Transcript DRIVE TEST WORKSHOP - ITS

GSM Cell Planning and Optimization
Study Case : Sragen Area
By Sumantri Pramudiyanto (+6281703544310)
Jakarta, April 7th , 2009
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Content
 Cell Planning Process
 Idle Mode Operation
 BSS Parameter
 RF Optimization flow chart
 Study Cases of RF Optimization
Cell Planning Process
 Cell planning can be described briefly as all the activities involved in determining
which sites will be used for the radio equipment, which equipment will be used and
how the equipment will be configured
Traffic and coverage Analysis
 Collecting required data
 Making discussion with the client to know their demand.
 Analyzing traffic and coverage
Required data :
• Geography data
• Demography data
• Data of around network
• Available frequency
• Number of customer which
wish to cover
Customer demand :
• GOS 2%
• 95 % Indoor coverage
• (C/I > 12 db) > 95%
Nominal Cell Plan - Dimensioning (1)
Geography and Demography data taken from sragen.go.id
Table 1 Geographic + Demographic data
Table 2 Demographic data per years
Target subscriber
• After the data available, we need to divided the region into
smaller cluster, then classify the subdistrict into cluster
depend on traffic, contour area, and etc.
• From the demographic data (Table 2) , we able to calculate
% growth of population.
Pt  Po (1  r )n
573333 = 437556 x (1+r)6
r = 0.046
• Assume that, in 2010 the operator want to cover 10 %
subscriber in the region, so the number of subscribers to be
covered :
Pt = 10 % x 57333 x (1+0.046)3
Pt = 65629
• If traffic allocation per subscriber equal to 60mE then total
traffic in Sragen area = 65629 x 60 mE = 3937.74 E
Wide of area which will be covered
Nominal Cell Plan - Dimensioning (2)
 From the geographic data we can determine Erlang distribution by density in each
cluster.
 The next step, we can calculate the number of required sites depend on traffic.
 Using erlang B table we can count number of sites for cluster sragen tengah (GOS 2%, 1585.85
Erlang)  1586 TS ~ 227 TRX
 Sragen tengah locate in center of town and has high traffic we use configuration 5/5/5 so the
number of sites required in this cluster :
227/15 TRX = 15 Sites
 With the same way we can calculate number of sites for the others cluster:
Sragen Timur = 9 sites
(Config 4/4/4)
Sragen Barat = 12 sites
(Config 4/4/4)
Sragen Utara = 9 sites
(Config 4/4/4)
Nominal Cell Plan – Link Budget
 Link Budget Calculation is required to achieve system balance between uplink and downlink
signal.
 Output from system balance is a cell size in every sites.
 We can calculate coverage area per sites in suburban and rural cluster by equation L = k x R2
Lsite suburban
= 1.95 x (1.865)2 = 6.78 km2
L site rural
= 1.95 x (2.67)2 = 13.90 km2
 The next step, calculating number of sites related to coverage.
Choose the biggest one
Nominal Cell Plan - Result
Sragen Utara
Sragen Timur
Sragen Tengah
Sragen Barat
CW Test / Model Tuning
 In order to find out appropriate
propagation model, RF Engineer should
perform CW Test.
 Drivetesting should be performed
encircle the route and represent all of
azimuth.
 Input all of drivetesting result to the
planning tools then conducting calibration
to get appropriate propagation model.
Survey
 Survey is required to ensure whether the nominal cell position can
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be realized or not ?
In general, The RF Team should give alternative nominal or informed
SAR ( ± 300m) to survey team, in case the nominal cannot be
realized.
The survey team should take the panoramic photo around the
nominal (0-360 degree), and report to the RF team if appear
obstacle around the nominal.
Panoramic photo used to determine coverage target/azimuth
Survey team also need to survey : road to nominal, electricity, space
for equipment.
Detail Planning
 All of nominal coordinates must be fixed in detail planning phase.
 Scope of works in Detail Planning :
 Frequency Planning
 Parameter Planning (BSIC, MAList, MAIO, HSN, etc)
 Adjacency planning
 The main key in conducting frequency planning is avoiding co-
channel and adjacent interference.
 For TCH Frequency planning, we able to apply SFH or Baseband
hopping in order to reduce the interference.
Detail Planning – Frequencies Allocation
 SFH Pattern 1x1 will be applied in this implementation
 Number of Malist frequencies can be calculated by using equation :
 Maximum configuration for the sites 5/5/5, so that number of required
frequencies :
Nfreqs/site = (12 – 3 ) x 2 + 3.2 = 24 Frequencies
NTRX
FL =
X 100%
# Hoppers
3 sectors with 24 hopping frequencies :
-TCH = 3 TRXs  FL = (3/24)*100% = 12,5%
-TCH = 4 TRXs  FL = (4/24)*100% = 16,67%
Detail Planning – Frequencies Allocation
SFH Allocation untill configuration 5/5/5
MAIO
MAIO Step
= 0
= 2
8
16
Detail Planning – HSN Planning
 HSN used to the parameter that differentiates the hopping algorithm
between two cells having the same MAList.
 We can choose best pairs HSN to reduce collision frequencies
between server and adjacent.
Drivetest for QOD Program.ppt / 24.04.2008 /
VS
Detail Planning – Coverage Result
NCC = 4,5
NCC = 5,6
NCC = 0,1
NCC = 2,3
Detail Planning – Interference Prediction
Installation and System Tuning
 After Installation done, the installation team need to conduct
commisioning (VSWR Measurement, check hardware installation )
 The Drive test team also need to verify whether the BTS serving
target correctly or not
 Then, Acceptance Test Procedure is conducted to check how well
the KPI meets the demand.
 Pre Launch Optimization performed to achieve the KPI Target for
new site or TRX expansion.
IDLE MODE OPERATION
Normal Cell Selection
Search all the RF channels , take samples during 3-5 s and
calculate averages. And put them in ascending order with respect to
signal level. Then tune to the strongest RF channel.
Search for the frequency correction burst in that
carrier in order to varify if it is a BCCH carrier
No
Is it a BCCH
carrier?
Yes
Try to synchronize to the carrier and read
the BCCH data.
No
Is it a correct
PLMN ?
Yes
Yes
Is the cell barred?
No
Is C1>0
Yes
Camp on the cell
No
Tune to the next highest
RF channel which is not
tried before
C1 = (A - Max(B,0))
A = Received Level Average p1
B = p2 - Maximum RF Output
Power of the Mobile Station
p1 = rxLevelAccessMin
Min. received level at the
MS required for access to
the system
p2 = msTxPowerMaxCCH Max.
Tx power level an MS may
use when accessing the
system
Cell Reselection
C1 + cellReselectOffset - temporaryOffset*H(penaltyTime-T)  T < = penaltyTime
C2 =
C1 + cellReselectOffset …………………………………………. T > penaltyTime
1 when T < = penaltyTime
H(x) =
0 when T > penaltyTime
Cell Reselection Histerysis
BSS Parameter
BTS Parameter
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RxLevAMI (0-63) Minimum signal strength for access the BTS in idle mode.
CRESOFF (Cell Reselection Offset) (0-25)  used for C2 Calculation, normally used in dual band network
(GSM<>DCS)
RACHBT (RACH Busy Threshold) (0-127) defines a threshold for the signal level on the RACH
HRACTT1 (0-100)  Half Rate Activation Threshold
T3212 (0-255)  Parameter LUP Periodically
MAXRETR (1,2,4,7)  Maximum Retransmission on RACH
SDCCHCONGTH (0-100)  SDCCH Congestion threshold
RDLNKTO (0-15)  Timer for Radiolink timeout
Power Control Parameter
 LOWTLEVD/U (0-63) the lower threshold of the received signal level on the downlink/uplink for power
increase
 UPTLEVU/D (0-63)  defines the upper threshold of the received signal level on the uplink/downlink for
power reduction
 LOWTQUAD/U (0-7) the lower threshold of the received signal quality on the downlink for power increase
 UPTQUAU/D (0-7) defines the upper threshold of the received signal quality on the uplink for power reduction
 PWRINCSS (DB 2,4,6) defines the step size used when increasing the MS transmit power
 PWREDSS (DB 2,4)  defines the step size used when reducing the MS transmit power
BSS Parameter (2)
Handover Parameter
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HOLTHLVDL/UL (0-63)  defines the receive signal level threshold on the downlink /uplink for inter-cell
level handover decision.
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HOLTHQUDL/UL (0-7)  defines the receive signal quality threshold on the downlink/uplink for intercell quality handover decision
Adjacent Parameter
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RXLEVMIN  the minimum received signal level the adjacent cell must provide to be regarded as a suitable
target cell for handover
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HOM  Handover margin for better cell
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LEVHOM  parameter defines the handover margin for handovers due to uplink level or downlink level
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QUALLEVHOM  this parameter defines the handover margin for handovers due to uplink quality or
downlink quality
RF Optimization Flow Chart
Start
Check
SDCCH
Blocking
Identify KPI
Formula
Check
TRX
Quality
Identify the problems
SDSR
Problems ?
Check
Alarm
Y
Check
Interference
Check
TCH
Blocking
Check Alarm
Check cochannel and
co-BSIC
Check
Interference
Check TA
HOSR
Problems ?
DCR Problems
Y
Check all others
cause (Radio link
Failure, T200,
Transcoder) from
statistics
Check
Neighbor
Relation
Check
Handover
Failure Per
Cause
Check
Handover
Parameter
Check
TRX
Quality
Check Alarm
Check cochannel and
co-BSIC
Check
Interference
problems
Check Malist,
MAIO and
HSN
Check
measurement
from statistics
Take Action
list
Conclusion
 Every New Network need good plan for avoid problems that
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will be arise.
Commonly there are six step in conducting planning.
The most critical problems in performing cell planning
process is interference.
the New Sites onair need to be optimized to achieve the KPI
Pre Launch Optimization is done for new sites on air or
expansion sites.