brighton 3goverview final
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8/12/2019 Brighton 3GOverview Final
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RF Partnership
BrightonOptimisation
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RF Partnership
3G Evaluation for Brighton-Driven on 05-MAY-2006
Summary
A Dual Mode Drive Survey performed over 1 - 5 May 2006 in Brighton, collected log files showing the following:
3 DroppedCalls0 Blocked CallsAll the drops were in residential areas. Coverage throughout the CBD was good.
The 1stdropwas due to overshooting of cells D57791 and D35062 located on the opposite side of the bay and addedincorrectly as neighbours to the cell G00882. The TEMS mobile handed into a foreign cell and had no relationship to return to
the original server. It is recommended that the overshooting cells be down tilted from 0 > 6deg and removed as neighbours to
the serving cell G00882.
The 2nddropappears to have been due to interference as RxQ was poor in spite of RxSS being good. The source of thisinterference only seem to be over a small area in which the TEMS mobile happened to be travelling very slowly, causing the
downlink RLT timer to elapse after 24 SACCH frames.The source of the interference cannot be traced yet, but a freq retune of
the server might resolve the issue. The drop rate of the server is only about 0.4%, insinuating that most of the traffic either dont
use that route or travel at sufficient speed to prevent RLT timeout. It is also suggested that the target neighbour G11931 be
uptilted by 2deg in order to increase the measurement window in favour of the target neighbour, prior to handover.
The 3rddropwas caused by a combination of crossed feeders between cells G32141 and G32143, and a clash of BCCHfrequencies between G11942 and G32141. This drop should be fixed by retuning either of the mentioned cells BCCHs, and by
investigating and if necessary, repairing site G3214s crossed feeders.
About 3003G and 2G neighbour additionshave been requested. Their handover stats will be analysed after a two weekperiod after which a neighbour culling exercise will follow, deleting unused neighbours and speeding up handover processes.
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Light Grey Demarcated Area = Populated AreasDark Grey Area RED Polygon) = CBD
Live 3G Sites
Central Business Area
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Light Grey Demarcated Area = Populated AreasDark Grey Area RED Polygon) = CBD
Upcoming 3G Sites
Central Business Area
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Light Grey Demarcated Area = Populated AreasDark Grey Area RED Polygon) = CBD
Live 2G Sites
Central Business Area
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Light Grey Demarcated Area = Populated AreasDark Grey Area RED Polygon) = CBD
Upcoming 2G Sites
Central Business Area
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1stPart of Dual Mode Drive Survey showing RSCP
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2ndPart of Dual Mode Drive Survey showing RSCP
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3rdPart of Dual Mode Drive Survey showing RSCP
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4thPart of Dual Mode Drive Survey showing RSCP
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Predicted 3G RSCP Coverage
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Predicted 3G EcNo Coverage
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Predicted 2G RxSS Coverage
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Predicted 2G RxQ Coverage
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Serving Cell
1sthand over to site G5779with ET=0 and MT=0 7
2nd hand over to site G35062 withET=0 and MT=0
Analysis of 1stDropped Call
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Analysis:
Drop call was encountered in this region when the serving cell G00882handed over to a neighbour cell,
D57791, being nearly 20kms away.
The call was then handed to D350621,which was even further away, but had no neighbour relationship
back to the original server, G00882.
GSM sites D35062 and D57791 have 0deg electrical and mechanical tilt andfaces the bay, which
increases their propagation capability over a much longer distance.
Solution:
Delete Ncell D57791 as a neighbour to the site G00882
Mechanically down tilt cell D350621 and D57791 to 6deg
Analysis of 1stDropped Call
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Sector ID BSIC UARFCN Comments Category Log file Date TimestampG00882 60 83 Serving Active
NodeDeletion ofNcell relation
defined too far
0427_03.log 05 May2006.
15:26:38
D57791 42 551 1stsuccessful
handover, site has
ET and MT=0
Antenna Tilt
change
0427_03.log 05 May
2006.
15:26:38
G350621 53 559 2ndhand over, site
is over shooting
along the coast
and the site has
ET and MT=0
Antenna Tilt
Change
0427_03.log 05 May
2006.
15:26:38
Analysis of 1stDropped Call
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Site 1193
Area of drop
Area of Call drop
Analysis of 2ndDropped Call
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RxQual of the signal is
very low in this region,
due to interference
Area of call drop
Analysis of 2ndDropped Call
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Cell ID BSIC UARFCN Comments Category Log file Date TimestampG11931 53 93 Site has a down tilt of
4 at the moment
Antenna Tilt
Change
0427_17.log 05 May
2006,
15:26:50
Analysis:Serving cell G57873 has good signal strength at the drop location, but poor RxQ.
90% of the receiving neighbour cells (G11931) footprint is elevated above ground level, yet thecell has a down tilt of 4deg. A mechanical up tilt of -2deg might help to increase the neighbours
RxSS thereby allowing for a longer neighbour measurement window and possibly sufficient time
for handover.
Drop call rate for the serving cell is 0.4%, suggesting a low impact from the RxQ problem.
Solution:Recommend freq retune of G57873 and an uptilt of G11931
Analysis of 2ndDropped Call
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Area of Call drop
Site G1194 withBCCH=85
Cell G321431 withBCCH=85
Area of drop
Analysis of 3rdDropped Call
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Analysis:
RxSS deteriorates due to the TEMS mobile losing line of sight with serving cell G32143
Co-sector G32141BCCH (85) is measured as being a possible candidate for handover. However, a
faraway cell G11942has clear line of sight to the mobile and also has the same BCCH.
Presumably the mobile experienced sufficient interference from the similar BCCH freqs and incorrectly
decodes the BSICs, causing it to incorrectly handover to the co-sector G32141.
It is also suspected that the co-sector neighbour and the serving cell (G32143 and G32141) have cross
feeders as it is quite unusual for a co-sector pointing 120deg away from the serving co-sector, to be
received by the mobile as having a comparable signal level, in spite of the mobile being more then 1kmaway.
Solution:
Successful handover and call completion could be attained by retuning the frequencies of either of the
sites G32141 and site G11942
The possibility of cross feeders between cells G32143 and G32141 will be investigated and the situation
rectified if necessary
Analysis of 3rdDropped Call
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Sector ID BSIC UARFCN Comments Category Log file Date TimestampG32143 52 73 Serving Active
Node
0428_20.log 05 May
2006
15:26:02
G32141 43 85 Handover to
Frequency 85
which is the co-
sector site
Possible
Crossed
Feeder
0428_20.log 05 May
2006
15:26:02
G11942 33 85 Server should
have handed
over to this site
for successful
call completion
Possible
Crossed
Feeder
0428_20.log 05 May
2006
15:26:02
Analysis of 3rdDropped Call
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Rscp and EcNo Distribution over the 1stQuarter of the Route
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Rscp and EcNo Distribution over the 3rdQuarter of the Route
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Rscp and EcNo Distribution over the Last Quarter of the Route
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Antenna Tilt Changes
Recommendations
Cell ID ExistingElectrical Tilt ExistingMechanical Tilt Total ProposedElectrical Tilt ProposedMechanical Tilt Total Comments
D57791 0 0 0 0 6 6 6 degrees
mechanical down tiltD350621 0 0 0 0 6 6 6 degrees
mechanical down tilt
G11931 0 4 4 0 -2 2 2 degrees
mechanical up tilt
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