LTE KPI Optimization - A to Z Abiola.pptx

Ericsson Internal | 2015-02-18 | Page 1
LTE POST LAUNCH OPTIMIZATION
Problem cause, counter pegging,
solution
&
Case study
a-z step

All the radio network counters from the EnodeB (and RBS) are reported from one Managed Object (MO) Class.
TYPE OF COUNTERS
Counters are used to collect PM statistics Data. Different types of counters are used to collect observable data.
There are 9 different types of counters available:
1. Peg – A counter that is increased by 1 at each occurrence of a specific activity. Eg:- pmBadCovEvalReport
2. Gauge – A counter that can be increased or decreased depending on activity in the system. Eg:- pmPrbUsedDlCcch
3. Accumulator – A counter that is increased by the value of a sample. It indicates the total sum of all sample values taken during a certain
time. The name of an accumulator counter begins either with pmSum or pmSumOfSamp. Eg:-pmRrcConnLevSum
4. Scan – A counter that is increased by 1 each time the corresponding accumulator is increased. It indicates how many samples have been
read, and added to the related accumulator counter. A scan counter can therefore be considered a specific kind of peg counter. Due to these
types of counters, it is possible to get the average value of all samples by dividing the accumulator counter by the scan counter. The name of
a scan counter begins with pmSamples or pmNoofSamp. Eg:- pmRrcConnLevSamp
5. PDF – A list of range values. A value is sampled (read) periodically. If the value falls within a certain range, the range counter for that range
is increased. All range counter values are collected and stored in ROP file at the end of the each reporting period. For example, if SIR values
are split into three range : Range1 = [-11 dB to -4 dB], Range2 = [-4 dB to +4 dB], Range3 = [+4 dB to +20 dB], and a value is read every 3
minutes over a 15 minutes period (values = -10, -3, +5, +5, +6), then the three Range Counters are reported as RangeCounter1 = 1,
RangeCounter2 = 1, RangeCounter3 = 3. Eg:- pmRadioRecInterferencePwr
6. Discrete Distributed Measurements (DDM) – A series of values recorded during a reporting period. Each series of values may be one of
the following measurement types:
1. Accumulated over a measurement period and read at the end of each measurement period (a gauge or peg counter)
2. Averaged over the duration of a measurement period
3. Read at a specific time (the measurement time), within the measurement period (at a specific frame)
At the end of a series of consecutive measurement periods (the reporting period) all measurement values are collected and stored in a ROP
file. Eg:- if a SIR value is read every 3 minutes over a 15-minutes period (value = -10, -3, +5, +5, +6), then 5 DDM measurements are
reported as Meas1 = -10, Meas2 = -3, Meas3 = 5, Meas4 = 5, Meas5 = 6.
7. Calculated – A counter whose value is determined by other counters. The calculation is performed in the RANOS Statistics database. The
ROP files are opened in order to be transferred into the database and the calculations are made by the database itself during this process.
This means that these counters are not available when the Statistics Database is not present.
8. TrigACC – A counter whose value is the sum of all values accumulated during the ROP at the occurrence of the defined trigger.
9. TrigSCAN – A counter whose value is equal to the number of occurrences of any defined trigger during an ROP.

ACCESSIBILITY for the E-UTRAN is a measure of the ability of a user to obtain an E-RAB from the system.
The Initial E-RAB Establishment process can be divided into the following phases:
 RRC CONNECTION ESTABLISHMENT
 S1 SIGNALING CONNECTION ESTABLISHMENT
 INITIAL E-RAB ESTABLISHMENT OR E-RAB ADDITION

RRC CONNECTION ESTABLISHMENT
S1 SIGNALING CONNECTION ESTABLISHMENT

E-RAB SETUP
E-RAB ADDITION

1. Poor coverage
 Check inter site distance with neighbors site.
 Check value of pmBadCovEvalReport (if MCPC enabled, need to check pmCriticalBorderEvalReport). If this counter is pegging
high in respect to RRC attempts, then we can say that more number of UEs are falling in bad coverage.
 Check counter pmCriticalBorderEvalReport (this means there is no LTE coverage, and UE will do release with redirect_(RWR)
with any Technology) & pmRadioTbsPwrRestricted (If this counter is more (>70%), then for that sector, the UE is using more
power to reach EnodeB, in that case pdcchutil is also high)
 Change qrxlevmin (In Sprint the parameter value is changed from -120dBm to -110dBm), so as to discard bad coverage / cell
edge UEs.
2. Alarms
 Through OSS commands “alt” (Current / Active site alarms can be checked) & “lga <nd>” (n is an integer value) (Site alarms
present for n days can be checked)
3. High Load (High Traffic)
 Check pmRrcConnEstabFailHighLoad & pmRrcConnEstabFailOverload counters If any sector is having high traffic. These
counters could be high due to high traffic and impacting CFR.
 The command “ue print -admitted” is used to find the no. of UEs currently latched to the site sector-wise ROP-wise & the
counters “pmRrcConnMax (max)” & “pmRrcConnMax (sum)” are used to find out ‘max. active users/ day’ and ‘sum of all
active users/day’, respectively.
 Sometimes, due to MOs are not synchronized properly, pmRrcConnEstabFailOverload is pegged high. In this case, the
ServiceUnavailable (S1 Connection failure) alarm is observed in sites, even though RRC Conn Users remain to be same.
4. H/W issue (Hard Reset on site / RRU Replacement, if required)
 If RRUs are disabled, in that case “HW fault” alarm is observed in sites.
 Command “st . aux” shows that the operational state of the auxiliary unit/ RRUs is DISABLED.
 Command “lgd” is used to find out transmission issue of site.
CONTD.

5. High UL interference
 High UL N+I is impacting to all KPIs. UL NI values {-119 …….. -110 dBm} is considered to be good.
 The cause may be Internal Sources (Check Tx & Rx antenna ports, fiber cables and connectors. All connection should be
proper) and External Sources ( like repeaters, airport, power plant etc. sources resulting in high EMW in the neighborhood).
 pmRadiorecInterferencePwr is checked for UL N+I values.
 Use pmr -m 72 -r 6 -f | egrep -i 'Interference|Res_AvgNrOfRrcConnectedUsers’ command to find out ROP-wise UL NI status of
last 72 hours, along with corresponding no. of average users.
6. PCI conflict
 Two types of PCI conflict:
 PCI confusion, i.e., UE is confused if it is getting two or more target cells having same PCI.
 PCI collision, i.e., UE is collision due to source and target having same PCI.
 Impacts all KPIs.
 Use “EUtranCellFDD . pciconflict” to find out PCI conflict of site.
7. RACH Root Sequence Index plan need to be reviewed
 Based on ‘Zero Correlation Zero Configuration‘ parameter RACH root Sequence index need to be planned. For Ncs = 12,
difference of 10 is recommended for RACH root Sequence index per cell.
8. UE camping in the wrong cell. Cell Reselection Parameters need to be tuned
 When UE is doing cell reselection if priorities are wrongly defined, in that case, UE will connect with wrong technology.
 In Sprint, cell reselection priority are defined based on capacity and technology whose range varies {0 .. 7} ( cell reselection
priority for LTE 2.5GHz is 7, LTE1900 is 5, LTE800 is 4, CDMA2000 is 2 and CDMA20001xRtt is 0)
 The command cellreselectionpriority is used to find out technology-wise priority for cell re-selection.
9. Wrong System constant setting(SC-556)
 We can set SC-556 from 10, 25, 35 & 45, based on traffic.
10. VSWR over threshold
 The cabx command provides VSWR status for RL1 & RL2 (for 2T2R). Both, RL1 and RL2 should be more than 14 with a
difference of less than 5.
11. Cell availability
 Cell availability should be 100%, if availability is less than 100%, then the site might be having transmission issue and also, the
site may not be taking traffic.

SSSR Phase based on Counter
1. RRC Setup: - The counters responsible are as follows
 pmRrcConnEstabAtt.
 pmRrcConnEstabAttReAtt
 pmRrcConnEstabSucc
1. S1-Signalling Setup: - The counters responsible are as follows
 pmS1SigConnEstabAtt.
 pmS1SigConnEstabSucc
3. E-RAB Establishment: - The counters responsible are as follows
 pmErabEstabAttInit
 pmErabEstabSuccInit
 pmErabEstabAttAdded
 pmErabEstabSuccAdded

1. Failure at RRC Setup Stage : pmRrcConnEstabFail is to be checked.
pmRrcConnEstabFail contributes to poor RRC Setup Success Rate. The triggering issues for pmRrcConnEstabFail are as follows : -
1. pmRrcConnEstabFailLic: The total number of failed RRC Connection establishments due to lack of connected users license.
Probable Solutions:-
 Upgrade the LKF (License Key File) by Upgrading Software. E.g.- From L12A to L12B and L13A to L13B.L14A having License of 2000 Connected user per
EnodeB. (License/Software up-gradation activity governs as per the agreement with customer).
Current licenseCapacityConnectedUsers as per WLA for Sprint is 100 Users per site.
 Offload the traffic by optimizing azimuth and tilt of the serving and neighbouring cells.
 By changing qRxLevMin (Default Value -120dBm); can be modified to -110 dBm
 By implementing Hi-Cap Parameter, if Max RRC Conn Users is more than 150/sector and pdcchutil>70%. Detailed parameters for Hi-Cap parameter
implementation have been shared later
 If traffic load is still high after implementation of above solutions, plan for new site to offload or change LKF from 1000 to 2000. (L12A- ;L12B-; L13A-;
L13B-L14A ) is submitted.
2. pmRrcConnEstabFailHighLoad: The total number of failed RRC Connection Establishments due to high load.
Probable Solutions: - Same as above.
3. pmRrcConnEstabFailOverload: The total number of failed RRC Connection Establishments due to overload.
4. pmRrcConnEstabFailActiveUserLicenseExceeded: The number of failed RRC establishments due to more active users than what license allows.
Probable Solutions: -
 Check Active user per cell through counter pmActiveUserDlSum, pmActiveUserUlsum.
 Try to offload traffic, if possible, by changing Azimuth/ Tilt or Loading Hi-Cap parameter or Load Sharing (In Sprint traffic load sharing b/w LTE1900 &
LTE800 co-located site is activated).
 Check distance of UE from EnodeB. If UE is connected to far away EnodeB, RxlevAccmin parameter can be changed to protect access.
 If Enhanced cell ID feature is enabled in N/W Timing Advance, then pmTimingAdvance counter can be used to check the TA value.
5. pmRrcConnEstabFailFailureInRadioProcedure: The number of failed RRC establishments due to failed radio procedure.
CONTD.

6. pmRrcConnEstabFailBearerAdmissionRej: The total number of failed establishment of RRC Connection due to the fact that all the UE's
bearers are rejected during bearer admission control.
 Implement Hi-Cap Parameter to allow more users.
 Also PDCCH Admission control Threshold can be changed. Before modifying this parameter, PDCCH CCE Utilization need to be checked via the counter-
pmPdcchCceUtil (it should be more than 70%)
7. pmRrcConnReestFailLicMtReest: The number of RRC Connection Reestablishments attempts that failed due to feature "Multi-Target RRC
Connection Reestablishment" not being enabled.
Probable Solutions: - Not included in any predefined scanner. So you have to activate Scanner.
8. pmRrcConnEstabFailLackOfResources: The number of failed RRC establishments due to lack of resources.
 Check the cell utilization and try to offload by Implementing Hi-Cap Parameter; shift traffic on the less utilized cells using tilt and load balancing feature.
9. pmRrcConnEstabFailUnspecified: The number of failed RRC establishments due to unspecified cause.
Probable Solutions: - Not included in any predefined scanner. So you have to activate Scanner.
CONTD.

2. Failure at S1-Signalling Setup Stage : pmS1SigConnEstabFail is to be checked.
Following issues could be the reason for having high pmS1SigConnEstabFail which contributes to have poor S1
Signalling Success Rate%.
1. TN (Transport Network Issue): Check Fiber Issue from IPBH Team.
2. Wrongly Configured TAC: Configure Correct TAC as per Design ( Pre-RNDCIQ).
3. LAC-TAC mapping: Validate if LAC-TAC mapping is correct as per Design ( Pre-RNDCIQ). Incorrect or missing TAI-
LAI pairing could result in ‘Accessibility Failures‘ when UE attempts CS Fallback to UMTS (LTE Attach Request of
type “Combined EPS/IMSI Attach”). The MME derives the LAI from the TAI of the current LTE cell, then MME
sends the “Location Update Request” to the target MSC/VLR.
CONTD.

3. Failure at Initial E-RAB Establishment Stage :
Following counters are suggested to be checked.
1. pmErabEstabFailGbrDlEnb: The total number of failed E-RAB setup attempts due to downlink GBR overload for resources common to the
EnodeB.
 Parameters that are required to be set are : dlNonGbrRatio(750) / dlTransNwBandwidth(1000).
2. pmErabEstabFailGbrUlEnb: The total number of failed E-RAB setup attempts due to uplink GBR overload for resources common to the
EnodeB.
 Parameters that are required to be set are : ulNonGbrRatio(750) / ulTransNwBandwidth(1000).
3. pmErabEstabFailAddedLic: The total number of failed establishment of added E-RABs due to license rejects (Multiple Radio Bearer per user
or RLC UM). Added E-RABs are all E-RABs present in S1 message E-RAB Setup Request.
4. pmErabEstabFailInitLic: The total number of failed establishment of initial E-RABs due to license rejects (Multiple Radio Bearer per user or
RLC UM). Initial E-RABs are all E-RABs present in the S1 message Initial Context Setup Request.
Apart from the above mentioned counters, following issues are suggested to be checked:
1. Security update Fail.
2. Vendor specific issue.
3. TN(Transport issue).
NOTE: Couple of CASE STUDIES are shared in the subsequent slides detailing parameter / counter level implementations that are
undertaken in live projects to improve Accessibility%.

The main purpose of the HI CAP Settings is to alleviate PDCCH scheduling congestion for DRB traffic by reducing
SRB traffic for live events and in-venue sites.
For EnodeBs under high load conditions without Hi Cap settings ACTIVATED, the SRB traffic is using majority of
the scheduling opportunities thereby leaving very little opportunities for the DRB traffic. As a result, the EnodeBs
are limited on CCEs resulting in low throughput.
HI CAP Setting recommendation update for L14A addressing accessibility concern with
SystemConstants=1::numInitialAccessAndIncomingHo(hicap)(SC556)
The following KPIs need to be closely monitored by the RF optimization engineers, once the required changes for
HI CAP Settings are implemented:
 RACH Success Rate.
 Accessibility and Retainability.
 Max and Average RRC Connected UEs.
 High/Over load.
 Handover performance.
 UL/DL Throughput.
 CCE utilization.

1. RadioBearerTable=default,DataRadioBearer=1::ulMaxRetxThreshold(hicap) and
RadioBearerTable=default,SignalingRadioBearer=1::ulMaxRetxThreshold(hicap) are each set to 8. The parameter
setting reduces the number of uplink RLC retransmissions for signaling radio bearer and data radio bearer. It will reduce SE/TTI
usage for retransmissions, and allow more SE/TTI to serve traffic. The change might cause Retainability to be same or slightly
worse.
2. RadioBearerTable=default,DataRadioBearer=1::tPollRetransmitDl(hicap) and
RadioBearerTable=default,SignalingRadioBearer=1::tPollRetransmitDl(hicap) are each set to 160 ms. It extends the
downlink time for new poll if no status report is received for both signaling radio bearer and data radio bearer. The changes will
reduce SE/TTI usage for retransmissions, and allow more SE/TTI to serve traffic.
3. RadioBearerTable=default,DataRadioBearer=1::tPollRetransmitUl(hicap) and
RadioBearerTable=default,SignalingRadioBearer=1::tPollRetransmitUl(hicap) are each set to 160ms. It extends the
uplink time for new poll if no status report is received for both Signaling Radio Bearer and Data Radio Bearer. The changes will
reduce SE/TTI usage for retransmissions, and allow more SE/TTI to serve traffic.
4. SystemConstants=1::deltaPsdRs2Tx(hicap) RS power boost is reduced from a non_hicap value of 3 (3dB) to a value of 0
(0dB) to reduce inter-site/cell interference under low Inter Site Distance (ISD) RF radio environment.
5. SystemConstants=1::numInitialAccessAndIncomingHo(hicap) is changed from a Global 10 to Local 10 or 20, and that
resultants initial accesses/incoming handovers 25/s or 50/s. It reduces the maximum number of initial accesses and incoming
handovers that are allowed during a time window without triggering the load control mechanism. The reduction is designed to
ease the pressure on PDCCH resources by reducing bursts of incoming users. Low value can result increasing numbers of RRC high
load rejections under high load. There is tradeoff between Accessibility and data throughput under the high load by using values of
10 or 20. If the data throughput are at acceptable levels, 20 can be used.
6. SystemConstants=1,systConstants::pdcchLaGinrMargin(hicap) is set to 30 (3dB). This reduces PDCCH link adaption
algorithm from 10db to 3 db. 10dB is a very conservative value meaning that many users in medium radio conditions may use 8
CCEs when they could have used 4; this aggravates the PDCCH congestion. 3dB is a reasonable compromise between saving CCE
resources and ensuring reception of PDCCH by the UE.

CASE 1 : HIGH LOAD
HOSR is
bad. Need to
delete some
NBR
relations.
Accessibility is
bad due to
high load
SOLUTION : -
 Offload the Traffic by changing Azimuth /Tilt
 Implementation of Hi-Cap Parameter
 If still traffic load is more, new site integration and deployment plan is submitted

Traffic was pretty high in alpha sector and some
activity was going on 6th December which
caused degradation in Accessibility. Alpha
sector is covering downtown
CASE 2 : HIGH TRAFFIC DUE TO SOME EVENT

CCL01851>
140930-10:41:34 107.67.27.234 10.0j ERBS_NODE_MODEL_D_1_189_COMPLETE stopfile=/tmp/15124
Connecting to 107.67.27.234:56834 (CorbaSecurity=OFF, corba_class=2, java=1.6.0_37, jacoms=R79XX07, jacorb=R79X01)
Trying file=/var/opt/ericsson/amos/moshell_logfiles/v06892/logs_moshell/tempfiles/20140930-102053_14953/ior14953
Starting to retrieve active alarms
Nr of active alarms are: 1
Date & Time (Local) S Specific Problem MO (Cause/AdditionalInfo)
2014-09-30 03:12:44 M ExternalAlarm HwUnit=SAU,AlarmPort=1 (RBS INTRUSION)
>>> Total: 1 Alarms (0 Critical, 1 Major)
Accessibility is poor in CCL01851 is due to RRC failure due to
high load at 09-29-2014 16:00 hr. Overall ERAB attempts following
the trend or no increase in the attempts. No UL RSSI, VSWR and
alarms were present in the site. No other KPIs are impacted the
site
CASE 3 : PCI CONFLICT
PCI conflict impacting accessibility

System constant
is set to default.
Earlier it was set
to 10 caused
degradation in
accessibility
CASE 4 : WRONG SYSTEM CONSTANT SETTING(SC-556)
SOLUTION : -
 Need to set proper SC-556 value.

CASE 5 : RRC DEGRADATION DUE TO RRC REJECT
If Parameters are defined as follows: noOfPucchCqiUsers – 640; noOfPucchSrUsers – 500 and RRC Conn max user
>160, then RRC can be rejected due to CQI Resource Congestion.
CASE 6 : SSSR DEGRADE DUE TO LOW S1 SIGNALING SUCCESS RATE
Sometimes it has been observed that S1 Signaling Success Rate gets degraded due to Software up-gradation.
SOLUTION : - The DUL is given reset remotely. After DUL Restart, it is observed that the cell KPIs have improved.
CASE 7 : SSSR DEGRADED DUE TO H/W ISSUE
SOLUTION : - Replacement of faulty RRUs / Auxiliary Unit / Hardware units improves SSSR.
CASE 8 :
Accessibility can also be improved by tuning the parameters – dlMaxRetxTh & ULMaxRetxTh of SRB-1 (1,2,4,8,16,32)
CASE 9 :
If there would be coverage issue then these counters can be fetched pmRadioTbsPwrRestricted, pmRadioUeRepCqiDistr,
pmbadcovevalreport.
CASE 10 :
For high UL high RSSI, these two parameters pZeroNominalPucch and pZeroNominalPusch can be increased to mitigate the
impact of high RSSI on the sector. Suggested parameter settings are as follows : -
pZeroNominalPucch: From -120 to -117
pZeroNominalPusch: From -106 to -102.

CASE 11 : S1 FAILURE / MME ISSUE
Probably the MME is not getting the message from eNB and that’s due to S1 link loosing the message before it
gets to MME.
SOLUTION : Need S1 link investigation and confirmation from MME team.

– CCL00703 Gamma sector has a high number of ERAB failures. RRC rate and S1 success rate is good.
Attached is the detailed report whereby it has been noted that all access failures in the Gamma sector are contributed
by one UE with the IMSI 310410426878445.
To find out particular UE issue, we need to analyze CTR & EBM (MME). Location of the respective traces are as follows:
CTR : /var/opt/ericsson/nms_umts_pms_seg/segment1/CELLTRACE
MME Traces:/var/opt/ericsson/sgw/outputfiles/sgeh/sgsn-mme
CASE 12 : ACCESSIBILITY ISSUES IN ERAB PHASE

qRxLevMin Change:-
If a cell having still overloaded after implementation Hi-Cap / Tilt tuning / shared traffic with neighbours, in that
case CFR, CDR and target cell HOSR effecting and move over threshold level.
So changed the qRxlevmin as per requirement ( Sprint default value is -120dBm).
Site KCXC185 Alpha and Beta facing toward a shopping Mall and Play ground, after implementation Qrxlevmin
(from -120 to -114) it’s look good, under control.
CASE 13 : FOR qRxLevMin

RETAINABILITY is defined as the ability of a user to retain the E-RAB once connected, for the desired duration.
The E-RAB Retainability QCI drops per second and percentage KPIs represent the number of abnormal active releases
initiated by the EnodeB and the MME.

1. MME INITIATED E-RAB RELEASE
2. RBS / ENB INITIATED E-RAB RELEASE

1. MME INITIATED UE CONTEXT RELEASE
2. RBS INITIATED UE CONTEXT RELEASE

1. Poor coverage*
2. Alarms*
3. High Load (high traffic)*
4. H/W issue (Re-set first) if required replace RRU*
5. VSWR over threshold*
6. HO failure : If a sector is having high HO Execution fail, it results in poor retainability.
The counter pmErabRelAbnormalEnbActHo is checked. If this counter is pegging high, it implies poor retainability
and resolution of sector HOSR is required.
*Already Mentioned in Accessibility

Counters related to ENODEB INITIATED E-RAB RELEASE:-
1. pmErabRelNormalEnb
2. pmErabRelAbnormalEnbAct
Counters related to MME INITIATED E-RAB RELEASE:-
1. pmErabRelMme
2. pmErabRelMmeAct
NOTE: MME drops are also very high during Poor RET. Need to investigate at MME end.
There is a limitation in MME drops analysis, these cannot be analyzed with the help of ENIQ alone, we need
MME statistics for this.
If MME drop is high, we need to investigate through the following steps :
 If BH/Core issue  All sectors will be impacted
 If MME issue  Multiple sites in the NW will be impacted
 Bad HW (RRU, Combiner, Antenna, cabling…)
 Incorrect cabling

1. pmErabRelAbnormalEnbActCdt – The total number of abnormal ERAB releases by the eNB per cell due cell down time (manual
intervention) with the pre-condition that the Initial Context Establishment procedure must first have been successfully completed and that
there was data in either the UL or DL buffer (i.e. active).
Probable Solutions : - Check Outage report or Fluctuation Report.
2. pmErabRelAbnormalEnbActHo – The total number of abnormal ERAB releases per cell by the eNB due to handover execution failure
and that there was data in either the UL or DL buffer (i.e. active).
 Check PCI Planning is correct or not, to avoid PCI collision issue. There should not be any PCI re-use in nearby cells (Tier 1, Tier 2 neighbours).
 Coverage issue(make Any PCI Dominant which should be based on Clutter as per Common sense). Make EDT, Change Azimuth
 High UL Interference issue on Target cell (PmRadiorecInterferencePwr). Check Connection b/w Antenna Connector & RRU Connector.
 Also Repeater is responsible sometimes for Hi-UL Interference. Might be due to Power Leakage.
3. pmErabRelAbnormalEnbActUeLost – The total number of abnormal ERAB releases by the eNB per cell due that the contact with
the UE is lost with the pre-condition that the Initial Context Establishment procedure must first have been successfully completed and that
there was data in either the UL or DL buffer (i.e. active).
 Solve the Poor Coverage issue by changing tilt / azimuth or appropriate parameter value setting, E.g. : - partOfSectorPower, ENB Power, P0NominalPucch
/ P0NominalPusch (for uplink Coverage).
 High UL NI Issue(As per earlier mentioned. Also make sure Nominal power Should not set very high otherwise it will create interference in neighbour cell).
4. pmErabRelAbnormalEnbLic – The total number of abnormal E-RAB Releases initiated by the RBS due to license reject (per cell).
5. pmErabRelAbnormalEnbActTnFail – The total number of abnormal ERAB releases per cell due to S1 interface down, "X2 interface
down" or "Transport Resource Unavailable", with the pre-condition that the Initial Context Establishment procedure must first have been
successfully completed and that there was data in either the UL or DL buffer (i.e. active).
Probable Solutions : - Issue can be resolved with the help of NOC / IM Team by raising the required tickets.
4. pmErabRelAbnormalEnbActHpr – The total number of abnormal ERAB releases by the eNB per cell due to handover preparation
and that there was data in either the UL or DL buffer (i.e. active).
 MME missing issue or MME might be disabled.
 Transport issue suspected.
 License issue suspected.
 Site Configuration issue.
SARR – Session abnormal release rate

CASE 1. DL/UL MAXRETXTHDRB TRIAL
 Current Scenarios : Change DRB dl / ul MaxRetxThreshold value
 Current Parameter Value : 8
 Current Performance Trend : Poor CFR & CDR due to Congestion and Poor MAC HARQ Succ Rate.
Any parameter or counter value can be changed : -
 dl maxRetxthdrb from 8 to 32
 ul maxRetxthdrb from 8 to 32
Description & Significance of Parameter Changes : -
These parameters are useful for improving CDR where UE is facing poor RF condition and Call drops are
due to hitting maxRetxthdrb value before t310 timer expire.
Useful for mid-cap site, where traffic is not too high. Once, we increase the value, it will also increase the drb
utilization. So, we need to be cautious while increasing the value.
0.00%
1.00%
2.00%
3.00%
4.00%
5.00%
6.00%
7.00%
8.00%
9.00%
10.00%
Connection
Failure Rate
Connection Drop
Rate
Pre avg Stats(21-May
to 03-June)
Post avg Stats(05-
June to 18-June)
0
100000
200000
300000
400000
500000
Pre avg Stats(21-
May to 03-June)
Post avg
Stats(05-June to
18-June)
RRC Atts
RRC Atts

Site is located near
to San Jose airport
and it had high UL
RSSI which caused
Retainability
degradation
CASE 2 : HIGH UL RSSI WHICH CAUSED RETAINABILITY DEGRADATION

tinactivity timer value is changed from 61s to 20s in region-6 , After changes a very good improvement was observed in
ERAB drop rate (Approx. 2% marginal improvement).
CASE 3 : tinactivity TIMER_ERAB DROP RATE IMPROVEMENT
Final Result-
1. Number of RRC Attempts increased, as timer decreased accordingly UE could attempt again while RRC_EST_SR is
following the same trend range .
2. E-RAB Retainability % much improved .

CASE 4 : RETAINABILITY DROP DUE TO TRAFFIC DIP
Weekend traffic is less due to site is in business area and Retainability increased significantly for alpha sector after
changing down tilt

ISSUE: Nearby site may be On-Air which is having partofsectorpower = 100%, which caused degradation in HOSR.
CASE 5 : PART OF SECTOR POWER

HOSR bad for below mentioned NBR relations. Need to delete CVL00512_9A->CVL02262_9C and increase
cellindividualoffset for CVL00512_9A->CVL02534_9C from 0 to 3, and need to increase cellindividualoffset to 5 from
3 for intra sectors.
CASE 6 : RETAINABILITY ISSUE DUE TO HO FAILURE

Some distant NBR
relations were
blocked and cell
range was modified
to improve
retainability
CASE 7 : HO FAIL CAUSE RETAINABILITY ISSUE

 From drive test analysis, it was observed that a large portion of the drop calls were due to poor radio environment.
 Just before HO, it was observed that the UE SINR was poor and this caused the UE to drag the call in poor radio environment
rather than HO faster to a neighbour cell with better RSRP.
 In this optimization project, 2 parameters are recommended to be tuned; a3offset and a2TresholdRsrpPrim.
 a3offset : Change from 3 to 2 dB
 a2TresholdRsrpPrim : Change from -120 to -110 dBm.
 A trial was also conducted to evaluate the impact of changing the values below for a few sites with high DCR:
 DataRadioBearer : dlMaxRetxThreshold / ulMaxRetxThreshold – Change from 8 to 32
 SignalingRadioBearer : dlMaxRetxThreshold / ulMaxRetxThreshold – Change from 8 to 32
 With current A3 setting, A3 event handover will be performed when neighbor cell is greater than a3Offset + hysteresis (RSRP)
of the current serving cell.
 a3Offset = 3 dB, hysteresis = 1dB  Handover will only be performed once Neighbor Cell RSRP > 4dB of Serving Cell RSRP
 Thus, it is important to expedite the HO with reduction of a3Offset to 2 dB.
 After the parameter change, it was observed that the drop calls due to call dragging was reduced in a cluster of 20 sites.
 RL Failure Timing
 t-PollRetransmit = 45ms (SRB), 50ms (DRB)
 If retransmission limit increases from 8 to 32, RL failure due to retransmission limit reached:
 SRB: 360ms (8) to 1440ms (32)
 DRB: 400ms (8) to 1600ms (32)
< T310 (2000ms)
Therefore, from drive test analysis, it is often
observed that the drop occur before T310
time out because ReTx hits upper limit first
CASE 8 : RADIO LINK ISSUES

CASE 9 : CASE STUDY OF LR13XC102 MME DROP
Below are the steps to isolate if issue is related to site:
 Verify sites configuration (tilt, parameters…)
 Verify alarms on the site
 Check UL noise for the site
 Check LTE traffic (# of UEs) on site from Cockpit/ENIQ
 Verify traffic (# of UEs) make sense based on site location (Google)
 Compare LTE traffic with neighbor site in the same area
 Compare LTE traffic for site with CDMA/EVDO traffic
Alpha & Beta sector has high CDR Beta sector has high MME drops
 Beta sector has high MME drop whereas Alpha/Gamma are not bad
 RCA from team was BH/Core issue
 If BH/Core issue  All sectors will be impacted
 If MME issue  Multiple sites in the NW will be impacted
 Site with BH/Core issue  gnoc.ericsson.core.tier1@ericsson.com
 If site get routed to core team then issue will not be resolved as RCA was not accurate
CONTD.

 Verify sites configuration (tilt, parameters…)
 LR13XC102 has correct parameter configuration
 Changed the tilts  traffic not improved
 3G is still on MC (Legacy)
 Verify alarms on the site
 Intermittent VSWR alarm for Gamma
 Intermittent STCP alarm  last alarm was more than 2 weeks ago
 Check UL noise for the site
 UL noise on all sectors was less than -116 dBm
LR13XC102 LTE TRAFFIC LR13XC102 LTE TRAFFIC VERIFICATION - GOOGLE
Traffic on Alpha/Beta is very low  Coverage or Location ??
Based on neighbor sector providing coverage in the area there is good LTE traffic but LR13XC102 Alpha still has very low LTE traffic
Based on neighbor sector providing coverage in the area; LR13XC102 Alpha sector has comparable EVDO traffic (Legacy) compare to
neighbor site
Based on Voice/EVDO traffic this site carry high traffic so having very low traffic for LTE indicate there is issue on this site.
CONTD.

LR13XC102 ANALYSIS
 Based on the performance analysis done on the site; results are pointing for site to have a weak coverage; probable cause:
 Bad HW (RRU, Combiner, Antenna, cabling…)
 Incorrect cabling
 As all 3 sectors are having low traffic issue so it is less likely to have bad HW on all the sectors; high probability is incorrect
cabling (most likely due to Comscope combiner)
 Will need to check what type combiner is installed on the site
 If cabling was wrong that may have damaged the combiner/RRU and we will need to replace HW
LR13XC102 COMBINER
 There are 2 types of combiner used and based on the combiner type cabling is different; check type of combiner installed on
site using Antenna Asset form on Site handler
 Comscope combiner serial # starts with “C”
 RFS combiner serial # starts with “RFS”
Comscope Combiner RFS Combiner
CONTD.

TROUBLESHOOTING WITH CX TEAM
 CX team went to site and found incorrect combiner cabling
 Fixing the cabling  didn’t solve issue on this site
 Replacing the combiner  didn’t solve issue on this site
 Majority of time fixing the cabling and/or replacing the combiner will solve the issue but for this site didn’t, can be:
 Incorrect new combiner
 Cabling was not corrected
 Requested CX team to bypass the combiner to see if traffic improve  Alpha sector # of UEs increased from 2 to 50 !!
 Bypassing combiner confirmed there was coverage issue
 Bypassing combiner confirmed the issue is on the tower not ground
 Bypassing combiner confirmed the issue is not due to BH/Core
LR13XC102 CFR/CDR - POST
Alpha Beta Gamma
After bypassing combiner; CFR & CDR improved for the site
# of MME drops increased on Gamma; but overall impact on CDR is low  Should be able to improve with fine tuning
CONTD.

COMBINER CABLING ISSUE
 RFS combiner has 4 ports on one end that connects to RRU and 2 port on the other end connects to Antenna
 Comscope combiner has 2 port on one end that connects to RRU and 4 ports on other end (2 for RRU & 2 for Antenna)
 Most common issue is CX team connect 2 ports on one end that should be connected to RRU to the Antenna and connect
RRU to the 4 ports on the other end
COMSCOPE COMBINER CABLING

Reporting – The UE sends the Source eNodeB an Event A3 that contains monitored neighbor cells
Preparation – The Source eNodeB sends a request to the Target eNodeB, which performs admission control
Execution – After successful preparation, the Source eNodeB sends a handover command to the UE
The ability to provide the requested service to the user with mobility
Mobility Success Rate [%]:

MOBILITY X2 BASED HO PREPARATION
MOBILITY X2 BASED HO EXECUTION

X2 HANDOVER
1. RRC MEASUREMENT REPORT
Event A3: Neighbor becomes
amount offset better than serving
Leave event A3:
Mn+cellIndividualOffsetEUtran+hysteresisA3<Ms+a3Offset
Measurement of
RSRP or RSRQ
Filter out the impact of large
scale fast fading based on
filterCoefficientEUtraRsrp
filterCoefficientEUtraRsrq
Meet Event A3 criteria
Mn+cellIndividualOffsetEUtran-hysteresisA3>Ms+a3Offset
Measurement
Report

cellA with noof
Hoattempts<min
BestCellHoAttempts
exists?
Choose cellB in best
cell candidates list that
fullfills
noofHoattempts<minBe
stCellHoAttempts
Best cell: cellA
Best cell: cellB
noofHoattempts(cellA)++
noofHoattempts(cellB)++
Cell unknown
Cell knowm
No NR
X2 allowed
X2 not allowed
ANR
X2 HO
S1 HO
Measurement Report
2. HO DECISION
Source eNB makes a HO decision based on Measurement Report.
minBestCellHoAttempts: operator controlled parameter, decides how many ho attempts shall be performed on a cell
before the next best cell is chosen.
Best Cell Evaluation
X2 HANDOVER

UE
Source
eNB
Target
eNB
Source
S-GW
Target
S-GW
1. RRC Connection Reconfiguration
(Measurement Conf)
2. RRC Measurement Report
(Event A3)
3. HO Decision
4. S1 Handover Required
(Source to target Transparent Container)
8. Admission
Control
9. S1 Handover Request Acknowledge
13. RRC Connection Reconfiguration
Handover Commond
Regenerate
Security Keys 14. MAC: Random Access Preamble
15. MAC: Random Access Response (UL Allocation+TA)
16. RRC Connection Reconfiguration Complete
(Handover Confirm)
17. S1 Handover Notify
18. Data Transfer in Target
20. S1 UE Context Release
(Cause: Successful Handover)
RRC Connected
RRC Connected
Source
MME
Target
MME
5. S10 Forward Relocation Request
6. S11 Create Session Req/Res
7. S1 Handover Request
10. S10 Forward Relocation Response
11. S11 Create Bearer Req/Res
Up Forwarding
12. S1 Handover Commond
19. S10 Forward Relocation
Complete/ACK
HO Prep Att ++
HO Prep Suc ++
HO Exec Att ++
HO Exec Suc ++
S1 HANDOVER

1. RRC MEASUREMENT REPORT
Event A3: Neighbor becomes
amount offset better than serving
Leave event A3:
Mn+cellIndividualOffsetEUtran+hysteresisA3<Ms+a3Offset
Measurement of
RSRP or RSRQ
Filter out the impact of large
scale fast fading based on
filterCoefficientEUtraRsrp
filterCoefficientEUtraRsrq
Meet Event A3 criteria
Mn+cellIndividualOffsetEUtran-hysteresisA3>Ms+a3Offset
Measurement
Report
S1 HANDOVER

cellA with noof
Hoattempts<min
BestCellHoAttempts
exists?
Choose cellB in best
cell candidates list that
fullfills
noofHoattempts<minBe
stCellHoAttempts
Best cell: cellA
Best cell: cellB
noofHoattempts(cellA)++
noofHoattempts(cellB)++
Cell unknown
Cell knowm
No NR
X2 allowed
X2 not allowed
ANR
X2 HO
S1 HO
Measurement Report
2. HO DECISION
Source eNB makes a HO decision based on Measurement Report.
minBestCellHoAttempts: operator controlled parameter, decides how many ho attempts shall be performed on a cell
before the next best cell is chosen.
Best Cell Evaluation
S1 HANDOVER

Typically, handover preparations fail if there is something wrong with the target cell.
POSSIBLE CAUSES OF HANDOVER PREPARATION FAILURES
 MME pool should be same.
 If HO-Preparation fail = 100%, it might be due to MME pool different at source and target end.
 The command get . termpointmme can be used to find out the MME pool IPs. If different, set as per Market MME
pool.
 SpidHoWhiteList is active on the target, which has primaryplmnReserved set to true.
 Target cell is overloaded (High capacity): Need to offload target cell (already describe in accessibility part).
 Target cell Unavailable : The target cell is down / disabled, PLMN Status is true but partOfSectorPower is set to maximum
value. The command lgd can be used to check the site status, get . primaryplmn is used to find out the PLMN status and get .
power is used to find out the site power status.
 TAC not defined on site, as per network design : TAC on site should be defined as per network design. If HO-Prep
fail% is not uniform for any cluster or market, then the command get . tac is used to find out TAC status.
 License issue/Software issue.
 Target cell has a fault (alarm, disabled cell, etc.)
POSSIBLE CAUSES OF HANDOVER EXECUTION FAILURES
 ANR PCI Conflict (Collision & Confusion)*
 Target exceeds cell range: The target cell is more than 15km from the UE (or the current cell range setting). In that case
Ho-Exec fail occur. Need to change cell range or cellindividualoffset b/w relation (as per required)
 Target is a sleeping cell – The target cell is sleeping, need fixed sleeping on daily basis.
 Target has high uplink interference*
 Poor RF conditions*
 Due to radio deaf radio: If UL N+I is less than -119dBm, in that case Ho-Exec fail occur.

HANDOVER RELATED COUNTERS can be categorized as follows: -
 Preparation Success Rate
 pmHoPrepSuccLteIntraF / pmHoPrepAttLteIntraF
 Execution Success Rate
 pmHoExeSuccLteIntraF / pmHoExeAttLteIntra
 Handover Success Rate
 Preparation Success Rate x Execution Success Rate
NOTE : Counters are pegged on the SOURCE!!!
Primary
HO Preparation Counter HO Execution Counter
pmHoPrepAttLteIntraF pmHoExeAttLteIntraF
pmHoPrepSuccLteIntraF pmHoExesuccLteIntraF
Secondary
pmHoPrepRejInLicMob
pmHoPrepRejInBearerAdmissionRej
pmHoPrepRejInHighload
pmHoPrepRejInOverload

Following is the list of all the parameters that can be tuned to improve intra LTE HOSR / A3 Event triggering.

Some of the more commonly tuned / optimized parameters for improving intra LTE HOSR are as follows:
1. cellindividualoffsetEutran
2. hysteresisA3
3. timeToTriggerA3
The following table provides a brief description about the above three parameters for Ericsson systems (as
defined in ALEX).
PARAMETER PARAMETER DESCRIPTION RANGE AND VALUES DEFAULT VALUE UNIT
cellIndividualOffsetEUtran
Offset value for the neighbor
cell. Used when UE is in
connected mode. This
attribute can be modified by
SON functions.
-24,-22,-20,-18,-16,-14,-12,-
10,-8,-6,-5,-4,-3,-2,-
1,0,1,2,3,4,5,6,8,10,12,14,16,1
8,20,22,24
0 dB
hysteresisA3
The hysteresis value for
eventA3. 0..150 10 dB
timeToTriggerA3
The time to trigger value for
eventA3.
0,40,64,80,100,128,160,256,3
20,480,512,640,1024,1280,25
60,5120
640 ms

IFHO FUNCTIONALITY FOR EVENT A5
The IFHO functionality depends primarily on 6 parameters
1. a5Threshold1Rsrp: This determines the threshold below which the serving cell has to be.
1. a5Threshold2Rsrp: This determines the threshold above which the target cell has to be.
2. a5Threshold1RsrpAnrDelta: This is added to a5Threshold1Rsrp.
3. a5Threshold2RsrpAnrDelta: This is subtracted from a5Threshold2Rsrp.
4. a2ThresholdRsrpPrim: This determines the level after which A5 for IFHO should be triggered.
5. a1a2SearchThresholdRsrp: In case of MCPC, this parameter needs to be tuned.
6. a1ThresholdRsrpPrim: This determines if the UE has entered into good RF conditions again for the serving
cell and subsequently, event A1 is triggered. All A2 / A5 events will be cancelled.
In order to understand IFHO lets consider the scenario with the different responsible parameters set to values
as shown below for the source cell.

IFHO FUNCTIONALITY FOR EVENT A5
NOTE: If a1threshold is triggered between A2 and A5 trigger (between C and D), then it cancels the handover measurements for IFHO and
the UE will not be measuring other frequencies anymore. So, A1 threshold should be chosen more than A2 threshold, in order to avoid this.
A B
C D
A5 ANR is
trggered
A2 is
trigger
ed
A5 IFHO is
triggered
A – At this point, the source cell RSRP gets below
a5anr1 and target call RSRP gets better than a5anr2;
therefore, A5 ANR will be triggered. ANR feature
would now add neighbor relations / X2 in the time
duration between Point A and Point C.
B – At this point, the source cell RSRP gets below
A5th1 and target cell RSRP gets better than a5th2;
then, the triggering condition for event A5 is met; but
IFHO won’t happen, since A2 is not yet triggered.
C – At this point, event A2 is triggered, since the
source falls below a2thprim.
D – At this point, A5 IFHO takes place; since event A2
triggering condition is met as well as A5th2 criteria is
also satisfied.

Typically, IFHO Handover (Prep & Exec) fails due to something wrong with the target cell. Execution failure in
Inter HOSR is same as Intra HOSR execution fail.
POSSIBLE CAUSES OF HANDOVER PREPARATION FAILURES
 IFHO Feature should be enabled at target end:
 MME pool should be same.**
 SpidHoWhiteList is active on the target, which has plmnReserved set to true
 Target cell is overloaded (High capacity).*
 Target cell Unavailable.**
 TAC not defined on site, as per network design.**
 License issue/Software issue
 Target cell has a fault (alarm, disabled cell, etc)
Parameter Name Value
anrInterFreqState 1
featureStateInterFrequencyLTEHandover 1
featureStateInterFrequencySessionContinuity 1
**Already Mentioned in intra HOSR

MOC PARAMETER NAME
SPRINT
PARAMET
ER VALUE
- MACRO
SITE
DEFAULT
VALUE PARAMETER TYPE SPRINT CATEGORY
ReportConfigA5 a5Threshold1RSRP -107 -140 Sprint Golden Parameter Handover and Cell Reselection
ReportConfigA5 a5Threshold2RSRP -115 -136 Sprint Golden Parameter Handover and Cell Reselection
ReportConfigA5 hysteresisA5 10 10 Sprint Golden Parameter Handover and Cell Reselection
ReportConfigA5 timeToTriggerA5 480 640 Default Parameters Handover and Cell Reselection
MOC
PARAMETER
NAME
SPRINT
PARAMETER
VALUE - MACRO
SITE
DEFAULT
VALUE PARAMETER TYPE SPRINT CATEGORY
ReportConfigSearch
a1a2SearchThresh
oldRsrp
-103 -134
Sprint Golden
Parameter
Mobility Control At Poor
Coverage
ReportConfigSearch
hysteresisA1A2Se
archRsrp
20 20
Sprint Golden
Parameter
Mobility Control At Poor
Coverage
If MCPC enabled, then the following parameters are used : -

 AT&T supports MCPC (Mobility Control at Poor Coverage)feature which is used to reduce IRAT HO triggering
rate , keeping retainability intact.
 FGA (Field Guide Alert)56 used for single carrier site and FGA 50 is used for multi carrier site.
 MobCtrlAtPoorCov::featureStateStateMobCtrlAtPoorCov [ENodeB, 1, boolean, Global] provides
information about the licensed feature – Mobility Control At Poor Coverage. The feature needs to be set to 1
to activate it for single and multi carrier sites.

 MobCtrlAtPoorCov::serviceStateStateMobCtrlAtPoorCov [EnodeB, 1, boolean, Global] Indicates the licensed feature
Mobility Control At Poor Coverage. The feature needs to be set to 1 (activated) for single and multi carrier sites. This
is non operator configurable parameter.
 EUtranCellFDD::mobCtrlAtPoorCovActive [Cell, TRUE, TRUE/FALSE, Global] Specifies if the feature Mobility Control
at Poor Coverage is enabled or disabled in the cell. The parameter needs to be set to TRUE for single and multi
carrier sites.
 ReportConfigSearch::a1a2SearchThresholdRsrp [Cell, See Table, dBm , Global] The Reference Signal Received Power
(RSRP) threshold value for events A1Search and A2Search. For single-carrier sites, a1a2SearchThresholdRsrp replaces
a2ThresholdRsrpPrim parameter. It needs to be set to -116 for intraLTE, -112 for interRAT_10 and -110 interRAT_5.
Please refer to FGA50 for the value on interLTE, mixedBW and multiCarrier sites.
 ReportConfigSearch::a2CriticalThresholdRsrp [Cell, See Table, dBm , Global] The Reference Signal Received Power
(RSRP) threshold value for event A2Critical. The a2CriticalThresholdRsrp parameter replaces a2ThresholdRsrpSec (it
was applied in single-carrier sites). The setting for a2CriticalThresholdRsrp is -122 for single and multi carrier sites.
 ReportConfigSearch::timeToTriggerA2Critical [Cell, 1280, ms, Global] The time-to-trigger value for measurement in
event A2Critical. This parameter is set to 1280ms for single and multi carrier sites.
 ReportConfigB2Utra::timeToTriggerB2 [Cell, 1280, ms, Global] The time to trigger value for the eventB2
measurement. This parameter is set to 1280ms for all sites.

Major reasons / causes behind poor IRAT handover success rate are as follows : -
 Coverage gap between LTE & 3G/Other Technology.
 Improper parameter setting (a1a2SearchThresholdRsrp, a2CriticalThresholdRSRP, b2ThresholdRscpUtra).
The Best way to optimize IRAT is doing physical optimization. We can use tilt meter to adjust the EDT.
Antenna tilt can be checked through the command: get . electrical
Antenna model no. can be checked through the command get . antenna

We can check following two counters to perform IRAT analysis
 pmBadCovSearchEvalReport
 pmCriticalBorderEvalReport
PROCESS TO FETCH THE COUNTERS
STEP 1: Open ITK, Go to Stats and then open PM Dyna View.
STEP 2: Go to Additional Counter Select Node Type ENB and MO Class EUtranCellFDD and select the counter
button as shown below:
STEP 3: Select the above mentioned counter.

If more samples are found under pmBadCovSearchEvalReport, we can change the values of the parameters –
a1a2SearchThresholdRsrp, b2Threshold2RscpUtra.
We found that in WCL01558, the gamma sector has high IRAT and also found very high samples under
pmBadCovSearchEvalReport.
We, then, changed a1a2SearchThresholdRsrp from -110 dBm to -112 dBm and b2Threshold2RscpUtra from -115
dBm to -105 dBm on 20/04 and found good improvement in IRAT as shown below.

If more samples are found under pmCriticalBorderEvalReport, we can change the value of the parameter –
a2CriticalThresholdRsrp.
We found SCL00197 Gamma sector has high IRAT and also found very high samples under pmCriticalBorderEvalReport.
We, then, changed the value of a2CriticalThresholdRsrp from -122 dBm to -124dBm on 04/29 and found good
improvement in IRAT.

CASE 1 : INTRA LTE HOSR (PREPARATION)
Date EUtranCellFDD EUtranCellRelation pmHoPrepSuccLteIntraF pmHoPrepAttLteIntraF
Prep Fail
Count
5/3/2014 FVHGILDCBBULTE035474124 310120-354229-26 0 1659 1659
5/3/2014 FVHGILDCBBULTE035474124 310120-354229-27 0 95250 95250
Missouri LTE 800 HO-Prep Fail = 100% with a target cell; as the target cell is still not launched, but FDD is unlocked/
enabled and primary PLMN status is TRUE (for a launch site primary PLMN should be False).
Probable solution: -
 Target cell FDD should be Locked if the site is not launched.
 If the site is launched, in that case Primary PLMN status should be changed to False.
Target cells, 26-Bata, Target cells,
26-Bata, 27-Alpha given 100% fail
with source
Target Cells FDD status should be
Locked is site is not officially
launch

EUtranCellRelation % HO Fail Rate -HO Prep Fail EUTRAN Cell Fdd Id Cascade
310120-434234-2 99.70% 56632 PTRCFLAHBBULTE043423421 TA03XC060
CASE 2 : HO_PREP FAILURE DUE TO SECTOR DOWN
CellId #UE:s #Bearers
1 0 0
2 0 0
3 11 11
Note: Here we can see that 2nd sector not taking call as sector is down. Hence HO_Prep failure happening.
EUtranCellRelation % HO Fail Rate -HO Prep Fail Tampa Cascade
310120-434293-3 93.04% 162382 SPBGFLTEBBULTE043429331 TA03XC123
SPBGFLTEBBULTE0434293> Nr of active alarms are: 2
====================================================================================================================
Date & Time (Local) S Specific Problem MO (Cause/AdditionalInfo)
====================================================================================================================
2013-11-21 19:35:20 M Disconnected ExternalNode=2 (hubPosition: A6)
2013-11-22 15:17:20 M Upgrade Package Corrupt UpgradePackage=CXP102051%18_R23BM (file_error)
>>> Total: 2 Alarms (0 Critical, 2 Major
OBSERVATION: In newly integrated sites, huge HO_Prep fail% have been observed. The main cause is
found to be : - Software package installed is getting corrupted.
CASE 3 : HO_PREP FAILURE DUE TO SOFTWARE PACKAGE CORRUPTED

1
CASE 4: ANR PCI CONFLICT
Site A
January
6
Site B
February
5
Site C
March
› Site A online in January
› Site B online in February
– Site A   Site B neighbors
› Site C online in March
– UE reports PCI, eNB executes HO to Site B
instead of Site C
UE only
reports PCI,
not CGI

DXL23002
DXL00221
DXL03002
DXL03040
DXL20221
DXL23040
DXL20567
DXL00567
DXL03162
DXL23162
Date EUtranCellFDD EUtranCellRelation pmHoPrepSuccLteIntraF pmHoPrepAttLteIntraF HOPrepFails
5/27/2011 DXL23040_2C DXL23040_2B 3 367 364
Date EUtranCellFDD EUtranCellRelation pmHoPrepSuccLteIntraF pmHoPrepAttLteIntraF HOPrepFails
5/27/2011 DXL23002_2A DXL23040_2B 5 168 163
Date UTC Hour EUtranCellFDD EUtranCellRelation pmHoPrepSuccLteIntraF pmHoPrepAttLteIntraF HOPrepFailures
5/27/2011 19:00 DXL23040_2C DXL23040_2B 1 365 364
HO Prep failures occurred in DXL23040 as IntraLTEHandover feature had
been disabled.
CASE 5 : HO PREPARATION FAILURE DUE TO INTRA LTE HANDOVER FEATURE DISABLED

PROCESS FLOW
Read site list
(Internal dB)
Read sites on Air
(ENIQ, based on Attempts > 0)
Read Cell Relations
(ENIQ, Success < 90%)
Compute PCI Distances
(Finder Algorithm)
Determine Closer Cell
(Finder Algorithm)
Reporting – CSV File
(Finder Algorithm)
Source Target
Dist.
(km) PCI
Closer Cell
w/PCI
Closer
Dist. (km)
Exec Succ
Rate (%)
Exec
Fail
385325-3 385358-1 35.7 66 385038-1 2.6 0 47811
385382-2 385358-1 39.7 66 385038-1 5.2 0 11851
385325-2 385358-2 35.7 235 385038-2 2.6 0 4827
385382-2 385358-3 39.7 404 385038-3 5.2 0 2617
336286-1 336395-3 40.0 405 336458-3 2.4 0 2450
385239-3 385395-3 77.5 366 385458-3 5.3 0 1877
303399-3 303276-2 95.5 191 303106-2 7.7 0 1787
336286-1 336395-2 40.0 236 336458-2 2.4 0 1450
336286-1 336395-1 40.0 67 336458-1 2.4 0 1292
303159-2 303426-2 31.9 296 303265-2 4.0 0 1214
385110-3 434421-3 47.5 355 385102-3 5.3 0 1200
385303-2 336167-1 205.9 152 385363-1 14.0 0 1189
336452-2 335995-2 8.8 259 335921-2 8.4 0 915

EUtranCellRelation % HO Fail Rate -HO Exec Fail SWF Cascade
310120-426013-1 100.00% 21490 FTMYFLGRBBULTE042601311 MI13XC030
CASE 6 : HO_EXECUTION FAILURE DUE TO RADIO DEAF
NOTE: Cell having very low N/I(-121)dBm. Probably Radio is deaf and Call is not able to be established on
the target cell.

Memphis IFHO% Status
Date Intra HOSR Inter HOSR
7/17/2014 98.50% 93.40%
7/18/2014 98.90% 92.00%
7/19/2014 98.90% 92.70%
7/20/2014 98.80% 93.40%
7/21/2014 98.80% 92.80%
7/22/2014 98.70% 92.90%
7/23/2014 98.70% 93.70%
7/24/2014 98.80% 99.80%
PRE-POST TABLE
PRE-POST FLOW CHART

EUtranCellFDD EUtranCellRelation
Target
Cascade ID ON-AIR Date Date
pmHoPrepAt
tLteInterF
pmHoPrepSu
ccLteInterF
Inter
Fail
MMPNTN14BBULTE032785121 310120-329997-2 329997 MP54XC251 6/4/2014 7/22/2014 68522 0 68522
MMPKTNLPBBULTE032772121 310120-329997-26 329997 MP54XC251 6/4/2014 7/22/2014 37626 0 37626
CRVLTN13BBULTE032780621 310120-330040-2 330040 MP03XC161 6/4/2014 7/22/2014 34800 0 34800
GTWSTNAQBBULTE032780331 310120-330042-3 330042 MP03XC141 6/4/2014 7/22/2014 17816 0 17816
MMPOTN89BBULTE032787311 310120-329997-26 329997 MP54XC251 6/4/2014 7/22/2014 9933 0 9933
MMPKTNLPBBULTE032772131 310120-329997-26 329997 MP54XC251 6/4/2014 7/22/2014 3746 0 3746
OLBRMS50BBULTE032788031 310120-330042-27 330042 MP03XC141 6/4/2014 7/22/2014 3743 0 3743
MMPNTN14BBULTE032785121 310120-329997-25 329997 MP54XC251 6/4/2014 7/22/2014 3547 0 3547
MMPOTN89BBULTE032787331 310120-329997-26 329997 MP54XC251 6/4/2014 7/22/2014 3431 0 3431
IMPACTED CELLS OF MARKET
PARAMETERS RECOMMENDED:
Parameter Name MO Class Name
Need to
impleme
nt
Curre
nt
Value
anrInterFreqState AnrFunction=1,AnrFunctionEUtran=1 1 0
featureStateInterFrequencyLTEHandover Licensing=1,OptionalFeatures=1,InterFrequencyLTEHandover=1 1 0
featureStateInterFrequencySessionContinuity Licensing=1,OptionalFeatures=1,InterFrequencySessionContinuity=1 1 0
CONCLUSION:
1. All required parameters must be enable for IFHO( FDD to FDD) at target end.
2. Except these parameters one more parameters should be enable for FDD to TDD handover
1. IntraLteintermode

FORMULA FOR DL/UL THROUGHPUT
 Analysis flow for low throughput investigation from performance counters point of view
 Contributing factors to end user throughput
 Key learning
 Analysis flow for DL throughput
 Analysis flow for UL throughput
 Parameter settings at ENodeB
 Essential features at ENodeB
 KPI/Counters to check for throughput analysis
 Key Learning

THROUGHPUT OPTIMIZATION
LTE END USER QUALITY OF SERVICE IS IMPACTED BY THE CUMULATIVE EFFECT OF VARIOUS NODES & INTERFACES.
THE PICTURE BELOW SHOWS THE CONTRIBUTING FACTORS TO END USER THROUGHPUT.
Mobility
• HO
Ping pong
• Packet
forwarding
End user throughput
BLER at Air I/F:
Retransmission
rate
Radio Environment
• C/I, SINR
• Link Adaptation
• MCS allocated
Delay of cell
transition
Available
bandwidth
per user
E2E Dimensioning
• Nbr of active
users/cell
• RB allocated
• Backhaul
End to End
Performance,
Core ntwrk delays
Core network /
PDN performance
• IP delays
• Router / #of hops
• Packet losses
• Session
Performance
Session
Establishment
Times
ENodeB setup
Params
Audit
• Rec. values
ENodeB
features
• MIMO 2x2 4x4
• HARQ
Peak
performance
End server /
UE laptop
• TCP/IP
settings
• MTU size
TCP/IP issues

THROUGHPUT CHECK : USEFUL COUNTERS

ANALYSIS FLOW FOR DL THROUGHPUT INVESTIGATION
Total Performance
Check all important Accessibly, Mobility and Retainability KPI. Holistic overview of
performance makes analysis simpler
RRC Connected Users
Dl Throughput would reduce with increase in number of connected users
(pmRrcConnMax).
CQI ,64/16QAM,TM
Modes
Av CQI, % 64QAM samples and RI indicates DL SINR status. Average CQI should be high
(>10%), % of 64QAM sample should be high (>10%),
PRB(DL) And PDCCH
Utilization
High PRB and PDCCH utilization would impact the DL Throughput. (pmPrbUtilDl /
pmPrbUtilUl).
Power Limited UE
And No Of A2 Events
High occurrence of pmRadioTbsPwrRestricted and pmBadCovEvalReport indicates poor
DL coverage.
DL Latency And RLC
Retransmission
High value of DL latency(>9ms) and RLC retransmission(> 1%) would impact DL
throughput.
BASIC HEALTH CHECK UP AND BASELINE PARAMETER/FEATURE AUDIT ALONG WITH ALL CHECKS

Total performance
Check all important Accessibly, Mobility and Retainability KPI. Holistic overview of performance
makes analysis simpler
Alarm & Parameter/
Feature Check
Make Baseline Audit for Parameter and feature.
RSSI
High uplink RSSI would impact the throughput (pmRadioRecInterferencePwrPUCCH /
pmRadioRecInterferencePwr)
% of 16 QAM samples Low usage of 16 QAM modulations scheme in UL would impact the UL throughput
PUCCH & PUSCH SINR Poor UL SINR conditions would impact UL throughput. (pmsinrpucchdistr & pmsinrpuschdistr)
Power limited UE
High number of power limited UE indicates poor uplink coverage. (pmRadioTbsPwrRestricted
,pmRadioTbsPwrUNRestricted)
ANALYSIS FLOW FOR DL THROUGHPUT INVESTIGATION

DOWNLINK THROUGHPUT TROUBLESHOOTING
The general troubleshooting strategy is described in the following flow diagram along with different factors
responsible for poor throughput.
Figure 1. Low Throughput causes in the Downlink for LTE networks
At the end of this methodology, you will be able to determine if the reasons for low throughput in your cells is
one of the following or a combination of these factors : -
 BLER (bad coverage)
 Downlink Interference (Bad CQI)
 MIMO Parameters
 Scheduling algorithm
 Low Demand
 CQI reporting frequency
 Other (VSWR, Backhaul capacity)

At the end of this methodology, you will be able to determine if the reasons for low throughput in your cells is
one of the following or a combination of these factors : -
 BLER (bad coverage)
 Downlink Interference (Bad CQI)
 MIMO Parameters
 Scheduling algorithm
 Low Demand
 CQI reporting frequency
 Other (VSWR, Backhaul capacity)
DOWNLINK THROUGHPUT TROUBLESHOOTING
The general troubleshooting strategy is described in the following flow diagram along with different factors
responsible for poor throughput.
Figure 1. Low Throughput causes in the Uplink for LTE networks

THROUGHPUT TESTING : CHECKS
The following licenses are applied/enabled/operable. Parameters are set to default
 Downlink/Uplink Baseband Capacity
 Channel Bandwidth
 64-QAM DL / 16-QAM UL
 Dual Antenna DL Performance Package
IMPACT OF PRB UTILIZATION ON THROUGHPUT IN LTE
 Objective is to show impact of high PRB utilization in UL and DL on throughput
 Number of PRB utilization depends on the bandwidth of LTE system
 For a 10 MHz system Number of PRB would be 50
 Along with connected user it is one the resource which limits the performance of LTE system particularly
throughput

 Counters pmPrbUtilUl and pmPrbUtilDl are the PDF counters with 10 ranges each
 Concept of weighted average is used to calculate average PRB utilization. Weight of each range (for PDF
range[0] from 0 to 10 it has taken as 5) is multiplied by sample in that range and sum of it is divided by total
number of samples(in one ROP of 15 minutes it is always going to be 15)
CALCULATION OF PRB UTILIZATION
WAYS TO REDUCE PRB UTILIZATION
 There are very limited means of reducing of PRB utilization .How ever some of these methods can be tried on
case by case basis
 Traffic offload to less utilized neighboring cells
 Reduce control channel resources(Before that check PDCCH utilization)
 Add Bandwidth (if system is operating < 20Mhz) as Bandwidth increase would increase number of PRB
 Reduce inactivity timer (tInactivityTimer) value so that inactive user can be released early

ESSENTIAL FEATURES
 IRC (interference rejection combining) should be enabled.
 Ul FSS (Ul frequency selective scheduling) should be enabled.
 Channel Bandwidth (5, 10, 15 and 20) MHz should be equal to licensed bandwidth.
 64-QAM DL should be enabled.
 16-QAM UL should be enabled.
 Dual Antenna DL Performance Package or MIMO should be enabled.
ALL THESE FEATURES SHOULD BE ENABLED AT ENODEB FOR GOOD UL AND DL THROUGHPUT
ESSENTIAL PARAMETERS
Radio Network MO parameters:
 EUtranCellFDD
 dlChannelBandwidth / ulChannelBandwidth=should be equal to license bandwidth
 noOfTxAntennas for MIMO= 2
 noOfRxAntennas for MIMO= 2
 transmission Mode default is 3, TxDiv and Open Loop Spatial Multiplexing (2x2 MIMO)
 pdcchCfiMode (number of OFDM symbols used for PDCCH, 1->3)
 maximumTransmissionPower = 460 (for 40 watt site)
 partOfSectorPower (for a sector)= 100
 pZeroNominalPucch  some UEs need this to be increased or ACK/NACKs are not received successfully on PUCCH.
 pZeroNominalPusch  some UEs need this to be increased from default or lots of errors seen on PUSCH.
 SectorEquipmentFunction
 confOutputPower = license power (20/40/60 Watt)

 UL Interference on PUCCH / PUSCH : pmRadioRecInterferencePwrPUCCH / pmRadioRecInterferencePwr
 SINR of PUCCH / PUSCH: pmSinrPucchDistr / pmSinrPuschDistr
 PRB Utilization in DL / UL : pmPrbUtilDl / pmPrbUtilUl
 RLC ACK/NACK: pmRlcArqUlack / pmRlcArqUlNack
 Transport block PWR restricted: pmRadioTbsPwrRestricted / pmRadioTbsPwrUNRestricted
 Scheduling activity per cell in UL and DL : pmSchedActivityCellDl /pmSchedActivityUeDl
 Rank distribution MIMO/ SIMO : pmRadioTxRankDistr
 Number of A2 events(UE in poor coverage) : pmBadCovEvalReport
COUNTERS FOR THROUGHPUT ANALYSIS

1. RSSI
UL Interference on PUCCH :
pmRadioRecInterferencePwrPUCCH
The measured Noise and Interference Power on PUCCH
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Unit: dBm/PRB
UL interference on PUSCH :
pmRadioRecInterferencePwr
The measured Noise and Interference Power on PUSCH
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Unit: dBm/PRB
FOR GOOD THROUGHPUT IN UL- RSSI VALUE SHOULD BE LOW (< -105 DBM)
RF INDICATORS FOR THROUGHPUT CHECK

2. UL SINR
SINR of PUCCH:
pmSinrPucchDistr
Distribution of the SINR values calculated for PUCCH .
› PDF ranges:
› [0]: SINR <= -15
› [1]: -15 < SINR <= -12
› [2]: -12 < SINR <= -9
› [3]: -9 < SINR <= -6
› [4]: -6 < SINR <= -3
› [5]: -3 < SINR <= 0
› [6]: 0 < SINR <= 3
› [7]: 3 < SINR
› Unit: dB
Condition: Each SINR value for PUCCH per UE calculated on a
TTI basis yields one sample in the distribution.
SINR for PUSCH:
pmSinrPuschDistr
Distribution of the SINR values calculated for PUSCH .
› PDF ranges:
› [0]: SINR <= -5
› [1]: -5 < SINR <= -2
› [2]: -2 < SINR <= 2
› [3]: 2 < SINR <= 6
› [4]: 6 < SINR <= 10
› [5]: 10 < SINR <= 14
› [6]: 14 < SINR <= 17
› [7]: 17 < SINR
› Unit: dB
Condition: Each SINR value for PUSCH per UE calculated on a
TTI basis yields one sample in the distribution.
FOR GOOD THROUGHPUT IN UL - FEW SAMPLES IN POOR SINR RANGES

3. PRB UTILIZATION
PRB Utilization in DL :
pmPrbUtilDl
A distribution that shows the downlink Physical Resource
Blocks (PRB) utilization (total number of used PRB by
available PRB) on the Physical Downlink Shared Channel
(PDSCH).
PDF ranges:
[0]: 0 % <= Utilization < 10 %
[1]: 10 % <= Utilization < 20 %
[2]: 20 % <= Utilization < 30 %
[3]: 30 % <= Utilization < 40 %
[4]: 40 % <= Utilization < 50 %
[5]: 50 % <= Utilization < 60 %
[6]: 60 % <= Utilization < 70 %
[7]: 70 % <= Utilization < 80 %
[8]: 80 % <= Utilization < 90 %
[9]: 90 % <= Utilization
Unit: -
Condition: One sample should be the utilization during
the sample gathering period.
PRB Utilization in UL:
pmPrbUtilUl
A distribution that shows the Physical Resource Blocks (PRB)
utilization (total number of used PRB by available PRB) on the
Physical Uplink Shared Channel (PUSCH).
PDF ranges:
[0]: 0 % <= Utilization < 10 %
[1]: 10 % <= Utilization < 20 %
[2]: 20 % <= Utilization < 30 %
[3]: 30 % <= Utilization < 40 %
[4]: 40 % <= Utilization < 50 %
[5]: 50 % <= Utilization < 60 %
[6]: 60 % <= Utilization < 70 %
[7]: 70 % <= Utilization < 80 %
[8]: 80 % <= Utilization < 90 %
[9]: 90 % <= Utilization
Unit: -
Condition: One sample should be the utilization during the
sample gathering period.
FOR GOOD UL AND DL THROUGHPUT- UL AND DL PRB UTILIZATION SHOULD BE LOW RESPECTIVELY ( <80%)

4. UL RLC NACK
RLC ACK:
pmRlcArqUlack
 The total number of successful RLC PDU transmissions
(ACKs) in the uplink direction.
 Unit: -
 Condition: Continuous measurement for Radio Bearers
aggregated to cell level..
RLC NACK:
pmRlcArqUlNack
 The total number of unsuccessful RLC PDU and RLC PDU
segment transmissions (NACKs) in the uplink direction.
 Unit: -
 Condition: Continuous measurement for Radio Bearers
aggregated to cell level.
FOR GOOD THROUGHPUT IN UL –UL RLC NACK RATIO SHOULD BE LOW
5. POWER RESTRICTED TRANSPORT BLOCK-UL
Transport block PWR restricted:
pmRadioTbsPwrRestricted
 The number of Transport Blocks on MAC level scheduled in
uplink where the UE was considered to be power limited.
 Unit: -
 Condition: A Transport Block is considered to be power
limited when the estimated required transmit power is
higher than the UE maximum transmit power.
 Counter type: PEG
 Scanner: Not included in any predefined scanner
Transport block PWR restricted:
pmRadioTbsPwrUNRestricted
 The number of Transport Blocks on MAC level scheduled in
uplink where the UE was NOT considered to be power limited.
 Unit: -
 Condition: A Transport Block is considered to be power limited
when the estimated required transmit power is higher than the
UE maximum transmit power.
 Counter type: PEG
 Scanner: Not included in any predefined scanner
RATIO OF POWER LIMITED TO NON POWER LIMITED BLOCKS SHOULD BE LOW FOR GOOD THROUGHPUT IN UL-
RATIO SHOULD BE LOW(< 50%)

6. CQI
FOR GOOD THROUGHPUT IN DL- AVERAGE CQI SHOULD BE HIGH (>10)
CQI is a feedback mechanism from UE to eNB in downlink.
 pmRadioUeRepCqiDistr gives CQI distribution in DL
 pmRadioUeRepCqiDistr is a PDF counter and it gives value in range from 0 to 15
 CQI 1-6 map to QPSK
 CQI 7-9 map to 16QAM
 CQI 10-15 map to 64QAM
7. MIMO RANK DISTRIBUTION USAGE
Rank distribution : MIMO/ SIMO : pmRadioTxRankDistr
The transmission mode / rank distributions gives more detailed information on which transmission mode
and rank is used in each UE.
PDF ranges:
[0]: Transmit diversity  same information both branches
[1]: Open Loop SM Rank 1 SIMO
[2]: Open Loop SM Rank 2  MIMO
[3]: Closed Loop SM rank 1
[4]: Closed Loop SM rank 2
Unit: - Counter type: PDF
Scanner: Not included in any predefined scanner
SM stands for Spatial Multiplexing
FOR GOOD THROUGHPUT IN DL- HIGH SAMPLES OF MIMO RANK 2 MIMO IS CURRENTLY USED IN DL ERICSSON
SUPPORTS TM2(PDF RANGE 1) & TM3(PDF RANGE 2) CURRENTLY

8. MODULATION SCHEME USAGE DL
 QPSK Samples (%) = 100 * (pmMacHarqDlAckQpsk/ (pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
pmMacHarqDlAck64qam))
 16 QAM Samples (%) = 100 * (pmMacHarqDlAck16qam / (pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
 64QAM Samples(%) = 100 * (pmMacHarqDlAck64qam/ (pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
FOR GOOD DL THROUGHPUT- HIGH USAGE OF 64 QAM AND 16 QAM SCHEME IN DL
9. MODULATION SCHEME USAGE UL
 QPSK Samples (%) = 100 * ((pmMacHarqUlSuccQpsk/ (pmMacHarqUlSuccQpsk+ PmMacHarqUlSucc16qam ))
 16 QAM Samples (%) =100 * ((pmMacHarqUlSucc16qam/ (pmMacHarqUlSuccQpsk+ PmMacHarqUlSucc16qam
))
FOR GOOD UL THROUGHPUT - HIGH USAGE OF 16 QAM SCHEME IN UL

MAJOR PARAMETERS

THROUGHPUT TROUBLESHOOTING – ESSENTIAL CHECKS
The following items should be considered when studying throughput:
 RBS Parameter Settings
EUtranCellFDD
dlChannelBandwidth / dlChannelBandwidth
(nrOfSymbolsPdcch) (Control Region Size)
noOfUsedTxAntennas  controls whether OLSM MIMO is used (2) or not.
partOfRadioPower  NOTE: this is the % part of RU capability independent of SectorEquipmentFunction::confOutputPower
settings
pZeroNominalPusch  some UEs need this to be increased or ACK/NACKs are not received successfully on PUCCH.
pZeroNominalPusch  some UEs need this to be increased from default or lots of errors seen on PUSCH
 UE Subscriber profile (End User (EPS User) subscription data is stored in the HSS)
MSISDN number
APN Operator Identifier Replacement
Subscribed Charging Characteristics
Aggregate Maximum Bit Rate (AMBR)
Max requested bandwidth in Downlink
Max requested bandwidth in Uplink
RAT frequency selection priority
APN configuration profile:
Default Context Identifier (default APN for the EPS User)
APN Configuration (every APN associated to the EPS User)

THROUGHPUT TROUBLESHOOTING – ESSENTIAL CHECKS
The following items should be considered when analyzing throughput:
 RBS TN Parameter Settings
 Enabled Features – The following features directly impact end user throughput
 Downlink/Uplink Baseband Capacity
 Channel Bandwidth (5, 10, 15 and 20) MHz
 64-QAM DL / 16-QAM UL
 Dual Antenna DL Performance Package
 Total traffic
 Relative Load of RAN system elements
 UE categories
 MIMO
 MCS
 Control Channel Configuration
 Software loads of the network elements and mobile devices

THROUGHPUT TROUBLESHOOTING
 Check whether the block error rate (BLER) is excessively high on the radio interface. If the BLER is higher than 10%,
the channel condition is poor and will result in low throughput.
 Check whether uplink interference exists, in a normal case, the UL RSSI on each resource block (RB) is about ( – {119
to 120} ) dBm when the cell is unloaded. If the RSSI is 3 dBm to 5 dBm higher than the normal value (when un-
loaded), uplink interference exists. Locate the interference source, and mitigate the interference (Could be some
external interferer or values of pZeroNominalPusch in neighbour cells are too high)
 Check whether the eNodeB’s parameter settings are correct. If the values are inconsistent, confirm whether the
settings are customized for the operator or have been changed to incorrect values
 Check whether the number of users in the cell is excessively large. If an excessively large number of users have
accessed the cell and ENodeB are exhausted when a UE accesses the cell, the user throughput will be low.
 Check whether relative license information is incorrect and if the license has not expired
 Check whether the traffic volume to the eNodeB is insufficient. A common reason for the insufficient input traffic
volume is a bottleneck transmission bandwidth at an intermediate node.

REASONS FOR LOW THROUGHPUT :
1. Cell having high traffic ( pdcch util is greater than 70%)
2. UEs are not in good RF conditions (due to that RI might be one)
3. High UL RSSI and alarms
FOR GOOD DL/UL THROUGHPUT, THE FOLLOWING THINGS NEED TO CHECKED : -
DL/UL THROUGHPUT
1. CQI (<10)
2. Rank indicator (should be 2)
3. MIMO% contribution ( Must be enabled and % should be more)
4. Modulation ( For DL 64-QAM and for UL 16-QAM should be working)
5. RRC active users should be less and UEs should be in good RF conditions.
6. Scheduling algorithm ( Proportional Fair High/ Medium/ Low and Resource Fair). Should be set as per operator specifications.
7. Check RSSI (UL N+I should b/w -110dBm >UL N+I >-119dBm).
8. Part of sector power (should be as per network design)
9. For particular UE (cell edge), we can also implement beam forming and ICIC for improving cell edge THP.
10. For UE is bad coverage need to check( Uepowerlimitedratio<70%, uebadcovelalution and CQI report)
11. We can check Other parameters performance ( Acc, Ret and HO)
12. Reduce tInactivityTimer ( Min value 10sec) value so that inactive user can be released early.
UL THROUGHPUT
1. pzeronominalpucch (-120dBm to -117dBm)
2. pzeronominalpusch (-102dBm to -98dBm)
COUNTERS FOR THROUGHPUT ANALYSIS : -
1. UL Interference on PUCCH / PUSCH : pmRadioRecInterferencePwrPUCCH / pmRadioRecInterferencePwr
2. SINR of PUCCH / PUSCH: pmSinrPucchDistr / pmSinrPuschDistr
3. PRB Utilization in DL / UL : pmPrbUtilDl / pmPrbUtilUl
4. RLC ACK/NACK: pmRlcArqUlack|pmRlcArqUlNack
5. Transport block PWR restricted: pmRadioTbsPwrRestricted / pmRadioTbsPwrUNRestricted
6. Scheduling activity per cell in UL and DL : pmSchedActivityCellDl /pmSchedActivityUeDl
7. Rank distribution MIMO/ SIMO : pmRadioTxRankDistr
8. Number of A2 events(UE in poor coverage) :pmBadCovEvalReport

LTE KPI Optimization - A to Z Abiola.pptx

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to LTE KPI Optimization - A to Z Abiola.pptx

Similar to LTE KPI Optimization - A to Z Abiola.pptx (20)

Recently uploaded

Recently uploaded (20)

LTE KPI Optimization - A to Z Abiola.pptx

Editor's Notes