRIG2D=D320, TIMETOTRIG2F=D1280, TARGETFREQCSTHDECN0=-12, TARGETFREQCSTHDRSCP=-92, USEDFREQCSTHDECN0=-12, USEDFREQCSTHDRSCP=-92, INTERFREQMEASTIME=60, TIMETOINTERFREQHO=0;


Thank you.

F3 on 3G Big Polluter Cells

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