Download - DCR optimization after swap.doc
-
7/27/2019 DCR optimization after swap.doc
1/6
How to Improve Call drop rate
Background:in swap project,after swap there were some cells with
worse dcr,in order to improve this kpi,We summarized these aspects and gave
some suggestions:
1 Hardware problem
1.1check the alarm and history alarm,normally it can lead to call drops
due to Equipment Failure.
1.2 reset the site,If there are some call drops due to Equipment Failure
without alarm,maybe there are something wrong with our BTS software.reset
the site with level 4 during night.if also not ok,get the help from BSC guy.
1.3 check the WSWR of the site through MML,if the value of VSWR is
bigger than 1.5,maybe there are something wrong with feeder,TMA,or
antenna and so on.let site enginner go to this site with site master for testing
the VSWR.
2013-8-14 1 , 6
-
7/27/2019 DCR optimization after swap.doc
2/6
-
7/27/2019 DCR optimization after swap.doc
3/6
2 DRFU (PBT) Single Feeder(1TX+2RX)
2.3 Neighbors Relationship,we can use Nastar to check the
neighbors,especially missing neighbors.
2013-8-14 3 , 6
-
7/27/2019 DCR optimization after swap.doc
4/6
2.4 Frequency HSN MAIO and so on.
3 DATA CONFIGURATION
3.1 Coverage Parameters
About this kind problem,firstly we can collect the Measurement from M2000:
Number of MRs based on TA per TRX
Radio Link Failure Measurement per TRX
Radio Link Failure Measurement based on TA per TRX
Receive Quality Measurement per TRX
TCHF Receive Level Measurement per TRX
TCHH Receive Level Measurement per TRX
Uplink-and-Downlink Balance Measurement per TRX
After we anlyzed the report,we can know about the Receive Quality,Level,TA
and so on.if the TA is big for coverage plan,we should control the
coverage.parameters we can adjust as below:
a. RACH Min.Access Level(dbm),default value is -115,recommended value
-109.
b. Random Access Error Threshold, default value is 180, recommendedvalue 220
2013-8-14 4 , 6
-
7/27/2019 DCR optimization after swap.doc
5/6
c. RXLEV_ACCESS_MIN, default value is 8, recommended value 10.
d. otherwise,we can adjust downtilt and power to control the coverage.
3.2 Interference Parameters
About this kind of problem,we can collect the Measurement from M2000:
Radio Link Failure Measurement per TRX
Receive Quality Measurement per TRX
TCHF Receive Level Measurement per TRX
TCHH Receive Level Measurement per TRX
GSM Cell to GSM Cell Outgoing Handover Measurement
Interference Band Measurement per TRX
After anlysis,if there are high receive level with bad quality,a lot of quality
handovers and interference band are bigger than 3,there maybe
interference,we can adjusted the parameters as below:
a. Radio Link Timeout(SACCH period (480ms)) this parameter is about
downlink, default value is 16, recommended value 52
b. SACCH Multi-Frames(SACCH period (480ms)) this parameter is about
uplink, default value is 18, recommended value 36.
c. T200 FACCH/F(5ms) default value is 50,recommended value 80.
d. T200 FACCH/H(5ms) default value is 50,recommended value 80.e. N200 of FACCH/Half rate, default value is 29,recommended value 50.
f. N200 of FACCH/Full rate, default value is 34,recommended value 50.
g. if there is strong interference through monitoring channel interference
band,we need eliminate it.
3.3 Handover Parameters
About this kind of problem,we can collect the Measurement from M2000:
Incoming Internal Inter-Cell Handover Measurement per Cell
Outgoing Internal Inter-Cell Handover Measurement per Cell
Incoming External Inter-Cell Handover Measurement per Cell
Outgoing External Inter-Cell Handover Measurement per Cell
GSM Cell to GSM Cell Outgoing Handover Measurement
After anlysis,if there is bad hsr between 2 neighbors,and also Cell Outgoing
Handover Fail Reconn Fail happens,we need adjust some handover
parameters as below:
a. Edge HO UL RX_LEV Threshold,default value is 10,recommended value
15.
b. Edge HO DL RX_LEV Threshold,default value is 19,recommended value
2013-8-14 5 , 6
-
7/27/2019 DCR optimization after swap.doc
6/6
25.
c. Min DL Power on HO Candidate Cell,default value is 10,recommended
value 0.
d. Min UP Power on HO Candidate Cell,default value is 10,recommendedvalue 0.
e. Min Interval for Consecutive HOs,default value is 4,recommended value
2.
f. Min Interval for Emerg.HOs,default value is 4,recommended value 2.
g. Filter Length for TCH Level,default value is 6,recommended value 3.
h. Filter Length for TCH Qual,default value is 6,recommended value 3.
i. DL Qual. Threshold,default value is 55,recommended value 40.
j. UL Qual. Threshold,default value is 55,recommended value 40.
k. MR.Preprocessing, default value is YES,recommended value NO.
About the values of parameters,just recommended,you can decide to choose
according to actual situation, detailed meaning of these parameters,you can
get it from LMT help document,thanks,
2013-8-14 6 , 6